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¥ THE
A \\

QUARTERLY JOURNAL

OF THE

GEOLOGICAL SOCIETY OF LONDON.

EDITED BY

| THE ASSISTANT-SECRETARY OF THE GEOLOGICAL SOCIETY.

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

VOLUME THE SIXTIETH.

1904.
LONDON:
: LONGMANS, GREEN, AND CO.
: PARIS: CHARLES KLINCKSIECK, 11 RUE DE LILLE.
SOLD ALSO AT THE APARTMENTS OF THE SOCIETY,
MDCCCCIY,

Webb

List

OF THE

OFFICERS

OF THE

GEOLOGICAL SOCIETY OF LONDON.

MAR RAAAKRRARARRALIISN

Elected February 19th, 1904.

PILLS LIS

w™

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

Vice-Prestvents,
Prof. Thomas George Bonney, Se.D.,LL.D., | Edwin Tulley Newton, Esq., F.R.S.

HRS ESA. Horace Bolingbroke Woodward, Esq.,
Sir Archibald Geikie, Sce.D., D.C.L., LL.D., E.R.S.
Sec. B.S.
Decretaries.

Robert Stansfield Herries, Esq., M.A.

Prof. William Whitehead Watts, M.A.,

M.8c., F.R.S.

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

Creasurer.
William Thomas Blanford, C.I.E., LL.D., F.R.S.

COUNCIL,

The Rt. Hon. the Lord Avebury, P.C.,
D.C.L., LL.D., F.R.S., F.L.S.

Francis Arthur Bather, M.A., D.Sc.

William Thomas Blanford, C.I.E., LL.D.,
E.R.S.

Prof.Thomas George Bonney,Se.D.,LL.D., |
E.R:S., F:S8.A,

Sir John Evans, K.C.B., D.C.L., LL.D., |
E.R.S.

Prof. Edmund Johnstone Garwood, M.A. |

Sir Archibald Geikie, Sc.D., D.C.L., LL.D.,
Sec.R.S8.

Prof. Theodore Groom, M.A., D.Sc.

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

Robert Stansfield Herries, Hsq., M.A.

Prof. John W. Judd, C.B., LL.D., F.R.S.

Prof. Percy Fry Kendall.

Philip Lake, Hsq., M.A.

Prof. Charles Lapworth, LL.D., F.R.S.

Bedford McNeill, Esq., Assoc.R.S.M.

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

Prof. Henry Alexander Miers, M.A., F.R.S.

Horace Woollaston Monckton, Esgq., F.L.S.

Edward Tulley Newton, Esq., F.R.S8.

George Thurland Prior, Esq., M.A.

Prof. William Whitehead Watts, M.A.,
M.S8c., F.R.S.

The Rey. Henry Hoyte Winwood, M.A.

Horace Bolingbroke Woodward, Esy.,
F.RS.

Assistant-Secretary, Clerk, Librarian, anv Curator.
L. L. Belinfante, M.Se.

Assistants in Office, Library, anv fHuseum.

W. Ruperi Jones.

Clyde H. Black.

Alec Field.

TABLE OF CONTENTS.

Actanp, Henry Dyke, Esq. Ona New Cave on the Eastern Side
NE aU LY ie vipat odo oe ene te ows Se OAR Adee

ARNOLD-Bemrosk£, HENry Howe, Esq. On some Quartzite-Dykes
in Mountain-Limestone near Snelston, Derbyshire (Plates

MRE MORN oe hechod aia 8 58, Sa storp/e oi Ciara eS tywan Baw mw laces s+ :

Atkin, Austin J. R., Esq. The Genesis of the Gold-Deposits of

Barkerville (British Columbia) and the Vicinity ............ :

Batpwin, WALTER, Esq.,. & Wit~ttam Henry Sorcuirre, Esq.
Eoscorpius sparthensis, sp. nov., trom the Middle Coal-Measures
Ek DERE a 2 OS MISE ale ieee nr smn aeuee ke elites oh ange

Barrow, GEorGE, Esq. On the Moine Gneisses of the East-
Central Highlands and their Position in the Highland Sequence
ener a VED ole Oc a a wleik dle nme ee ok sles

BELL, ALEXANDER MONTGOMERIE, Esq. Implementiferous Sections
miineremse (OXTOPOSHITC) 2.5. fo lel edness wee cee

Bouton, Prof. Witu1amM 8S. On the Igneous Rocks at Spring

Cove, near W2ston-super-Mare......... 0.2.02. c cece eeneece oe

. The Igneous Rocks of Pontesford Hill, Shropshire (Plates
a UE OEE E 2 Ta Set RIS BOS Dole eee oe

CunnincHaM-Craic, E. Huserr, Esq. Metamorphism in the
Loch-Lomond District (Plates II-V) ..... ccc ee eee eee

Davies, Henry Natwanient, Esq. The Discovery of Human
Remains under the Stalagmite-Floor of Gough’s Cavern,

nnENS rt OE es te A aly ae cee aye Lo ASUS abe os eo 3:

Davison, Dr. CoarieEs. The Derby Earthquakes of March 24th

Page

594

SE Ea Cais Ve Si ad fcr: 2. @ ©. nae ee 21:

. The Caernarvon Earthquake of June 19th, 1903, and its
Pero wermimnoews, (Piste) fo. gel ew ew ee ac sees stae

ELspEN, JAMES VINCENT, Esq. On the Age of the Llyn-Padarn
ere et ENON Fy oi se sca d's de cate oes on es

EneuisH, Lieut.-Col. THomas. Eocene and Later Formations
surrounding the Dardanelles (Plates XXI-XXII) ..........

we

233

372

245

1V TABLE OF CONTENTS.

Page
FEARNSIDES, WILLIAM GrorGE, Esq. On the Occurrence of a
Limestone with Upper Gault Fossils at Barnwell, uear
Cambridge: £2). cckie seis hieatie 9s ne wesw aus, Seite ee 360

FLeTT, Dr. JoHN SmitH. Notes on the Collection of Rock-
Specimens made by Col. English in European Turkey and
SIS MMOR 6 5h 6 diet, cain wa els | ee a 276

GreEGorY, Prof. J. Watter. <A Contribution to the Glacial
Geology of Tasmania (Plates VIL & VUE)... 30s eee 37

GwWINNELL, WINTOUR FREDERICK, Esq. Ona small Plesiosaurus-
Skeleton from the White Lias of Westbury - on- Severn
(AOSEP GCE) 4, 5; arcane Seger tials EAL ae eae es eee el 309

Hearey, Miss Maup. Notes on Upper Jurassic Ammonites, with
special reference to Specimens in the University Museum,

Oxford.: Now D(Plates si Xe NIM ee oy acta ee eee 54
Ho.uanp, RicHarp, Esq. Notes on Nummulites in the Turkish
Rocks described by Col. English (Plate XXV) .............. 292

JUKES-BROWNE, ALFRED JOHN, Esq. The Valley of the Teign -. 319

LorENzO, Prof. GIUSEPPE DE. The History of Volcanic Action in
the Phlegrean Fields (Plates XXVI-XXVIII) ......... .. 296

Morean, Prof. Conwy Luoyp, & Prof. Sipney HugH ReryNoLDs.
The Igneous Rocks associated with the Carboniferous Limestone
of the’ Bristol District (Plates XVI & XV). 33 20 ee eee 137

NewrTon, Epwin TuLuey, Esq. On the Occurrence of Ldestus in
the Coal-Measures of Britain(Plate 1) «2. a2¢ se eee 1

Newton, RicHarD BULLEN, Esq. Notes on the post-Tertiary and
Tertiary Fossils obtained by Col. English from the District

surrounding the Dardanelles (Plate XXIV) ................ 277
PRELLER, Dr. C.S. Du Ricue. The Age of the Principal Lake-
Basins between the Jura and the Alps (Abstract) ............ 65
. Phenomena bearing upon the Age of the Lake of Geneva
CAOSENG CE) cca leleje inva + o50.0'o » 93 vy Geta afeer ane ey eee be 316
Reip, CLEMENT, Esq. On the Probable Occurrence of an Eocene
Qutlier off the Cornish Coast... 50.2 2. soe «2s woe ee eee 118

, & Mrs. ExeEanorn M. Reto. On a Probable Paleolithic
Pioor.at Proh Sands (Cornwall) 32. ..c ho. es ee ey Tee 106

Reyno.ps, Prof. Sipney Hueu, & Prof. Conwy Luoyp Mora@an.
The Igneous Rocks associated with the Carboniferous Limestone
of the Bristol District (Plates XVI & XVI) .........:., an hake

.& Dr. AntHuR VauGHAN. The Rhetic Beds of the South-
Wales Direct. Line (Plate XVIII). .... 2.5... 25 oo eee 194

RicuHarpson, Linspaut, Hsq. The Evidence for a Non-Sequence
between the Keuper and Rheetic Series in North-West Glou-
eestershire and Worcestershire ..,... ., ...)20. eee 349

—— ———

wer” Ee ——. = SS

: TABLE OF CONTENTS. Vv

Page
Suort, A. RenDi#, Esq. A Description of some Rhetic Sections
in the Bristol District, with Considerations on the Mode of
Deposition of the Rhetic Series .......i... cece ence eeeees 170

SurcuirFE, WitiiaM Henry, Esq., & Watter Barpwin, Esq.
Eoscorpius sparthensis, sp. nov., from the Middle Coal-Measures
oo SS Se oa ee ee ee ee 594

Vaucuan, Dr. ArtHuR, & Prof. SwNey HuGH Reynoxps. The
Rheetic Beds of the South-Wales Direct Line (Plate XVIII).. 194

WALKER, [the late) Epwarp Eaton. Notes on the Garnet-bearing
and Associated Rocks of the Borrowdale Volcanic Series

PENNE OPV Oo ake. Sioa is ae nas Paha Sle Mireid te sa wks 70
Woopwarp, Dr. ARTHUR SmMitH. On the Jaws of Ptychodus from

RRR IE Fe, nian ssp o niaoeee oa de bP deme we bet 133
———. [Diplomystus marmorensis, sp. NOV.) 2.6.6. e ee eee ee eee 284

PROCEEDINGS.

Proceedings of the Meetings ................. Ste orem i, CV
SIMMER Oe CNG ony cd oy of veiw v WMS ede sak» > ix
List of Donors to the Bapraryy: 3) Sos. 25: ¢: pe tat ap ates: <> ins XIV
2 ee ee XXV
fast at Woreien Correspondents... 2.12.20 2. cece eee eee XXV1
Seer Ww ollaston Merdallisis: .. 2... ck cence cece sees Xxvli
EO XXIX
Awards of the Daniel-Pidgeon Fund ..................-005 XXX, CIX
8 SE Te nee Xxxi
I IISRECSE boon rl eate Pati edd sind @ Gs a win ws ws XXxil
LS 2 SU Xxxili
Applications of the Barlow-Jameson Fund ...............-.. Xxxill
NN I aie. ie oc Lele ds. ule-s vetoes ed ws oe wes XXXIV
Award of the Medals and Proceeds of Funds................ xi
Anniversary Address delivered by Sir Archibald Geikie ..,... xlix
tC E MINT fol an oisis ce bow d's oo ane ew o> * -s cv
Regulations as to the Admission of Visitors ............005- evi
Regulations as to Exhibits at Meetings ................4-.. exl

al TABLE OF CONTENTS.

Barrow, G., Esq. On a Striated Boulder from the Scilly Isles.

Lomas, J., Esq. Ona Piece of Faulted Slate from the Volcanic
plates of Ulpha (Cumberland) \.. 5... ©. :c0-- se se eee

Roxsarts, N. F., Esq. On Flint-Implements from Surrey ....

Warts, Prof.W.W. On British Association Geological Photo-
SMAPS! is ois Fig bases ahacd » oo os< WR tees eke

LIST OF THE FOSSILS DESCRIBED AND FIGURED
IN THIS VOLUME.

Name of Species. Formation. Locality. Page
ForAMINIFERA.
Nummulites distans, var. pl.) \ ( (
eB i | | : | 293-94.
cage at
ae aa figs.’ + Hocene '*.<....0< 4+ VeEnitee 52, <5005- 4 999-93
eee eee eee eee eee eee TEE ee eee Soe / 1 ’ , | =
a | j | | 294
—— variolaria (2?) .....c60ee J ik | 294

MADREPORARTA APOROSA.

Cladocora cf. articulata ...... . Gorgona Deré... 290

Trochocyathus, sp. .......4.40. } hee | { Vernitza ......... 290
Mapreporaria Funeipa.

sot ae ae re | Middle Eocene | Vernitza ......... 290

ARACHNIDA.

Eoscorpius sparthensis, sp.! {Middle Qoal- |}, | ey
VAG i ie | | Measures sit f ee Sees a2

LAMELLIBRANCHIATA.

Anomia sp., pl. xviii, fig. 1 ... ) if {201
Avicula contorta .....00.cs0-00 | | | | 202-203
Cardinia concinna aff. regu-, | 1 ; |
laris, text-fig. 4 & pl. xviii, ¢ Rhectic = So re 4 Sodibary. ..-<..::. 4
oa eecainera es | | | | 204-205
Cardium cloacinum, fig. 6...... |) ki | | 207-208
: ! '
es a Be Miocene ......... | Gherme Tepé...| 282-83
TRMOUNE Sagan vanes dnlonn ee (ica aC areas 3 | Sodbury 5... ::..: 208
Corbicula semistriata, pl. xxiv, |
fea) BIA 2S. ow BOUT ie snes |‘ Oligocene ...... Masatly ......... | 287
COREE Sire acc thagee -odaebir ss J | Keshan: .....::.: | 287-88

Vill FOSSILS DESCRIBED AND FIGURED.

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

LAMELLIBRANCHIATA (continued).

Didacna crassa, pl. xxiv, figs. { | |

, & 2 Sh Daan cacy ag sa PHOGENE: s.u5- <0 Gallipoli ......... Uleal
Dreissensia polymorpha, pl. | |

XXIV, fig. 3 ........eeeeeeee te ee
Bes. TER en] | Mioeeme oan Teke-keni ..... 281
Ree Pr Se) ehooetic mies Callepdli hes 280
Fimbria subpectunculus ...... Middle Eocene .| Tzenguerli Deré.| 289-90
eee ee et Minoan eae oe Heraklitza, &e. .| 282
Modiola sodburiensis, Sp. nov., \ ( f

pl. xvii, figs. 3&3a ...... | | 203
Ss UINUING os.5c2sekotseceeuat nes | 204
Pect loniensis, pl. xviil,} | : | |

ie ae Ai pe be _ ee t Rheetic Seance eee 4 Sodbury... 4 209
Pleurophorus elongatus, fig. 5 . | | 205-207
Plicatula cloacina, sp. nov., |

text-fig. 3 & pl. xviii, fig. 5 .| ) \ \ 202
Prosodacna cf. stenopleura, : Seas =

pcecay ifipe: One a | Miocene alachads < Meke-kewh’ eves 281
Spondyl ubspi lela eat p ;
—e = of ee pie } Middle Eocene .| Tzenguerli Deré.| 289
ae Delesserts, (pl. xxiv, “He. | Miocene eee Potamina Deré .| 283

GASTEROPODA.

Lyrcea Bonelli, pl. xxiv, figs. | |

Sc Gi Cpe a es Eee ess ate ae De Rscene | Teke-keui ....... 281
Melania cf. Escheri, pl. xxiv,| (7 |

Care bee eee emmy cet aN | | Potamina Deré. 283
ae costata, pl. XXIV i oeene ds. ee. va: | San Stefano ..., 283

= of. fusiformis Le one Oligocene al Kesham. <2232..0: | 286-87
& oe Bia ee. = Miocene ......... | Potamina Deré .| 284

j | }

AMMONOIDEA.

Olcostephanus Pallasianus, |

var. nov., fig. 3 & pl. xii .... $ Kimeridge Clay. Chippinghurst . 60-61
| ?

Perisphinctes biplex, pl.x ... 57-58
plicatilis, fig. 1 & pl.ix. Upper Corallian| ? 50-57
y , ° ‘A
Re SRIEGUE IEE j Ampthill Clay...| Hawnes ......... 58-60
10) [eye cia Meee Serle ee |
ELASMOBRANCHEI.
Edestus minor, fig. 1 ............ |} | ( Wntdidna: 27.222. [3
triserratus, sp. nov.,) + Coal-Measures . Nettlebank ee
11 Fue 0) Be re PREC rey em | (Staffs.) ...... | segg.

Ptychodus decurrens, pl. xv &
ee Sree | Lower Chalk ...! pias ibe ee | 1383-35

5 aie ere aes

ite ny im ss
" " wins 3 ;
| ‘ th FOSSILS DESCRIBED AND FIGURED. 1x
_-‘Name of Species. | | Formation. | Locality. | Page
TELEOSTEI.
Rreeonystes marmorensis, Sp. | | a
“20%, pl. xxiv, fe. 98. ..... Miocene ........ Sarkeui ..... w..| 284-85
SAUROPTERYGIA,
Plesiosaurus cf. bibractensis a White Lias .. | * heel a | 359
UNGULATA.
eee cl. inns, pl. | \ Oligocene en Masatly ......... | ~286

Ee ee

EXPLANATION OF THE PLATES.

PuatTE PAGE

I seen TRISERRATUS, SP. Nov., to illustrate Mr. E. \ 1
T. Newton’s paper on that forse Ree,
Microscore-Sections oF Rocks FROM THE LocuH-

Lomonp Drstrict, to illustrate Mr. EK. H. Cun- 10
ningham-Craig’s paper on pu ea ee in
GALE CRN chon en tea ta dost th as eaaceccteexe aides
LONGITUDINAL AND TRANSVERSE SECTIONS AND PLAN

VI or Cave at Monkey's Quarry, GIBRALTAR, to 30
| illustrate Mr. H. D. Acland’s paper on that cave
Sxetcu-Map or THE GuwLACIATED AREA AROUND }

VII & VIII Mount Lyett; anp Views oF Mount Owen, =
etc., to illustrate Prof. J. W. Gregory’s paper on
the Glacial Geology of Tasmania ..............-.4.
PERISPHINCTES PLICATILIS ; PERISPHINCTES BIPLEX ;

IX-XII PERISPHINCTES VARIOCOSTATUS ; AND OLCOSTE- 5A.
; PHANUS PALLAsrANvs, to illustrate Miss Healey’s
paper on those ammonites ..........csc--ceceeeeenees

MrcroScoPE-SECTIONS OF RocKS FROM THE Phage Pe |
-
70

XIII & XIV DALE Vo.ucanic Series, to illustrate the late
EK. E. Walker’s paper on those rocks ...............

XV { Prrcuopus prcurrens, Ag., to illustrate Dr. A. 8. 133
Woodward’s paper on that fossil -..............00+.

(Map suowrne THE DistRIBUTION OF THE CARBONT- \
| FEROUS Votcanic Rocks IN THE Brisrou Dis- |
- \ Tricr ; and Microscopn-Sections oF Basatr, or
bby hi bo Asu, etc., to illustrate Prof. C. Lloyd Morgan’s f -
; & Prof. S. H. Reynoids’s aig on the above- |
Mp BEN e eth FOCI Aoi 97 o cwatuatos badedoacs iieckedennesues J

: Ruatic Lameiirrancuiata, to illustrate Dr. A.] 5
—— { Vaughan’s notes on those a eee } ath

Mar or tHe AREA AFFECTED BY THE DerBy DartH- |

XIX QUAKE OF Marcu 241, 1903, to illustrate Dr. C. 215
| Davison’s paper on that earthquake ............... |
Map or THE AREA AFFECTED BY THE CAERNARVON |

XX Eartuq@vake or June 1Yru, 1903, to illustrate | 233

Dr. C. Davison’s paper on that earthquake ...... J

xl EXPLANATION OF THE PLATES.

PLATE PAGE

(Guotogican Sxetcn-Mar or THE CouNTRY sUR- |
| ROUNDING THE DARDANELLES ; PROBABLE FOLDINGS
oF Lower TERTIARY, AND CoAst-Lings oF UPPER |
XXI-XXTIT{ = Tertiary Formations surrounptine THE Dar-} 248
DANELLES; and Kery-Map, to illustrate Col. T.
| English’s paper on Eocene and later formations |
\

in that-varea, <.i.-2<: teen stub tre caben eee poeta acetiee )

( TERTIARY FOSSILS FROM THE COUNTRY SURROUNDING
XXIV THE DARDANELLES, to illustrate Mr. R. B. New- $ 277
| ton’s notes on those fossils ............ EY re

>

NUMMULITES FROM THE COUNTRY SURROUNDING THE
XXV DarDANELLES, to illustrate Mr. R. Holland’s
notes.on thosestossils: ges. 6..cecu-tence eee boa ae Meme

(GxotocicaL Sketcu-Map or tun Bay oF Naptes ;
Sections Across THE Bay or Napies; and Gnao- |
LOGICAL SKkETCH-Map oF THE PuLtEGR#AN FYExDs, + 296
to illustrate Prof. G. de Lorenzo’s paper on the |
history of volcanic action in that area ........ Sei)

XXVI-XXVITI

XXIX

|
t
HoumAn SKULL FOUND IN GouGu’s Cavern, CHEDDAR, |
to illustrate Mr. H. N. Davies's paper on recent

discoveries In that -Gavern.s.c.cescacssdeceee sac eeeeeee

[ QuUARTZITE-DYKES IN Movstain-LimestoNe NBAR }

é Se NELS ERBYSHIRE); al -Suc- |

XXX & XXKI Syetston (D sHIRE); and Microscorz-Suc
TIONS OF Rocks from the same, to illustrate Mr.H. {|
H. Arnold-Bemrose’s paper on those dykes ...... |

ew Liyn-Paparn Dyke-Rocks, to illustrate Mr. J. V. 9
—— { Elsden’s paper on the age of those dykes ...... hee } ai

(Guoxtocicat Map oF THE GiLBert’s-BrivGE AREA, \

Guen Titt ; and Microscope-Srcrions or Rocks |
XXXITI-XXXVII{ From rue East-Centran Hieutanps, to illus- + 400
| trate Mr. G. Barrow’s paper on the Moine |

. . |
{| Gneisses in that area.......... so tupids (ache cewtel meee ee |

(GroLocrcaL Sxetcn-Map or Ponvtesrorp Hut; )

| SECTIONS THROUGH, AND ALONG THE LowER WEsT- |
XXXVILI-XL1II 4 me AND SOUTHERN Bianks oF, POoNTESFORD { 50)

ILL; and Microscopse-Secrions oF RHYOLITEs,

| Turrs, ete., to illustrate Prof. W. 8. Boulton’s |

| paper on the igneous rocks of that hill ............ 7

ERRATUM,

Plate XXXII, for ‘Glenmhaire’ read ‘ Glen Mhaire.’

ee ee.

PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES,

a as

boo

bo

bo

BESIDES THOSE IN THE PLATES,

PAGE
See WAGE POR MRS MENOP 5525 << owen ¢ssncestes inn -vodenechenacevases 2
Segments of Edestus triserratus, sp. nov., restored ............++ 6
Section from Aberfoil to Allt a’choinn ....................600 ceeees 13
Crystalline gneiss from Inversnaid (microscope-section)......... 20
Sketch-map of the Loch-Lomond District.......................266 25
Section at Monkey’s Quarry, Gibraltar .......... Paidacapkeenk ret: 1

Section of the floor in the cave at Monkey’s Quarry, Gibraltar. 32
Glaciated boulder from the Gormanston Moraine ............... 44

Sketch-map of North-Western Tasmania, illustrating the

range of the Pleistocene glaciation .....................:esesseeeees 50
Suture-line of Perisphinctes plicatilis.............0ccccccceececenceece 55
Suture-line of Périsphinctes variacostatus, restored ............... 58
Suture-line of Olcostephanus Pallasianus, var. nov. .....:..-..- 60
Diagrammatic sketch of an exposure north-north-west of Blea

Crag, Langstrath ........... seeeetesssestaeeettaeeeeesseesacteatetecs 72
Diagrammatic section through Rosthwaite Fell .................. 89
Banded ash and garnetiferous intrusive rock at Great Crag

On NET) ASR RRS Sg I See Se ee eee 92
Section of the cliff at the western end of Prah Sands ............ 108
Rude implement (?) made of vein-quartz ..................cseeeeeee 109
Map ot South-Western Cornwall) -... 122.52. 00200 5... yet.e..e-seecee 115

Diagrammatic section across the St. Erth Valley (Cornwall)... 116

River-valley section at Wolvercote (Oxfordshire) ....,.......... 122

Xiv

PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES.

Fic. PAGE
2. Section in the Drift at Peartree Hill (Oxfordshire) ............ 128
Oral aspect of the mandible of Ptychodus decurrens, restored . 134
1. Geological map of Middle Hope or Woodspring .................. 140
2. Westernmost exposure of the volcanic series on the shore, at
Middle Hope or Woodspringy.. 2.2 -cocuscee eee eee eee 142
3. Sketch illustrating the details of the above exposure ............ 143
4. Upper ‘part of the volcanic series at Woodspring, seeond
exposures ger-ee 5: ee yee re Peace omnia: 4
1. Lenticles of lava and tuff making up the ‘main sheet of
basalt * [at SpringiCovel 2 eesends.c5<saetca esac eee 159
2. Oval, slaggy lumps of basalt-lava surrounded by fluxion-tuff . 162
3. Lump of basalt-lava, enclosing a lump of tuff and of limestone,
and itself enclosed in coarse fluxion-agglomerate ............ 162
4. Band of coarse agglomerate in basalt-lava ............ceseeeeec ees 165
5. Junction of basalt and an included mass of limestone............ 165
6, Included mass: of limestone im basalt yey..sc- rere eee eee 165
Fo Mhimesvone ineluaed an basalt... scpecsvecnecteneee ena eae eee 166
8. Portion of an included lump of limestone in basalt ............ 167
1. Black Shales of the Rhetic, resting unconformably upon Old
Red Sandstone, west of Chipping-Sodbury railway-station . 196
2. Section from Lilliput Bridge to near Chipping-Sodbury railway-
BUEALION | sca aus ctetsceslenicn tate temas een cet ee rece Ea. ae eee eee 198
3. Diagram of Plicatula cloacina, sp. NOV, s.0.....s0¢202-.--+»>+--n0= 00° 202
4, Diagram of Cardinia concinna aff. C. reqularis .........+2-0-.00- 204
5. Pleurophorus.elongatus, Moore 0: fyecessescasrause ee smeecere ces eee 205
Gs WWardium Gloacinum. Oar. Je ccsccsutentenentet mete ees ts oe eee 207
1. Record of the earthquake of March 24th, 1903, registered at
Birmingham by an Omori horizontal pendulum ............... 22
2. Map of the Derby earthquake of May 3rd, 1903.................. 230
1. Record of the earthquake of June 19th, 1903, registered at
Birmingham by an Omori horizontal pendulum ............... 236
2, Map illustrating the area affected by after-shock / of June 19th,
NGO Baigevnisides coeesase nant eeeesaeteGr a ens cuseneee aes ecnce ye ee eee 239
1. Coast-cliffs of the Tekfur Dagh, northern shore of the Sea of

TY Fc 10) ec: ene enue tS ON 2) ge ae a PR Raber 248

Fic.

bo

PROCESS-BLOCKS AND OTHER ILLUSTRATIVE FIGURES, p68

PAGE

Vertical Oligocene strata at Combos, unconformably overlain
by horizontal Miocene terraces .......,...,ccseseecrssseseseeseres 252

The andesitic hills of Imbros, with a distant view of Megalai
ce cos alps asp omnes Seem adae Vpeborsanenana de dian anee 254
Promontory of Megalai Kephalai, island of Imbros............... 260
Seemann OF tHe OSD T UA oo eee a csp pes 9tdcwsene=tns «Seemann oveceesss 262

Raised beach at Hora lighthouse, north-western coast of the
cia WN BR PPO PR coro, tA eed ies Sch neon ae alae = de petal nies <naisiwape 264
Ancient river-channel at Maitos, Dardanelles ..................... 264
Cliffs of soft Miocene deposits along the Dardanelles ............ 266

Mediterranean shell-beach at Hora, 405 feet above sea-level ... 268

Map illustrating the drainage-area of the River Teign ........, 320
Map of the neighbourhood of Dunsford ....................06. 327
Map of the neighbourhood of Ashburton ................6.....s00 529
Plan of part of Gough’s Cavern, Cheddar.....................00e00 335

Diagrammatic section through the deposits in the entrance and
MEIOONC GE CZGUEIN S CBVEPE. ©. cocce sc ccetnes peg -demcess stcvnvenese 336

Dome-like mass of granular and semi-crystalline material

Longitudinal section of the deposits in the lateral fissure g
anya EE SRR W OEE Cie cease ose asp Ca cas saasaaeetiean es panavecwaccesie « 340

Transverse section through the same fissure ..................0.0005 341

Sections of tibiz illustrating degrees of platyenemism, and
photograph of the tibia from Gough’s Cavern

Flint-blades, borers, and scrapers, found in association with
human remains in the cave-earth of Gough’s Cavern ......... 345

Map showing the relationship of anticlinal and synclinal
flexures in the Lias, etc. to those of which there is evidence
in the Inferior-Oolite Series

Section showing the relationship of the Rhetic deposits below
the Bone-Bed to the Keuper Marls ...................sceceeecees 306

Sketch-map of the Llyn-Padarn district...........0.......cccceseneee 376
Section of the Coal-Measures at Sparth Bottoms (Lancashire). 395
PGSEOTFIOES SPATERCMIES, SP. TOV. 9 agcoce se nnsdnctnsoyavssccevcacseusaves 396
Abdominal segments of the Same .4.....0..-.-....-sscecsceseeseceees 397
General map of a portion of the East-Central Highlands

Typical view of the Moine Gneisses in the bed of the Tilt,
looking up stream from Gilbert’s Bridge .....................05- 404

Xvi

i Es)

bo

Or

PROCESS--BLOCKS AND OTHER ILLUSTRATIVE FIGURES.

PaGE

Typical scar formed of Moine Gneisses, showing the resem-
blance to unaltered sandstones ............cceeeceeeeeee Rae eae 405
Geological Map) of Glen “Ohuntes.c....-221< ones eee ee eee 422

Line of erosion in fine Moine Gneisses at the base of the Main
WG IMESFONG 00. Sosiccceecl casoos scene Ques eee Mae CORRE ee eT 430

Diagram showing the Dark Schist and Parallel-Banded Rocks
apparently on opposite sides of the Limestone, while in
reality they are.on the same Side...........5.06.2...c0cceeesdseareee 431

Diagram showing the true succession of the rocks described... 438

Diagram to illustrate the mode of arrangement of the areas in
which the typical flaggy Moine Gneisses now occur, ete. ... 441

Section across Glen Tilt, passing close to Gilbert’s Bridge ...... 444
Sketch of a nodule of complex structure.......,..........sesse0sesee- 460
Complex. vesicle in-artifieialy slag, \s.scsc-< see aene se eae 461
Sketch-map showing Pontesford rocks faulted against Cambrian
shales, at the top of the road leading to Pontesbury ......... 465
Section under the fence, western flank of Pontesford Hill ...... 468

Roughly-parallel wavy ridges on a weathered surface of basalt. 479

PROCEEDINGS

OF THE

GEOLOGICAL SOCIETY OF LONDON.

SESSION 1908-1904.

November 4th, 1903.

Sir Arcarpatp Gerkie, D.C.L., D.Se., F.R.S., Vice-President,
in the Chair.

Lieut.-Col. George Lyon Tupman, F.R.A.S., Hillfoot Observatory,
Harrow; and Richard Hansford Worth, Esq., Assoc.M.Inst.C.E.,
4 Seaton Avenue, Plymouth, were elected Fellows of the Society.

The List of Donations to the Library was read.

The Secretary announced the presentation, by Sir John Evans,
K.C.B., D.C.L., F.RS., For.Sec.G.8., of a photogravure-portrait of
himself.

The following communications were read :—

1. ‘Metamorphism in the Loch-Lomond District.’ By E. Hubert
Cunningham-Craig, Esq., B.A., F.G.S."

2. ‘On a New Cave on the Eastern Side of Gibraltar.’ By
Henry Dyke Acland, Esq., F.G.8.

The following specimens, etc. were exhibited :-—

Rock-Specimens, Microscope-Sections, and Lantern-Slides, ex-
hibited by E. H. Cunningham-Craig, Esq., B.A., F.G.S., in illustra-
tion of his paper.

Specimens from the Cave at Monkey’s Quarry, Gibraltar, and
Photographs of the Cave, exhibited by H. D. Acland, Esq., F.G.S.,
in illustration of his paper.

1 Communicated by permission of the Director of H.M, Geological Survey.

VOL, LX. a

ii PROCEEDINGS OF THE GEOLOGICAL socrETY. [Feb. 1904,

Specimens of ‘ Paleofractured’ Flint from the excavations now
in progress in the Mall, S.W., exhibited by the Rev. H. H. Winwood,
MAS HGS.

A Concretion from Vancouver Island (B. C.), exhibited by T. W.
Reader, Esgq., F.G.S.

Sheet 317 (Chichester) of the Geological-Survey colour-printed
l-inch Drift-Map, peesoated by the Director of that Survey.

Three Sheets of the =7; sai , Map of the Geological Survey of Austria-
Hungary, presented by the Director of that Survey.

November 18th, 1903.

Sir ArcnizaLp Gertz, D.C.L., D.Sc., F.R.S., Vice-President,
im the Chair.

William Nobbs Harrop, Esq., Koh-i-Noor Mine, Kanowna
(Western Australia), was elected a Fellow of the Society.

The List of Donations to the Library was read.

The following communications were read :—

. ‘Notes on Upper Jurassic Ammonites, with special reference
to eee in the University Museum, Oxford: No, 12 ayy
Miss Maud Healey. (Communicated by Prof. W. J. Sollas, M.A.,
ser BLD... FURS... F:G.5.)

2. ‘On the Oceurrence of Edestus in the Coal-Measures of Britain.’
By Edwin Tulley Newton, Esq., F.R.S., V.P.G.S.’

The following specimens and photographs were exhibited :—

Specimens of Hdestus Heinrichsti, N. & W., from the Coal-Measures
of Illinois, exhibited by Dr. A. Smith Woodward, F.R.S., F.LS.,
F.G.S. ; andaspecimen of Edestus triserratus, sp. nov., from the Coal-
Measures of Smallthorne (North Staffs), exhibited by the Director
of H.M. eae. Survey, in illustration of the paper by E. T. Newton, ’
Beg alt... VebeGan.

Photographs exhibited by Prof. W. J. Sollas, D.Sc., LL.D., F.R.S.,
F.G.8., in illustration of the paper by Miss Maud Healey.

Specimen of Ammonites variocostatus from the Corallian of
Osmington, exhibited by the Rev. J. F. Blake, M.A., F.G.S.

* Communicated by permission of the Director of H.M. Geological Survey.

Vol. 60. ] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. lll

December 2nd, 1903.

Sir Arcarpatp Gerriz, D.C.L., D.Se., Sec.R.S., Vice-President,
in the Chair.

Paul Brihl, Esq., Professor of Physical Science, Civil-Engineering
College, Sibpur, near Calcutta; Donald Fraser Campbell, Esq.,
36 Oakley Crescent, Chelsea, S.W.; John Chadwick, Esq., C.E.,
Richmond House, Bletchley (Bucks); Maurice Deacon, Esq.,
Whittington House, Chesterfield; Henry Dewey, Esq., Clerk to
the Geological Survey, Bembridge, Broomhouse Road, 8.W.; J. A.
Foote, Esq., P.O. Box 3203, Troyville, Johannesburg (Transvaal) ;
Benjamin Atherton Hampson, Esg., Hampson’s Buildings, Smith
Street, Durban (Natal); William Taylor Heslop, Esq., Manager,
St. George’s Colliery, Halting Spruit (Natal); Henry Home, Esq.,
C.E., Biggleswade (Bedfordshire); Henry Kidner, Esq., 8 Derby
Road, Watford ; Hugh John Melliss, Esq., B.A., 30 Denning Road,
Hampstead, N.W.; John Pollard, Esq., M.Inst.M.E., Hall Croft,
Bradford Road, Wakefield; Robert Heron Rastall, Esq., B.A.,
Christ’s College, Cambridge ; Charles Howard Sidebotham, Esq.,
Assoc.R.S.M., 91 Manchester Road, Southport; George Howlett
Tipper, Esq., B.A., Geological Survey of India, Calcutta; Charles
Herbert Wilson, Esq., Mining Engineer, Port Darwin (Northern
Territory of South Australia); and Offen Charles Witherden, Esq.,
Port Darwin (Northern Territory of South Australia) were elected
Fellows of the Society.

The List of Donations to the Library was read.

The following communications were read :—

1. ‘Notes on the Garnet-bearing and Associated Rocks of the
Borrowdale Volcanic Series.’ By the late Edward Eaton Walker,
Esq., B.A., B.Sc. (Communicated by J. E. Marr, Esq., M.A., F.RS.,
F.G.S.)

2. ‘A Contribution to the Glacial Geology of Tasmania.’ By
Prof. J. Walter Gregory, D.Sc., F.R.S., F.G:S.

The following specimens, etc. were exhibited :—

Rock-specimens from the Borrowdale Volcanic Series, exhibited
by J. E. Marr, Esq., M.A., F.R.S., F.G.S., in illustration of the
paper by the late E. E. Walker, Esq., B.A., B.Sc.

Photographs of Northern Tasmania, exhibited by Prof. J. W.
Gregory, D.Sc., F.R.S., F.G.S., in illustration of his paper.

Geological Survey of Egypt: Maps of the Surface-Deposits of
Mersa Matru, and Ras Allen Rum, by J. Ball, on the scale of —

1903, presented by the Director of that Survey.

iv PROCEEDINGS OF THE GEOLOGICAL socirTy. [Feb. 1904,

December 16th, 1903.

Sir ARCHIBALD Getxis, D.C.L., D.Sc., Sec.R.S., Vice-President,
in the Chair.

Edward William Handcock, Esq., 32 Quarry Hill, Tonbridge ;
John Flesher Newsom, Ph.D., Associate-Professor of Geology &
Mining in the Stanford University, California (U.S.A.); and
Edward Payne, Esq., Royal Colonial Institute, Northumberland
Avenue, W.C., were elected Fellows; and Prof. Anton Koch, of
Budapest, and Prof. Albrecht Penck, cf Vienna, were elected
Foreign Members of the Society.

The List of Donations to the Library was read.

The following communications were read :—

1. ‘The Igneous Rocks associated with the Carboniferous Lime-
stone of the Bristol District... By Prof. Conwy Lloyd Morgan,
LL.D., F.R.S., F.G.8., & Prof. Sidney Hugh Reynolds, M.A., F.G.S.

2. ‘A Description of some Rheetic Sections in the Bristol District,
with Considerations on the Mode of Deposition of the Rheetic Series.’ *
By A. Rendle Short, Esq., B.Sc., M.B., B.S. (Communicated by
Prof. 8. H. Reynolds, M.A., F.G.S.)

The following specimens and maps were exhibited :—

Rock-Specimens, Microscope-Sections, Photographs and Lantern-
Slides, exhibited by Prof. C. Lloyd Morgan, LL.D., F.RS., F.G.S.,
& Prof. 8. H. Reynolds, M.A., F.G.S., in illustration of their paper.

Specimens exhibited in illustration of the paper by A. Rendle
Short, Esq., B.Sc., M.B., B.S.

Copies of three new colour-printed Geological-Survey maps :—
New Series, Sheet 248, Pontypridd (Drift) by A. Strahan, ete. ;
and Sheet 263, Cardiff (Solid & Drift) by A. Strahan, etc., presented
by the Director of that Survey.

January 6th, 1904.

Sir ArcHiBALD GetKiE, D.C.L., D.Sc., Sec.R.S., Vice-President,
in the Chair.

Reginald Francis Duke, Esq., A.M.I.M.E., ‘ Banyana,’ Little-
hampton ; William Norman-Bott, Ph.D., F.C.S., Royal Societies’
Club, St. James’s Street, S.W.; and Hugh Whittall, Esq., Mining
Engineer, Constantinople, were elected Fellows of the Society.

[* Read under the title of ‘The Rheetic Beds of England.’)]

Vol. 60.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. Vv

The following Fellows, nominated by the Council, were elected
Auditors of the Society’s Accounts for the preceding year:
G. T. Prior, Esq., M.A., and F. W. Rupzer, Esq., 1.8.0.

”-

The List of Donations to the Library was read.

Mr. J. Lomas, in exhibiting a piece of faulted slate from the
volcanic slates of Ulpha in Cumberland, said that the thin
band showing faults was very limited. The movements being con-
fined to this one strip, must be due to changes in the bed itself and
have no relation to larger movements. On tracing the faults on
one slab, cutting along the fractures, and reconstructing so that a
well-defined band was continucus, it was found that a horizontal
shrinkage of 1 in 6 had taken place. The faulting may be
due to the cooling and shrinking of an ash deposited at a high
temperature, or the closer packing of the particles as the mass
settled down. Similar small faults may often be observed in
Glacial sands ; and in this case they are obviously due to movements
consequent on a closer packing of grains.

Mr. N. F. Rozarts referred to the flint-implements which
he exhibited, on. which he invited criticism, as Plateau or Eolithic
implements from the valley of the Wandle, some of which were
obtained from the highest parts of the North Downs, in Surrey, at
an altitude of 800 feet. The implement exhibited, which was of
distinct Paleolithic type, was from Croydon. He also exhibited
implements from the gravel at Mitcham, on behalf of Mr. A.
J. Hogg.

Mr. Crincu remarked that, after a careful examination of the
so-called ‘implements’ found in the gravel at Mitcham, he was
unable to see upon them any traces of human handiwork or of wear
arising from use by man. In his opinion they had been shaped
entirely by natural forces. He was glad, however, to see on
the table a typical Palzolithic implement, much rolled and drift-
worn, which had been found at Thornton Heath.

Mr. A. M. Bett acknowledged the working on some eoliths
exhibited, especially on one of the hollow scraper-forms, but saw
no reason to think them of earlier age than the ochreous and worn
Paleolithic implement which was also shown. Probably, in fact,
that implement was older than any eolith exhibited—certainly it
was much more rolled and altered than the majority of them.

The following communications were read :—

1. ‘On a probable Paleolithic Floor at Prah Sands (Cornwall).’
By Clement Reid, Esq., F.R.S., F.L.S., F.G.S. and Eleanor M. Reid,
B.Sc.

2. ‘ Implementiferous Sections at Wolvercote (Oxfordshire).’ By
Alexander Montgomerie Bell, Esq., M.A., F.G.S.

vl PROCEEDINGS OF THE GEOLOGICAL SOCIBTY. [Feb. 1904,

In addition to the exhibits mentioned on p. v, the following
specimens, etc. were exhibited :—

Implements made of Vein-Quartz, from the Ancient Floor at

Prah Sands (Cornwall), exhibited by Clement Reid, Esq., HES.,
F.L.S., F.G.S., and Eleanor M. Reid, B.Sc., in illustration of their
paper.
i series of Flint and Quartzite-Implements from Wolvercote
(Oxfordshire), Limpsfield (Surrey), and other localities; Lantern-
Slides of two sections at Wolvercote; and Microscopic Preparations
of Plant-Remains from the River-Gravel, exhibited by A. M. Bell,
Esq., M.A., F.G.S., in illustration of his paper.

Implements from the Narrows, Yadkin River, Montgomery Co.,
North Carolina (U.S.A.), exhibited by E. T. Newton, Esq., F.R.5.,
WeP-G.S.

Vegetable Remains in Flint from Sunningdale (Berkshire),
exhibited by E. A. Martin, Esq., F.G.S.

January 20th, 1904.

Sir Arcurpatp Gerxin, D.C.L., D.Sc., Sec.R.S., Vice-President,
in the Chair.

The List of Donations to the Library was read.

The Srcrerary announced that the Council had communicated the
following resolution of sympathy to Mrs. Etheridge :—

‘That the Council desire to place on record their great regret at the death of
Mr. Rozsert Erueripax, F.R.S., formerly President of this Society, who did so
much during his long life to advance Geological Science and to promote the
interests of the Society.’

The Cuairman read the following letters for the first time, in
accordance with Sect. XI, Art. 8 of the Bye-Laws :-—

‘January 20th, 1904.

‘To the Secretary, Geological Suciety, Burlington House, W.

‘Sir,
It is intended on the part of the Council to move :—

(1) That Bye-Laws, Sect. XII, Art. 38, and Sect. XII, Art. 4, 1° be repealed.

(2) That the following new Bye-Law be enacted, to be called Sect. IX,
Art. 12a, to come between Arts. 12 & 13 of Sect. 1X: Persons not
belonging to the Society, if introduced by Fellows or Foreign Members,
may be present at General Meetings, subject to such regulations as the
Council may make from time to time.

(3) That the following alteration be made in Bye-Laws, Sect. XIX, Art. 1:
That the words ‘‘ subject to such regulations as the Council may make
from time to time” be added after the words “ General Meetings of
the Society” at the end of line 4.

Signed on the part of the Council,
ARCH, GHIKLE,’

Vol. 60. ] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. vii

‘January 20th, 1904.
_ ‘To the Secretary, Geological Society, Burlington House, W.
a is intended on the part of the Council to move: —That Bye-Laws
Sect. XIV, Art. 4, and Sect. XXI, Art. 6 be repealed.
Signed on the part of the Council,
Arcu. GEIKIE,’

The following communications were read :—

1. ‘On the Jaws of Ptychodus from the Chalk. By Arthur
Smith Woodward, LL.D., F.R.S., F.L.S., F.G.S.

2. *On the Igneous Rocks at Spring Cove, near Weston-super-
Mare.’ By William 8. Boulton, Esq., B.Sc., A.R.C.S., F.G.S.

The following specimens were exhibited :—

Jaws of Ptychodus decurrens, Ag., from the Lower Chalk of
Glynde (Coll. Henry Willett); a Photograph of the Dentition
of Ptychodus Mortoni, Mantell, from the Upper Cretaceous of
Kansas (U.S.A.), and Specimens of Recent Forms, exhibited by
Dr. A. Smith Woodward, F.R.S., F.L.8., F.G.S., in illustration of
his paper.

Specimens of Igneous Rocks from Spring Cove, near Weston-super-
Mare, exhibited by W.S. Boulton, Esq., B.Sc., A.R.C.S., F.G.S., in
illustration of his paper.

February 3rd, 1904.

Sir Arcuipaty Grixte, D.C.L., D.Sc., Sec.R.S., Vice-President,
in the Chair.

Edward C. Banbery, Esq., Summerville, West Bank Avenue,
Lytham (Lancashire); William John Barnett, Esq., 35 Harley
Street, Cavendish Square, W.; Henry John Wolverton Brennand,
Ksq., B.A., M.B., F.C.S., 203 Macquarie Street, Sydney (N.S.W.) ;
Basil Elmsley Coke, Esq., 2nd Lieut. Royal Engineers, Elphinstone
Barracks, Plymouth; George Walter Grabham, Esq., B.A., Geolo-
gical Survey Office, 28 Jermyn Street, S.W.; Baird Halberstadt, Esq.,
Pottsville, Pennsylvania (U.S.A.); the Rev. Benjamin Oriel, B.Sc.,
2 First Avenue, Oldfield Park, Bath ; Robert Lionel Sherlock, Esq.,
B.Sc., Assoc.R.C.S., 186 Windleshaw Road, St. Helen’s; and
Andrew George Stenhouse, Esqg., Whitelee, Newhaven Road, Leith,
were elected Fellows of the Society. —

The List of Donations to the Library was read,

Vill - PROCEEDINGS OF THE GEOLOGICAL socrEty. {Feb. 1904.

The CHarrman read, for the second time, in accordance with
Sect. XI, Art. 8 of the Bye-Laws, the two letters addressed to the
Secretary (pp. Vi-vii); and notice was given of a Special General
Meeting to be held on February 24th, at 7.30 p.m.

The following communications were read :—

1. ‘On a Deep-Sea Deposit from an Artesian Boring at Kilacheri,
near Madras.’ By Prof. H. Narayana Rau, M.A., F.G.S.

2. ‘The Rhetic Beds of the South-Wales Direct Line.’ By
Prof. Sidney Hugh Reynolds, M.A., F.G.8., & Arthur Vaughan,
isg., (B-A., B:Se,.,.EG.8.

The following specimens, etc. were exhibited :—

Microscope-Sections of Radiolarian Rock from Kilacheri, exhibited
by Prof. H. Narayana Rau, M.A., F.G.S., in illustration of his
paper.

Photographs and Lantern-Slides, exhibited by Prof. S. H.
Reynolds, M.A., F.G.8., & A. Vaughan, Esq:, B.A., Bide. P:Gi5:
in illustration of their paper.

ANNUAL GENERAL MEETING,
February 19th, 1904.

Sir ArcaipaLp Gerxis, Sc.D., D.C.L., Sec.R.S., Vice-President,
in the Chair.

BrerorRE commencing the business of the Meeting, the CHarrmMan
read the following letter, which had been addressed to him by the
President :—

‘ Dear Sir ARCHIBALD, ‘February 9th, 1904,

‘ Please kindly convey to the Council, the Officers, and the Fellows of the
Geological Society my sincere regrets that 1 am not yet well enough to attend the
Anniversary Meeting, and personally thank them for the honour which they paid
me in making me their President, and for their unfailing goodness to me during my
tenure of office.

‘J shall also be grateful if you will congratulate on my behalf the new President
and the Recipients of Medals and Awards; and assure the Fellows of my constant
sympathy with, and faith in, the continued progress of the Society, and of my hope
tc be soon once more amongst them as a fellow-worker.

‘Thanking Mr. Teatr and yourself for your great kindness in taking over my
Presidential work tor me during my illness, and so relieving me of all responsibility,

‘I remain, dear Sir Archibald,
‘Sincerely yours,
‘Sir ARCHIBALD GEIKIE, D.C.L., Sec.R.S. CHARLES LAPWORTH.’

It was unanimously resolved that a telegram should be sent from
the Fellows in General Meeting assembled, thanking the President
for his message and wishing him a speedy restoration to health.

Report oF THE CounciL For 1903.

The Society continues to be in a generally-flourishing condition.
The Number of Fellows has undergone but little change: during
the past year 46 Fellows were elected (2 less than in 1902, and 6
less than in 1901), of whom 33 paid their Admission-Fees before
the end of the year. Moreover, 16 Fellows, who had been elected
in the previous year, paid their Admission-Fees in 1903, the total
accession of new Fellows during the past twelve months amounting
therefore to 49.

Deducting from this number a loss of 53 Fellows (30 by death,
13 by resignation, and 10 by remoyal from the List, under Bye-
Laws, Sect. VI, Art. 5), it will be seen that there is a decrease in

VOL, LX. b

x PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1904

the Number of Fellows of 4 (as compared with an increase of 6 in
1902, and a decrease of 4 in 1901).

This brings the total number of Fellows down to 1254, made up
as follows :—Compounders 287, Contributing Fellows 930 (exactly
the same number as in 1902), and Non-Contributing Fellows 37.

Turning now to the Lists of Foreign Members and Foreign
Correspondents, we have to deplore the loss of two of the former
in 1903 (Prof. J. P. Lesley and Prof. A. Renard). One Foreign
Correspondent also died (Herr F. Karrer). The vacancies thus
created (and one in the List of Foreign Correspondents left over
from 1902) were in part filled by the transfer of Prof. A. Penck
and Prof. A. Koch from the list of Correspondents to that of
Members, and by the election of Prof. C. Klein, and Dr. E. E. A.
Tietze as Foreign Correspondents. But there still remained on
December 31st, 1903, two vacancies in the list of Foreign Corre-
spondents.

With regard to the Income and Expenditure of the Society during
the past year, the figures set forth in detail in the Balance-Sheet
may be summarized as follows :—

The total Receipts, including the Balance of £61 7s. 8d. brought
forward from the previous year, amounted to £3003 Os, 9d., being
£75 14s. 11d. less than the estimated Income.

The total Expenditure during 1903 amounted to £2810 13s. 10d.,
being £206 14s. 2d. less than the estimated Expenditure for that

ear.
: The Estimates laid before the Fellows at the last Annual General
Meeting were exceeded chiefly in the case of the Library (£42 12s.5d.).
On the other hand, the Expenditure incurred in connexion with the
Museum-Catalogue was £37 15s. 3d. less,.and that incurred in
connexion with the Quarterly Journal was £229 2s. 1d. less, than
the estimated Expenditure.

During the past year the Council have had under consideration
certain suggested alterations in the method of selecting Papers
for Publication, and in the rules with regard to the admission of
Visitors to General Meetings. The result of these deliberations
will be laid before the Fellows at a Special General Meeting, to be
summoned at an early date.

The Council have to announce the completion of Vol. LIX and
the commencement of Vol. LX of the Society’s Quarterly Journal.

Reference is made in the Report of the Library-and-Museum
Committee to Mr. C. Davies Sherborn’s manuscript Card-Catalogue
of the Library. It is hoped that Fellows will make use of this
Catalogue for finding references to literature on the subjects of
their study. Mr. Sherborn has also undertaken to continue during
the current year the preparation of the catalogue-slips for the
International Catalogue of Scientific Literature.

Since Easter 1903, the state of health of the President has been
such as to preclude him from coming to London, to guide the
deliberations of the Council or to take the chair at the Evening
Meetings. These duties were undertaken ‘during three months of

Vol. 60.] ANNUAL REPORT. Xl

the past Session by Mr. Teall, and during so much of the present
Session as has now elapsed, by Sir Archibald Geikie. The Council
feel sure that the Fellows will join with them in the fervent hope
that Prof. Lapworth may be speedily restored to health, and that
he may soon be able again to take an active share in the proceedings
of the Society.

The first Award from the Daniel-Pidgeon Fund was made, on
May 27th, 1903, to Dr. Ernest Willington Skeats, who, having been
engaged in the investigation of coral-reef deposits, proposed to
visit the dolomite-districts of the Tyrol, and collect specimens for
analysis and microscopic study, in continuation of his previous
researches.

The following Awards of Medals and Funds have also been made
by the Council :—

The Wollaston Medal is awarded to Prof. Albert Heim,
For.Memb.G.S., in recognition of the value of his researches con-
cerning the mineral structure of the Earth, and more especially
of his contributions towards the elucidation of the structures of
mountain-masses in general, and the Alps in particular.

The Murchison Medal, together with a sum of Ten Guineas
from the Murchison Geological Fund, is awarded to Prof. George
Alexander Louis Lebour, M.A., M.Sc., in recognition of the im-
portance of his contributions to our knowledge of the Carboniferous
rocks of the North of England.

The Lyell Medal, together with a sum of Twenty-Five Pounds
from the Lyell Geological Fund, is awarded to Prof. Alfred Gabriel
Nathorst, For.Memb.G.S8., in recognition of his valuable work in
investigating the floras of the various geological periods.

The Balance of the Proceeds of the Wollaston Donation-Fund is
awarded to Miss Ethel Mary Reader Wood, M.Sc., as an acknow-
ledgment of the value of her contributions to the study of the
Graptolites and the rocks in which they occur, and to encourage
her in further research.

The Balance of the Proceeds of the Murchison Geological Fund
is awarded to Dr. Arthur Hutchinson, M.A., as an acknowledgment
of the ability of his memoirs on mineralogical subjects, and to
encourage him in further work.

A moiety of the Balance of the Proceeds of the Lyell Geological
Fund is awarded to Prof. Sidney Hugh Reynolds, M.A., in recog-
nition of the value of his contributions to our knowledge of the
Paleozoic rocks of Ireland, and the geology of the Bristol district
and to encourage him in further work.

The other moiety of the Balance of the Proceeds of the Lyell
Geological Fund is awarded to Dr. Charles Alfred Matley, as an
acknowledgment of the value of his work in elucidating the geology
of the Island of Anglesey, and to encourage him in further
researches.

A sum of Twenty Guineas from the Proceeds of the Barlow-
Jameson Fund is awarded to Mr. Hugh John Llewellyn Beadnell,
in recognition of his important memoirs on the topography and

b2

xl PROCEEDINGS OF THE GEOLOGICAL socieTy. [May 1904,

geology of the Oases and other districts of the Libyan Desert, and
of his valuable collections of vertebrate remains in Egypt during
the last three years, and to encourage him in further investigations,

Report oF THE LIBRARY-AND-Musretm CommirteEr For 1903.

The Additions made to the Library during the past twelve months
have fully maintained, both in number and interest, the standard of
former years.

During 1903 the Library received by donation 156 Volumes of
separately-published Works, 301 Pamphlets and detached Parts of
Works, 280 Volumes and 51 detached Parts of Serial Publications,
and 18 Volumes of Newspapers. ‘To these must be added 36 back
Volumes of the American journal ‘Science,’ presented by Prof.
Watts.

The total number of accessions to the Library by Donation is thus
found to amount to 490 Volumes, 301 Pamphlets, and 51 detached
Parts.

The number of Maps presented by various Donors is again very
considerable. No less than 179 Sheets of Maps were received,
106 of which came from the Ordnance-Survey Department.

Although the task of selection from among the numerous dona-
tions mentioned in the foregoing paragraphs is not unattended with
difficulty, your Committee may perhaps be allowed to direct special
attention to the following:—Dr. Tempest Anderson’s ‘ Volcanic
Studies’; Mr. Mellard Reade’s ‘ Evolution of Earth-Structure’; the
4th edition of Sir Archibald Geilkie’s ‘Text-Book of Geology’ (in two
volumes); M. de Lapparent’s ‘ Abrégé de Géologie’; M. P. H.
Fritel’s ‘ Paléontologie’; Prof. G. de Lorenzo’s work on the great
Pleistocene Lakes of Southern Italy; the first part of M. F.
Delafond’s work on the Coal-Measures and Permian of Blanzy and
Le Creusot ; the fourth part of Prof. Gosselet’s Geology of the
North of France ; ‘ Outlines of the Geology of Japan’ published by
the Government of that Empire; the Geological Survey Memoirs
on the Isle of Man, on North Arran and South Bute, on the Cheadle
Coalfield, and on the country around Leicester, Reading, Salisbury,
Chichester, Torquay, and Dublin; also the second volume of the
‘Cretaceous Rocks of England.’ Moreover, numerous publications
were received from the Geological Survey ‘and Mines Departments
of Canada, Newfoundland, Sean Scotia, British Columbia, Natal,
the Transvaal, the various ‘States of the Australian Commonwealth,
India, Egypt, the United States, Portugal, Austria-Hungary, Prussia,
Sweden, and Russia ; from the Imperial Department of Agriculture
for the West Indies; and from the French Ministry of Public
Works. <A copy of the voluminous Report on the Asphalt-Industry
of Trinidad was presented by the Colonial Office.

Vol. 60.] ANNUAL REPORT. Xlii

In addition to the Orduance-Survey maps mentioned in a pre-
ceding paragraph, 8 Sheets of Maps were received from the
‘Geological Survey of England and Wales ; and 21 Sheets from the
Geological Survey of Japan. Dr. Wheelton Hind and Mr. J. T.
Stobbs presented a copy of their ‘Chart of Fossil Shells found in
connexion with the Seams of Coal and Ironstone of North Staf-
fordshire.’

Sir John Evans presented a photogravure portrait of himself,
and Col. F. T. N. Spratt-Bowring, R.E., presented a framed portrait
of the late Admiral Spratt: these have been added to the Society’s
collection of Portraits of Eminent Geologists.

The preparation of aset of electrotype reproductions of the Medals
in the gift of the Council was entrusted to Mr. Frank Bowcher, the
designer of the Prestwich Medal, and these have now been framed
and may be inspected at the Society’s Apartments.

The Books, Maps, ete., enumerated above were the gift of 163
Personal Donors; 128 Government Departments and other Public
Bodies ; and 157 Societies and Editors of Periodicals.

The Purchases, made on the recommendation of the standing
Library Committee, included 63 Volumes and 11 Parts of separately-
published Works; 43 Volumes and 15 Parts of Works published
serially ; and 50 Sheets of Maps.

A set of the second series of photographs and the corresponding
lantern-slides, issued by the Geological Photographs Committee of
the British Association, was subscribed for, and is now deposited
in the Library.

The total Expenditure in connexion with the Library during the
past year was as follows :—

ea oe

Books, Periodicals, ete. purchased.......... 75 13 /

Binding of Books and Mounting of Maps.... 166 18 10

Total £242 12 5

or £42 12s. 5d. more than the sum set apart for these purposes in
the Estimates. This excess is largely due to the necessity of
overtaking certain arrears of binding which had accumulated
during recent years. |

The rearrangement of the Library authorized by the Council
has been in progress during the year, and excellent work has been
done by the Assistant-Clerk (Mr. Black) and the Junior Assistant
(Alec Field). The Assistant-Librarian (Mr. W. R. Jones), in the
meantime, has been engaged in making a current Card-Catalogue-
and in preparing the Map-Catalogue and the Record of Geological
Literature. Much, however, remains to be done before the arrange-
ment of the books and the binding can be considered as brought
thoroughly up to date. In this matter there is every reason to
believe that good progress will continue to be made in the current
year.

X1V PROCEEDINGS OF THE GEOLOGICAL Society. [May 1904,

Mr. C. Davies Sherborn supplies the following details with regard
to the progress of the new Card-Catalogue of the whole Library,
upon which he is engaged :—

‘The 1880 Catalogue has been mounted, cross-referenced, and arranged in
cabinets up to ‘“‘Humboldt”; and all “Serials,” ‘“ Academies,” ‘ Surveys,”
“Reports,” etc. included therein have been also roughly sorted into cabinets.
This statement applies also to the “Additions made to the Library” from
1880 to 1888. It will be impossible to press-mark the cards until further
progress is made; but the subject- and locality-cards should already be of
considerable utility, as, for example, “‘ Caves,” “ Vesuvius,” “ Gold,” ete.’

Musrvum.

Messrs. J. F. Walker & G. W. Lamplugh presented a series of
Fossil Brachiopoda from the fossiliferous band at the top ct the
Lower Greensand at Shenley Hill, near Leighton Buzzard, figured
in Plates XVI-XVIII, Quart. Journ. Geol. Soc. Vol. LIX (1903),
which illustrate the paper dealing with the above-mentioned
stratum.

A specimen of the Volcanic Ash which fell in Barbados, asa
result of the eruption of the St. Vincent Soufricre, on March 22nd,
1903, was presented by Sir Daniel Morris, K.C.M.G., Imperial
Commissioner of Agriculture for the West Indies.

For the purpose of study and comparison the Collections were
visited on 34 occasions during the year, the contents of about
63 drawers (from 43 cabinets) being thus examined. Moreover,
the permission of the Council having been duly obtained, about
122 specimens were lent to various investigators.

No expenditure, beyond that involved in the publication of the
Museum-Catalogue, was incurred in connexion with the Museum
during the year 1903.

The appended Lists contain the Names of Government Depart-
ments, Public Bodies, Societies, Editors, and Personal Donors, from
whom Donations to the Library have been received during the year
under review :—

I. GoveRNMENT DEPARTMENTS AND OTHER PuBLic Boptks.

American Museum of Natural History. New York.
Athens.—Observatoire National d’Athénes.
Australian Museum. Sydney (New South Wales).
Austria.—Kaiserlich-K6énigliche Geologische Reichsanstalt. Vienna.
Kaiserlich-Konigliches Naturhistorisches Hofmuseum. Vienna.
Bavaria.—Konigliches Bayerisches Oberbergamt. Munich.
Belgium.—Académie Royale des Sciences, des Lettres & des Beaux-Arts de
Belgique. Brussels.

Musée Royal d’Histoire Naturelle. Brussels.
Berlin.—Ko6nigliche Preussische Akademie der Wissenschaften.
Birmingham, University of.

Vol. 60. } ANNUAL REPORT. xV

Bohemia.—Royal Museum of Natural History. Prague.

. Naturwissenschaftliche Landesdurchforschung. Prague.

British Columbia.—Department of Mines, Victoria (B.C.).

Bureau of Provincial Information, Victoria (B.C.).

British Guiana.—Department of Mines. Georgetown.

British South Africa Company. London.

California University. Berkeley (Cal.).

Cambridge (Mass.)—Museum of Comparative Zoology, Harvard College.

Canada.—Geological & Natural History Survey. Ottawa.

—, High Commissioner for. London.

Cape Colony.—Department of Agriculture: Geological Commission. Cape
Town.

Chicago, University of.

‘ Field’ Columbian Museum.

Christiania, University of.

Denmark.—Danmarks Geologiske Underségelse. Copenhagen.

Kongelige Danske Videnskabernes Selskab. Copenhagen.

Dijon.—Académie des Sciences, des Arts & des Belles Lettres.

Dublin.—Royal Irish Academy.

Egypt.—Department of Public Works: Geological Survey. Cairo.

Finland.—Finlands Geologiska Undersékning. Helsingfors.

France.—Dépét de la Marine. Paris.

Ministére des Travaux Publics. Paris.

Muséum d’Histoire Naturelle. Paris.

Germany.—Kaiserliche Leopoldinisch-Carolinische Deutsche Akademie der
Naturforscher. Halle an der Saale.

Great Britain—Army Medical Department. London.

British Museum (Natural History). London.

—. Colonial Office. London.

—. Geological Survey. London.

—. Home Office. London.

—. India Office. London.

—. Ordnance Survey. Southampton.

Holland.—Departement van Kolonien. The Hague.

Hull.—Municipal Museum.

Hungary.—Kéonigliche Ungarische Geologische Anstalt (Magyar Féldtani
Tarsulat). Budapest.

India.— Geological Survey. 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.

London.—City of London College.

—. Patent-Office Library.

—. Royal College of Surgeons.

—. University College.

Maryland Geological Survey. Baltimore (Md.).

Metz.—Académie des Lettres, Sciences, Arts & Agriculture.

Mexico.—Instituto Geologico. Mexico City.

Michigan College of Mines. Houghton (Mich.).

Milan.—Reale Istituto Lombardo di Scienze & Lettere.

Montana University. Missoula (Mont.).

Munich.—K@6nigliche Bayerische Akademie der Wissenschaften.

Mysore Geological Department. Bangalore.

Nancy.—Académie de Stanislas.

Natal.—Department of Mines. Pietermaritzburg.

Nebraska.—Geological Survey. Lincoln (Neb.).

Newfoundland.—Geological Survey. St. John’s (N.F.).

New Jersey Geological Survey. Trenton (N.J.).

New South Wales, Agent-General for. London.

Department of Lands. Sydney.

—. Department of Mines & Agriculture. Sydney.

xv PROCEEDINGS OF THE GEOLOGICAL sociETY. [May 1904,

New South Wales.—Geological Survey. Sydney.

New York Museum. Albany (N.Y.).

New Zealand.—Department of Mines. Wellington.

Norway.—Geologiske Underségelse. Christiania.

Nova Scotia, Agent-General for. London.

Department of Mines. Halifax (N.S.).

Padua.—Reale Accademia di Scienze, Lettere & Arti.

Paris—— Académie des Sciences.

Perak Government. Taiping.

Peru.—Ministerio de Fomento. Lima.

Pisa, Royal University of.

Portugal.—Commiss4o dos Trabalhos geologicos. Lisbon.

Prussia.—Ministerium fiir Handel & Gewerbe. Berlin.

K6nigliche Preussische Geologische Landesanstalt. Berlin.

Queensland, Agent-General for. London.

——. Department of Mines. Brisbane.

Geological Survey. Brisbane.

Redruth School of Mines.

Rhodesian Museum. Bulawayo.

Rome.—Reale Accademia dei Lincei.

Russia.—Comité Géologique. St. Petersburg.

Section Géologique du Cabinet de S.M. ?Empereur. St. Petersburg.

South Australia, Agent-General for. London,

——. Geological Survey. Adelaide.

School of Mines & Industries. Adelaide.

South Wales & Monmouthshire, University College of. Cardiff.

Spain.—Comision del Mapa Geoldégico. Madrid.

St. Petersburg.—Académie Impériale des Sciences.

Stockholm.—Kongliga Svenska Vetenskaps Akademi.

Sweden.—Sveriges Geologiska Undersékning. Stockholm.

Switzerland.—Geologische Kommission der Schweiz. Berne.

Tasmania.—Secretary for Mines. Hobart.

Tokio, Imperial University of.

College of Science.

Toronto, University of.

Transvaal Mines Department. Pretoria.

Turin.—Reale Accademia delle Scienze.

United States Geological Survey. Washington (D.C.).

Department of Agriculture. Washington (D.C.).

National Museum. Washington (D.C.).

Upsala, University of.

Mineralogical & Geological Institute.

Victoria (Austral.), Agent-General for. London.

—— (——). Department of Mines. Melbourne.

Vienna.—Kaiserliche Akademie der Wissenschaften.

Washington, State of (U.S.A.).—Geological Survey. Tacoma (Wash.).

(D.C.).—Smithsonian Institute.

West Indies, ka Agricultural Department for the. Bridgetown (Bar-
bados).

Western Australia, Agent-General for. London.

——. Department of Lands. Perth (W.A.).

——. Department of Mines. Perth (W.A.).

—. Geological Survey. Perth (W.A.).

—. Victoria Public Library. Perth (W.A.).

Wisconsin.—Geological & Natural History Survey. Madison (Wisc.).

II. Socterres anp Eprirors.

Adelaide.—Royal Society of South Australia.

Alnwick.—Berwickshire Naturalists’ Club.

Bahia.—Instituto Geographico & Historico.

Barnsley.— Midland Institute of Mining, Civil, & Mechanical Engineers.
Basel.—Naturforschende Gesellschaft.

Bath.—Natural History & Antiquarian Field-Club.

Vol. 60. } ANNUAL REPORT. XVll

Belfast.—Natural History & Philosophical Society.

Berlin.—Deutsche Geologische Gesellschaft.

Gesellschaft Naturforschender Freunde.

—. ‘Zeitschrift fiir Praktische Geologie.’

Berne.—Schweizerische Naturforschende Gesellschaft.

Bordeaux.—Société Linnéenne.

Boston (Mass.) Society of Natural History.

Boston (Mass.).—American Academy of Arts & Sciences.

Brooklyn (N.Y.) Institute of Arts & Sciences.

Brunswick.—Verein fiir Naturwissenschaft zu Braunschweig.

Brussels.—Société Belge de Géologie, de Paléontologie & d’Hydrologie.

Société Malacologique de Belgique.

Budapest.—Féldtani Kézlény.

Buenos Aires.—Instituto Geografico Argentino.

—. Sociedad Cientifica Argentina.

Buffalo (N.Y.) Society of Natural Sciences.

Caen.—Société Linnéenne de Normandie.

Caleutta.—‘ Indian Engineering.’

—. Asiatic Society of Bengal.

Cambridge.—Philosophical Society.

Cape Town.—South African Philosophical Society.

Cardiff—South Wales Institute of Engineers.

Chicago.— Journal of Geology.’

Christiania.—‘ Nyt Magazin for Naturvidenskaberne.’

Colorado Springs.—‘ Colorado College Studies.’

Copenhagen.—Dansk Geologisk Forening.

Cérdoba (Argentine Republic)—Academia Nacional de Ciencias.

Cracow.—Académie des Sciences (Akademia Umiejetnosci).

Croydon Microscopical & Natural History Society.

Darmstadt.—Verein fiir Erdkunde.

Douglas.—Isle-of-Man Natural History & Antiquarian Society.

Dresden.—Naturwissenschaftliche Gesellschaft.

——. Verein fiir Erdkunde.

Edinburgh.—Royal Physical 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.
Geneva.—Société Physique & d’Histoire Naturelle.

Genoa.—Giornale di Geologia pratica.

Giessen.—Oberhessische Gesellschaft fiir Natur- & Heilkunde.
Gloucester—Cotteswold Naturalists’ Field-Club.
Gratz.—Naturwissenschaftlicher Verein fiir Steiermark.
Haarlem.—Société Hollandaise des Sciences.

Halifax (N.S.).—Nova Scotian Institute of Science.
Helsingfors.—Geografiska Férening i Finland.

- ——. Meddelanden fran Industristyrelsen i Finland.
Hereford.— W oolhope Naturalists’ Field-Club.
Hertford.—Hertfordshire Natural History Society.
Hobart.—Royal Society of Tasmania.

Hull Scientific & Field-Naturalists’ Club.

Kiev.—Société des Naturalistes.

Lausanne.—Société Vaudoise des Sciences Naturelles.
Lawrence.—‘ Kansas University Bulletin.’
Leeds.—Yorkshire Geological & Polytechnic Society.
Leicester Literary & Philosophical Society.

Leipzig.—‘ Zeitschrift fiir Krystallographie & Mineralogie.’
Liége.—Société Géologique de Belgique.

Société Royale des Sciences.

Lille.—Société Géologique du Nord.

Lima.— Revista de Ciencias.’

—. Sociedad geografica.

Lisbon.—Sociedade de Geographia.

Liverpool Geological Society.

——. «Literary & Philosophical Society.

XVill PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

London.—‘ The Academy.’
‘The Atheneum.’
British Association for the Advancement of Science.
British Association of Waterworks Engineers.
‘The Chemical News.’
Chemical Society.
‘The Colliery Guardian.’
East India Association.
‘The Geological Magazine.’
Geologists’ Association.
Institution of Civil Engineers.
Institution of Mining & Metallurgy.
Tron & Steel Institute.
‘The Iron & Steei Trades’ Journal.’
‘Knowledge.’
Linnean Society.
‘The London, Edinburgh, & Dublin Philosophical Magazine.’
Mineralogical Society.
‘ Nature.’
Paleontographical Society.
‘The Quarry.’
Royal Agricultural Society.
Royal Geographical Society.
Royal Institution.
Royal Meteorological Society.
Royal Microscopical Society.
Royal Photographic Society of Great Britain.
Royal Society.
Society of Arts.
Society of Biblical Archeology.
‘The South-Eastern Naturalist’ (S.E. Union of Scientific Societies).
Victoria Institute.
* Water.’
. Zoological Society.
Manchester Geological Society.
Literary & Philosophical Society.
Melbourne.—Australasian Institute of Mining Engineers.
Royal Society of Victoria.
. 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.—Institution of Mining Engineers.
North-of-England Institute of Mining & Mechanical Engineers.
. Northampton.—Northamptonshire Natural History Society.
Ottawa.—Royal Society of Canada.
Paris.—Commission Frangaise des Glaciers.
Société Francaise de Minéralogie.
Société Géologique de France.
Penzance.—Royal Geological Society of Cornwall.
Perth.—Perthshire Society of Natural Science.
Philadelphia.—Academy of Natural Sciences.
American Philosophical Society.
Pisa.—Societa Toscana di Scienze Naturali.
Plymouth.—Devonshire Association for the Advancement of Science.
Rennes.—Société Scientifique & Médicale de Ouest.
Rochester (N.Y.).—Geological Society of America.
Rome.—Societa Geologica Italiana.
Rugby School Natural History Society.
Santiago de Chile——Sociedad Nacional de Mineria.
Société Scientifique du Chili.
Scranton (Pa.).—* Mines & Minerals.’
St. Petersburg.—Russische Kaiserliche Mineralogische Gesellschaft.
—. Société Impériale des Naturalistes.
Stockholm.—Geologiska Foérening.

DUC CPSEBRAABRDERB ERNE AGEL

Vol. 60. ]

Stuttgart.—

ANNUAL REPORT.

—‘ Centralblatt fiir Mineralogie, Geologie & Palaontologie.’
‘Neues Jahrbuch fiir Mineralogie, Geologie & Palaontologie.’
Oberrheinischer Geologischer Verein.

—. Verein fiir Vaterlandische Naturkunde in W iirttemberg.

———
-

* Zeitschrift fiir 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.— Berg- & Hiittenminnisches Jahrbuch.’
Kaiserlich-K6nigliche Zoologisch-Botanische Gesellschaft.

Washington (D.C.).—Academy of Sciences.

Biological Society.

Wellington (N.Z.).—New Zealand Institute.

Wiesbaden.—Nassauischer Verein fiir Naturkunde.

York.—Yorkshire Philosophical Society.

Adams, F. D.
Ameghino, F.
Ami, H. M.
Anderson, T.
Arber, E. A. N.
Arctowski, H.

Barré, O.
Bascom

:
Beecher, C. E. (the late).

Bistram, A. von.

Blake, the Rev. J. F.

Blake, W. P.
Blanckenhorn, M.
Bonney, T. G.
Borredon, G.
Bourcart, E.
Brown, H. Y. L.

Brown, J. A. (the late).
Bullen, the Rev. R. A.

Bush, L. P.

Cadell, H. M.
Carez, L.
Cayeux, L.
Chapman, F.
Choffat, P.
Clark, J. E.
Cole, G. A. J.
Collins, J. H.

Cooméraswamy, A. K.

Cordovey, M.
Credner, H.
Cumings, E. R.

Dall, W. H.
Davis, W. M.
Dervis, V.
Dewalque, G.
Dollfus, G. F.
Dupare, L.

Eaton, G. F.
Emmons, S. F.
Evans, Sir John.

III. Prrsonart Donors.

Fouqué, F. (the late).

Fox, H.
Fritel, P. H.
Fritsch, A.

Garwood, E. J.
Gaudry, A

Geikie Sir Archibald.

Gilpin, E., jun.
Gordon, M. M. O.
Gosselet, J.
Grayson, H. J.
Guppy, R. J. L.

Hamilton, A.
Hamling, J. G.
Hargreaves, T. S.

Harmer, F. W.
Hatch, F. H.
Hawell, the Rev. J.
Herz, O.

Hill, the Rev. E.
Hind, W.

Hoek, H.

Holland, T. H.
Holmes, T. V.
Hopkinson, J.
Hovey, E. O.
Howley, J. P.
Hudleston, W. H.
Hull, E.

Hutton, he
Issel, A.

Jentzsch, A.
Jones, T. R.
Jordan, H. K.

Kaleesinski, A. von.
Kewitsch, —.
Kirsopp, J., jun.
Koch, A.

Keenen, A. von.
Kriz, M.

Lacroix, A.
Lambe, L. M.
Lambert, J.
Lamplugh, G. W.
Lapparent, A. de.
Lebour, G. A.
Liebisch, Th.
Lobley, J. L.
Lomas, J.

Longe, F. D.
Lorenzo, G. de.
Louis, D. A.
Lupsa, I. F.
Lyman, B.S.

Manck, A. V.
Manson, M.
Marbut, C. F.
Marr, J. E.
Meli, R.
Mennell, F. P.
Meunier, St.

Mojsisovics, E. von.

Monckton, H. W.
Morris, Sir Daniel.
Mourlon, M
Mrazec, L.
Miller, E. C.

Nares, Sir George.

‘ Newton, E. T

Newton, R. B.

Pachundaki, D. E.
Packard, A. S.
Parkinson, H.
Parkinson, J.
Pauw, L. F. de.
Pearce, F.

Perner, J.

Prinz, W.

Reade, T. M.
Renevier, E.

X1x

Richthofen, Baron F. von.

xX

Rigaux, E.
Rowe, A. W.

Sacco, F.
Sauvage, H. E.
Sawyer, A. R.
Schardt, H.
Schopp, H.
Seward, A. C.
Shaw, F. G.
Sheppard, T.
Sherborn, C. D.

Shoolbred, J. N.

Skeats, E. W.
Small, E. W.
Somervail, A.

|
|
|
|
|
|
|

{

PROCEEDINGS OF THE GEOLOGICAL SOCIETY.

Spratt-Bowring, F. T. N.
Steinmann, G.

Stephens, T.

Stobbs, J. T.

Stromeyer, C. E.

Talbot, M.
Thomson, A. G. M.
Thompson, B.
Thoulet, J.
Thresh, J. C.
Toula, F.
Traquair, R. H.
Twelvetrees, W. H.

Uhh, V.

Vaughan, A.
Vidal, L. M.

Walker, J. F.
Watts, W. W.
Whitaker, W.
Willis, B.
Wiltshire, E. W.
Woodward, A. S.
Woodward, H.
Woodward, H. B.
Worth, R. H.

Zeiller, R.

[May 1904,

Vol. 60. | ANNUAL REPORT,

Xxl

CoMPARATIVE STATEMENT OF THE NUMBER OF THE SOCIETY AT THE

CLosE oF THE YEARS 1902 anv 19038.

Dee. 31st, 1902. Dee. 3lst, 1905.
Mempounders .;.....!.... a | ea ers 2 287
Contributing Fellows...... EN aos grt ae 930
Non-contributing Fellows. . Ee bh ott Siw weave 37
1258 1254
Foreign Members ........ AD AM te sc0ag ey 40
Foreign Correspondents... . Seg Sesaie 38
1337 1332

Comparative Statement, explanatory of the Alterations in

the Number

of Fellows, Foreign Members, and Foreign Correspondents at the

close of the years 1902 and 1903.

Number of Compounders, Contributing and Non- )
contributing Fellows, December 31st, 1902 .. f

Add Fellows elected during the former year and
paid in 1903

Add Fellows elected and paid in 1903

a) 2) & Sep) Sie. © fb gE foe Oo 6, ee BB 8, Bl eRe

Deduct Compounders deceased................
Contributing Fellows deceased ..........
Non-contributing Fellows deceased
Contributing Fellows resigned
Contributing Fellows removed

Number of Foreign Members and Foreign Cor- 9

respondents, December 31st, 1902
Deduct Foreign Members deceased ......., 2
Foreign Correspondents deceased

OS) 8) ee) eye one.g) ©

Foreign . Correspondents elected 2
Foreman Members ..........<

Add Foreign Members elected .......... 2

Foreign Correspondents elected 2

1258

16

33

1307
fi
21
2
13
10

— 353

1254
i)
74
+

— 78

XX1l PROCEEDINGS OF THE GEOLOGICAL socieTY. [May 1904,

DEcEASED FELLows.

Compounders (7).
Bell, M., Esq. | Justen, F. W., Esq.
Corfield, Prof. W. H. | Mason, J., Esq.
Gatty, Dr. C. H. | Vicary, W., Esq.
Hutchinson, Maj.-Gen. A. H. |

Resident and other Contributing Fellows (21).

Aveline, W. T., Esq. | Jennings, A. V., Esq.
Barnes, J. H., Esq. Mellors, P., Esq.
Brown, J. A., Esq. _ Nicholson, Sir Charles.
Carter, J., Esq. | Perey, C. M., Esq.
Close, the Rev. M. H. | Pirbright, Lord.
Collins, A. L., Esq. | Poppleton, BR. D., Esq.
Crick, W. D., Esq. | Powell, J. H., Esq.
Etheridge, R., Esq. - Thomas, W., Esq.
Exton, Dr. H. Ward, T., Esq.
Griffith, N. R., Esq. | Winbolt, J. 8., Esq.

Haughton, T. J., Esq. |
Non-contributing Fellows (2).
Gavey, G. E., Esq. | Whinfield, E. W., Esq.

Deceased Foreign MEMBERs (2).
Lesley, Prof. J.P. | Renard, Prof. A.

DecEaseD Forergn CorrEsPonDENT (1).
Karrer, Herr F.

Fetitows Restenep (13).

Bates, T. L., Esq. Parkinson, James, Esq.
Edwards, W. B. D., Esq. | Percival, Dr. G.

Goss, H., Esq. | Pilling, the Rev. S.
Hay, R., Esq. _ Platnauer, H. M., Esq.
Leach, R. E., Esq. Pruen, J. A., Esq.
Lewis, G., Esq. | Solly, R. H., Esq.

Parker, H., Esq.

Fettows Removep (10),

Bainbridge, C. E., Esq. Derasari, D. P., Esq.
Bilgrami, Syed Ah. Maclean, H., Esq.
Barr, W: 1. G.,. Hsq. Smith, W. H., Esq.
Cheadle, W. W., Esq. Streeten, F. E., Esq.

Davies, H., Esq. | Waterman, W. J., Esq.

Vol. 60. | ANNUAL REPORT. XXill

The following Personages were elected Foreign Members during the
year 1903 :—

Prof. Albrecht Penck, of Vienna.
Prof. Anton Koch, of Budapest.

The following Personages were elected Foreign Correspondents during
the year 1903 :—

Prof. Carl Klein, of Berlin.
Dr. Emil Ernst August Tietze, of Vienna.

After the Reports had been read, it was resolved :—

That they be received and entered on the Minutes of the Meeting,
and that such parts of them as the Council shall think fit be printed
and circulated among the Fellows.

It was afterwards resolved :—

That the thanks of the Society be given to Prof. Charles Lapworth,
retiring from the office of President.

That the thanks of the Society be given to Prof. H. A. Miers and
Mr. J. J. H. Teall, retiring from the office of Vice-President.

That the thanks of the Society be given to Dr. R. Logan Jack,
Lieut.-Gen. C. A. M*Mahon, Prof. H. G. Seeley, Prof. W. J. Sollas,
and Mr. J. J. H. Teall, retiring from the Council.

That the thanks of the Society be given to Mr. J. J. H. Teall
and Sir Archibald Geikie, Vice-Presidents, for having successively
fulfilled the duties of the President during his long rad

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
year :—

XXIV

PROCEEDINGS OF THE GEOLOGICAL soclETY. [May 1904,

OFFICERS AND COUNCIL.—1904.

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

VICE-PRESIDENTS.

Prof. Thomas George Bonney, Se.D., LL.D., F.R.S., F.S.A.
Sir Archibald Geikie, Sc.D., D.C.L., LL.D., Sec.R.S.
Edwin Tulley Newton, Esq., F.R.S.

Horace Bolingbroke Woodward, Esq., F.R.S.

SECRETARIES.

Robert Stansfield Herries, Esq., M.A.
Prof. William Whitehead Watts, M.A., M.Sc.

FOREIGN SECRETARY.
Sir John Evans, K.C.B., D.C.L., LL.D., F.R.S., F.L.S.

TREASURER.
William Thomas Blanford, C.I.E., LL.D., F.R.S.

COUNCIL.

The Rt. Hon. the Lord Avebury, |
eC Cat. LIne FS ards:

Francis Arthur Bather, M.A., D.Sc.

William Thomas Blanford, C.I.E.,
TED, ERS:

Prof. Thomas George Bonney, Sc.D., |

SON. Ss, BISA.

Sire ohn vans, K-C.B. DC,
iD. RS.

Prof. Edmund Johnstone Garwood,

A.
Sir Archibald Geikie, Sc.D., D.C.L.,
LL.D., Sec.R.S.
Prof. Theodore Thomas Groom, M.A.,
D.Se.
Alfred Harker, Esq., M.A., F.R.S.
Robert Stansfield Herries, Esq., M.A.
Prof. John Wesley Judd, C.B., D.Sc.,

LL.D. - ERS.

Percy Fry Kendall, Esq.

Philip Lake, Esq., M.A.

Prof. Charles Lapworth,
Ro:

Bedford McNeill, Esq., Assoc.R.S.M.

John Edward Marr, Sc.D., F.R.8.

Prof. Henry Alexander Miers, M.A.,
ERS.

Horace Woollaston Monckton, Esq.,
Pais.

Edwin
F.R.S.

| George Thurland Prior, Esq., M.A.

| Prof. William Whitehead Watts,

[Pegi Boreal Se

|The Rey. Henry Hoyte Winwood,

ea MA

_ Horace Bolingbroke Woodward, Esq.,

LEDS

Tulley Newton, EKsq.,

| ARLES,

Vol. 60. | ANNUAL REPORT. XXV

LIST OF
THE FOREIGN MEMBERS

OF THE GEOLOGICAL SOCIETY OF LONDON, 1n 1903.

Date of
Election,

1874. Prof. Albert Jean Gaudry, Paris.

1877. Prof. Eduard Suess, Vienna.

1880. Prof. Gustave Dewalque, Liége.

1880. Prof. Ferdinand Zirkel, Lewpzig.

1884. Commendatore Prof. G. Capellini, Bologna.

1885. Prof. Jules Gosselet, Lille.

1886. Prof. Gustav Tschermak, Vienna.

1887. Prof. J. P. Lesley, Philadelphia, Pa. (US.A.). (Deceased.)
1888. Prof. Eugéne Renevier, Lausanne.

1888. Baron Ferdinand von Richthofen, Berlin.

1889. Prof. Ferdinand A. Fouqué, Paris. (Deceased.)

1889. Geheimrath Prof. Karl Alfred von Zittel, Manich. (Deceased.)
1890. Geheimrath Prof. Heinrich Rosenbusch, Hezdelbery.

1891. Prof. Charles Barrois, Zile.

1893. Prof. Waldemar Christofer Broegger, Christiania.

1893. M. Auguste Michel-Lévy, Paris.

1895. Dr. Edmund Mojsisovics von Mojsvar, Vienna.

1898. Prof. Alfred Gabriel Nathorst, Stockholm.

1894. Prof. George J. Brush, New Haven, Conn. (U.S.A.).
1894. Prof. Edward Salisbury Dana, Wew Haven, Conn. (US.A.).
1894. Prof. Alphonse Renard, Ghent. (Deceased.)

1895. Prof. Grove Karl Gilbert, Washington, D.C. (U.S.A.).
1895. Dr. Friedrich Schmidt, S¢. Petersburg.

1896. Prof. Albert Heim, Ziirich.

1897. M. E. Dupont, Brussels.

1897. Dr. Anton Fritsch, Prague.

1897. Prof. Albert de Lapparent, Paris.

1897. Dr. Hans Reusch, Christiania.

1898. Geheimrath Prof. Hermann Credner, Leipzig.

1898. Mr. Charles Doolittle Walcott, Washington, D.C. (U.S. A.),
1899. Prof. Marcel Bertrand, Paris.

1899. Senhor Joaquim Felipe Nery Delgado, Lisbon,

1899. Prof. Emmanuel 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, Paris.

1900. Prof. Paul Groth, Munich.

1900. Dr. Sven Leonhard Tcernquist, Zend.

1901. Dr. Alexander Petrovich Karpinsky, St. Petersburg.

1901. Prof. Alfred Lacroix, Paris.

1903. Prof. Albrecht Penck, Vienna.

1903. Prof. Anton Koch, Budapest.

VOL. LX. C

s

XXV1 PROCEEDINGS OF THE GEOLOGICAL sociErTy. [May 1904,
LIST OF

THE FOREIGN CORRESPONDENTS

OF THE GEOLOGICAL SOCIETY OF LONDON, rw 1903.

Date of
Election.

1866. Prof. Victor Raulin, Montfaucon d’ Argonne.

1874, Prof. Igino Cocchi, Florence.

1879. Dr. Emile Sauvage, Boulogne-sur-Mer.

1889. M. R. D. M. Verbeek, Buctenzory, Java.

1890. Herr Felix Karrer, Vienna. (Deceased.)

1890. Prof. Adolph von Koenen, Gottingen.

1892. Prof. Johann Lehmann, Kel.

1893. Prof. Aléxis Pavlow, Moscow.

1893. M. Ed. Rigaux, Boulogne-sur-Mer.

1894, Prof. Joseph Paxson Iddings, Chicago, Ill. (U.S.A.).

1894. M. Perceval de Loriol-Lefort, Campagne Frontenex, Geneva.

1894, Dr. Francisco P. Moreno, La Plata.

1894, Prof. August Rothpletz, Munich.

1894. Prof. J. H. L. Vogt, Christiania.

1895. Prof. Konstantin de Kroustchoff, S¢. Petersburg.

1896. Prof. S. L. Penfield, New Haven, Conn. (U.S.A.).

1896, Prof. Johannes Walther, Jena.

1897. M. Louis Dollo, Brussels.

1897. M. Emmanuel de Margerie, Paris.

1897. Prof. Count H. zu Solms-Laubach, Strasburg.

1898. Dr. Marcellin Boule, Paris.

1898. Dr. W. H. Dall, Washington, D.C. (U.S.A.).

1899. Prof. Charles Emerson Beecher, New Haven, Conn. (U.S.A.).
(Deceased. )

1899. Dr. Gerhard Holm, Stockholm.

1899. Prof. Theodor Liebisch, Gottingen.

1899. Prof, Franz Loewinson-Lessing, St. Petersburg.

1899. M. Michel I. Mourlon, Brussels.

1899. Prof. Henry Fairfield Osborn, New York (U.S.A.).

1899. Prof. Gregorio Stefanescu, Bucharest.

1899. Prof. René Zeiller, Paris.

1900. Prof. Arturo Issel, Genou.

1900. Prof. Ernst Koken, 7vbingen.

1900. Prof. Federico Sacco, Turin.

1901. Prof. Friedrich Johann Becke, Vienna.

1902. Prof. Thomas Chrowder Chamberlin, Chicago, Iil. ( CASA. yi

1902. Dr. Thervaldr Thoroddsen, Copenhagen.

1902. Prof. Samuel Wendell Williston, Chicago, Ill. (U.S.A.).

1903. Prof. Carl Klein, Berlin.

1903. Dr. Emil Ernst August Tietze, Veenna.

Vol. 60. | ANNUAL REPORT. XXV1
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 tu
enable the Council of the Geological Society to reward those individuals of any
country by whom such researches may hereafter be made,’—‘ such individual not
being a Member of the Council.’

1831. Mr. William Smith.
1835. Dr. G. A. Mantell.

1869. Dr. Henry C. Sorby.
1870. Prof. G. P. Deshayes.

1836. M. Louis Agassiz. 1871. Sir Andrew Ramsay.
1837, age T. P. Cautley. 1872. Prof. James D. Dana.

Dr. H. Falconer. 1873. Sir P. de M. Grey Egerton.
1838. Sir Richard Owen. 1874. Prof. Oswald Heer.
1839. Prof. C. G. Ehrenberg. 1875. Prof. L. G. de Koninck.
1840. Prof. A. H. Dumont. 1876. Prof. Thomas H. Huxley.
1841. M. Adolphe T. Brongniart. 1877. Mr. Robert Mallet.
1842. Baron L. von Buch. 1878. Dr. Thomas Wright.
1843. M. Elie de Beaumont. 1879. Prof. Bernhard Studer.

M. P. A. Dufrénoy. 1880. Prof. Auguste Daubrée.
1844. The Rey. W. D. Conybeare. | 1881. Prof. P. Martin Duncan.
1845. Prof. John Phillips. | 1882. Dr. Franz Ritter von Hauer.
1846. Mr. William Lonsdale. 1883, Dr. William Thomas
1847. Dr. Ami Boué. | Blanford.
1848. The Very Rev. W. Buckland. | 1884. Prof. Albert Jean Gaudry.
1849, Sir Joseph Prestwich. 1885. Mr. George Busk.
1850. Mr. William Hopkins. 1886. Prof, A.L.0. Des Cloizeaux.
1851. The Rey. Prof. A. Sedgwick.) 1887. Mr. John Whitaker Hulke.
1852. Dr. W. H. Fitton. 1888. Mr. Henry B. Medlicott.
1853, M. le Vicomte A. d’Archiac. | 1889. Prof.Thomas George Bonney.

M. E. de Verneuil. | 1890. Prof. W. C. Williamson.
1854. Sir Richard Griffith. 1891. Prof. John Wesley Judd.
1855. Sir Henry De la Beche. | 1892. Baron Ferdinand = yon
1856, Sir William Logan. | tichthofen.
1857. M. Joachim Barrande. 1893. Prof. Nevil Story Maskelyne.

P Herr Hermann von Meyer, 1894. Prof. Karl Alfred von Zittel.

1858. } prof. James Hall. 1895. Sir Archibald Geikie.
1859. Mr. Charles Darwin. | 1896. Prof. Eduard Suess.
1860, Mr. Searles V. Wood. 1897. Mr. Wilfrid H. Hudleston.
1861. Prof. Dr. H. G. Bronn. | 1898. Prof. Ferdinand Zirkel.
1862. Mr. R. A.C. Godwin-Austen. | 1899. Prof. Charles Lapworth.
1863. Prof. Gustav Bischof. / 1900. Prof. Grove Karl Gilbert.
1864. Sir Roderick Murchison. | 1901. Prof. Charles Barrois.
1865. Dr. Thomas Davidson. 1902. Dr. Friedrich Schmidt.
1866. Sir Charles Lyell. _ |. 1903. Prof. Heinrich Rosenbusch.
1867. Mr. G. Poulett Scrope. | 1904. Prof. Albert Heim.

1868. Prof. Carl F. Naumann.

c2

XXVIli

AWARDS

PROCEEDINGS OF THE GEOLOGICAL SOCIETY.

OF THE

[May 1904,

BALANCE OF THE PROCEEDS OF THE WOLLASTON

1831.
1833.
1854.
1835.
1836.
1838.
1839.
1840.
1841.
1842.
1845.
1844.
1845.
1846.
1847.
1848.
1849.
1850.
1851.
1852.
1855.
1854.
1855.
1856.
1857.
1858.
1859.

1860.

1861.
1862.
1853.
1864.
1865.
1866.
1867.
1868.

‘DONATION FUND.’
Mr. William Smith. — 1869. Mr. William Carruthers.
Mr. William Lonsdale. 1870. M. Marie Rouault.
M. Louis Agassiz. 1871. Mr. Robert Etheridge.
Dr. G. A. Manteli. 1872. Dr. James Croll.

Prof. G. P. Deshayes.
Sir Richard Owen.

Prof. C. G. Ehrenberg.
Mr. J. De Carle Sowerby.
Prof. Edward Forbes.
Prof. John Morris.

Prof. John Morris.

Mr. William Lonsdale.
Mr. Geddes Bain.

Mr. William Lonsdale.
M. Alcide d’Orbigny.

| Cape-of-Good-Hope Fossils.
(M. Alcide d’Orbigny.
Mr. William Lonsdale.
Prof. John Morris.

M. Joachim Barrande.
Prof. John Morris.

Prof. L. G. de Koninck.
Dr. 8S. P. Woodward.
Drs. G. and F. Sandberger.
Prof. G. P. Deshayes.
Dr. 8S. P. Woodward.
Prof. James Hall.

Mr. Charles Peach.

j Prof. T. Rupert Jones.
| Mr. W. K. Parker.
Prof. Auguste Daubrée.
Prof. Oswald Heer.
Prof. Ferdinand Senft.
Prof. G. P. Deshayes.
Mr. J. W. Salter.

Dr. Henry Woodward.
Mr. W. H. Baily.

M. J. Bosquet.

1873.
1874,
1875.
1876.
bisveg
1878.
1879.
1880.
1881.
1882.
1885.
1884.
1885.
1886.
1887.
1888.
1889.
1890.
1891.
1892.
18953.
1894.
1895.
1896.
1897.
1898.
1899.
1900.
1901.
1902.
1903.
1904.

Prof. John Wesley Judd.
Dr. Henri Nyst.

Prof. L. C. Miall.

Prof. Giuseppe Seguenza.
Mr. Robert Etheridge, Jun,
Prof. William Johnson Sollas.
Mr. Samuel Allport.

Mr. Thomas Davies.

Dr. Ramsay Heatley Traquair.
Dr. George Jennings Hinde.
Prof. John Milne.

Mr. Edwin Tulley Newton.
Dr. Charles Callaway.

Mr. J. Starkie Gardner.

Mr. Benjamin Neeve Peach.
Dr. John Horne.

Dr. Arthur Smith Woodward.
Mr. William A. E. Ussher.
Mr. Richard Lydekker.

Mr. Orville Adelbert Derby.
Mr. John George Goodchild.
Mr. Aubrey Strahan.

Prof. William W. Watts.
Mr. Alfred Harker.

Dr. Francis Arthur Bather.
Prot. Edmund J. Garwood.
Prof. John B. Harrison.

Mr. George Thurland Prior,
Mr. Arthur Walton Rowe.
Mr. Leonard James Spencer.
My. L. L. Belinfante.

Miss Ethel M. R. Wood.

Vol.

60. |

ANNUAL REPORT.

xxix

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.’

1875.
1874.
1875.
1876.
1877.
1878.
1879.
1880.
1881.
1882.
18853.
1884.
1885.
1886.
1887.

1885

1889.

Mr. William Davies.
Dr. J. J. Bigsby.

Mr. W. J. Henwood.

Mr. Alfred R. C. Selwyn.
The Rev. W. B. Clarke.

Sir Frederick M‘Coy.
Mr. Robert Etheridge.
Sir Archibald Geikie.
Prof. Jules Gosselet.
Prof. H. R. Goeppert.
Dr. Henry Woodward.

Mr. William Whitaker.
The Rev. Peter B. Brodie.
Prof. J. S. Newberry.
Prof, James Geikie.

Prof. Hanns Bruno Geinitz.

Dr. Ferdinand von Roemer.

1890.
1891.
1892.
1893.
1894.
1895.
1896.
1897.
1898.

1899.

1900.
1901.
1902.
1905.
— 1904.

Prof. Edward Hull.

Prof. Waldemar C. Brégger.

Prof. A. H. Green.

The Rev. Osmond Fisher.

Mr. William T. Aveline.

Prof. Gustaf Lindstroem.

Mr. T. Mellard Reade.

Mr. Horace B. Woodward.

Mr. Thomas F.. Jamieson.
Mr. Benjamin N, Peach.

ine John Horne.

Baron A. E. Nordenskiceld,

Mr. A. J. Jukes-Browne.
Mr. Frederic W. Harmer.
Dr. Charles Callaway.

Prof. George A. Lebour.

eK PROCEEDINGS OF THE GEOLOGICAL society. {May 1go4,

AWARDS
OF THE

BALANCE OF THE PROCEEDS OF THE
‘MURCHISON GEOLOGICAL FUND,’

1873. Prof. Oswald Heer. 1889. Prof. Grenville A. J. Cole.
1874. Mr. Alfred Bell. 1890. Mr. Edward B. Wethered.
1874, Prof. Ralph Tate. 189], The Rey. Richard Baron.

1875. Prof. H. Govier Seeley. | 1892. Mr. Beeby Thompson.
1876. Dr. James Croll. 1893. Mr. Griffith J. Williams.
1877. The Rev. John F. Blake. 1894. Mr. George Barrow.

1878. Prof. Charles Lapworth. 1895. Mr. Albert Charles Seward.
1879. Mr. James Walker Kirkby. | 1896. Mr. Philip Lake.

1880. Mr. Robert Etheridge. 1897. Mr. Sydney 8. Buckman.
1881. Mr. Frank Rutley. 1898. Miss Jane Donald.

1882. Prof. Thomas Rupert Jones. | 1899. Mr. James Bennie.

1883. Dr. John Young. | 1900. Mr. A. Vaughan Jennings.
1884. Mr. Martin Simpson. | 1901. Mr. Thomas S. Hall.

1885. Mr. Horace B. Woodward. | 1902. Mr. Thomas H. Holland.
1886. Mr. Clement Reid. 1903. Mrs. Elizabeth Gray.
1887. Mr. Robert Kidston. 1904, Dr. Arthur Hutchinson.

1888. Mr. Edward Wilson.

AWARD OF THE PROCEEDS
OF THE
‘DANIEL-PIDGEON FUND,

FOUNDED BY MRS. PIDGEON, IN ACCORDANCE WITH THE
WILL OF THE LATE

DANIEL PIDGEON, EGS.
‘The annual interest 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.’

1905. Dr. Ernest Willington Skeats.

Vol. 60. |

ANNUAL REPORT.

XXXl1

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 given annually’ (or from time to time) ‘as a mark of honorary
distinction and as an expression on the part of the governing body of the Society
that the Medallist (who may be of any country or either sex) has deserved well
of the Science, —‘ not less than one third of the annual interest [of the fund] to
accompany the Medal, the remaining interest to be given in one or more portions
at the discretion of the Council for the encouragement of Geology or of any of
the allied sciences by which they shall consider Geology to have been most
materially advanced, either for travelling expenses or for a memoir or paper
published, or in progress, and without reference to the sex or nationality of the
author, or the language in which any such memoir or paper may be written.’

1876.
1877.
1878.
1879.
1880.
1881.
1882.
1885.
1884.
1885.
1886.
1887.
1888.
1889.
1890.

Prof. John Morris.

Sir James Hector.

Mr. George Busk.

Prof. Edmond Hébert.
Sir John Evans.

Sir J. William Dawson.
Dr. J. Lycett.

Dr. W. B. Carpenter.

Dr. Joseph Leidy.

Prof. H. Govier Seeley.
Mr. William Pengelly.
Mr. Samuel Allport.
Prof. Henry A. Nicholson.
Prof. W. Boyd Dawkins.

Prof. Thomas Rupert Jones. |

| 1891.
1892.
1893.
1894,
1895.
1896.
1897.
1898.
1899.
1900.
1901.

1902.

1905.
1904.

Prof. T. McKenny Hughes.
Mr. George H. Morton.
Mr. Edwin Tulley Newton.
Prof. John Milne.
The Rev. John F. Blake.
Dr. Arthur Smith Woodward.
Dr. George Jennings Hinde.
Prof. Wilhelm Waagen.
Lt.-Gen. C. A. McMahon.
Dr. John Edward Marr.
Dr. Ramsay Heatley Traquair.
ae Anton Fritsch.

Mr. Richard Lydekker,
Mr. Frederick William Rudler.
Prof, Alfred G. Nathorst.

EX KE PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

AWARDS

OF THE

BALANCE OF THE PROCEEDS OF THE
‘LYELL GEOLOGICAL FUND,’

1876. Prof. John Morris. | 1892. Mr. Edwin A. Walford.
1877. Mr. William Pengelly. | 1893. Miss Catherine A. Raisin.
1878. Prof. Wilhelm Waagen. | 1893. Mr. Alfred N. Leeds.

1879. Prof. Henry A. Nicholson. | 1894. Mr. William Hill.

1879. Dr. Henry Woodward. | 1895. Mr. Perey Fry Kendall.
1880. Prof. F. A. von Quenstedt. | 1895. Mr. Benjamin Harrison.
1881. Prof. Anton Fritsch. | 1896. Dr. William F. Hume.
1881. Mr. G. R. Vine. | 1896. Dr. Charles W. Andrews.

1882. The Rey. Norman Glass. | 1897. Mr. W. J. Lewis Abbott.
1882. Prof. Charles Lapworth. 1897. Mr. Joseph Lomas.

1883. Mr. P. H. Carpenter. | 1898. Mr. William H. Shrubsole.
1883. M. Ed. Rigaux. 1898. Mr. Henry Woods.

1884. Prof. Charles Lapworth. 1899. Mr. Frederick Chapman.
1885. Mr. Alfred J. Jukes-Browne. 1899. Mr. John Ward.

1886, Mr. David Mackintosh. 1900. Miss Gertrude L. Elles.
1887. The Rev. Osmond Fisher. 1901. Dr. John William Evans.
1888. Dr. Arthur H. Foord. | 1901. Mr. Alexander McHenry.
1888. Mr. Thomas Roberts. | 1902. Dr. Wheelton Hind.

1889. M. Louis Dollo. | 1903. Mr. Sydney S. Buckman.
1890, Mr.Charles Davies Sherborn, | 1903. Mr. George Edward Dibley.
1891. Dr. C. I. Forsyth Major. _ 1904. Dr. Charles Alfred Matley.

1891. Mr. George W. Lamplugh. | 1904. Prof.Sidney Hugh Reynolds.
1892. Prof. J. Walter Gregory. |

AWARD OF THE PRESTWICH MEDAL,

ESTABLISHED UNDER THE WILL OF THE LATE

SIR JOSEPH PRESTWICH, F.RS., F.G.S.

To apply the accumulated annual proceeds... at the end of every three (or every
six) years in providing a Gold Medal...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.’

1903, John Lubbock, Baron Avebury.

Vol. 60. ] ANNUAL REPORT. XXXill

AWARDS OF THE BIGSBY MEDAL,
FOUNDED BY THE LATE
Dr. J. J. BIGSBY, F.RS., F.GS.

To be awarded biennially ‘as an acknowledgement of eminent services in any depart-
ment of Geology, irrespective of the receiver’s country; but he must not be
older than 45 years at his last birthday, thus probably not too old for further
work, and not too young to have done much.’ :

1877. Prof. Othniel Charles Marsh. 1891. Dr. George M. Dawson.
1879. Prof. Edward Drinker Cope. 1893. Prof. William Johnson Sollas.

1881. Prof. Charles Barrois. 1895. Mr. Charles D. Walcott.
1883. Dr. Henry Hicks. 1897. Mr. Clement Reid.

1885. Prof. Alphonse Renard. 1899. Prof. T. W. E. David.
1887. Prof. Charles Lapworth. 1901. Mr. George W. Lamplugh.
1889. Mr. J. J. Harris Teall. 1905. Dr. Henry M. Ami.

AWARDS OF THE PROCEEDS OF THE BARLOW.
JAMESON FUND,
ESTABLISHED UNDER THE WILL OF THE LATE

Dr. H. C. BARLOW, E.G:S.

The perpetual interest to be applied every two or three vears, as may be approved hy
the Council, to or for the advancement of Geological Science.’

1879, Purchase of Microscope. 1893. Purchase of Scientific In-
1881. Purchase of Microscope- | struments for Capt. F. E.
Lamps. | Younghusband.

1882, Baron C. yon Ettingshausen. | 1894. Dr. Charles Davison.
£362) Pe. James Croll. + 1896. Mr. Joseph Wright.

1896. Mr. John Storrie.
1898. Mr. Edward Greenly.
1900. Mr. George C. Crick.

1884. Prof. Leo Lesquereux.
1886. Dr. H. J. Johnston-Lavis.

1888. Museum. 1900. Prof. Theodore T. Groom.
1890. Mr. W. Jerome Harrison. | 1902. My. William M. Hutching

1892. Prof. Charles Mayer-Eymar, | 1904, Mr, Hugh J. LL), Beadnell,

XXXIV PROCEEDINGS OF THE GEOLOGICAL SoclETY. [May 1go4,

INCOME EXPECTED.

Estimates for

S a & 2 Oye.
GWOMPOSIMONS 55.5 < 0 ost BE fines oss on Sele ete et ee 134 0 0
Due for Arrears of Admission-Fees .......... 15 12;0
mamission-Wees, L004 oi. sss 5 buen apes ae 200 0 O
= ‘B7a 127.8
Arrears of Annual Contributions ............ 150 0 0
Annual Contributions, 1904, from Resident and
Non-Resident Fellows 2. <..5: see eee ss L770 O20
Annual Contributions in advance ............ DD) 0". 0
— 1970 0 0
Sale of Quarterly Journal, including Longmans’
MCCOUNE (5.04 soe ays ee glee eee ere ota eee 150 0 0
Sale of Transactions, General Index, Library-
Catalogue, Museum -Catalogue, Hutton’s
‘Theory of the Tarth’ vol. ii, Hochstetter’s
‘New Zealand, and List of Fellows’ ;..y7.%..° “a... 510 0
Dividends on £2500 India 3 per cent. Stock .. 75 O O
Dividends on £300 London, Brighton, & South
Coast Railway 5 per cent. Consolidated Pre- — -
ference-Stock«\ '.)..%. Ms ase ee ee ee 15 1050
Dividends on £2250 London & North-Western
Railway 4 per cent. Preference-Stock ...... 90 0 0
Dividends on £2800 London & South-Western
Railway 4 per cent. Preference-Stock ...... 12: O°
Dividends on £2072 Midland Railway 23 per
cent. Perpetual Preference-Stock .......... 51 16 0
Dividends on £267 6s. 7d. Natal 3 percent. Stock. 8 O O
———— 35116 0
Neturned Income-Tax, from April 1901 to April
BOO eas: cic be. ja teieeauee s HERS he ois Gr kites wane: 41 0 0

£2927 18 0

Vol. 60. ] FINANCIAL REPORT.

the Year 1904.

EXPENDITURE ESTIMATED.

House-Expenditure :
BEE i. 10 x penne yaad Soc eT ea stb a

“Eo SUA fa Ole, “CR A eg eric SNE IE) es Oe ge

Pinibire and Eepaite.... ..:..02.-0seseserseacesoe
House-Repairs and Maintenance ...............
MRM SHOEI oe dss ce ne nce ch son mene
PR i CNMI Coco. oa ie vhs cs ceca nednceeensnnte
Washing and Sundry Expenses ..................

Salaries and Wages, etc. :

PEM SUATED SGCECIGEY 0. 20-5<0..--scen0-ces-ssscencens

Rf half Premium Life-Assurance...
Nae peIM RR DESTURNY 2505 coc ebe ns Selassie sss ccceenne
ee Bs CTR yi 5 eel win ton ay sre shen de<es cdabed
po rerenen ARI UIIG, Coa rdyck carat oak pach canes nae
House Porter and Upper Housemaid .........
Rr: EA ETINIEE 5 Soo enn ack dance xnasnuseosas

Office-Expenditure :
Pee MUNIE NN aris. elk Ua ad ev emma Ste Rees iva devics
Miscellaneous Printing, etc. .............00eceeee
Postages and Sundry Expenses ..................

International Catalogue of Scientific Literature
Library (Books and Binding)
New Fittings for Map-Room
Museum

Publications:

Quarterly Journal, including Commission on

BME sien: tdi nuae what e Se. MORE eh W/O ds ech
Record of Geological Literature
TA ODM 6.2 ci ances a SRG RLS es ai a Suse
Postage on Journal, Addressing, ete.
Abstracts, including Postage ...........0.......4.
Dibrary-Capateeue. - 5501 sb..csldietscdecsevnd conse

ee

£

Skee Oe ee eee ee) ee Oe ee eee ee ea ee) Ge ae ee he ee) ee ee

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—

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XXXV

Ce
a2 Th 0
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1550. 0
a | a
200 O O
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Pale URE
1368 10 O

£2927 18 0

W. T. BLANFORD, Treasurer.

January 28th, 1904. -

XXXV1

PROCEEDINGS OF THE GEOLOGICAL SOCIETY.

[May 1904,

Income and Expenditure during the

RECEIPTS.

To Balance in the hands of the Bankers at

Januany 186, 1903). 2. ee gine

,» Balance in the hands of the Clerk
January Ist, 1903

oe Jee. 0:0 [0 Soin ef ee Le

,, Compositions

,, Admission-Fees :
Arrears
Current

ay

a

» Arrears of Annual Contributions
» Annual Contributions, 1903 ........
., Annual Contributions in advance

,, Publications :
Sale of Quarterly Journal *:

. Molssr to-lviti*",.. 22e-: ce eee
a Wiel, lite ieee Se Gere ae eh eee
jo PE PaMeactioney 9. .c. cen s-.- eee ee
» Ormerodis: Index 4.45.5.<) o ee
yy ‘General Index ws. .s..s5-cennce ee
,, Record of Geological Literature .

> astot Mellowsare-e.o.csacce ee
», Museum-Catalogue - ................:.
» doibrary-Catalogiie 4 nncn5.00cgee ence
» Hochstetter’s ‘New Zealand’ ......
» Hutton’s ‘Theory of the Earth’

vol. iii

eet sees were ee sere rsr ser ssreserer

,», Dividends (less Income-Tax) :—
£2500 India 3 per cent. Stock....

£300 London, Brighton, & South
Coast Railway 9 per cent.

Consolidated
Stock

C50 Selle Jere) se (6 (6 6) elie, es nae.

Preference-

£2250 London & North-Western
Railway 4 per cent. Pre-

ference-Stock

£2800 London & South-Western
Railway 4 per cent. Pre-

ference-Stock

wera) ae) eas) (a io

£2072 Midland Railway 24 per
cent. Perpetual Preference-

Stock

© Oe © 0 © © © = 6 @ «| © .2@e oe

£267 6s. 7d. Natal 3 per cent. Stock

* Due from Messrs. Longmans & Co., in addition

to the above, on Journal, Vol. lix, ete....... £65

Sow RE te Sepa ee
56 stoma
AA 2O
we GLis- 7 tS
as Wie SNe Lat ee AD
94 10 O
201 12: 70
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$22 BR EO
£3003 0, %9
32206 Ain 5D ae eee

Vol. 60. ]

FINANCIAL REPORT,

Year ended December 31st, 1903.

By House-Expenditure:

Taxes

ee

Fire-Insurance

PAYMENTS.

ee

eee eee eee eee eee eee ee eee eee es

Electric Lighting and Maintenance .........
SR Oe SR eve ee Ped 208 OF ok RE

Furniture and Repairs

House-Repairs and Maintenance...............

Annual Cleaning
Tea at Meetings

eee eee eee eee eee eee eee eee eee

Washing and Sundry Expenses ...............

», Salaries and Wages:
Assistant Secretary

93

half Premium Life-Assurance...
Assistant Librarian
Assistant Clerk
Junior Assistant

eee eee eee eee ee ee

Oe ee ee ee

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House Porter and Upper Housemaid _......

Under Housemaid

,, Office-Expenditure :

Stationery

a

Se ay

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Miscellaneous Printing, ete.

ee ee ee ee

Postages and Sundry Expenses ...............

SS 8. ae
£3. <0

lb 08 0
4617 8
14 310
58 12 9
ao 2
2 0 6
9 9 6
19 16 -5
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390 O O
10 lj 0
150 0 O
14s. 0
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87 19 O
48 19 6
814 0O
10 10 OU
2D a, O
45 14 11
46733

,, International Catalogue of Scientific Literature

,, Library (Books and Binding)

», Prestwich Fund; Advance for Dies and Legal

Expenses
,, Publications:

Commission on Sale of Quarterly Journal .
Paper, Printing, and Illustrations .........

Postage and Addressing

Stitching and Covering back Numbers
Record of Geological Literature ............

List of Fellows
Abstracts, including Postage
Library-Catalogue
Museum-Catalogue

ed

ee a

,, Balance in the hands of the Bankers at

December 31st, 1903

,, Balance in the hands of the Clerk ....

We have compared this Statement with
the Books and Accounts presented to us,

and find them to agree.

Kr. Ww RUDLER, | Auditors. S000 a, ©
G. T.. PRIOR, \ aay :

W. T. BLANFORD, Treasurer.
January 28th, 1904.

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Vol. 60. | ANNIVERSARY MEETING—WOLLASTON MEDAL, xli

AWARD oF THE Wotiaston MEDAL.

In handing the Wollaston Medal, awarded to Prof. Atserr Her,
of Ziirich, to Mr. J. J. H. Tears, M.A., F.R.S., for transmission to
the recipient, the CuarrMan addressed him as follows :—

Mr, Tratt,—

The Council of the Geological Society of London have awarded
to Prof. Heim the highest honour which they have to bestow—
the Wollaston Medal, in recognition of the value of his researches
concerning the mineral structure of the Earth, and more especially
of his contributions towards the elucidation of the structure of
mountain-masses, as illustrated in the chain of the Alps. In
his great monograph, the ‘ Mechanismus der Gebirgsbildung, he
traced with remarkable skill the influence of plication in the
terrestrial crust, following this influence step by step from the
distortion and fracture of organic remains in hand-specimens up
to the most gigantic foldings which have comprised a vast mountain-
chain in their embrace. His researches, however, have not been
confined to the internal structure of the Alps. He has devoted
himself with not less enthusiasm and success to the study of their
glaciers and their landslips. Gifted with no ordinary artistic power,
he has been able to enrich geological science with a valuable series
of landscape-drawings and sections, in which the intimate relations
of geology and topography are admirably delineated. His latest
achievement in this department is a large model of the massif of
the Hohe Santis, which was exhibited at the recent meeting of the
International Geological Congress in Vienna. It was admitted by the
assembled geologists to be probably the most accurate and beautiful
model of a mountain-group that had ever been constructed. We
may judge of the labour and enthusiasm spent on it from the
fact that, besides climbing to every crest of that rugged tract,
Prof. Heim made many ascents in a balloon, so as to obtain
detailed and comprehensive bird’s-eye views of the whole region
which he wished to depict. In asking you to be so good as to
transmit to him this Medal, I would request you to convey with
it an expression of our warmest wishes for a long continuance
of the mental and bodily activity which he has so unsparingly
devoted to the interests of our science.

VOL. LX. d

xhi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. {| May 1904,

Mr. Tratt, in reply, read the following translation of a letter
which had been forwarded by the recipient :—

‘I much regret that my duties here make it impossible for me to be presént at
your Annual Meeting, and that I am therefore unable in person to express my thanks
for the honour which you are conferring upon me.

“It may perhaps interest you to know the circumstances which led me to turn
my attention to Geology. When, at the age of nine years, I visited the Alps for the
first time, in company with my father, the mountains appealed to my youthful
imagination, and I then conceived the idea of representing them not only on paper
but also in relief. I accordingly attempted to model them in clay, working at first
directly from nature, and afterwards by the aid of the topographic maps which were
then appearing. I soon found that one can only represent correctly that which one
understands, and I was thus led to study the internal structure as well as the
external form of the mountains.

‘At the age of sixteen years I had prepared a model of the Tédi group on a scale
ot 1: 25,000. Arnold Escher von der Linth heard of this model, and came to see
it at my own home. This was the first time that I saw that illustrious man. He
invited me to accompany him on a geological excursion, and from that time onward
I looked up to himas my revered master. Thus the pleasure which I derived from my
early visits to the mountains and my desire to represent them in relief led me naturally
to the study of Geology.

‘In receiving this high honour at your hands, I remember with heartfelt gratitude
the instruction and encouragement that I lave derived from a study of the
literature and geology, and especially from personal intercourse with the fellow-
workers, of the great nations which le beyond my own small fatherland. Among
these I reckon the British Empire as especially deserving of my gratitude. More
than 35 years ago I derived inspiration as a student from a study of the works of
Sir Charles Lyell, and since that time have continued to hold intercourse with
British geologists—many of them Fellows of your Society—and to study their
writings and collections.

‘I am conscious that my work is very imperfect, and that in it error is mixed
with truth. My life is unfortunately so overburdened with official and private
duties that I have but little time for original research ; yet I am filled with an
earnest desire to do more, for I recognize that in such research is to be found the
greatest happiness that human life can afford.

‘It seems to me that the work which I have accomplished does not entitle me to
this honour. I prefer rather to regard it as the recognition of a sincere effort to
extend our knowledge, and I can assure you that, so far as in me lies, the remainder
of my life shall be devoted to this object. You have given me a fresh stimulus—

new encouragement. I thank you from the bottom of my heart.’

AWARD oF THE Murcuison MEDAL.

The Curran then presented the Murchison Medal to Prof. Guorex
ALEXANDER Louis Lepour, M.A., M.Sc., addressing him in the
following words :—

Prof. Lenour,—

The Council have this year awarded to you the Murchison Medal,

Vol. 60.] | ANNIVERSARY MEETING—MURCHISON MEDAL. xii

in recognition of the importance of your contributions to our know-
ledge of the Carboniferous and other rocks of the North of England.
For thirty years you have been engaged in these researches, which
have resulted in more accurate determinations of the stratigraphy
of the Carboniferous System of Northumberland, and more satisfac-
tory correlations of the various divisions of that system throughout
the northern counties. In conjunction with Mr. Topley you
brought forward convincing evidence that the famous Whin Sill
is an intrusive sheet, and not, as some observers had supposed, an
intercalated lava. Your papers on the salt-measures and on the
Marl-Slate and Yellow Sands of your district have likewise added to
our knowledge of these formations. This original work, however, has
for many years been carried on in the intervals of a life primarily
devoted to the teaching of geology, and we wish to mark our sense
of the value of your educational labours as a Professor in the
University of Durham. As one who in former days served under
Murchison, you will doubtless value this medal as another link con-
necting you with that great master of our science. J] may perhaps
be permitted to add an expression of my own gratification that,
looking back on my early association with you as a colleague in the
Geological Survey, it has fallen to me to hand you to-day this mark
of appreciation from the Council of the Geological Society.

Prof. Lesour replied as follows :—
Sir ARCHIBALD GEIKIE,—

My feelings on this occasion are divided between regret at the
absence of my old triend, Prof. Lapworth, and gratification at
receiving the Medal which commemorates my first Chief, Sir
Roderick Murchison, from the hand of one who was his favourite
colleague, his successor, and his biographer. An Award such
as this is of the greatest value to a teacher: it confirms his
pupils in the trust which they place in him, and at the same
time gives him confidence in carrying on his own work. In my
case, I will not be so presumptuous as to question the propriety of
the Council’s decision, however it may have surprised me. I am
especially pleased that in the too kind words that you have uttered,
the name of my dear friend and colleague of long ago, William
Topley, has once more been coupled with mine. I am sure that no
one would have rejoiced more than he at my gocd fortune this day.

d 2

xliv PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

I beg most heartily to thank the Council for the honour which they
have done me.

AWARD OF THE LYELL MEDAL.

In handing the Lyell Medal, awarded to Prof. Atrrep GaBRieL
Naruorsr, of Stockholm, to Baron C. de Bripr, Envoy Extraordinary
and Minister Plenipotentiary of H.M. the King of Sweden &
Norway, for transmission to the recipient, the CHarrman addressed
him as follows :—

Baron DE Bripr,—8

Your Excellency has been good enough to come here to-day to
receive for your countryman, Prof. Nathorst, of Stockholm, the
Lyell Medal, which has been awarded to him this year by the
Geological Society in recognition of his long and distinguished
labours to advance our knowledge of the vegetation which at
successive periods in the history of the earth has flourished in
Northern Europe and the Arctic regions, These labours range
from the oldest to the youngest ages of geological time. Among
the most ancient rocks various curious markings, which had gene-
rally been regarded as traces of marine plants, were shown many
years ago by Prof. Nathorst, after an ingenious series of experi-
ments, to be probably not of vegetable origin. But while he thus
cut off what had been supposed to be an early marine flora, he has
greatly extended our acquaintance with the terrestrial floras of
Paleozoic time in the Arctic regions. - His papers on the extension
of the vegetation of the Upper Old Red Sandstone as far north as
Bear Island, continuing the earlier work of Heer, are of special
interest. He has thrown much light on the flora of the Triassic
deposits that extend into the South of Sweden. From the far
northern King Charles Land he has made known the existence of a
Jurassic and a Cretaceous flora, His researches among Pleistocene
and recent deposits, and the history which he has thence deduced
of plant-migration and changes of climate in Europe, are singularly
interesting andsuggestive. Although it is as a student of fossil plants
that Prof. Nathorst is most widely known, it was his keen eyes that
detected for the first time casts of medusze in the Lower Cambrian
rocks of Scandinavia. In transmitting to him our Lyell Medal,
your Excellency will, | hope, accompany it with an expression

Vol. 60. |} ANNIVERSARY MEETING—WOLLASTON FUND. xlv

of our best wishes for his health and the long continuance of his
scientific energy.

Baron de Birpr, in reply, read the following letter which he had
received from Prof. Narnorst :—

“Allow me to express my heartiest thanks to the Council for the great and quite
unexpected honour which they have conferred upon me by the award of the Lyell
Medal. I regard this mark of approval of my geological and palxontological labours
as a most gratifying distinction, and it encourages me to hope that, as the end of my
life approaches, I may have the satisfaction of feeling that I have not lived altogether
in vain.

“My gratification at receiving this honour is increased by the fact that it is
associated with the name of Sir Charles Lyell. I vividly remember the enthusiasm
with which, as a mere youth, I réad the Swedish edition of his admirable and
fascinating ‘ Principles of Geology’ ; and it is only right to add that it was this work
which first excited my love for Geology; a branch of science which the Geological
Society of London has vigorously promoted for almost a century.

‘During my first visit to England in 1872, at the age of twenty-one, I was fortunate
enough to be introduced to the great British geologist; and I still cherish a vivid
remembrance of his kind and noble personality, and of his keen interest in my then
recent discovery of the remains of Salix polaris and other Arctic plants in the
Glacial deposits of the Norfolk coast. ‘The meeting with Sir Charles forms one
of the most highly-prized reminiscences of my youth.

‘Let me also express my great satisfaction at receiving this Medal through so
illustrious a geologist as Sir Archibald Geikie, whose writings have served as a
source of information to the majority of geologists throughout the world.’

AWARD OF THE WoLtAston Donarton-F UND.

The Cuarrman then handed the Balance of the Proceeds of the
Wollaston Donation Fund, awarded to Miss Erorn Mary REeapER
Woop, M.Sc., to Dr. J. E. Marr, F.R.S., for transmission to the
recipient, and addressed him in the following words :—

Dr. Marr,

The Council have awarded to Miss Wood the Balance of the
Proceeds of the Wollaston Donation-Fund as an acknowledgment of
the value of her contributions to our knowledge of the Graptolites and
of the rocks in which these organisms occur. Her papers furnish an
excellent example of the application of zonal stratigraphy to groups
of rocks which were thought to be already known with tolerable
completeness. Much still remains to be done in this department
of investigation. We had looked forward with pleasure to seeing

xlvi PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

her among us here to-day; but she has been unavoidably pre-
vented from coming to London. In sending the Award to her,
you will be so good as to express to her our hope that she will
regard it as a token of the interest which we take in her work, and
as an encouragement to her to continue to devote herself to the
cause of science with the same skill and enthusiasm which have
hitherto so eminently distinguished her career.

AWARD OF THE Murcuison GrotoaicaL Funp.

In presenting the Balance of the Proceeds of the Murchison
Geological Fund to Dr. Artaur Hutcurson, M.A., F.C.S., the
CuarrMaAN addressed him as follows :—

Dr. Hvrcurnson,—

The Balance of the Proceeds of the Murchison Geological Fund
has this year been awarded to you, in acknowledgment of the
ability which the Council recognize in your published memoirs on
mineralogical subjects, and to encourage you in further work. We
especially desire to acknowledge the skill and industry displayed by
you in two important memoirs. Your paper on the Diathermancy
of Antimonite introduced and successfully applied a new method of
crystallographic investigation, wherein an opaque mineral is
examined between crossed nicols, by means of transmitted heat-
rays, corresponding to the usual optical examination of transparent
minerals. Your memoir on Stokesite records the discovery of a
new mineral, of which you found only a single crystal upon
a specimen of Cornish axinite. Your analysis proved it to be a
compound of most unusual type—a silicate containing tin.

AWARDS FROM THE LYELL GroLogicaL Funp.

The Cuarrman then presented a moiety of the Balance of the
Proceeds of the Lyell Geological Fund to Prof. Stpney Hueu
Reynoups, M.A., addressing him in the following words :—

Prof. ReyNoLps,—

This Award is made to you in special recognition of the value of

Vol. 60. | ANNIVERSARY MEETING—LYELL FUND. xlvii

your contributions to our knowledge of the Paleozoic rocks
of Ireland and of the geology of the Bristol district, and to
encourage you in further work. During the past eight years the
Society has received from you a series of important papers which
have appeared in its Quarterly Journal. In association with
Mr. Lake you presented some interesting facts in regard to the
Lingula-Flags of the Dolgelly district. In conjunction with
Mr. Gardiner you have carried out a series of researches among the
Silurian rocks of the South-East and of the West of Ireland, and
have thrown fresh light on their associated volcanic rocks. Together
with Prof. Lloyd Morgan, you have worked out the geology of the
Tortworth district, and have cleared up the interesting history of
its volcanic eruptions; while you have more recently studied the
Carboniferous volcanic rocks of the neighbourhood of Weston-super-
Mare. In addition to all these geological undertakings you are
still further widening the range of your studies by continuing the
Paleontographical Society’s Memoir on the Pleistocene Mammalia.
We cordially hope that many long years of active scientific work
are in store for you, and that you will continue to enrich our
Quarterly Journal with the results of your researches.

In handing the other moiety of the Balance of the Proceeds of the
Lyell Geological Fund, awarded to Dr. Cuartes Atrrep Marttey, to
Prof. W. W. Warts, M.A., M.Sc., Sec.G.S., for transmission to the
recipient, the Cuarrman addressed him as follows :—

Prof. Warts,—

The other moiety of the Lyell Fund has by the Council been assigned
to Dr. Matley, as an acknowledgment of the value of his work in
elucidating the geology of Anglesey, and to encourage him in
further work. The complicated structure of that part of North
Wales has long been recognized, but the nature and extent of the
complication have only been realized in recent years, since more
enlarged and accurate views of geological tectonics have been
reached. It would be rash to assert that all the difficulties have
been cleared away, but Dr. Matley has made a notable forward step
in removing them. Besides his work in Anglesey he has devoted

xlviil PROCEEDINGS OF THE GEOLOGICAL sociETy. {May 1904,

time and thought to the Cambrian formations of Pembrokeshire,
and to the Keuper Marls and Sandstones of Warwickshire. We
wish him many years of health and continued geological industry.

AWARD OF THE BARLOW-J AMESON FUND.

The CuarrMan then handed the Proceeds of the Barlow-Jameson
Fund, awarded to Mr. Hueu Jonn Liewettyn Brapnert, to Major
C. E. Brapnetr, late R.A., for transmission to the recipient,
addressing him in the following words :—

Major BrapneLLt,—

The Barlow-Jameson Fund is awarded to your son, Mr. Hugh John
Llewellyn Beadnell, in recognition of the value of his Memoirs on
the topography of the Oases and other districts of the Libyan
Desert, and for his important collections of vertebrate fossils made
in Egypt during the last three years. The enthusiasm with which
he has prosecuted his researches in the Geological Survey of Egypt
led some time ago to an attack of fever which nearly proved fatal.
We hope that he will be able henceforth to ward off all such
attacks, and to continue the career which he has so successfully
begun. In transmitting to him this Award of the Council, you
will not fail to convey to him an expression of our interest in his
researches, and of our hope that he will be encouraged to continue
to pursue them.

Vol. 60.] ANNIVERSARY ADDRESS. xlix

THE ANNIVERSARY ADDRESS DELIVERED BY

Sir ArcHIBALD Gerxkiz, Sc.D., D.C.L., LL.D., Sec.R.S.,
Vicr-PRESIDENT.

I propose, first of all, to refer to the most conspicuous losses which
our ranks have sustained during the past year.

J. P. Lestey, one of the most distinguished and loveable men
of science in the United States, was born at Philadelphia on
September 17th, 1819. His grandfather was a cabinet-maker in
Aberdeenshire, whence he had emigrated to America, carrying with
him and transmitting to his descendants his Scottish strength of
character, energy, industry, and uprightness. His father, who
followed the same trade, taught his children to draw even before
they learnt to write, and trained their observing faculties by re-
quiring from them accurate descriptions of what they had seen or
heard, illustrated with sketches which he criticized. In this way,
and by practice in his father’s workshop, Lesley acquired that
accuracy of eye and deftness of hand which afterwards became
such notable gifts in his qualifications as a geologist. He was
christened Peter after his father and grandfather, and at first
wrote his name ‘ Peter Lesley Jr.,’ but disliking the Christian
appellation that had been given to him, he eventually transformed
his signature by putting the J of ‘Junior’ at the beginning, followed
by only the first letter of ‘Peter.’ Hence arose the familiar signature
of ‘J. P. Lesley.’

His parents, recognizing the promise of his boyhood and youth,
educated him for the ministry, and he took the degree of A.B. at
the University of Pennsylvania in 1838. But his application to
his studies, combined with his neglect of bodily exercise and training,
so told upon his health that he was unable to go on immediately with
the theological training which had been planned. Fortunately for
him, and not less so for the science of geology in the United States,
it happened that the infant Geological Survey of Pennsylvania was
then attracting attention, under its able chief H. D. Rogers, and
the place of sub-assistant on the staff was offered to young Lesley.
Accepting this appointment, he began his geological career at the
age of nineteen in the Pottsville anthracite-field, under Whelpley,
who was in later years described by Lesley himself as ‘the first

J PROCEEDINGS OF THE GEOLOGICAL sociEry. [May 1904,

perfect topographical geologist our science had.’ Those who have
travelled through the Carboniferous region of Pennsylvania, or
have studied the excellent detailed maps of it which the State
Surveys have published, will not wonder at the claim made by
Lesley that ‘ topographical geology was born’ in that State; nor
will they fail to note how easily and irresistibly Lesley was led
into that domain of geology where he became so pre-eminent a
master. The contours of the surface depend so directly and clearly
upon curvature and fracture of the terrestrial crust on the one hand,
and upon the results of erosion on the other, that in few tracts of
the earth’s surface is this relationship so readily grasped, or appeals
so powerfully to the imagination.

Before he was one-and-twenty Lesley had constructed his first
topographical and geological sketch-map, which earned the com-
mendation of Rogers ‘for the faithful and laborious manner in
which he had unfolded the geology of this occasionally complicated
zone of country.’ His scientific career, however, was soon arrested
by the refusal of the State Legislature to grant any further appro-
priation for the continuance of the Survey, and by the consequent
disbanding of the staff of assistants. Thus thrown back upon himself,
the young geologist turned once more to the line of life which had
been originally marked out for him. His geological rambles among
the remote valleys of his native State had brought vividly before his
eyes the benighted condition of their inhabitants ; and now the idea
was revived that he should proceed with his theological studies, in
order to fit himself for the ministry and for eventually becoming a
missionary to these neglected people. He accordingly entered the
Theological Seminary at Princeton in 1841, and likewise proceeded
to his degree of A.M. at the University of Pennsylvania. While
working at Hebrew and theology, however, he found time, at
Rogers’s request, and with much patience and skill, to put together
the mass of materials that had been gathered by the assistants for
the construction of a coloured topographical and geological map ot
Pennsylvania. In this laborious task, as in all his subsequent
labours, the value of his early training in drawing became strikingly
conspicuous.

Having passed through the theological training, and having
received his licence as a clergyman from the Presbytery of Phila-
delphia, he took a trip to Europe in 1844. Landing in Liverpool,
he first made a walking pilgrimage through England, and thereafter
another, with knapsack on back, through the west and south of

Vol. 60. ] ANNIVERSARY ADDRESS, li

France and the west and north of Switzerland. His eyes being
now opened to the perception of geological structure, he made good
use of his opportunities in Dauphiné and in the Jura, where he
could compare the plicated rocks of these classic regions with those
which he had learnt to understand at home. He found in the
Swiss ground proofs of ‘ the ancient action of similar forces under
the same laws, but in less detail and with far less delicacy. He
remarks that he ‘ was fortunate in being the first geologist who
had an opportunity to approach the dynamic phenomena of the
Jura with an American eye, trained on the typical [Appalachian |
ground.’ Making his way through the Harz he came to Halle, for
the purpose of remaining some months at its University, studying
under the theologian Tholuck and others, where he found the
theological atmosphere less close than that of his own home. He
returned to Philadelphia in the early summer of 1845, and at once
threw himself into the missionary work for which he had prepared.
He distributed Presbyterian tracts for the American Tract Society
of Philadelphia, through the northern and central parts of Penn-
sylvania, frequently preaching, and sometimes riding +0 miles in
aday. He continued these labours for two seasons, until at last
his health failed under the combined strain of mental excitement,
bodily fatigue, and exposure to the weather.

At the end of the following year (1846) Rogers, who had never
lost sight of him or of the possibility of winning him back to the
geological camp, induced him to come to Boston and spend five
months there in duplicating the State geological map and longi-
tudinal sections which he had drawn while at Princeton, together
with some hundreds of other drawings, besides preparing a large
part of the text of the final Report. But the Legislature refused
to grant money for their publication. Lesley, however, still clung
to his ministerial calling, and towards the end of the year 1848
became the pastor of a Congregationalist church at Milton, a suburb
of Boston. arly next spring he married Miss Lyman—an union
which proved of the happiest kind, although it started with such
prospects of feeble health and straightened means that one of
their candid lady-friends remarked that ‘it was enough for the
pair to have the shelter of an umbrella, and if there should be
children parasols might be given them.’ Mrs. Lesley was his
genial sympathetic companion and helper through the rest of
his long life, the witness of and sharer in his successes, and
now in her widowhood the recipient of many expressions

In PROCEEDINGS OF THE GEOLOGICAL sociETY. — | May 1904,

of the esteem and affection with which her husband was
regarded.

Lesley’s theological views were slowly widening—a change which
roused the anxiety of the rigidly-orthodox institutions with which
he was connected. The Tract Society in Philadelphia began to
move in the interests of the people of Boston, and ultimately his
licence to preach was withdrawn. A portion of his congregation,
however, adhered to him, and to them he continued to minister.
But as he gradually became more completely Unitarian, he finally
abandoned his pastorate in 1851. He was now thirty-two years
of age—a time of life at which most men find it too late entirely to
change their vocation. He, however, had never quite abandoned
geological work, and he could revert to it with all the more eager-
ness, as, while it offered him the prospect of better health and
sufficient maintenance, it opened out to him a career fer which he
felt himself to be well qualified, in which he had already made his
mark, which promised him the most congenial occupation, and out
of which no theological wolves could scare him. The Pennsylvanian
Legislature in April 1851 at last made an appropriation for the
renewal of the Geological Survey, and Rogers immediately secured
Lesley as one of his chief assistants, his main object being to get
the maps reduced and published, together with the Report. Owing
to various causes, the publication was delayed for some years. but
meanwhile Lesley’s topographic power became generally known,
and brought him private employment. In 1853 and 1854 he was
engaged by the Pennsylvania Railroad Company to construct a
large map, which was distinguished by the adoption of contour-lines
instead of hachures. He undertook other surveys or geological
reconnaissances, not only in Pennsylvania, but in South-Western
Virginia and South-Eastern Tennessee.

In the midst of these avocations he found time, in the winter of
1855-56, to write his memorable little volume entitled ‘ Manual of
Coal & its Topography, illustrated by original drawings, chiefly
of facts in the Geology of the Appalachian region of the United
States of North America, by J. P. Lesley, Topographical Geologist.’
1 well remember the pleasure with which, many long years ago, I
first perused this original and suggestive treatise. It could only have
been written by a man who, gifted with a keen eye and artistic
power, had been enabled to cultivate his observing faculties in a
region where the fundamental facts of geological structure were
displayed with altogether exceptional clearness. It dealt with

Vol. 60. | ANNIVERSARY ADDRESS. hii

topography as no one had attempted to deal with it before. treating
it both as a science that classified the various features of the land
which are determined by geological structure, and likewise as an art
deserving of the most scrupulous care in its cultivation on the part of
the cartographer. ‘The face of the earth,’ he significantly wrote,
‘is the face of a great angel, with infinite smiles and anguish-lines.,
and profound sympathies with peace and suffering stamped upon its
features. Every lineament is a line of tragical history, full of
pathos and sublimity.’ If such was his conception of landscape, we
can readily understand with how deep an artistic feeling he must
have undertaken his work. ‘The topographer,’ he tells us, ‘if a
true artist, will put himself in true relations with this grand mute
object ot his study, and learn its own record of its wonderful ex-
perience, if he will picture the earth as it is. The draughtsman
must first be a geologist.’ Only a small edition of this remarkable
book was published, and it was never reprinted. Hence it has
been much less widely known than it well deserves to be.

About the time of the appearance of this volume, he was appointed
Secretary of the American Iron Association of Philadelphia. In
this situation it was one of his first duties te collect accurate
statistics of the iron-industry of the United States. For this
purpose he not only carried on a voluminous correspondence, but
personally visited many of the ironworks himself, besides sending
one or two assistants to others. The results thus accumulated
were embodied by him in an important volume of nearly 800 pages,
‘The Ivon-Manufacturer’s Guide,’ which contained many maps and
a large amount of original discussion supplied by himself.

At the beginning of 1858 he was elected Librarian of the
American Philosophical Society, and thus began an intimate asso-
ciation with this distinguished institution which lasted to the end
of his life. He subsequently became one of the Secretaries, and
for many years was Vice-President, until he declined re-election in
1897. His devotion to this Society led him to work unweariedly
on its behalf, and to stimulate others in the furtherance of its
scientific reputation. In 1859 he became permanently Professor oi
Mining in the University of Pennsylvania.

For fifteen years from that date he was mainly occupied in
making surveys and reports for public companies and private in-
dividuals. ‘These labours involved much travelling and exposure,
as well as much hard work indoors in the preparation of his maps
and Reports. It is almost incredible that he could have turned

liv PROCEEDINGS OF THE GEOLOGICAL society. | May 19c4,

out so vast an amount of material in the time. Some of this
material was published and is of excellent quality, but a great deal
of it never saw the light after the object was attained for which it
was prepared. It is recorded that when he was sent by a Boston
company to survey some lands in the Cape-Breton coal-field, he
measured the strata, bed by bed, and in order to complete his
section with accuracy, was let by a rope down the face of a high
cliff. When at one time he seemed to be approaching dangerously
near the verge of the precipice, one of his faithful and admiring
attendants, fearing for his safety, took the precaution to knock him
down, and then apologized for his apparent rudeness.

At length, in the middle of 1866, his health gave way so com-
pletely under the strain of this overwork, that he was compelled to
seek rest and refreshment for two years in Europe, during which he
spent some time in Egypt. By the spring of 1868 he was once more
at his home in Philadelphia, but still unfit for much mental exertion.
In 1872, the University gave him the professorship of Geology and
Mining and made him Dean of the Scientific Department. Three
years later he was chosen Dean of the Towne Scientific School.
These University avocations kept his hands sufficiently full of work,
when, in 1874, he received the chief appointment of his life, that
of State Geologist of Pennsylvania. He had passed through thirty-
tive years of geological experience, and was now in his fifty-fifth year.
Though the official emoluments of the post were small, compared with
the income that he had been deriving from his private practice, he
at once accepted the appointment and threw himself with all his
wonted enthusiasm into the work of doing for his native State what
he had long wished to see done. He would now have the oppor-
tunity of making a thorough survey of a region so full of geological
interest and economic importance. How well he fulfilled the task
which he set before himself, and to which he devoted the unceasing
labour of some twenty strenuous years, those geologists can best
appreciate who have made acquaintance with his voluminous
Report. At last, worn out with his exertions, he had, in 1898, to
lay down the pen, when the last coping-stone of the great work of
his life had still to be placed.

‘The printed reports and map-atlases of the Second Geological Survey
of Pennsylvania extend to no fewer than 120 volumes. Throughout
these the hand of J. P. Lesley is everywhere apparent. He was
the life and soul of the enterprise, firing his subordinates with some
of his own ardour, training them in his methods of observation and

Vol. 60. ] ANNIVERSARY ADDRESS. ly

topography, editing and sometimes necessarily re-writing their ill-
expressed reports, but generously giving them full credit for all
_ their work, even where much of it might have been his own. The
volumes of the Final Reports, more than half of them from his pen,
present a singularly impressive picture of the extent and value of
a Survey which will be classic in geological literature, and will form
the noblest monument to the genius of J. P. Lesley.

He remained in Philadelphia for three years longer, until the last
volume of the Survey publications had been issued. Thereafter, in
the summer of 1896, he removed to the village of Milton, where
nearly fifty years before he had been pastor, and where he had
recently spent his summer holidays. In that cherished retreat, so
full of tender associations, he spent the remaining years of his life,
slowly growing feebler, until on the evening of the 1st of last June
he passed away.

Lesley was upwards of 6 feet high and, at least in his later
years, broad in proportion. His face, with its large well-formed
nose and mild eyes, was marked by a strong individuality in which
firmness and kindliness were equally represented. He had great
powers of conversation, and a remarkably winning manner which
irresistibly attracted those who were thrown into personal contact
with him. I shall retain as long as memory serves me the re-
collection of him in the midst of his Philadelphian home, with his
charming wife, his two daughters, his piles of cases of maps and
reports, and his geological assistants chivalrously on the alert to
anticipate his wishes and to carry out his instructions.’

He had been elected a Foreign Correspondent of our Society in
1866, and was promoted to the rank of Foreign Member in 1887.

Within the last few weeks geological science has sustained a
grievous loss by the death of one of its greatest masters—the
illustrious Karn ALFRED von Zirret. Although for several years
past he had not been in robust health, yet his keen and kindly
eyes retained still so much of their old brilliance, his interest
in the progress of his favourite studies continued to be so lively,
and the charm of his personal intercourse remained so delightfully
unimpaired, that his wide circle of devoted friends could not but

1 In preparing this notice of J. P. Lesley the fullest use has been made of
the facts gathered together by Mr. B.S. Lyman in an excellent Biographical
Notice (with an admirable portrait), published in the ‘Transactions of the
American Institute of Mining Engineers,’

lvi PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

hope that a career so full of distinction, of usefulness, and of
sympathy might still be prolonged for much further achievement.
But this was not to be. Full of honours and surrounded with
universal esteem and affection, he has passed ‘to where beyond
these voices there is peace.’

Born at Bahlingen in Baden on September 25th, 1839, Zittel
at the age of 18 proceeded to Heidelberg to study natural science.
There, under the inspiration of Bronn and C. Leonhard, he was
attracted more especially to geology and paleontology. After
taking his degree of doctor, he spent a year in Paris, in order
to profit by the instructions of the illustrious Hébert, to make
himself practically acquainted with the rich fossil treasures of the
Tertiary formations of that region, and to enlarge his knowledge
by excursions into some of the most interesting and instructive
parts of France. In 1861, having completed his student years, he
became one of the volunteer assistants in the Geologische Reichs-
anstalt of Vienna: and two years later was formally attached to
the University of that city as Privat-dozent. He was then ap-
pointed to the position of assistant in the Hofmineralien-Kabinett,
which is now the great Natural History Museum. Having declined
the offer of a professorship at Lemberg, he in 1863, when only
24 years of age, accepted the Ordinary professorship of Mineralogy,
Geognosy, and Paleontology at the Polytechnikum of Carlsruhe.
Two years thereafter he married the eldest daughter of J, W.
Schirmer, landscape-painter and director of the art-school, and
began that happy domestic union in which he rejoiced to the end
of his life. In the autumn of 1866 he received a great mark of
distinction in being invited to succeed Oppel in the chair of Palzeon-
tology in the University of Munich and in the keepership of the
National Paleontological Collection. In 1880 geology was added
to the curriculum taught by him; and in 1890, on the death of
Schafhiiutl, he succeeded also to the keepership of the National
Geological Collection. In June 1899 his distinguished scientific
position was fitly recognized by his being chosen to replace
Pettenkofer, as President of the Bavarian Academy of Sciences
and Keeper of the great scientific collections of the State. It was
in Munich, amidst the wonderful collection of extinct animals which,
largely by his own patient industry, tact, and skill, has been
gathered together there, that his life-work was mainly accom-
plished. Under his enlightened guidance that city became one of
the chief centres of palseontological research and progress.

Vol. 60. | ANNIVERSARY ADDRESS. lvil

The mere list of Zittel’s published papers shows his unwearied
energy and the wide range of his acquirements. This brief notice
cannot be more than a necessarily-imperfect and inadequate account
of his scientific achievements. Looking at them as a whole, we are
struck with their breadth of view, their originality of treatment,
and the complete command which they evince of the whole litera-
ture of every subject with which they deal.

His training having been so wide and so thorough, he was able

throughout his career to take up the consideration of each branch
of the geological sciences with full knowledge of its relations to
all the other branches. His mental grasp, his scientific insight,
and his faculty of luminous arrangement and clear exposition, are
strikingly displayed in his great work, the ‘ Handbuch der Paleon-
tologie.’ The first part of this treatise appeared in 1876, and the
last of its five massive volumes was issued in 1893. He thus spent
upon it some seventeen of the best years of his life. It was no
mere compilation. Almost incredible as the task may appear which
he undertook, he entered in turn upon the detailed study of each
great zoological group, and made himself so thoroughly master of it
and of its connected literature, that he could write upon it with the
ripe knowledge and full authority of an expert, competent to revise
the work of his predecessors. He was thus in a position to present
an ordered classification of the fossil groups, and to show their
affinities more clearly than had been done before. Hence his
volumes at once took their place as the great work of reference
for modern paleontologists, who came to look up to him as their
inspiring teacher, and to Munich as the Mecca towards which their
pilgrim-steps should be directed.

The department of paleontology to which Zittel gave perhaps
most exhaustive attention was that of the Fossil Sponges, his
treatise on which probably embodies his most important original
research. The group of Sponges had not been properly understood
or arranged when he entered upon its study, but he worked out the
true principle of classification of these organisms, applicable equally
to the extinct and to the living forms.

He took much interest in the region of the Libyan Desert. The
geological introduction to the first volume of that important work,
‘ Beitrige zur Geologie und Paleontologie der Libyschen Wiiste ’
(1883), was written by him. In 1896 he renewed his interest in
African geology by accompanying the excursion of the Geological
Society of France to Algeria, which he greatly enjoyed.

VOL. LX. €

lvili PROCEEDINGS OF THE GEOLOGICAL sociETy. [May 1904,

Among Zittel’s contributions to scientific literature a prominent
place must unquestionably be given to one of the publications of
his later years—his admirable ‘Geschichte der Geologie und
Paleontologie, which appeared in the summer of 1899. Various
attempts had previously been made to present a connected account
of the progress of geology, but most of these dealt with the earlier
periods of the science and were written before the extraordinary
development, in the second half of last century, of our knowledge
of the history of the earth. Zittel, while treating luminously of the
older researches, set himself the formidable task of digesting the
literature of geology and paleontology down to the end of last
century, and presenting to the world an ordered narrative of the
advances made in the several departments of these great domains
of natural knowledge. While it is difficult to exaggerate the
magnitude of this task, it is hardly less so to overpraise the success
with which the task has been accomplished. Turning everywhere
to the original sources of information, Zittel has been able to place
in a new light the enquiries of the ancient observers and those who
flourished in the heroic age of geology before the third decade of
last century. He shows the relations of the work achieved by a
host of labourers all over the world, and prepares the reader for
the more detailed discussion of the striking amplification of geolo-
gical effort in all directions during the rest of the century recently
closed. In none of his writings does he manifest more impressively
his breadth of view in natural science, his wide sympathy with
every line of scientific advance, the calm logical attitude of his
mind, the range of his knowledge, and the deftness of his literary
skill in marshalling so vast a body of facts in clear and interesting
order. His volume must form part of the library of every geologist ;
and to no book will the student of the future more frequently turn
for information and guidance through the crowded literature of
geology.’

On the 4th of October last Zittel was knocked over by a bicyclist
in the street, and his right knee sustained such injury as to confine
him to bed for several weeks. About two months later he acci-
dentally further injured the wounded knee. This bodily affliction,
coming after the deep mental distress into which he had been

‘ An excellent translation of this work, somewhat abridged, has been pub-
lished, with Zittel’s approval, by Mrs. Ogilvie-Gordon (a former pupil of his),
under the title of ‘ History of Geology & Paleontology to the End of the
Nineteenth Century ’ Contemporary Science Series, London, 1901.

Vol. 60. | ANNIVERSARY ADDRESS. lix

plunged some time before by the tragic death of his son-in-law,
proved too much for a frame now much enfeebled by cardiac
complications, and he passed quietly away on the night of the 5th
of January, 1904.

Few men in our time have been more widely known and
esteemed among the geologists of Europe and America than
Karl von Zittel. Though he stood in the front rank of science,
the most universally accomplished paleontologist of his day, no
one could be more modest and retiring. None could with more
generous devotion, with more kindly guidance, or with wiser
counsel encourage the younger men and women who looked up to
him as their master. Great as was his scientific eminence, the
beauty of his character was if possible greater still. He has left
to the rising generation a noble example of a brilliant man of
science, unwearied in activity, skilful and graceful as a writer,
genial and stimulating as a teacher, sympathetic and helpful as a
friend.

Zittel was elected a Foreign Correspondent of our Society in 1883,
and became a Foreign Member in 1889. ‘The highest distinction
which it lies in the power of the Council to bestow, the Wollaston
Medal, was awarded to him in 1894.

By the death of Atpnonse Francois Renarp geologists in our
islands have been deprived, not only of one of the most eminent of
their fellow-workers in the petrographical department of their
science, but of the foreign geologist who (by reason of his frequent
visits to this country) was probably personally known more widely
amongst us than any of his contemporaries on the Continent. Bya
large number of the Fellows of this Society, his loss has been felt
as that of a friend whose cheery, beaming face and interesting talk
were always welcome. He was born of modest parentage at
Renaix, in Eastern Flanders, on September 27th, 1842. He received
his early education in his native town, and then became clerk to a
manufacturer there; but a Catholic priest, having been struck with
the lad’s bright intelligence, persuaded him to continue his education
and offered to defray his expenses. This generous recognition
formed the turning-point in Renard’s career. Beginning with the
study of the humanities at the Episcopal College of Renaix, he con-
tinued it at the Jesuit College of Turnhout, until in 1863, at the
age of 21, he entered upon the noviciate of the Society of Jesus at
Tronchiennes. From 1866 to 1869 he acted as superintendent

e2

Ix PROCEEDINGS OF THE GEOLOGICAL sociery. [May 1904,

at the Collége de la Paix, Namur. In 1870, however, his scientific
career was begun by his being sent to the Jesuit Training College
at the old abbey of Maria Laach, by the side of the Laacher See in
the Eifel, for the purpose of studying philosophy and the sciences.
Up to that time he had paid no attention to geology. Placed in
the midst of one of the old craters of that interesting volcanic
region, this seminary was well fitted to kindle in any receptive
youth a desire to know something of the history of the earth.
When I visited it a few years before Renard came thither, I was
astonished to find the equipment for teaching mineralogy, petro-
graphy, and geology so efficient. Herr Theodor Wolf, who has since
become widely known from his researches in Ecuador, was one of
the inspiring staff of teachers at the Abbey, until its suppression by
the Prussian Government, and it was doubtless largely by his
example and influence that Renard was drawn into geological
investigation. The young student of philosophy became an active
and eager member of the excursion-parties which were organized
at the Abbey for the exploration of the volcanoes of the surrounding
country. And there can be no doubt that it was these years at
Maria Laach which finally determined his bent into the domain of
petrography.

A brief interruption of his studies was caused by the Franco-
German war, during which he retired to Belgium and became
superintendent in the College at Tournai. But returning to the
Laacher See, he continued his pursuits there, until in 1873 he took
a third year of philosophy and science at Louvain. ‘The following
year, at the age of 30, he received the professorship of Chemistry and
Geology in the College of the Belgian Jesuits at Louvain. Mean-
while his clerical training still continued. He studied theology as
as well as lectured on science, and in September 1877 was ordained
a priest. About the same time, his scientific abilities were recog-
nized by his being appointed one of the Curators of the Royal
Natural History Museum, Brussels; but though he came to reside
in the capital, he continued to give his lectures at Louvain until
1882, when he relinquished them and devoted himself to his official
work in the Museum. ‘There he remained until, when the Chair of
Geology at the University of Ghent became vacant in 1888, he
received that appointment, and held it up to the time of his death.

It is now nearly thirty years since Renard began to publish the
results of his scientific investigations.. His first essay dealt with the
plutonic rocks of his own Ardennes. In association with the late

Vol. 60. ] ANNIVERSARY ADDRESS. lxi

Charles de la Vallée-Poussin, he wrote the important monograph on
the mineralogical and stratigraphical characters of the rocks called
‘plutonic’ in Belgium and the French Ardennes, which was presented
to the Belgian Academy in 1874, and appears among the ‘ Mémoires
Couronnés’ of that institution. From that time onward he continued -
to give to the world other papers on Belgian rocks, among them an
interesting account of the minute structure and mineralogical com-
position of the whetslates, which he showed to abound in garnets.
He described likewise the phthanites of the Carboniferous Limestone,
and pointed out the distinctive characters of the calcite and dolomite
in the same formation. But the most notable of these contributions
to the geology and petrography of his native country were those in
which he discussed the phenomena of regional metamorphism, as
exhibited by the phyllades and the garnetiferous and amphibolitic
rocks. Confirming the general accuracy of the previous observa-
tions of Dumont, he regarded the distinct metamorphism of that
region as the result of intense mechanical disturbance, with accom-
panying chemical and mineralogical re-arrangements. In recent
years, having widened his experience of the problems of metamor-
phism, he was inclined to question the validity of his earlier
conclusions, and was rather disposed to think that the alteration
of the rocks might be due really to contact-metamorphism, though
the invading igneous material had not yet made its appearance
at the surface during the prolonged denudation of the rocks.
Prof. Gosselet, whose great work on the Ardennes marks him
out as the chief authority on the geology of that region, strongly
opposed this change of opinion, and contended for the essential
accuracy of the earlier deduction.

Renard’s published papers at once attracted attention, both among
petrographers and stratigraphers. They showed him to be a
capable chemist, and at the same time to have acquired a command
of all the most modern resources of investigation with the micro-
scope. But they further proved that he was no mere worker in a
laboratory or museum, for they evinced that he had accustomed
himself to study the rocks in the field, to examine their strati-
graphical relations, and to take broad and enlightened views
regarding their origin and history. His writings had gained
so much approbation m this country, that when the various
treasures brought home by the Challenger-Expedition were par-
titioned among recognized experts for determination and de-
scription, the petrographical specimens were entrusted without

Ixii PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

hesitation to Renard. He was likewise associated with Sir John
Murray in the investigation of the voluminous series of deposits
brought up from the bottoms of the various oceans traversed during
the course of that vessel’s voyage round the world. Numerous
communications of singular novelty and importance continued to be
published, as the outcome of this conjoint study, for some twelve
years. At last, the results of the whole prolonged and laborious
research were summed up in full detail in the great monograph on
the ‘ Deep-Sea Deposits,’ which forms to the geologist, perhaps the
most valuable of all the massive quarto volumes of the Challenger-
Reports. There can be no doubt that this work will become a
classic in the literature of Oceanography, and will be looked on as
practically the starting-point for all subsequent research on the
subject of which it treats. Every geologist is now familiar with
the more striking additions to our knowledge of the abysmal
sediments, made by these researches of Murray and Renard—the
detection and description of cosmic dust, which as a fine rain
slowly accumulates on the ocean-floor ; the development of zeolitic
crystals on the sea-bottom at temperatures of 32° and under; and
the distribution and mode of occurrence of manganiferous concretions
and of phosphatic and glauconitic deposits on the bed of the ocean.

Renard was elected a Foreign Correspondent of this Society
in 1880, immediately after the commencement of the publication
of his contributions from the Challenger-stores. He became one
of our Foreign Members in 1884, and in the following year he
received our Bigsby Medal. His close connection with the
Challenger-work and those who conducted it in Scotland was
appropriately recorded by his election into the select number of the
Honorary Fellows of the Royal Society of Edinburgh.

From the time of his entering the priesthood he was everywhere
known as the Abbé Renard, and until not many years ago continued
to wear the clerical dress even in his visits to this country. When
he came to Scotland in the early years of his connection with the
Challenger-work, I saw much of him, and he now and then joined
me in a geological excursion, which one year we prolonged through
the North-Western Highlands as far as Cape Wrath, where he passed
the night at the lighthouse-keeper’s, sitting on a wooden chair with
his arms and head resting on the table’ On that and on other
occasions I had long talks with him on theological as well as
geological and other matters, and could see even then that his
views were much more liberal and advanced than might have been

Vol. 60. | ANNIVERSARY ADDRESS. Ixili

looked for in a Jesuit father. His hold on the orthodoxy of the
Latin Church grew weaker as his scientific vision increased in
strength and breadth.

The first overt act of renunciation of his ecclesiastical ties
appears to have been taken by him in 1884, when he formally
left the Society of the Jesuits. I had previously understood from
him that he had never taken the final step that would have
completed his attachment to that order, and that he was still at
liberty to go no farther. In leaving the Jesuits he did not,
nevertheless, leave the Church, but became thenceforth one of the
secular clergy. In the end, however, the struggle between the
influence of all the earlier associations of his life and the claims of
what his reason now convinced him to be the truth, became too great
to be longer endured, and he determined to sever his connection
with Roman Catholicism. Had he gone no farther than a public
announcement of this change of religious belief, the outcry against
his apostasy would, in such a country as Belgium, have doubtless
been loud and long. But, as if to leave no doubt of his secession,
he, on March 21st, 1901, married Mlle. Henriette van Gobelschroy.
That one who had been all his life a priest should take such a step
could not but intensify the persecution that was gathering around
him. Many bitter, unworthy, and baseless reproaches were heaped
upon him, and many old and intimate friends now shunned him.
A man of his kindly nature could not but feel deeply the insinua-
tions and misrepresentations to which he was subjected. Perhaps
I may be allowed to translate a few lines from the last letter that I
received from him, which may show how he himself looked upon
the step that he had taken. After thanking me for my good wishes
on what he calls ‘my act of moral emancipation and my marriage,’
he proceeds thus :

‘If I had had an opportunity of seeing you I should have been able to tell
you in detai! the struggles through which I have passed in order to gain this
precious human liberty, which at last I enjoy. To-day a great calm reigns
within me, such as one feels when one has done one’s duty, and I have now,
moreover, the consolation which only a family-hearth can give. I can enjoy
my lot and throw back upon my past such a look as the traveller, arrived near
the end of his journey, may cast on the rough and perilous paths which now
lie behind him. Different roads lead to the truth, which must be the beacon
light towards which we aim, and, how thick soever may be the night of
falsehood and error, those who will can reach that goal, I have now the deep
happiness of being one of these.’

A fatal disease, which had been insidiously making progress in

XiV PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

his constitution for some years, and for which he had undergone
more than one operation, at last carried him off on the 9th of last
July, in the 61st year of his age.

Frerix Karrer was born on March 11th, 1825, in Venice, which
was then within the dominions of Austria. His father died when
he was only four years old, and his mother thereupon removed
with him, her only child, to Vienna, where he was educated and
where he spent the rest of his long life. After a training in
philosophical and legal studies, he received an appointment in the
War Department and soon obtained promotion. But his duties
there seem to have been little to his taste, and as his mother
possessed means which, though not large, sufficed for the modest
maintenance of her little household, he determined, when 32 years of
age, to abandon an official career and to live an independent life. He
had long been fond of stones, and often in his beyhood, to the vexation
of his mother, would come home with his pockets full of them.
He now gratified this propensity by attending the lectures of the
illustrious Suess, who was then a young Docent in the University,
teaching paleontology and geology. In Vienna, men of science
who have incomes sufficient to enable them to gratify their scientific
tastes, without being tied to a professorship or other official post, are
much fewer than they are in this country. There can be little
doubt that Karrer’s unattached freedom not only enabled him to
choose the pathways of research that best pleased him, but gave
him a peculiar place among his contemporary geologists and
paleontologists in Vienna.

He was soon attracted by the fossiliferous Tertiary deposits of
the Vienna Basin, and was gradually led to study their minuter
organisms, more especially their foraminifera. To enable him
to pursue this line of investigation, he obtained the use of a
window in one of the halls of the Hofmineralien-Kabinett. His
friend Theodor Fuchs, with whom he was so intimately asso-
ciated in that institution, relates that Karrer’s equipment at
his window consisted only of a broad board and a few boxes,
yet that, with his practical habits and scrupulous orderliness, he
was able there to gather together and stow away everything that
was requisite for his work, coming day after day as punctually as
any official. He sat at that window-board for more than five-and-
twenty years, until the transference of the Collections to the new
palatial Museum. Nearly the whole of the personal staff of the

Vol. 60. | ANNIVERSARY ADDRESS. lxv

Institution had changed during that time. Only Karrer remained
steadily in his place, untouched by the passing years, the centre
and living chronicle of the Kabinett.

His first paper, on the structure of the Eichkogel near Médling,
was published in 1859, in the ‘Jahrbuch’ of the Geologische
Reichsanstalt. His attraction towards the investigation of the
Foraminifera resulted in a long succession of memoirs, which formed
his most important contribution to science. In association with
Fuchs, he made many excursions to study the geology of the region
around Vienna, and the two friends gathered together the results of
their researches in a series of ‘ Geological Studies in the Tertiary
Formations of the Vienna Basin,’ which appeared in the * Jahrbuch’
from 1868 to 1875. The underground water-system of the same
region in its geological relations likewise occupied much of his
thought, and formed the theme of a number of papers by him.
Chief among these is the elaborate monograph which forms the 9th
volume of the ‘ Abhandlungen’ of the Reichsanstalt, published in
1877. In this work, which is a study of the Tertiary formations
on the western border of the Alpine part of the Vienna Basin, he
discusses the geological relations of the various thermal and other
springs in that basin, and gives sections illustrative of the structure
of the ground traversed by the water-channels, together with
copious lists of the organic remains obtained from the strata therein
represented.

Karrer likewise devoted his energies to the development of some
departments of industrial geology, particularly in regard to building-
materials. He took an active part in the affairs of several Societies,
more especially of the Scientific Club, of which he was for many
years Secretary. He was enrolled among the Foreign Correspondents
of our Society in 1890. Eminently courteous and ever ready to assist
others, he was a great favourite with all who knew him. He was
twice married. His first wife died without children, but by his
second marriage he had ason and two daughters. All through
his life he enjoyed remarkably-good health. He was never seriously
ill, and at the end of sixty years he retained the bearing of a youth.
In 1902 he began to suffer from dyspepsia, and an attack of
influenza still further afflicted him. In the early spring of last
year he was so far better as to be able once more to visit the
Museum; but it was now as an enteebled old man. He died
calmly on the morning of April 19th, 1903.

Ixvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. | May 1go04,

The death of Witt1am Tatpor Avetinr severs one of the few
remaining links connecting this generation with the heroic age
of English geology. Born in 1822, he joined the staff of the
Geological Survey under De la Beche in 1840, when he was only
eighteen years old. At first he was stationed for a short period in
Somerset, on the Mendip Hills, but soon afterwards was transferred
to South Wales, the survey of which had now been begun. At
Fishguard he had as one of his associates Andrew C. Ramsay, who
had been appointed to the staff a year after him. In those days
such detailed mapping as is now required had not been dreamt of.
De la Beche, having made a masterly set of maps of the region
south of the Bristol Channel, was anxious that the country on the
north side of that estuary should be surveyed in the same broad,
generalized, and rapid manner. Nor in the state of knowledge of
the rocks at that time would any more detailed style of mapping
have been practicable. Nothing was known of the subdivisions of
the older Paleozoic rocks there, and the condition of English
petrography did not admit of any detailed treatment of the igneous
masses,

The surveyors were thus enabled to push on with comparative
rapidity across Southern and Central Wales. The older Palseozoic
rocks were represented on the maps by one colour, and no attempt
was made to discriminate the varieties of the igneous rocks. But
in the course of years the necessity for greater detail came to be
strongly impressed on the minds of the more experienced members
of the staff, particularly Ramsay, Aveline, Jukes, and Selwyn. The
masterly researches of Sedgwick and McCoy had shown that what
had been taken for Lower Silurian strata belonged really to the
upper division of the system. Ramsay, realizing the great strati-
graphical importance of the striking break between the two series
at Builth, had joined with Aveline in reading before this Society,
in 1848, a ‘Sketch of the Structure of Parts of North & South
Wales,’ in which the nature and significance of this great uncon-
formity and overlap were clearly stated. Aveline subsequently traced
in North Wales the persistent group of the Tarannon Shales, and
showed how distinct is the horizon that they occupy. ‘The necessity
for some revision of the early published maps was recognized by
Ramsay, long before he could obtain the consent of De la Beche to
undertake it. At length, as the last official act of his life, the
illustrious Director-General, then near his death, agreed that the
revision should be carried out. Aveline and J. W. Salter had been

Vol. 60. | ANNIVERSARY ADDRESS. xvii

employed to trace the boundary-line between the Lower and Upper
Silurian formations in Shropshire and the adjacent tracts of Wales ;
and Aveline was now commissioned, in 1855, to proceed to South
Wales to correct the obvious inaccuracies of the maps of that region,
to insert important stratigraphical boundary-lines, and to revise the
igneous rocks, especially separating the basic from the acid series.
At the end of the letter of instructions sent to him by Ramsay came
this injunction: ‘ Finally, do not spare horse-flesh or car-hire to
do it quickly.’

When Ramsay was making his preparations in 1854 for com-
mencing the Survey in Scotland, he thought at first of taking Aveline
as his chief assistant in the work, but the pressure of the revision
in South Wales led to the abandonment of this intention and the
substitution of Mr. H. H. Howell in his stead. When I first joined
the Survey in 1855, the original intention of the Local Director had
been to place me with Aveline in Pembrokeshire; but this idea
was likewise abandoned, partly from the need for pushing on the
Scottish Survey, and partly from the good progress already made in
the South Welsh revision. But I well remember the account of
Aveline given me at that time by Ramsay—a tall, dark, silent, big-
booted man who strode with gigantic steps over the hills; whose
eyes seemed always directed towards the front, but never let any-
thing escape them ; who wrote like a schoolboy, but was the ablest
field-geologist on the staff. Ramsay’s diary contains an entry in
which, referring to a meeting that had been arranged with Aveline
among the hills of North Wales, he draws the following picture of
his colleague :—

‘While loitering about, taking a final look, I spied Aveline coming down
anxiously, with his hat pulled over his eyes, his coat-collar turned up, his
gaiters hanging about his heels, taking long strides and looking out ahead, but
never holloaing, as another man might have done.’

His silent demeanour passed into a proverb in the Survey. It
probably reached its climax when, in company with one of his
junior colleagues, he spent a whole day among the Welsh hills, and
his conversation was said to have consisted only of two words. In
the morning, as he passed a crag of rock, he tapped it with his
hammer, and remarked ‘Grits.’ In the evening, on the way home-
wards, he had to chip another block, and again broke silence with
‘more Grits.. And yet there were times when, in congenial com-
pany, his natural reserve and taciturnity would aimost melt away,
and when his eyes would glisten as he told some recollection of old

lxvui PROCEEDINGS OF THE GEOLOGICAL sociETy. [| May 1904,

Survey days. His gentle, kindly, modest nature made him a great
favourite among his colleagues and friends.

When in 1867 the organization of the staff of the Geological
Survey was enlarged and re-arranged, Aveline became what was
called * District Surveyor,’ and was entrusted with the charge of the
mapping of the Lake District. For the next fifteen years he con-
tinued to reside in that region, until on reaching the age of 60 he
claimed his retirement. Quitting the Survey in 1882, he retired to
his paternal property at Wrington, in Somerset, and lived there as a
country-squire, looking after his farm and attending to his family.
As he always wrote with difficulty and hardly ever save under official
compulsion, he made no contributions to science except his share in
the Survey Memoirs, and now and then a letter to the ‘ Geological
Magazine, when some published statement stirred him into un-
willing effort. Elected into this Society as far back as 1848, he
seemed almost to have already passed away from us when the
Council in 1894 awarded to him its Murchison Medal. This appro-
priate recognition of his long years of arduous toil in the service of
geology gave him the keenest pleasure.

He had found his Somerset home increasingly inconvenient, on
account of its distance from any centre of life, so that in the end
he gave it up and settled finally in London, where he spent his
last years and where he died on the 12th of May, 1903, at the age
of 81. |

The value of the geological work achieved by Aveline is not to be
estimated from the number or importance of the memoirs and
papers which he contributed to the literature of the science. As
terse descriptions of the local facts which he had observed, these
publications will always deserve attention. Most cf them are to
be found among the Sheet-Memoirs of the Geological Survey. He
was an admirable field-geologist, with a keen eye for geological
structure and a rare capacity for accurate mapping. It is by his
maps that the nature and importance of his scientific work must be
judged. No one who, with these maps in hand, has followed in his
footsteps among the crags of North Wales, can fail to recognize his
geological prowess. In the bede-roll of the Geological Survey few
names will stand out more prominently than that of William Talbot
Aveline.

Rosert EvrHermpGk was born at Ross, in Herefordshire, on
December 3rd, 1819. Having come in his youth to Bristol, he was

Vol. 60. | ANNIVERSARY ADDRESS. lxix

engaged in business there during his earlier years. But that he
employed his leisure in natural-history pursuits is evident from the
fact that at the age of 31 he was appointed Curator of the Museum
of the Philosophical Society of Bristol. With the facilities for
research which he then obtained, he made himself familiar with the
Secondary rocks and their fossils, so well developed in the region
around his home. His knowledge in this department of our science
was recognized to be so exceptional, that in the year 1857 he was
offered and accepted the post of one of the paleontologists in the
Geological Survey at Jermyn Street, under the leadership of
Murchison. At that time J. W. Salter, who was in the full vigour
of his work as paleontologist, took charge more especially of the
invertebrate paleontology of the Palzozoic formations; that of
the Secondary and Tertiary groups was accordingly now put into
the hands of Etheridge, who hkewise gave demonstrations to the
students at the Royal School of Mines under Huxley. He had pre-
viously had some experience in lecturing at the Bristol Mining School,
and in 1859 he published the substance of his prelections there in
the volume entitled ‘ Geology : its Relations & Bearing upon Mining.’
In 1863 he succeeded Salter as Paleontologist to the Survey.

All through his life Etheridge was singularly industrious, busy
at his various tasks, early and late ; but the published papers and
books which he has left furnish a wholly inadequate idea of the
amount of work which he accomplished. He was constantly engaged
in the details of a museum, determining, labelling, arranging, and
cataloguing specimens. Much of this labour was severe and unceas-
ing, but as it made little outward show it hardly, perhaps, received
the recognition which it deserved. Yet, had it been pretermitted,
the effects of the want of his skilled eyes and deft hands would soon
have been apparent in the cases of the Museum. Further, during his
connection with the Survey, he was charged with the preparation of
lists of fossils for the various Memoirs—a task demanding care and
accuracy, involving often much time and trouble, yet finally repre-
sented in print sometimes by but a few pages of text and a series
of tabular statements, buried in the appendix to an official pamphlet
composed of flimsy paper, badly printed perhaps with old broken
type, and sold not infrequently at a prohibitive price.

Yet, notwithstanding the claims of the Museum and Survey, he
contrived to find opportunity now and then to write a non-ofticial
paper on some of the subjects which came under his observation.
The. more important of these communications were read before this

xx PROCEEDINGS OF THE GEOLOGICAL socteTy. {May 1904,

Society. Among them was his elaborate account of the strati-
graphy of Devon, which he was induced to undertake at the request
of Murchison. Jukes had at that time promulgated certain views,
which the Chief looked upon as heretical, regarding the Devonian
system, and the Survey-Paleontologist was deputed to test their
accuracy. He spent many weeks on the ground, and came back
to support what had long been the orthodox faith. The world has
not accepted the contention of Jukes. No one, however, who has
attempted to understand on the ground the succession and tectonic
relations of the Devonian rocks of Devon and Cornwall, ean fail
to be convinced that whether the accepted view as to the order
of succession shal] ultimately be established by detailed mapping
or not, it was certainly founded in ignorance of the extremely-
complicated structure of the region. Even yet, after all these years
of patient investigation, reinforced more recently by the minute
field-researches of the Geological Survey, the stratigraphy of that
region of the country is far from having been unravelled and
understood.

Other papers by Etheridge during his Survey-career, to which
reference may be made here, are his account of the Dolomitic Con-
glomerate of the Bristol area, and more particularly his two Presi-
dential Addresses to this Society, embracing as they did an enormous
mass of detail which, though of temporary interest, has now little
more than a historical value. His position at Jermyn Street made him
au official referee, to whom specimens of fossils from all parts of the
world were submitted for determination. A number of his reports
on these were submitted to this Society, and are to be found in our
Quarterly Journal. As a notable example of the laborious tasks
which he undertook, allusion may be made here to his stratigraphical
and zoological ‘ Catalogue of British Fossils,’ wherein he attempted
to give the position of each species in the geological formations, in
systematic grade, and in scientific literature. Only the Paleozoic
portion of this work has been published, the Mesozoic and Kainozoic
portions remaining still in manuscript. These and all the other
similar works of Etheridge bear witness to his remarkable neat-
handedness. Page after page and table after table may be seen
clearly written out, with few or no corrections, and now and then
accompanied by a cleverly-drawn and coloured geological section in
illustration of some question of stratigraphy.

In 1881 Etheridge quitted the Geological Survey to accept the
post which was offered him of Assistant-Keeper of the Geological

Vol. 60. | ANNIVERSARY ADDRESS. xxi

Department of the British Museum, where he remained for ten
years until he retired from the public service in 1891. While
there he had a still ampler field for the exercise of his special
gifts. After his retirement, his mental activity remaining un-
impaired, he was employed in preparing and arranging in the
Museum a stratigraphical collection of British rocks illustrative of
the geological formations of our islands. This task afforded, again,
full scope for his facility in drawing neat and effective sections,
which, with coloured maps also constructed by him, make the
specimens greatly more interesting and instructive.

In his later years he was often consulted as an expert in
questions of water-supply, search for coal, and other cognate
subjects. Among these employments the latest, on which he was
engaged almost up to the time of his death, was the coal-boring at
Dover, in relation to which he acted as geological adviser to the
promoters, and where his knowledge of the Secondary rocks enabled
him to recognize each stratigraphical horizon that was pierced
before the boring-rods entered the Paleozoic formations.

Etheridge became a Fellow of this Society in 1854, while still
Curator of the Museum at Bristol. After he settled in London
he was a constant attendant at our meetings, and some of his
phrases and mannerisms are pleasantly remembered by his surviving
coutemporaries. He was elected into the Royal Society in 1871.
In 1880 he received the Murchison Medal, and in the same year
was elected President of the Geological Society. He was the first
recipient of the Bolitho Gold Medal of the Royal Geological Society
of Cornwall. His gentle, kindly nature gained him troops of
friends. He was ever ready to assist anyone who came to profit
by his knowledge and experience. Up to the last he had enjoyed
excellent health, and dined out with friends on the anniversary of
his birthday, on December 3rd. Soon thereafter, however, he
caught a chill, which rapidly developed into bronchitis, to which
he succumbed on the 18th of the same month, in the 85th year
of his age. <A representative company of his friends, among whom
were a number of Fellows of this Society, gathered round his
grave in the Brompton Cemetery, and saw him laid not far from
where his old chief Murchison rests.

In Maxwe tt Henry Crosz Ireland has lost her most distinguished
glacialist, one of the pioneers to whose labours we are not a little
indebted for the progress of glacial geology in the British Isles. He

Ixxil PROCEEDINGS OF HE @HOLOGICAL society. [May 1904,

was born in Dublin in 1822, was educated partly at Weymouth, and
took his degree of B.A. at Trinity College, Dublin, in 1846, and M.A.
in 1867. At the age of six-and-twenty he was ordained as a clergy-
man of the Church of England, and from 1849 to 1857 was Rector
of Shangton, in the south of Leicestershire. Having conscientious
scruples as to retaining an office which he had obtained under
the system of lay-patronage, he resigned the living, and then
became Curate of Waltham-on-the-Wolds, a village on the Jurassic
scarp between Melton Mowbray and Grantham—a position which
he continued to hold until, in 1861, soon after the death of his
father, he returned to Dublin, which capital thenceforth became
his permanent home.

He had already begun to study the geology of his native country.
As far back as the year 1863 he read to the Geological Society of
Dublin a paper in which he discussed the nature and origin of
slickensides. But it was the glaciation of the country that, from
the beginning of his career, especially fascinated him. In pursuit
of the trail of the old ice-sheets, he travelled far and wide over
[reland, and gained such a knowledge of the subject as enabled him
to present, for the first time, a luminous account of the evidence that
the island had once been cased in land-ice which moved off in all
directions to the sea. In the year 1864 he began his series of
glacial memoirs with one on the phenomena displayed in the district
around Dublin, which was read before the Geological Society there.
It will be remembered that, at that time, although a few British
pioneers had come to the conclusion that the phenomena of the
striated rock-surfaces all over these islands, and the origin and
distribution of the Boulder-Clay, could only be accounted for by the
action of sheets of land-ice, the great majority of the leaders as well
as the rank and file of our geological army still stoutly held to the
theory of submergence and floating ice. Maxwell Close, however,
from the evidence which he obtained among the Wicklow Hills, soon
became convinced that the facts could only be explained on the
land-ice theory; and he stated clearly and cogently jthe grounds
upon which this conviction rested. He inferred, from the striated
surfaces around Bray, that the ice in that district must have been
more than 1120 feet thick ; while, from the occurrence of transported
and striated stones, he concluded that it was probably much thicker,
reaching at least to a depth of 1760 feet, if indeed it did not sweep
over the summit of Lugnaquilla itself, which is 3039 feet above the
sea. Asa proof of his alertness and sagacity as an observer, it may

Vol. 6c. | ANNIVERSARY ADDRESS. lxxill

be added that in this first of his glacial papers he noticed the
occurrence of striated pavements in the Boulder-Drift, and adduced
them to show that, although the ice had exerted enormous erosive
power on solid rock, it had also sometimes fiowed over its floor of
detritus.

He must have spent a singularly-busy time during the next two
years, scouring Ireland from one end to the other in search of the
traces of the vanished ic e-sheets; for on March 14th, 1866, he read
his admirable and classic paper, ‘ Notes on the General Glaciation
of Ireland,’ which for the first time gathered together and discussed
the striking evidence which that country presents of having been
the seat of a continuous mass of land-ice. He was now able to
embody on a map the results of his journeys, combined with those
already obtained by other observers, and to show the chief centres
of dispersion and the directions in which the ice streamed outward
to the sea. He was probably the first geologist in these islands to
realize that, although the mountains undoubtedly helped to accumu-
late the ice, they were not indispensably necessary for the formation
of a thick ice-covering for he showed that the great central plain
of Ireland had undoubtedly been buried under such an icy mantle,
which streamed outward in different directions. Reviewing the
whole subject, and impartially balancing the arguments for the
various explanations that had been proposed, he once more demon-
strated the overwhelming evidence in favour of the action of land-
ice as the origin of the glaciation and of the Boulder-Drift.

Yet Maxwell Close was no bigoted partizan. He admitted the
submergence of the country and the action of floating ice during
part of the Glacial Period. In 1874 he called attention to the
high-level shell-gravels which had long been known to lie upon
the hill-slopes near Dublin up to heights of 1000 and 1200 feet.
He believed that these deposits, shells included, had been trans-
ported to their present positions by floating ice when the land was
sunk to such depths beneath the sea. He thought that they had
come from somewhere to the north-west, and from the character
of the few and highly-fragmentary shells he inferred that they
pointed to the former existence of rather more boreal conditions
than those which now obtain in the region.

In association with Mr. G. H. Kinahan, Close published in
1872 a more detailed account of the glaciation of the district of
Tar-Connaught, between Castlebar and Galway Bay. Mr. Kinahan
had been engaged in the mapping of that region by the Geological

VOL, LX. F

Ixxiy PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

Survey, and embodied in a map the observations made by the Survey
of the rock-strie and drumlins of Boulder-Drift. The data thus
supplied enabled Maxwell Close to discuss, in his clear logical
manner, the phenomena of ice-action in a small localized centre of
dispersion.

Geologists are further indebted to him for his able advocacy of
the great extent of geological time, in opposition to the limitations
sought to be imposed by the physicists. In 1878 he presented
to the Dublin Meeting of the British Association a brief com-
munication on this subject, wherein he contended that some of
the physical arguments on which reliance had been placed were
unsatisfactory and inconclusive, and left geology still in possession
of ‘her own strong and unrefuted arguments for the great extent of
geological time.” He discussed the question at greater length in his
address as President of the Royal Geological Society of Ireland, in
February of the same year. In this suggestive essay he showed
his marked qualifications for dealing with scientific problems that
required mathematical and physical treatment.

In 1878 Mr. Close was elected Treasurer of the Royal Irish
Academy, an office which he continued to fill with zeal and
efficiency, until he resigned it in March last. He took an active
interest in the Academy’s business; likewise in that of the Royal
Dublin Society. But it was the activity of a quiet retiring nature,
careless of self, and only concerned for the welfare of the institutions
themselves and of their individual members, as well as for the
advance of true science. He was elected a Fellow of our own
Society in 1874. He died on September 12th, 1903, respected by
all who ever met him and beloved by those who were privileged

with his friendship.

Wittiam Henry Corrietp, who became a Fellow of this Society
in 1866, was born on December 14th, 1843, and died on the 26th
of August last, in the sixtieth year of his age. He was educated
at the Cheltenham Grammar School and at Magdalen College,
Oxtord, where he obtained a Demyship in Natural Science at the
early age of seventeen. In his youth he received a bent towards
geological pursuits, inasmuch as in 1863 he was chosen by Daubeny
to accompany him in an excursion to Auvergne. He obtained in
open competition the Medical Fellowship at Pembroke College,
Oxford, took first-class honours in the Natural-Science Schools with
chemistry and geology as special subjects, gained the Burdett-Coutts

Vol. 60. | . ANNIVERSARY ADDRESS. lxxy

Scholarship in geology, and afterwards carried off the Radcliffe
Travelling Fellowship in medicine. He took the degree of M.B.
‘In 1868, and next year became Professor of Hygiene and Public
Health at University College, London. It was in that department
of applied science that he spent the remaining years of his strenuous
life, attaining in it a high position. Though thus led away from
the strictly-geological domain, he always retained his early interest
in our science, and availed himself of his opportunities of showing
the connection of geological structure with questions of sanitation.

Sir Cuartes Nicuotson, who died on the 8th of November last,
in his 94th year, became a Fellow of this Society as far back as
1841. After graduating in Medicine with high honours at the
University of Edinburgh, he went at the age of twenty-five to
Australia, where an uncle had acquired some property near Sydney,
and where he wished to ascertain whether he could himself settle.
Having decided to cast in his lot with the fortunes of the young
colony, he at first devoted himself with ardour and success to the
medical profession. Thereafter he acquired a partnership in a
sheep-station, and was gradually drawn into active participation
in all the social and political development of the community. He
became a member of the first Legislative Assembly of New South
Wales, and took such a leading part in its deliberations that he was
thrice elected Speaker of the Chamber. His interest in educational
progress was especially deep and enlightened. He had an active
share in the foundation of the University of Sydney, and was for a
number of years the Chancellor of that flourishing institution,
endowing it with many valuable gifts, some of which—such as the
collection of Egyptian antiquities, which he himself made in Egypt—
had a high educational value. He eventually returned to this
country, and spent the latter years of his life at the Grange,
Totteridge, Hertfordshire. He was knighted in 1852, and in 1859
was made a Baronet. Those who were privileged with his friendship
will cherish the memory of his kindly face, his keen appreciation of
humour, and his interest in everything relating to scientific and
educational progress.

JoHN ALLEN Brown will be long remembered for the unwearied
enthusiasm of his investigations of the Paleolithic gravels of
Middlesex. Born in 1831, he succeeded his father as a diamond-
merchant. At first, his tastes appear to have been rather

f 2

Ixxvi PROCEEDINGS OF THE GEOLOGICAL socieTY. {May 1904,

geographical than geological, but eventually he was led to turn
his attention to the superficial deposits around his home at Ealing
which, as that suburb began to grow, were opened up in many
places. From this branch of enquiry he hardly diverged up to the
elose of his life. He succeeded in amassing a valuable collection
of stone-implements, which he arranged with much care and
thought. The results of his investigations were from time to time
embodied in communications to the Ealing Natural History Society
and other societies. But these papers were subsequently incor-
porated and enlarged into his work on ‘ Paleolithic Man in North-
West Middlesex,’ by which he will be chiefly remembered. After
a long and painful illness he died on September 24th last. He had
been admitted into this Society in 1886.

Witiram Vicary was born at Newton Abbot in 1811. When
a young man he went to London to gain further acquaintance
with the processes of tanning, his father being a tanner at
Newton. He established himself in the same business at North
Tawton, but retired from it many years ago, and thereafter lived at
Exeter. Having thus leisure and a competency, he was able to
indulge his tastes for scientific enquiry. A keen observer, he
spent much of his time in travelling and collecting, and formed
a fine assemblage of Devonian fossils which he bequeathed to the
British Museum. He called attention to the fossiliferous character
of some of the pebbles in the Budleigh-Salterton Pebble-Bed, and
presented to this Society a paper on that subject which, with
Salter’s accompanying description of the fossils, appeared in 1864
in the twentieth volume of our Quarterly Journal (p. 283). In the
same year he was elected a Fellow of this Society. He took interest
also in the rocks and minerals of his native county, at one time
fixing his attention on the igneous masses and at another on the
murchisonite-pebbles and boulders in the Triassic conglomerates.
For the purpose of aiding his examination of the fossil corals, he
obtained a series of recent species. Vicary gave freely of his know-
ledge, and helped many geologists in other ways. Although he wrote
little, he had wide scientific sympathies. Besides his geological work,
he interested himself in meteorological observations and was one of
the original contributors to ‘ British Rainfall,’ in the first volume
of which, published in 1860, he records a rainfall of 42:17 inches
at Exeter. He died at his home in that city on October 22nd last,
in his 92nd year.

Vol. 60.] ANNIVERSARY ADDRESS, xxvii

Cuartes Henry Garry, who became a Fellow of this Society in
_ 1862, was born on March 6th, 1836, and was educated at Trinity
College, Cambridge, where he took his B.A. degree in 1859 and
became M.A. in 1862. From his college-days onward he took a
lively interest in the natural-history sciences, especially zoology and
geology. Having ample means at his disposal, he was able, not
only to gratify his own tastes as a collector, but to assist the
progress of the investigations of others. Thus he was early
attracted to the Marine Laboratory at St. Andrews, established
under the Fishery Board, which was the first institution of the
kind founded in this country. Eventually he showed his apprecia-
tion of the value of the scientific work that was being accomplished
there, by offering £1000 to build a new laboratory to replace the
old wooden building which had originally been constructed as
a fever-hospital. Subsequently he doubled his donation. He
afterwards added still another £500 for furnishing and equipping
the establishment, and in the end doubled this subscription also.
His generous nature likewise led him to spend his money freely for
philanthropic purposes. Thus he built and equipped a hospital
for the sick near his home at East Grinstead.

He was himself a keen observer of marine life, and made
considerable collections among the Channel Islands and along the
southern coasts of England. Although he did not publish his
observations, he continually communicated them to those who took
interest in the same pursuits. With the Marine Laboratory at
St. Andrews he was thus in frequent communication, sending
notes of what he had himself noticed in Cornwall or elsewhere,
and receiving with lively interest reports of the progress of the
work at the northern station. He used to pay a visit to
St. Andrews every year, spending most of his time there in the
laboratory, until failing health prevented him from travelling
so far.

His residence at Felbridge Place; near East Grinstead, was a
charming house for a naturalist, surrounded with fine trees and
shrubs, haunted by birds of many kinds which were left in
undisturbed possession. Dr. Gatty was a Fellow of the Linnean
and Zoological Societies and of the Royal Society of Edinburgh.
St. Andrews showed its appreciation of his enlightened generosity
by bestowing upon him the freedom of the city, while the
University conferred upon him its degree of LL.D. He died on
December 12th, 1903, unmarried, in the 68th year of his age.

Ixxvill PROCEEDINGS OF THE GEOLOGICAL soctEty. [May 1904,

Marrnew Bett, one of the oldest Fellows of this Society, joined
our ranks as far back as 1845. He was born in 1817, and after
his education at Trinity College, Cambridge, passed his life quietly
but usefully at his home, Broom Park, Bishopsbourne, near
Canterbury. He filled the offices of Justice of the Peace and
Deputy-Lieutenant of the County of Kent, and was High. Sheriff
in 1850. He was sometimes urged to enter Parliament and to
contest the old East-Kent division, but he preferred the leisure and
retirement of the life of a country squire. He took a share of the
county-business, and acted as Director and Trustee of various
societies and institutions. He was a liberal benefactor to all the
good works that went on around him.

Witiiam Francis, although he never took an active participation
in the work of our Society, was a familiar friend of many of our
Fellows. Born in February 1817, he belonged to the heroic time
of geology, and was an eye-witness of the career of many of the
distinguished men by whom the success of our Society was early
assured. He received a large part of his education in France and
Germany, and acquired remarkable familiarity with the languages
of those countries. He took the degree of Ph.D. in 1842. His
scientific proclivities lay in the direction of chemistry and physics,
and he was one of the original members of the Chemical Society
In 1842 he founded the ‘Chemical Gazette, and nine years later
became one of the editors of the ‘ Philosophical Magazine ’—a charge
which he continued to fill until the end of his long life. In 1859
he also became one of the editors of the ‘ Annals & Magazine of
Natural History.’ His wide range of scientific attainments and his
sound judgment and great tact eminently fitted him for the editorial
duties which he so ably discharged. His qualifications for this work
were further augmented by his being during most of his life an
active partner in the widely-known printing firm of Messrs. Taylor
& Francis. He was elected into our Society in 1859. Some of
us well remember the warm friendship which existed between him
and our former Assistant-Secretary, Mr. Dallas, and the deep
interest which he took in the welfare of Mr. Dallas’s family.

Hueu Exton, M.D., was born at Huddersfield in January, 1833.
At first he was apprenticed to a medical man there, but afterwards
studied in London, and then at Leyden and Giessen. He went to the
Cape of Good Hope in the ‘fifties,’ settling in practice at Cape Town;

Vol. 60. ] ANNIVERSARY ADDRESS. lxxix

there he married his first wife in 1861. He then established
himself at Grahamstown, and about 1870 made a long trip north-
- ward in what is now Rhodesia, and there he gratified his taste for
natural history ; while shooting big game he had narrow escapes
from danger, being cool and tactful. On his return he decided to
settle at Bloemfontein. Here he had an extensive practice, and
was highly respected by Boer and European alike. During his
long stay at Bloemfontein he was a member of the Town Council,
and was elected Burgomaster (Mayor) two years in succession.
He was, moreovér, the founder of the Museum there, and was its
active Curator for some years. He came to England in 1883, with
same of his family, and especially enjoyed the advantages of his stay
in London. On his return to South Africa he took up his residence
at Johannesburg, with a busy practice, becoming President of the
Medical, Natural History, and Geological (South Africa) Societies.
In 1883 he was elected a Fellow of the Geological Society of
London, and contributed a note and plan, with specimens, of the
gold-bearing rocks of the Witwatersrand.

On the outbreak of the War in 1899, Dr. Exton acted as Civil
Surgeon with the British troops. He was stationed in the Hospital
at Ladysmith from the time of its relief (1900) until a few months
before the Declaration of Peace (June, 1902); these few months
were spent in the military hospital at Harrismith, where he
suffered much from the very cold winter. He finally went to
King William’s Town (British Kaffraria), where he died suddenly
on January 7th, 1903.

Dr. Exton has left five sons, one of whom is in the medical
profession ; the others are interested in mining, enginecring, and
photography.

The Council of the South African Geological Society on
December 7th, 1902, received his resignation of the Presidency,
and gratefully acknowledged his services and help ever since the
formation of the Society in 1895. In the funeral-sermon at
St. Mary’s, Johannesburg, his friend the Rector said of him that
‘he spared neither time nor pains in doing good work.’

He was an enthusiastic Freemason (pastmaster) and an ardent
geologist. The results of his researches at Ladysmith he con-
tributed to the ‘ Geological Magazine’ in 1891, in his Notes on the
Neighbourhood of Ladysmith, in Northern Natal : (1) with reference
to the local intrusive igneous rocks (chiefly andesite-diabase) ; and
(2) on some travelled blocks, with peculiar structure, in the Ecca

lxxx PROCEEDINGS OF THE GEOLOGICAL SOCIETY. May 1904,

Shales of the district. Lastly, at Harrismith he devoted much time
to collecting specimens from and comparing the strata of the neigh-
bouring hills ; but his notes have not been published.'

Watrer Drawsriver Crick was born at Hanslope on December
15th, 1857. Beginning life as a clerk in the Goods Department
of the London & North-Western Railway Company, he afterwards
became a traveller for a firm of shoe-manufacturers in Northampton
—an occupation which brought him into intimate acquaintance
with much of the North of England, and of Scotland and Ireland.
At last, in 1880, while still a young man, he started in business
with two partners as a firm of boot-and-shoe manufacturers in the
same town, and continued to increase in prosperity until, in the
end, the enlarged business passed entirely into his own hands.
Karly in life he had attended classes in chemistry and geology, and
became an enthusiastic field-naturalist and collector of fossils.
As his worldly means increased, he added other subjects of interest
to his collecting-list—such as first editions of standard English
literature, choice bindings, book-plates, coloured prints, stamps,
coins, English porcelain and furniture. But geology and conchology
continued to be hisfavourite recreations. He succeeded in gathering
together a valuable collection of specimens, and gave particular
attention to fossil gasteropoda and foraminifera. He took much
interest in the local institutions of Northampton, especially the
Natural History Society and the Free Library. He joined the
Geologists’ Association in 1886, and was elected into our Society
in 1892. For the last four years he had been aware that his
tenure of life was feeble; and at last, after only a few days’ illness,
he succumbed to syncope resulting from an attack of angina
pectoris, on December 28rd, 1903, in the 47th year of his age.

CONTINENTAL ELEVATION AND SUBSIDENCE.

As it is customary at this Anniversary that the occupant of the
Presidential Chair should offer to the Society some observations on
the progress of Geology during the preceding year, or on some
special department of the science which seems to him worthy of

' This notice of Dr. Exton has been written by Prof, T. Rupert Jones,
F-.R.S.

Vol. 60. | ANNIVERSARY ADDRESS. Ixxxl

attention, I have been unwilling that this time-honoured usage
should be wholly omitted from our programme to-day. No one
can more keenly regret than I do the enforced absence of our
President, and the consequent loss of the brilliant and suggestive
essay with which, had his health permitted, he would doubtless
have favoured us. I will not pretend to undertake to fill the gap
thus occasioned. All that I can attempt is to ask your attention
for a little to an old and familiar problem which has, during recent
years, once more come prominently forward in the copious litera-
ture of our science. I refer to the question of Changes in the
relative Levels of Sea and Land, and I propose to offer a
short summary of the present condition of the evidence which the
British Islands afford for the discussion of this subject.

You are well aware that, among the later events in the geological
history of Western Europe, few haye attracted more notice or have
given rise to more prolonged discussion than those which imply
changes in the relative positions of sea and land. Without entering
into the history of the controversy which began on this subject in
the middle of the eighteenth century, I may remind you that
Celsius in 1743 maintained that the proofs of apparent rise of land
in Sweden were to be explained by a measurable sinking of the
surface of the sea. This view was supported by Linneus, but did
not meet with universal acceptance, some observers holding that it
was the land which was rising. An important contribution to the
discussion was made in 1802 by Playfair, in his immortal ‘ Illus-
trations of the Huttonian Theory.” He conceived that
‘in order to depress or elevate the absolute level of the sea, by a given quantity,

in any one place, we must depress or elevate it by the same quantity over the
whole surface of the earth.’ (Op. czt. § 392, p. 446.)

He held that, although there is reason to believe that changes in the
solid ocean-floor do take place, which may affect the level of the
surface of the water, yet that such changes probably are compara-
tively slow and imperceptible. He concluded, therefore, that

‘the simplest hypothesis for explaining those changes of level, is, that they pro-
ceed from the motion, upwards or downwards, of the land itself, and not from
that of the sea.’ (Op. cit. § 393, p. 447.)

This deduction was generally accepted by geologists during the
greater part of last century, although it was disputed by a few
writers who maintained that, from various causes, the level of the
-sea must be subject to considerable change.

IXxxli PROCEEDINGS OF THE GEOLOGICAL society. | May 1904,

Further consideration of the subject has shown that, while
Playfair’s conclusion may be accepted as a true explanation of local
changes of relative level, yet that alterations of sea-level, wide in
their geographical extent and serious in their vertical amount, may
be brought about by movements of the hydrosphere, and without
any movement, upward or downward, of the land. It is now
recognized, for example, that the attraction of masses of high land
must seriously raise the level of the adjacent seas, and that a
similar effect will follow from the accumulation of a massive ice-
cap at either pole. There can be little doubt, also, that during the
secular cooling and contraction of the planet, the floor of the ocean-
basins is progressively sinking, and that the consequence of this
subsidence must be a proportionate emergence of land. But we
are profoundly ignorant of the rate at which such subsidence takes
place. Probably it is, on the whole, exceedingly slow, although it
may be varied by occasional collapses, which, when they take place,
doubtless give rise to gigantic seismic waves.

The objections which Robert Chambers and others made to the
acceptance of Playfair’s doctrine of the practical invariability of
the sea-level have been augmented by various writers in more
recent years, and most notably by my distinguished friend Prof.
Suess. After a detailed investigation of the evidence adduced in
favour of the elevation and subsidence of land, the great Austrian
geologist has come to the conclusion that this evidence has been
misinterpreted, that there are no vertical movements of the litho-
sphere (except such as may be connected with the secular contrac-
tion of the planet, as in the formation of mountain-chains), and that
the doctrine of the slow uprise and sinking of countries is a mere
phantasy, like the old ‘ Erhebungstheorie,’ of which he regards it as
a relic. This view he has interwoven in the magnificent and im-
pressive picture which he has drawn of the grand march of the
evolution of the earth’s surface-features. Let me not be thought
to be wanting in admiration of his great ‘ Antlitz der Erde, if I
venture to express my dissent from this particular doctrine, which
is there expressed with all the fullness of knowledge and literary
skill of which its author is so consummate a master.

Prof. Suess’s opinions as to the secular elevation and depression
of land have not escaped opposition and criticism, especially
on the part of the geologists of those countries from which the
classic examples of terrestrial upheaval have been drawn. But
coming to us, as they do, from one gifted with such high powers

Vol. 60.] ANNIVERSARY ADDRESS. ]xxxill

of philosophic analysis, who has himself looked at some of
the evidence on the ground, and has diligently perused the litera-
ture of the subject, they deserve the most serious consideration.
It may serve some useful purpose, therefore, if we pass in brief
review the state of the evidence presented in our islands for the
discussion of this disputed problem.

No features in British geology are more familiar than the
abundant proofs which have been brought forward of comparatively-
recent changes of level, both in an upward and downward direction.
A somewhat complex series of oscillations has been recognized, re-
garding the true amount and sequence of which opinions are still
divided. Itis no part of my present purpose, however, to review
the whole length and breadth of this complicated piece of geological
history. I will not enter upon the consideration of the sequence
of the successive oscillations of which the records remain more or
less clearly preserved. For the discussion which I propose it will
be sufficient to consider the character of the evidence that will best
furnish answers to the two questions: lst. What reliable proofs
can be adduced of Pleistocene and post-Pleistocene changes in the
relative levels of land and sea? ; and, 2ndly. How far do these proofs
carry us in the endeavour to ascertain whether the changes have
resulted from oscillation of the sea-level, or from movements of the
solid land ?

In all such discussions it is difficult to avoid the use of a long-
established terminology, which has been generally accepted as cor-
rectly expressive of the facts to which it is applied. We have been
accustomed to speak of the movements as inherent in the land rather
than in the sea. But it may be desirable, in our examination of the
facts, to avoid the use of such terms as Elevation or Upheaval, and
Depression or Subsidence, as too obviously begging the question
to be answered. Instead of using these phrases I will speak of the
Emergence and Submergence of Land, the former being the
negative and the latter the positive movements of Prof. Suess’s
nomenclature.

I. EvIpENcE FoR THE EMERGENCE AND SUBMERGENCE OF LAND.
(i) Emergence.

Various kinds of evidence have long been cited by geologists,
in proof that what is now dry land has once been under the sea.
The favourite demonstration has been based on the presence of

|xxxlv PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

marine organisms upon terra firma; and this argument must be
admitted to be in most cases sound. But it is now recognized
that the mere occurrence of these organisms may not be itself
a proof of former submergence, for they may by various means
be transported to the land, without necessarily implying any
change of level. We know, for example, that by a body of ice,
moving out of a sea-basin upon the land, the shells of a sea-floor
may be scraped up and carried above sea-level. Up to what
heights this kind of transport is possible, or probable, we cannot
at present say. But that it is a vera causa seems to be put beyond
question by the broken condition of the shells, the mixture of species
belonging to very different depths, and the manner in which they
are dispersed through the various kinds of Drift in which they lie.

To keep the discussion within due bounds, I shall limit my
remarks to the evidence of emergence supplied by what we call
Raised Beaches. Geologists in the British Isles have long indulged
the confident belief that these beaches afford demonstrative proof
of changes in the relative levels of sea and land. The abundant
and striking examples of them around our coasts have been
universally accepted among us as marking former sea-margins,
whether the sea be supposed to have risen upon the land or the
land to have been upheaved above the sea. The recurrence of
precisely-similar terraces along the western coast of Norway, but
on a still more impressive scale, has been regarded as furnishing
evidence of an extensive emergence of land, from the south of
Britain to the northern end of the Scandinavian peninsula.
Prof. Suess, however, seeks to show that, at least as regards
the north-western coast of Norway, these opinions are based upon
a misreading of the evidence. After his visit to that region, and
his study of the literature of the strand-lines there so wonderfully
developed, he has come to the conclusion that the Norwegian fjords
furnish no argument against his doctrine that there has been no
recent upheaval of the land. He asserts that
‘we must interpret all the seter [rock-shelves] and the great majority of the
terraces in the fiords of Western Norway as proofs of the retreat of the ice that
once covered so much of the peninsula, and not as proofs of any oscillations of
the surface of the sea, still less of any movement of the solid land.’ '

It would widen the enquiry too much to enter upon an exami-
nation of the evidence, as it is presented in Scandinavia. But,
having myself been all my life familiar with the strand-lines of this

1 ¢Das Antlitz der Erde’ vol. ii (1888) p. 457.

Vol. 60. | ANNIVERSARY ADDRESS. Ixxxv

country, and having traced those of the Norwegian coast from
Bergen to Hammerfest, I may perhaps be permitted to point out,
as deferentially as I possibly can, one or two of the insuper-
able difficulties with which, as I venture to think, Prof. Suess’s
theoretical explanation is beset. He has, as it scems to me,
unwittingly confounded two sets of beach-lines, which differ a good
deal from each other in general character, and are entirely distinct
in origin, Availing himself of the remarkably full and interesting
researches of Scandinavian geologists regarding the glaciation of
their country, he dwells upon the importance of the terraces left
by the freshwater lakes that were dammed back by the great
ice-sheet as it retired. He believes that these phenomena extended
even to the Norwegian coast, and that the strand-lines of the
fjords, whether in the form of platforms eroded out of the solid
rock (seter) or terraces of sediment, mark former levels of lakes
that filled these valleys when their mouths were blocked up
with the ice-sheet. As the lowest of these strand-lines includes
sands and gravels crowded with marine shells, he is compelled
to admit that it marks a former sea-beach. But he endeavours to
discriminate between it and the other horizontal shelves, which
follow it in parallel lines at higher levels. He affirms that the
latter present a series of ‘ characters absolutely irreconcilable with
what we know of the action of the sea along a shore’—such as the
series of fragmentary terraces found at increasing heights inland,
their absence from the parts near the general coast-line, and the
breadth of the seter. He passes lightly over the fact that some
of these higher terraces have yielded marine organisms which are
progressively of more Arctic character, according to their altitude,
and according, consequently, to the antiquity of the sediments in
which they lie.

Now, according to the experience of those northern geologists
who have specially studied Scandinavian glaciation, the lakes that
were formed by the ponding-back of the drainage against the flanks
of the ice-sheet lie to the east of the watershed of the peninsula.
These observers have ascertained that when this ice-sheet was
waning, it retreated eastward from the backbone of the country
and lay on the eastern or Swedish slope, leaving a gradually-
increasing breadth of ground clear of ice, The streams flowing
eastward over this liberated area had their drainage arrested
against the margin of the ice; and hence arose a vast series of
lakes which lasted for longer or shorter periods, until, by the

Ixxxvl PROCEEDINGS OF THE GEOLOGICAL society. — | May 1904,

continued creeping-backward of the ice, their contents were
drained off to lower levels. A multitude of records of old water-
levels or ‘strand-lines’ was thus left over the surtace of the
country. It is the opinion of Scandinavian geologists that all
the terraces not of marine origin lie within that area.’

As one of the distinctive characters of the shore-lines left by the
elacier-lakes, the author of the ‘ Antlitz der Erde’ cites the occur-
rence of the rock-shelves or platforms (seter) eroded out of the
solid rock, and he refers the origin of these common features of the
fjords to the daily oscillations of temperature at the surface of the
lakes.* I shall try to show, by a reference to the abundant examples
of such rock-shelves in our own islands, that this explanation is
at least inadequate. If, however, for a moment, we grant that the
strand-lines, including the seter of the Norwegian fjords, do mark
levels of former freshwater lakes, it is obvious that, in order to
pond the drainage back and produce these lakes, the mouths of
the fjords must have been in some way blocked up by a barrier
which has disappeared. If this barrier were land-ice, as Prof.
Suess appears to assume, the water would rise behind it, until,
if the overflow found no escape into the Atlantic, it would pass
over the watershed, and joining the various bodies of water that
were there intercepted by the great Swedish ice-sheet, would
eventually find its way into the Gulf of Bothnia. There would
thus be two huge bodies of ice, between which the drainage was
accumulated.2 We must remember, however, that the strand-lines
are not confined to the fjords, but sweep round the coast on either

1 See two important papers by A. M. Hansen in the Christiania ‘ Archiv for
Mathematik og Naturvidenskaberne.’ The first of these, vol. x (1886) pp. 329-52,
deals with the occurrence of seter or strand-lines in connection with ice-
dammed lakes at great heights above the sea, ranging from 652 to 1090 metres.
The second, vol. xiv (1890) pp. 254-343, & vol. xv (1892) pp. 1-96, contains a
full discussion of the character, distribution, and origin of the strand-lines of
Norway. See also G. de Geer, Sveriges Geol. Undersokn. Ser. C, No. 161, 1896;
& G. Andersson, 2bid. No. 166, 1897, p. 5. Although the largest and most
abundant lakes, formed during the retreat of the ice-sheet, undoubtedly lie on
the eastern or Swedish side of the watershed, it is not improbable that others
were produced also on the western side by the irregular way in which the ice
disappeared. Dr. C. Sandler has suggested that the mouths of the Norwegian
fjords may have been blocked up by a succession of vast moraines, which kept
back the sea and turned these sea-lochs into inland lakes. But the difficulties in
the way of the acceptance of this explanation are insuperable. See Petermann’s
Mittheil. vol. xxxvi (1890) pp. 209, 235.

2 «Das Antlitz der Erde’ vol. ii (1888) p. 481.

* Dr. Sandler, in the paper already quoted, has considered the possibility
of such a flanking ice-dam, but has dismissed the idea as untenable.

Vol. 60. | ANNIVERSARY ADDRESS. Ixxxvit

side, and even appear on the islands that flank the mainland of
Norway, some of them actually looking out to the open sea. The
supposed ice-sheet must therefore have lain mainly outside these
islands. But there is absolutely no evidence of any such detached
western ice-body, and every reason to believe that it never existed.

At the period of maximum glaciation the ice-sheet probably
advanced westward beyond the present limits of the land. But,
when it began to retreat, it would naturally creep backward up the
fjords, which would be still the main lines of ice-drainage. We
can conceive, indeed, that at an early stage of this retreat, a glacier
or ice-lobe may here and there have blocked up a large valley and
produced a lake, as in the instances cited by Prof. Suess from
Greenland. But the strand-lines of Western Norway are not
exceptional phenomena. They continue as characteristic features
of the coast-line and of the fjords for several hundred miles, and
must owe their origin to some general and widely-extending cause.
That they are true sea-beaches, as has been generally believed, I
have not the smallest doubt.

Fortunately, we possess in our own islands a body of evidence
bearing on this question, not certainly as voluminous and im-
pressive as that of Scandinavia, but having the compensating
advantage. of great simplicity and clearness. On the one hand, the
famous Parallel Roads of Glen Spean and Glen Roy, and those of
other less-known valleys, stand out as acknowledged relies of glacier-
lakes ; while round our coasts, on both sides of the country, raised
beaches, which have been hitherto regarded as old sea-margins, run
for hundreds of miles. These two series of terraces are found close
together, yet there is, I think, no difficulty in drawing a satisfactory
distinction between them. Indeed, their proximity enables us all
the more clearly to perceive their contrasts. :

There must, of course, be certain general resemblances between
the littoral formations of lakes and of the sea.‘ The erosion
produced by the waves or wavelets of a body of fresh water is
similar in kind to that performed by the sea, although different in
degree. Im like manner, the beaches of deposit formed in lakes
possess, on a minor scale, many of the characters of those accumu-
lated along the sea-shore. And it may readily be granted that, in
isolated exposures of some old beach, it may be difficult or im-
possible to decide, in default of evidence from elsewhere, whether

1 This subject las been instructively treated by Prof. G. K. Gilbert in his
monograph on Lake Bonneville, U.S. Geol. Sury. Monogr. no. i, 1890.

]xxxvil PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

the phenomena observable are to be assigned to the work of the sea
or of a lake. Nevertheless, on a review of the whole evidence, at
least as it is presented in this country, I feel very confident that
there is no risk of confusion in this matter. The marine terraces
maintain their distinctive features up to the very foot of the slopes
where the lake-terraces begin, while these in turn are marked
by other special peculiarities.

Let any observer who has followed the great 50-foot raised beach
along the western coast of Scotland and up the Linnhe Loch to
the mouth of the Great Glen, look away to the right hand where
the wide Strath of Spean leads into the interior. While yet
standing on the platform of the raised beach, if the air be clear his
eye may detect the beginning of a line, drawn as with a ruler, at
the same height along the slopes on either side of the valley. This
is the lowest of the three great Parallel Roads of Glen Roy, and
runs at a height of 850 feet above the level of the sea. If he will
now ascend into Glen Roy, where the three terraces are best seen,
he will soon be struck by the distinctive differences between these
old lake-margins and the raised beaches with which he has already
made himself familiar. In the first place, he will remark their
faintness, as compared with the marine platforms of the coast.
Though readily traceable from a distance in their horizontal con-
tinuity, they are in many places hardly discernible when one is
actually standing upon them. A little examination soon reveals that
each of them has been produced mainly by the arrest of sediment
washed from the slopes above into the water of the vanished lake.
Tnstructive illustrations of this process may often be observed along
the sides of reservoirs which have been constructed in steep-sided
valleys: there each prolonged halt of the water at a particular level
is marked by a shelf of detritus which, blown by wind and washed
down the declivities by rain. is stopped when it enters the water,
where it accumulates as a miniature beach.

Here and there, especially on more exposed projections of the
hillsides, there has been a little cutting-back by the shore-waves
or drifting ice-floes of the old lake in Glen Roy. Occasionally also,
where a streamlet has entered the water, its arrested detritus has
accumulated as a broad, flat delta or terrace. But it is manifest
that, in such limited expanses of water, wind-waves could have had
comparatively little erosive power. Nor can we imagine that, even
if the water froze, its floe-ice could have had any potent influence
in sawing into the rocks of the declivities and producing seter or

Vol. 60. ] ANNIVERSARY ADDRESS. Ixxxix

rock-shelves. Certainly throughout this wonderful assemblage of
lake-shores, there is nothing for a moment to be compared to the
incised platforms of rock so abundant as part of the raised beaches
of the western coast of Scotland. We must remember aiso that the
production of such ice-dammed lakes took place as a mere episode in
the retreat of the ice. No means are available to determine what
may have been the length of time during which the water stood at
the level of any one of these Parallel Roads. We may probably
infer, from the absence of well-marked and continuous intervening
shore-lines, that the shrinkage of the ice and the consequent lowering
of the level of the water were somewhat rapid.

The Parallel Roads of Lochaber, although the most imposing,
are not the only examples of the shore-lines of ancient glacier-
lakes in this country. Another striking case is that of Strath Bran
in Ross-shire, where the glaciers descending from the mountains
on each side ponded back the drainage of the valley, and sent it
across the present watershed of the country at a height of about
600 feet above the sea. The conspicuous gravel-terraces at Achna-
shean are a memorial of this vanished sheet of water.’

Now, with these undoubted records of ancient lakes, let us com-
pare the structure and distribution of our Raised Beaches. These
shore-lines are found, on both sides of Scotland, at approximately
the same heights above the level of the sea. They are partly
terraces of deposit, and partly true seter or platforms cut out of the
solid rock, the same beach presenting frequent alternations of both
structures. In general, it may be said that the detrital terraces
are found chiefly in bays, sea-lochs, or other sheltered places ; while
the rock-terraces are conspicuous in more open sounds and exposed
parts of the coast, where the tidal currents and wind-wayes are most
powerful.

As the highest terraces are the oldest, they have been longest
exposed to the influences of denudation, and are thus the faintest
and most fragmentary. But the dimensions and perfection of a
raised beach do not depend merely on age, but in large measure on
the length of time that the water stood at that level, and the varying
local conditions that favoured or retarded the planing-down of solid
rock or the deposition of littoral sediment.

That these beaches unquestionably mark shore-lines of the sea
may be inferred on three grounds :—(1) Their position on both
1 ‘Summary of Progress of the Geological Survey for 1898’ pp. 175, 176.

VOL. LX. g

xe PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1904,

sides of the island at corresponding heights. No possible arrange-
ment of ice-dams in the Atlantic and in the basin of the North Sea
ean be conceived that would have everywhere ponded back the
land-drainage to similar levels. (2) Their independence of local
conditions. The same terrace may be traced down both sides of
a sea-loch and round the coast into the next loch, retaining all
the while its horizontal continuity. Not only on the mainland,
but on the chain of islands outside, the same parallel bar has
been incised, both on the inner or sheltered side and also on the
outer flank looking to the open Atlantic. (3) Their organic
remains. From the youngest of the beaches up to the highest, the
terraces of deposit contain marine organisms which have not been
scooped out of some earlier formation, but lie in the positions in
which the animals died, or into which they were washed by shore-
waves and currents. The fossils of the latest beaches are entirely
identical, or almost so, with forms still living in the adjacent seas,
while those of the higher beaches are boreal or Arctic.

In some sheltered places, such as the Dornoch Firth, especially
near Tain, and some inlets on the west side of the island of Jura,
a number of successive bars or terraces of deposit may be observed,
up to heights of 100 feet or-more above the sea. But there are
in Scotland three strand-lines so conspicuous and so persistent that
attention may be confined to them. From what has been taken
to be their average height above mean sea-level or Ordnance-datum,
they are known respectively as the 100-foot, the 50-foot, and the
25-foot beaches.

Here I should like to point out what I have long regarded as a
reproach to the geologists of this country. No systematic effort
has ever yet been made-to determine accurately, by a series of
careful levellings, the precise heights of these old shore-lines. We
only know that, roughly speaking, a raised beach retains its level
for long distances, and appears to lie at the same height on both
sides of the country. But we are still ignorant whether or not an
appreciable difference of level might not be detected between the
western and the eastern development of the same beach, nor do we
know whether it would not betray some variation in its height
between its northern and southern limits. There seems to be a
tendency for the levels of the beaches to rise slightly towards the
head of an estuary or sea-loch. But whether this difference is more
than can be accounted for by the ordinary elevation of the tidal
wave as it ascends a narrowing inlet, remains to be determined.

Vol. 60. | ANNIVERSARY ADDRESS. x¢l

Obviously, until accurate information is obtained on all ascertain-
able differences of Jevel in the system of our raised beaches, we
must remain unprovided with some of the most important material
for a discussion of the history of these beaches. It is surely not
too much to hope that one or more observers, endowed with the
requisite geological knowledge and geodetic skill, may before long
be found who will undertake the investigation of this interesting
subject, and thus aid in the sojiution of a problem which does not
merely concern the evolution of our own islands, but is of high
importance as a question in geological theory.

The 100-foot terrace carries us back into the Glacial Period.
Bones of Arctic species of seals have been obtained from its deposits,
and its fine clays and sands point to the settling-down of glacier-
mud in sheltered firths. Here and there, especially where it has
accumulated in front of a glacier that bore down coarse detritus, it
is marked by a thick terrace of unfossiliferous gravel and sand, as
in the remarkable green platforms which form so conspicuous a
feature on either side of the narrows of Loch Carron. Its absence
from the upper part of this and other sea-lochs has been accounted
for, on the supposition that these fjords continued to be filled with
ice which barred hack the sea and broke off there in icebergs. The
deeper-water deposits of the period of this beach are probably
represented by the Clyde Beds and their equivalents, with their
abundant and well-preserved boreal and Arctic shells.

The 50-foot beach is much more perfect than the last-named. It
must mark a prolonged halt of the land at that particular level.
It is in some places a terrace of deposit, in others a platform (or
sete) levelled out of the rock. This strand-line also belongs to the
Glacial Period. After it was formed, some of the glaciers of Ross-
shire and Sutherland came down to the edge of the sea, and shed
their moraines upon the terrace.’ Its organisms are stiil somewhat
Arctic in facies.

The 25-foot beach is remarkably perfect in some firths, such as
those of the Clyde and Forth, as well as along many parts of the
eastern and western coasts, and it extends into the North-West of
England and the North-East of Ireland. It combines both terraces
of deposit with rock-platforms or seter, and its abundant fossils
are still common: in the neighbouring sea. Though it sometimes
presents a striking feature in the topography, it probably marks a

* L. W. Hinxman, Trans. Edin. Geol. Soc. vol. vi (1892) p. 249.
g2

xcil PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

less prolonged interval of rest than the 50-foot beach. Itis not only
post-Glacial, but in some places contains traces of Neolithic man.

In the structure of these old sea-margins a feature of special
interest is presented by the platforms which have been eroded out of
the solid rock, and which afford not a little light as to the origin
of the Norwegian seter. On the east side of Scotland these plat-
forms have been to a great extent cut in Boulder-Clay-——a material
that would offer comparatively feeble resistance to erosion. On the
western coast, however, the rock-platforms, both of the 50-foot and
the 25-foot beaches, have been in large measure cut out of much
more enduring materials. The rock-shelves of the east side of Jura
have been levelled in hard schists and quartzites ; those so con-
spicuous around the island of Lismore in the Linnhe Loch, out of
massive pre-Cambrian limestone. In Mull and the other members
of the Inner Hebrides, they have been eroded in various rocks of
the Tertiary volcanic series. In the Firth of Clyde, they have
been planed down among the sandstones and igneous rocks of the
Carboniferous and Triassic formations, as well as here and there in
Boulder-Clay.

The surface of these rock-terraces is flat, and usually covered with
a thin coating of grass-grown soil through which harder knobs and
stacks of the underlying rock here and there protrude. At the
inner margin of the terrace, the rocks rise into a cliff or steep bank,
the base of which is frequently pierced with caves. That these
caves were mainly due to erosion by moving water is abundantly
evident in the rounded and smoothed surfaces of their sides. Their
floors are often rough with round shingle, which has undoubtedly
been the material employed by Nature in their excavation. No one
who has made himself familiar with the rock-platforms which at
the present day are in course of erosion by the sea along these same
coasts, can for a moment doubt that the rock-plattorms of the raised
beaches which, down to the minutest point, resemble them, have
likewise been eroded by the waves of the sea. Nowhere have I
seen this lesson more instructively taught than at Kinecraig Hill on
the coast of Fife, an old voleanic vent which, from a height of
200 feet above the sea, descends in vertical precipices to the edge
of the present beach. Round the west side of the hill the three
terraces (100-foot, 50-foot, and 25-foot) have been cut out of the
volcanic agglomerate as parallel shelves or seter. At the foot of
the cliffs when the*tide is out, one can walk for half a mile upon
a broad flat platform, which is now in course of erosion out of the

Vol. 60. | ANNIVERSARY ADDRESS, x¢ciil

same material by the flux and reflux of the tides in the open
estuary of the Forth. Were the land to emerge above its present
level, a fourth platform would be exposed along this coast, broader
and more perfect than its older predecessors above, but showing all
the same family characteristics.

That the daily oscillations of temperature invoked by Prof.
Suess in explanation of the Norwegian seter have had their share
in the erosion of these Scottish examples, cannot be doubted. But
this share is evidently feeble in amount now, although it may have
been more considerable during the Glacial Period. More potent as
a contributory influence in the erosion of the older terraces, was
probably the action of floating ice, driven along the shores by winds
and tidal currents. Down to the time of the 50-foot beach, when
glaciers in the North of Scotland descended to the edge of the sea,
there may have been a good deal of such ice in the more enclosed
sea-lochs, where the water, freshened by the discharge of melting
snow-fields and glaciers, might itself be covered with a cake of ice.
And there was not improbably a good deal more ice in the fjords of
Norway. The grinding and rasping action of such ice, driven by
gales ashore, has long been remarked. JBut, in any case, we are
justified in regarding the Scottish seter as examples of truly marine
erusion, and I can see no reason why those of Norway should not
have had the same origin. It is at least clear that the statement
that the characters of seter ‘are absolutely irreconcilable with
what we know of the action of the sea near its surface, cannot be
sustained.*

Certain features of the extension of the raised beaches throughout
Britain appear to be of fundamental importance in relation to the
discussion of the problem of the emergence of land. Though so
persistent along both the western and eastern coasts of Scotland,
these beaches, as is now well known, do not stretch northward into
the Orkney and Shetland Isles. Along precipitous sea-fronts we
could not expect to meet with them, but among these islands there
are endless sheltered inlets and bays which, had they indented the

‘ As far back as 1874 8. A. Sexe expressed the opinion that the sea does not now
incise any strand-lines like the old seter (Universitetsprogram, Christiania,
1874, p. 38). Eight years previously, after a visit to the Norwegian seter, I was
eonvineed of their marine origin, and suggested that their erosion ‘may have
been due in large measure to the effects of the freezings and thawings along the
old,ice-foot, and to the rasping and grating of coast-ice. Such, too, may have
been the origin of the higher horizontal rock-terraces of Scotland’ Proc, Roy,
Soe. Edin. vol. v (1866) p. 548.

KCL PROCEEDINGS OF THE GEOLOGICAL society. [May 1904,

shores of the mainland of Scotland, would undoubtedly have had
their fringe of terraces. The conditions for the development and
preservation of the beaches were so entirely favourable, that their
absence can only be legitimately accounted for on the supposition
that they can never have existed here. Still farther north, among
the Ferde Isles, no trace of any raised beaches is to be found among
the numerous natural harbours and creeks that break the monotony
of the vast ranges of basalt-precipice. Here, again, we cannot
suppose that any such beaches were ever formed.

If, now, we turn to the southward extension of the Scottish
raised beaches, we find these features beginning to lose their
distinctness as they are traced into England. The 100-foot beach,
which has not. been recognized along the northern coast of Sutherland
or in Caithness, appears also to fail before it reaches the English
coast. It is well-marked in the estuaries of the Clyde and Forth,
whence in a fragmentary condition it has been traced into Wigton-
shire on the one side, and to the north of Berwickshire on the other.
But no remnants of it appear to have been detected in the North of
England.

It is much to be wished that a series of detailed investigations,
similar to those desiderated for Scotland, should be undertaken for
the far fainter and more fragmentary raised beaches of England
and Wales. At present no one has attempted to correlate these
shore-lines in the two kingdoms. South of the Tweed the evidence
is confessedly imperfect, but although a passing observer may be
struck by the absence of the terraces which are so distinctive a
feature in Scotland, a more sedulous search might yet detect them
in places where they have not hitherto been recognized.

A raised beach standing at a maximum height of ebout 40 feet
above high-water mark has almost entirely disappeared from the
eastern coast of England, the only surviving portions being apparently
that at Saltburn, and perhaps that at Hunstanton.’ The presence
of Glacial Drift above the raised beach of East Yorkshire would seem
to place that old shore-line back in the Glacial Period. It may
possibly be cozeval with the 50-foot beach of Scotland, perhaps even
older. On the opposite side of the island a raised beach at St. Bees
stands between 20 and 30 feet above the sea. It might be surmised
to be of post-Glacial age, and to belong to the same interval as that
which is marked by the 25-foot beach of Scotland and the North-

1 ©, Reid, ‘Geology of Holderness’ Mem. Geol. Surv. (1885) p. 72.

Vol. 60.] ANNIVERSARY ADDRESS. XCV

East of Ireland. But if Mr. Holmes’s suggestion be well-founded,
this beach may really represent the 50-foot terrace. He is of opinion
that the adjacent sunk forest indicates a later submergence, whereby
the beach has been brought into its present relative position.’

In England and Wales the most continuous and best-preserved
examples of raised beaches are to be seen on the coasts of the
southern counties. Mr. Clement Reid has traced one of these
shore-lines through West Sussex and Hampshire into Dorset, at a
height of about 130 feet (or rather more) above the mean sea-level.
This terrace is best developed at Goodwood Park, where its sandy
layers have yielded numerous foraminifera, together with Balanus,
Mytilus edulis, Tellina balthica, Trophon, and a Pholas-bored
boulder of chalk weighing about 2 hundredweight. ‘This raised
beach is overlain by 17 feet of Coombe Rock, which, as Mr. Reid
has shown, points to Arctic conditions of deposit, and thus throws
the terrace back into the Glacial Period. The same observer has
noted in many places along the southern coast a succession of shingle-
terraces which may mark stages in the emergence of the land.*

The lower raised beaches along the coasts of Dorset, Devon, and
Cornwall have long been known, although their geological age, their
history, and their relation to the later phases of Pleistocene time,
have not yet been satisfactorily cleared up. William Pengelly, who
devoted so much time to this subject, clearly proved that these
beaches do not stand now at their original level, but that after their
formation the region was upraised to the amount, as estimated
by him, of not less than 70 feet, when the lowest sunk forests
flourished as land-surfaces, and that thereafter came a submergence
of certainly 40 and perhaps many more feet.*

Mr. Tiddeman has shown that, in Gower, on the coast of
Glamorgan, a raised beach which lies from 10 to 30 feet above
the level of the modern beach, and contains littoral shells of common
species, is yet older than at least some part of the Glacial Period,
for it is overlain by Glacial Drift. In this case also, its present
is probably not its original level. There is evidence of considerable
submergence, at a comparatively-late period, farther east in the same

* Trans. Cumberland Assoe. pt. ii (1876-77) p. 70. ‘
2 «Geology of the Country near Chichester’ Mem. Geol. Surv. (1903) p. 40;
Geology of the Country around Ringwood’ 7bid. (1902) chapt. ix; & Quart.
Journ. Geol. Soc. vol. xlvili (1892) p. 544.
* Trans. Devon. Assoc. vol. i (1865) pt. iv, p. 34, & vol. ii (1867) pp. 25, 134.

X¢V1 PROCEEDINGS OF THE GEOLOGICAL socrETy. { May 1904,

county and along the southern coast of England, as will be more
specially remarked in a later part of this Address ; and the inter-
Glacial or pre-Glacial raised beaches of the whole of this region
doubtless stood at one time higher above the sea-level than they
do now.

The raised beaches of Ireland call for no special remark, beyond
an expression of regret that they are so few and so fragmentary.
The so-called ‘ 25-foot terrace’ of the Clyde Basin is prolonged into
the north-eastern counties of the sister-island, where it lies from
10 to 20 feet above the present sea-level, and has yielded so many
worked flints and flint-flakes that it is regarded as not older than
Neolithic. The same beach has been recognized at intervals on the
northern shores and also down the eastern coast, at least as far south
as Dublin Bay. But both along the east and west sides of the island,
the general absence of well-marked raised beaches in sheltered bays
and inlets, where, had they ever existed, they might have been
confidently expected to have been preserved, cannot but strike the
eye of the geologist. Recently Messrs. Muff & Wright, of the
Geological Survey, have detected an ancient shore-line at) Cork
Harbour which they have traced, not only within the Harbour, but
for a long distance on the shore to the east and west of that inlet.
Though only a few feet above the present high-water mark, this
beach has been ascertained to be older than the oldest Irish
Boulder-Clay, for it is overlain by the so-called ‘shelly marl’
which was brought in upon the land from the sea-basin. The
similarity of position and antiquity between this beach and that
underlying the Drift in Gower, is obviously as important as it is
interesting. A shore-line, which must be of pre-Glacial or inter-
Glacial age, is traceable in the South of Ireland and in South Wales.
It has not only survived the erosive processes of the Glacial Period,
but 1t appears to have outlived some serious alterations in the relative
levels of sea and land which have taken place since its formation.
Moreover, we have to note the fact that neither at Cork nor in Gower
does any younger post-Glacial terrace appear to be recognizable.
If we might judge from the analogy of other parts of these islands
where the succession of raised beaches is tolerably complete, we
should infer that if ever any later terrace existed here, it must now
be submerged—an inference which, it will be observed, is supported
by the evidence of considerable submergence in South Wales, and
on the southern coast of Hampshire.

Vol. 60. | ANNIVERSARY ADDRESS. xevil

(11) Submergence.

Of the various kinds of proof of the submersion of terrestrial
surfaces furnished in these islands, I will refer only to two: first,
the extension of land-valleys beneath the sea; and, secondly, the
existence of what are known as Sunk Forests.

1. That the fjords of Norway, the sea-lochs of the West of
Scotland, and the harbours or inlets of the West of Ireland were
originally valleys on the dry land, although now deeply submerged,
has long been an accepted belief among those geologists who have
specially considered the subject. The interval of time which has
elapsed since this submergence has not sufficed to fill up with
sediment these submarine depressions. By a study of the sea-
charts, we can still trace the winding curves of the ancient valleys,
and can even here and there detect among them the basins which,
when the present sea-bottom was a land-surface, were filled with
freshwater lakes. On the sea-floor to the east of our own country
and of Scandinavia, such relics of subaérial denudation are less
imposingly preserved, yet evidence of the submergence of land-
valleys has been noted there also. It must of course be re-
membered that the land on that side is of much lower altitude than
on the western coasts, that the ground slopes gently under the sea,
and that the valleys are comparatively insignificant depressions on
its general surface. Moreover, the more abundant drainage on the
longer slope east of the watershed, and the much greater develop-
ment of Drift on that side, leads to a far more copious discharge of
sediment into the shallow North Sea and the Gulf of Bothnia, and
the submarine prolongations of the old land-valleys are thus apt to
be buried under recent accumulations of detritus. There may,
however, perhaps be another cause for the contrast between the
profoundly indented and precipitous western coast and the com-
paratively low and monotonous trend of the eastern coast. J have
long been disposed to believe that the submergence has been greater
towards the west than towards the east. In the prolongation of
the West-Highland sea-lochs on the floor of the Atlantic outside,
the original land-surface sometimes lies 600 feet or more below the
present sea-level. The same fact presents itself in Norway, as in
the striking case of the sinuous submerged valley which continues
the line of the Stor Fjord, south of Molde, for some 50 kilometres
(or 31 English miles) seaward, and descends to a depth of 1000 feet
below the surface. If the submerged land-surface of North-Western

X¢eVlli PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1904,

Europe could be upraised some 600 feet, the submarine prolongations
of the sea-lochs would once more become glens and straths, and their
rock-basins would again be turned into freshwater lakes.

There is no similar series of well-marked submerged valleys on
the floor of the North Sea from which to estimate the amount of sub-
mergence of that tract, at least half of which, at no very distant date,
formed a land-surface that connected Britain with the rest of the
Continent. The charts show this sea-floor to consist of two distinct
portions. ‘he northern half forms a plain, which appears to slope
gradually towards the north. The southern half, however, rises
somewhat; rapidly from the edge of that plain into an escarpment that
runs in a north-easterly direction for a distance of 500 miles, from off
Flamborough Head to the Skagerrak. From the top of this escarp-
ment the surface undulates southward as a higher submarine plain,
traversed by the still feebly-traceable submerged valleys of the Elbe,
the Rhine, and the Thames, and covering an area of more than
50,000 square miles.’ An uprise of not more than 300 feet would
turn this tract into a rolling plateau of dry land, like the Downs
and Wolds of Yorkshire, which are its emerged continuation. Such
an amount of uplift would probably be amply sufficient for the
transaction of all the later geological history of the region. The
conversion of the area into a sea-bottom may not have been a
continuous process. It was probably in operation during the early
stages of the Glacial Period, and its latest phases come down at
least into Neolithic time.

2. The sheets of peat with stools and trunks of trees, known as
Sunk or Submerged Forests, and of such frequent occurrence
around the coasts of the British Isles, have long been confidently
regarded as proofs of recent subsidence of the land. That they
generally mark former land-surfaces cannot be doubted, for the
tree-stumps are seen to send their roots down into the soil under-
neath, and manifestly stand in the places where they originally
grew. The presence of hazel-nuts, elytra of beetles, land-snails,
and other terrestrial organisms, affords further confirmation of this
conclusion. The great majority of these vegetable accumulations
are found between tide-marks in bays and estuaries, and in many

1 See the excellent chart accompanying the paper by Mr. John Murray,
Proc. Inst. C. E. vol. xx (1861) p. 314. The submerged land-valleys off
the coasts of South Wales, Devon, and Cornwall have been described by Mr. T
Codrington, Quart. Journ. Geol. Soe. vol. liv (1898) p. 251.

Vol. 60. | ANNIVERSARY ADDRESS. XC1X

cases they can be seen to pass below the limits of the lowest tides,
and thus to be constantly in part submerged. The trees and the
freshwater plants must have lived above the reach of the sea,
so that they now lie 20 feet or more below the level at which
they originally grew; and the conclusion has been drawn that they
mark a general subsidence of these islands, to the amount of at least
20 feet, at a comparatively recent date.

I am inclined to believe that this conclusion has been rather too
sweepingly drawn. That some of the submerged forests may be
satisfactorily accounted for without any change in the level of the
land or of the sea, was urgently enforced more than eighty years ago
by John Fleming, in reference to the examples first brought to notice
by him in the estuaries of the Tay and the Forth.’ It will be
readily understood that, in the later stages of the Glacial Period,
when much detritus was swept off the land into the sea, the
conditions would probably be especially favourable for the formation
of alluvial bars along our coasts, such as are now in course of
accumulation for hundreds of miles on the southern coast of Iceland,
where some of the features of that period may still be said to
linger. Behind these barriers lagoons would be formed, which in
course of time might become marshes, and eventually peaty flats,
supporting a growth of trees. But when the supply of sediment
failed, and the sea, instead of heaping up the bars, began to breach
them, the level of the bogs would sink by the escape of their water
to the beach, and the tide at high-water would overflow and kill off
the forests. Occasionally, owing to the action of underground
drainage, the seaward margins of forest-covered peaty flats may
have been detached from the main body and launched downward on
the beach, even beneath low-water mark.

Prof. Suess invokes changes of this nature to account for the

phenomena of the sunk forests around the borders of the North Sea,
which he thinks do not indicate any change of level of the land.
He believes these changes to be of local origin, due sometimes to
downward slipping of the peat-mosses, sometimes to invasion of the
sea during violent storms, or where natural or artificial barriers
have been broken down, sometimes, as in the Baltic, to variations
of sea-level due to meteorological causes.
* 1 His account of the submerged forest on the south side of the Firth of Tay
is contained in-the 9th volume (1822) of the Trans. Roy. Soc. Edin., p. 419 ;
and that of the similar accumulation in Largo Bay, on the northern shore
of the Firth of Forth, in the Quarterly Journal of Science, Literature, & Art,
n. s. vol. vii (1830) p. 21.

Cc PROCEEDINGS OF THE GEOLOGICAL SOCIETY. | May 1904,

Had our littoral sunk forests been contined to a few places where
the topographical conditions were specially favourable for their pro-
duction, we may concede that they would not in themselves furnish
sufficient proof of a shift of level, either on the part of the land or
of the sea. But when we consider their widespread distribution
all round the margin of these islands, even on those shores where it
is difficult to believe that there has been any subsidence or slipping
downward of a land-surface owing to the draining-off of under-
ground water, we may well doubt whether the old belief should
be disturbed, that the facts, taken as a whole, prove a general
submergence.

Fortunately, the evidence available on this subject allows us to
go a step farther. We need not be content with such debateable
proofs as are furnished by the sunk forests between tide-marks, for
land-surfaces can be adduced, which are buried beneath marine
accumulations under circumstances that leave no doubt as to the
tacts of submergence.

In the North-East of Ireland, excavations at Belfast have shown
the existence of a bed of peat lving almost immediately upon the
Glacial deposits, at a depth of 27 feet below high-water mark.
It has a maximum thickness of 18 inches, and consists of the
matted remains of marsh-plants, and of hazel, alder, oak, willow, and
Scottish pine, together with elytra of beetles and mammalian bones.
It is overlain by estuarine clays, the upper portion of which,
containing abundant Thracia convexa, Scrobicularia alba, ete., 1s
believed to have been deposited in at least 5 fathoms of water,
and to be contemporaneous with the raised beaches of the same
region.’ In this instance, mere local settlement from removal of sub-
soil water, or from the slipping forward of the thin seam of peat,
is excluded, and we are presented with evidence of an actual shift
of relative level, amounting probably to more than 30 feet. If this
land-surface was really cowval with the neighbouring post-Glacial
raised beach, the original amount of submergence must have been
still greater, and by a subsequent emergence of the land, to the
extent of from 10 to 20 feet, the peat has been brought up so much
nearer to sea-level.

On the east side of England, besides the sunk forests on the fore-
shore, important evidence of submergence has been furnished by old
land-surfaces lying considerably below the level of the lowest tides.
At the dock-excavations of Hull a sunk forest, abounding in remains

1 G. W. Lamplugh, &e. ‘ The Geology of the Country around Belfast ’ Mem.
Geol. Surv. Irel. (1904) p. 54.

Vol. 60. | ANNIVERSARY ADDRESS. Cl

of oak and other trees, is found at a depth of 40 to 50 feet below

high-water mark, beneath a deposit of marine warp. A higher land-
surface is marked by a second sunk forest, seen on the foreshore
above the warp, and indicating a submergence of about 4 or 5 feet.
At Grimsby, also, a former land-surface, probably continuous with
the older one at Hull, has been reached at a depth of 35 feet and
more below high-water mark. It may point to a submergence
of perhaps as much as 52 feet." In the Fenland district, at least
five buried forests have been observed, each characterized by its own
vegetation.”

On the coast of South Wales, interesting sections have been
laid open in the excavation for the Barry Docks, in Glamorgan.
These furnish conclusive proof of a succession of at least four layers
of peat overlain by estuarine deposits, and in a situation which
precludes any recourse to local settlement by drainage of under-
ground water or downward slipping. The strata are manifestly
undisturbed, and the lowest is an unmistakable land-surface. It
consists of peat full of remains of oak, hazel, cornel, hawthorn, and
willow, together with crushed shells of Hyalinia and, apparently,
Pisidium and Planorbis. The soil underneath this forest-growth
has yielded specimens of Helivw, Hyalinia, Succinea, Limnea, Pupa,
and Valvata. This buried forest-growth lies at a depth of 35 feet
beneath Ordnance-datum, or 55 feet beneath the line of high-water
of ordinary spring tides. It proves a submergence of at least 55
feet, and the peat-bands at higher levels mark successive pauses in
this submergence. That the movement was in progress in Neolithic
time may be concluded from the occurrence of a portion of a polished
celt in the uppermost layer of peat, from which also two bone-needles
are reported to have been obtained.” Mr. Strahan informs me that,
wherever excavations have been made at the mouths of the valleys
on the coast of South Wales, similar layers of peat have been cut
through at depths below low-water mark. It would thus appear
that the submergence bas been general all along the coast-line.

On the Southern English coast similar evidence of a considerable

1 See S. V. Wood, Jun., & J. L. Rome, Quart. Journ. Geol. Soc. vol. xxiv
(1868) p. 157 ; also Clement Reid, ‘ Geology of Holderness’ Mem. Geol. Sury.

(1885) p. 77.
2 §. B. J. Skertchly, ‘Geology of the Fenland’ Mem. Geol. Surv. (1877) p. 169.
3 A. Strahan, Quart. Journ. Geol. Soc. vol. lii (1896) p. 474, and the
‘Geology of Newport’ (1899) and ‘Geology of Cardiff’ (1902) in the Memoirs
of the Geological Survey. Further evidence of the submergence of the rock-
valleys of South Wales, Devon, and Cornwall, will be found in Mr. Codrington’s
paper, already cited on p. xcviii.

cll PROCEEDINGS OF THE GEOLOGICAL society. | May 1904,

change of level has long been known. ‘The evidence was collected
and discussed by William Pengelly in the papers above cited (p. xev).
He inferred, from the position of the sunk forests along the Cornish
coast, that this region had been submerged to the extent of at least
67 feet since the time when these forests existed as land-surfaces.

Further proofs of the eastward extension of this submergence
have more recently been revealed, during the extensive excavations
for new dock-accommodation at Southampton. A bed of peat, 10 feet
thick, has there been found, descending to a depth of 43 feet
below Ordnance-datum. This vegetable accumulation has yielded
many land- and freshwater-shells; abundant trunks of oak with
roots, sometimes 2 feet long. passing down into the loam beneath;
plentiful remains of beech and hazel, together with some birch and
pine. The plants also included bulrush, sedge, bog-myrtle, heaths,
and bracken. From this bed, bones, horn-cores, and part of the
skull of Bos primigenius were obtained; likewise horns and bones
of red deer, task of boar, bones of hare, and horn of reindeer.
Traces of man were found in the same deposit, as shown by the
occurrence of dark flint-flakes, a round perforated hammer-stone,
and a fine bone-needle polished by use.’

There is thus evidence of a comparatively-recent submergence
of the South-West of England, to the extent of at least 50 or 60 feet.
We are probably justified in considering the present position of the
Glacial raised beach in Gower as a further indication of the same
movement, and there seems no reason why we should not connect
the evidence of this beach with that of the terrace lately detected in
Cork. If these tracts are included in our survey, we see that the
submergence probably stretched across South Wales and St. George’s
Channel to the South of Ireland. The evidence from Hull and
Grimsby, which shows that a similar marked submergence has taken
place along part of the East Coast, not improbably indicates that the
change of level extended across Wales and the centre of England.
This submergence appears to be the latest in the long series of
oscillations which have affected the southern portions of our islands.
No proof has yet been obtained that so serious an amount of recent
submergence has extended farther north. In the northern tracts
the latest recorded change of level has been an emergence of the
land in Neolithic time.

1 'T. W. Shore & J. W. Elwes, Papers & Proceedings of the Hampshire
Field-Club, no. iii (1889) p. 43. The history of recent submergences along

this coast-line is sketched by Mr. Shore, in a paper on ‘ Hampshire Mudlands
& other Alluviums’ ¢bid. vol. ii (1894) p. 181.

Vol. 60. ] ANNIVERSARY ADDRESS, clll

II. Beartnc oF THE EVIDENCE ON THE CAUSES OF
EMERGENCE AND SUBMERGENCE.

Let me now endeavour to set forth the conclusions to which
the evidence obtainable in the British Isles points, in regard to the
causes which, in this region, have determined the emergence and
submergence of land. The vertical range of the changes of level
to which I have restricted myself in this Address amounts at
least to as much as 700 feet, that is some 600 feet below
and 100 feet above the surface of the sea. But it will be remem-
bered that, if we include all the deposits that contain recent marine
shells in situ, the range of movement will be found considerably to
exceed 1000 feet. The problem to be solved is whether this wide
amplitude of shift in the relative levels of sea and land should be
attributed to variations in the height of the surface of the oceanic
envelope, or to secular movements of the terrestrial crust.

Any change of sea-level might be expected to be general and
fairly uniform over jong distances. ‘The area of the British Isles is
too restricted to permit us to believe that there could ever have
been any serious difference in that level between the eastern and
western coasts, or between the northern and southern limits of the
country. Whether, therefore, the surface of the sea rose upon the
land or sank away from it, we should find the records of these
changes to extend over the entire region and to be marked on the
whole by a persistent uniformity of level. But an examination of
the evidence fails to furnish proofs of any such extension and
uniformity.

In the first place, the raised beaches, although so perfectly
developed over nearly the whole of Scotland, disappear towards the
north among the Orkney and Shetland Islands where, had they
ever existed, they had every chance of being as well preserved as
anywhere on the mainland. These islands obviously lay outside of
the area affected by the movement that led to the formation of the
beaches. But they could not have escaped from the effects of any
rise in the level of the sea. Again, it is incredible that if the
ereat 100-foot terrace, so prominent a feature in Scotland, had been
formed by an uprise of the surface of the sea, the same terrace
should not have been visible in thousands of favourable positions
in England, Wales, and Ireland. Its entire absence cannot be
accounted for by the presence of former ice-sheets in these regions,
or by, subsequent denudation. This absence may surely be taken as
proof that the terrace never extended over these parts of our islands.

civ PROCEEDINGS OF THE GEOLOGICAL socieTY. [May 1904,

In the second place, had the position of the sunk forests in the
southern half of England and Wales been due to a rise in the sea-
level, similar evidence of submerged land-surfaces at corresponding
depths should have been met with generally round our coast-line.
Neolithic man was an inhabitant of the country before this sub-
mergence was complete, and has dropped his handiwork in the beds
of peat. In the North of Ireland and in Central Scotland, however,
during Neolithic time the land was emerging from the sea, and man
has left his flint-flakes and weapons in the youngest raised beaches.
Thus in the same period of geological time the sea-level must be
supposed to have risen 50 or 60 feet in the south, and to have sunk
25 or 30 feet in the north. But we cannot suppose that within a
distance of 300 or 400 miles there could have been a difference of
75 feet or more in the level of the water.

In the third place, I have very little doubt that when accurate
levellings are taken of the raised beaches, it will be found that their
apparent horizontality is not absolute, but that they rise slowly in
certain directions, more particularly towards the axis of the country.
I think it not improbable also that a difference of level will be
detected between the same beach on the eastern and on the western
coast, and between its most northerly and most southerly parts.
Such evidence of a deformation of the land can only be determined
by the careful geodetic measurements which I long to see carried
out.

In the meantime, on a review of the whole evidence, I feel
confident that the balance of proof is largely in favour of the old
belief that the changes of level, of which our islands
furnish such signal illustrations, have been primarily
due, not to any oscillations of the surface of the
ocean, but to movements of the terrestrial crust con-
nected with the slow cooling and contraction of our
elobe. If this belief is to be overthrown, better evidence must
be brought against it than has been hitherto adduced.

Vol. 60.] PROCEEDINGS OF THE GEOLOGICAL SOCIETY. cy
) February 24th, 1904.
J. E. Marr, Sc.D., F.R.S., President, in the Chair.

Arthur Hutchinson, M.A., Ph.D., F.C.S., Demonstrator in Mine-
ralogy in the University of Cambridge, Fellow & Tutor of Pembroke
College, Cambridge, was elected a Fellow of the Society.

The List of Donations to the Library was read.

The Presipenr read the following resolution of the Council, which
had been forwarded to Mrs. McMahon :—

‘That the Council desire to place on record their regret at the death of
General C. A. McMauon, F.R.S., who for so many years was one of their
colleagues, and took so active an interest in the affairs of the Society ; and the
Council further wish to express their sincere sympathy with Mrs. McMahon
and the family in their bereavement.’

The PrestpEnt also announced that Prof. T. G. Bonney, Sce.D.,
F.R.S., and Mr. H. W. Moncxton, F.L.S., would represent the Society
at General McMahon’s funeral on the following day.

The PresipEnt stated that Prof. Lapworrs had written, thanking
the Fellows for their kind expression of sympathy with him in his
illness, and tor the telegram despatched to him in the course of the
Annual General Meeting.

The following communications were read :—

1. ‘ Eocene and Later Formations surrounding the Dardanelles.’
By Lieut.-Col. Thomas English, late R.E., F.G.S.

2. ‘The Derby Earthquakes of March 24th and May 3rd, 1903,’
By Dr. Charles Davison, F.G.S.

The following specimens, etc. were exhibited :—

Rocks and Fossils from the Dardanelles, and a Model of the sur-
rounding Country, exhibited by Lieut.-Col. T, English, F.G.S., in
illustration of his paper.

At 7.30 p.m., before the Ordinary Meeting, a Sprcran GENERAL
Meetine was held, for the purpose of taking into consideration the
following alterations in the Bye-Laws proposed on behalt of
the Council :—

A. That Bye-Laws Sect. XIV, Art. 4, and Sect. XXI, Art. 6 be repealed.

B. (1) That Bye-Laws, Sect. XII, Art. 3, and Sect. XII, Art. 4, 1° be repealed.
(2) That the following new Bye-Law be enacted, to be called Sect. IX,
Art. 12a, to come between Arts. 12 & 13 of Sect, IX: ‘ Persons not

VOL. LX, h

evl PROCEEDINGS OF THE GEOLOGICAL SOCTETY. [May 1904,

belonging to the Society, if introduced by Fellows or Foreign Members,
inay be present at General Meetings, subject to such regulations as the
Council may make from time to time.’

(3) That the following alteration be made in Bye-Laws, Sect. XIX, Art. 1:
That the words ‘ subject to such regulations as the Council way make
from time to time’ be added after the words ‘General Meetings of
the Society’ at the end of line 4.

These resolutions were ballotted on by the Fellows present, and
agreed to.

March 9th, 1904.

J. E. Marr, Sce.D., F.R.S., President, in the Chair.
The List of Donations to the Library was read.

Mr. G. Barrow exhibited and commented on a small striated
boulder, which was found a little above high-water on White Island,
one of the northern projections of the Scilly Isles. It was firmly
embedded in the ground, and therefore the striations which occur
on both faces could not have been produced in situ by the grinding
action of boulders or stones moved by powerful waves.

The following communications were read :—

1. ‘On the probable Occurrence of an Eocene Outlier off the
Cornish Coast.’ By Clement Reid, Esq., F.R.S., F.L.S., F.G.S."

2. ‘The Valley of the Teign.” By Alfred John Jukes-Browne,
Hisq.,).b. Any EGS,

The following specimens were exhibited, in addition to that
mentioned above :—

Specimens exhibited by Clement Reid, Esq., F.R.S., F.L.S., F.G.S.,
in illustration of his paper.

The following Regulations, as to the Admission of Visitors to
General Meetings of the Society, have been made by the Council, in
accordance with the Bye-Laws, Sect. IX, Art. 12 a and Sect. XIX,
Art. 1, as amended at the Special General Meeting held on
February 24th, 1904 :—

(I) Annuat GeneraL Mzerines.

1. Except by permission of the President, or one of the Secretaries, or of the
Council, no Visitor shall be permitted to be present at an Annual General
Meeting until after the report of the Council has been read, and the discussion
(if any) under Bye-Laws, Sect. X, Art. 20, has taken place.

1 Communicated by permission of the Director of H.M. Geological Survey.

Vol. 60. | _ PROCEEDINGS OF THE GEOLOGICAL SOCIETY. evil

2. As soon as the above-mentioned discussion has concluded, and the motion
that the report be printed has been voted on, Visitors will be admitted, on the
introduction of Fellows or Foreign Members.

(II) Specran Generat MEETINGS.

3. No Visitors will be permitted to be present at Special General Meetings,
except by express permission of the Council, or, if there is no meeting of the
Council between the time of an application to be present at a Special General
Meeting being received and the time fixed for such meeting, by express per-
mission of the President or one of the Secretaries, who shall report to the
Council the granting of such permission-and the reason for so doing.

(IIT) Orprnary Geyerat Mzerines.

4. Visitors will be permitted to be present at Ordinary General Meetings, on
the introduction of Fellows or Foreign Members.

(1V) Genurat.

5. The name of every Visitor present at any General Meeting shall be
inserted in a book to be kept for the purpose, with the name of the Fellow or
Foreign Member introducing such Visitor.

6. No newspaper-reporters, as such, shall be admitted as Visitors at General
Meetings, except by express permission of the Council.

7. 1f necessary, from considerations of space or otherwise, the Council, the
President, or ene of the Secretaries may regulate the number of Visitors that
may be introduced by any one Fellow or Foreign Member at any particular
meeting.

March 9th, 1904.

March 23rd, 1904.
J. E. Marr, Se.D., F.R.S., President, in the Chair.

Gladstone Anthony Allen, Esq., B.Se.(Lond.), 56 Trinity Street,
Old Hill (Staffordshire) ; and Francis Edward Middleton, Esq., Elm
Villa, St. John’s, Wakefield, were elected Fellows of the Society.

The List of Donations to the Library was read.

The following communication was read :—

‘On the Moine Gneisses of the East-Central Highlands and their
Position in the Highland Sequence.’* By George Barrow, Esq.,
F.G.S.

The following specimens, etc. were exhibited :—

Rock-specimens, Microscope-Sections, and Lantern-Slides, exhi-
bited by George Barrow, Esq., F.G.S., in illustration of his paper.

1 Communicated by permission of the Director of H.M. Geological Survey.

eyill PROCEEDINGS OF THE GEOLOGICAL socteTy. [ May 1go4.

April 13th, 1904.
J. EK. Marr, Sc.D., F.R.S., President, in the Chair.

Prof. Henry Fairfield Osborn, of New York (U.S.A.), was elected
a Foreign Member; and Dr. Erich Dagobert von Drygalski, of the
University of Berlin, and Dr. Henry 8. Washington, of Locust,
New Jersey (U.S.A.), were elected Foreign Correspondents of the
Society.

The List of Donations to the Library was read.
The following communications were read :—

1. ‘ The Discovery of Human Remains under the Stalagmite-Floor
ef Gough’s Cavern, near Cheddar.’ By Henry Nathaniel Davies,
Ksq., F.G.S.

2. ‘The History of Volcanic Action in the Phlegraan Fields.’

By Prof. Giuseppe De Lorenzo, of the Royal University of Naples.
(Communicated by Sir Archibald Geikie, Sc.D., Sec.R.S., V.P.G.S.)

The following specimens and maps were exhibited :—

Specimens and Flint-Implements from Gough’s Cavern, near
Cheddar, exhibited by H. N. Davies, Esq., F.G.S., in illustration of
his paper.

Sheets 120 & 133 of the Geological Survey-Map of Saxony,
presented by the Director of that Survey.

| April 27th, 1904.
J. E. Marr, Se.D., F.R.S., President, in the Chair.

The List of Donations to the Library was read.

Prof. W. W. Warts, in exhibiting the platinotype-prints issued
by the Geological Photographs Committee of the British Association,
said that these constituted the third issue of the first series. These
photographs would be in the hands of subscribers within the next
few days.

The following communications were read :—

1. ‘Ona New Species of Hoscorpius from the Upper Carboniferous
tocks of Lancashire.’ By Walter Baldwin, Esq., F.G.S., and William
Henry Sutcliffe, Esq., F.G.S.

2. ‘The Genesis of the Gold-Deposits of Barkerville (British
Columbia) and the Vicinity.’ By Austin J, R. Atkin, Esq. (Com-
municated by the Secretary.)

Vol. 60. } PROCEEDINGS OF THE GEOLOGICAL SOCIETY. C1lx

In addition to the photographs mentioned on p. eviil, the following
specimens, etc. were exhibited :—

Specimens and Lantern-Slides exhibited by W. Baldwin, Ksq ,
F.G.S., and W. H. Sutcliffe, Esq., F.G.8., in illustration of their
paper.

Sheets 1 to 4 of the new colour-printed Drift-Map of the London
District, presented by the Director of H.M. Geological Survey.

Eight sheets of the —_ Map of the Royal Geological Survey of
Italy, presented by the Director of that Survey.
Revised edition of the Geological Map of the Southern Transvaal,

by Dr. F. H. Hatch, M.Inst.C.K., F.G.8., presented by the Author.

May 11th, 1904.
Horace B. Woopwarp, Esq., F.R.S., Vice-President, in the Chair.

Leonard J. Bates, Esq., Mining Engineer, Oakdene, Claughton,
Birkenhead ; Charles Joseph Gray, Esq., Pietermaritzburg (Natal);
Ivan Ascanio Stigand, Esq., B.A., Balek Pappan, Koetei (Dutch
Borneo); and Robert B. Young, Esq., M.A., B.Sc., P.O. Box 3572,
Johannesburg (Transvaal), were elected Fellows of the Society.

The List of Donations to the Library was read.

The CuHarrMan referred in feeling terms to the grievous loss
sustained by the Society in the death of Sir Cremenr Le Neve
Foster, F.R.S., Protessor of Mining at the Royal College of Science.
He was elected a Fellow in 1863, and as early as 1865 he commu-
nicated to this Society, conjointly with William 'lopley, the now
classic paper on the Medway Gravels & the Denudation of the
Weald—a paper which had largely influenced the views of geologists
on the physiography of the South-East of England.

The CHarRMAN announced that the Council had resolved to award
the proceeds of the Daniel-Pidgeon Fund for 1904 to Mr. Linspatn
Ricuarpson, F.G.8., of Cheltenham.

The following communications were read :—

1. ‘On some Quartzite-Dykes in Mountain-Limestone near
Snelston (Derbyshire). By Henry Howe Arnold-Bemrose, Ksq.,
BA. 1GS.

2. ‘Phenomena bearing upon the Age of the Lake of Geneva.’
By Dr. C. S. Du Riche Preller, M.A., Ph.D., A.M.1.C.E., M.LE.E.,
F.R.S.E., F.GS.

VoL. LX. a

Cx PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [ Aug. 1904,

The following specimens were exhibited :—

Rock-Specimens, Microscope-Sections, and Lantern-Slides, exhi-
bited by H. H. Arnold-Bemrose. Esq., M.A., F.G.S., in illustration
of his paper.

Paleolithic Implements from Drift-Deposits at Knowle Gravel-
Pits, Marlborough, obtained by Mr. J. W. Brooke, and exhibited by
George Clinch, Esq., F.G.S.

Voleanic rocks from, and Photographie Views of, the Island of
Ascension, obtained by Mr. W. Hebdon, and exhibited by Dr. A.
E. Salter, F.G.S.

May 25th, 1904.
J. E. Marr, Se.D., F.R.S., President, in the Chair.

The List of Donations to the Library was read.

The following communications were read :—

1. ‘On the Occurrence of a Limestone with Upper Gault. Fossils
at Barnwell, near Cambridge.’ By William George Fearnsides, Ksq.,
MA. GS.

2. ‘On the Age of the Llyn-Padarn Dykes.’ By James Vincent
Elsden, Esq., B.Sc., F.G.S.

The following specimens were exhibited :—

Rock-Specimens and Microscope-Slide of the Hard Band associated
with the zone of Schlenbachia varicosa, from Barnwell, near Cam-
bridge, and Fossils representative of the fauna of these beds, exhibited
by W. G. Fearnsides, Esq., M.A., F.G.S., in illustration of his
paper.

Kock-Specimens, Microscope-Sections, and Lantern-Slides of Llyn-
Padarn Dykes, exhibited by J. V. Elsden, Esq., B.Se., F.G.8., in
illustration of his paper.

June 8th, 1904.
J. EK. Marr, Sc.D., F.R.S., President, in the Chair.

Fritz Joseph Ernst, Esq., F.R.G.S., Lorraine, Jordan-Hill Road,
Hobart (Tasmania); Isaac Vaughan Evans, Esq., 149 Richmond
Road, Cardiff; and Henry Marks Kruszinski, Esq., 62 Highbury
New Park, N., were elected Fellows; Prot. Joseph Paxson Iddings,
University of Chicago, Illinois (U.S.A.), was elected a Foreign
Member; and Dr. William Bullock Clark, Baltimore, Maryland

Vol. Go. | PROCEEDINGS OF THE GEOLOGICAL SOCIETY. exi

(U.S.A.), and the Hon. Frank Springer, East Las Vegas, New
Mexico (U.S.A.), were elected Foreign Correspondents of the
Society.

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, Sect. VI, Art. 5,
in consequence of the non-payment of the Arrears of their Con-
tributions.

The PresipEnt announced that the Council had made the following
Regulations as to Exhibits at Meetings :—

1, That at Ordinary General Meetings when geological communications are
read, the Chairman, when drawing attention to any specimen or drawing
exhibited, may invite the Fellow who makes the exhibit to make a brief
statement concerning it, at such time during the Meeting as the Chairman
shall determine; but no discussion shall be allowed, except at the request
of the Chairman.

2. Attention will not be called to any exhibit not illustrating a paper, unless it
has been shown to the Chairman or to one of the Secretaries before the beginning
of the Meeting.

The following communications were read :—

1. ‘The Palzontological Sequence in the Carboniterous Lime-
stone of the Bristol Area.’ By Arthur Vaughan, Esq., B.A., B.Sc.,
F.G.S.

2. *On a small Plesiosaurus-Skeleton from the White Lias of
Westbury-on-Severn.” By Wintour Frederick Gwinnell, Esq.,
F.G.S.

3. ‘The Evidence for a Non-Sequence between the Keuper and
Rhetic Series in North-West Gloucestershire and Worcestershire.’
By Linsdall Richardson, Esq., F.G.S.

The following specimens, etc., were exhibited :—

Specimens, Photographs, and Lantern-Slides, exhibited by Arthur
Vaughan, Esq., B.A., B.Sc., F.G.S., in illustration of his paper.

Specimens of Spirifer tornacensis, from the Carboniferous Lime-
stone of Tournay (Belgium), and of Sp. mosquensis, exhibited by
John Francis Walker, Esq., M.A., F.L.S., F.G.S., in illustration of
Mr. Vaughan’s paper.

Plesiosaurus-Skeleton from the White Lias of Westbury-on-
Severn, exhibited by Wintour Frederick Gwinnell, Esq., F.G.S., in
illustration of his paper.

Geological Survey of Ireland: 1-inch colour-printed map of the
Belfast District, presented by the Director of H.M. Geological
Survey.

exil PROCEEDINGS OF THE GEOLOGICAL SOCIETY. {| Aug. 1g04.

June 22nd, 1904.
J. E. Marr, Se.D., F.R.S., President, in the Chair.

Edmund John Spargo, Esq., Consulting Mining Engineer, 56
Ferndale Road, Sefton Park, Liverpool, was elected a Fellow of the
Society.

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, Sect. VI, Art. 5,
in consequence of the non-payment of the Arrears of their Con-
tributions.

The following communications were read :—

1. ‘The Igneous Rocks of Pontesford Hill (Shropshire).’ By
Prof. William 8. Boulton, B.Sc., Assoc.R.C.S., F.G.S. ;

2. ‘The Tertiary Fossils of Somaliland, as represented in the
British Museum (Natural History).’ By Richard Bullen Newton,
Ksy., F.G.S.

3. ‘The Caernarvon Earthquake of June 19th, 1903, and its
Accessory Shocks.’ By Charles Davison, Se.D., F.G.S.

The following specimens, etc. were exhibited :—

Specimens, Microscope-Sections, and Lantern-Slides, exhibited by
Prot. W. S. Boulton, B.Se., A.R.C.S., F.G.S., in illustration of his
aper.
é meaty Fossils from Somaliland, exhibited by R. Bullen Newton,
Tsq., F.G.S., in illustration of his paper.
Five new Sheets of the Geological-Survey Map of Japan, presented
by the Director of that Survey.

THE

QUARTERLY JOURNAL

OF

THE GEOLOGICAL SOCIETY OF LONDON.

VoL. LX.

1. On the OccuRRENCE of EpESTUS tn the Coat-MeEasuREs of Briain.
By Epwin Turrtey Newron, Esq., F.R.S., V.P.G.S.1 (Read
November 18th, 1903.)

[Prats I.]

{np presence of marine beds in the Coal-Measures of North Stafford-
shire was first made known by Mr. J. Ward [1],* of Longton, in
1865; but their occurrence in other districts had already been
observed by the officers of the Geological Survey [2 & 3}.

These marine bands are chiefly met with during the sinking of
shafts ; and Mr. J. T. Stobbs, -.G.8., of Stoke-on-Trent, has for some
time past been studying those that occur in North Staffordshire. It
is due to the vigilant observations of that gentleman, and to the
assistance of the pupils of his mining class, that these beds are
found to occur with much greater frequency than has hitherto been
supposed.

Mr. Stobbs very courteously called the attention of the Geological
Survey to one of these marine bands, found at about 18 yards
below the ‘ Twist Coal,’ in the Smallthorne sinking of Messrs. Robert
Heath & Son’s pits at Nettlebank (North Staffordshire).

An interesting series of fossils has been found in the shales and
impure limestones brought to bank from this particular band; and
with the permission of the colliery-owners, the fossil-collector of
the Geological Survey, Mr. J. Pringle, went to Smallthorne to secure
a series of these fossils. Among the specimens thus obtained,
there is one which calls for special notice, as it establishes for
the first time the occurrence in Britain of the remarkable genus of
fishes known as Hdestus. This genus was originally described

‘ Communicated by permission of the Director of H.M. Geological Survey.

? These numbers in square brackets throughout the paper refer to the
bibliographical list on p. 7.

Q.J.G.8. No. 237. B

2 MR. E. T. NEWTON ON THE OCCURRENCE OF_ ([ Feb. 1904,

from the Coal-Measures of the United States, but was afterwards
recognized in beds of similar age in Russia and Australia. The
accompanying figure (fig. 1, below) of the first-described specimen
(Edestus minor) will call to mind the form of this ichthyodorulite,
which has been thought to be a dorsal defence. To it have also
been assigned various other functions in the economy of the fish to
which it belonged; its true nature, however, remains uncertain.

The segmented character of Edestus minor is shown in this
figure ; and separate segments of this and other species have been
met with in North America, showing that each tooth was attached
to a firm base, elongated in one direction and grooved above for
the reception of the under part of a similar segment. Several such
segments were united in the original specimen.

Fig. 1.—Side view of Edestus minor. (5 nat. size.)

[From Geol. Surv. Illinois, vol. iv (1870) pl. i, fig. 2.]

A = Anterior, oldest segment. B = Posterior, newest segment.

It is now more than 48 years (August 1855) since Hitchcock [4 |
first made known the remains of the remarkable fish from the
‘ Coal-formation’ of Park County (Indiana), to which Newberry [8]
afterwards gave the name of Hdestus minor. It was Leidy [5],
however, who proposed the generic name of Hdestus for a large and
closely-allied form from the Coal-Measures of Arkansas, which he
described under the name of Hdestus vorax.

In the year 1870, Newberry and Worthen [9] made known
another species, Hdestus Heinrichsti, from the Coal-Measures of
Illinois. Up to that time the genus had only been known in
North America; but in 1878 Dr. H. Trautschold [10] recognized,
among the fossils described by him from Miachkova, near Moscow,
a single denticle, referable to this genus, which he named Adestus
protoptrata; and subsequently, in 1884 [12], the same writer’

Vol. 60.] | EDESTUS IN THE COAL-MBASURES OF BRITAIN. 3

obtained, also from near Moscow, a more perfect specimen with a
large part of its grooved basal segment: thus more firmly establish-
ing the oceurrence of the genus in Europe.

In was in 1886 that Dr. Henry Woodward [14] described the
remarkable ichthyodorulite from the Carboniferous rocks of Western
Australia, to which he gave the name of Adestus Davisti. The
specimen differed in several points from the forms hitherto referred
to Hdestus, more especially in its deeper curvature and in the
larger number of its denticles ; but Dr. Woodward was correct in
regarding it as nearly related to Hdestus, although it is now placed
in a distinct genus.

Another species which, on account of its large size, received the
name of Edestus giganteus, was described by Newberry [17] in
1889, from the Coal-Measures of Decatur, Macon County (Illinois) ;
and in 1898 Dr. Bashford Dean [20] gave an account of another
much-curved form, under the title of Edestus Lecontei, from the west
of the Rocky Mountains, in Nevada.

In 1899, Dr. Karpinski [21] published his detailed memoir on
the Kdestide and on anew genus, Helicoprion. Severai examples
of these ‘spiral saws’ had been found in the ‘ Artinskian stage’
(Permo-Carboniferous) near the town of Krasnoi Ufimsk, in Eastern
European Russia, a little west of the Urals. These extraordinary
tooth-bearing spirals still remain an unsolved problem, notwith-
standing the lively discussion to which Dr. Karpinski’s memoir has
given rise, and which continues to the present time, several eminent
workers abroad and at home having expressed their views on the
subject [see 27-31]. Not the least important of these contributions
were the papers published by Dr. Eastman in 1901 and 1902
[22-26]. In one of these [24] a new genus, Campyloprion, is
established for certain fossils closely allied to Helicoprion. In this,
and the subsequent memoir, Dr. Eastman describes the Ovodus-like
jaw of Campodus, with its somewhat compressed and enrolled
symphysial series of teeth, which are regarded as of Cestraciont
type, and are thought to indicate the principie of enrolling of the
teeth on or near the symphysis, which culminated in the ‘ spiral
saw’ of Helicoprion; Edestus and Campyloprion showing inter-
mediate stages, in which the teeth were broken off or worn away,
instead of being retained and rolled into a spiral.

The presence of Helicoprion in the Carboniferous rocks of Japan
has been made known by M. H. Yabe [32], and I am indebted to
Dr. A. Smith Woodward for this reference.

The specimen, found by Mr. Pringle at Nettlebank, was, when it
first came into my hands, in several pieces, and much of it was still
hidden in the hackly, dark lhmestone.* The fossil itself being very
brittle, the greatest care was necessary for its development; it is
now, however, in a condition to show its complete form, with the
exception of the point of the tooth, which was not found.

1 Dr. W. Pollard, F.G.S., who has kindly examined the rock, says that, it is
an impure limestone, containing some magnesia and ferrous carbonate.
B2

4 MR. E. I. NEWTON ON THE OCCURRENCE OF [ Feb. 1904,

The specimen is evidently a single segment of a fossil very closely
resembling Hdestus minor, and consists of an elongated basal portion
bearing at one extremity a smooth, enamelled, and serrated crown.
The inferior border of the base is concave from end to end, and the
superior border is convex in the same direction. Below the crown
the base is flattened on each side and angular at the inferior border.
This angularity becomes less marked towards the middle, and the
lower border is then more and more rounded to the opposite end,
this portion of the base being thicker and deeper than the part
which carries the crown. Two or three vascular grooves are seen
upon the side, extending from apertures which penetrate to the
deeper parts of the base. The whole of the base has an open
spongy texture, the interstices being filled with the dark matrix.

The line of demarcation between the crown and the base is
clearly defined by the edge of the enamel, the roughness of the
base increasing as it approaches this dividing-line, which is not
quite parallel with the lower margin, but approaches it somewhat
as 1t nears the extremity, and then, curving downward, the enamel
completely embraces the end of the base, while beyond it extends the
distal part of the crown.

The free cutting-edges of the crown, so far as preserved, are
strongly denticulated, there being on the upper margin twelve den-
ticles in 14 millimetres. A closer examination with a lens shows
that each of these denticles is again divided into three serrations.
the median one being about twice as large as the outer two. So
much of the lower margin as is preserved shows six denticles in
5 millimetres, but there is no evidence of these being serrated.

The outer edge of the enamelled crown forms a narrow pointed
spur, extending in the direction of the elongated base as far as the
end of the upper denticulated cutting-edge, but separated from it
by a tongue of the roughened base, which passes in between them
for about a third of the length of the crown. Probably there is a
similar spur of enamel on the opposite side of the tooth, but this is
hidden in the matrix. The end of the crown being absent, its
form cannot be known, but, judging from what remains, it seems to
have resembled that of Edestus minor; the dotted line in PI. I, fig. 1
gives a restoration on this basis.

Seen from the end, the crown is much compressed, and the
section exposed by the broken surface is lenticular (PI. I, fig. 6).
Below the broken end the denticles extend quite to the lower margin,
and on each side, just above the lowest denticle, is a little rounded
cusp.

When the specimen is viewed from above, a deep trough is seen
to extend throughout its length, excepting the portion occupied by
the crown, close to which the trough descends about halfway into
the thickness of the base, and becomes deeper as it passes away
from the crown, occupying the whole depth at the opposite
extremity. This end of the specimen has the two sides very unlike
(see Pl. I, fig. 1), for, while the side next to the matrix ends in a
rounded point, the side freed from matrix is deeply notched. A part

Vol. 60.| #£DESTUS IN THE COAL-MEASURES OF BRITAIN. 5

of this side has been accidentally cut away, but the notch is not due
to this cause, for the fragment cut off is similarly, though not so
deeply, notched. Some splinters of bone near by may, however,
indicate that fracture took place before fossilization.

The upper view shows the specimen to be nearly equilateral, so
nearly so indeed that the inequalities may be, and probably are,
due to distortion, or imperfection, in fossilization. But this want
of equality must not be lost sight of, for if such specimens be not
practically equilateral, we lose the chief evidence for the median
position of these ichthyodorulites in the fish to which they belonged.

Measurements oF EDESTUS FROM SMALLTHORNE, IN MILLIMETRES.

Length of lower margin a-d, Pl. I, fig. t...... 59-0
ERGY OF DASE Ab IG va o- ccaane ccketevacees ayes 12:0
Whinkness of base at f-g ~2...52..0ccss sens Sees ee 10°5
fee A Sd BS To Se 11-0
DGMEMGE PEGOVE AG Mn ose. cones anccceednuavens DD
Lower edge of crown, G-€..........-.c0.ceeeeeeee 18:0
Upper margin preserved, c-d_ ............+-+++ 14:0
Lower margin preserved, @-€ .............0506 50
Broken end of crown, d—€....,.....0cceseceeesees 8-0
Broken end of crown, thickness ............... 2:3
RV POE MEIN echo des wove Sosa oe shesien 70

The shape of the base below the crown and the form of the
trough of the upper surface show clearly that this specimen is
one segment of a series, fitting one into the upper groove of
another, as in Hdestus. And the close resemblance between this
fossil and Edestus minor leaves no room for doubting their generic
identity ; but the question of species is more troublesome.

That our fossil is more nearly allied to Hdestus minor than to
any other known species of the genus is evident; but the want of
a perfect crown prevents « completely-satisfactory comparison. The
type-specimen of LHdestus minor, described by Newberry, had a
very little of the lower part of the crown or base preserved ; but
the upper part is lanceolate, and is described as having double
denticles; this is unlike the Smallthorne fossil, which has the
denticles in triple form. Hitchcock’s original specimen (see
text-fig. 1, p. 2), which was subsequently referred to /. minor by
Newberry, has the crowns of the teeth rather more obtusely
lanceolate than in the type, and each crown is said tv have a
lateral spur of enamel similar to that seen in the Smallthorne
specimen, but the denticles are double. So far as one can judge of
the form of a segment in #. minor, it is unlike this British fossil.
The much smaller specimen from Moscow, referred by Dr. Karpinski
to E. minor, has a narrowcr and more acuminate crown than either
of the American specimens, but shows the same slender spur of
enamel, and the denticles are said to be as in EL. minor. The base
below the crown is very like the same part in the Smallthorne fossil ;
but, on close comparison, it will be seen that the lower edge of the
enamel forms nearly a straight line in the Russian tooth, while a

6 MR. E, T. NEWTON ON THE OCCURRENCE OF [ Feb. 1904,

few of the lower denticles are at right angles with the rest of the
crown. In the British specimen, on the other hand, the lower
edge of the enamel is strongly bent, while the lower denticulated
margin is only slightly curved at its lower end. There is likewise
a difference in the denticles ; the Russian specimen having them, as
in Edestus minor, double and not triple.

Dr. Karpinski was evidently in some doubt as to his specimen
being really an example of £. minor, for he says that it is either
this or a closely-allied species, and I am inclined to think that the
latter suggestion is the more justifiable. But, however that may
be, the Smallthorne specimen can scarcely be referred to Hdestus
minor, the differences mentioned above preventing such a reference.
Bearing in mind, therefore, the most striking peculiarity of our
fossil, | propose to name it Edestus triserratus.

Fig. 2.—Segments of Edestus triserratus restored. (2 nat. size.)

A = Anterior, oldest segment. B = Posterior, newest segment.

Fortunately the basal portion of our specimen and its trough are
so well shown, that the manner in which the segments fitted
together is obvious ; and, taking advantage of this, the appearance
of half a dozen such segments combined is shown in text-fig. 2.

The crowns of all the teeth in Newberry’s figure of #. minor are
so nearly of the same size, that one is justified in assuming that
the teeth and segments of our British specimens did not vary greatly
in this respect, and consequently the combined series would have
had much the appearance of my restoration; but probably the
basal portions of the older segments of Hdestus changed somewhat
in shape by continued deposition or absorption of bony material.
At first sight it is not clear which is the growing end of such
a series. Among a large number of segments of H. Heinrichsii
that Newberry had for examination was one which possessed no
groove ; and he concluded that this was the first of a series,
that a new segment was formed with its base under the toothed

Vol. 60.] | EDESTUS IN THE COAL-MEASURES OF BRITAIN. 7
end of the older one, and that this by growth gradually ensheathed
the one above. ‘This seems most likely to be the correct interpre-
tation, although doubt has been thrown upon the supposed non-
grooved segment, which was thought to be the first formed.

That the curved and toothed ichthyodorulites, to which the name
of Edestus is properly restricted, belonged to a fish closely allied to
that which carried the ‘spiral saw, WHelicoprion, is generally
agreed, but it is by no means proved that the two forms had a
similar function.

Dr. Eastman has shown good reason for thinking that the
enrolling of the symphysial teeth of Campodus is an indication of
the nature of the spiral of Helicoprion, although he was not the
first to suggest this interpretation. There is, however, but a
distant relationship between these two genera, even if his idea that
they are both Cestracionts should prove correct. That Campylo-
prion is nearly related to Helicoprion will be readily admitted ;
indeed, there seems no obvious reason why the fossils referred to
this genus may not have been parts of spirals similar to that of
Helicoprion, and if so they might conveniently have remained in
that genus.

With regard to Edestus, the form of each tooth-crown and base
is so unlike those in Helicoprion that its generic distinction will
not be disputed ; but, at the same time, its near relationship to
Helicoprion has not been questioned.

However anomalous the ‘spiral saw’ of Helicoprion may be, it
seems most in accordance with our present knowledge to regard it
as the enrolled dentition at or near the symphysis of an elasmo-
branch, possibly allied to Cestracionts. That the forms referred to
Edestus are of the same nature seems less probable; and, while
admitting that this interpretation may prove correct for them also,
it still seems to me that these straighter forms, with large anteriorly-
projecting bases, are more likely to be dorsal defences,

BIBLIOGRAPHICAL List.

So

J. Warp. [On Marine Bands in the Coal-Measures of North Staffordshire. }

Geol. Mag. vol. 11 (1865) pp. 234 & 286.

. E. Hurt & A. H. Green. Trans. Manch. Geol. Soe. vol. iii (1862) p. 348.

. E. Horn & J. W. Satter. Mem. Geol. Surv. ‘Geology of the Country
around Oldham ’ 1864, p. 64.

. E. Hircncocrx. ‘Account of the Discovery of the Fossil Jaw of an Extinct
Family of Sharks from the Coal-Formation’ Proc. Amer. Assoc. Adv. Sci.
(Ninth Meeting, Providence, 1855) Cambr. 1856, p. 229.

. JOSEPH LErIpy. ‘ Indications of Five Species, with Two New Genera, of Extinct
Fishes’ Proc. Acad. Nat. Sci. Philad. vol. vii, 1854-55 (1856) p. 414. Also Journ.
Acad. Nat. Sci. Philad. ser. 2, vol. iii, 1856 (1858) p. 159 & pl. xv.

6. ‘Remarks on certain Extinct Species of Fishes’ Proc. Acad. Nat. Sci.

Philad. vol. viii, 1856 (1857) p. 301.

7. R. Owen. ‘ Paleontology’ 2nd ed. Edinburgh, 8vo (1861) pp. 123-24 & fig. 38.

8. J.S. NEwBERRY. Geol. Surv. Illinois, vol. ii (1866) p. 84 & pl. iv.

9

0

Hh Who

Or

. J.S. Newserry & A. H.Worruen. Ibid. vol. iv (1870) p. 350 & pl. i, fig. 2.
. H. TravurscHorp. ‘Die Kalkbriiche von Mjatschkowa ’ Nouv. Mém, Soc. Imp.
Nat. Moscou, vol. xiv (1879) p. 49 & pl. vi, fig. 8.
11. M. Lowest. ‘ Recherches sur les Poissons des Terrains paléozoiques de Belgique ’
Ann. Soc. Géol. Belg. vol. x1 (1883) p. 314.

12.

14.

MR. E, T, NEWTON ON THE OCCURRENCE OF [ Feb. 1904,

H. Travurscuorp. ‘Ueber Edestus und einige andere Fischreste des Moskauer
Bergkalks ’ Bull. Soc. Imp. Nat. Moscou, vol. lviii, pt. ii, 1883 (1884) p. 160 &
pl. v, figs. 1 & 2.

‘Ueber das Genus Edestus’ Ibid. vol. 1x1, pt. ii, 1885 (1886) p. 94.

H. Woopwarp. ‘On a Remarkable Ichthyodorulite from the Carboniferous
Series, Gascoyne (Western Australia)’ Geol. Mag. 1886, p. 1 & pl. i.

. Fanny R.M.Hitrcncocr. ‘On the Homologies of Edestus’ Proc. Am. Assoc.

Ady. Sci. (Thirty-sixth Meeting, New York, August 1887) Salem, 1888, p. 260.
Also Amer. Nat. vol. xxi (1887) p. 847.

. H. Trautscnonp. ‘ Ueber Edestus protopirata, Trd.’ Zeitschr. Deutsch.

Geol. Gesellsch. vol. xl (1888) p. 750.

. J. S. Newserry. ‘On the Structure & Relations of Edestus, with a De-

scription of a Gigantic New Species’ Ann. N.Y. Acad. Sci. vol. iv, no. 4, 1888
(1889) p. 113 & pls. iv-vi. See also ‘The Paleozoic Fishes of North America’
Monogr. U.S. Geol. Surv. vol. xvi (1889) p, 217 & pls. xxxix—xi.

. H. TravutscHouip. ‘Ueber Protopirata centrodon, Trad.’ Bull. Soc. Imp.

Nat. Moscou, n. s. vol. iv, 1890 (1891) p. 317.

. A.SmirH Woopwarp. Catal. Foss. Fishes Brit. Mus. pt. ii (1891) p. 151.
. BASHFORD DEan. ‘Ona New Species of Edestus (FE. Lecontei) from Nevada’

Trans. N.Y. Acad. Sci. vol. xvi (1898) p. 61 & pls. iv—-v.

. A. Karpinski. ‘Ueber die Reste von Edestiden und die Neue Gattung Heli-

coprion’ Verh. K.-Russ. Mineralog. Gesellsch. ser. 2, vol. xxxvi (1899) p. 361 &
pls. i-iv; also Mém. Acad. Imp. Sci. St. Pétersb. ser. 8, vol. vili, no. 7 (1899)
pp. 1-76 & pls. i-iv.

. C. R. Eastman. [Review of Karpinski’s Memoir.| Amer. Nat. vol. xxxiv

(1900) p. 579.

~—. ‘On Campodus variabilis, N. & W. Denver Meeting Amer. Assoc. Adv.

Sci. n.s. vol. xiv (1901) p. 795.

‘On Campyloprion, a New Form of Edestus-like Dentition’ Geol. Mag.
1902, p. 148 & pl. vill.

‘Some Carboniferous Cestraciont & Acanthodian Sharks’ Bull. Mus,
Comp. Zool. Harvard Coll. vol. xxxix, no. 3 (1902) p. 55 & pls. i—vii.

. ‘Carboniferous Fishes from the Central Western States’ Ibid. vol. xxxix,
no. 7 (1908) p. 184 & pl. i.

. [Review of Karpinski’s Memoir.| Bull. Soc. belge de Géol. vol. xiii (1903) for

1899, p. 205.

. E. Van pEN Brorck. [Onthesame.| Ibid. p. 215. y
. A. Smitu Woopwarp. ‘Note sur lHelicoprion et les Edestidés’ Ibid,

p. 230.

. G.Stmorns. ‘Note sur Helicoprion Bessonowi (Karpinsky)’ Ibid. p. 235.
. C. Van pE WIE LE. ‘Apercu sur les Vestiges fossiles d’Edestidés, & le nouveau

Genre Helicoprion’ Ibid. p. 244.

. H. Yase. ‘On Fusulina-Limestone with Helicoprion in Japan’ Journ. Geol.

Soc. Tokyo, vol. x, no. 118, Jan. 20th (2563) 1908, p. 8.

EXPLANATION OF PLATE I.
Edestus triservratus, sp. nov.

From the Coal-Measures of Nettlebank (Staffordshire), preserved in
the Museum of Practical Geology, Jermyn Street, London.

Fig. 1. Side view. Natural size.

2. Seen from above. Natural size.

3. Side view of crown and part of base. Twoand a half times the natural
size.

4. Crown and part of base seen from above. Two and a half times the
natural size.

5. Section of base at h. Two and a half times the natural size.

6. View of broken end (a, e, d). Two and a half times the natural size.

7. Denticles showing triserration. Six times the natural size.

A T.Hollick del.et lth.

Quart.Journ.Geol.Soc.Vol.LX,P1.].

Mintern Bros. imp

EDESTUS TRISHRRATUS,nov. sp.

Vol. 60.j| #DESTUS IN THE COAL-MEASURES OF BRITAIN. 9

DISCUSSION.

Dr. A. Smirx Woopwarpd confirmed the Author's interpretation
of the fossil exhibited, and remarked on the imperfection of our
knowledge of the marine Upper Carboniferous fishes. The frag-
mentary character of the known remains of Edestide prevented
the formation of any definite judgment as to their true nature.
He regarded the fossils named Edestus and Helicoprion as the fused
teeth of sharks, and alluded to the discovery of analogous whorls
of teeth in the mouth of a Lower Devonian shark described by
Dr. Traquair. He did not think that the more flattened rows of
teeth needed a different interpretation from that of the more spiral
whorls. ,

The AvrtHor, in reply, called attention to the use which the
living ‘ sawtish’ (P7?stis) makes of its toothed rostrum, as indicating
a possible function of the Helicoprion-spiral, if (as has been supposed)
this was placed in front of the head.

10 MR, E. H. CUNNINGHAM-CRAIG ON [Feb. 1904,

2. Mrramorpuism in the Locu-Lomonp Disrricr. By E. Huzerr
Conninenanu-Craia, Esq., B.A., F.G.S.° (Read November 4th,

1903.)
| Pitares II-V: Microscops-Szcrions. |
ConTENTSs.
Page
A Dntrodehion yok. 2. sacseaeeed oat gs ade 10
it. Dynamic Metamiorpliam.. 5). 2...:..2.0peae ee ll
ELT. ‘Constructive Metamorphism: .).¢.21..20-2=-cs cee eee ee 12
[V. Nature of the Folding, and Stratigraphical Relations ........... 13
V. Petrographical Desemptioniae 2 Scene seo ee 15
(z) The Leny-Grit Group.
(2) The Aberfoil-Slate Group.
(c) The Beinn-Ledi Group.
(d) The Green Beds.
Vi. Chemical Analyses .............. Fe Oe Pe See See ae es: 22
VII. The Zones of Progressive Metamorphism.................00.00e000 24
VT. -Contact-Metamionphiem > a5, 9c 5. eect oe eee 25
IX. Nature of the Albite-Gneiss Metamorphism ..................08. 26
A; ROCA pI tULALONS 5 isds- chs acre a ee eee ee Te 27

I. Inrropwcrion.

THIs communication has been written, not so much with the idea of
describing any phase of metamorphism specially interesting in itself,
as of contributing to our knowledge of what metamorphism is, and
of distinguishing between different kinds of metamorphism.

The term ‘ metamorphism,’ or even ‘ progressive metamorphism,’
has so often been used in a somewhat vague sense, without any dis-
tinct specification as to whether dynamic, thermal, hydrothermal,
or contact-metamorphism, or a combination of two or more of these,
is meant, that a study of an area where each of these types can be
readily distinguished by its effects and considered separately, may
prove of interest, as indicating the nature of those problems which
workers among the Highland rocks have to investigate.

In the ‘ Loch-Lomond District’ I inciude all the Highland rocks
on both sides of the loch, as well as the area lying to the eastward,
including the Trossachs—in fact that part of the Highlands which is
embraced by Sheet 38 of the Ordnance-Survey map. The material
for this paper was collected two years ago, after four years of work
in the district, and the main conclusions will appear in the ‘ Expla-
nation of Sheet 38° by the Geological Survey of Scotland.

It is well-known that, in passing north-westward from the
Highland Boundary-Fault, the metamorphism is seen to increase in
degree. The progressive metamorphism in the Loch-Lomond district
can be considered under two heads—dynamic, and what, for want of
a better word, I call ‘constructive’ metamorphism. These processes -

* Communicated by permission of the Director of H.M. Geological Survey.

Vol. 60.] METAMORPHISM IN THE LOCH-LOMOND DISTRIC?. 11

have in all likelihood taken place contemporaneously to some extent,
or at least the duration of the latter process has overlapped that of
the former: but it is convenient, in dealing with the progressive
alteration, to consider each process separately, as they can be dis-
tinguished by their effects.

The dynamic metamorphism is, in effect, chiefly a de-
structive process as regards the allothigenic mineral-constituents
and their arrangement in a rock: it is an almost purely-mechanical
action, which sets up new structures, but may not have had the
slightest effect in the development of authigenic minerals.

The constructive metamorphism, which may be thermal
or hydrothermal, is constructive in the sense of developing
authigenic minerals; but in its effect upon structures, whether
original or produced by dynamic metamorphism, it may tend either
to emphasize or to obliterate them.

The foregoing explanation is necessary, as giving the precise
meanings of these terms as I shall use them in this communication,
meanings which do not necessarily coincide with those applied to
the same terms by other observers.

II. Dynamic METAMORPHISM.

The effects of dynamic metamorphism upon any bed depend on
(1) its lithological character, and (2) the nature and position of the
folding at the particular place where the bed is observed. If the
bed be massive, coarse, and gritty, it will be able to resist the
deforming torces more successfully than if fine-grained, less homo-
geneous, or of naturally softer material.

The effect of the nature of the folding is not so apparent, but
can be explained readily by a consideration of the physical con-
ditions in each case, on the assumption that the motive force is
a pressure tangential to the earth’s surface. It is evident that a
certain amount of shearing-movement must accompany the folding,
compression, or stretching affecting the different parts of the fold;
but so long as a bed is free to move as a whole (as in folding),
differential movement between the particles cannot take place to
any very great extent. The great shearing-movements which
have proved so effective in destroying original structures, may be
considered quite apart from the folding. They may have, and in
many cases certainly have, taken place after all folding-movement
in the immediate neighbourhood has ceased. The effect of the
nature of the folding is expressed simply in the angle at which the
original divisional planes of the rock are presented to the direction
of movement, which we assume to be a tangential pressure. The
original divisional planes in a sedimentary rock, planes of stratifica-
tion, are in fact surfaces between materials differing more or less in
physical properties, such as the coefficient of elasticity; and a force
applied from opposite sides of these surfaces must be resolved into
two components—one normal to the surface, tending to produce
compression, and one parallel to the surface, producing what in

12 MR. E, H. CUNNINGHAM-CRAIG ON [Feb. 1904,

geological parlance is called a shear. The angle at which the
surface lies to the force determines the magnitude of each com-
ponent. Thus, if a bed presents surfaces exactly normal to the
force, the shear-component is nil, and the only effect that can take
place is a compression of the bed which may cause a cleavage ;
while, if the bed lies at a lower angle to the force, the shear-
component is proportionately greater. Theoretically, I believe, the
shear-component should be greatest when the surface is inclined
at an angle of 45° to the force, but in actual fact we find that the
shearing is greatest in horizontal or almost horizontal folds. The
reason for this is not far to seek, as the flat-lving folds are
farthest from the main axis of folding, that is, they occur where the
greatest movement is possible. The effect of the folding now
becomes apparent: in tightly-packed vertical folding shear-move-
ments may be impossible, a cleavage of the finer bands of a rock
may be the only appreciable effect, and original structures may be
to a great extent preserved ; while, in a gently-inclined set of folds,
the shearing may be very great, original structures may be com-
pletely destroyed, and a high degree of schistosity induced parallel to
the original bedding. The greatest shearing-movements naturally
take place along those surfaces where there is the greatest difference
in physical properties between the beds on opposite sides of the
surface; and thus the shearing is concentrated, so to speak, in the
finer and softer beds against harder and more massive beds which
may not be greatly affected, thus causing what Mr. Lamplugh has
described in the Geological Survey Memoir upon the Isle of Man
(1903) as ‘ grit-band metamorphism.’ The shearing may have taken
place during the folding and the bending-over of the crests of the
folds away from the central axis of folding, but much of the shearing
has probably taken place at a slightly-later stage, while any sub-
sequent crust-movement may intensify the same effects. Should a
later movement, however, be checked by the presence of any massive
barrier, and should the ‘load’ or weight of superincumbeut material
be sufficient to prevent the development of a series of large folds,
puckering of the finer beds would be the result, and would be
shown by puckered folding, wrinkling of the finer and more elastic
bands, and finally by strain-slip cleavage in the laminee.

III. Consrructive MeramorpPHismM.

The effects of constructive metamorphism upon a rock depend on
(1) its chemical composition, which determines the possibility of
the formation of new minerals; and (2) the extent to which the
rock has been, or is being, affected by dynamic metamorphism.
It seems that the shearing and crushing processes, by mingling
more intimately the material from which the rock is built, afford
more favourable conditions for the segregation necessary in building
up a highly-crystalline rock under constructive metamorphism.
Thus, where original structures have been most completely broken
down, the constructive metamorphism can exert greater effect upon

Vol.60.] METAMORPHISM IN THE LOCH-LOMOND DISTRICT. 13

the crushed material, and the resulting rock may be much more
-highly-crystalline than a rock of similar composition which has
escaped the shearing and crushing to sume extent.

As the present state of any mass of rock de-
pends on the extent to which each of these pro-
cesses took effect, it is evident that the type
and nature of the folding become very
important factors in regional metamor-
phism. With these preliminary observations,
which sum up the conclusions arrived at by
other workers among metamorphic rocks, as well
as my own observations during seven years of
study of folded rocks, I may now proceed to a
description of the folding in the area in question.

S.E.
Aberfoil

LV. Narure oF THE FoLpine, AND STRATIGRAPHICAL
Rerations. (Fig. 1.)

The folding of the Leny Grits and Aberfoil
Slates, the groups lying nearest to the Highland
Border, is not very well seen, as a well-marked
cleavage has been produced in all the finer beds,
and has even affected the coarser grits to some
extent, with the result that the bedding is often
obscured. Where actual dips can be observed,
however, they are nearly always at high angles,
while the mapping out in detail of certain
grit-bands shows that the folding, though never
very deep, is somewhat tightly ‘packed.’ The
magnificent sections afforded by the slate-
quarries at Aberfoil and Luss confirm this obser-
vation. The cleavage is usually approximately
vertical, and often coincides with the bedding.

Passing north-westward and ascending in the
series, the cleavage gradually disappears, the finer
beds showing traces of it long after the more
massive beds have ceased to give any clear evi-
dence of such a deformation. A shear-structure
becomes more noticeable as the cleavage declines,
and the folding is easily recognizable. The rocks
belong to the Beinn-Ledi Group, and are chiefly
fine quartzose grits, becoming coarser in the
higher members. A compound syncline and
anticline are disclosed, formed of folds which
are practically isoclinal, with nearly vertical axial
planes. This flexuring of the massive Beinn-
Ledi Grits is a very important factor in the
metamorphism of the district, as the coarse upper
beds thrown into great vertical folds in the anticline seem to have
formed a relatively rigid barrier, against which the strata on either

Beinn Venue

Fig
Section from Aberfoil to Allt a'choinn. Length 10 Miles,
Loch Katrine

1.Green Beds. 2.Beinn-Ledi Group. 3,Aberfoil Slates. 4.Leny Grits. f. = Faults,

Cruinn Bheinn

14 MR. EH. H. CUNNINGHAM-CRAIG ON [Feb. 1904,

side have been strongly compressed. The anticline is well-marked
by the occurrence of many of the highest hills in the district, as, for
example, Beinn Ledi, Beinn Aan, Beinn Venue, and Beinn Bhreac,
which demonstrate the great resistance to denudation that these beds
present when vertically folded. A point to be noted in the belt of
country containing the anticline is that, although the folding is
isoclinal in the low ground, upon the hilltops the folds become
shallower and open out, thus showing a vertical gradation from
simple flexure to highly-compressed folding.

North-west of the anticline of Beinn-Ledi Grits comes one of the
most important structures in the area, a complex syncline of con-
siderable depth which brings down the overlying Green Beds. This
structure is traceable from Loch Lomond at Rowardennan, where
the trough is shallow, to the Trossachs, where the trough is most
clearly marked and deepest. The whole trough, which attains
a breadth of 14 miles in places, is marked by the outcrops
of the Green Beds, repeated several times—each outcrop being
essentially a minor synclinal fold. It was the mapping of these
beds, which form an easily recognizable horizon, that first made
clear the structure of the district. The folding is still distinctly
isoclinal in the lower ground, but less highly compressed towards
the hilltops; while, as we proceed north-westward, the axes of the
folds are seen to incline at successively lower angles to the south-
east. Thus, as regards the folding, but not the bedding, there
is a fairly well-marked fan-structure, which embraces the anticline
of the Beinn-Ledi Grits and the syncline of the Green Beds.

To the north of Loch Katrine this complicated syncline opens out
rapidly into a wide shallow basin, somewhat complicated by faulting
and overfolding at the south-western edge, where one lip of the basin,
as represented by the outcrop of the Green Beds, is repeated’ four
times in Glen Finglas. On the south-eastern margin of this basin
the folds of Green Beds ‘ pitch out’ towards the hilltops, and the
folding, though still sharp, becomes shallow: so that the outcrop is
represented by a few corrugated outliers, in which the folding,
though acute, is not of sufficient depth to affect the shape of the
outlier. Farther to the north-east, where the basin-shape becomes
less complicated, the folds open out still more, the strata being
flexured into large gentle domes and troughs, while each bed is
folded into small corrugated and right-angled folds; overfolds are
infrequent, and when present their axes incline to the north-west.

South-west of the Green-Bed outcrop in the great syncline the
folding is less well-marked and regular, but traces of the trough
can be made out on the western side of Loch Lomond.

The area, amounting to nearly one-third of the whole sheet, to
the north-west of the great syncline, does not afford good evidence
of folding on a large scale. ‘his is no doubt partly due to the fact
that recognizable horizons cannot be followed throughout the area,
but it is also certain that through the greater part of this area
there is little or none of the regular compressed folding charac-
teristic of the belt of country nearer to the Highland Boundary.

Vol. 60.) METAMORPHISM IN THE LOCH-LOMOND DISTRICT. 15

The north-western margin of the trough gives evidence of low-lying

_ folds which are gradually losing their sharpness, and the rocks

emerging from beneath the trough exhibit this to an even greater
extent, so that very rapidly all trace of regular folding is lost.
Rolling and puckered folding of no great depth is the rule, and con-
tinues north-westward to the neighbourhood of Ardlui at the head
of Loch Lomond, where evidence of more regtlar folding, the margin
of the great Highland fan-structure to the north, begins to appear.

The structure, then, from the great trough to the north-western
corner of the sheet, is practically horizontal, the minor flexuring
and crumpling of the beds being of little account, and the surtace
is occupied by rocks of the Beinn-Ledi Group. This fact was only
arrived at by careful examination of a great part of the area, and
the identification of outliers of the coarsest bed of Beinn-Ledi Grit
at various points : as, for example, An Garadh north of Loch Katrine,
Beinn Lomond, and Beinn Bhreae and Tullich Hill in Dumbartonshire.
Still more important were the recognition of an outlier of the Green
Beds on Cruinn Bheinn, north of Loch Katrine, at a distance of
2 miles from the margin of the great trough, and the identification
of the Green Beds again at Ardlui, in a very highly-altered state.

These points having established the stratigraphy and the general
structure by actual mapping, we are now enabled to consider the
bearing of the structure upon the general and progressive meta-
morphism of the area.

VY. PrerroGrRapsicaL DESCRIPTIONS.

A large number of microscope-slides from the area have been
examined, and in the following descriptions selected slides and
specimens from different parts of the area form the basis of the
account of the various phases of metamorphism to be considered ; a
series collected from the western shore of Loch Lomond to
illustrate the progressive metamorphism, for the Explanation of
Sheet 38 of the l-inch Geological Survey Map of Scotland, is.
included.*

(a) The Leny-Grit Group.

The Leny Grits appear to differ very little in character, from
whatever part of the area they are collected. They consist
essentially of pebbles of quartz and felspar (mostly oligoclase)
in a fine matrix which is usually more or less chloritic, and
partakes more of the nature of an ordinary clastic than a crys-
talline rock. The matrix exhibits a distinct schistosity; but
the pebbles, especially where the grit is coarse, are little affected :
strain-shadows in the quartz and peripheral granulation are often
the only signs of dynamic metamorphism. The smaller pebbles,
however, may be completely granulitized, or may show ‘tails’

* I am indebted to Mr. J. D. Falconer, of the University of Edinburgh, for
very kindly preparing the microphotographs which have been used to illustrate.
this paper.

16 MR. E, H. CUNNINGHAM-CRAIG ON. ~=——s[ Feb. 1904,

of granulitic material drawn out in the direction of schistosity.
The felspar-pebbles are either fractured or apparently unaffected,
but are often much decomposed. The matrix is also cloudy and
decomposed; it consists of granulitic quartz, a little chlorite and
sericitic mica, and iron-ores, and it has never attacked the pebbles,
even where they are somewhat ragged in outline. A slide of
coarse grit’ (8983, PL II, fig. 1) from Craignahuillie, south of
Luss, is a fair instance of the state of metamorphism attained
in this group. A finer grit from Creachan Hill, south of Luss,
shows the pebbles with ragged ends, and the complete granuli-
tization of some of them. An alkali-felspar (much decomposed)
is present in this rock, and a small patch of microcline has been
preserved in a quartz-pebble. The matrix is chloritic and sericitic.
The preservation of the microcline by being included in a fragment
of quartz is significant, as suggesting that alkali-felspar may have
been present in greater quantity in the original rock but has been
destroyed in the dynamic metamorphism, giving rise to the sericitic
mica of the matrix. Clastic micas may be occasionally detected
in the finer grits. These beds occur, as has been stated, in highly-
compressed vertical folds, and it is evident that the phase of
dynamic metamorphism is not very high, while constructive meta-
morphism can hardly be said to have commenced, its only effects
being the meagre development of sericitic mica and chlorite, which
may also be partly of clastic origin.

(b) The Aberfoil-Slate Group.

Passing north-westward, and ascending in the series, we come to
the Aberfoil Slates and slaty grits, a series of fine sediments which
are much more liable to dynamic alteration from their comparative
softness, and also to constructive metamorphism from their more
complex composition. A section of slate (2567), from the head of
Glen Fruin, shows a considerable development of more or less
indeterminable micaceous minerals, chiefly sericitic mica and
chlorite, along the cleavage-planes, which cross the bedding at
a high angle. The bedding is marked by the presence of minute
aggregates of quartz, and one distinct pebble is noticeable. How
much of the micaceous constituents can be said to be due to
constructive metamorphism it is impossible to say, but there has
evidently been no crystallization on more than a very minute
scale; the rock has been deformed, and the constituents rearranged
by dynamic metamorphism, but the constructive metamorphism is
still at a minimum.

Another section (2568) from Rowmore, Garelochhead, shows an
originally fine gritty rock assuming the character of a phyllite.
Much drawn-out phacoids of quartz and a little plagioclase-felspar
show that the rock was originally gritty, but a good deal of the felspar
has probably been destroyed, and the development of micaceous

1 The numbers are those of the slides in the collection of the Geological
Survey of Scotland.

Vol. 60. | METAMORPHISM IN THE LOCH-LOMOND DISTRICT. i ly

minerals serves to class the rock as a phyllite. The developing
schistosity 1 is along the planes of cleavage. Reconstruction of the
matrix under constructive metamorphism i is at a very low phase.

(c) The Bemn-Ledi Group.

Still proceeding north-westward, we reach the Beinn-Ledi Group
of grits, schists, and greywackés. These rocks, where folded into a
vertical isocline, have as a rule suffered little from shearing-stresses,
especially where coarse and gritty in texture and highly siliceous in
composition ; the finer and more felspathic bands, on the other hand,
present a more favourable field for the action of metamorphic
processes, and are accordingly more greatly atfected.

A specimen (3679) taken from the Trossachs, a quarter of a mile
east of Loch Katrine, shows the state of a fairly fine grit in a
vertically-folded area. The matrix is mainly composed of granulitic
quartz, with some cloudy indeterminate material and sericitic mica.
The pebbles are chiefly of quartz, though a number of small striated
felspars are visible. ‘The felspar-pebbles appear to have been frac-
tured or crushed more than the quartz, and there is a little calcite
present—an important point, which will be referred to later. There
is very little sign of shearing or orientation of the pebbles; they
lie at all angles to the planes of schistosity, but show peripheral
eranulitization and a tendency to merge into the matrix. There
iss no recrystallization of the matrix to obscure the original
planes of bedding, which coincide with the schistosity ; but much
of the granulitization may possibly be due to incipient thermo-
metamorphism. On the whole, the rock shows fewer signs of
dynamic metamorphism than the last, and very little constructive
metamorphism.

To examine the effects of metamorphism upon the rocks at
about this horizon—high up in the Beinn-Ledi Group,—a series of
specimens was collected from the western shore of Loch Lomond,
all being taken at approximately the same level, and being (as nearly
as it was possible to ascertain) from the same horizon. It has
been mentioned before that in this area, west of Loch Lomond, rocks
of the Beinn-Ledi Group occupy the surface from Luss to Ardlui.
The next specimen taken comes from Rudha Mor, beyond the belt
of vertical folding and where the folds are rapidly becoming flatter
and of small amplitude. This specimen (8984, Pl. III, figs. 1 & 2) —
shows, as might be expected, a much advanced stage in ‘the meta-
morphism. It has been a coarse siliceous grit, but now, although
the larger pebbles are still distinct, the development of planes of
schistosity has cut up the rock into elongated phacoids, with
micaceous folia separating them. Under the microscope the matrix
is seen to consist of granulitic quartz, sericitic mica, biotite, and a
few grains of sphene; the pebbles are of quartz and decomposed
felspar. The quartz-pebbles are sometimes completely granulitized
and merging into the matrix; others are only peripherally granu-
litized, but show strain-shadows and drawn-out ‘tails’ of granulitic

Q.J.G.8. No. 237. C

18 MR. E. H. CUNNINGHAM-CRAIG ON { Feb. 1904,

quartz. The felspar-pebbles are almost completely destroyed and
decomposed, and are associated with the micaceous films. The
biotite is in well-developed flakes, lying at all angles to the
schistosity, but it seldom pierces the quartz-granules of the matrix,
showing that the quartz has not been recrystallized to any great
extent. The biotite is the first clearly authigenic mineral to be
observed in these rocks, and has evidently been developed by
constructive metamorphism after the shearing-movements which
produced the schistosity had ceased.

From this point onward, as we recede from the Highland
Border, allothigenic minerals decrease in number, while there is a
corresponding increase in authigenic constituents. [am inclined to
regard the constructive metamorphism which has affected the last-
described specimen as probably a normal thermometamorphism. In
the specimens that follow we find effects, increasing to the northward,
of a different type of constructive metamorphism, the nature of
which will be discussed later.

The next specimen (8985) was collected at Rudha Dubh,
13 miles to the north-north-west. It has probably been a finer-
grained rock originally, and occurring in a locality where the beds
are lying at a low angle, schistosity has reached a much higher
stage. The rock consists of irregular grains of quartz and plagio-
clase, with folia of sericitic mica, chlorite, and green or chloritized
biotite, some calcite (probably from decomposed plagioclase), and a
few grians of sphene and magnetite. Pebbles have disappeared, but
the arrangement of lenticular aggregates of granulitic quartz suggests
that pebbles may once have been present: they may be called the
‘chosts’ of clastic grains. The quartz and felspar do not appear to
have been recrystallized to any extent; but the micas, chlorite, and
possibly sphene, are authigenic. The presence of calcite, the deve-
lopment of chlorite, and the chloritization of biotite might be
attributed to weathering. I am inclined to regard them, however,
as the first stages in the special type of constructive metamorphism,
which, from this point to the head of the loch, becomes increasingly
conspicuous.

A rock (8986) from the shore opposite Tarbet Isle, where the
strata and folding are practically horizontal, carries the meta-
morphism a stage further. ‘This is a siliceous but conspicuously-
schistose rock, with a considerable development of white mica,
which gives it a flaser-structure. Only the ‘ghosts’ or suggestions
of original pebbles are to be seen, but their shape and size point to
the rock having been originally coarser in grain than the last.
Fragments of both oligoclase and alkali-felspar are present, although
they may be in part recrystallized. The quartz is certainly
becoming authigenic by recrystallization into a larger mosaic,
the grains of which not infrequently include flakes of biotite.
Some calcite and magnetite are also present.

At this stage, it may be as well to glance at the evidence from the
area to the eastward of the loch, and approximately on the same iine

Vol.60.] METAMORPHISM IN THE LOCH-LOMOND DISTRICT. 19

of strike, both the flexuring and the strata striking from north-east
to south-west. The rocks which emerge from below the great
syncline differ very greatly, as has already been stated, from the
same rocks to the south-eastward of the syncline. The area
south of Loch Katrine illustrates this admirably. In the rolling
and crumpled folds north-west of the trough grit-beds are fre-
quently noticed, but they can never be traced far ; the normal type is
a glistening mica-schist, which apparently becomes more micaceous,
and certainly more fissile, to the north-westward, as gritty bands
become less and less frequent. The rocks invariably split along
the planes of foliation, and thus present micaceous surfaces giving
all the appearance of a phyllite; but a careful examination shows
that to call them ‘ phyllites’ would misrepresent their composition.
If a good cross-fracture (a difficult thing to obtain) is examined, it
is seen that these schists are made up of folia or elongated phacoids
composed chiefly of quartz, separated by mere films of micaceous
minerals along which the rock naturally fractures. Thus the
quantity of the micas present is apt to be overestimated at first.
In the phacoids remains of allothigenic structures may often be
observed, long after all traces of a regular bed of grit have been lost.
A specimen (3681) from the shore of Loch Katrine, three-quarters
of a mile south-south-east of Stronachlachar Hotel, is a characteristic
example of this type of mica-schist. No grits have been recognized
in the locality. The specimen consists ot alternating folia of granulitic
quartz and micaceous minerals, chlorite, white mica, and a little
biotite ; the quartz has partly recrystallized, and contains the micas.
A few large allothigenic quartzes, however, are still present, but
they are almost entirely granulitized ; and there are also several
much-iractured and decomposed remnants of plagioclase-pebbles.
Thus it is seen that, even in a locality where the rocks are typically
mica-schists, evidence of their having been grits may be obtained,
and that the grits were fairly coarse in grain may be deduced from
the size of the remnants of pebbles.

Returning to the shore-section on Loch Lomond, we find at
Inveruglas a rock (8987: Pl. II, fig. 2) in which all allothigenic
minerals have disappeared, while distinct evidence of a new and
remarkable type of constructive metamorphism, to which allusion
has been made above, is obtained. The rock consists of quartz,
recrystallized, and often leached out into veinlets following the
foliation-planes, felspar in a few small decomposed fragments, and
well-developed micas, muscovite and a little biotite, which are both
included in the recrystallized quartz. Veins of calcite point to the
removal of lime from crushed and decomposed plagioclase. But
the most important point is the development of a few small clear
blebs of albite, which are chiefly associated with the micaceous folia.
The rock shows the first stage in the building-np of an albite-
gneiss. From this point onward it is impossible to note increase
in the dynamic metamorphism, as there are no clastic structures by
the destruction of which such metamorphism can be measured ; it

c2

20 MR. E. H. CUNNINGHAM-CRAIG ON [ Feb. 1904,

is evident, however, that in the area north-west of Inveruglas the
dynamic metamorphism does not diminish, and it may have increased.
The constructive metamorphism increases rapidly.

Three specimens from the eastern side of the loch at Inversnaid
supply the next link in the chain.

The first of these (8999, fig. 2, below) is a very siliceous rock, con-
sisting chiefly of folia of granulitic quartz with biotite, chloritized
biotite, albite, and magnetite. The quartz is all recrystallized into
a coarse mosaic, and the albites are larger and more distinct than in
the last specimen ; there is also a tendency for the albite-grains to

Fig, 2.—Slide No. 8999. [Seen under a 1-inch objective. |

[A highly-crystalline gneiss from Inversnaid, showing the first appearance of
small authigenic albites and the leaching-out of quartz into lenticles.
Muscovite and biotite are also present. |

be concentrated in folia. In a more micaceous specimen (9000),
chlorite and muscovite are very abundant, being associated both
with folia of quartz and with the authigenic albites; but the
albites are hardly, if at all, more abundant than in the more
siliceous specimen. ‘The third specimen (3680) is composed chief

of flakes of chlorite and muscovite lying at all angles to the bedding,
with interstitial quartz and a few large albites. Thus, in a rock
which most closely resembles a phyllite or slate in composition, the
development of albite is little greater than in a highly-quartzose
gneiss evidently formed from a grit. The albites in these specimens
show little or no trace of idiomorphic outlines: they appear as rounded
or elongated grains. Polysynthetic twinning is never observed ;

Vol.60.| | METAMORPHISM IN THE LOCH-LOMOND DISTRICT. 21

but the albites contain numerous inclusions, chiefly of magnetite,
_ which are sometimes so abundant as to show the direction of
original foliation or bedding, as in the last specimen. The
micaceous minerals, however, are never included in the albites.

The next specimen, from Creag an Ardain (8988), shows a
still further advance: the albites are larger and more conspicuous,
and are aggregated more distinctly into folia or lenticles, while the
quartz is also to a great extent segregated out into lenticles. The
albites are associated with a large quantity of chlorite and some
white mica, while biotite is no longer present.

In the next slide (8989), from Ardvoirlich, the albites are even
more conspicuous, and the rock may be described as a typical
albite-gneiss. The association of the albite with chlorite is again
to be noted, and the inclusion of quartz, magnetite, and epidote in
the albites. The epidote is important, its occurrence pointing to the
presence of lime, derived probably from destroyed plagioclase.

Rudha Ban, from which the next specimen (8990, Pl. IV, figs. 1
& 2) is taken, has long been a famous locality for albite-gneisses.
All the rocks in this neighbourhood contain a large percentage of
albite, and when the grains of this mineral are large they weather-
out like the pebbles in a grit, giving almost a clastic appearance to
highly-erystalline rocks. The slide shows very clearly the segre-
gation of the materials into folia, quartzose lenticles alternating
with those rich in albite. The quartzose lenticles often attain a
large size, and appear as discontinuous veinlets in the matrix; but
it is quite evident that these veinlets belong essentially to the rocks
in which they occur, and the silica has not been introduced from
elsewhere.

Another slide from farther north, at Stuckindroin (8991), presents
the same characteristics in a rock of more siliceous composition :
albite and chlorite, though present in considerable quantity, being
less conspicuous than quartz and muscovite. A few small garnets
are occasionally present in these rocks, but they are comparatively
rare, and never attain a sufficient size to be conspicuous in hand-
specimens. Calcite-veins are often fairly numerous, biotite is
almost, if not entirely, absent, while chlorite is abundant.

On the whole, the rocks in this belt of country, from Inveruglas
to Stuckindroin, are remarkably constant in character; they are
all albite-gneisses produced by a constructive meta-
morphism, which reaches its maximum about the neighbour-
hood of Ardvoirlich and Rudha Ban, and does not appear to
decrease to the northward. Two points are worthy of attention:
(1) that the albites show a tendency to include all the other
minerals, with the exception of micas and chlorite; and (2) that
the albites give no indications of having been affected by movement
of any kind—in fact, the lines of inclusions not infrequently show
the minute puckering and folding which was the latest movement
to affect the rocks: thus proving that the albites have developed
since the movement ceased.

bo
bo

MR. E. H. CUNNINGHAM-CRAIG ON [ Feb. 1904,

(d) The Green Beds.

The progressive metamorphism of the Green Beds cannot be
traced in this area in detail, as there are no exposures of these
strata between Beinn Lomond and Ardlui. It is not necessary to
describe now the alteration that they have undergone, a description
which I hope to give in a future communication. It will be sufficient
to state here that the metamorphism of these well-known rocks
bears out the conclusions as to progressive metamorphism arrived
at after examination of the rocks of the Beinn-Ledi Group. On
the southern slopes of Beinn Lomond they are epidotic and chloritic
grits ; at Ardlui they are hornblende-schists, nct easy to distinguish
from hornblende-schists of igneous origin.

« VI. CnhemicaL ANALYSES.

The stratigraphicai relations of the albite-gneisses having been
proved by a study of the structure of the district, and by the identi-
fication of the Green Beds at Ardlui, we are impelled to the conclusion
that they have been formed by the action of dynamic and construc-
tive metamorphism from the Beinn-Ledi Grits, unless we are to
assume a change in lithological character and chemical composition
in the rocks of the Beinn-Ledi Group when traced north-westward.
Chemical analysis was necessary to prove whether or not such a
change existed. I was inclined to disbelieve in such a change,
but I found, after arriving at the conclusion stated above, that
Continental geologists favoured the view that albite-gneisses of
similar character had been formed by the metamorphism of phyllites
rather than grits.

Mr. Teall,in the Appendix to the Survey Memoir on the ‘ Geology
of Cowal’ (1897) p. 297, refers to the occurrence of rocks con-
taining authigenic albite in the northern border of the central zone
of the Eastern Alps. These rocks were described by A. Boehm,"
who defined the type as transitional between the old crystalline
schists and the true phyllites. Mr. Teall also refers to the albite-
phyllites of Saxony,” and of the Green Mountains of Massachusetts.°
In all these instances the association of minerals appears to be
similar: white mica, chlorite, and folia of quartz accompanying the
albite.

The suggestion is made in some, if not all, of these cases that the
albite-gneisses have been formed from phyllites, but the descriptions,
especially in the case of the Green Mountains, hardly seem to uphold
this idea. Prof. Wolff, in his description of these schists or gneisses

* «Ueber die Gesteine des Wechsels ’ Tschermak’s Min. u. Petr. Mitth. n. s.
vol. v (1883) p. 197.

* K. Dalmer, ‘ Erlaiiterungen zur geologischen Specialkarte des Konigreichs
Sachsen—Section Léssnitz’ 1881.

* Monogr. U.S. Geol. Surv. vol. xxiii (1894).

Vol. 60.] | METAMORPHISM -IN THE LOCH-LOMOND DISTRICT. 23

in Hoosac Mountain,} calls attention to the strings and lenticles
of quartz developed along the bedding-planes of the albite-schist,
as evidence of a higher percentage of silica in the rock than would
be met with in a true phyllite.

~ In the Survey Memoir on the ‘Geology of Cowal,’ also, Mr. C. T.
Clough suggests the possibility of the development of albite-gneisses
from phyllites; and two analyses (op. cit. p. 39) were made from
selected specimens—one of phyllite, the other of albite-gneiss, to
see whether these rocks were similar in chemical composition.
These analyses are tabulated below.

FE ELE. IV

Per pent Per cent. Per cent. Per cent.
iE ne 43°3 63°4 69°11 77-22
_ ee ge 1-2 trace 0°83 0°59
a 181 15°78 10°07
areal \ 136 6-7 6-49 4-02
> ee not estimated not est. 0-24 0°30
ES 05 0-9 1°34 1:10
__- | Seer 38 19 1°95 Ei7
_ See 46 5p 397 2-69
_ eee 18 an 2-49 2-65
i See ae | 9.2 1-41 0°36
ae a = 0-39 0-32
> See not estimated not est. O25 O14

_ 1+ aes not estimated not est.’ O-14 at
1 eee 99°5 100:2 100°39 100°59

As the iron in I & IT was estimated as Fe,O,, and FeO was not estimated,
the total iron in III & IV is given as Fe,O, for the sake of comparison.

The percentages 4:5 & 28 in I & II respectively were ‘loss on ignition,’ and
are given as H,O & CO, bracketted ; this Joss may aiso include a percentage of
sulphur.

I. Green phyllite from Blairmore (Cowal), \ ATi ,
II. Albite-schist from Stuck Burn (Cowal), analysed by Mr. J.J. H. Teail.

III. Albite-gneiss from Rudha Ban, X 17
IV. Schistose grit from Rudha Dubh, i ered ate Sen epee

For the ‘ Explanation of Sheet 38’ by the Geological Survey,
two analyses have also been made by Dr. W. Pollard: one of a typical
albite-gneiss from Rudha Ban; the other of the coarsest and most
siliceous grit that could be obtained in the section on the western
shore of Loch Lomond, at Rudha Dubh. It must be mentioned
here that a finer-grained, less siliceous, and more micaceous speci-
men of schistose grit could easily have been selected; but in order
that there should be no forcing of the evidence to agree with the
conclusions to which I had come previously, I determined to select
the very coarsest and most siliceous grit that I could find—in fact,
what I may call an extreme case of siliceous grit, as compared with
an average specimen of albite-gneiss.

? Monogr. U.S. Geol. Surv. vol. xxiii (1894) pp. 59 et segq.

24 MR. E. H, CUNNINGHAM-CRAIG ON [Feb. rgo4,

In the foregoing table (p. 23) these analyses are set forth. It will
be seen at a glance that there is a very close resemblance between
the albite-gneiss from Cowal (II) and the albite-gneiss from Loch
Lomond (III), not only in the actual percentages, but in the ratios
of one base to another. I may here remark that the discrepancy
between the ratios of potash to soda in the two rocks may be more
apparent than real, as Dr. Pollard made three separate estimations
of the alkalis in III from different samples of the same specimen,
checking his results by an estimation of the silica, and so proving
that the analyses were absolutely correct. These analyses gave
somewhat different results, as follows :—

a. bh,
KIO) foe ae. 3°88 397 aon
INO ee ae 2°38 2°49 aa) 1

Result 6 was obtained from the largest amount of material, and
is accordingly. given in the table, but it will be seen that ¢ gives a
ratio practically the same as the ratio of potash to sodain II. If
the mean of the three analyses be taken, we get 3°70 per cent.
of potash to 3 of soda, a ratio not differing very greatly from
that in II.

The next point brought out by these analyses is the great
dissimilarity between the phy [lite (1) and either of the albite-gneisses
(II & III). The low percentage of silica, lime, and soda, and the
high percentage of alumina, iron, magnesia, and potash make this
clear at once; while if the ratios, for example, of potash to soda, be
taken, the difference becomes even more conspicuous. It is evident
that a phyllite of such composition could not possibly form an
albite-gneiss.

When we turn to the analysis of the schistose grit (LV), it does not
seem at first to resemble those of the albite-gneisses very closely,
but it must be remembered that this rock was selected as being the
most siliceous that could be obtained. Consequently, we find a very
high percentage of silica,and the other constituents are reduced in
proportion. ‘aking the ratios of one constituent to another, the
resemblance between the grit and the albite-gneiss becomes very
striking: thus the ratio of ‘alumina to lime or magnesia in the grit
approximates fairly well to the ratio of the same constituents in
the albite-gneisses, while the ratio of potash to soda is exactly
the same as in the albite-gneiss specimen from Cowal. From
these facts it is evident that an albite-gneiss could be formed even
from a highly-siliceous grit.

VII. Tue Zones or ProcresstvE METAMORPHISM.

The sketch-map (fig. 3, p. 25) shows approximately the different
zones in the metamorphism of the Beinn-Ledi Group: first that in

Vol.60.] METAMORPHISM IN THE LOCH-LOMOND DISTRICT. 25

which grits predominate, almost every rock being a fine or acoarse grit ;
then the zone of mica-schists,.in which a few of the coarser grit-bands
still survive owing to their resistance to dynamic metamorphism ;
then the zone of mica-schists, composed entirely of authigenic minerals ;
and finally the zone of albite-gneiss. To the south-west, in Cowal,
the boundaries of these zones cross, a circumstance which makes

the study of the meta-

Fig. 3.—Sketch-map of the Loch-Lomond morphism much more
district, to illustrate the zones of meta- difficult, as schistose grits
morphism. (Approaimate scale: Giniles MOY be found stratified
= inch.) with albite-gneisses : the

former representing beds

which have resisted suc-
cessfully the dynamic
metamorphism, and con-
sequently to a_ great
extent the constructive
metamorphism ; while the
latter are the beds which
have succumbed to the
dynamic, and so fallen

x an easy prey to the con-

a= eee structive, metamorphism.
= The crossing of the boun-

daries of these meta-
morphic zones probably
takes place also north of

Glen Gyle: it is demon-

strative proof that the

albite- gneisses are not

a stratigraphical group.

The Loch-Lomond dis-

trict is remarkable in

te ee. ; ing practically
[The asterisks indicate localities where speci- being practical!) free

mens of the rocks described in this paper from _ such contusing
were obtained. | complications.

ICA-SCHIS
WITH

VIII. Conract-MrramorpuismM.

One other phase of metamorphism in the district must be recorded
briefly, and that is contact-metamorphism. In the albite-gneiss
area are numerous intrusions of what are called the ‘newer granites
and diorites’; that is to say, a series of intrusions well-known
in the Highlands, and probably in the main of Old-Red-Sandstone
age, which have been intruded after the regional metamorphism.
The effect of these intrusions on the albite-gneisses is remarkable.
On approaching such an intrusion as the Beinn-Vane (Mheadhoin)
diorite or the Inversnaid hyperite, the albites are seen to assume a
red coloration, due to the oxidation of the magnetite-inclusions, while

26 MR, E, H. CUNNINGHAM-CRAIG ON [Feb. 1904,

chlorite begins to give place to biotite. Under the microscope the
albite soon appears cloudy and decomposed, and finally, as the junc-
tion is approached, vanishes altogether, while biotite and contact-
minerals make their appearance, and may become very conspicuous,
in the ‘ hornfelsed’ zone near the contact. Dr. Flett has identified
cordierite in the hornfels surrounding the Inversnaid hyperite.

A specimen (8992, Pl. V, figs. 1 & 2), which shows very clearly
what happens to the albite-gneiss witbin an aureole of contact-
metamorphism, is taken from the railway-cutting north of Ardlui,
at a distance of about 1} miles from the great Meall-Garabal
complex described by Messrs. Teall & Dakyns.! The hand-specimen
resembles very closely the normal albite-gneiss with quartz-veinlets,
but the colour is darker and the rock generally less fissile. Under
the microscope it is seen that albite and chlorite have almost
entirely disappeared, the former being replaced chiefly by aggregates
of white mica, in which a soda-mica is probably present, while
sporadically-developed flakes of biotite replace the sheaves of
chlorite. In the siliceous folia the development of biotite 1s more
regular. A few rather decomposed blebs of albite can still be recog-
nized in some parts of the slide, and in these eases a little chlorite
is generally present also. More significant of the contact-action
are groups of andalusite-granules which occur among the feathery
masses of white mica.”

IX. Nature oF THE ALBITE-GNEIss METAMORPHISM.

It is not my intention to go more fully into the contact-action of
these igneous masses. Mr. Clough, in the Survey Memoir on the
‘Geology of Cowal,’ has described the contact-metamorphism on the
Other side of the same petrographical complex. or my purpose,
sufficient has been said to show the effects of a thermal contact on
the rocks which have been previously altered to albite-gneisses.
This leads naturally to the question as to what is the kind of meta-
morphism to which the production of these albite-gneisses is to be
attributed. On this question I have to offer a suggestion, which must
for the present remain more theoretical than the other conclusions set
forward in this paper. I have had the experience of tracing the same
rocks of the Beinn-Ledi Group through a progressive metamorphism
in other districts, and more especially in the district of Aberfeldy,
where they may be traced from not very greatly-altered schistose
grits into highly-crystalline muscovite-biotite-schists or gneisses
with a considerable number of large and well-developed garnets.
The dynamic metamorphism is much the same as in the Loch-

* Quart. Journ. Geol. Soe. vol. xlviii (1892) p. 104.

* In the andalusite-biotite hornfels near the contact with the Glen-Fine
granite, described by Mr. Clough, in the Survey Memoir on the ‘ Geology of
Cowal’ (1897) p. 98, a quantity of albite is still present, but it has probably
been recrystallized: idiomorphic outlines are not uncommon, and twinning is
frequent.

&

AS)

Vol. 60. | METAMORPHISM IN THE LOCH-LOMOND DISTRICT. 7

t

Lomond district, but the constructive metamorphism is very
different, for nothing like the albite-gneisses has been observed in
the Aberfeldy district. If albite be present at all, it is in small
water-clear granules mixed with the granulitic quartz-folia.
Chlorite is absent, and in its place occur folia of intergrown
muscovite and biotite with a considerable development of garnet.
We have been accustomed to consider this type of alteration as due
to an essentially-thermal metamorphism. I venture to suggest
that the albite-gneisses are due to a hydrothermal
type of metamorphism. The absence, or presence only in very
small number, of garnets; the leaching-out of the siliceous and
felspathic materials into separate folia ; the fact that the albites only
begin to develop after the plagioclase has been destroyed, and after
the removal of lime as carbonate (of which there is evidence) ; and
the association of the albites with a hydrated mineral, chlorite, all
point to this conclusion. The fact that a thermal contact at once
destroys the development of albite adds confirmatory evidence.
The view that we are dealing with a hydrothermal type of con-
structive metamorphism is not inconsistent with the observations
of Tschermak and other Continental geologists, who found that
albite-gneisses formed a transitional stage between slightly and
highly-altered sediments.

X. ReCAPITULATION.

To recapituiate, we are dealing in the Loch-Lomond district
with a progressive metamorphism, each stage of which can be
accurately determined, and each process of which can be studied, as
a rule, without confusing its effects with those due to another
process. In the first place, we saw rocks from the Leny-Grit Group
and Aberfoil-Slate Group yielding evidence of dynamic metamorphism
not in a high degree, and of practically no constructive meta-
morphism whatever. Then, entering a higher stratigraphical
horizon, the Beinn-Ledi Group, we saw the dynamic metamorphism
increasing, and at Rudha Mor the beginning of a constructive
metamorphism of the thermal type, which was quickly superseded
by a constructive metamorphism probably of hydrothermal type,
under which, combined with, or preceded by, the increasing dynamic
metamorphism, the rocks rapidly became more highly crystalline
until all clastic structures had been obliterated. The segregation of
like materials into folia, the total recrystallization, and the genesis
of new mineral-groupings, resulted finally in the production of
coarsely-crystalline albite-gneisses from a series of fine and coarse
siliceous and felspathic grits. Finally, we have seen the effects
of contact with plutonic igneous masses, in the obliteration of
many of the results produced by the hydrothermal constructive
metamorphism,

28 MR. E. H, CUNNINGHAM-CRAIG ON [ Feb. 1904,

EXPLANATION OF PLATES II-V.

[With the exception of fig. 2 in Pl. V, photographed under a 32-inch objective,
all the slides are represented as viewed under a 1-inch objective. |

Puiate II.

Fig. 1 (8983). Schistose grit from Craignahuillie, which shows the breaking-
down of a large quartz-pebble in a schistose but non-crystalline
matrix. (See p. 16.)

2 (8987). A highly-quartzose schist from Inyeruglas, in which allothigenie
structures have been completely destroyed. It shows recrystallized
quartz and authigenic muscovite. A vein of calcite, derived from
crushed felspar, is seen on the right. (See p. 19.)

Prats IIT.

Fig. 1 (8984). Schistose grit from Rudha Mor, showing a large quartz-pebble,
partly granulitized, in a matrix rich in authigenic biotite.
2. The same under crossed nicols. (See p. 17.)

Puate LV.

Fig. 1 (8990). A typical albite-gneiss from Rudha Ban, very highly crystalline.
It contains albite, quartz (recrystallized in lenticles), chlorite (abun-
dant), muscovite, and pyrites. (See p. 21.)
2. The same under crossed nicols.

PuAatTE VY.

Fig. 1 (8992). This shows the effects of contact-metamorphism on an albite-
gneiss from Ardlui. There is a finely-crystalline development of
biotite and white mica, with quartz recrystallized in lenticles, but
albite and chlorite are absent. (See p. 26.)

2. The same, more highiy magnified: showing the granular development of
andalusite.

Discussion.

Mr. H. M. Capertr said that the completion of this map interested
him greatly, as it had been some 25 years in progress and was
happily out at last, to the great advantage of Scottish geologists,
who had awaited it for nearly a generation. He had worked on
the western part some 18 or 19 years ago, and the Author had
worked out the structure in much greater detail and with the aid
of the microscope, which was not so much in vogue when he was
there, the consequence being that the Author had greatly modified
part of his (the speaker’s) results. He was glad of this, as geology
was, and should be, a progressive science. He would like the Author
to say what became of the limestones that occurred among the
slates south of Luss, as these passed northward into the more
highly-metamorphosed area ; also what, if any, was the nature of
the contact-metamorphism round the granite and diorite-intrusions
north of Arrochar ; and further, whether the Author knew the source
of the ilmenite which occurred in considerable quantities in that
locality.

The Coarrman (Sir Ancurpatp Gerxigz) spoke of the early work of
the Geological Survey in the Loch-Lomond district, and the difficulty
that was experienced there in making out the order of succession of

- QUART. JOURN. GEOL. Soc., VoL. LX, PL. II.

J. D. F., Photomicr. Bemrose Ltd., Collo.

SCHISTOSE GRIT AND QuUARTZOSE ScHiSsT.

QuarT. JouRN. GEOL. Soc., VoL. LX, PL. III.

Fic 1.

Fic. 2.

Codlo.

J. D. F., Photomicr.

Benirose Lid.,

SCHISTOSE GRIT FROM RUDHA Mor.

Quart. JOURN. GEOL. Soc., VoL. LX, PL. IV.

J. D. F., Photomicr. Bemrose Ltd., Collo.

ALBITE-GNEISS FROM RUDHA BAN.

Need ae =
ae AT

i. <r ore

Quart. Journ. GEOL. Soc., VoL. LX, PL. V

J. D. F., Photomicr. Bemrose Litd., Coilo.

CONTACT-METAMORPHOSED ALBITE-GNEISS FROM ARDLUI.

1. 60.] METAMORPHISM IN THE LOCH-LOMOND DISTRICT. 29
the crystalline schists and less-altered sedimentary rocks. It was felt
that, until a much larger area of the Highlands had been mapped and
some more distinctive stratigraphical horizons had been traced, no
definite conclusions on the subject could be drawn. The fresh in-
formation required had been now supplied by the work of the Author.
Using the horizon of the ‘Green Beds’ as the key to the structure of
the ground, he had shown that the apparently-enormous thickness of
the rocks could be satisfactorily reduced to much more reasonable
proportions, and that folding on a great: scale had affected the whole
region. With the microscope as an adjunct to his field-work, the
Author had been able to trace an interesting series of metamorphic
changes, from the coarse grits of the Highland Border into highly-
crystalline albite-gneisses. He was about to proceed to the West
Indies to undertake some important duties there, and the speaker
was sure that the Society would heartily wish him all success in
that distant region, and would hope to welcome him on his return
with a fresh harvest of geclogical results.

The AvurHor, in answer to Mr. Cadell, said that the limestone in
the Aberfoil Slates was not the same as the limestone occurring to
the north, which was the Loch-Tay Limestone, at a much higher
horizon. The contact-metamorphism had not been examined in
detail, nor had the source of the ilmenite in these schists been
ascertained. As the Chairman had said, it was the mapping of the
‘Green Beds’ which had explained the structure of the district and
indicated the thickness of the rocks. He thanked the Chairman
for his remarks, and the Fellows for the manner in which the paper
had been received.

30 MR. H. DYKE ACLAND ON A [Feb.:1904,

3. On a New Cave on the Eastern Sipe of Grprattar. By
Henry Dyxe Actanp, Esq., F.G.S. (Read November 4th,

1903.)
[Prate VI—Puan & Sections. |

A NEW caye was discovered on the eastern side of Gibraltar
on August 15th, 1902. It is situated a short distance south of
the eastern end of the tunnel which pierces the Rock, from the
Dockyard on the western side to ‘ Monkey’s Quarry’ on the
eastern. Blasting and quarrying operations are being carried on
in the quarry, to procure material for the new dockyard. An
explosion is said to have blown in the face of the limestone-cliff,
and a small hole was discovered; when this was entered, it was
found that it led into a cave of considerable dimensions. I have
not been able to determine whether the hole was made in the
‘massif, or whether the explosion merely blew away the rubble and
breccia that forms the talus of the cliff, thereby uncovering an old
entrance. Further quarrying operations have so enlarged the opening
that none of the original cliff-face remains very near it. Iam told
by Mr. A. K. Peaty, Assistant Civil Engineer, that he saw the
opening two hours after it had been made, and that, in his opinion,
the hole had been pierced through the massif, and was not a re-
opening of the old entrance. In any case, it must have been very
near an old entrance, as a glance at Pl. VI, fig. 1 shows that
the stalagmite-floor slopes up to within a few feet of the present
opening, and the sides of the cave, so far as they can be seen through
the accumulation of fallen rock, clearly indicate that an old entrance
was very close at hand. Moreover, this stalagmitic floor does not
rest upon the solid rock, but upon a mass of breccia of unknown
thickness; and it seems probable that, if this were removed, the
original floor of the cave would be found at a much lower level.

It' may be desirable to describe, first of all, the situation of the
cave and its general features, and then to point out some of the
interesting problems which it presents.

Fig. 1 (p. 31) shows that the cliff comes down at this place to a
platform formed by the quarrying away of the talus, 64 feet above
sea-level. The cliff consists of massive limestone, in which no
bedding can be detected. There is a small fault to the south of the
entrance to the cave, and this probably forms one side of the cave
itself. The talus consists of coarse rubble, resting upon similar
material of more ancient date which is now consolidated into a
breccia. This platform was covered, before the quarrying began, to
a large extent with roughly-stratified fine and coarse rubble, similar
to that which still remains iv situ immediately south of the tunnel.

The present entrance to the cave is 24 feet above the platform,
and 88 feet above sea-level. On entering the cave, a fine view is

Vol. 60. | NEW CAVE AT GIBRALTAR. 3k

obtained of the ‘ main hall,’ and of the stalactites and stalagmites
with which it is decorated. Some of these are of considerable size,
and measure from 3 to 5 feet in circumference, 3 feet from the ground.
The hall has a width of 45 feet, and an estimated height of 70
at its greatest. It will be at once observed that the tloor slopes
westward at a considerable angle, about 20°. This slope, as will
be seen in Pl. VI, fig. 1, continues for a distance of about 140 feet
to a point 19 feet above sea-level. The floor is very smooth with
stalagmite, and some of the fallen stalactites are firmly recemented
to it. The southern side of the main hall is for some distance
striated, as if from the action of blown sand.

Fig. 1.—Section at Monkey’s Quarry, Gibraltar.

. W.
— | ak =.
Ud ees a :
Massif ;
| \ ; x
Lary ery ee
— i 2
uae Floor sae ;
ees eens BP > ea
S EORS: pire Ree ae Sa ee Br =
: : ca
' , a {ais -
2 Rete he
+ Jy! =p.
*y ee
i ies
!

Sea-Level¥_

At this point (1 in the section, Pl. VI, fig. 1), the lower gallery
begins. This runs almost horizontally for a distance of 180 feet,
turning to the south-west at 120 feet; then there is a sharp dip
downward, and the passage becomes so narrow that it is impossible
to proceed very far. Fig. 1 in Pl. VI shows that, as a matter of fact,
the end of the horizontal part of the gallery is a few inches higher
than the entrance, and that there is a slight rise about halfway
along, but this is probably due to the unequal filling-up of the
floor, and also to the unequal deposit of stalagmite. The mean height
of the floor above sea-level is about 164 teet, and the lowest point
reached in the descending fissure is very little, if anything, above
the level of the sea. There is no standing water here or elsewhere
in the cave, except one or two small puddles. The sides of this
fissure are honeycombed in a very marked manner, to the height of
about 10 feet from the floor. The pittings are from 3 to 5 inches
in diameter, and about 13 inches deep. The sides and roof of the
fissure, at the point where it begins to turn down, are smooth and
waterworn, but the descending part, as far as could be seen, is not
so, except the floor, which is smooth because it is covered with
stalagmite. ‘The floor has been opened at a point marked 2 on the

32 MR. H, DYKE ACLAND ON A (Feb. 1904,

section (Pl. VI, fig. 1), to the depth of 15 feet. Below is a rough
drawing of a section of it (fig. 2).
Beneath the stalagmite-floor, which varied in thickness from a
few inches to a foot or more, was a layer of fine calcareous sand.
Then came coarser sand, and then rubble down to the depth of 11
feet. Embedded in the coarse sand and rubble were angular and
subangular boulders of limestone, some of large size. A complete
change then took place, and there came a bed of hard calcareous
grit, the coarse grains of sand, small pebbles, fragments of shells,
and small stalactites being cemented together by some material
closely resembling stalagmite. This bed was several inches thick

Fig. 2.—Section of the floor in the eave at Monkey's Quarry,

¥°S 5
Gibraltar. e

Se ae ES
Sates. (as | aa > een ote

' SACHETS Ors F r CS ee EPG Sere Sea
mars AVes eee erie ih es (POTS ee ans : ree
See te ON A 8 Teg We See eae , Fine Calcareous Sand

~ * eT ee ele at ate Pi ’ 5

u t> 5 . ‘ as 1 4
= ‘ . M ee egy sian! ‘ “ z
‘ 5 Bact 4 SOR on§
- oe he PRR ica SU eae

iat . 5 4 =—
EL OE a RL LAPIS boas Oe osc

or, 7 4

aN Ion Scan, Beat eae Xoo, o opm oe POF Qg cB ry

tb te heya i R ‘ee are #e\l9 Mg re :

oe ar 92S EN 02° <2 Coarse Calcareous Sand
ao has

Rubble

Cc
iw “757 we AG .
12 weti= 2, Calcareous Grit
ARE ks
. “<-~ 7 Stones bored by Pholades,
Oe ‘Echinids & barnacles.

es a =

Se ee

pees) SRock Floor. 5 a
Win thane I) |

where it lay between the boulders. In it and below it were numerous
well-rounded stones, some of them pierced by Pholas. There
were also a few scattered chips of angular limestone. At 13 feet
J found echinids and barnacles.

The shaft was sunk down the side of the cave, which was
smooth and waterworn, and in places there were holes apparently
bored by Pholas. At 15 feet the side sloped inward rapidly
towards the centre of the gallery, and the bottom of the shaft was
solid rock. JI have no doubt that this is the original floor of the
cave. At this point, therefore, it is about 2 feet above sea-level.
There were a few inches of fresh water at the bottom, and although

Vol. 60. ] NEW CAVE AT GIBRALTAR. 33

the rise and fall of the tide is 3 feet, the level of the water did
not seem to be affected by it.

At point 1, a small vertical cliff, some 30 feet high, is seen.
This is the termination of the floor of the upper gallery. It is much
undercut on its southern face, which forms the side of the lower
gallery, and is evidently the massif of the Rock. This cliff has
to be ascended by a ladder. The gallery has some fine stalagmites
and stalactites in it, and is 127 feet long, 20 to 25 feet wide, and
30 to 35 feet high. There is a narrow and irregular opening, about
55 feet long, from this upper gallery to the lower, on the south side
of the former. The western end is waterworn, and has no fissure
visible; it is now quite dry, there being no drip from the roof. I
opened the floor in the bay at the side, and in the centre. I found
a thin coating of stalagmite, and at the side some red soil 2 or
3 inches deep, and then reached the solid rock. In the centre,
below about 6 inches of moist and clayey earth, probably derived
from the decomposition of the limestone, there was a layer of
coarse and fine calcareous sand and pebbles, 3 to 4 inches deep
over the solid rock. ‘There was very little residuum from the sand
when I dissolved some of it in hydrochloric acid. The sides of this
gallery are not honeycombed in the same way as those of the
lower gallery are. The pittings are not so numerous, and have no
regularity.

From point 1, another gallery (if it can be so called) extends
eastward. At first the roof is a thin sheet of stalagmite, which
gradually curves over, so that in time the entrance would be com-
pletely hidden. A few feet inside the entrance the roof is seen to
be composed of breccia, the fragments being very firmly cemented
together. Some of these fragments are of large size, measuring
6 feet by 4 by 2. The floor is of the same formation, and in
places the breccia is being covered with stalagmite. It is a rough
scramble to get up the slope. Some 90 feet from the entrance
the breccia ceases to be visible, and its place is taken by rubble,
large and small. This I attribute to constant falls from the
roof, which have perhaps been assisted by the blasting operations
outside. It was not possible during my several visits to get more
than about 135 feet to the eastward. ‘This is, however, manifestly
beyond the present eastern face of the Rock, and therefore outside
what must have been at one time the main entrance to the cave,
which is now blocked by a large accumulation of breccia and rubble.
By scrambling down a steep slope to the north, at a point some
30 feet from the entrance of this gallery, the original side of the
cave can be reached, and on it honeycombing is visible for a distance
of 30 feet or so, and is then again buried under the breccia. The
highest point of the pitting is about 28 feet above sea-level. This
corresponds with the honeycombing that is visible in the lower
gallery, and is to be attributed to the same cause. At no place
could I find any evidence of the position of the solid rock in the

Q. J.G.8. No, 237. D

34 MR. H. DYKE ACLAND ON A [Feb. 1904,

floor, and it would evidently require the removal of a large amount
of rubble and breccia to reach it.

Such is a brief description of the general character of the cave.
It remains to point out one or two of its more interesting features
from a geological point of view.

Gibraltar, as is well known, has many examples of both fissure
and marine caves at very various heights above sea-level, St. Michael’s
Cave on the western side being perhaps the most famous of the first
kind, and the caves on the eastern coast-line of the second. There
can be no doubt that the upper gallery in the cave just deseribed
is wholly or partly of marine origin, from the character of the
concave and unfissured end, the sand and pebbles formed beneath
the stalagmite-floor, and the fact that the floor is horizontal. It is
equally evident that the main hall and lower gallery originated
in a fissure, and were subsequently exposed to the action of the sea.
The presence of echinids of the same species as those which still
exist in the Mediterranean makes it probable that the upper
gallery is the older, and that the Rock has been elevated since the
upper gallery received in a great measure its present form.

The band of honeycombing is evidence that the water must have
remained at the same level in the cave for some considerable time.
The edges of the pittings are so sharp that they cannot have been
exposed to the action of moving water for any lengthy period. They
are not seen in the shaft in the lower gallery below the level of
the present floor, and the side of the cave at that point has the
appearance of having been planed down by the sea. It is not likely
to have been fresh water, as it is difficult to see whence any con-
siderable stream of the latter could have come, or whither it could
have gone.

The striations on the south side of the main hall may be due to
the action of blown sand. Very similar markings of recent origin
are to be now seen on the sides of the entrance to the well-known
Monkey’s Cave, which lies a short distance to the south, and there
a heap of sand lies in the cave. If the striations in the main hall
are due to this cause, it shows that there must have been a large
opening to the cave on a much lower level than the present one.

By the kindness of Dr. A. Smith Woodward, F.R.S., and Dr. F.
A. Bather, M.A., the echinids have been identified. ‘They are Stron-
gylocentrotus lividus, a species still common in the Mediterranean.
The cave must therefore have been open to the sea at a com-
paratively-recent geological period. The bed of sand and Pholas-
bored stones in which they were found was about 4 feet thick, above
which are 11 feet of rubble, sand, and stalagmite. The rubble may
be attributed to falls from the roof.

The breccia brings us to the last page in the history of the cave
until its recent discovery. I believe its origin to be twofold. It
will be observed that the floor of the main hall slopes considerably

Vol. 60. | NEW CAVE AT GIBRALTAR. 35

inward from the entrance. The middle gallery enables us to see
that the old entrance is blocked up by breccia. That its position is
not due to the force of the waves is evident from its being breccia,
and not conglomerate. Sir Andrew Ramsay & Prof. James Geikie
in their paper’ discuss at considerable length the origin of the
breccias of Gibraltar, and they consider that ‘they belong to two
distinct stages,’ although in the map which accompanies their paper
the same sign is used for both. The discovery of the echinids in the
lower gallery tends to disprove that the later breccias, at any rate,
owe their origin to ‘cold climatic conditions.” When the tunnel was
made through the Rock, from the west near the Moorish castle, to the
catchment-area above Catalan Bay, a narrow fissure was discovered
that extended vertically from the outer air to an unknown depth.
If this went so far down as to reach the sea-level and was then
undermined, it would cause an enormous fall of rock, and if that
happened at the mouth of a cave, no doubt some of it would fail
inside and form a sloping floor such as there is in this cave. In
course of time the rubble would be consolidated into breccia.

The conclusions, therefore, that may be arrived at from the
evidence furnished by this cave are :—

1. That it existed as a fissure-cave before it was subjected to the
action of the sea.

2. That it had a large entrance open to the sea for a Jong period.

3. That during that time the Rock was elevated some 42 feet.

4. That it was closed to the sea at a recent geological period.

5. That the breccia and sand-slopes at this point on the eastern
side of the Rock, which are 150 feet wide and reach to a height of
200 or 500 feet above sea-level, date from a still more recent epoch.

In conclusion, I wish to express my obligations to the Admiral
Superintendent for allowing me the opportunity of examining the
cave; to Mr. A. Scott, Chief Civil Engineer, Messrs. L. T. Stoddard
& A. K. Peaty, Assistant Civil Engineers, and Mr. R. Taylor,
contractor’s agent; to Mr. R. I. Ingles, one of his superintendents ;
and to the Hon. F. W. D. Smith, M.P., for much courtesy and
assistance in the way of plans, photographs, ete.

EXPLANATION OF PLATE Vi.

Fig. 1. Longitudinal section of the cave at Monkey's Quarry, Gibraltar, on
the scale of 40 feet to the inch.
2. Plan of the cave at Monkey's Quarry, Gibraltar, on the scale of 40 feet
to the inch.
3. Transverse section of the same at XY.

Discusston.
Dr. A. Smirx Woopwarp expressed satisfaction that renewed
' Quart. Journ. Geol. Soe. vol. xxxiv (1878) p. 515.

2 Ibid. p. 530.
d2

36 A-NEW CAVE AT GIBRALTAR. [Feb. 1904,

attention was being paid to the caverns of Gibraltar; and con-
gratulated the Author on his work. Although the result was
different from what might have been anticipated, he hoped that the
Author.would continue his search for ossiferous deposits in that
cave. Many interesting species of mammals had been obtained
by Brome, Busk, and Falconer, but the known. remains were so
fragmentary that more satisfactory specimens were much needed.

Dr. Henry Woopwarp said that great interest attached to the
exploration of the caves of Gibraltar, as in the earlier ones ex-
plored by Brome, Busk, and Falconer some very interesting deposits
of bone-breccia had been met with. At the time when Busk ex-
amined them but little interest was felt in the small rodentia, as
they were believed only to be common well-known forms; but
Dr. Forsyth Major, who had lately examined some specimens, had
detected Layomys and other interesting remains, and earnestly
desired to obtain more material for study, to which the Author’s
communication promised possibly to lead up.

The AvrHor replied that the bone-breccia on the western side
of the Rock was probably of a different date from the breccia on
the eastern side.

Geol. Soc. Vol. LX, Pl. VI.

= .

2 | +e a ;

aa"

“Mass i§

Floor o

Brecc

if

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

Fig. 1. LONGITUDINAL SECTION OF CAVE AT MONKEY’S QUARRY, GIBRALTAR.
——— Section on line A. B. C. D. E. F. [lower gallery] Fig.2.

Scale:- 40 feet =1 inch
105 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200
EP Ls TES -

Reference to Numbers.
Point where the Lower Gallery begins.
2 Place where the floor was opened.
Massif 3-4 29 ft. Honeycombing 28 to 26 fs. above sea-level.

5 Lowest point explored in the Middle Gallery 16 ft above sea-level.

be

ia

St
-
1
-4
=X
‘
—4
t
—~
-——
=,
.
— 4
aaa!
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7
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ime -—,
r —
1
o —4

Rubble

Opmer Gallery

Section on line G. H.——

Massif

Breccia

Honeycombed
°5

Fig.2,. PLAN OF CAVE AT MONKEY’S QUARRY, GIBRALTAR.

Scale:- 40 feet=1 inch

I0s5 0 10 20 30 40 50 60 70 80 9g0 100 10 120 130 140 150 160 170

180 I90 200 feet

3
2
5
eA
3
ES
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4
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ta A - a
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——

Gah = ————

Section X. Y. caer

od

i meal hea he Zs

+

Vol. 60. | THE GLACIAL GEOLOGY OF TASMANIA. 37

4, A Conrrisution to the Gractat Gerotoey of Tasmania. By
J. Watter Grecory, D.Sc., F.R.S., F.G.8., Professor of
Geology in Melbourne University, Victoria. (Read December
2nd, 1903.)

|Puates VII & VIII.]

ConTENTs.
Page
SP RUPE HAIN Sy, y cass cies otiee heed nde strug toate nd o0a esas ote aeiics 37
II. The Geology and Topography of the Area ............... 37
Ee COW AOMS PUCOORUS in Poa cue cps cys coes adnad coe kaise Soe vwaiedesoenon 38
IV. The Glacial Deposits of the King and Linda Valleys ... 48
V. The Origin of the Kihg-River Glacier ............000...... 48
VI. The Range of the Pleistocene Glaciation .................. 49
Rae The Age of the Glaciation «..siivedcas dis dee cds cose ceatecen sae 02

I. Inrropucrion.

THe existence of Pleistocene glaciation in Southern Australia has
been so often affirmed on unsatisfactory evidence, that the assertion
of a recent glaciation in ‘Tasmania has been received with doubt.
Two years ago I read through the literature on the glaciation of
Tasmania, and came to the conclusion that, except for such traces
of high-level glacial action as those at Mount Sedgwick, recorded
by E. J. Dunn and 'T. B, Moore, and those near the summit of
Mount Ida, recorded by Officer, Balfour, and Hogg, the evidence
consisted of material that was either not of glacial origin, or was
due to glacial action at some Upper Paleozoic date. The advocates
of a low-level, recent glaciation in Tasmania were men who had
apparently received no special geological training, and who had
not written other papers by which the value of their geological
observations could be tested. ‘The professional and the trained
geologists were almost unanimous in denying the existence of signs
of recent ice-action in the lower valleys of Tasmania.

Il. Tae Greotocy anp ToroGRAPHY OF THE ARBFA.

It may be advisable here to introduce a short statement of the
geological structure and physical geography of that part of Tasmania
in which the deposits described as glacial occur. Most of them
have been recorded from the country beside the West-Coast Range,
and the western part of the Central Plateau of Tasmania. The
West-Coast Range runs north and south, at a distance of 20 to
25 miles from the western coast of Northern Tasmania. It consists
of a series of isolated masses of coarse conglomerates and quartzites,
of Devonian age. These masses are parts of a formerly-continuous
sheet, which has now been reduced to a series of disconnected

38 PROF. J. W. GREGORY ON THE [ Feb. 1904,

outhers, resting upon Ordovician rocks and upon a series of schists
which are probably Archean.

The chief peaks of the West-Coast Range, taken in ore from
south to north, are Mount Sorell, Mount Darwin, Mount Jukes,
Mount Huxley, Mount Owen, Mount Lyell, Mount Sedgwick,
Mount ‘l'yndall, Mount Geikie, Mount Read, and Mount Murchison.
West of this line is a broad peneplain composed of contorted slates
and sandstones, with some limestones, of Lower Paleozoic age. The
surface slopes westward towards an old coast-line, several hundred
feet above the present sea-level. East of the West-Coast Range,
and separated from it by the valley of the King and Murchison
Rivers, is the great Central Plateau of Tasmania. This plateau is
composed, in the main, of Silurian and Carboniferous rocks, which
are covered unconformably by a broad sheet of Mesozoic diabase,
represented on Mr. R. M. Johnston’s map of the Geology of Tasmania
as forming the surface of the main part of the tableland. The
southern part of the West-Coast Range is drained by the King River
and its tributaries. This river flows past the eastern base of Mounts
Sedgwick, Lyell, and Owen, and then cuts across the Range in a
canon between Mounts Huxley and Jukes. It bends northward
and is joined by the Queen River, which drains the western slopes
of the range from Mount Sedgwick to Mount Owen. The Linda
River, also a tributary of the King, occupies a broad valley eroded
along a fault-line ; it breaks through the West-Coast Range, between
Mount Owen on the south and Mount Lyell on the north.

A high ridge capped by diabase, and known as the Eldon Range,
runs out westward from the main Central Plateau; an outlier of
this ridge forms the peak of Mount Sedgwick. Farther north
is Cradle Mountain, a bold bluff forming the north-western corner
of the Central Plateau. The streams from this mountain flow
either directly into the Pieman River, or northward, past Mounts
Romulus and Remus, into the Mackintosh River, the upper part
of the Pieman. The country around the Mackintosh is a broad
plateau, through which the rivers flow in deep and narrow gorges
of recent age. The Pieman River flows directly into the Southern
Ocean, while the King River flows into Macquarie Harbour, near
the town of Strahan.

II]. Previous Recorps.

A brief summary of previous work on this subject will, I think, be
useful, as the literature is scattered and its interpretation in Europe
may be somewhat difficult.

The first recognition of glacial action in Tasmania was apparently
in the ‘ fifties,’ by Charles Gould, formerly the Government Geologist
of ‘Tasmania. His observations were never published; but his con-
clusions were verbally handed down, and have been referred to by
Mr. R. M. Johnston,’ who, in 1888, on the strength of this evidence,

1 «The Glacier-Epoch of Australasia’ Proc. Roy. Soc. Tasm. vol. iv, 1895
(1894) p. 92.

Vol. 60. | GLACIAL GEOLOGY OF TASMANIA. 39

accepted the former occurrence of local ice-sheets in the Mackintosh
Valley.

The earliest-published suggestion of the recent glaciation of
Tasmania known to me is in a report by Mr. T. B. Moore, issued
in 1883.' In this report the author refers to a boulder-deposit on
‘Painter's Plain’ in Central Tasmania, at the junction of the
Franklin River and its tributary, the Loddon; these plains are
at the height of 1220 feet above the sea. Moore describes the
bed as an
‘accumulation composed of every variety of rock, with large boulders of green-
stone strewn over the plains. These boulders are also met with cropping out
on the tops of the surrounding quartzite-hills. It is quite possible that these
masses of greenstone, occurring as they do in solitary blocks or groups, have
been brought, in the Glacial Period, from the higher lands of Mount Lyell, or
the Eldon Range, and deposited by that agency in their present resting-place.’

Further evidence was advanced two years later in a paper by
C. P. Sprent,* who claimed a glacial origin for some erratic boulders
in the Mackintosh Valley. The Mackintosh or Upper Pieman
River flows through a gorge which is said to be 1400 feet deep, and
cut through a plateau about 2000 feet above sea-level. Sprent
crossed the Mackintosh, between its tributaries the Bingham River
and the Cradle River, which flows from Cradle Mountain; hence
his locality can be closely determined, and it is clearly in the high
plateau of North-Western Tasmania.

Sprent’s most striking evidence was the discovery in the Mackin-
tosh gorge of some granite-boulders, 5 tons in weight. The
adjacent rocks were of sandstone; he could find no granite i
situ; and thought it impossible to account for the occurrence of
these granite-masses ‘except on the glacial supposition.’ This
evidence was not convincing, for the erratics might have come
either from Upper Paleozoic glacial deposits, or even from local
granite, which might have occurred in the district. Sprent asserted
(op. crt. p. 58) that
‘traces of glacial action are common all over the West Coast in locatities close
to the high mountains ’:
he gave, however, no evidence in support cf this view, and stated
that

‘it is probable that these glaciers did not extend to the low lands.’

Mr. Johnston, in his voluminous work, ‘The Geology of Tas-
mania’ 1888 (p. 164), admitted glacial action as

‘an important agent in the denudation of the immense canons or gorges
which trend away from the elevated plateau [of North-Western Tasmania]
westward.’

But he agreed with Sprent that the glaciers were local in their

' « Bxploration.— Mr. 'T. B.Moore’s Report upon the Country between Lake
St. Clair & Macquarie Harbour’ Parl. Pap. Tasm. vol. xlv (1888) no. 56,
p. &

2 ¢Recent Explorations on the West Coast of Tasmania’ Trans. & Proc.
Roy. Geogr. Soc. Austral. Vict. Branch, vol, iii (1887) p. 58.

40 PROF. J. W. GREGORY ON THE [Feb. 1904,

range, and limited to the highlands of the Central Plateau. Johnston
considered ' Sprent’s erratics

‘as due to small glaciers in alpine situations, of which there is some evidence
in the deep sub-alpine valleys of the Western Highlands of Tasmania.’

The author was emphatic * that

‘there is no similar evidence [to that in the Nurthern Hemisphere] of a severe
Glacial Period in the Southern Hemisphere.’

He repeats that

‘in ‘Tasmania a greater elevation of the land, dating from the close of the
Paleogene Epoch, result{ed] in a limited amount of glaciation in alpine regions
only.’

Further arguments in support of the view that ‘Tasmania had
suffered no severe glaciation in Kainozoic times were advanced, in
1886, by Prot. F. W. Hutton,’ on the evidence of the distribution
of Siphonalia maxima. He maintained that

‘Tasmania has not undergone a glacial epoch since S. maxima lived on its
shores.’ *

The first conclusive evidence of Pleistocene glacial action in
Tasmania was published by Mr. E. J. Dunn in 1894.’ In this
paper he showed the occurrence of an extensive glaciation in the
country around Lake Dora, to the north-east of Mount Tyndall.
Mr. Dunn’s experience as a glacial observer left no room for doubt
as to the accuracy of his observations ; but they were confined
to the evidence of glacial action on the summit of the Western
Highlands, and gave no proof of any extension of the glacial
action to low levels. Mr. Dunn also recorded the occurrence near
Mount Read, north-west of Mount Tyndall, of some glacial deposits
belonging rather to the close of the Paleozoic or beginning of the
Mesozoic Era. Their altitude is apparently about 1100 feet above
sea-level.

A further account of the glaciation near Mount Tyndall was given
by Mr. T. B. Moore in a short, but important, contribution issued in
1894.°. He described abundant traces of glacial action around
Mount Tyndall (3875 feet) and Mount Sedgwick (4000 feet); and
stated that the rocks were glaciated to within 20 feet of the summit
of Mount Tyndall, and to near the summit of Mount Sedgwick.
The eastern slopes of those mountains he described as swept bare
by glacial action. On the north-eastern side of Mount Geikie
(3950 feet) he found a well-marked roche moutonnée, which he
named after Montgomery. He gave further information as to a
glaciated rock, found by Mr. Dunn, which he called ‘Dunn’s Boss,’

' «The Geology of Tasmania’ 1888, p. 215. 2 Op. cit. p. 296.
‘On the supposed Glacial Epoch in Australia’ Proc. Linn. Soc. N.S.W.
vol. x, 1885 (1886) pp. 334-41.
+ Op. cit. p. 337.

° ‘Glaciation of the Western Highlands Taisen: Proc. Roy. Soe. Vict.
n.s. vol. vi (L894) pp. 188-38 & pl. viii.

® «Discovery of Glaciation in the Vicinity of Mount Tyndall in Tasmania’
Proc. Roy. Soc. Tasm. vol. iv, 1893 (1894) pp. 147-49.

te

Vol. 60. | GLACIAL GEOLOGY OF TASMANIA. 41

‘after the discoverer of glacial action in Tasmania.’’ Moore also
found, on the western slope of the West-Coast Range, a series of well-
preserved moraines ; some of them lay beside the western ends of the
small lakes, which lie scattered in the valleys between the chief
peaks. Beside Basin Lake he found one which he called the Hamilton
Moraine ; another he described as occurring on the northern side
of Lake Margaret ; and a third to the north of Mount Tyndall. The
ice that formed these moraines Moore estimated as being 1000 feet
in thickness. That the deposits were post-Carboniferous in age was
proved by his discovery of boulders of Carboniferous rocks in the
moraines,

As Dunn had previously recognized recent glacial action in this
district, there seemed no reason to distrust Moore’s evidence, in so far
as it related to the summit of the higher plateau of Tasmania ; but
his arguments in favour of an extension of the former glaciers to a
lower level were less convincing. In a note, published at the same
time as his paper on Mount Tyndall, Mr. Moore reported the existence
of morainic material at low levels in the broad valley of the King,
and its tributary the Linda. He stated, for instance, that a moraine
connects the eastern flank of Mount Owen to some hills in the King
Valley, known as the Thureau Hills. These localities range from
900 feet down to only 400 feet above the level of the sea.

Mr. Moore was emphatic as to the origin of these deposits, and
he had excellent sections on which to found his opinion. For he
claimed that the material worked at the old King Lyell Mine was
glacial. He wrote

‘it will be interesting for the Linda gold-mining shareholders to know that the
deep ground hydraulically sluiced on their sections is nothing but a huge mass
of morainal matter; many of the large boulders and smaller accumulations of
stones of a soft nature are beautifully scored.’

This evidence would have appeared conclusive, had not Moore's
views been opposed by geologists whose opinion carried greater
weight. Thus Mr. A. Montgomery,’ the Government Geologist of
Tasmania, in a paper published later in the same volume, treated the
occurrence of the Carboniferous fossils of Mount Sedgwick, which
Moore regarded as ice-borne erratics, merely as proof *

‘that the sedimentary strata [the Carboniferous| there too underlie the green-
stone-capping ’

of that mountain. He objects that the fossiliferous conglomerate
was not due to the action of floating ice, but

‘that it is a moraine-drift derived from the lower beds of the Carboniferous
formation, which, farther north, near Barn Bluff and Cradle Mountain, consist
mainly of conglomerates. These would supply the stones of granite, slate,
porphyry, ete., which Mr. Moore has noticed, and also the fossils’

' Proc. Roy. Soc. Tasm. vol. iv, 1893 (1894) p. 148.

* ‘Glacial Action in Tasmania’ Proc. Roy. Soc. Tasm. vol. iv, 1895 (1894)
pp. 159-69.

3 Ibid. p. 161.

42 PROF. J. W. GREGORY ON THE | Feb. 1904,

Montgomery adduced further evidence of glacial deposits in the
same district of Tasmania, but he adopted somewhat extreme views
as to the powers of ice. He remarked that *

‘the great lakes on the Central Plateau are almost prima-facie evidence of
glaciation,’

and attributed to ice-erosion the formation of the deep river-gorges
in the north-western plateau of Tasmania. He argued that
‘if we allow that the deep valleys at the head of the Pieman Were once occupied

by glaciers, we must admit that the ice came down to within 500 or 600 feet of
the present sea-level.’ *

Further, he remarked that the lower limit was possibly at places
which are now 500 or 600 feet above sea-level, and he considered
that the country then stood at a lower level than at the present time.
Finally, he quotes Johnston’s view

‘that there is no evidence of glacial action in the lower lying lands, and regards
the glaciers as having been of sinall extent. While inclined to believe that the
ice-covering has been more extensive than he is disposed to allow, in the main

I agree with his view, and do not think that the whole country could have been
ice-bound.’ ®

While Montgomery disputed part of Moore’s interpretation of the
deposits on Mount Sedgwick, Messrs. Graham Officer, L. Balfour,
and EK. G. Hogg denied the glacial origin of his low-level deposits
in the Linda Valley. They themselves reported the evidence of a
boulder-clay, with scratched boulders, only 1 mile from Strahan on
Macquarie Harbour.’ They described this deposit as very hard, and as
possessing that peculiar pinkish-purple colour characteristic of some
of the ancient glacial beds of Victoria. They apparently regarded
these low-level glacial deposits near Strahan as of the same age as
those of Bacchus Marsh. They carefully examined the moraines
described by Moore in the Linda and King Valleys, and disputed
their glacial origin. They described the moraine at Gormanston,
in the Linda Valley, regarding which Moore gave most details, as

‘a great accumulation of angular débris which has gravitated from the adjoining
heights. We are inclined to think that much of the morainal matter referred
to by Mr. Moore is simply this gravitated débris.’ (Loc, cit.)

They regarded it rather as a talus-heap than a glacial deposit. The
moraines reported at a still lower level in the King Valley they
also doubted, and they suggested that the greenstone-boulders found
there might have been derived from local dykes. They supported
their explanation by the remark

‘we may add that other evidence of glaciation in the form of roches mou-
tonnées and ground-moraines seemed to be quite absent.’ °

Proc. Roy. Soc. Tasm. vol. iv, 1893 (1894) p. 165.

Ibid. p. 164. ° Ibid. pp. 168-69.

‘ Geological Notes on the Country between Strahan & Lake St. Clair (Tas-
ania)’ Proc. Roy. Soe. Vict. n. s. vol. vii, 1894 (1895) pp. 123-24.

Ibid, p. 125,

we Ww =

=

m

an

Vol. 60. | GLACIAL GEOLOGY OF TASMANIA. 45

The authors of this paper were well acquainted with the Paleozoic
glacial deposits of Victoria, so that their opinions naturally carried
much weight ; and they were soon supported by Mr. Rk. M. Johnston,
in his paper on *‘ The Glacier-Epoch of Australasia.’ ’ He wrote that

‘the absence in lower levels of any evidence of ice-action confirms my opinion
as to the absence of intense glacial action during our Glacial and Pluvial
Kpocks.’

He accepted glacial deposits ‘on the 2182-to-2400 ft. Plateau
between Mount Sedgwick and Mount Tyndall; but he suggested
that even some of these bigh-level glacial beds may be of Upper
Paleozoic age. He said’:

The occurrence of what appears to be the older conglomerates, so closely
associated with newer drifts . . . . suggests doubt as to whether some of the
moraine-stuff, found on the flanks of [the] western mountains, upon whose

crests this older conglomerate rests, may not be confounded at times with the
true noraine-stuff of the more recent glacier-epoch.’

Further proof of the existence of the Upper Paleozoic glacial
beds in ‘Tasmania has been recently advanced by Mr. A. E. Kitson.’
He has described their occurrence at Wynyard, in a section which
is important, because it demonstrates that these deposits underlie
Middle Coal-Measures.

The previously-cited literature proves the occurrence in North-
Western Tasmania

(1) of Carboniferous glacial beds ;

(2) of high-level, recent glacial deposits— proved by Messrs. E.J. Dunn, T. B.
Moore, Graham Officer, ete. ; further deposits probably of glacial
origin but of doubtful age, have been remarked by Sprent, ete. ;

aud (3) its general conclusion—denied, however, by Mr. Moore, and to some
extent by Mr. Montgomery—is, that the recent glaciation was con-
fined to high levels.

LV. Tar GractAt Deposits or ton Kine anp Linpa VALLEYs.

Despite, therefore, the clearness cf Moore’s description, the
literature on the glacial geology of Tasmania led me, in 1900, to
accept Johnston’s conclusion that the last Tasmanian glaciation was
limited to high levels, and that the reported low-level
glacial deposits were either Upper Paleozoic in .age,
or not glacial.

In the railway-journey across North-Western Tasmania, from
Emu Bay to Macquarie Harbour, I saw two conglomerates, which
struck me as resembling glacial deposits ; but I had no opportunity
of examining them, and, as the train climbed slowly up to Queens-
town, I saw many coarse gravels containing quartz-boulders, so

' Proc. Roy. Soc. Tas. vol. iv, 1893 (1894) p. 126. 2 Tbid. p. 99.
* *On the Occurrence of Glacial Beds at Wynyard, near Table Cape (‘Tas-
mania)’ Proce. Roy. Soc. Vict. n. s. vol. xv (1902) pp. 28-39.

‘SOUOUL JO a7vVaq
[YUL JO 9K

‘IUIDLOTT UOJsUNULOH 94) ULOLf sapjpnog paywwnjbh p—T “sly

Vol. 60. | THE GLACIAL GEOLOGY OF TASMANIA. 45

large that I could understand their being regarded as of glacial
origin. Absorbed in the interesting problems of the Mount-Lyell
mining-field, I had dismissed glacial questions from my mind,
especially as I found only talus-boulders at the old mine-workings,
where Moore had described a moraine. I was therefore led to
accept the view of Officer, Balfour, and Hogg, that Moore had mis-
taken coarse talus for glacial deposits. I was according surprised,
when haying occasion to cross the hill on which Gormanston is
situated, to find on its western face some beds of tough, fine, well-
bedded glacial clays, with ice-scratched boulders. Above this
deposit were beds of typical boulder-clay. One of the boulders in
the bedded clay was a foot long, and was standing on its edge; it
had compressed the layers below it, and had evidently fallen through
water from floating ice ; near it were a few scratched stones. The
boulder-clays, moreover, were clearly of recent origin, and formed
later than the excavation of the Linda Valley; they occurred as a
bank projecting from the southern side of the valley, and nearly
damming it across, like a delta. A short examination showed that
Moore was right in his view that the town of Gormanston
stands on a glacial moraine of recent geological age.

This moraine occurs now in a fan-shaped hill, a mile long by
half a mile wide; it rests against the southern bank of the Linda
Valley at the Gormanston Gap. The top of the moraine is. in
places, fairly level, and at the height of 320 feet above the Linda
Creek. For it has been planed down by the southern tributaries of
the Linda, which flows round its northern edge. The moraine
must once have extended right across the valley to the southern
foot of the ridge of Mount Lyell, where patches of it still occur.
But the moraine has been cut through by the Linda. Excellent
sections of the glacial beds are exposed in the banks of the creeks
which run from the Gormanston Gap to the Linda township, and
along the eastern side of the deposit; and also in the railway-
cuttings of the North Mount-Lyell Railway, on the northern face of
the moraine. The moraine is composed mainly of typical boulder-
clays. The bedded clays are best exposed on the western side of
the deposit, as if they had accumulated in a glacier-lake that
occupied the upper part of the Linda Valley, above the moraine-
dam.

The bulk of the moraine is formed of unstratified clay, crowded
with boulders and pebbles. The majority of the included frag-
ments are quartzites, derived from the conglomerates that form the
summits of Mount Lyell and Mount Owen. These hard materials
frequently retain their original form, but some of them show signs
of facetting, suggesting ice-action. Some of the boulders are rocks
not found in the immediate neighbourhood. ‘There are coarse blocks
of hard blue stone, exactly similar to the Mesozoic diabase which caps
the central plateau of Tasmania, and forms the crests of the Eldon
Range and the peak of Mount Sedgwick. There are also boulders
of quartzite and sandstones, probably derived from the Silurian
rocks to the east of the King River, and some blocks of hard slate

46 PROF. J. W. GREGORY ON THE [Feb. 1904,

which I found exquisitely glaciated. In the railway-cutting by Gor-
manston Station is an erratic of fossiliferous limestone, measuring
43 feet in length by 33 in width and 23 in height; it is scratched
all over, and partly polished.

The Linda moraine rises to the height of about 1200 feet above
the sea, and on the floor by the Linda Valley, near the slaughter-
yards, it is at the level of only 900 feet. A bore of the King Lyell
Mine is said to have pierced the same deposits to a depth of
280 feet, and would thus show that they occur at an altitude of not
more than 700 feet above sea-level.

That the moraine formerly extended right across the Linda
Valley is shown by the occurrence of a strip of glacial deposits on
the northern bank of that valley, immediately above the river.
But the northern side of the valley is so steep, and the Linda is
there so near to the southern foot of Mount Lyell, that but little of
the glacial deposits remain im situ. There can, however, be no
doubt that the moraine once formed a dam across the Linda Valley
from north to south, that it was cut through by the Linda River,
and that its summit has been planed down to the level of the
Gormanston Gap.

East of the moraine the floor of the Linda Valley is a level,
alluvial plain, in places half a mile wide; the glacial deposits
ean be found rising from the alluvium, on both sides, until, a little
over a mile to the east of the moraine, the valley narrows, owing
to the projection of the steep north-eastern spur of Mount Owen.
Patches of the glacial deposits can be found at intervals along the
edge of the alluvial flats on the southern side of the river. More
of the material occurs on the northern side of the valley, which is
rough and densely timbered; a railway-line for mining purposes
has recently been made round the eastern end of Mount Lyell, from
the Linda township to the valley between Mount Lyell and Mount
Sedgwick. ‘This railway crosses the eastern spur of Mount Lyell
at the height of about 1500 feet. The glacial deposits are exposed
at intervals in the railway-cutting, and they are especially well
developed in the King Valley, and along the northern foot of Mount
Lyell, at the eastern end of the Sedgwick Valley.

The North Lyell Railway shows a good section of the glacial
deposits, in the bluff above the junction of the King River and the
Linda. The railway-line has cut through an enormous boulder of
black, fossiliferous, Carboniferous Limestone. The two ends of the
boulder are exposed on the banks on each side of the line, and it
must have been at least 16 feet long.

The King River flows through a broad valley, and its floor is an
alluvial, forest-covered plain, over a mile in width. The eastern
end of Mount Lyell overhangs the valley. Mount Lyell itself is a
long east-and-west ridge, which separates the Linda Valley from a
much larger and broader valley to the north, between it and Mount
Sedgwick. The railway-cutting round the eastern end of Mount

Vol. 60. | GLACIAL GEOLOGY OF TASMANIA. 47

- Lyell exhibits unstratified boulder-clays, with many of the white
quartzite-pebbles and boulders from the conglomerates of the West-
Uoast Range; but the clays also contain a larger number of the
diabase-boulders than occur in the Linda Valley, as well as some
sedimentary rocks, which I did not find 7m situ on the eastern side
of the King River. Following the King River to the south, glacial
deposits can be traced for miles down the valley. [ll-health pre-
vented me from examining these deposits, except from the railway-
train; but their features are so distinct, that I have no doubt that
Moore was correct in his statement that the Thureau Hills are joined
to Mount Owen by a moraine (see p. 41), The glacial deposits in
this part of the King Valley descend to the level of less than 800 feet
above the sea.

The glacial evidence, at high levels, is in places remarkably
distinct. Mount Sedgwick consists of a peak of diabase, resting on
a ridge of the West-Coast Range conglomerates. This ridge runs
east-and-west. Well-marked roches moutonnées occur at
many points over the ridge near the highest peak, and the diabase
is glaciated in broad surfaces close to the summit. ‘The lakes to
the north, in the valley between Mount Sedgwick and Mount Tyndall,
are bordered by small, but well-preserved moraines: one of them
lies round the western side of Lake Margaret. These occurrences,
however, are of less interest, as they are at a higher level than that
at which the existence of glacial action in Tasmania has been called
in dispute.

With such abundant glacial evidence in the valleys, glacial
contours might be expected upon the hills; but this part of
Tasmania has a rainfall of over 100 inches in the year. The rain-
fall at Lake Margaret, according to Mr. Huntly Clarke, the Engineer
of Supplies to the Mount-Lyell Mine, exceeds 140 inches a year,
Accordingly, rock-weathering takes place at a very rapid rate,
while the sheltered slopes of the hills are covered with dense forest.
I had, however, been impressed with the strikingly-glaciated aspect
of the northern face of Mount Owen, before I had seen the definite
moraine-deposits of the Linda Valley. The northern face is smooth
and rounded, and it has been swept bare of all drift-deposits.
Hence, though I had not time to search this face for glacial strie,
I think that it may be fairly assumed that the northern face of
Mount Owen was ice-worn to the height of about 1900 feet. In
the King Valley, close by the confluence of the King and the Linda,
there is a hillock of conglomerate, the shape of which has been
rounded by the passage of ice across it. The ends of the con-
glomerate-spurs immediately south of the Linda township also owe
their rounded surface to glacial erosion; and a still better case of
glacial contours is shown by the eastern end of the spur, south of
the road from Linda to the Lyell Blocks Mine.

Moreover, looking down on the ridge of schists that separates the
Linda Valley from the Queen Valley, I noted that it appears to have
been glaciated. The schists weather so rapidly that no glaciated or

48 PROF. J. W. GREGORY ON THE [ Feb. 1904,

striated surfaces remain; but the aspect of the ridge, from the
crags of conglomerate above North Lyell, shows in places the vestiges
of glaciated contours. ‘The southern slopes of Mount Sedgwick, and
the valley between that mountain and Mount Tyndall, also exhibit
well-developed glacial contours.

V. THe Ortein oF THE Kine-River GLacter.

The origin of the glaciers and the direction of their movement is
clearly indicated by the nature of the erratic blocks. The King
Valley, east of Mounts Lyell and Owen, practically separates two
distinct types of country. On the east is a district made up of
Silurian and Carboniferous rocks and Mesozoic diabases. West
of the King River the rocks consist of some ancient schists, probably
Archean in age, some ‘ Middle Silurian’ slates, limestones, and
quartzites, and the Devonian conglomerates and sandstones of
the West-Coast Range. The only occurrence that I found of
Carboniferous rocks to the west of the King Valley is near Linda,
where there are a few narrow outcrops of black Fenestella-shales,
on the floor of the Linda Valley. This bed has been preserved
there by having been faulted down among the conglomerates. The
only near occurrence of diabase west of the King River, with which
I am acquainted, is on the summit of Mount Sedgwick. As the
glacial deposits include abundant boulders of Carboniferous Lime-
stone and shales, of sandstones (which are probably from the
Silurian rocks), and of diabase, the glaciers probably came from
the east and north-east. In that direction lies the great Central
Plateau of Tasmania, of which the Eldon Range is an outlier.

The upper portion of the King-River Valley consists of two
parts at right angles to each other. The uppermost part trends
east and west along the southern face of the Eldon Range: this
valley is continued westward by the broad valley, between Mounts
Sedgwick and Lyell,’ until it opens out onto the peneplain of North-
Western Tasmania. At the western end of the Eldon Range the
King River bends abruptly southward, while a small tributary
comes in from the north, between the end of the Eldon Range and
Mount Sedgwick.

The general evidence suggests that, during the time of this
giaciation, the Eldon Range and the Central Plateau formed the
collecting-ground of the glaciers. From this area the glaciers
flowed westward and south-westward. One glacier flowed down
the valley between Mount Tyndall and Mount Sedgwick : doubtless
it received tributary glaciers from those two peaks. <A_ well-
marked terminal moraine round the western end of Lake Margaret
marks either the farthest westerly extension of the glacier, or one
of the stages in its retreat.

1 The Upper King River probably flowed originally through the Sedgwick
Valley ; see my paper on ‘ Some Features in the Geography of North-Western
Tasmania’ Proc. Roy. Soc. Vict. n. s. vol. xvi (1903) pp. 180-81.

Vol. 60. | GLACIAL GEOLOGY OF TASMANIA, 49

A second glacier flowed along the King Valley, south of the
Eldon Range, and was continued westward along the Sedgwick
Valley to the north of Mount Lyell. It deposited a moraine,
imperfectly preserved, north of the Comstock Mine. I saw no
evidence that this glacier extended farther westward. Another
branch of the main glacier flowed southward along the present
course of the King Valley, and abutted against the eastern face of
Mount Lyell. On the melting of the glacier, the slopes of the
valley were covered with a thick deposit of boulder-clay. This
glacier continued farther southward, and deposited a terminal
moraine between the eastern base of Mount Owen and the Thureau
Hills. “A lobe from the glacier flowed westward up the valley of
the Linda—a valley due to fault-action. The ice of this lobe flowed
over the schist-ridge that separates the Linda and Queen Valleys.
It wore the conglomerate-spurs from this ridge near the Linda
township into roches moutonnées, and deposited some boulder-
clay with diabase-boulders at Queenstown, where some of the material
is still preserved opposite the Mount-Lyell Company’s pumping-
station (altitude 464 feet). During the retreat of this Linda-
Valley glacier, a glacial lake formed between the glaciers and the
Mount-Lyell ridge ; the drainage from this lake escaped southward
into the valley of Conglomerate Creek, cutting the Gormanston Gap
(altitude 1356 feet). One important stage in the retreat of this
glacier is marked by the deposition of the great Gormanston
Moraine.

VI. Tue RanGE oF THE PLEISTOCENE GLACIATION.

The extent of the Pleistocene glaciation is shown on the
accompanying sketch-map (fig. 2, p. 50). The localities marked by
asterisks are those where glacial deposits, which I regard as Pleis-
tocene, have been recorded. ‘The small letters (c) indicate localities
of glacial deposition probably dating from the Carboniferous. The
correlation of the deposits to the north and west of Mount Lyell
rests, in part, on the lithological nature of the deposits, and partly
on other indications of ice-action in their localities.

During a first visit to Tasmania I had been struck by the
morainic aspect of some beds near Farrell, on the Emu-Bay and
Zeehan Railway. The locality is about 60 miles from Burnie, at an
altitude of 1300 feet. For an opportunity of examining these beds
I am indebted to Mr. J. Stirling, the manager of the railway, who
kindly stopped the train for this purpose. The evidence available
clearly shows that the beds are of glacial origin. They include some
gigantic erratics of conglomerate: one measures 25 by 18 by 12 feet,
and numerous smaller erratics occur beside it. They are not frag-
ments, left in situ by the denudation of a band of the West-Coast
conglomerates, for they rest on a bed of clay. Mr. Stirling tells me
that, during the construction of the railway, a hole was dug into
this clay, at a culvert a few hundred yards south of the biggest

O.3.G:8) No. 237. E

Fig. 2.—Sketch-map of North-Western Tasmania, wlustrating the range
of the Pleistocene glaciation.

Carboniferous glacial beds have been recorded by Dunn,
Kitson, Officer, and Gregory. Definite proof of the age of
the strata by association with fossiliferous Carboniferous
beds is available only at Table Cape.

able Cap e
CKitxon
Vynyard

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Vol. 60. | THE GLACIAL GEOLOGY OF TASMANIA. 51

- erratic; and although the hole was 20 feet deep, it did not reach

the bottom of the clay.

Associated with the conglomerate-boulders are others of various
igneous rocks, belonging to the series of felsites. I pulled three
small boulders out of the clay exposed on the cutting for a culvert,
close to the biggest erratic ; two of the three boulders had glacial
scratches. The glacial clay was soft, though tough; it had the
lithological characters of a recent, and not of a Carboniferous glacial
deposit. Moreover, the northern face of Mount Black (altitude
about 3500 feet), the nearest conspicuous mountain, appears con-
spicuously moutonnée, affording further proof of recent glacial
action in this part of Tasmania.

Mr. Stirling kindly invited me to ride on the locomotive from
Farrell to Zeehan, and thus I had a better view of the cuttings
than I could have got from the rarlway-carriage. I was thus able
to notice that the glacial deposits occurred at intervals along the
line from Farrell to near Zeehan. As the train sometimes went
slowly up the steep grades, I had a fair view of the sections
exposed. The sections along the ascent from the bridge over the
Pieman River, up its left bank, show a typical boulder-clay, with
boulders 2 feet or more in length, embedded in a fine clay. The
shape of the boulders suggested ice-wearing, and they rest in places
upon the worn surface of the schists. Farther along the line there
are some finely-bedded clays, covered by a layer of boulder-clay.
Between Bobadill Creek and Chasm Creek are some more bedded
clays resting upon clay and slate, and overlain by boulder-clay.
The bridge over the Pieman is 400 feet above sea-level, while the
railway-bridge over its tributary the Ring River is at a slightly
lower level; and in both cases the glacial beds occur almost at the
level of the bridges. About Rosebery, at the level of 510 feet above
the sea, there are also some good exposures of boulder-clay ; the last
of the boulder-clays, however, were left some time before reaching
Zeehan. The boulder-clays in this area seem to occur in an irregular
sheet, descending in the deepest pre-glacial valleys to but little
over 400 feet above the level of the sea.

The glacial deposits of Farrell, Rosebery, and Dundas may be
assigned to the action of a Pleistocene glacier, which flowed north-
westward from the ice-sheet of the Central Plateau. Moreover,
the erratics found by Sprent in the Mackintosh Valley, at a locality
only some 6 miles from Farrell, may be safely attributed to the
Pleistocene, and not to the Carboniferous glaciation.

The railway-line from Zeehan to Strahan, on Macquarie Harbour,
passes through a series of cuttings in coarse boulder-deposits ; they
extend along the line for 2 or 3 miles, on the northern side of
the Henty River, between Mallana and Eden. They range in
altitude from about 50 to 350 feet above sea-level.

For an opportunity of examining one of these sections I am
indebted to the courtesy of Mr. Parry, the station-master ‘at
Zeehan, who kindly stopped the train for me. A four-minutes’

E2

52 PROF. J. W. GREGORY ON THE [Feb. 1904,

examination of one section showed that the beds are true boulder-
clays: the clay is tough, hard, and fine; the boulders range up to
2 feet in longest diameter, and le at all angles in the fine clay.
The shape of the boulders is characteristic of ice-action, most of them
having one or more flattened surfaces. The boulders, however,
are so decomposed that I could not find any indubitable glacial
scratches ; and they are so soft, that I could dig into them with
the hammer. They include boulders of Devonian conglomerates
and diabase, indicating a mixture of materials. There is no out-
crop of diabase in the immediate neighbourhood.

The boulder-clay at this locality consists of a series of patches ;
remnants, no doubt, of a iormerly-extensive sheet. This fact, coupled
with the extreme decomposition of the boulders, indicates a great age
for this material. Moreover, there is no indication of recent
glacial action in this locality. Therefore, although the evidence is
inconclusive, these boulder-clays may be provisionally
correlated with the Carboniferous Series; and the
boulder-clays of the Pieman Valley give the lowest
level (400 feet above the sea) yet proved for the
Tasmanian Pleistocene glaciers. It must be remembered,
however, that there is certain evidence of a recent uplift of this
part of Tasmania to the height of several hundred feet, so that
some ot the glaciers may have actually reached sea-level.

VII. Tue Ace or rHEe GLACIATION.

The only direct evidence as to the latest date at which the glacial
deposits of North-Western Tasmania were formed is derived from
their condition of preservation. Mr. Dunn has remarked on the very
recent aspect of some of the rock-scorings, and many of the glacial
deposits are but slightly worn and weathered. The moraine in the
Linda Valley has been simply rounded off and cut through by the
Linda River ; the moraines around Lake Margaret are still in excel-
lent preservation. The deposits of the main King Valley have been
more denuded, for the river has widencd that valley and removed
much of the old morainic material, except where it is preserved on
the flanks of Mount Lyell and Mount Owen. Some of the glacial
deposits, however, are little more altered than those of the North of
England, despite the heavy rainfall by which they are attacked.
And, so far as it is safe to judge the age of glacial deposits by their
condition of preservation, they may be as recent as some of the
later moraines of the North of England.

The maximum age of the deposits is given by their strati-
graphical relations. They are not only later than the formation of
a great peneplain, which is one of the most conspicuous features
in North-Western Tasmania, but they were formed after the dissec-
tion of this peneplain had begun; for some of the glacial deposits
in the valley of the Queen River at Queenstown are but little
above the present floor of the valley.

Vol. 60. | UPPER JURASSIC AMMONITES. 61

Dimensions :—

Diameter=72 millimetres. Thiekness=0°347 of the diameter.
Height of the last whorl=0°302 of the | Width of the umbilicus=0:487 of the
diameter. diameter.

Locality and Stratigraphical Position.—The specimen
described came from the Kimeridge Clay at Chippinghurst, near
~ Chiselhampton, 64 miles south of Oxford, and is in the Buckland
Collection, in the University Museum, Oxford. The species is the
zone-fossil of the Upper Kimeridge Clay.

Affinities and Differences.—The points of difference be-
tween this specimen and d’Orbigny’s type have already been referred
to. A specimen from Hartwell,in the British Museum (Natural
History), forms a link between the two, approaching the former
in haying three simple ribs, and the latter in having whorls which
are not depressed, and only twenty-five ribs at a diameter of 69 milli-
metres. As the shell is preserved, the constrictions behind each
simple rib are well marked.

Perisphinetes bipliciformis, Nikitin * is very closely related to it,
and so is Ammonites annulosus, Quenstedt.” It may be identical
with Am. rotundus, Sow., and if it is so, that namé has the priority :
I have not adopted it because the ‘type’ of rotundus is only a worn
fragment, upon which it is quite impossible to found a species.

In conclusion I have much pleasure in expressing my thanks to
Mr. 8. 8. Buckman and Dr. Henry Woodward for suggestions ; to
Dr. A. Smith Woodward for facilities for examining specimens in
the Natural History Museum; and especially to Prof. Sollas for help
in every way.

EXPLANATION OF PLATES IX-XII.
[ All the figures are of the natural size. ]

Puats IX.
Perisphinctes plicatilis (Sow.).
Fig. 1. Side view.
2. Front view.
This is Sowerby’s ‘ type’-specimen, and is preserved in the Buckland Collection,
at the University Museum, Oxford.

Puate X.

Perisphinctes hiplex (Sow.).
Fig. 1. Side view.
2. Natural cross-section.

This is Sowerby’s ‘ type ’-specimen, and is preserved at the British Museum
(Natural History).

? «Die Jura-Ablagerungen zwischen Rybinsk, Mologa und Myschkin, an der
oes aa ” Mem. Acad. Imp. Sci. St. Petersb. ser. 7, vol. xxviii (1881) no. 5,
pl. vi, fig. 52.

2 «Die Ammoniten des schwibischen Jura’ vol. ii (1886-87) pl. Ixxxviii, fig. 22.

62 MISS MAUD HEALEY ON ©: (Feb. 1904,

Puate XI.

Perisphinctes variocostatus (Buckland).

This is Buckland’s ‘type’-specimen, and is preserved in the Buckland Collection,
at the University Museum, Oxford.

Puate XII.

Olcostephanus Pallasianus (VOrb.), var. nov.
Fig. 1. Side view.
2. Front view.
This specimen is preserved in the Buckland Collection, at the University
Museum, Oxford. It is figured as an example of the ammonite which has
so long been known as Ammonites biplex.

Discussion.

The Rev. J. F. Brake congratulated the Authoress on haying
come independently, by the study of the type-specimens, to the
same conclusions as those foreigners who had studied our Upper
Jurassic ammonites. Nikitin and Pavlow had pointed out, after
their visit to England in 1888 for the International Geological
Congress, that the shell that we had been in the habit of calling
Ammonites plicatilis was what they had understood by Am. biplex,
and that what we called Am. biplex was what they knew as
Am. Pallasianus. M. P. de Loriol also had figured the latter species
under the name of Am. biplea. ,

The speaker thought that he was in a position to show that ‘the
trouble had arisen from Sowerby himself, who, to illustrate his
description of Am. plicatilis, had figured the one specimen intended
to illustrate his description of Am. biplex: while, to illustrate his
description of Am. biplew, he had figured the two specimens intended
to illustrate his description of Am. plicatilis. This (said the
speaker) was shown not only by a comparison of details, but hy
the mere fact that Am. plicatilis was spoken of in the plural, and
as occurring abundantly and in company with Am. ewcavatus in
places where the easily-recognizable specimens figured as Am, biplex
do occur in such company; while Am. biplex was spoken of as one
specimen occurring in Drift, which could not therefore be repre-
sented by two examples, though it might well be by the figure of
Am. plicatilis, which cannot be recognized as an Upper Jurassic
fossil, but whose home might perhaps be now determined, since the
Authoress had rediscovered the specimen. The use of the term
‘biplex’ for the very distinct Upper-Kimeridge form appears to
have been introduced by Fitton, who has been followed by others
until corrected by the Russians.

A curious question arises out of the mistake thus indicated. If
an author describes under the same name one specimen in the text
and illustrates another specimen in the plates, which is the type?
In the view of the speaker, if they be of different species, the name

Quart. JourN. GEOL. Soc.,

VoL. LX, Pt. XI.

PERISPHINCTES

VARIOCOSTATUS (BUCKLAND).

NAT. SIZE.

Bemrose Ltd., Collo.

ee oe
¥ ys . sf ee \
Tes « : . poe ca

wr

Quart. JouRN. GEOL. Soc., Vor. LX, PL. XIl.

Fig. 1. NAT. SIZE.

Fia. 2. NAT. SIZE.

Bemrose Ltd., Collo.

OLCOSTEPHANUS PALLASIANUS (D’ORB).
VAR. NOV.

'f.

‘
od

—
ih ee - C1]

Vol. 60. ] UPPER JURASSIC AMMONITES. 6B

belongs to the description. On this principle British geologists
have acted; but foreigners have been led by the figures.

The reference of the type of Ammonites variocostatus to the
Ampthill Clay, which represents a Corallian horizon, seems to be
correct. It appears in fragments on that horizon at Shotover, and
a fine specimen from Osmington was exhibited by the speaker. It
is the adult form of Am. plicatilis (Sowerby’s description).

Mr. H. B. Woopwarp remarked on the importance of finding
these type-specimens and of figuring them by the aid of photography.
He observed that the complexities of modern nomenclature were a
great trouble to the student, as in some lately-published manuals
different generic (or subgeneric) names were used for the same
species. With field-experience, however, one might become
familiar with the many forms of each leading species and with
the horizons which they characterized ; and the safest plan seemed
to be to identify the fossils without naming them.

Mr. E. T. Newron thought that the Rev. J. F. Blake's expla-
nations showed the desirability of publishing good figures and
descriptions of the obscure and little-known type-specimens which
formed the subject of the Authoress’s paper. The plicatiloid
ammonites were avowedly a difficult group to deal with; and a
full knowledge of the type-specimens was a necessary foundation to
work upon.

Prof. Sortas remarked that he had listened with great pleasure
to the complimentary remarks on the work of the Authoress, and
regretted that she was not present to defend before the Society
her own position in the disputed matter of nomenclature. The
Rev. J. F. Blake’s suggestion was certainly ingenious, and required
careful examination: but, whether well-founded or not, it had
always been customary to accept the evidence of so-called ‘ type ’-
specimens as conclusive. The type in the Natural History Museum
was named and figured as ‘ biplex, that in the Oxford University
Museum was named and figured as ‘ plicatilis* ; so that, unless we
abandoned our usual methods, these must be accepted as the correct
designations of their respective forms.

Postscript To THE DIscussIon.

[I am sure that Mr. Blake will be the first to abandon his in-
genious suggestion when he has seen both of the ‘types’ in
question. No one familiar with the Corallian Beds of Dry Sandford
and Marcham can doubt which of the two came from there, and
which from the Drift. But, apart from this, it is impossible to
transpose Sowerby’s descriptions, for a careful perusal of them
shows that he does not speak of Ammonites plicatilis in the plural.
The only suggestions of plurality are found in the mention of
two localities in this sentence :—

‘A sandy stratum, containing beds of sandy limestone, at Dry Sandford and
Marcham, N.W. of Abingdon, produces this shell’ ;

64 UPPER JURASSIC AMMONITES. [ Feb. 1904,

and in a reference to ‘several other ammonites’ in the following :—

‘Several other ammonites occur in the same stratum, among them is Am. con-
cavus of tab. 105; most of them have lost the shell; the present is only a
cast of the inside....’; 1

and again in a footnote referring to the said tab. 105. Further,
in the description of Am. biplee Sowerby distinctly refers to
two figures; he does not, it is true, actually mention fig. 1, but
he describes it, and says that it came from Suffolk, adding ‘ Fig. 2
is from Barrow.’* Additional evidence can be found in the suture-
line, which 1s very complicated and very clearly shown in Am. pli-
catilis, while it is only indicated here and there in Am. beplew ;
Sowerby states that ‘the septa are acutely sinuated’ in the case of
the former, and does not mention them in the case of the latter.

I hope to deal fully with Aim. excavatus at no very distant date.
It is, however, necessary to mention it now, as its occurrence with
Am. biplev has been adduced by Mr. Blake in support of his
suggestion. In one of the quotations given above, Sowerby says
that Am. concavus of tab. 105 is found with Am. plicatilis. Un-
fortunately, tab. 105 1s described as Am. ewcavatus,’ and here it
must be allowed that Sowerby has made a slip. Still, there is no
doubt that he meant Am. excavatus, as Am. concavus is an Inferior
Oolite form, and could not therefore occur in the neighbourhood of
Dry Sandford and Marcham. Now the type of Am. excavatus came
from Shotover, and we have specimens in the University Museum,
Oxford, from the Corallian, which I have identified with it ; there
is, therefore, every probability of its occurring along with Am. pli-
catilis in the neighbourhood of Dry Sandford and Marcham. Betore
accepting its recorded occurrence with Am. biplew, I should like to
see the specimens which were found together, because I am of
opinion that Am. evcavatus is confined to the Upper Oxford Clay
and the Corallian Beds, while the true Am. biplex is a Kimeridgian
form, although several species of Perisphinctes, which are related to
it, do occur in the Corallian.

There is yet another point on which I must beg to differ from
Mr. Blake, and that is in regarding Am. variocostatus’ as the adult
form of Am. plicatilis. The ribs of the inner whorls of the former
are much coarser and less numerous than those of the latter, and
the suture-line is different. At the same time, I think it highly
probable that the ribs of the adult Am. plicatilis suffered a change
similar to that which the ribs of Am. vartocostatus undergo.—M. H.,
December 5th, 1903.)

+ «Mineral Conchology ’ vol. ii (1818) p. 149.
* Ibid. vol. ii (1821) p. 168.
% Ibid. vol. ii (1818) p. 5.

Quart. Journ. Geol. Soc. Vol. LX, Pl. VIL.

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OweEN, THE GORMANOUNT-LYELL MINE OFFICES.

Bemrose & Sons. Ltd., Printers, Derby, London and Watford.

Fic. 1.—View of Mount Owen, THE LINDA VALLEY, AND THE GORMANSTON MORAINE, FROM THE RAZORBACK.

Fig, 2.—View oF Mount OWEN, THE GORMANSTON GAP, AND THE PLANED SURFACE OF THE GORMANSTON MORAINE. FROM THE HILL BESIDE THE Mount-LyeLt Mine OFFices.

Bonrose & Sons, Ltd, Printers, D

“|

Vol. 60. ! GLACIAL GEOLOGY OF TASMANIA. a3

EXPLANATION OF PLATES VII & VIII.

Puate VII.

Sketch-map of the glaciated area around Mount Lyell, including the Gorman-
ston Moraine in the Linda Valley, on the scale of 13 miles to the inch.

Puate VIII.

Fig. 1. View of Mount Owen, the Linda Valley, and the Gormanston Moraine,
from the Razorback: showing the glaciated aspect of the lower
northern slopes of Mount Owen.

2. View of Mount Owen, the Gormanston Gap, and the planed surface of
the Gormanston Moraine, from the hill beside the Mount-Lyell Mine
Offices.

Discussion.

Dr. W. T. Branrorp called attention to the fact that the Author’s
clear account of the Pleistocene glacial evidence in the Tasmanian
lowlands was an important addition to our knowledge of the
records left by the Glacial Period in the Southern Hemisphere ;
for instance, in New Zealand, in Tierra del Fuego and the neigh-
bourhood, and on the mountains of South-Eastern Australia.
Everywhere in the Southern lands the marks of ice-action resembled
those found in the Northern Hemisphere, and appeared to be of
about the same antiquity.

Mr. C. F. Hearncore said that he had been acquainted with the
district described for more than 8 years. He quite agreed with the
Author that the previous evidence as to glaciation was unreliable:
he had studied the evidence himself, and was dissatisfied with it.
The continuous rains and the extremely-close growth of the
Tasmanian ‘ bush’ made geological work on the western coast of
that island a matter of considerable difficulty, and he congratulated
those interested in the Colony on their being now able to avail
themselves of the careful record of observations which the Author
had placed before the Society.

Mr. P. F. Kenpatt remarked that it was fortunate that these
disputed points of Tasmanian geology had been studied by one so
well able to determine their merits as the Author. The phenomena
presented one peculiar feature: they indicated glaciation by ice-
sheets, not by valley-glaciers. The boulders had been brought
from great distances across a country of low relief; nor was that

* characteristic product of glaciation, boulder-clay, wanting. Glacia-
tion extending down to a few hundred feet from sea-level, in a
latitude corresponding to that of Madrid in the Northern Hemi-
sphere, was a very remarkable occurrence. Perhaps the very high
rainfall of Tasmania had something to do with it.

o4 MISS MAUD HEALEY ON [ Feb. 1904,

oO. Notes on Upper Jurassic AMMONITES, with SPECIAL REFERENCE
to Specimens iv the University Museum, Oxrorp: No. I. By
Miss Mavp Heater. (Communicated by Prof. W. J. Sotzas,
D.Se., LL.D., F.R.S. Read November 18th, 1903.)

[Puates IX-XIT.]

In the course of rearranging the Upper Jurassic fossils in the
University Museum, Oxford, my attention has been called to the
large amount of misconception which exists with soe to Sowerby’s
species Amimonttes plicatilis and Am. biplev. The former is rightly
recognized in England as the zone-fossil of the Upper Corallian, but
Dr. J. von Siemiradzki? gives the name to a specimen from the
ornatus-zone. He meee! the following surprising remark with
reference to it :—

‘ Da Sowerby’s Originale nicht erhalten sind, bleibt uns nichts anderes ubrig,
als die nachst alteste Figur von Phillips als Typus der Art anzusehen.’

The original specimen is in the Buckland Collection in the Uni-
versity Museum, Oxford; but even if it had been lost, Sowerby’s
figure would have had a better right to be taken as the type than
that of Phillips, for it has the priority and there is no ambiguity
about it, while the history of the latter is very involved and the
original, so far as I can ascertain, is not preserved. The reference
which Dr. Siemiradzki gives for it is ‘Geology of Yorkshire’
(1829) pl. iv, fig. 29, that is, the first edition, in which the figure
in question is that of a keeled ammonite and is named Ammonites
solaris ; while the figure? which he gives as an example of Peri-
sphinctes plicatilis makes it quite clear that he is really referring to
the third edition (1874), in which fig. 29 on pl. iv is that of a
species of Perisphinctcs and is described in the explanation of the
plates “ as ‘Am. solaris (erased 1874), Am. plicatis (replacing Am.
solaris), but referred to on p. 265 as Am. plicatilis, Sow. It is
therefore most probable that ‘ plicatis’ was intended for ‘ plecatilis °
on p. 325; but, granted that this is so, it in no way affects the
validity of Sowerby’s ‘type.’ The second edition (1835) of the
‘Geology of Yorkshire’ is the same as the first.

Perisphinctes hiplex is, in England, generally considered to be the
zone-fossil of the Upper Kimeridge Clay, Damon’s figure * having
apparently been taken as the type instead of Sowerby’s.’ Dr. Siemi-

radzki devotes two pages of his monograph to it, and gives a figure
of the original bzplex, which is preserved in the British Museum
(Natural History). Unfortunately, he had only a plaster-cast on

1 *Monographische Beschreibung der Ammonitengattung Perisphinetes’
Palxontographica, vol. xlv (1898) p. “249,
* Ibid. pl. xxv, fig. 45.
3 «‘Tustrations of the Geology of Yorkshire’ 3rd ed. vol. i (1874) p. 325.
. ‘ Geology of Weymouth ’ Suppl. 2nd ed. (1880) pl. ix, fig. 9.
‘Mineral Conchology’ vol. iti (1821) pl. cexciii, figs. 1&2.
© Palzontographica, vol. xlv (1898) pp. 265-67.

Vol. 60. | UPPER JURASSIC AMMONITES. 55

‘which to base his conclusions, and a cast of so extraordinary a
specimen could hardly fail to be misleading. He ignores Peri-
sphinetes variocostatus (Buckland), but this I believe to be the species
which he means by P. biplewx, or at least a variety of it. The real
biplex, 1 venture to suggest, should be set aside as a freak.

Under these circumstances, it seems desirable to refigure and
redescribe Sowerby’s ‘types’ P. plicatilis and P. biplea, also Buck-
land’s P. variocostatus, and a specimen of the ammonite which has
so long been known in England (but not on the Continent’) as
Ammonites biplev, namely, Olcostephanus Pallasianus (d’Orb.).

The synonymy given here does not profess to be complete.

PERISPHINCTES PLICATILIs (Sow.). (Pl. IX, figs. 1 & 2 & text-fig. 1.)
[The ‘ type -specimen. |
. 1818. Ammonites plicatilis, Sow. ‘ Mineral Conchology’ vol. ii, pl. clxvi.
1880. Do. do. do. Damon, ‘Geology of Weymouth’ Suppl. 2nd ed.
pl. xvu, fig. 3.

Description.—tThe cast only is preserved. It is discoidal and
compressed. The sides of the whorls are flattened; the back
rounded; the cross-section is really
oblong, but it has a squarish ap-
pearance (Pl. IX, fig. 2) owing to
the weathering having followed the
backward slope of the suspensive
lobe. There are seventy fine ribs on
the last whorl; they are directed
slightly forward, and fork as they
pass over on to the back ; occasion-
ally they trifurcate, and still more
rarely they remain simple. The
back of the specimen is so much
worn that the ribs appear to have
been interrupted, and in places the
siphuncle even is exposed. There
are very faint indications of about
twelve constrictions, but they are so faint that I should scarcely
have noticed them had they not been more distinct in another
specimen, which differs from the ‘type’ in having (1) one auxiliary
lobe less, (2) fifty-four ribs at a diameter of 96 millimetres instead
of sixty-eight, and (3) the body-chamber preserved. The last-named
occupies nearly four-fifths of the last whorl.

- The suture-line (fig. 1, above) is very complex, the suspensive lobe
running back farther than either the first lateral or the siphonal.

Dimensions :—
Diameter = 107-2 millimetres; $4 milli- | Thickness of the last whorl = 0:268

Fig. 1.—Suture-line of Peri-
sphinctes plicatilis, nat.
size.

metres. | of the diameter.
Height of the last whorl = 0°321 of the | Width of the umbilicus=0°431 of the
diameter ; 0°359 of the diameter. | diameter; 0°396 of the diameter.

‘ See A. Pavlow, Bull. Soc. Imp. des Nat. Moscou, ser. 2, vol. iii (1889) p. 96;
also J. von Siemiradzki, Palzontographica, vol. xlv (1898) p. 267.

56 MISS MAUD HEALEY ON [Feb. 1904,

Many figures and descriptions of the changes which P. plicatilis
undergoes as it grows bigger have been published ; but as I have not
yet seen the form which I should feel justified in calling the adult
of this species, I must for the present content myself with a de-
scription of the ‘ type -specimen.

Locality and Stratigraphical Position.—Unfortunately,
no precise record of the locality whence this ‘type’ came has been
preserved. Sowerby contented himself with the indefinite state-
ment that it is found in a
‘sandy stratum containing beds ef sandy limestone at Dry Sandford and
Marcham, N.W. of Abingdon.’ !

It is, however, undoubtedly an Upper Corallian form, and is usually
taken as the zone-fossil of that horizon.

Affinities and Differences.—Ammonites plicatilis, as figured
by Alcide d@’Orbigny,* is more evolute and more compressed than
the type, while his figures on pl. exci are Perisphinctes biplew accord-
ing to Dr. Siemiradzki, that is, P. variocostatus (Buckl.). Dr. Siemi-
radzki regards Am. biplex as figured by d’Orbigny,’ and P. plicatilis
as represented by Waagen,* as synonymous with P. orientalis, Siem.
They differ from Sowerby’s ‘type’ plicatilis in being more evolute
and more compressed, but they are much nearer to it than the
figures in ‘ Paléontologie Francaise.’ A.de Riaz® takes d’Orbigny’s
fig. 1, pl. excii, as the type, aud consequently the specimen that he
regards as typical® is more evolute and slightly more compressed
than the real plicatilis: it is also distinguished by fewer and more
pronounced constrictions. De Riaz further states that he agrees with
Favre in his interpretation of this species; but the latter’s figures”
appear to me to be quite different, inasmuch as they have rounder
whorls, and their ribs are stronger, fewer in number, and bifurcate
sooner. De Riaz does note the last point.

Perisphinctes Martelli, Oppel, approaches our ‘ type’ very closely.
I am accepting Dr. Siemiradzki’s* views on P. Martelli, as he is
acquainted with Oppel’s original specimens. He takes fig. 3, pl. lv,
of Waagen (op. cit.), as representing it, and puts pl. exci, d’Orb. Pal.
Franc., Ter. Jur. vol. i (which Oppel” quotes as the ‘type’ of his
species), with P. biplex (Sow.). The suture-line which he delineates
differs from that of P. plicatilis (Sow.) in the character of the
terminal branches of the siphonal lobe, and in having one auxiliary

‘ Mineral Conchology’ vol. ii (1818) p. 149.
Pal. Franc. ‘ Terrains Jurassiques’ vol. i (1849) pl. excii, figs. 1 & 2.
Murchison, De Verneuil, & Keyserling, ‘Géologie de la Russie d'Europe &
des Montagnes d’Oural’ vol. ii (1845) pl. xxxvii, figs. 3 & 4.

* Mem. Geol. Surv. India, Palxontologia Indica, ser. ix, ‘ Jurassic Cephalo-
poda of Kutch’ vol. i (1875) pl. li, figs. 2@ & 2b.

° ‘Description des Ammonites des Couches a Peltoceras transversarium
(Oxfordien supérieur) de Trept (Isére)’ Lyons—Paris, folio, 1898, p. 10.

© Ibid. pl. iii, fig. 1.

* Mém. Soe. Pal. Suisse, vol. ii (1875) ‘ Description des Fossiles du Terrain
jurassique de la Montagne des Voirons’ pl. iii, figs. 1-3.

* Palzontographica, vol. xlv (1898) p. 267.

° Paleontologische Mittheilungen aus dem Museum des kgl.-bayerischen
Staates: ‘ Ueber jurassische Ammoniten’ 1862, p. 247.

1
2

3

yr -_
Vol. 60. ] UPPER JURASSIC AMMONITES. 57

lobe less. Waagen’s Martelli’ is only distinguished from plicatilis
by having fewer ribs. I very much doubt the specific value of this
distinction. P. Dunikowshii, Siem.* includes P. chloroolithicus,
Giimb., as figured by Waagen.’ Its whorls are slightly more com-
pressed than those of plicatilis, which is therefore intermediate
between it and Martelli, having the ribs of the former and the cross-
section of the latter. Am. Schilli, Oppel,* is distinguished by the
slope of its sides towards the back being much greater. It is also
slightly too involute and the second lateral saddle is different.

I do not propose to enter into the question as to how many of
these are good species, but some of them, I think, might with great
advantage be reduced to the rank of varieties.

Remarks.—This specimen is in the Buckland Collection, in the
University Museum, Oxford. It bore no label, but no one who has
compared it with Sowerby’s original figure can doubt its identity.
Sowerby’s figure is reversed, and somewhat restored: hence the
slight differences between it and a photograph of the specimen.

PERISPHINCTES BIPLEX (Sow.). (VI. X, figs. 1 & 2.) [The ‘type ’-
specimen. |

1821. Salata bipler, Sowerby, ‘Mineral Conchology’ vol. ii, pl. ccxcin,

Description.—In the first place, it is necessary to remark
that Sowerby’s two figures do not represent parts of the same
specimen, as Dr. Siemiradzki believed them to do. The smaller
(loc. cit. fig. 2) is a fragment of a cast in dark, bluish clay, with
traces of a nacreous shell still adhering to it, and may be dismissed
from our consideration at once. The larger (Joc. cit. fig. 1) looks
as though it had come out of a septarian nodule, probably from the
Kimeridge Clay. Sowerby obtained it from the Drift of Suffolk.’
It is preserved in calcite and pyrites, except the body-chamber,
which is filled with a somewhat hard, yellowish, compact matrix,
and occupies about three-quarters of the last whorl. The whole
shell is somewhat distorted. The cross-section of the inner whorls
is broader than high, but as the shell grows older this is reversed.
There are fifty ribs at a diameter of 100 millimetres. They run
slightly forward, and bifurcate just as they pass over on to the back ;
one trifurcates, and one remains simple until it reaches the middle
of the back, where it unites with both branches of the opposite rib.
The suture-line is but partly visible here and there.

The shell is broken across along the line QR (Pl. X, fig. 1)
which does not pass through the centre, and when the two parts
are put together they form what appears to be an ordinary ammo-
nite; but the cross-section (Pl. X, fig. 2) shows that this is far

1 «Jurassic Cephalopoda of Kutch’ vol. i (1875) pl. ly, figs. 3a & 3.0.
2 Paleontographica, vol. xlv (1898) p. 269.

3 «Jurassic Cephalopoda of Kutch’ vol. i (1875) pl. 1, figs. 3a & 3d.
4 ry

5

‘Jurassische Ammoniten’ [atlas] 1862, pl. Ixv, figs. 7a & 7 b.
‘ Mineral Conchology ’ vol. iii (1821) p. 168.

58 MISS MAUD HEALEY ON (Feb. 1904,

from being the case. For convenience of description, I have called
one surface A, the other B. Fig. 1 represents the B surface. On
surface A all the inner whorls are perfect; on B also they are
perfect, down to an umbilical diameter of 16 millimetres, that is
to the point O in fig. 2. On side A of the cross-section there is
revealed a small, perfect ammonite, which can be traced to a
diameter of 46 millimetres, after which it is lost in a whorl the
sides of which are those of both the A and B surfaces, the shell
having here attained a diameter of 50 millimetres. The centres of
the two surfaces correspond, and so do the inner whorls. The
back of the little ammonite shows bifurcating ribs. It does not
seem possible that it could have been forced into its present posi-
tion by extraneous means, for neither the A nor the B surface shows
signs of disturbance in the inner whorls. On the other hand, it
is very difficult to imagine it growing in its present position.

Remarks,—I have already indicated the probability of Peri-
sphinctes biplex being a Kimeridgian form, but the horizon whence
it came must remain doubtful. In cases like this, it is perhaps
wisest to abandon the name altogether, or at least to restrict it
to the abnormal specimen to which it was first attached.

I have not given dimensions, because no reliance can be placed
on them in such eases.

The specimen is in the British Museum (Natural History).

PrrIsPHINCTES vaRrocosratus (Buckland). (Pl. XI, & text-fig. 2.)
[The ‘type ’-specimen. |

1836. een variocostatus, Buckland, ‘ Bridgewater Treatise’ (no. 6) pl. xii,
1898. ee iaanies biplew, Siemiradzki, Paleontographica, vol. xlv, ‘ Mono-
graphische Beschreibung der Ammonitengattung Perisphinctes’ p. 265.
Description.—The shell is large and discoidal. The whorls
are about as high as
thick, and are orna-
mented with strong
ribs, directed slightly
forward and_ bifur-
cating with perfect
regularity as they
pass over on to the
back. At adiameter
of some 180 milli-
metres the whorls be-
come depressed, and
at the same time the
ribs become farther
apart, cease to bifur-
cate, and begin to develop wedge-shaped swellings. At a diameter
of 183 millimetres there are fifty-five ribs, and at 100 or thereabouts
(for the outer whorls prevent accurate measurements) fifty-three.
The suture-line delineated in fig. 2 (above) is restored. This was

Fig. 2.—Suture-line of Perisphinctes vario-
costatus, restored. Nat. size.

Vol. 60.] ° UPPER JURASSIC AMMONITES. a9

necessary, because the suture-line, where fully exposed, is too much
simplified by weathering to be reliable.
“A small portion of the body-chamber is preserved.

Dimensions :—

Diameter = 183 millimetres ; 215 milli- | Thickness of the last whorl=0°289 of

metres. the diameter; 0-294 of the diameter.
Height of the last whorl = 0°262 of the | Width of the umbilicus=0'502 of the
diameter ; 0°274 of the diameter. diameter ; 0°504 of the diameter.

The measurements of the height and thickness of the last whorl
are not very accurate, as the shell is absent in places and the cast
is worn.

Locality and Stratigraphical Position.—Buckland states
that this specimen came from the Oxford Clay at Hawnes,
4 miles south of Bedford, but I am of opinion that it came from
the Ampthill Clay, and for the following reasons :—

1. It is distinctively Corallian in appearance.

2. Hawnes is only 3 miles north-east of Ampthill, and is near
the edge of the band of colour indicating Lower Greensand on the
Geological-Survey maps. Further, the Geological Surveyors’ say
that

‘traced beyond Ampthill the boundary of the Oxford and Kimeridge Clays is
largely concealed for some distance by the Cretaceous rocks.’

3. It is not pyritized, and T. Roberts’ remarks that in the
Ampthill Clay

‘|fossils] are never pyritized, and on this account the clay is easily distin-
guished frum the underlying Oxford Clay,’

Affinities and Differences.—Perisphinctes variocostatus
differs from Siemiradzki’s interpretation of P. biplex (Sow.) in the
following details :—

1. It has never more than fifty-five to fifty-seven ribs to a
whorl, while P. biplex has seventy in middle-sized whorls,’ but at
a diameter of 100 millimetres it has fifty-three as against fifty.

2. Its innermost whorls are slightly more evolute.

The dimensions are practically the same, and the change in the
character of the ribs occurs in both at a diameter of about
200 millimetres. As to the suture-line, Dr. Siemiradzki speaks
doubtfully of that given by A. d’Orbigny* as belonging to his
biplex. It has a shorter auxiliary lobe than varvocostatus.

The dimensions of P. torqguatus, Sow., as tabulated by Dr. Siemi-
radzki,’ for a diameter of 157 millimetres, are exactly those of
P. variocostatus at 183 mm. ; but in other respects the two are quite

1 H. B. Woodward, Mem. Geol. Surv. ‘ The Jurassic Rocks of Britain’ vol. v
(1895) p. 138.

* «The Jurassic Rocks of the Neighbourhood of Cambridge’ 1892, p. 36.
[Sedgwick Prize Essay for 1886. |

* Siemiradzki, Paleontographica, vol. xlv (1898) p. 266.

* Paléontologie Francaise ‘ Terrains Jurassiques’ vol. i (1849) pl. exci.

° Paleontographica, vol. xlv (1898) p. 264.

60 MISS MAUD HEALEY ON [Feb. 1904,

distinct. Sowerby’s ‘type’ is a small specimen from Cutch'; but
Waagen? figures one 210 millimetres in diameter, and this shows
that the ribs do not change nearly so soon as in variocostatus, that
the back remains rounder, and that the ribs frequently trifurcate.

P. variocostatus has fewer and thicker ribs than P. Martelli or
plcatilis, and the suspensive lobe runs back at a greater angle.

P. chloroolithicus and P. Vaydelota are more compressed and more
evolute.

Remarks.—This specimen is in the Buckland Collection, in the
University Museum, Oxford. ‘ Hawnes, Bedford,’ is written in ink
on it, and it bears fragments of an old label on which ‘ Hawnes..
va’... is still legible, in the same handwriting as that found on
most of Buckland’s labels. It corresponds exactly with Buckland’s
detailed description ° and with his figure,’ although the latter is too
much reduced to be of great value.

OxcostePHANUs PaLLastanus (d’Orb.), var.noy. (PI. XII, figs. 1 & 2,
& text-fig. 3.)
1845. Ammonites Pallasianus, VOrb., Murchison, De Verneuil, & Keyserlng,
‘Géologie de la Russie d’Europe & des Montagnes d’Oural’ vol. ii, pl. xxxu,
figs 1-3.
1864. A. kimmeridiensis, K. von Seebach, ‘Der Hannoversche Jura’ Berlin, p. 157.
1873. A. biplea (Sow.), P. de Loriol et Pellat, ‘ Monographie paléontologique &
géologique des Etages supérieurs de la Formation jurassique des Environs
de Boulogne-sur-Mer’ Mém. Soc. Phys. Hist. Nat. Genéve, vol. xxi,
p. 269 & pl. u, figs. la-1b. f
1880. A. biplea (Sow.), Damon, ‘ Geology of Weymouth’ Suppl. 2nd ed. pl. ix,
g. 9.
1871. A. biplex (Sow.), Phillips, ‘ Geology of Oxford & the Valley of the Thames ’
p. 333 & pl. xv, fig. 17.
1895. A. biplex (Sow.), Mem. Geol. Surv. ‘Jurassic Rocks of Britain’ vol. v,
fig. 72, p. 156.
Description.—Only minute fragments of the actual shell are
preserved. The cast is discoidal; the
Fig. 3.—Suture-line of whorls rounded and somewhat depressed ;
Oleostephanus Pal- the ribs sharp and prominent, about 31 in
lasianus, var. nov, Number; all but three bifurcate as they
Wahoos pass over on to the back; these three re-
Ly main simple, and, judging from analogy
with other specimens, would each be pre-
ceded by a constriction if the shell were
preserved. The body-chamber occupies
nine-tenths of the last whorl.
Remarks.—I have identified this specimen with d’Orbigny’s
figure (loc. supra cit.) with some hesitation, caused chiefly by the
cross-section of the whorls, which is more depressed, and by the
number of the ribs, d’Orbigny’s figure showing only twenty-six,
of which six are simple. The suture-line also is slightly different.

WAY
TY

Nee

Trans. Geol. Soc. ser. 2, vol. v (1840) pl. Ixi, fig. 12.
‘Jurassic Cephalopoda of Kutch’ vol. i (1875) pl. liv.
‘ Bridgewater Treatise’ No. 6, vol. ii (1836) p. 62. 4 Ibid. pl. xhi, fig. 7.

eo

Quart. JouRN. GEOL. Soc., VoL. LX, PL. IX.

Fie 1. NAT. SIZE.

Fie. 2. NAT. SIZE.

+

a

Bemrose Litd., Collo.

PERISPHINCTES PLICATILIS (Sow.).

Sad

Biker aaah
Pa Poe

PL. x:

Quart. JOURN. GEOL. Soc., VoL. LX,

Bemrose Litd., Collo.

PERISPHINCTES BIPLEX (Sow.).

Vol.60.j | LAKE-BASINS BETWEEN THE JURA AND THE ALPS. 695i

6. The Ace of the Principat Laxn-Basins between the Jura and the
Ars. By C. 8S. Du Ricus Pretrur, M.A., Ph.D., A.M.I.C.E
M.L.E.E., F.R.S.E., F.G.8. (Read April 29th, 1903.)

[ Abstract. |

1. In a paper read before the Society in 1902,’ the Author
showed, on the evidence of extensive high-level deposits of Decken-
schotter in Subalpine France and Switzerland, that the principal
Swiss lake-basins could not have existed at the time when those
deposits were formed, during and after the first or Pliocene glaciation
of the Alps. In the present paper he deals with the question
reserved in the preceding one, that is, to which subsequent period
the formation of those lake-basins should be assigned. By the
light of further recent investigations in the different localities, he
first considers the conditions of the Zurich lake-valley, where the
successive glacial and fluviatile deposits are clearly defined, and
then applies his conclusions to the other principal lake-basins
lying in the same zone along the edge of the Alps.

2. The hitherto generally-accepted view that the lake-basins are
pre-Glacial in the old sense, or were formed during the first inter-
Glacial period, rests, in the main, on two arguments: (1) that the
alluvia at the lower ends of the lakes are all Glacial, not only from
their appearance, but because the materials composing them could
only have been transported thence by glaciers, which either passed
over the lakes by bridging them, or through them by completely
filling them with ice; and (2) that the zonal bending of the
Molasse along the edge of the Alps, to which the lake-basins owe
their existence, occurred before the second or maximum glaciation,
because on the hills flanking the Lake of Zurich the younger
moraine-banks are undisturbed: and, further, because at a point
in the Lorze ravine (near the Lake of Zug) the Deckenschotter
conglomerate dips reversely, that is, up the valley, while the over-
lying, younger, loose gravel dips in the opposite direction.

3. ‘The Author adduces evidence to show that the deep-level
gravel-beds in the Limmat Valley near and below Zurich are
essentially fluviatile, composed of the characteristic Alpine material
of the Rhine and Linth drainage-areas, and in all other respects
similar to the gravel carried by the River Sihl at the present day.
These gravel-beds rest upon Glacial clay of the second glaciation,
which fills the Molasse-bed of the valley to a great depth, and are
overlain by the moraine-bars and secondary products of the third
glaciation, the latter being overlain by, and mixed with, the post-
Glacial alluvia of the Sihl.

4, He further argues that it is, on mechanical grounds, difficult

? Quart. Journ. Geol. Soe. vol. lviii (1902) p. 450.
G.3,6.8. No. 237. F

66 DR. DU RICHE PRELLER ON THE AGE OF THE [| Feb. 1904,

to conceive how glaciers could either bridge, or completely fill with
ice, basins so extensive as those of the principal Alpine lakes, from
2 to 8 miles in width and from 470 to 1020 feet in depth, the
quantity of water to be displaced and expelled in the individual
cases ranging from 3500 million to 90,000 million cubic metres or
tons.

5. As regards the more recently-advanced argument of the
younger moraine-banks flanking the Lake of Zurich and of the
Deckenschotter in the Lorze Valley near Zug, the Author points
out that it is not borne out by the evidence on the ground, and
that, apart from the difficulty of differentiating the second and
third glaciation-materials in both localities, it is obviously hazardous
to deduce from purely-local phenomena of this kind the date of the
zonal bending affecting six valley-systems, and extending over more
than 200 miles along the edge of the Alps.

6. The Author’s investigations point to the conclusion that the
deep-level Limmat gravel-beds, overlain by the moraine-bars of
the third glaciation, were deposited by a river during the second
inter-Glacial period; that the lowering of the valley-floor was
initiated in the course of the third glaciation, probably when the
glacier had already reached its maximum extension, about 10 miles
below Zurich ; that the zonal subsidence continued throughout the
retreat of the ice; and that the simultaneous formation of the lake-
basin should, therefore, be assigned to the end of the Glacial Period,
after which the original basin was, notably at its upper end,
restricted to its present dimensions by post-Glacial alluvia.

7. In conclusion, the Author shows that the same arguments
apply, in the main, also to the origin and age of the other principal
zonal lake-basins, which he illustrates by longitudinal sections. In
his view, the position and depth of these basins, as well as the
intervening ground, point to the probability that the bending took
place not only along one line, but along several, more or less
parallel, not always continuous lines within the zone between the
Alps and the Jura; that the bending was by no means of uniform
depth ; and that, therefore, the Alps did not subside as a rigid mass,
but that the zonal bending along their edge merely extended
locally for some distance from the deepest points of the lake-basins
along the floors of the principal Alpine river-valleys.

Discussion.

Prof. Bonnry said that he had always felt great difficulty in
understanding how the glaciers made their way through the lake-
basins, supposing these to have been in existence at the time of the
great glaciation. But what had most impressed him was the fact
that the Zurich gravels were true river-gravels, and quite different
from deposits formed in proximity to a glacier. Of this difference
he gave details, pointing out that a stone must travel not a few
miles (much longer than the distance determined experimentally
by Daubrée) in order to become well rounded. So that neither the

Vol.60.] | LAKE-BASINS BETWEEN THE JURA AND THE ALPS. 67

Deckenschotter nor the Zurich gravels (and the same was true else-
where) could have been formed in the neighbourhood of a glacier.
He had always attributed the Alpine lakes to zonal bending, and had
long thought that there were at least two lines on the north side ;
but he was inclined to believe that there might have been slight
subsidence along the watershed of the Alps, as the higher parts of
the Alpine Rhine and Rhone valleys seemed now to be filling up.
Prof. Garwoop, in reply to a question asked by the Author, stated
that he did not think that the Fairhaven glaciers in Spitsbergen,
quoted by Martins, affected the point at issue: the observation
probably referred to an overhanging advance of the upper layers of
the ice, so common in that district; and he could hardly believe that
any of the Swiss geologists seriously suggested that a glacier could
traverse a large lake-basin in the manner indicated by the Author,
by clinging merely by its borders, and pass through unsupported in
the middle. He was interested to hear that the Author attributed
the formation of these large Swiss lakes to a time posterior to the
maximum glaciation of the Alps, on the strength of the fluviatile
character of the deposits described from theirlower end; but, what he
would specially like to know, was the age of the valleys in which the
lakes occurred. A similar problem of the origin of the Italian lakes
had occupied his attention for some years, and he did not think that a
local subsidence could alone account for these lakes on the south side
of the Alps. The Lake of Como was an especially difficult problem,
as it not only ran at right angles both to the axis of the Alps and the
strike of the limestones, but also exhibited a reversed drainage of a
very peculiar character. Why did the drainage flow from Como to
Lecco? What river or glacier-system could be pointed to at the
present day, which, after flewing as a trunk-stream, divided into two
deep branches, as must have been the case if the present drainage
of the Lake of Como represented the original direction of flow of the
valleys? It had often occurred to him that the rivers might once
have flowed northward, and not southward. It was a curious fact
that so many of the lake-branches came in from the south; and
Lugano, which is 100 feet higher than Como, might very easily have
entered as a tributary of the latter lake at Menaggio. The difficulty
in the way was the range of the Spliigen Alps. Mr. Marr had once
suggested that this uplift might have taken place since the formation
of the old valley-systems now occupied by the lakes: this would throw
back the date of these valleys to Miocene times. He had collected
for some time from the deposits of the Righi district with this idea
in his mind, but without any definite result. The more, however,
that he saw of the district, the more was he convinced of the great
age of the valleys, and the probability of the reversal of the original
direction of their drainage. He thought that the many areas of
special subsidence required by the Author for all the Swiss lakes
would require some definite proof in each case. He was glad to
find that the Author did not include direct glacial erosion among
the possible modes of origin for the lakes; although it must be
remembered that quite recently an eminent American geologist had
F2

68 THE AGE OF THE PRINCIPAL [ Feb. 1904,

stated his conviction that the Lago Maggiore was entirely due to
excavation by the Ticino Glacier during the Glacial Period.

The Rey. E. Hitt said that he could not follow the Author’s
argument against ice-filled basins, but agreed with his conclusions.
The gravels below the lakes were the proofs. A lake was a barrier
to gravel-transport more effectual than a strait to quadrupeds ; and
in a time of ice-filled basins the precipitation, chiefly in snow,
would be unfavourable to pebble-manufacture. He asked whether
there were traces of submerged channels in the lakes. Such
would be almost conclusive in favour of the Author’s views.

Dr. J. W. Evans asked whether the Author considered that the
sites of the lakes were still actually covered with ice when the
depression occurred which caused their formation; and suggested
that the cessation of river-action—as a result of great cold or
deficiency in rainfall—was a necessary condition of the origination
of lakes by earth-movements, except when such movements were
unusually rapid.

Mr. Wuiraxer enquired whether any further proofs were
available, beyond those adduced by the Author, in regard to
the fluviatile origin of the gravels. He pointed out that, in
many British river-gravels, remains of terrestrial or freshwater
organisms were occasionally found; and, if such could be obtained
from the Swiss gravels, the discovery would strengthen the
Author’s argument.

Dr. Jack asked whether the gravels in the lower portions of the
lakes, which had been referred to as fluviatile, might not be re-
arranged gravel from cones of dejection brought down by lateral
streams, subsequently to the erosion of the lakes. He confessed
that he was much surprised to hear the Author (as he understood
him) deny the former greater extension of the lakes. very lake
that he had ever seen was obviously and visibly shrinking, and it was
only a question of time when every lake on earth would be silted up.
He admitted that lakes formed ‘ cataclysmically ’ are comparatively
rare, but not unknown, even in modern times: for example, he had
seen a good many lakes which were formed in the Tarawera district
of New Zealand, during the eruption of a few years ago. One
occupied the site of the tamous ‘ pink and white terraces.’

The AvtHor, in taanking the Fellows for the kind reception
accorded to his paper, observed, in reply, that Prof. Bonney had
examined the Limmat gravel-beds with him in 1896, and had ever
since taken a kind and keen interest in the subject, and that conse-
quently his concurrence in the conclusions arrived at in the paper
was of great value, both as to the age of the lakes and the system of
flexures which produced them. Prof. Garwood’s interesting and
welcome explanation of a Spitsbergen glacier bridging the sea
(quoted by Martins in 1845) reduced that phenomenon to its true pro-
portions, namely to a probable simple overhang of the upper layers
of the glacier. With regard to the Italian lakes, he (the Author),
although knowing them well, had not yet examined them in detail,,
and therefore could not as yet express an opinion as to their age and

Vol. 6o. | LAKE-BASINS BETWEEN THE JURA AND THE ALPS. 69

origin, although there was a prima-facie presumption of these, too,
being the resuit of a lowering of their former river-floors by flexures.
In reply to Mr. Hill, he said that there were channels of consider-
able length and depth at the upper ends of the Lakes of Constance
and Geneva. With regard to Dr. Evans’s remarks, the lakes being
formed during the retreat of the ice, it followed that the glaciers
were probably still melting in the basins as these were forming
by a lowering of the floors. In reply to Dr. Jack, he said that
the only lateral torrent to which the deep-level Limmat gravel-beds
could be due (if not to the main river) was the river Sihl, the alluvium
of which was, however, entirely post-Glacial and superficial. He by
no means denied the possibility of a former, greater extension,
and, consequently, of higher levels of the lakes; but averred that
direct evidence was necessary to prove it in individual cases, for
an alluvial plain might also be formed by a meandering river. In
answer to Mr. Whitaker’s question, he said that the only fluviatile
deposits of the Glacial Period in which, to his (the Author’s)
knowledge, fossils had been found, were those of the Upper
Pliocene Deckenschotter, or alluvion ancienne, near Lyons;
while the younger inter-Glacial gravel-alluvia contained few, if any ;
but that he had reason to believe that confirmatory evidence—if
such were wanted—of the age of the deep-level Limmat gravel-
beds (second inter-Glacial period) near Zurich would be found in a
similar sequence of deposits in the Rhéne Valley near Geneva, with
which he proposed to deal on a future occasion.

70 MR. E, E, WALKER ON THE GARNET-BEARING [Feb. 1904,

7. NorEs on the Garnet-BEarinc and AssociateD Rocks of the
BorrowpaLE Votcanic Series. By the late Epwarp Eaton
Watker, B.A., B.Sc., Scholar of Trinity College, Cambridge,
Geologist to the British East-Africa Protectorate. (Commu-
nicated by J. E. Marr, Esq., M.A., F.BR.S., F.G.S. Read
December 2nd, 1903.)?

[Pirates XIII & XIV—Mzicroscore-Sections. |

TABLE OF CONTENTS.

Page
I. The Intrusive Complex of Blea Crag, Langstrath ................ Riya
TL. Jnteusions inthe Bow-F ell. Distrieg 22. -2..2.- 6 ceeee ee eee 76
III. Basic Offshoots from the Eskdale Granite ............2.............. 7
IV. The Intrusive Complex of Burtness Combe, Buttermere ......... 83
V. Other Garnetiferous Intrusions in the Lake District ............... 85
VI. Garnetiferous Rocks in the Faleon-Crag Andesite-Group ......... 86
VII. The ‘ Streaky’ Rocks of the Central Mountain-District ... ..... 89
Viti.“The* Streaky ’ Rocks of the Haweswater District: .................. 98
LX. The‘ Characters of the 'Garnets \/2....., sf Skeet ee a 101
X. Metamorphism of the Volcanic Rocks ..................c0.00+0 yates 102

I. Tue Iyrrusive Compiex oF Brea Crac, Lanesrrate.

Durine the past year I have spent the greater part of my vacations
in the study of the garnet-bearing rocks associated with the
Borrowdale Voleanic Series. Being unable to proceed further with
this work, | venture to put forward the results of my observations,
in the hope that they may be of use to those who continue the
study of these rocks. I should like, at the outset, to say how
greatly indebted I am to Mr. Marr for all the help that he has given
me; he has not only placed at my disposal his own maps of the .
area and the details of his own observations, but has always been
ready with encouragement and advice. My thanks are also due to
Mr. Harker for the kind help and advice that he has given me
during the progress of the work.

? [The manuscript of this paper was placed in my hands by Mr. Walker when
he left for Africa early in 1902, the work having been largely done in 1901. I
was requested to keep the MS. and not to communicate it to the Society,
unless it was certain that the Author could not continue the work, for he had
hoped, on his return to England, to prosecute his researches among these rocks,
especially by completing the chemical analyses, which were only partially
carried out. His sad death, occurring but a year after he went out, has
deprived our science of a most promising student, of whom his friends ex-
pected great things, and I feel that the paper, which I now have the honour of
communicating to the Society, furnishes no mean evidence of Walker’s powers.
Although the work is incomplete, it will certainly be of great value to
those interested in Lake-District geology, and also to students of the remark-
able and exceptional type of rock which is therein described.— J. E. M.,
October 1903. |

Vol. 60.| ROCKS OF THE BORROWDALE VOLCANIC SERIES. 71

The Volcanic Series runs in a broad belt, 12 or 13 miles
wide, across Cumberland and Westmorland. In order to become
acquainted with the various features of the garnetiferous rocks, I
have attempted to cover some 130 square miles of ground; and as
the greater part of this area has only been visited once, I feel some
diffidence in drawing any conclusions from so hurried a survey.

Perhaps the most interesting of these garnet-bearing rocks are
those which occur as dykes and sills intrusive in the Volcanic Series.
They are chiefly to be found in the central part of the district, in
connection with the large intrusive masses of the Eskdale Granite
and the Ennerdale Granophyre.

The most typical of these minor intrusions is to be seen in the
Langstrath Valley (75° N.W.) at and around Blea Crag. Clifton
Ward mapped this as a small laccolite: if such be the case, it is of
very irregular form, for on the west side of the valley the branches
often run at right angles to the strike of the surrounding rocks.
Ward described the rock as a diabase with felsite-veins ; there
seems, however, to be an almost infinite variety of rock, from avery
fine-grained black, through a coarse parphyritic dark-green rock, to
one containing quartz and pink felspar.

I made an attempt to put in the dividing-lines between these
various types, but found that, except for small areas, this was im-
possible—the rocks varying in composition and texture every few
yards, and shading gradually one into the other.

Some very good junctions are, however, seen in a small exposure
north-north-west of Blea Crag, and separated from it by two small
streams. This little section was visited by the members of the
Geologists’ Association in August 1900. The lines of the junc-
tion are here seen to be very sharp—the fine-grained black rock
weathering with a smooth, and the coarse rock with a pitted
surface. Where the broken lines occur in fig. 1 (p. 72) no distinct
junction is seen, but the two types shade one into the other and
give rise to a dark-green porphyritic rock. Near the junction of
the two the coarse pink rock is found with greenish aggregates,
representing, no doubt, portions of the fine-grained rock which
have been absorbed and have become more crystalline in the
process. It is possible to obtain a perfectly-gradual transition
from the fine-grained black rock, through a dark-green to the
coarse pink rock, in a single hand-specimen.

Good junctions are also seen below Blea Crag itself, where the
fine-grained rock is plastered against the coarse, and is penetrated
by veins of the latter. The junction may be followed up the
southern face of the Crag, but it is lost above.

From these sections it is evident that the fine-grained rock was
first intruded, followed by the more acid rock. The interval
between the two periods of intrusion must have been short, for the
two types have intermixed to form an intermediate one. We
have here, then, a case of the intrusion of the basic and acid portions
of an already-differentiated magma, and by the intermixture of the
two extremes intermediate types have been produced. In the face

(2 MR. E, E, WALKER ON THE GARNET-BEARING [ Feb. 1904;

of Blea Crag an intermediate rock is cut by a more acid rock—the
junctions being well defined; so it is probable that there were succes-
sive periods of intrusion and intermixture. That differentiation
went on almost simultaneously with intrusion, is well shown
by a specimen obtained from the summit of Blea Crag, in which
the black fine-grained rock encloses completely a portion of coarse
pink rock, the latter being an acid segregation. Naturally, under
these circumstances, xenoliths are exceedingly abundant and of
great. variety. Usually the xenolith is more basic than the
enclosing mass, but the reverse also occurs.

Fig. 1.—Diagrammatic sketch of an exposure north-north-west of
Blea Crag, Langstrath.

~

c.

a
a
a
i
i
a
a
a
f
YD
/

F = Fine-grained black rock.
C = Coarse pink rock.
C'= The same, with pink felspars.

G = Dark-green porphyritic rock,
with greenish-white porphy-
ritic felspars.

| <X>= 13 yards.

The dark fine-grained rock bears a very great resemblance to the
dark-green fine ash into which these rocks are intruded; and, so
far as it is possible to judge, Ward mapped this rock as an ash.

A section (3750)! across the specimen mentioned above shows
that the pink rock is a granophyre. The structure is entirely a
micropegmatitic intergrowth of quartz and orthoclase. Oblong
sections of turbid felspar are seen to be continuous with the
felspar of the intergrowth, but it is only these idiomorphic felspars
that are altered to white mica. Sometimes they show signs of
corrosion by the granophyric material. Garnet occurs in rounded
sections, ilmenite and chlorite occurring at the border as products
of its decomposition. Chlorite-scales are abundant throughout the

' The numbers in parentheses throughout this paper refer to the numbers
on the slides which are in the Sedgwick Museum, Cambridge.

Vol. 60.| | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 73

rock, frequently associated with a twinned muscovite. Pyrites
is common, in square sections giving a reddish transmitted light,
and is almost invariably surrounded by chlorite. Zircon occurs in
minute crystals, with the pyramid-planes developed.

Very little can be made out of the fine-grained rock. Chlorite-
flakes are scattered throughout; quartz, a few minute felspars
entirely altered to white mica, and aggregates of iron-ore also
occur in it. When this rock is taken up by the coarse rock of the
small exposure, it becomes dark-green and much more crys-
talline. A section across the two (3795) shows that the coarse
rock is @ basic granophyre, containing turbid phenocrysts of
plagioclase in a micropegmatitic groundmass. Colourless fragments
of augite-crystals occur, surrounded by a mixture of chlorite and cal-
cite produced from their decomposition. Apatite is fairly abundant.
The dark-green rock might be described as a quartz-diabase.
The same turbid felspar occurs sparingly as phenocrysts in a
matrix of plagioclase, quartz, and chlorite. Sometimes the chlorite-
patches enclose the felspar in ophitic relation. Iron-ore is more
abundant than in the coarser rock, but apatite less so.

Turning to the intermediate porphyritic types, we find
that the most basic (3752) contains quartz and felspar-phenocrysts,
with garnet and pyrites. The last-named mineral is very abundant,
and occurs in small cubes, surrounded by a zone of quartz which may
consist of radial flakes or of little grains. Garnet occurs in rounded
sections, much corroded and surrounded by a ring of plagioclase.
Pseudomorphs of chlorite and epidote after original biotite are
common. The epidote is usually developed in grains along the
cleavage. The groundmass consists of felspar-laths, quartz, and
pyrites. ;

The next type (38751: Pl. XIII, fig. 1) contains phenocrysts of a
felspar, probably an acid labradorite, enclosed by flakes of biotite.
Xenoliths consisting of altered felspar, hornblende, and ilmenite
occur, closely resembling the hornblende-porphyrite to be described
later. Large blebs of quartz are seen, much corroded, and conse-
quently surrounded by an aureole of a lighter colour than the rest
of the groundmass. A slide of this rock shows beautifully the
telspar-ring developed round a garnet. The garnet is much corroded,
and biotite occurs in the embayments; the whole garnet is sur-
rounded by plagioclase, with many prisms of apatite. Biotite is
often entirely decomposed to chlorite and iron-ore, lenticles of
calcite being developed occasionally along the cleavage.

Shde 3776 differs from the last-described in the greater proportion
of telspar-phenocrysts, of quartz in the groundmass, and the smaller
quantity of iron-ore. The felspars show albite and pericline-twin-
ning, with occasional well-marked zonary banding. Extinction-
angles point to andesine or oligoclase-andesine. Paragonite-mica
and possibly free quartz result from them; and in many cases the
crystals are completely transformed into these products, acquiring
at the same time a reddish tinge, which gives them the appearance

74 MR. E. E, WALKER ON THE GARNET-BEARING [ Feb. 1904,

of a pink orthoclase when the rock is viewed in bulk. Biotite
embraces, or hss a parallel arrangement with, the felspars, and
decomposes to chlorite and epidote. Apatite is most abundant
in this rock.

In the last three types the groundmass becomes gradually coarser,
and a gradual passage is traced from a quartz-garnet-
porphyrite with pyrites into a true granophyre. The
felspar, becoming more and more abundant, finally develops into
irregular masses and takes part in the micropegmatitic intergrowth.
Slide 3863 furnishes an example of such a granophyre, containing
aggregates of chlorite-flakes which represent original augite.

The most acid rock is seen on the precipitous face of Blea
Crag, and is also developed along the bed of Langstrath Beck, south
of the Stake Pass. It was mapped by Clifton Ward as an acid dyke,
and is undoubtedly connected with the Blea-Crag intrusive rocks,
for, like them, it shows perfect transition from fine-grained basic to
coarse acid reck. Under the microscope (5787: Pl. XIII, fig. 2)
it is seen to have a very characteristic appearance. ‘The felspar is
orthoclase, occurring either in idiomorphic oblong crystals, or in
irregular masses. It is invariably surrounded by a microspherulitic
growth of quartz and felspar. Quartz occurs in irregular blebs,
occupying the interspaces between the spherulitic growths—chlorite
nearly always accompanying it. In parallel arrangement with the
quartz- and felspar-fibres of the intergrowth, occur elongated flakes
of chlorite representing original biotite. Garnet is present in
rounded crystals much broken and corroded, and surrounded by
the spherulitic growth. We have here an association which points
to the early consolidation of the garnet from the molten mass.
Apatite occurs sparingly.

This rock varies somewhat in the relative proportions of the
constituent minerals; but, as a type, it is perhaps the most acid rock
met with in any great bulk. Xenoliths of more acid rocks do occur.
In Bull Crags a fragment of micropegmatite (3862) was found
containing quartz, orthoclase, plagioclase, and chlorite. The same
rock is to be seen in place as a dyke in Angle-Tarn Gill, immediately
above the little ravine.

A dark-green basic rock (3861), with abundant ferromagnesian
mineral, was found above Bull Crags. The ferromagnesian mineral
is hornblende, showing strong pleochroism, the colours being

brownish-green, brownish-green, yellow
c = b = a

The felspars are altered to white mica. Oval patches of quartz
with a nucleus of calcite may represent origiial vesicles. This rock
is a good hornblende-porphyrite.

A xenolith from the west side of Langstrath Beck (3566) shows
idiomorphic felspars with albite and Carlsbad twinning, and possibly
a microperthitic intergrowth. Small prisms of uralite, with multiple
twinning parallel to the orthopinacoid, occur with the same felspar

Vol.60.| | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 75

‘in the groundmass. Epidote is abundant, partly arising from
infiltration and partly from decomposition of original minerals.
This rock bears a strong resemblance to those found at Burtness
Combe, Buttermere.

Perhaps enough has been said to give some idea of the petro-
logical character of these rocks. Their chemical relationships are
not less interesting. I have made partial analyses of four pro-
minent types, and these are sufficient to show how closely allied
the rocks are one to the other. hese analyses were carried out
in the laboratory attached to the Mineralogical Museum, where, by
the kindness of Prof. Lewis and Dr. Hutchinson, every facility was
afforded to me for the work.

A. B. C. D.
Percent. Percent. Percent. Per cent.

eg ane cs a ganess an 57°91 60-02 61°63 64°40
TiO, |

i A ee 27°56 25°36 22°34 22°38
Fe,0, j

0 ee eee 0°52 0-29 0°22 0-14
0 > MS Se Renee 6°19 3°97 4:40 2-27
cj ee Pe ee 1:20 0-91 0-98 0-60
MIRE Eon actettet dents 1-82 2°55 4-04 579
UO) Sade ecb seat 1-64 2°62 2°51 2°51

Specific gravity ......... 2°856 at 13°8° C. — 2°748at 13°49. 2°722 at 16°1°.
A= Fine-grained black rock of Blea-Crag summit. Slide 3750.

B= Quartz-garnet-mica-porphyrite in stream above Blea Crag. Slide 3751.
C= Quartz-garnet-mica-porphyrite in stream above Blea Crag. Slide 3770.
D=Granophyre from Langstrath Beck, south of the Stake Pass. Slide 3787.

A specimen of A taken close to the acid segregation gave 60°51
per cent. of silica; and a dark-green porphyritic rock with pinkisk-
white felspars, intermediate between B and C, yielded 60°49 per
cent. of silica.

A very important feature brought out by these analyses is the low
percentage of magnesia in all of them. ‘The higher percentage of
lime in C (as compared with B) is easily explained, when sections of
the two rocks are examined. ‘The former contains a large amount
of calcite which has, to a great extent, been introduced by infiltration.
In rocks that have undergone such great alteration, it is scarcely
to be expected that chemical analysis will bring out that gradation
which is so well shown in the field. With regard to the alkalies,
the preponderance of potash over soda is hardly to be looked for,
seeing that orthoclase is not found in large crystals in the inter-
mediate rocks. It is doubtless well represented in the groundmass.
The low percentage of alkalies in the dark fine-grained rock A is
remarkable, and may be explained as the result of differentiation.
A section shows concentration of iron-ore. The high percentage of
silica may be due to infiltration.

All these rocks are plentifully veined with quartz and chlorite,
or quartz and epidote. A yellow fine-grained rock is often met

76 MR, E. E. WALKER ON THE GARNET-BEARING [Feb. 1904,

with, cutting through rocks of every kind. A section shows this to
be an epidosite, or aggregate of quartz and epidote-grains. These
veins are found very commonly along slickensided surfaces, and
often give rise to considerable alteration in the adjacent rock, which
becomes lighter in colour, a result due no doubt to the infiltration
of quartz and epidote. It seems fairly certain that water con-
taiming substances in solution and at a high temperature percolated
through these rocks along lines of weakness.

Occasionally the weathered surface of these rocks shows a series
of parallel ‘streaky’ lines: these are seen to be due to the infiltration
of epidote, etc. along minute planes. One specimen which I obtained
showed a slickensided surface roughly parallel to the weathered
surface of the rock; inclined to both occurred a number of fault-
planes, rendered conspicuous by infiltrated epidote. We have in
this hand-specimen a type of structure which illustrates exceed-
ingly well the structure of the whole of the Lake District. The
slickensided surface represents the great thrust-plane, the ‘ streaky’
lines the traces of the lag-faults inclined to the thrust-plane. This
specimen is in Mr. Marr’s possession.

Again, a reticulated pattern of crossing lines producing rhombic
areas may be seen on the rock-face below Bull Crag. ‘The xeno-
liths which occur in the rock have their length along the diagonals.
This structure has been produced by movement along two planes
almost at right angles one to the other.

The dykes of the intrusive mass seen south of Sergeant's Crag
are continued (according to Ward) on the east side of the Greenup
Valley, and extend for some distance over Ullscarf towards
Thirlmere. It is very probable that the dykes mapped in the
neighbourhood of Harrop Tarn are closely associated with the
Blea-Crag rocks. Numerous basic dykes are mapped near the
junction of Angle-Tarn and Allencrags Gills, at the head of
the Langstrath. These bear a very strong resemblance to the more
basic Blea-Crag rocks, and need no further description. Farther
south, a large felsite-dyke is mapped on the Tongue between the
two gills. This comprises rocks varying from a dark-green, basic,
rather fine-grained type, through coarser rocks of a lighter colour,
to a pinkish granophyre, each of which has its representative among
the Blea-Crag rocks.

Il. Inrrvsions 1n THE Bow-Fett District.

Numerous basic dykes are mapped on the ground north of Bow
Fell. One of these runs north-north-west and south-south-east for
some distance, and shows interesting variations of rock. All types
are represented, from a dark-green fine-grained rock, with garnets
and a porphyritic ferromagnesian mineral, to a coarse rock with
garnets and pink-white felspars (5849-3853). The ferromagnesian
mineral is augite in colourless crystals, showing lamellar twinning
parallel to 100. The angle between the twinning-line and the
cleavage varies from 26° to 43°. The felspar is an oligoclase-
andesine with edges obscured by dirty matter, and often replaced by

Vol. 60.] = ROCKS OF THE BORROWDALE VOLCANIC SERIES. 7

chlorite and epidote. Quartz occurs in irregular blebs, frequently
bordered by a ring of minute augite-crystals ; pyrites is often asso-
ciated with the quartz, and encloses the augite-crystals. A striking
feature of the rocks of this dyke is the abundance of oval masses of
infiltrated quartz with a kernel of calcite. On account of this
occurrence, a chemical comparison of the different types would be
futile. In the coarser rocks, oligoclase occurs in long laths in the
groundmass ; the augite is altered to epidote and chlorite.

A large intrusion seen near Buscoe Sike, south of Bow Fell,
shows the same gradation of rocks as the dyke, and no deubt the
two are connected. One of the most basic types (85) is a true
porphyrite with phenocrysts of andesine, or an acid labradorite
showing beautiful zonary banding, Carlsbad and albite-twinning.
Garnet occurs, surrounded by a ring of felspar-crystals of the same
species: iron-ore is separating out from the garnet, and apatite is
also produced. The augite is represented by a greenish product,
plentifully charged with grains of iron-ore. The groundmass is
composed chiefly of plagioclase-laths with iron-ore grains.

Closely connected with the Bow-Fell dyke just described, is a
mass of breccia occupying a considerable area west and north-west
of Ore Gap. It contains fragments from 1 to 2 feet in diameter.
When examined carefully, these fragments are found to be exactly
similar to the varieties of the dyke-rock first mentioned. In addition
to these, fragments of ‘ streaky’ lavas and ashes are also included;
and it is from this breccia that the best example of a ‘streaky’
lava was obtained. Another curious feature of this breccia is the
abundance of quartz-blebs. Under the microscope (3768) lapilli of
an andesitic rock are extremely abundant, the lath-shaped felspars
of which occasionally show a kind of flow-structure. Fragments of
the above mentioned dyke-rocks can be recognized, containing the
ferromagnesian mineral (altered to epidote) and brownish pleochroic
chlorite. Rounded crystals of quartz with their corrosion-borders
preserved are abundant, and these are probably derived from
the north-north-westerly and south-south-easterly dyke. Garnet-
fragments, and portions of the same mineral with well-developed
faces, are not uncommon.

Since the dyke from which the breccia-fragments are presumably
derived is later than the surrounding rock, a question arises as to
the age of the breccia. So far as could be gathered from a hurried
traverse, the breccia-mass has its greatest length in a northerly-
and-southerly direction, parallel to the iron-lode and fault of Ore
Gap: consequently, it would be reasonable to suppose that the breccia
originated through crushing. There are, however, none of the
usual indications of crush-brecciation, and the mass seems to differ
in no way from an ordinary explosion-breccia. Crush-brecciation
would, moreover, hardly account for the fragments of ‘streaky’ lava.

A detailed mapping of the breccia, and a further study of
the behaviour of the few dykes that approach its margin, are
necessary before any theory of a volcanic vent can be brought

78 MR. E. E. WALKER ON THE GARNET-BEARING [ Feb. 1904,

forward. The dykes which run east and west across the Hanging-
Knotts—Bow-Fell watershed bear a marked resemblance, in the
hand-specimens, to those found on the summit of Lingmell. One
variety might be described as being intermediate between an
augite-porphyrite and a granophyre—the augite occurring
in aggregates largely altered to chlorite; uralite is probably an
intermediate product of decomposition. A similar rock runs down
the face of Hanging Knotts to Angle Tarn.

A dyke running north and south along the line of Yeastyrigg
Crags has a central zone of bluish quartz-porphyry, the mar-
gins beiug occupied by a dark-green garnet-rock. ‘This dyke gives
off an east-and-west branch which runs down to Yeastyrigg Gill.
This also is a quartz-porphyry, passing at its edges into a flinty
felsitic rock very hard to distinguish from the surrounding ash.

Passing on to the two small tributaries of the Esk which run
down from Esk Hause, we find, about 200 yards down on the west
side of the eastern tributary, one of the most interesting dykes of
the district. This dyke was not mapped by Ward: it runs almost
due east and west, across the Knotts of the Tongue.

A prominent buttress of coarsely-pitted rock stands out from the
surrounding rock, It varies in thickness from 2 to 3 yards, and
is bordered by a fine-grained, dark-green rock, with a smoother
weathered surface. In the coarse rock are usually to be seen
rounded masses, often | foot or more in diameter, weathering with
a pinkish colour: a fractured surface shows needles of a green
mineral in a pinkish felspar. Similar enclosed fragments also occur
in the fine-grained marginal rock. These included fragments are
composed of hornblende-porphyry (3758). The hornblende
is in the form of long actinolite-needles, giving coffin-shaped basal
sections ; the mineral] is strongly pleochroic. Decomposition yields
chloritic iron-ore, with occasional epidote. The pink-white felspar
shows a pretty microperthitic intergrowth, together with albite-
lamellation and Carlsbad twinning, and is therefore microperthite.
The groundmass is a granophyric intergrowth of quartz and the
same felspar. Apatite is very abundant, in long needles with
characteristic cross-fracture.

The coarse rock (3771) has augite in addition to hornblende ;
the two occurring in about equal proportions. The colourless
augite changes to uralite, the fibres of which show twinning relations
to one another with 100 as twin-plane. An orthoclase may be
present among the turbid felspar, for in one or two crystals the
turbidity is contined to irregular patches, the rest of the crystal
being comparatively clear. Quartz occurs in rounded crystals with
a dirty outgrowth. LEpidote, calcite, and chlorite are abundant.

The fine-grained marginal rock contains augite almost to the
exclusion of hornblende, and plagioclase much altered to white
mica. The rock is a quartz-augite-porphyrite. The concen-
tration of augite in the marginal portions of the dyke is interesting.

This dyke can be traced eastward towards the other tributary

Vol.60.] | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 79

‘of the Esk. The coarse rock dies out, and the rounded inclusions
become more rare until, when the western tributary is reached,
only the fine-grained rock remains, and it shows banding parallel to
the containing walls.

Close to the western tributary and just below the path to Scaw-
fell Pike, a dyke 15 to 20 yards wide occurs: it is of a dark
colour, contrasting strongly with the white of the flinty ash into
which it is intrusive. Fragments of ash and basic xenoliths
weathering light-brown are not uncommon. There are, as usual,
fine-grained and coarse varieties, but all may be classed under the
head of quartz-porphyrites containing pinkish oligoclase-ande-
sine and altered ferromagnesian mineral. One section (3831) shows
a garnet with a margin almost entire and the faces well developed.
On one side corrosion has taken place, and here the felspar-crystals
are grouped round the garnet, together with apatite and a ferro-
magnesian mineral altered to chlorite, and epidote and iron-ore. The
occurrence of the felspar only on that side of the garnet at which
corrosion has taken place, seems to prove that the garnet has con-
tributed some constituent to the formation of the felspar, and not that
the garnet has simply acted as a convenient nucleus for the growth
of felspar-crystals. Ward continued this dyke in a northerly-and-
southerly direction to the junction of the two tributaries, where a
similar rock occurs. ‘T’o connect the two together in a district
where dykes are so numerous, is perhaps somewhat speculative.

III. Bastc OrrsHoots FRoM THE EskpaLe GRANITE.

In the Blea-Crag dykes every type of rock, from a basic porphyrite
to an acid granophyre, was found. I therefore wished to see whether
the Eskdale Granite-dykes yielded the same varieties of rock. Alarge
number of dykes are given off from the granite of Wastdale Head,
and may be well seen on the slopes of Great End and Scawfell Pike
to Lingmell Beck. Dropping down from the Sty-Head watershed,
excellent examples of rock bearing the greatest resemblance to Blea-
Crag rocks may be seen in Spouthead Gill.

Going up the grassy tongue between Piers and Girla Gills, a
very typical dyke is met with 200 feet below Criscliffe Knotts.
The most basic rock is a fine-grained diabase, represented in
places by a greenish rock containing quartz, chlorite, epidote, and
phenocrysts of indeterminable felspar.

The next type is a basic mica-porphyrite, with either
andesine or an acid labradorite, mica, and uralite. The section
(3855) is taken across the junction of the rock with the flinty ash.
Movement has taken place between the two, with the result that
the plagioclases are broken up into small fragments.

The next in order is a coarse purplish rock, with greenish-white
felspar (3856). It is a quartz-porphyrite with altered
andesine, mica-flakes, and rare hornblende-crystals. The felspar
is altered to epidote and white mica. The groundmass consists of

80 MR. E. E. WALKER ON. THE GARNET-BEARING [| Feb. 1904,

felspar-laths, biotite-flakes, iron-ore, and quartz. The felspar and
biotite may sometimes be seen in ophitic relation, giving to the
groundmass the appearance of a quartz-diabase. Aggregates of
uralite occur, in addition to hornblende, and these seem to show
a change into biotite. Biotite-flakes are developed at the margin
of these aggregates, and the pleochroic colours of the mica may be
seen in scattered areas within the mass of uralite-fibres.

The next type (3857) is a similar rock, but the felspars are of
a pinkish colour. Microscopically, it differs only in the fact that
quartz is most abundant, and the groundmass becomes more grano-
phyric in character. Aggregates of mica-flakes occur instead of the
uralite, and this probably indicates complete transformation of
uralite into biotite. There is a good deal of evidence for this change ;
but occasionally the appearance of the section suggests the opposite
conclusion, that is, the conversion of biotite into uralite. Apatite
is abundant in this last type, and is usually concentrated in the
more acid porphyrites. Garnet also is present in rounded crystals.
Corrosion has occurred, with the production of brown mica in
minute flakes (3833); plagioclase-laths are set at right angles to
the surface of the garnet, and give the appearance of a spherulitic
growth round the garnet. Apatite also occurs, and again seems to
be a product of corrosion. Biotite and plagioclase too have been
formed within the garnet.

The most acid rock, and that which occupies the centre cf the dyke,
is a pinkish granophyre. Idiomorphic felspars, either albite
or oligoclase-andesine with albite, Carlsbad, and Baveno-twinning,
occur in a confused intergrowth of quartz and felspar. Rounded
quartz-grains are set in the centre of rudely-spherulitic growths.
Chlorite with strings of epidote developed along the cleavage
represents original mica.

The silica-percentages of these rocks show an interesting

gradation.
Silica-percentages. Specific gravities.

Dia DASE” patsy a: <dptce ose suatl kin odemebake 47°76 2°872 at 15°5° C.

Nica-porphyrlte:.:-:.2.,d:0naeepouee eee 54:04 2°836 at 15°5° C.

Mica-porphyrite (3856)..............2..-+0. 55°75 2°822 at 12°6° C.

Mica-porphyrite with granophyric |
aroundinass (S857 ).5.-ssencseiade. oes 62°38

Granophyte(O8D8)) bes:cs4ecteeep mee cee 68°66 2°753 at 12:1° C,

The broad dykes which traverse Kirkfell, and are well seen in
the gullies of Kirkfell Crags, are quartz-porphyries (3901)
with a beautiful granophyric groundmass. ‘They are of a purplish
colour, due to aggregations of mica-flakes. The felspar is probably
very close to oligoclase. Xenoliths of a basic mica-rock are also
common (3898). A little to the west of Kirkfell summit a red
quartz-porphyry occurs (3899), containing quartz and plagioclase,
with phenocrysts of micropegmatite in a granular groundmass
of quartz and orthoclase. Exactly the same features are exhibited
by the Fence-Wood dyke on the opposite side of the valley.

The larger apophyses of the Wastdale-Head Granite occur in
rounded patches on the summit of Lingmell, at Bursting Knott, and

Vol.60.] ROCKS OF THE BORROWDALE VOLCANIC SERIES. 81

‘on each side of Piers Gill. The Lingmell rock is a good grano-
phyre with crystals of uralite, derivative after augite. Large
plagioclases occur as phenocrysts, in a micropegmatitic intergrowth
of quartz and felspar. Basic xenoliths similar to those of the
Kirkfell rocks are quite common.

The periphery of the Lingmell intrusion is occupied by a purple
porphyrite. Making a good junction with this is a
bluish-grey garnetiferous rock. This, at first, I took to
be the extreme product of metamorphism of the surrounding ash,
but a section (3923) shows the granophyric character of the rock.
Similar grey garnetiferous rocks occur at the margin of the intrusive
rock on the left bank of Piers Gill, and also at the margin of the
Eskdale Granite south of Stony Tarn.

The Piers-Gill rock (3840) consists of quartz and felspar, the quartz
being developed in irregular grains. Pyrites is abundant; the pre-
sence of this mineral—a typical product of contact-metamorphism—
is suggestive. Tourmaline occurs in prisms with strong dichroism,
and giving straight extinction parallel to their length. Garnet in
rounded crystals is present, altered at the margin into white mica.
Quartz-porphyries with tourmaline and garnet occur at the
margin of the Eskdale Granite, undoubtedly intrusive into the
surrounding ash, so the Piers-Gill rock may be of this type.

The main mass of the Eskdale Granite, of which that at Wastdale
Head is a small portion, was next visited. The granite preserves its
characteristic features quite close to its margin. The border itself
is usually occupied by agranophyre- or quartz-porphyry.
From the granite basic dykes are given off. These are exceedingly
numerous, and can be well studied in the neighbourhood of Stony
Tarn. They are easily distinguished by their dark colour, in con-
trast with the purplish tinge of the surrounding rock. The dykes
run east and west, or west-north-west to east-south-east, and can be
followed for considerable distances. One that occurs on the crags
immediately south of Stony Tarn can be traced almost uninter-
ruptedly from the granite-margin to the granite again, over a dis-
tance of half a mile or more. The rocks are typical diabases,
containing long crystals of (3878) labradorite in ophitic relation
with plates of uralite derivative of the augite. Kernels of augite
are still found. Iron-ore in minute graius is also a product of the
change. The uralite moreover undergoes decomposition into a
serpentinous product, which pseudomorphs the plagioclases. Other
varieties do not show any ophitic structure, the uralite occurring in
roughly-idiomorphic crystals (3880).

When these dykes are traced to the granite, no intermediate
rocks between the diabases and the quartz-porphyry are found.
A great number of these basic dykes were mapped by Ward, and
there are probably a greater number still unmapped. They occur
on the Illgill side at the head of Wastwater, north of Slight Side,
on the south-western slope of Lingmell, and in Lingmell Gill.
On Yewbarrow a series of them are mapped, and there are many

a 0.G. S No. 207. @

82 MR. BE. BE. WALKER ON THE GARNET-BEARING [ Feb. 1904,

others besides, all of varying texture. To a large extent they
determine the remarkable gullies on Yewbarrow summit—namely,
Great Door and Little Door.

An excellent example of these uralite-diabases is to be seen
about 80 yards north-north-west of Kirkfell Tarns (3907). Ophitic
structure is well shown, slightly-purple augite occurring in the
centre of the uralite-plates. The uralite-fibres tend to change into
biotite and serpentine at their margins, and minute biotite-flakes
are also developed in the centres of the uralite-plates. This trans-
formation of uralite into biotite has been noticed above in the case of
the Criscliffe-Knotts dyke (p. 80). The fact that the change, how-
ever it may be produced, occurs in a typical diabase lends support
to the conclusion that the intermediate mica-porphyrite
rocks of Criscliffe Knotts have been produced by the
tntermixture of an acid granophyric rock with the
basic diabases. That some sort of intermingling takes place
is evident from the study of the Blea-Crag rocks, but there the
rocks have been much altered and do not often show the original
minerals. Alternative theories will be dealt with below.

This Kirkfell dyke contained a xenolith of what appeared to bea
‘streaky’ rock. <A section (3844) of this xenolith shows a banded
felsite, with abundant mica-flakes grouped in lines. Quartz-grains
surrounded by a spherulitic growth of felspar are found, together
with sheaf-like aggregates of felspar-fibres resembling variolitic
structure. This felsite has its nearest analogue in the banded
felsite of Burtness Combe, Buttermere (see p. 84).

It scems, then, as if all these basic dykes were given off from the
Eskdale Granite. Grey quartz-porphyries are very typical
marginal modifications of the Eskdale Granite. They are seen to be
intrusive into purple ashes and Eycott Lavas south of Brockshaw Gill,
the intrusive rock sending veins into the metamorphosed rock and
producing a pretty mosaic. These vems become darker close to the
metamorphosed rock, a certain amount of absorption taking place.
The intrusive rock (3918) consists of a micropegmatitic growth of
microperthite and quartz. Tourmaline and chlorite are found, the
latter derivative after biotite. The former is but sparingly deve-
loped, usually in irregular crystals with bluish pleochroic colours.
Micreperthite is very common in these rocks, and shows beautiful
intergrowths. Patches of felspar with albite-lamellation are scat-
tered through a large mass of orthoclase. Occasionally the inter-
growth gives an effect very similar to the cross-hatching of microcline.
The orthoclase is usually the more turbid mineral (3879).

Another type of acid intrusive is seen in Slide 3919. It is a
typical quartz-porphyry intrusive in banded ash. As
the result of metamorphism, a light-green fibrous minera! with high
polarization-tints has been developed in the altered ash, and is
especially abundant at the junction. This mineral (which may be a
fibrous hornblende) has been absorbed by the quartz-porphyry,
and occurs throughout the slide.

Vol. 60.) ~ 5 : VOLCANIC S$ : $3
Vol, 60. | ROCKS OF THE BORROWDALE VOLCANIC SERIES. Se

Immediately south of Stony Tarn a darker grey rock forms a
mosaic with, and seems to be intrusive into, the purple-banded ash.
Sections of this rock (3841-3846) show a granular aggregate
of quartz and felspar. Irregular patches of the green fibrous
mineral, together with aggregates of strongly-pleochroic biotite-
flakes, occur. Garnets are abundant: they show the same
characters as the garnets found in the aitered ash, being irregular
in outline and of a very spongy nature, freely penetrated by quartz-
grains. We have, then, in this rock, three minerals found in the
metamorphosed ash; if this rock be intrusive, and there seems no
reason to doubt it, a considerable amount of absorption of the meta-
morphosed ash must have taken place.

It has been noticed above that aggregates of uralite- and mica-
flakes occur in the dyke-rocks of Criscliffe Knotts. That these
minerals also occur as products of metamorphism is rather suggestive.
Absorption certainly dces take place, but it would perhaps be going
too far to ascribe the formation of these intermediate rocks of the
dykes to such a process of absorption by an acid rock. The presence
of the same minerals in the altered rocks and in the dykes renders
it a somewhat difficult task to distinguish between a purple dyke-
rock and an altered Eycott Lava. Above the granite of Oliver Gill
both dyke and altered rock may be seen, and it is almost impossible
in the field to say where the dividing-line comes. Another example is
seen north of Great How, on the extreme edge of the rock-exposure.
Here a black rock occurs, apparently intrusive. Under the micro-
scope large phenocrysts of plagioclase are observed, often very much
broken and corroded, and penetrated by aggregates of biotite-flakes.
Large mica-flakes also occur. Microscopically, the rock resembles
a highly-altered Eycott Lava.

The Eskdale Granite itself rarely contains garnets. In a section
of this rock a small fragment of garnet occurs associated with quartz
and biotite. The quartz nearly envelops the garnet, and a large
biotite-flake has been produced as the result of the action of the
quartz on the garnet. Chlorite occurs as an alteration-product of
the garnet (3927).

LV. Tue Inrrusive Compiex or Burress Compe, BurrerMeRe.

Seeing that the Buttermere Granophyre comes into contact with
the Eskdale Granite at the foot of Wastwater, the basic dykes on
Yewbarrow might be supposed to come from the Buttermere rock.
Accordingly I visited a basic intrusion mapped by Ward on the
western flank of Burtness Combe, Buttermere. It forms a roughty-
oval mass, and a contorted felsite-dyke is mapped as occurring below
it. This may be so, but certainly a contorted felsite-dyke runs from
the south-eastern corner of the intrusion right through it, and is
continued on to the main granophyre-intrusion. This varies from a
light-brown to a greyish, or more rarely pink, rock, and shows good
banded structure. ,

The basic rock through which it passes was described by Ward
as a quartzose diorite. It is, however, a good diabase containing

G3

84 MR, E, 5. WALKER ON THE GARNET-BEARING | Feb. 1904,

long plagioclase-crystals (3889), rather turbid and quite unlike the
clear labradorite that one is accustomed to see. The extinction-
angles correspond rather with an oligoclase-andesine. The ferro-
magnesian mineral is uralite, in greenish fibrous masses which
show twinning with (100) as twin-plane, with strings of limonite
running along the cleavage. Calcite is developed along the margins
of the uralite, and in small patches within the mass. Further
change results in the production of an almost colourless and isotropic
chlorite. Ilmenite occurs in ragged crystals, with a peripheral
growth of brownish sphene. Rods of ilmenite crossing at an angle of
60° are also found. In other sections (3892) augite is present as a
kernel to the uralite, and the ilmenite has good crystal-outlines.

At the junction between the basic rock and the banded felsite
considerable intermixture has taken place, with the production of
an intermediate rock. ‘This intermingling is well shown by the
weathered surface of the rock at the junction, which has rather the
appearance of a breccia. ‘The intermediate rock is a quartz-
diabase (3890). It has the same felspar as 3889, developed in
oblong crystals with Carlsbad and pericline-twinning. The ground-
mass is of quartz and the same felspar—the two occurring in
micropegmatitic intergrowth.

The banded felsite (3893) shows spherulitic growths of felspar-
fibres, either alone or with quartz. Chlorite-flakes representing
original mica occur, and these separate off iron in the form of ferric
oxide. Muscovite-flakes are diffused throughout the slide. This
felsite is undoubtedly connected with a beautifully-spherulitic rock,
which occurs just above the wall only a few yards from the Combe
Beck. The spherulites have a core of reddish earthy matter, which
is seen under the microscope to be the product of the decomposition
of the chlorite-flakes that occur either as a central aggregate or in
rings. The felsite was probably first intruded, and the diabase
came up later.

To show that intermediate rocks have been produced at the
junction, I made silica-percentages of these rocks; but unfortunately,
owing to a mistake in the numbering of the slides returned to me,
I tested only the extreme types :—

Silica-percentages. Specific gravities.

Diahbase (S880) oy cy teveteseeue 50°12 2°830 at 18°3° C.
Diabase (G892) tcc. eee s meaee 49-52 2°831 at 16°8° C.
Banded felsite (8893) ......... 72°46 2683 at 20°3° C.
Banded felsite cassvits.tseee T2221 ——__—__—.

These diabases resemble very strongly the diabases of Stony Tarn
(3880: see p. 81). It will be seen that, both macroscopically and
microscopically, it will prove difficult, if not impossible, to say
definitely whether a given dyke belongs to the Eskdale or to the
Buttermere intrusion. From what I have seen of the two rocks, |
have come to the conclusion that, if not of the same age, they
have been produced from the same rock-magma. Both show rocks
of intermediate character containing garnets; in the case of the

Vol. 60.] ROCKS OF THE BORROWDALE VOLCANIC SERIES. 85

Buttermere rock I have not seen these garnet-bearing rocks 7m situ,
but the numerous loose blocks in Burtness-Combe Gill afford
sufficient testimony to their occurrence.

V. Orner GARNETIFEROUS INTRUSIONS IN THE LAKE District.

Acid garnet-bearing dykes occur in ali parts of the district. The
dyke mapped at Fox Tarn on Scawfell is a good quartz-
porphyry containing quartz, microperthite, plagioclase, chlorite
after biotite, garnet, and apatite. The garnets are surrounded by
quartz, but they are broken up and replaced by chlorite and epidote.
The occurrence of this latter mineral points toa fair percentage of lime
in the garnet. A very similar rock occurs low down in the stream
and on the western flank of Rosthwaite Combe, and roughly at the
same horizon in asmall patch on Rosthwaite Fell. This is a greenish
rock, with pink-white felspars and garnet. The latter mineral
has usually one or two faces well developed, but is elsewhere
embayed by quartz. |

More basic garnetiferous rocks occur at Dock Tarn, Harrop Tarn,
and along the Wythburn valley. Many of the rocks mapped as
Javas by Ward in Wythburn and on Helvellyn are in all probability
intrusive. The Dock-Tarn rock is found east-north-east of Stone-
thwaite Church, and runs from the valley to the top of the Great
Crag; the path to the top of the hill follows its outcrop very closely.
It may also occur on the lower slopes of Rosthwaite Fell. It was
mapped as a lava, but Mr. Marr proved its intrusive nature from
the metamorphism of the surrounding ash. It is a minor sill,
intrusive into garnet-breccia and banded ash. The upper limit is
well defined by the altered ash, but the lower limit is hard to make
out, for it is somewhat difficult to distinguish between cleaved
intrusive rock and the garnet-breccias. It may be described as a
sill of garnetiferous andesite, with phenocrysts of
plagioclase. The rock is in parts intensely cleaved, the felspars
become broken up, and the garnets are altered to chlorite and white
mica with separation of iron-ore. Flakes of chlorite and sericite are
developed throughout the rock. The percentage of silica is 58°08.

Similar rocks are found at the base of the Eycott Lavas, imme-
diately south of the stream issuing from Dock Tarn, where the
same kind of metamorphism occurs ; and also in the triangle formed
by the roads at the western end of the Thirlmere dam. Here the
metamorphosed ash only becomes white and porcellanized close to
the junction, no new minerals being developed.

A quarter of a mile north-west of Harrop Tarn, Ward mapped a
massive lava: this Mr. Marr considered to be intrusive. The
microscopical characters of the rock bear out this supposition.
It isa quartz-garnet porphyrite, with highly-altered plagio-
clase. Quartz occurs in rounded and corroded crystals, surrounded
by a zone of lighter groundmass. Pseudomorphs of chlorite, epidote,
and calcite after an original ferromagnesian mineral, apatite, and

86 MR. E. EH, WALKER ON THE GARNET-BEARING [ Feb. 1904,
pyrites are plentiful. The rock in parts is highly vesicular—quartz,
calcite, and chlorite filling the vesicles. The junction of the rock
with banded ash may be seen in the streams flowing into Harrop
Tarn, but the metamorphism is hardly appreciable.

The quartz-porphyrites of Helvellyn and Wythburn are of the
same type. The silica-percentage of a quartz-porphyrite between
Greenburn and Wythburn is given by Mr. W. M. Hutchings as
60°45, with a specific gravity of 2°74.

The Armboth Dyke also contains garnets. A slide (3788:
Pl. XIII, fig. 3) through one of these garnets shows beautiful
corrosion by quartz-crystals. The quartz has penetrated along
definite planes, and has left projecting needles of garnet. It is
very probable that the Armboth Dyke is closely related to the basic
dykes near it. By a mistake in the wording of the Geological-
Survey Memoir, an analysis of the St. John’s quartz-felsite is
ascribed to the Armboth Dyke. Mr. Harker’ has shown that the
analysis does not belong here, and the numbers tabulated below
support this view :—

Per cent.

SiO see kee 75°26
AN Once Meche roltne nee 12°85
Hel O UN Nes mven ce eee es Only
| OL OS al See Bae sin Coo 1°36
Mini@) Six sore ua caee (22
Cait Son gins ihn Eee Sens 0:83
Me OSE Mi paved saute (0:04
Oa tart ut eaten 501
IN GUS Ooi oat sccienst tre au 2°66
OCR NE GES, nee 0:04
EL) te Sas cheng oie Onna ae 1:04
Loss on ignition ......... (1:29)

99°48

Specific gravity =2°648 at 16:4° C.

Vi. Garnetrrerovus Rocks 1n tHE Fatcon-Crag ANDESITE-GROUP.

Having dealt with the intrusive garnet-bearing rocks of the
district, it would be well to take the members of the Volcanic
Series in order. The lower part of the group consists of :—

Banded Ashes and Brececias ;

‘Streaky “ Rocks ;

Kycott Lavas, and associated ashes and breecias;
Falcon-Crag Lavas and Ashes,

The Falcon-Crag Group consists of andesitic lavas and
ashes, typically developed round Falcon Crag on the east side
of Derwentwater. Ward described them in detail, and the only
rocks with which we need deal are those that contain garnets.
The lowest of these is Ward’s ‘No. 2 ash,’ well seen at the
base of the small scarp beneath Falcon Crag. The ash is overlain
by ‘No. 2 lava, and is of no great thickness. Garnets are

* “Chemical Notes on Lake-District Rocks’ in the ‘ Naturalist’ for 1899, p. 150.

Vol. 60.] ROCKS OF THE BORROWDALE VOLCANIC SERIES. 87

sometimes very numerous; but they are usually of small size, and
present a very fragmentary appearance in hand-specimens of the
rock.

A section of this rock (3753: Pl. XIII, fig. 4) shows numerous
fragments of andesitic lava, with small felspars and much ragged
iron-ore. There may be one or two fragments of sedimentary
rock derived from the Skiddaw-Slate Series. The garnets are
obviously fragmentary, and are not found in the lapilli, but in the
andesitic groundmass. They sometimes have a spongy character.
Felspar-crystals are occasionally seen clinging to the margin of the
garnet. As the result of infiltration, greenish and almost isotropic
chlorite is found, together with needles of calcite, throughout the
slide. The iron-ore enclosed by the chlorite is extensively converted
into brown pleochroic sphene, Quartz occurs in oval fragments.
An analysis gave a silica-percentage of 54:34.

Garnets probably occur in the higher members of the series.
This mineral was found in a coarse ash close to ‘lava No. 6’ on
Brown Knotts. Again, immediately to the south of Barrow-Beck
Waterfall, a bright-green ash with garnets occurs at the base of
the prominent scarp. The thick garnetiferous lava ‘ No. 10’ occurs
above it, and can be traced almost continuously from Barrow to
High Seat.

This lava varies greatly in appearance—sometimes forming a
greyish-green rock with many felspars, and not unlike the intrusive
rock at Dock Tarn; at other times it is of a very dark green, and
the felspars are less numerous. A section of the latter type shows
phenocrysts of plagioclase, with Carlsbad and albite-twinning and
good zonary banding (3755), in a very fine andesitic groundmass,
Flakes of biotite highly charged with magnetite occur, and these
undergo change into chlorite, calcite, and iron-ore. ‘he iron-ore
(ilmenite) gives rise to sphene peripherally. Garnet occurs abun-
dantly (3782, 3829), and often shows the ring of felspar, with
detached fragments cf garnet lying in the centre of the plagioclase-
erystal. The centre of the garnet is also frequently corroded, and
occupied by felspar. Iron-ore is always separated. In other cases,
the garnet simply undergoes a peripheral change to chlorite. Ward
mentioned the occurrence of augite. Apatite is often seen. The
rock is a typical andesite, and has a silica-percentage of 61°38. '

Ward mentioned a higher lava ‘ No. 12, as containing garnets,
and he gave an analysis of it, the percentage of silica being 59°511.°

Garnet-bearing ashes and breccias are very abundant on the hill-
side behind the hotels at Rosthwaite. Highly-cleaved garnetiferous
breccia occurs in Frith Wood, and an alternating series of garnet-
lavas and breccias extends from Brund Fell southward to Dock
Tarn, On Brund Fell itself a fine-grained greenish ash with good
banding is seen; this is the common greenish ash of the district.

‘ Harker, ‘Chemical Notes on Lake-District Rocks’ in the ‘ Naturalist ’ for
1899, p. 57.
* Quart, Journ. Geol. Soc. vol. xxxi (1875) p. 408.

88 MR. E, E. WALKER ON THE GARNET-BEARING [ Feb. 1904,

Numerous small garnets may be observed in the ash, but unless
specially looked for they would escape notice.

The Frith-Wood breccia is intensely cleaved, and the garnets
show an interesting transformation. They are seen to consist of
a collection of irregular fragments, surrounded by a colourless
substance of indefinite outline. Between the fragments flakes of
what appears to be a colourless mica are developed ; chlorite-filakes
are also present, and possibly quartz is set free along with rods
and irregular masses of ilmenite or other iron-ore.

This peculiar change takes place in all cleaved garnet-bearing
rocks: the garnet-fragments become smaller and finally disappear,
leaving only a few grains of iron-ore and an indefinite sericite-lhke
growth. Examples of this change are afforded by the cleaved
intrusive rock of Dock Tarn previously described (p. 85), by a
cleaved lava on the lower slopes of Rosthwaite Fell, and by the
garnet-rock of Cockley Beck in the Wrynose Valley.

The cleaved garnet-lava of Rosthwaite. Fell (3766)
shows the change very well. The garnet-fragments lose their
isotropic character at the margin, and yield high polarization-tints
between crossed nicols. The refractive index, however, remains the
same. There seems to be no intermediate stage between this and
the production of the colourless mineral, which has a refractive
index lower than that of the chlorite. Cleavage-lines are often well
shown, but the flakes do not always give straight extinction, the
angle of extinction being sometimes as great as 15° or 18°. The
mineral is exceedingly like a colourless mica, but might be either talc
or kaolin. Ifthe mineral be a white mica, it seems almost impossible
to discuss the change chemically. The greater part of the iron of
the garnet is eliminated and the iron-ore set free, while the chlorite
would account for the rest of the iron, the magnesium, and possibly
the calcium; but it is difficult to account for the alkali necessary
for the production of the colourless mica. There would be no great
difficulty in accounting for the production of either tale or kaolin.

Garnetiferous lava and breccia are well developed on the small
plateau around Dock Tarn. A lava of considerable thickness over-
lies the intrusive sill, and has a silica-percentage of 64:2.' The
same rock occurs on the other side of the valley on the lower slopes
of Rosthwaite Fell. Above it is found the garnet-breccia of Papelay
Crag. A sill of considerable thickness is intrusive into this breccia,
producing similar metamorphism to that of the Dock-Tarn intrusive
rock, Intrusive junctions are to be seen in a field south-east of
Stonethwaite Village, where some friend of the geologist had done
some extensive blasting, and also on the east side of the valley close
to asmall peat-bog. Ward mapped this rock as a lava, and, to explain
the intrusive junction last mentioned, brought in a thin basic dyke
from an intrusive mass occurring close to the Watendlath path. This
intrusive sill is closely connected with the intrusions round the old

* Harker, ‘Chemical Notes on Lake-District Rocks’ in the ‘ Naturalist’ for
1899, p. 57.

Vol.60.] | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 89

‘Borrowdale graphite-mine, and resembles in texture an intrusive
rock in Sourmilk-Gill Combe. It is not a garnet-bearing rock. It
probably extends some distance eastward, for a very similar rock is
met with at the same horizon on Watendlath Fell.

Garnet-bearing ashes and lavas are extensively developed on the
high ground between Borrowdale and Thirlmere, but very little
attention has been given to them. The garnet-lavas on the Dock-
Tarn plateau greatly resemble the garnet-lava No. 10 of the Falcon-
Crag Series (p. 87); and it is quite possible that in them we have
the uppermost members of that series.

The next great group of the Eycott Lavas and associated
ashes occurs immediately to the south of them, and forms prominent
escarpments on both sides of the valley. Garnets do not occur in
these lavas, except in the neighbourhood of intrusive masses such
as the Carrock-Fell rocks, where they are doubtless the product of
contact-metamorphism.

VII. Tap ‘Srrraxy’ Rocks oF THE Cenrrat Movntary-Districr,
We have next to deal with the group of ‘streaky ’ rocks. A good
idea of the mutual relations of these rocks may be gathered from
the appended diagrammatic section through Rosthwaite Fell. .

Fig. 2.— Diagrammatic section through Rosthwaite Fell,

N,

Stonethwaite
Church

gb=garnet-breccia. b/=ash and breccia.
gl=garnet-laya. e=Eycott Lavas.
s=intrusive sill. st =‘ streaky ’ rocks.

gp =garnet-quartz-porphyry.

The term ‘streaky’ has been applied tu these rocks from the
characteristic appearance of the weathered surfaces. These show
either a series of parallel wavy lines, or a multitude of lenticular
inclusions with the same orientation. Strictly speaking, rocks
showing this ‘ streaky ’ character occur in all parts of the district
and at all geological horizons, but a well-developed band of them
is generally found above the Eycott Lavas.

This type of structure might arise in various ways.

(1) By infiltration of substances along definite planes. This is
frequently noticed, not only in the typical ‘streaky’ rocks, but in
rocks of all geological horizons. The infiltrated substances belong
to the following :—quartz, calcite, chlorite, epidote, and ilmenite.
These are often introduced along the bedding-planes, and the
parallel streaky lines may be separated by considerable intervais.
Good examples are afforded by certain lava-like rocks on Gosforth

90 MR. B. KE. WALKER ON THE GARNET-BEARING | Feb. 1904,

Crag and the lower slope of Bell Rib, Yewbarrow, also in the
intrusive sill just mentioned as occurring in Rosthwaite Fell.
In the last rock the lines are often separated by several inches.
Quartz, calcite, chlorite, and ilmenite are found, the two first
occupying the centre of the vein. The rock in close proximity to
the vein takes on a speckled and dirty appearance, due to the
dissemination of minute chlorite-flakes. Again, fault-planes are
a determining factor, An example of this kind has already been
instanced in the case of the Blea-Crag rocks, where epidote and
chlorite have been introduced along what might be termed ‘ planes
of lag-faulting.’ In the ‘ streaky’ rocks proper infiltration has taken
place most frequently along the bedding-planes ; but veins produced
along fault-planes do occur, crossing the bedding-planes at all angles.

Very often the infiltrated products assume a lenticular shape.
This is well shown by the greenish rocks of Whelter Crag (Hawes-
water). Dark-green lenticular patches are developed in a lght-
green rock, with felspar-phenocrysts. These dark-green patches
consist of chlorite and calcite, sometimes accompanied by quartz ;
a discoloration in the rock-matrix surrounding these patches is due
to the dissemination of minute chlorite-flakes (3802). The rock
presents the character of a rhyolitic ash, and the infiltrations
may be very similar in origin to that of quartz in rhyolites.

More rarely, infiltrated chlorite occurs in the same way as in-
trusive veins, penetrating a rock and enclosing fragments broken off.
These fragments have chlorite introduced along the bedding-planes
or other planes of weakness, and a ‘streaky’ character is thereby
given to them. A good example of such action is afforded by
loose block found on the slope of Mickle Moss in the Hawes-
water district, and these phenomena may be seen in Slide 3817.
The rock is a pinkish-white rhyolite, showing phenocrysts of
orthoclase in a felsitic groundmass, with irregular felspar-patches.
The chlorite occurs irregularly , elther in long patches or in minute
veins cutting across the felspars, and o¢ casionally replacing them by
chlorite-pseudomorphs. Another example of a mass of chlorite
behaving as an intrusive rock is afforded by banded ash, near the
junction of the streams from Bleawater and Smallwater Tarns in
the Haweswater district.

We might expect to find a similar ‘ streaky ° character :

(2) As the result of lamination in fine fragmental rocks ;

(3) As the result of flow of igneous material;

(4) As the result of dynamic action on included fragments.

It may be stated at once that all four types of structure can
be found, and that it would be impossible to ascribe all ‘ streaky ”
structures to one origin. At the same time, it is a very difficult
matter to say definitely to which class a particular ‘streaky’ rock
belongs.

With regard to the distribution of ‘streaky’ rocks, they are
generally found in a zone between the Eycott Lavas and the typical

Vol.60.] | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 91

Banded Ashes. Speaking roughly, they form a ring round the
highest part of the district, A very typical section of the whole
group may be seen on Base Brown, which is entirely composed of
them. ‘They run obliquely across Sourmilk-Gill Combe and form
the big masses of Great Gable and Green Gable. Lingmell and the
stretch of rock from Slight Side to Greencove Wyke on Scawfell
are entirely composed of them. They are lost to sight beneath
Eskdale Moss, but appear again on Gait Crags and form the rugged
and lofty ground stretching from Buscoe Tarns southward to Crinkle
Crags and beyond. ‘They probably occupy a considerable area
south of Oxendale, and may extend to the Wrynose Valley. They
fill the Langdale Valley to a height of 1000 feet, and run round to
Kasedale Tarn. Farther I have not traced them.

From Base Brown they may be followed eastward across the
Derwent Valley to Hind Side and the lower slopes of Glaramara.
They form the rugged plateau of Rosthwaite Fell, and run obliquely
across the lower ends of the Langstrath and Greenup valleys, and
occur on the top and slopes of Cold-Barrow Fell above Blea Tarn.
Farther east they are absent, and are probably cut off by the north-
west to south-east fault mapped by Ward.

In addition to this regular outcrop, they occur in patches in
many districts. They form a great part of Yewbarrow, and at
Stirrup Crag is an excellent development of them. They also occur
on Illgill Head (Wastwater), and on the lower slopes of Helvellyn
in the neighbourhood of Whelpside Gill, where a yellow ‘streaky ’
rock is overlain by a blue flinty ash.

Although well developed and of great thickness in the central
part of the district, they do not occur between the Eycott Lavas
and the slate-band in the south. Their absence in this tract of
country led Mr. Marr to put them on the same footing as many
of the other garnet-bearing rocks of the district, and to suggest
that they were intrusive into the Volcanic Series. At first sight
there appears to be a good deal of evidence in favour of such an
intrusive theory, despite the obviously-fragmental nature of some
of the rocks.

At their upper junction with the Scawfell Banded Ashes there is
almost universally a great intermingling of the two rock-types.
The banded ash seems to have been absorbed in great quantity, so
as to form a complex mosaic of highly-altered, greenish-white, flinty
ash and garnet-rock. This is exceedingly well shown on a rock-face,
a few yards south of Buscoe Tarns on Bowfell. A good example
also occurs immediately south of the gate at the Langstrath Gorge,
Where a white flinty ash with greenish streaks is caught up by a
reddish garnetiferous rock. It is through this complex that the
stream has cut so deep a gorge.

Many intrusive rocks show this phenomenon. On a minor scale
the garnet-bearing intrusive rock at Great Crag, Dock Tarn (fig. 3,
p. 92), 18 seen to incorporate the banded ash and form a mosaic.
But an excellent example is afforded by the Eskdale Granite just
south of Stony Tarn, where the stream from the tarn enters a small

‘(UMD T 90 ) bpwg IDIOM 1D YIOL ALISNAZWA snowafyautpb PUD YSY papuvg —'S ‘oly

Vol.60.| | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 93

-Yavine. A similar mosaic occurs in Sourmilk Gill, opposite Sea-
thwaite Farm, where the rocks round the graphite-lode are intrusive
into banded ash.

It would be impossible to conclude from the sections at Buscoe
Tarns and on Aaron Crags, Seathwaite Fell, that the garnet-rock
is intrusive. The appearances would be better explained on the
supposition that the flinty ash was the intrusive rock. This
intermingling at the junction between the two rocks has been
caused by intense pressure. The bedding-plane between the
soft Banded Ashes and the harder garnet-bearing rocks has
very probably been one of lag-faulting; the pressure has been
so great that the ash has been altered and incorporated with the
garnet-rock.

An excellent section about 1500 feet up, almost due west of the
Langstrath Gorge, illustrates this action. To the north the streaks
are seen to dip southward, at an angle varying between 20° and 30°.
As the junction with the banded ash is approached, the ‘ streaky’
lines become horizontal. They develop into whorls, and small thrust-
planes can be distinctly seen. Fragments of ash become incorporated
close to the junction. If the garnet-rocks were intrusive, we should
expect to find some evidence of intrusion at the lower junction. Here
a complex is by no means common, and where it is absent no meta-
morphism has taken place.

A perfectly-gradual passage from ash to ‘streaky’ rock is seen
on the crags west of Galleny Force, Stonethwaite. Elsewhere on
Rosthwaite Fell disturbance has takeu place, and we have altered
flinty ash running in thin veins at right angles to the bedding. It
would appear that the pressure was so great that the ash was
either partly melted, or became sufficiently plastic to be forced into
the surrounding rock.

The junction on the south-eastern slope of Sourmilk-Gill Combe
affords evidence of great pressure. The rock at the junction
is of a dark green, with bands of lighter green representing
the incorporated ash. This rock is so much hardened that the
softer ash has weathered away from beneath it, thus leaving a
ledge of rock which projects 2 or 3 feet from the hillside.

This evidence of the operation of pressure in the production of
these friction-breccias, combined with the obviously-fragmental
nature of the rocks, serves to dispose of the intrusive theory. The
reason of the non-occurrence of the ‘streaky’ rocks in the south has
yet to be explained.

Many of these ‘streaky’ rocks contain derived fragments, and
these may be lenticular or of irregular shape. A glance at the
weathered surface would, in many cases, convey the idea that the
rocks were fragmental; in others, that they were lavas showing
flow-structure. Included fragments in lavas, especially in the
rhyolites, are quite common. ‘The intrusive rocks of the district
are, moreover, full of xenoliths, so that there seems to be no
insuperable difficulty in accepting the third explanation of the
‘streaky ’ character.

94 MR. KE. E. WALKER ON THE GARNEI-BEARING | Feb.-1904,

We are face to face with the old difficulty of distinguishing
between a rhyolite and a rhyolite-tuff, for these ‘streaky’ rocks
show many points of resemblance to those acid rocks. Ward
mapped all these rocks as ashes, but at the same time he pointed
out that so thick a mass of rock would be sure to contain small
lava-flows which it would be almost impossible to trace in the
field.

If the garnets of these rocks are examined, it is found that they
are not always perfect in form, but are often surrounded by
a white ring which, under the microscope, is seen to consist
of plagioclase-crystals growing out from the garnet-margin in
good crystal-forms. The garnet is always very much corroded ;
the projecting portions are often curved, and lose their isotropic
character at the extremities, Fragments of garnet occur in the
feilspars (3819), showing the same polarization-tints as the felspar,
and only differing in refractive index,

A compact green rock from Kagle Crag in the Langstrath valley
(3824) shows the association of felspar and garnet exceedingly well.
Very little garnet remains, but the fragments are surrounded by eight
or ten idiomorphic plagioclase-crystals of the same species as that
which occurs in the rest of the rock. Lron-ore, probably ilmenite,
has separated out in rods and irregular masses, and has been largely
converted into a brownish sphene. Flakes of chlorite also occur.
The streaks are formed by lines of felsite-material: these, as they
approach a large felspar in the neighbourhood of the garnet, seem
to become discontinuous and exhibit folding and crumpling. This
suggests that the felspar was formed after the streaks of felsitic
material. ‘The formation of ferromagnesian mineral, as a result of
the corrosion of garnet, is rarely seen in the ‘ streaky’ rocks, but
is fairly common in the garnet-intrusives.

Garnets, with perfectly-developed faces, occur in an ash at the
base of the ‘streaky’ rock on Rosthwaite Fell. In section (3836)
the garnet is seen to be breaking up at the margin, felspar being
produced. The original outline of the garnet can, however, be traced.

A study of the garnet-intrusives has led us to believe that the
association of felspar and garnet affords evidence for
the originality of the garnet, the felspar having been pro-
duced by the action of the still hquid matter cn the garnet. Garnets
surrounded by felspar-growths also occur in undoubted ashes and
breccias, above the series of ‘ streaky’ rocks (3834 & 3845). It
would seem, then, that this association affords no criterion for
discrimination between a lava andam ash; and the fact that it occurs
in true ashes throws doubt on the interpretation put upon it 1m the
case of the intrusive rocks. In the examples of ‘streaky’ rocks
mentioned above certain features seem to point to the formation of
the felspar after the consolidation and compacting of the rock.

It might be urged that the garnets with a felspar-ring which
occur in the ashes are fragmental. A glance at the felspar-crystals
is sufficient to convince one that this is not the case: for they often
show very perfect crystal-outlines, with sharp and deep re-entrant

Vol. 60.| = ROCKS OF THE BORROWDALE VOLCANIC SERIES. 95

-angles between contiguous telspars. This would hardly occur if
the garnet and the felspar-growth were thrown out together.

Before proceeding further, it may be well to describe a few typical]
examples of ‘streaky’ rocks. The lowest rock of the series exposed
on Rosthwaite Fell is a light-green rock with pinkish-white felspar
in abundance. ‘This is seen in section (3780: Pl. XIV, fig. 1) to
be a plagioclase, much altered to calcite. Fragments of a grano-
phyric rock occur, showing a pretty micrographic intergrowth and
needles of chlorite representing original biotite. These granophyre-
fragments resemble very closely the Buttermere Granophyre. We
have, then, another piece of evidence, besides the occurrence of
garnet, which serves to show how closely connected the rocks of the
Volcanic Series are with the garnet-bearing rocks intrusive in them.
In addition, fragments of an andesitic groundmass, with diffused
iron-ore, are also present. The matrix is felspathic, and minute
felspar-fragments occur with concave outlines. The rock may thus be
called atuff-porphyroid. Garnets with exquisitely-bright faces
are common, Purplish flinty fragments as well as dark chloritic
basic portions occur; it is the squeezing of the latter that gives
the ‘ streaky’ character to the rock.

Other types are found, in which the ‘streaky’ character is
due to thiu lines of green chloritic matter (3772). Phenocrysts of
plagioclase occur at all inclinations to these lines, which are often
bent as if the felspar had fallen on them from above. ‘This chloritic
matter is original, and not produced by infiltration. Running across
the streaky lines are others, formed also of chlorite or more rarely
of chlorite and quartz. These are true veins, infiltration having
occurred along lines of faulting, for the vein may be seen to pro-
duce displacement of the fragments of a felspar through which it
may pass.

At other times, the streaks are broader, and consist of a coarse
felspathic matrix impregnated with quartz, chlorite, and calcite
(3870). Aggregates of calcite are very characteristic of this class
of rock, as well as skeleton-crystals of ilmenite enclosing a green
or greenish-brown, pleochroic, serpentinous mineral. ‘This occurs in
the ‘ streaky ° rocks of Borrowdale and Haweswater alike.

Another type of ‘streaky’ character consists of lenticular fragments
of quite different petrological and chemical composition. Such a rock
is shown in the microphotograph (3875: Pl. XLV, fig. 2) and occurs
at Hindside, Seathwaite. A similar rock-is to be found on the lower
slopes of Scawfell. Yellowish-white lenticular patches of rhyolite
occur, separated by a darker and more basic fine-grained matrix.
These rhyolitic aggregates contain felspars, probably oligoclase or
oligoclase-andesine, in the usual felsitic paste. The felspars are,
however, not peculiar to the rhyolite-fragments, but occur through-
out. Tufts and wisps of an almost colourless mineral occur, giving
bright polarization-tints. ‘his mineral is associated closely with
chlorite, and seems to pass into it. ‘The same mineral, which I am
unable to identify, occurs abundantly in the Haweswater rocks.

96 MR. E. E. WALKER ON THE GARNET-BEARING {| Feb. 1904,

This mixture of a rhyolitic with an andesitic matrix explains the
peculiar chemical composition of these ‘streaky’ rocks. They have
silica-percentages varying from 63 to 69, which are much lewer
than those of true rhyolites. The percentages of lime and mag-
nesia are also low, but are intermediate between the percentages of
these constituents in andesites and rhyolites. Potash preponderates
over soda, although the difference is not by any means so great as
in the typical rhyolites.

The two following partial analyses were made :—

A. B.
Per cent. Per cent.

SIOpL Parnes, 68°89 66-92
MO, )
Tiber Peewee 19-69 20°50
Fe,0, |
CAO) 82 x eat at sey a9 1-69
I ees 0:20 0-22
HG) 4, Ne ee 2-61 3:56
NaRin0. 26h pitch atenes 2°42 277
Specific gravity...... 2'679 at 18°C, = 2°704 at 12°79 C.

A= Lowest ‘ streaky’ rock, west of Galleny Force.
B=‘ Streaky ’ rock, 1750-foot contour, Whelter Crags.

Ward gives the analyses of two rocks, one from Base Brown!
and the other from Slight Side; the former has a silica-percentage
of 69°673, the latter 68°421.

Mr. Harker* tabulates the silica-percentage of an lgill-Head
‘streaky’ rock as 69°48, and its specific gravity as 2°682.

The specific gravities of ‘ streaky’ rocks from Scawfell (38876) and
Base Brown were found to be 2°706 and 2-694 respectively. An
excellent example of a rock in which the andesitic and rhyolitic types
occur together, is afforded by a thin band of ‘streaky’ rock found
below the main mass of ‘ streaky’ on Gait Crags. In it are lenticles
of colourless rhyolitic substance and brownish andesitic ash, the
latter containing many broken fragments of a labradorite-felspar.
A less convincing example occurs at the base of the High-Goat-Gill
series in the Haweswater District. —

So far, I have described ashes in which the ‘streaky’ character is
due to a large extent to lamination, but may also be produced by
pressure and by infiltration of various substances. ‘That there are
also minor lava-flows in so great a thickness of rock seems pro-
bable. Ward pointed out the difficulty that would be experienced
in tracing such thin lavas. He did, however, map the compact
columnar rock on Base Brown as a lava. IJ have no slide of this
rock, and have never come across a rock im situ that I could call
a lava.

A loose block found by Mr. Marr on the path to Sty-Head Tarn
from Seathwaite shows a lava-like character. It is a typical
‘streaky’ rock, with dark-brown streaks and enclosed fragments of
' Quart. Journ. Geol. Soc. vol. xxxi (1875) p. 411.

* Chemical Notes on Lake-District Rocks’ in the ‘ Naturalist’ for 1899, p. 56.

Vol.60.] | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 97

flinty ‘streaky’ rock. In section (3786: Pl. XIV, fig. 3) it shows
oblong orthoclase-crystals always oriented in the direction of the
‘streaky * lines. There are bands of light and dark matrix, the
former containing fibres of a brownish mineral which gives straight
extinction parallel to the length of the fibres. Aggregates of quartz-
grains in oval patches, possibly representing original vesicles, contain
the same fibrous mineral. The rock is frequently faulted.

The second example of a ‘streaky’ lava is furnished by the rock
obtained from the garnet-breccia of Ore Gap. Slightly turbid pink-
white felspar, giving the extinction-angle of oligoclase, occurs in
rounded and corroded crystals, thinning out in the direction of flow.
Fine-grained andesitic fragments have been caught up and rounded.
The groundmass is that of a true rhyolite, exhibiting the
characteristic appearance of light and dark patches. Along certain
lines the structure becomes coarse and lenticular, and linear aggre-
gates are seen, consisting of idiomorphic felspars in quartz. Cubes
of pyrites of a reddish tinge are common, especially in the more basic
streaks ; they usually possess a dark interior, and are surrounded
by a ring of epidote. Ilmenite and apatite occur.

There are undoubted lavas in the Haweswater District. One of
these, a typical rhyolite with a silica-percentage of 82:25, is
mentioned by Mr. Harker’ as occurring a quarter of a mile
south-east of Walla Crag. A garnetiferous andesite occurs
at the top of the series at Woot Crag, on the Naddle side of Hawes-
water. This yielded a silica-percentage of 59-70, and Mr. Harker
tabulates its specific gravity as 2-698.

Above the ‘streaky ’ rocks comes a great thickness of banded
ash and breccia, filling up the syncline in the highest part of
the district. A zone of crush-brecciation has been mentioned
as occurring at the junction over wide areas. ‘his plane of crushing
does not, however, keep to the same horizon. It can be traced
from the eastern shore of Sty-Head Tarn, over the watershed and
down to Lingmell Beck. n the slopes of Lingmell ‘streaky’ rock is
developed both above and below the line of crush-brecciation. The
phenomena rather suggest a reduplication of ‘ streaky” rocks by
thrusting.

‘Streaky’ rocks are developed on [lgill Head; between them and
the Lingmell rocks occurs a band of andesite and Eycott Lavas.
The Illgill-Head rocks have not been carefully mapped; but this
intercalation of Eycott Lavas between two bands of ‘streaky’
rock is particularly suggestive, when the succession in the Hawes-
water area isconsidered. ‘These patches of ‘streaky’ rock developed
on Ilgill Head and at Stirrup Crag (Yewbarrow), may, however,
occur only in faulted areas, for the ‘streaky’ rocks elsewhere form
a complete series.

The rocks immediately above the ‘streaky’ rocks consist of a
greenish ash and breccia containing fragments of ‘streaky’

* «Chemical Notes on Lake-District Rocks’ in the ‘ Naturalist’ for 1899, p. 57

Q.J.G.8. No. 237. H

98 MR. E. E. WALKER ON THE GARNET-BEARING | Feb. 1904,

material. They are typically developed north of Glaramara, and
are good andesitic ashes. They contain garnet-fragments, but
these are not common; there can be no doubt about the clastic
nature of the garnets.

The breccia found at Lining Crag (Greenup Gill) is a typical
rock (3754) consisting of lava-fragments with oval vesicles ;
fragments of a rhyolite with perlitic structure, the cracks
being filled with greenish chlorite. Garnet and felspar-fragments
occur. Perlitic rhyolites are occasionally met with in fragments
in many rocks. A good example (3926) occurs as an enclosed
mass in Dock-Tarn Gill.

Above these greenish ashes and breccias comes a more com-
pact series of ashes, which may assume a more or less
pronounced ‘streaky’ character. These are well seen on Allen
Crags, and south of the Angle-Tarn to Esk-Hause path: they
often contain perfect garnets. In a rock from Allen Crags (3871)
the ‘streaky’ character is produced by lenticular patches of
chlorite squeezed out by pressure. Fragments of andesitic and
rhyolitic rocks occur abundantly, together with infiltrations of
chlorite. Felspar-fragments are also abundant. Garnets sur-
rounded by a felspar-ring are often found in these rocks; ashes
from Esk Hause, near the path to Scawfell Pike, and on Scawfell
Pike itself, show this association well (3834 & 3845). A better
example is afforded by the compact, blue, flinty ash above the
‘streaky’ rock in Whelpside Gill, Helvellyn (8839: Pl. XIV,
fig. 4).

A very fine, exceedinely-compact, flinty ash, with oval concretions,
is found in the centre of the syncline. Garnets are not often to be
seen in this rock, on account of its fineness; but a mass of ash and
breccia included in it on the Knotts of the Tongue (Esk Hause)
contained garnet-fragments. Minute garnets have been found by
Mr. W. M. Hutchings in the equivalent rocks of the slate-band in
the south, so that all the lower members of the Volcanic
Series, with the exception of the Eycott Group of
lavas and ashes, contain garnets.

VIII. Tue ‘Srrraky’ Rocks oF tHE HAweswatTer Disrricr.

Garnetiferous rocks are well developed around Haweswater.
They present all the characteristic features of the ‘ streaky’ rocks
in the centre of the Lake District, but differ considerably in their
mode of distribution. J have endeavoured on the 6-inch maps to
plot them out roughly, and to this end a peculiar nodular rock—as
pointed out on p. 18 of the Geological-Survey Memoir, on ‘ The
Geology of the Country between Appleby, Ullswater, & Hawes-
water’ 1897-—-forms a valuable guide. The rocks are developed in
bands, separated by lavas and ashes which do not contain garnets.
Now, the ‘ streaky ’ rocks in the centre of the district, with perhaps
one exception, occur in one great group: the object of the mapping
was to determine whether this structure was original or produced ©
by earth-movements.

Vol.60.] ROCKS OF THE BORROWDALE VOLCANIC SERIES. 99

‘Streaky ’ rocks are met with at Measand Forces, at the top of
which banded ash is seen dipping eastward. Below the ‘streaky ’
group a coarse rock occurs, which has the appearance of an Eycott
Lava. The line of junction between the two is vertical, and much
crushing has occurred at the junction. Between the two rocks on
Sand-Hill Knotts a fine-grained, dark, basic rock occurs, and several
dykes of the same traverse the ‘ streaky’ rocks, though not the rock
below.

The ‘streaky ’ rocks run in a north-westerly direction to Colby,
frequently displaced by faults. They are developed on Great and
Little Birkhouse Hills; a dark intrusive rock occurs below them.
Intrusive junctions may be seen, in which the ‘streaky’ rock becomes
reddish in colour and of a flinty character. The intrusive rock
is a quartz-diabase (3805). It seems very probable that the
Measand rock is also intrusive, and the two, with the diabase of
Walla Crag (on the other side of the lake), form a large intrusive
mass.

Below the ‘streaky’ rock of Little Birkhouse Hill occurs a narrow
band of vesicular lava, separating it from the nodular rock
on Pinnacle Howe. This rock consists of oval nodules of fiinty
material, the centre of which is either hollow or filled with quartz.
These nodules vary from half an inch to 6 inches in length. The
same rock is again seen at the Old Quarry north of Fordingdale
Bottom, and thence it probably extends along the hillside to
Fordingdale Force, where an excellent section is exposed. It is
continued along the top cf the slope to Laythwaite Crags, and on
-round Whelter Combe in a vertical cliff about 100 feet high. The
succession here is—

Feet.
Compact garnetiferous rock................:0:0.s0e00e 20
CO aes be IPR A SS Or eee 10 to 15
Garnetiferous rock with vesicles............ .....-.. 50 to 60

The nodular rock varies in thickness, and has a very irregular
top and base. On Whelter Crags it splits into two, and is then lost
by faulting. Occurring again in the upper part of Randale Beck,
it runs to Kidsty Pike, where it is well developed in two bands.
This rock is not represented on the east side of Haweswater. On
p. 17, ete. of the Survey Memoir (quoted on p. 98) the rock is
described as ‘bomboidal,’ and considered to be of fragmental origin.
This is quite likely, for similar flinty fragments (with quartz de-
veloped in the centre of them) may be found in a compact ash
on Eagle Crag and Rosthwaite Fell, in the Borrowdale district.
Together with the quartz in the hollows, a black substance also
occurs, either forming a coat on the quartz-crystals or in oval grains.

Above the great cliff of garnet-rocks in Whelter Combe, lavas
possibly of the Eycott type, vesicular lavas, and ashes are developed ;
and these are succeeded by a yellow, much-decomposed ‘streaky ’
rock at the top of Bason Crags.

Below the nodular rock-group, banded ash is seen, dipping
north-westward at an angle of 5°. Another band of garnet-rock is
found crossing the stream just above High-Whelter Farm—being

H 2

100 MR. E. E, WALKER ON THE GARNET-BEARING [ Feb. 1904,

continued northward towards Laythwaite Sike, and southward to
Castle Crag and on to Randale Beck.

Between Whelter Knotts and Laythwaite Sike an interesting
group of rocks occurs. The ground is much faulted, diabase-
dykes coming in along the faults. All along the road near the
School and Rowan Park a yellow rhyolitic ash with
pyrites is developed. An analysis of a specimen from Rowan
Park yielded a silica-percentage of 72°18.

In Laythwaite Sike a very dark-brown rock occurs, either alone,
or in lenticular fragments in a yellow matrix: this gave a silica-
percentage of 31:77. Microscopical examination shows the rock to
be made up almost wholly of chlorite, and the low silica-percentage
obtained supports this conclusion. Along the 1500-feet contour
from Laythwaite Sike to Whelter Knotts this mixed yellow-and-
black rock becomes converted into a schist with white quartz and
a greenish mineral. Weathering of the rock produces a wonderful
mosaic, the quartz standing out from the red iron-oxide produced
by the decay of the green constituent. This mineral, under the
microscope (3806), is seen to occur in irregular yellowish patches,
giving high polarization-tints. It is derived from chlorite, for
a section (3812) shows the passage of one into the other. At
the margins of these patches, and scattered throughout the matrix
of quartz-grains, occur minute irregular prisms of a greenish,
strongly-pleochroic mineral, giving high polarization-tints and ex:
tinction oblique to the length of the prisms. Wisps and tufts of
the same mineral have been noticed very frequently in association
with chlorite in the ‘ streaky" rocks elsewhere. It must be closely
allied to chlorite in composition. A compact quartz-schist has
been produced by dynamic metamorphism from the yellow and
brownish aggregate. The silica-percentage is intermediate between
the two given above, for it is found to be 64°77.

On the east side of Haweswater ‘streaky’ rocks are well developed,
They occur in the north between High-Laithes Pike and Walla Crag,
being continued from Pinnacle Howe on the opposite shore. Cleaved
Eycott Lavas form a thin band near the base of the series. They
run in a narrow belt, frequently interrupted by diabase-intrusions,
to the head of Naddle Beck, and then spread out over the heather-
covered ground as far as Woof Crag and Powley’s Hill, descending
to the lake along the line of Guerness Gill. Patches of intrusive
quartz-porphyry are often found, and a considerable mass of the same
rock is found in them on Mardale Banks, south-east of the end of
the delta.

At Woof Crag a garnetiferous andesite (already mentioned
on p. 97) occurs, overlain by banded ash. Along the junction
movement has taken place, with the resuit that the lava shows
excellent crush-conglomerates. Basic dykes break through it
frequently. Diabase-dykes of a dark-green colour and of fine
grain are common on the west side of the lake, occurring south of
Birk’s Crag and above the Schools. Quartz-porphyry dykes
are also found on Whelter Knotts.

The intercalation of laya and ashes which do not contain garnets

Vol. 60.] | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 101]

‘in the ‘streaky’ rocks seems to be an original feature. A study,
both microscopical and chemical, of these lavas is necessary, before
it can be asserted that the Eycott Group is associated with the
‘streaky’ rocks in one area and that itis older than them in another.

IX. Tue CHARACTERS OF THE GARNETS.

These are of no very great interest from the crystallographic point
of view. In the intrusive rocks and the majority of the ‘streaky ’
rocks they do not usually show good faces. The well-developed
garnets are found in abundance in the ashes of I]lgill Head, High-
Goat Gill (Haweswater), and Sty-Head Tarn.

The only two forms met with are the icositetrahedron (211)
and the dodecahedron (110). The icositetrahedron is occasion-
ally found singly, but I have never met with the dodecahedron
alone. The majority of the garnets show a combination of the two
forms, the relative size of the respective faces varying considerably.
Garnets a quarter of an inch in diameter are quite common, but
the extreme limit is half an inch.

The occurrence of a ring of felspar round the garnet, with the
production of ferromagnesian mineral and separation of iron-ore,
has already been considered (pp. 73, 94). The conversion of the
garnet into a sericitic substance by dynamic metamorphism has also
been noticed (p. 88). _

The garnets found in the greenish rock of High-Goat Gill, a
tributary of Naddle Beck (Haweswater), show somewhat peculiar
features. This rock is an andesitic ash, containing many felspar-
erystals in a greenish matrix charged with chlorite. The silica-
percentage is 56°45. The garnets are extremely abundant and
almost perfect in outline, but usually show a small indentation
occupied by the greenish matrix. ‘This cavity may occur anywhere
on the crystal, and has no relation to the crystallographic axes.
it may be either five- or six-sided, according to the number of
faces which it cuts, but it is often roughly circular in outline.
A series of step-like projections running round the cavity occur all
the way down to the bottom, and seem to represent the layers of
garnet-growth. This phenomenon is singularly suggestive of a
metamorphic origin for the garnets. The rock is an undoubted
ash, therefore the cavities could not be formed by corrosion. There
may be two such cavities in one garnet, and nearly all the garnets
show the same phenomenon. It is extremely improbable that such
hollows would be found in fragmental garnets. If the garnets are
metamorphic, it is difficult to understand how such metamorphism
has been produced, for the rock is far removed from an intrusion
of any great magnitude.

Chemically, the garnets are iron-alumina garnets, with small
quantities of calcium, magnesium, titanium, and manganese-oxides,
and therefore belong to the almandine-type. This was proved
by qualitative analysis, and by quantitative estimation made on
those garnets which could be procured in some quantity with
little trouble: these are to be found only in the ashes at the
upper and lower limits of the ‘streaky’ rocks. To obtain

102 MR, E, E, WALKER ON THE GARNET-BEARING | Feb. 1904,

sufficient amounts of the mineral from the intrusive rocks for
analysis it would be necessary, in the majority of cases, to have
recourse to separation by heavy liquids. The garnets analysed
were obtained from the garnet-ash of High-Goat Gill, the ‘streaky’
ash of the prominent crag west of Galleny Force, and the ashes
of Illgill Head and Sty-Head Tarn. Titanium is present in all
four, and only a small percentage of the iron is in the ferric state.
It is not unlikely that water may occur in these garnets, but no
estimations were made.

The most frequent change that the garnets undergo is a con-
version to greenish chlorite with separation of iron-ore. Generally,
the change proceeds irregularly from the outside to the centre.
In a ‘streaky’ rock from Lady’s Seat (Mardale), the garnets give
rise to flakes of chlorite in a direction at right angles to that of the
cleavage in the rock. Under great pressure the garnets lose their
reddish colour, become a dirty brown, and pass gradually into an
aggregate of chlorite and a sericitic mineral.

I wish here to express my thanks to Mr. Charles Smith, formerly
at the Mineralogical Museum, Cambridge, for all the help which he
gave in the preparation of rock-sections containing special garnets.

X. Meramorpuism of THE Votcanic Rocks.

The metamorphism of volcanic rocks by a granitic intrusion has
been thoroughly dealt with by Messrs. Harker & Marr’ in their
papers on the Shap Granite and associated metamorphic rocks, and
by Mr. Harker * in his paper on the Carrock-Fell Gabbro.

‘The metamorphosed rocks round the Eskdale Granite show very
much the same characters. The rocks in which new minerals are
developed are either ashes or Eycott Lavas. These become choco-
late-brown in colour, owing to the development of aggregates of flakes
of an intensely-pleochroic brown mica, probably produced from
chlorite. Close to the intrusive junction a very pale-green mineral
is developed, forming either irregular masses or elongated prisms
giving high polarization-tints. This mineral, as before mentioned,
becomes absorbed into the intrusive rock. The mineral may be a
fibrous hornblende.

The extreme type of metamorphism is furnished by xenoliths of
purple ash, enclosed in the intrusive quartz-porphyry. Examples
occur west of Stony Tarn (3887) and at Piers Gill. Numerous
brown mica-flakes occur in a holocrystalline mass of quartz and
plagioclase. The two last-named minerals are hard to distinguish
one from the other, both being perfectly clear.

Garnets with very irregular outline are also produced, the border
being of a very spongy character freely penetrated by quartz and
plagioclase. The process of formation of these garnets appears to
be most interesting. At first, there is a confused mass consisting

* Quart. Journ. Geol. Soe. vol. xlvii (1891) pp. 292-809 & vol. xlix (1893)
pp. 360-65.
* Ibid. vol. 1 (1894) pp. 331-34.

Vol. 60. | ROCKS OF THE BORROWDALE VOLCANIC SERIES. 103

ot chlorite-flakes, a minute granular aggregate, and comparatively-
large pieces of a brownish isotropic mineral with occasional tri-
angular outline. This has rather the appearance of sphene, but
the mineral is isotropic: it may be one of the spinels—picotite,
perhaps. In the next stage we find a highly-refracting mineral with
peculiar blue and bluish-green polarization-tints, massed round the
grains of spinel. This mineral has a higher refractive index than
the spinel, and seems to bea garnet of non-isotropic character.
The brownish spinel loses its colour, and changes into an opaque
iron-ore. This becomes gradually absorbed, and a true isotropic
garnet is produced.

The non-isotropic garnet might very well be grossularia,
for the polarization-tints are characteristic of that mineral, and
there is no difficulty in this assumption when the large amount
of plagioclase present is considered. It is a curious fact that the
larger masses of garnet show no trace of the spinellid mineral, but
at their outer edges pass into the non-isotropic garnet. That some
such change as this does occur seems fairly certain, but it is very
desirable to obtain confirmation by chemical methods.

The fiakes of biotite in this rock show numerous pleochroic halos,
and apatite seems to occur as a product of econtact-metamorphism.

The production of garnets in the ash is limited to fragments
caught up and enclosed by the intrusive rock. The purple ash does
not usually contain them. It appears therefore somewhat absurd
to ascribe the perfect garnets of lgill Head and Sty-Head Tarn
to the same metamorphic action.

Lavas, possibly of the Eycoti type, come close to the garnets just
north of Stony Tarn, and also at Brockshaw (ill. The product is a
purplish rock, with greenish-white felspar-substance. Under the
microscope aggregates of mica- flakes are seen to be very common, set
in a mass of plagioclase. Nearer the junction north of Brockshaw
Gill the purple colour is lost, and we get a grey rock with occasional
garnets (3930). This rock is not found further than 2 feet above
the line of junction, and passes into the purplish rock above.

A metamorphosed Eycott Lava in Oliver Gill shows the production
of brown mica and a light greenish hornblende.

A purplish ‘ streaky ’-like rock south-east of the head of Wast-
water exhibits minute biotite-flakes, aggregated round ragged patches
of iron-ore (3793). Biotite is often observed in association with
a greenish hornblende. Aggregates of quartz-grains are frequently
associated with biotite in these rocks, but there is nothing to show
that such aggregates are the result of metamorphism.

Coming to the examples of contact-metamorphism by a small
intrusive mass, we find these in the ash above the intrusive
garnet-bearing rock of the path to Dock Tarn, and in a similar ash
at the upper limit of the intrusive sill on Rosthwaite Fell. The
phenomena are the same in both, consisting of a production of
black crystals and flakes of chlorite. In the Rosthwaite-Fell
metamorphosed rock (3778) irregular flakes of greenish chlorite are

104 MR. E., E. WALKER ON THE GARNET-BEARING [ Feb. 1904,

developed, enclosing portions of the groundmass. Calcite occurs
in small grains and patches, often resembling felspar in outline and
possibly replacing that mineral. Ragged ilmenite-aggregates occur,
extensively altered to sphene. In the Dock-Tarn rock the chlorite
shows well-developed faces. Close to the junction this mineral is
not developed, the ash becoming white and porcellanized, and the
metamorphic minerals pyrites, chlorite, etc., are found at some
distance from the junction-line. These spotted ashes are probably
closely allied to the ‘ spilosites.’

The same minerals occur in a very compact flinty ash enclosed
in garnetiferous rock, at the junction of the ‘streaky’ rocks
and Banded Ashes at the Langstrath Gorge. The ash is whitish,
with greenish streaks and patches. These patches consist of chloritic
aggregates, with irregular masses of calcite (3765). That the
pressure at the junction was intense is proved by the occurrence
of these minerals in whorls, the minute chlorite-flakes forming
concentric rings, It is quite probable that the heat produced by
the intense pressure has been the cause of the production of new
minerals.

It has been mentioned elsewhere that a considerable thickness of
fine flinty ash occurs in the highest parts of the district ; it would
seem that the flinty character has been produced by the joint
agency of heat and pressure. A small fault occurs in garnet-
bearing rocks near Black Hall in the Wrynose Valley. Fragments
of ash have been dragged along this line, and a flinty rock produced.
In other cases, the compact flinty character is due entirely to
contact-metamorphism. Round the intrusive Blea-Crag rocks
occurs on both sides of the Langstrath an aureole of flinty ash
and breccia, and to a great extent this compact flinty character
is produced by heat derived from the intrusive rock.

EXPLANATION OF PLATES XIII & XIV.

Puate AIT.
Fig. 1. Slide 3751: corroded garnet, surrounded by a plagioclase-ring, with
biotite in the embayments. Magnified 12 diameters. (See p. 73.)

2. Slide 3787: garnet and orthoclase, surrounded by a microspherulitic
growth of quartz and felspar. In parallel arrangement with this
growth elongated flakes of chlorite are seen. Magnified 16 diameters.
(See p. 74.)

od. Slide 5788: from the Armboth Dyke, showing corrosion of garnet by
quartz. Magnified 16 diameters. (See p. 86.)

4. Slide 8753: ash from the Falcon-Crag Group. Magnified 16 diameters.
(See p. 87.)

Puate XIV.

Fig. 1. Slide 5780: ‘streaky’ rock from Rosthwaite Fell, containing fragments
of granophyre. Magnified 14 diameters. (See p. 98.)

. Slide 8875: ‘streaky’ rock from Hindside (Seathwaite), showing pale
patches of rhyolite separated by a darker and more basic matrix.
Magnified 14 diameters. (See p. 95.)

. Slide 38786: ‘streaky’ rock from a loose block on the path between
Sty-Head Tarn and Seathwaite. Magnified 8 diameters. (See p. 97.)

4. Slide 3839: blue flinty ash, above the ‘streaky’ rock, Whelpside Gill

(Helvellyn). Magnified 12 diameters. (See p. 98.)

ht

(ot)

Quart.Journ.Geol.Soc.Vol.LX,PI1. XIII.

4. X16

Mintern Bros.imp.

F.H Michael del.et li

ROCKS FROM THE BORROWDALE

VOLCANIC SERIES.

Quart.Journ.Geol. Soc Vol.LX,P1.XIV.

1. X14

4. 412

Mantern Bros.imp.

FH.Michael del.et lith,

ROCKS FROM THE BORROWDALE

VOLCANIC SERIES.

Vol. 60.] | ROCKs OF THE BORROWDALE VOLCANIC SERIES. 105

Discussion.

Mr. Harker said that to listen to this paper made one regret
more keenly that the Author had not been spared to continue the
work so well begun. The remarkable relations described in the
paper between intimately-associated basic and acid intrusions had
escaped his (the speaker’s) notice when working with Mr. Marr in
the Lake District ; but they found a parallel, even in some of the
minor details, among the Tertiary intrusions of the Inner Hebrides.

The origin of the garnets, so striking a feature of the Lake-
District rocks as a whole, was an important question, upon which
the Author’s researches would undoubtedly throw light. The
uneven distribution of the mineral pointed toa metamorphic origin,
and the detailed nature of the distribution was such as to connect
the garnets with metamorphism of the dynamic kind.

Prof. Sortas said that he joined in the previous speaker's
expression of regret at the premature loss to science of so gifted an
observer as the Author. Much subjectivity attached to the various
interpretations of the mixtures of igneous rocks. In reality
different explanations could account for similar phenomena, and the
supposed simultaneous fluidity of basic and acid rocks was by no
means indispensable to explain the facts. Further, the igneous
magmas were already differentiated before they were erupted at the
surtace of the earth.

Mr. Barrow remarked that Mr. Maynard Hutchings (who was
unfortunately not present) had worked at these very Lake-District
rocks some time ago. Mr. Hutchings had no doubts as to the meta-
morphic origin of the garnets in the ashes, although he did not
feel sure that he could account for it.

106 - MR. AND MRS. REID ON A PROBABLE [Feb. 1904,

8. On a PROBABLE PaLmotiraic Froor at PRaw Sanps (CoRNWALL).
By Crement Rem, Esq., F.R.S., F.LS., F.G.S., and Eneanor
M. Rerp, B.Sc. (Read January 6th, 1904.)

Asour 7 miles east of Penzance a shallow bay les between a rocky
headland of slate and elvan on the one side, and the Godolphin
granite on the other. Into this bay sand, principally shell-sand,
has drifted, so as to show at low tide a mile or so of sandy fore-
shore, behind which occur low cliffs and sand-dunes. This tract
is known as Prah Sands. In its leading characteristics it is a
typical Cornish bay, dating from the period of the raised beach, but
subsequently rendered less important, and partly obliterated, by
changes of sea-level and the accumulation of drift.

The drift in the low cliff at Prah was described in 1879 by
Mr. W. A. E. Ussher’; but nothing exceptional seems to have been
visible at that date, nor was anything unusual observed during two
visits made by one of us in 1901. The ordinary succession of
angular ‘head,’ on raised beach, resting upon a wave-worn rocky
platform, was all that was noticed.

During the severe gales of 1902 and 1903 the sea washed away
much of the talus and sand which masked the foot of the cliff
between Sydney Cove and Hoe Point, and also removed so much of
ihe beach as to lay bare numerous patches of the rocky floor below.
The sections thus exposed are of such great interest as to justify a
detailed description, for they yield what we believe to be the first
evidence of Paleolithic man yet found in Cornwall.

The section lies between Sydney Cove (where the road comes
down to the beach) and the well-known ‘ Prah Elvan,’ less than
300 yards away, and close to the western horn of the bay. The
general relation of the deposits will be readily understood from the
accompanying section (fig. 1, p. 108).

An uneven, wave-worn, rocky platform rises to about 15 feet
wbove high-water on the south-western side of the elvan. Beyond
and behind it is a much-degraded ancient sea-cliff, with traces
of caves, now well above the reach of the sea. ‘This buried cliff
trends inland, and then strikes eastward at a distance of about
200 yards from the present coast. On the rocky platform and
banked against the cliff rest patches of shingly beach (mainly of
elvan and killas), with big boulders and much sand, the whole
deposit seldom reaching 10 feet in thickness; the beach-material
has been entirely decalcified, and is now cemented by iron into a
solid mass. About 60 feet of angular rubble or ‘head,’ loamy at
the bottom and full of large blocks of elvan throughout, at this
point rests upon the raised beach, forming the modern sea-cliff.

On the east side of the elvan-dyke the rocky platform gradually

' ‘The Post-Tertiary Geology of Cornwall’ 1879, 8vo, Hertford (privately
printed) pp. 18, 19.

Vol. 60.] PALHOLITHIC FLOOR AT PRAH SANDS. 107

_sinks to mean-tide level on the foreshcre; and at 70 yards from
the elvan it is lost under recent beach, or has sunk beneath the
sea: it has also a slight seaward tilt. Bedded ferruginous sand,
with well-worn pebbles and Jarge rounded boulders, can be seen at
various points to rest upon this rocky platform and to rise to about
high-water mark ; these deposits, however, do not directly concern
us, and need not here be more fully. described.

The strata to which we wish particularly to draw attention are
those now visible at the foot of the cliff, where they rest upon the
ancient marine deposits, and are clearly seen to pass under a great
thickness of rubble-drift or ‘head.’ Perhaps the clearest way to
show their relation is to give detailed measurements at a point
where the cliff is nearly vertical and free from talus, and where
the recent beach opposite has been swept away, so as to lay bare
part of the foreshore. Such a section was measured at about 150

yards east of the elyan :—
Thickness in feet.
3

‘Head’ or coarse angular rubble of local rocks (elvan, slate, | 99
ARR IIE MEPEERALGID Po cies. ny ange besae oe sbdesicacee avs eicewkes == 5

Loamy ‘ head,’ mainly consisting of vein-quartz ............... 12
Black loam, with fragments of charcoal, burnt bone, and } iv
burnt earth ....... Bee i 2.8. Wa aie ccna as dd ote denne oe c
Grey sandy loam, with small stones and traces of roots] ,
JS ia oe Ee OE Oak ae eee j
EN ge ae ne Se 1
esr recess PER GCN HEME o..., 052 open nas nce as~one~ voces soenens 03

At this point the rocky platform could not be reached, the lowest
bed seen only lying a foot or two below high-water mark.

It will be noticed that in the section just described, the marine
beds are succeeded by a few feet of sandy loam or brickearth. This
loam is traceable for about 200 yards, and is seen wherever the foot
of the cliff is free from talus. In part it may be only worked-up
material formed from the marine strata below; but, in the main, it
seems to be an ordinary soil washed from the slopes above, for it is
full of small chips of vein-quartz, though larger stones are un-
common. Towards the ancient buried cliff which formerly bounded
the old bay on the west, the loam becomes more stony and like the
‘head’ above; but unfortunately that part of the section was some-
what obscured by landslips, and we could not ascertain exactly
where the change occurs.

Careful examination shows that the loam was at one time a true
land-surface, for it is full of small vertical roots. Untortunately,
these are preserved only as ochreous casts, too much decayed for
miroscopic examination. Towards the top of the loam occurs a black
seam, usually about 6 inches thick. At first this was thought to be
peaty ; but on washing a quantity of the material, we could find no
trace of seeds or other fossils. We found, however, that the black
colour was due to abundance of small fragments of charcoal, mixed
with small splinters of carbonized ‘bone, and fragments of burnt

SYDNEY
COVE

(See p. 106.)

fa

EE

[Scales :—Horizontal: 180 feet=1 inch; Vertical: 80 feet=1 inch. ]

Fig. 1.—NSection of the cliff at the western end of Prah Sands.

S)

Slate.

1
k

Elvan-dyke,

R=

Raised beach.

B=

Loam.

L=

Angular ‘ head,’

V8 le

earth. On further
examination, we as-
certained that this
charcoal was par-
ticularly abundant
at several spots
where the loam, as
a rule nearly clean,
contained groups of
three or four blocks
or flattish slabs of
stone, which were
generally of elvan.
At these spots the
black Joam was com-
monly full of pieces
of quartz, usually
small, possibly the
remains of larger
blocks shattered by
fire.

As we had evi-
dently found a true
land - surface, on
which man _ had
made hearths and
lighted fires, a care-
ful search was made
in this black layer.
Unfortunately, the
deposit seems to
have been tho-
roughly decalcified
and the fossils de-
stroyed by perco-
lating water, for only
carbonized remains
are preserved. We
found, however, that
some of the larger
pieces of vein-quartz
in this layer were
apparently fashioned
into rude imple-
ments’; but these
had been battered
into shape, © not
flaked. This ab-
sence of flaking
seems, however, to

* The specimens mentioned in this paper have been deposited at the

British Museum, Bloomsbury, W.C.

Vol. 60.] PROBABLE PALEHOLITHIC FLOOR AT PRAH SANDS. 109

be due to the intractable nature of the only material available.
Vein-quartz breaks with a rough, splintery, fracture, for each
lump is usually made up of portions of many crystals, and the
material will not flake like Chalk-flint or like large crystals of
quartz. No other local material is suitable for flaking into im-
plements, for Chalk-flints are rare here and seldom occur in big
pieces, while the granite, elvan, and slates are unworkable. The
greenstone found in the neighbourhood is an extremely-tough rock,
difficult to trim: but, though it is so suitable for hammer-stones,
we found only one or two small pieces of it in the black seam.
These, like the slate, were much decayed, and apparently had not
been used,

Fig. 2.— Rude implement (?) made of vein-quartz. (See p. 110.)
4

{Photographed natural size. ]

The quantity of charcoal observed, and the number of hearths
found (six or seven) were surprising ; but this bay must have been
a particularly-favourable locality for occupation. It faces south,
is sheltered by high land, and behind the terrace of raised beach the
old sea-cliff in all probability furnished many dry caves suitable for
dwellings. Within a few yards was also a stream of fresh water,

Above the black seam just described come several feet of loamy
drift, in which the stones consist almost entirely of vein-quartz.
Such a material is at the present day the ordinary soil of the

110 MR. AND MRS. REID ON A PROBABLE [ Feb. 1904,

country, where time has allowed of the decay of all other rocks.
Under present climatic conditions similar material is being washed
down the slopes, to accumulate in the flat-bottomed valleys, such
as this must have been. This quartzose base of the ‘ head’ also
yielded a few doubtful implements, one of which is shown in
fig. 2 (p. 109).

The quartzose loam passes upward into the well-known ‘head’ or
rubble-drift of Cornwall, which consists of an obscurely stratified
mass of local rocks, in blocks of all sizes, included in a more or
less loamy matrix. This deposit is so porous that any fossils have
disappeared, if such existed, and we are still without direct evidence
as to the climatic conditions under which it was formed ; but the
evidence seems decidedly in favour of the generally accepted view,
that it belongs to the later stages of the Glacial Period. Its mode
of occurrence strongly suggests soil-cap movement, or movement
aided by snow-slopes or masses of half-melted snow. The blocks
which it contains are fresher, larger, and have travelled farther
down gentle slopes, than is possible under present-day conditions.
It differs from the modern rainwash and soil, and from that below in
which the supposed implements are found ; but these land-surfaces
so closely resemble one another, that it is not easy to distinguish
them where landslips have brought the two into juxtaposition.

Though paleontological evidence is still deficient in Cornwall,
yet the succession in these Pleistocene deposits corresponds so
exactly with that found along the Sussex coast, that we cannot
refrain from thinking that the strata are of the same date. The
‘head’ of the Cornish coast seems to be equivalent to the ‘ Coombe-
Rock’ of the Sussex coast. The raised beaches of the two dis-
tricts correspond. In each case we seem to find between them
Paleolithic and old alluvial deposits.

Discussion.

Mr. E. T. Nrwron explained that, among the North American
implements which he exhibited in illustration of Mr. & Mrs. Reid’s
paper, some beautifully formed arrow-heads were made from an
easily-worked material; but one was made from vein-quartz, a
very intractable substance, from which only very rough implements
could be produced.

Sir Jonn Evans congratulated the Authors on having diseovered
what was very possibly a Pleistocene land-surface in Cornwall, but
he objected to the use of the term ‘ Paleolithic floor.” The word
‘ Paleeolithic’ had a definite significance, and he could not accept
the implements exhibited from Prah Sands as Paleolithic. They
were naturally-formed fragments of vein-quartz, which might indeed
have been utilized by the people whose remains were found asso-
ciated with the hearthstones. The question was only confused by
terming them Paleolithic: there was no evidence to determine

Vol. 60. ] PALHOLITHIC FLOOR AT PRAH SANDS, 111

absolutely the age of the land-surface. All that could be said was
that it was the oldest, of human times, yet known in Cornwall.

Mr. Srrawan considered that the paper was of wide interest.
The raised beach which is recognizable at intervals for many miles
along the coast of South Wales had been shown by Mr. Tiddeman
to be overlain by the Glacial deposits of the neighbourhood. That
it was of earlier date than those deposits admitted of no dispute,
but Mr. Tiddeman had further expressed an opinion that a part of
the raised-beach series was continued into the caves, and was there
associated with the cave bone-beds. He (the speaker), while
believing this to be highly probable, thought that it had not been
actually demonstrated.

This Welsh beach corresponded, without much doubt, to that which
occurred at Weston-super-Mare and at intervals along the coast of
Devon and Cornwall. It seemed, therefore, to be highly probable
that, although no Glacial deposits had been recognized in Cornwall,
the band described by the Authors corresponded in position and
age to beds which in South Wales were overlain by such deposits,
and were probably associated with Pleistocene mammalia.

Doubt had been thrown upon the implements. But it seemed to
him that the facts that stones of a special character had apparently
been assembled for the definite purpose of making hearths, and
that they were associated with charcoal, possessed the greatest
significance. It would be necessary to prove, however, that the
black fragments were really burnt wood, and not vegetable remains
carbonized through lying in a porous matrix,

Mr. A. M. Bett congratulated the Authors on their having found
an inhabited surface of Quaternary time; such were found more
commonly on the Continent than in Britain, as, for example, in
Moravia, on the central water-parting of Europe. The speaker had
once, at a depth of 32 feet in unaltered river-gravel, found carbonized
remains in Oxfordshire, but was unable to find implements along
with them. Of the quartz-implements shown, he considered that
some of them were probably used as tools, and resembled rude
implements of Quaternary time.

Mr. W. Sone said that there could be little doubt that the raised
beaches of the South of England were post-Glacial, as compared
with the Glacial Drift north of the Thames. The late Sir Joseph
Prestwich had already pointed this out * :—

‘ There is the absence also in the Raised Beaches of such northern shells as
Astarte borealis, Leda pernula, Fususislandicus, Natica grenlandica, and others
common in the Glacial drifts. The Raised-Beach mollusca agree therefore
pretty closely with the molluscan fauna now living in the British seas, and

this accords with the stratigraphical evidence, which leads us to place the
Beaches with the latest of the River-valley Deposits.’

The speaker’s own observations confirmed Prestwich’s conclusions.
Mr. G, Crincu enquired whether the Authors could furnish such

particulars as to the number and position of the hearths as might

throw some light upon the approximate length of time during which

' Quart. Journ, Geol. Soe. vol. xlviii (1892) pp. 301-302.

112 PROBABLE PALMOLITHIC FLOOR AT PRAH SANDS. [ Feb. 1904.

this spot was inhabited. He thought that it would be interesting
to know something more as to the character of the hearths and the
exact position of the so-called ‘implements ’ in relation to them.

Mr. P. F. Kenpatt observed that the relation of the raised beaches
to the ¢‘ head’ was clearly shown ; the question turned on the mode
of origin of the latter. He referred to the ‘head’ at Porthleven,
which (as Searles- Wood, Jr., had suggested) was probably the result
of soil-ereep. The pulpy condition ensuing on the break-up of a
severe frost might well produce such a ‘creep.’ It was very sugges-
tive that the materials of which the hearths consisted were derived
from elvans.

Mr. O, A. Surussorr asked for further evidence as to the age of
the carbonaceous layer. ‘The fragments of vein-quartz were not in
themselves sufficiently definite.

Mr. Rep, in reply to Mr. Strahan, explained that charcoal is
almost indestructible, and the crumbs found in the loam have the
rectangular fracture characteristic of charcoal, Unburnt vegetable
remains might be found carbonized, but would occur as splinters,
twigs, leaves, or seeds, none of which were seen. The only traces
of plants, besides the charcoal, were small vertical roots, represented
by fibrous ferruginous cylinders, too much decayed for microscopic
examination. The charcoal appeared to be crushed and trampled
into the soil, and the Authors had not yet been able to extract a
piece sufficiently large for the determination of the wood, although
the cell-structure was well preserved.

The Authors would not hke to speak confidently as to any one of
the stones exhibited being an implement; but the evidence was
cumulative. The common occurrence of vein-quartz in a layer
containing hearths of the fire-resisting elvan, the discovery of
abundant crumbs of chareoal, the stratigraphical position of this
layer, which seemed to coincide with the Palxolithic layer of the
Hampshire coast, all pointed to the presence of man. If these rude
tools were not implements, then we were confronted by the strange
occurrence of numerous signs of human cecupation, but no associated
implements.

Vol. 60.] AN EOCENE OUTLIER OFF THE CORNISH COAST. 113

9. On the PROBABLE OccURRENCE of an Kocenr Ovruier off the
Corniso Coast. By Crement Ret, Esq., F.R.S., F.L.S., F.G.S.
(Read March 9th, 1904),

Durine the new geological survey of the Hampshire Basin fresh
evidence was discovered of the westerly extension of certain of the
deposits, in the form of Eocene river-gravels.? This evidence tended
to link more closely the Eocene deposits of Devon with those of
the Hampshire Basin; but it did not seem to throw any hght
on the Eocene geology of Cornwall, nor of any part of the area
west of Dartmoor.

Some years since (in 1897) during a holiday-visit to the Lizard,
I was much impressed by the character of the material which forms
the extensive shingle-beach at Gunwalloe, on the western side of the
Lizard promontory, not far from Mullion. The shingle, which was
being extensively carted away for gravel, was so perfectly rounded,
and in appearance was so unlike anything that I had expected to
find in Cornwall, that I examined it closely, taking away samples
to give to the Museum of Practical Geology, Jermyn Street. The
coarser beach proved to consist largely (about 70 per cent. by weight)
of Chalk-flint and Greensand-chert, only 30 per cent. being Paleozoic
at the spot where it was examined. A large quantity of the fine
shingle yielded :—

per cent.
Ohratle tint so ncscedmeneer siwdalen 860
Greensand-chert.................- 2:0
SE le aston, Sere thand Se ip ae 9:0
Gare. kl easier eee oe 2°5
PeMpenbine’ W700... Saest oe steen sone 05
1000

At the time, I was unable to carry the matter further; for,
although well aware that scattered Chalk-flints were not uncommon
in Cornwall, I could not understand why so many had collected at
this spot, almost to the exclusion of the local rocks, The absence
of Chalk-flints from the Pliocene gravels of St. Erth seemed to
suggest that the Mullion gravel might be a Pleistocene deposit of
glacial origin, or derived from some such deposit.

In 1901 and 1903, during the completion of the maps bordering
on Mount’s Bay for the Geological Survey, an opportunity was
given for an examination of the deposits of Chalk-flint which are
known to occur in the neighbourhood of Penzance, especially in

* Communicated by permission of the Director of H.M. Geological Survey.
* «The Eocene Deposits of Dorset’ Quart. Journ. Geol. Soe. vol. lii (1896)
pp. 490-95 ; & ‘ The Eocene Deposits of Devon’ ibid, vol. liv (1898) pp. 234-36.

Q; J. G. 5. No. 238. I

114 MR. CLEMENT REID ON A PROBABLE [May 1904,

Ludgvan. An excellent description of these deposits was given, as
long ago as 1758, by William Borlase, the Cornish geologist, who
was rector of the parish in which they are found. His account is
as follows :—

‘It has been generally held by Naturalists that we have no fiints native in
Cornwall, but this is a mistake. Betwixt the towns of Penzance and Marazion
there is a beach of pebbles two miles and three quarters long, among which
many hundred flints may be picked up every day; and lest it should be in-
sinuated that these flints may possibly be foreign, and brought in ballast by
ships, I must observe, that in the low-lands of the parish of Ludgvan, scarce a
musket-shot from the said beach, in a place called the Vorlas, there is a
stratum of clay about three feet under the grass: the clay is about four feet
deep. In this clay, immersed from one to four feet deep (sometimes deeper)
flints are discovered in great numbers, their size from the bigness of a man’s
fist to that of a bean, their coat nearly of the colour of the clay, (as in chalk
we find their exteriour infected with the chalk-bed in which they lie) and their
inward part died with the same colour more than half way; the other part,
near the middle, a common, corneous, brown flint. In the same bed of clay, I
find sea-pebbles of opake white quartz,and some shingle ; sufficient and evident
vestiges of the universal deluge. I find also many small blue killas stones,
with all their angles on ..,. The flints of this bed of clay are brown within,
but on the beach we have a remarkable variety, and one now before me of an
opake white, is of as fine texture, and as high a polish, asany Carnelion I have
ever seen’ [probably the chalcedonic Greensand-chert of Haldon].’

The gravel is still dug at the place that Borlase names ; it occurs,
as Borlase pointed out, away from the sea and above the sea-level
(usually 20 or 30 feet above), therefore it cannot be accounted for
by any transportation as ballast. Though the name ‘ the Vorlas ’
is now forgotten, the old gravel-pits will be found on the landward
side of Marazion marsh. In the small pits now open the flints
are subangular, often up to 2 or 5 pounds in weight, and are mixed
with Greensand-chert and a considerable amount of the local
Paleozoic material, in a matrix of sandy loam. The origin of this
loam, which is certainly not the original matrix, I do not propose
here to discuss: it probably forms part of the raised beach which
fringes Mount’s Bay ; but the sections now seen are scarcely satis-
factory. It only concerns us here to point out that the large
quantity of flint-gravel is not ballast, but was apparently there
before the land was inhabited.

Certain striking characteristics of these flints seem not to have
attracted the attention that they deserve. Though so far from
any exposure of Cretaceous rock, they are subangular; and they
are weathered and ‘annealed’ in the same curious way that is seen
in the flints of the Eocene gravels of Devon and Dorset. In fact,
the resemblance of the material to that of Haldon is so striking,
that I feel sure that both flint and chert are derived, not directly
from Cretaceous rocks, but through the intermediary of some
Eocene river-gravel, such as was described in the two papers
already published.

So far as we know, there is no reason to suppose that any Eocene
outlier still exists in the county ; but the curious localization of an

1 *Natural History of Cornwall’ folio, 1758, p. 106.

Vol. 60. | EOCENE OUTLIER OFF THE CORNISH COAST. 115

‘extensive deposit of angular Chalk-flints at Ludgvan, and the
oceurrence of a mass of beach-pebbles of the same flints to the lee-
ward at Mullion, convince me that an Eocene outlier is preserved,
or lately existed, under the sea not far from St. Michael’s Mount.
The stones from this deposit were probably thrown up by storms
and carried up entangled in seaweed, until they formed a considerable
part of the raised beach opposite. They were also dritted by the

Fig. 1.— Map of South- Western Cornwall, on the
scale of 6 miles to the inch.

Above 400 Feet. 2
200 —400 Feet.

Below 200 Feet.

Wolf Rock

prevalent wind right across Mount’s Bay, becoming smaller and
more rounded, till they were reduced to the smooth bean-like pebbles
which we find at Gunwalloe.

The curious distribution of the flints, which elsewhere in Corn-
wall seem to occur only as scattered ice-borne erratics, combines
with the striking contour of the bay (see fig. 1) in which the
angular flints occur to localize the outlier; but there is a further

piece of evidence, of which the bearing was not at first seen.
12

Fig. 2.—Diagrammeatic section across the St. Erth Valley (Cornwall).

S:E:

onning
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Trenerom

Trink

Ail

Rosewall
Hill

N.W.

Near
St Erth

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SLATE &C.

[Length=about 10 miles; the vertical scale is 10 times the horizontal. |

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= ~-

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Lee \77\) SESS

While examining the Plio-
cene deposits of Cornwall
in 1886, I was puzzled to
account for the valley
(fig. 1) which crosses Corn-
wall from north to south,
from St. Ives Bay to
Mount’s Bay, almost iso-
lating the Land’s-End dis-
trict. This depression is
partly occupied by Pliocene
strata; but it obviously did
not originate in Pliocene
times ; it is something older,
something that does not
fit in with the late-Tertiary
denudation of Cornwall.
A more extended know-
ledge of Cornish geology
suggests that this Phocene
strait was once an Eocene
river-valley, now so trun-
cated at both ends that we
cannot say whether it ran
from south to north or
from north to south.

The diagrammatic section
(fig. 2) shows the relation
of the Land’s-End mass to
the rest of Cornwall. It
will be noticed that at
about 400 feet above the
sea there is a_ strongly-
marked shelf, or plane of
marine denudation, of Plio-
cene date, this plane bear-
ing no fixed relation to the
limits of the granite. The
upper boundary of this
plane is a degraded cliff,
which may cut obliquely
across any geological boun-
dary. The Pliocene shelf is
a striking feature through-
out West Cornwall, espe-
cially on the windward side.
But the Plocene deposits
are not confined to this
shelf, patches being found
near St. Erth at a much
lower level, near the bottom
of the wide open valley,
which existed before the
notch was eroded in its

Vol. 60.] AN EOCENE OUTLIER OFF THE CORNISH COAST. 117

‘sides. The notch is the plane of marine denudation which was
formed in Pliocene times near the sea-level; the parts of the
pre-existing valley below that level, either remained unaltered, or
tended to fill up with Pliocene sediments, outlying patches of
which are still preserved.

The occurrence of an Eocene outlier at a low level opposite the
southern end of the valley just described, suggests that the river
flowed from north to south (more exactly from north-east to south-
west); but this evidence is by no means conclusive, for we must
remember that Miocene earth-movements played an important part
in the Hampshire Basin, and disturbances of this character may
have extended into Cornwall, quite altering the drainage.

The little evidence yet available suggests that Eocene rivers
radiated from the high ground of Dartmoor, flowing westward as
well as eastward, and that one of these rivers turned southward to
cut through the depression leading to Mount’s Bay.

Whether the Eocene gravel which seems to occur beneath the
waters of Mount’s Bay is a mere isolated patch or no is not clear.
It may be an outlier belonging to an extensive Tertiary basin
underlying the western part of the English Channel, and comparable
in importance to the Tertiary basin of Hampshire. I would not
venture to make this suggestion, were it not for a piece of evidence
which cannot be ignored ina paper dealing with the Eocene geology
of West Cornwall. Some 20 miles south-west of St. Michael’s
Mount lies the isolated mass of phonolite known as the Wolf Rock,
on which stands the: celebrated lighthouse. This volcanic rock has
been a standing enigma to the geologist: there is nothing like it in
Cornwall, the only lavas of this type in Britain being of Paleozoic
date, and occurring in Ireland and Scotland. On the Continent the
phonolites are mainly Tertiary. It has already been suggested by
more than one writer that the phonolite of the Wolf Rock may be
of Eocene date, for, unlike the Palzozoic igneous rocks of Cornwall,
it is neither altered nor sheared." The occurrence of a lava of this
exceptional type, thus placed in the course of an Eocene valley,
may perhaps be pointed to as a confirmation of the view that an
Eocene basin may lie under the sea in the western part of the
English Channel.

Discussion.

Prof. W. W. Warts observed that one of the many interesting
points of the paper just read was connected with the occurrence of
phonolite at the Wolf Rock, at one time regarded as unique in the
British area. Geologists had long been searching for evidence as to
the date to which it could be assigned. However, Dr. Hatch had
since discovered Carboniferous phonolite in the South of Scotland,
and the speaker had discovered one associated with Carboniferous

1 §. Allport, ‘On the Microscopical Structure & Composition of a Phonolite
from the Wolf Rock’ Geol. Mag. 1871, p. 247; and ‘ Note on the Phonolite from
the Wolf Reck’ ibzd. 1874, p. 462.

Lis MR. CLEMENT REID ON A PROBABLE [May 1904,

rocks, but possibly of later date, in the South of Ireland. If the
Tertiary age of the Wolf Rock were proved, then it must belong
to a distinct petrographical province, as all other Tertiary igneous
rocks in the British area were free from nepheline.

Mr. H. W. Monckton said that the decayed flint-pebbles exhibited
by the Author were very unlike the black and singularly well-
preserved flint-pebbles characteristic of the Eocene pebble-beds of
the London Basin. At Highcliff, near Christchurch, however, there
were, no doubt, decayed flints in a Bracklesham pebble-bed.

Mr. P. F. Kenpatt said that the origin of the superficial deposits
of Cornwall had given rise to much speculation and controversy.
He did not think that the Author had offered very conclusive proofs
of the age of the deposits, but he could not altogether agree with
the previous speaker. The most corroded flint-pebbles that he had
ever observed were from an excavation in Blackheath Beds at Mile
End. They were actually pulverulent, yet distinct and charac-
teristic. He had not understood the Author to imply that all the
pebbles in Eocene deposits were corroded, but that such altered flints
were characteristic of Eocene rather than of Pleistocene gravels.
The paper constituted a bold attempt to solve the problem of the
widely-extended deposits of subangular pebbles in Southern England
and Southern Wales. He did not think that the phonolite of the
Wolf Rock had any very direct bearing on the question. Prof. Cole
had pointed out that the volcanic rocks cf Ardtun, in Mull, were
exceedingly rich in alkalies, and further search would possibly
reveal the presence of phonolites there.

Dr. A. KE. Sarrer asked whether the Author had detected fragments
of any other materials, besides Greensand-chert and flints, similar
to those found in old river-gravels, derived from the Dartmoor area
to the east, as, for example, at Hardy’s Monument (Dorset). The
speaker had searched in vain some few years ago for evidences of a
western drainage from Dartmoor, in Cornwall. On Crouza Down, in
the Lizard district, at an altitude of akout 360 feet above sea-level,
is an extensive deposit of gravel, but the rolled fragments consist
mainly of quartz. He agreed with previous speakers in doubting
the advisability of relying upon the degree and manner of weathering
of flints as evidence in proving the Eocene age of a deposit.

Mr. H. B. Woopwarp, adverting to the striated stone from the
Scilly Isles exhibited by Mr. Barrow, asked whether the Author
could not account for the transport of the accumulations of flints
by some form of ice-action.

Mr. Barrow remarked on the curious distribution of pebbles in
the Scilly Isles, some of them being found up to the highest levels
on St. Martin. The noteworthy hollow which extends from St.
Ives to Mount’s Bay is a phenomenon repeated over and over again
in the Scilly group.

Mr. Wurraker objected to calling most of the stones exhibited
‘ pebbles,’ as they hardly deserved that description. Despite the great
mass of the pebbles in the Eocene of the London Basin being black
flint, there were exposures where decomposed flints were found, and

Vol. 60. | EOCENE OUTLIER OFF THE CORNISH COAST. 119

' these in old descriptions of Eocene sections were termed (wrongly)
‘Chalk-pebbles.’ It would be remembered that in the Chalk itself
there were decomposed or ‘ thick-skinned’ flints. He took it that
the Author regarded the Eocene of Cornwall as consisting largely of
river-gravels. In such deposits we must expect variety rather than
a monotonous uniformity.

The AvrHor, in reply to Mr. Monckton, thought that the
characteristic internal alteration noticed in flints from Eocene
deposits was not confined to the Hampshire Basin, but was equally
common in the neighbourhood of Londen, at Highgate, Hampstead,
and Stanmore. It could not be described properly as ‘ weathering,’
for it was apparently a change that took place while the flints were
embedded in the sandy or clayey matrix.

In reply to Mr. Kendall, he thought that the perfect rounding of
the Cretaceous material in the beach of Gunwalloe was due to the
drifting of the flints, for 15 or 20 miles across the bay from near
Marazion, where the flints were both subangular and larger.

Mr. Woodward’s suggestion that these angular flints might have
been brought by drift-ice would not explain their occurrence in
large quantities at one spot, while bays on either side only yielded
the flints sporadically. These sporadic stones, in all probability,
pointed to the agency of drift-ice in Mount’s Bay in Pleistocene
times, as did the striated erratic from Scilly exhibited by
Mr. Barrow.

120 MR. A, MONTGOMERIE BELL ON [May 1904,

30, ImpLemENTIFEROUs Sxrctions at WoLVERCOTE (OXFORDSHIRE).
By ALEXANDER MonteomMERTE Bett, Esq., M.A., F.G.S. (Read
January 6th, 1904.)

A seEcrion at Wolvercote, a village 14 miles north of Oxford, has
been open for the past ten years, and will reward study by geolo-
gists interested in the phenomena of Pleistocene time, whether their
object is to study the changes of land and climate, or whether, as
was the case with the writer, they seek for some detail in the
fragmentary story of Paleolithic Man.

The section contains four parts, which may thus be named in the
order of their age: (1) the Oxford Clay beneath, which is largely
quarried for bricks; (2) an old surface, in which pits or troughs
chiefly filled with gravel are seen enveloped in weathered clay ;
(3) a river-bed, containing gravel at the base, and layers of variously-
coloured clay above; and (4) a surface-layer of humus oyer all,
about 2 feet thick, containing Neolithic remains. The relation
which the various parts bear one to the other is also plain. The old
Pleistocene surface lies upon eroded Oxford Clay ; the river-bed
has worn a channel in the old Pleistocene surface; between the
river-bed and the Neolithic surface is the trail usually named
‘warp, which, however, is not discussed in this paper.

The river-bed first attracted my attention ; it iies on the summit
of land between the Isis and Cherwell, at an equal height above either
river. There seems to be no reason to doubt that it represents the
deposits of a stream which contained the united waters of both
rivers, at a time before they became separated to their present levels
by the erosion of the soft clay. The channel is 17 feet in depth
from the present surface to the clay beneath ; it is seen descending
on the western side from about 3 feet from the surface to 17; it
has a considerable breadth, as about 40 yards of the old bottom
are visible, and the bank of the stream on the eastern side is not
laid bare.

The riverine section itself has two parts: at the base, to a
depth of about 245 feet, is a bed of gravel and sand, largely current-
bedded, and containing many quartzite-pebbles of medium size.
There are also exceptional stones, about 2 feet square, both of
quartzite and of sandstone.' A quartzite-stone of this size, but
little weather-worn, is an anomaly in the Thames Valley, though
its appearance in the river-bed requires no further explanation than
deposition from river-ice, or from the roots of a floating tree in
which it had been embedded. The lighter stones point north and
south, showing that the current flowed in the same direction as the
present Isis and Cherwell.

At the top of this gravel-bed was a thin lenticular layer of

* It has been suggested to me that these may be greywethers, but the sand-
stone is probably Lower Greensand.

Vol. 6o. | IMPLEMENTIFEROUS SECTIONS AT WOLVERCOTE. 121

' peat and sand, not more than 2 inches thick. Mr. Clement Reid,
F.R.S., examined a portion of it, and rightly described it not as
originally having been a land-surface with vegetation growing upon
it (which I had at first thought it to be), but as a water-surface, which
had caught and deposited in a backwater a number of plant-remains
floated down the stream. It is material to an examination of the
bed that this layer, now below 15 feet of soil, must at the time of
its formation have been at the surface of the water. Peaty sub-
stance would not form at the bottom of-a flowing stream.

The 15 feet of strata between the gravel and the present surface
have a different appearance. They are conformable to the gravel
below, and have been laid down by water, as is manifest from the
long and even lines of deposition. But there is no gravel and little
sand, only successive layers of mud or clay—sometimes blue Oxford
Clay, very little altered, at others the layers are coloured yellow and
red by the oxidation of iron. The whole upper part has the appear-
ance of having been laid down in a lake, or in a large river-pool,
but not in a running stream such as deposited the gravel below the
lakes. Prof. Phillips? wrote, no doubt correctly, of lakes which
had existed and disappeared in the earlier stages of the formation
of the Thames Valley. The position at the head of the gorge at
Goring is one that naturally suggests a prehistoric lake; and at the
present day it forms a lake in times of flood. ‘The Wolvercote site
in its present condition bears no resemblance to one where a lake
would be likely to form, as there is a natural fall in the ground to
the eastward, the direction of the stream, and there are no approach-
ing spurs of higher ground on either side. If we consider that the
beaver was a tenant of the valley in Pleistocene times, we have, I
think, no improbable reason for the surface of the stream to have
risen in height, and for the formation of a poo] instead of a running
stream. Beavers’ dams are sometimes 300 yards in length, and a
barrage of this size would completely account for the change visible
in the section. Had I found fossil remains of the beaver in the
bed, I should have offered this explanation of the upper part of the
section without any hesitation. I have, however, found neither
beaver nor anything else in this portion of the section; nor have I
seen remains of the beaver except in a Neolithic peat near Faringdon.
At the same time, the beaver was a Pleistocene creature, and his
influence in altering a river-landscape was probably at that epoch
little interfered with by man. Even in later times the influence of
the beaver should be looked for; probably many flat plains upon
the reaches of our rivers owe much of their form to the handiwork
of this busy creature in the Neolithic and early historic ages.

To complete the description of the river-bed, it should be added
that the Oxford Clay beneath the gravel is curiously pitted. This
gravel does not lie in a horizontal plane above the clay, but fills
innumerable contiguous pits measuring about 3 feet in diameter
and 1 foot in depth. The clay beneath the deposit which I have

* © Geology of Oxford & the Valley of the Thames’ 1871, pp. 462-63 & 468.

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Vol. 60.] | IMPLEMENTIFEROUS SECTIONS AT WOLVERCOTE. 123

named the ‘ older surface’ is not pitted in this manner, so I attri-
bute the phenomenon to a form of river-action, which I am unable
to explain.

The Associated Fossils.

The gravel-bed has proved richly implementiferous. The imple-
ments are formed of flint taken freshly from the Chalk, or of
quartzite-pebbles of the Northern Drift, and they are remarkable
for their size, beauty, and freshness. As usual, they have a facies
of their own; the oval type is rare, and the pointed examples are
very frequently flat or nearly so on one side, belonging to what Sir
John Evans has named the ‘ shoe-shaped’ type.

Many of the usual mammalian remains are also found: Hlephas
primigentus, Equus caballus, Bos primigenius, Cervus elaphus, are
all of frequent occurrence, and Rangifer tarandus has been once
obtained. For smaller mammals I have searched, but unsuccess-
fully. Neighbouring gravels at a lower level, but probably of
similar age, have yielded examples of Rhinoceros, Hippopotamus,
and /élis leo, var. spelwa.

In the sand mixed with the gravel were found a number of
fluviatile shells, of which eleven species were identified by the late
Prof. A. H. Green and his assistant. They did not include the
distinctive Corbicuia fluminalis, which does, however, occur at
several places in the neighbouring gravel about half a mile distant.

The layer of peat has also disclosed some of its treasures. It
cannot be separated as to age from the gravel beneath it, for it
contains the fragments which floated on the water of which the
gravel formed the bottom. The late Prof. Green associated it with
the implementiferous gravel, with which it was conformable in
deposition and in the shells contained in both. It was also con-
formable to the water-formed layers above ; all three (gravel, peat,
mud) formed portions of a single deposit, clearly marked off by the
warp above from the Neolithic layer of the surface. It is necessary
to say this, because Mr. Clement Reid’ regards the deposit as ‘ of
uncertain age.’

While disagreeing with him on this point, I am sincerely grateful
for his courtesy in identifying the flowering-plants found in the
bed. ‘They are thirty in number, and include four species of Ranun-
culus, three of Potamogeton, three of Carex, two of Scirpus, also
Zannichellia, Ajuga, Lycopus, Heraclivum, Thalictrum flavum, a
Rumex, Hippuris, and Betula. This list contains nothing distinctive,
nothing characteristically northern or characteristically southern,
but it harmonizes very well with the flora obtained by Mr. Reid
from deposits which he names Interglacial. From the animals
with which they are found, the natural inference is that the plants
belong to that great section of our flora which entered our island—
then a portion of the Continent—from Eastern Europe and Western
Asia, coming at the close of a great glaciation to cover with verdure
the lands which the ice-cap had left bleak and barren.

* *The Origin of the British Flora’ 1899, p. 85.

124 MR. A. MONTGOMERIE BELL ON [ May 1904,

The evidence yielded by the mosses is more remarkable, and
strengthens to certainty the inference derived from the flowering-
plants and animals. For identification of the moss-collection I
have to thank, first, Mr. A. Gepp, F.L.S., of the British Museum
(Natural History), who kindly looked over the first examples found ;
and, secondly, Mr. H. N. Dixon, M.A., F.L.S., of Northampton, who
took great pains to examine and name a large number of specimens
placed in his hands. The following list consists of Mr. Dixon’s
verifications :—

Amblystegium filicinum, De Not. Hypnum aduncum, Hedw.
A, Kochii, B. & 8. H. aduncum, var. pseudofluitans.
A. serpens, B. &. 8. Hi. capillifolium, Warnst.
Aulacomnium palustre, Schwegr. Ai. chrysophyllum, Boisd.
Brachythecium glareosum, B. & 3S. Hi. commutatum, Hedw.
Br. rutabulum, B. & 8. H. cordifolium, Hedw.
Bryum erythrocarpum, Schweer. H. cuspidatum, Schreb.
Camptothecium nitens, Schp. H. exannulatum, Gimb.
Climacium dendroides, W. & W. H. falcatum, Brid.
Dichodontium pellucidum, Schp. H.. fluitans, L.
Eurhynchium Schwartzii, Hobk. H. fluitans, var. falcifolium, Roem.
Eu. speciosum, Schp. H. giganteum, Schp.
Homalia trichomanoides, Brid. H. intermedium, Lind.
Mnium affine, Bland. H. lycopodioides, Schwegr. (doubt-
Mn. rostratum. ful).
Philonotis fontana, var. aimplirctis, H. revolvens, Sow.

Dix. H. Sendtneri, Schp. (probable).
Thuidium decipiens, De Not. A. stramineum, Dicks.

Th. recognitum, Lindb.
Webera albicans, Schp.
W. nutans, Hedw.

The list is interesting, and points to one of the largest collections
of mosses yet secured from a Pleistocene deposit. About two-thirds
‘of these mosses may still be found in the neighbourhood. This
corresponds with the flowering-plants. On the other hand, Hypnum
capillifolium, Warnst., is not now found in Britain, and has only
once been obtained before, from a deposit at Mundesley, where
it was got from the Arctic Freshwater-Bed at a depth of 59 feet.
This species of moss now occurs in Siberia, in Central and Northern
Europe, and in America in Vancouver and other northern regions.
‘It is not, however, recognized as a boreal plant.

Thuidium deciprens, De Not., is perhaps equally important. It is
‘a rare moss, found in wet places on mountains, and in this country
confined to the Highlands of Scotland. ‘These are the two most
important ; one denoting an Alpine plant, another a plant no longer
British, and closely approaching the Alpine flora.

Ot the others the following are no longer found in the county
of Oxford :—Camptothecium nitens, Schp., Dichodontium pellucidum,
Schp., Hypunum gigantewn, Schp., H. revolvens, Sow., H. straninewn,
Dicks, which all occur in mountainous or subalpine regions.

Seven at least of the species identified no longer grow in the
‘county : one has left Britain, and a second has retired to the Scottish
Highlands.

Some conclusions doubtless may be legitimately drawn from these

Vol.60.] | IMPLEMENTIIFEROUS SECTIONS AT WOLVERCOTE. 125

_facts:—(1) The Glacial flora had not entirely withdrawn. It is
still marked by one, if not by two species. (2) The land was
more elevated than it is now; the considerable percentage of moun-
tainous species seems to call for this conclusion, which on other
grounds is also demanded. (3) The land appears to have been very
wet, almost waterlogged. A high rainfall is also called for by
many phenomena of Pleistocene time, and would follow from the
previous conclusion. If the Cotteswold water-parting were from
400 to 600 feet higher than it now is, the rainfall of the Thames
Valley would undoubtedly be greater than the channels can properly
deal with. (4) From the number of now-existing species I infer a
warmth of climate fully equal to that of the present day.

A collection of elytra and other parts of beetles was also secured,
numbering probably 30 species; these have not, as yet, been
determined.

In the lacustrine or still-water portion no fossil has been found.
Fragments of shells are here and there visible, but no fragment of
wood or bone, or determinable plant.

The deposit as a whole is a typical river-valley deposit.
Implements, mammalia, mollusca, flora, all are characteristic of
such a formation as Sir John Evans describes in the 2nd edition
(1897) of his well-known work on the ‘ Ancient Stone-Implements
of Great Britain’ (pp. 662, 679, 686) :—

‘T have made no scruple in treating them hitherto as being river-drift. . . . .
The character of the beds, consisting as they do, of gravel, sand, and fine silt,
brickearth or less, and their manner of deposition, are also absolutely in
accordance with the river-hypothesis. ..... The discoveries in the gravels
capping the North Downs, and those made near Ightham and Limpsfield in
the transverse valley at the foot of the Downs, seem at first sight difficult to
reconcile with any river-theory. But, assuming that the beds capping the hills
were at one time continuous with others in the Wealden area, and that the
transverse valley was produced by denudation at a later date, the difficulties
disappear.’ ‘

His general theory is, that practically all implementiferous de-
posits are of a similar character and of fluviatile origin.

It appears to me, however, that the other part of this section
affords convincing evidence of an earlier stage of Paleolithic life,
not preserved in a river-gravel. The previous surface already men-
tioned (p. 120), which has been wasted away where the river-gravel
lies, is instructive. Before describing the section, I should like to
quote the words of the late Prof. A. H. Green. On my going with
him to the spot, after I had found implements beneath the peat-bed
above described, he said :—

‘T have never paid particular attention to Paleolithic gravels for their relation
to human remains, but I have often visited this section for another purpose.
You observe the remains of an old surface which has been hollowed out by a
river. You see hollows in the clay filled by pebbles of the Northern Drift.
All these pebbles you will find re-arranged in the bottom of the river-bed, and
I have often brought my pupils here to show them how a newer bed is formed
by the destruction and re-arrangement of an older deposit. . . . You have not,
I imagine, found implements in the upper gravel or old surface ?’

126 MR. A. MONTGOMERIE BELL ON [May 1904,

I replied that I had not: that I had examined the exposed parts,
but found nothing. He remarked that it was unlikely that I should
find them.

This previous surface has now proved to be implementiferous ;
there are side by side two implement-bearing deposits, different in
character and different in age.

This surface consists of a series of troughs formed in the clay,
and filled with gravel, sand, and earth. The stones which the
troughs contain consist largely of quartzites, lydian-stone, and
quartz-pebbles. These pebbles all belong to the ‘ Northern Drift,’
by which name Prof. Green told me to style the deposit. In this
Prof. Phillips would, I imagine, have agreed with him. In the
‘ Geology of Oxford & the Valley of the Thames’ (1871) pp. 457-58,
Phillips wrote :—

‘To these I assign the title of Hill-deposits, not that they are exclusively
found on elevated ground, but because this fact is characteristic of them, in
contrast with the others. Scattered materials of these hill-gravels are often
found in low ground mixed with those in the true valley-deposits, under
circumstances which indicate the anterior date of the former.’

This exposure was not expressly mentioned by Phillips, although
it was in his time exposed in a railway-cutting, which adjoins
the section now under discussion. At the same time, besides
the northern pebbles, we also find in the troughs much gravel
from the Thames Valley, hmestone-pebbles, and Oolitic fossils,
together with sand. The presence of these materials has led me to
regard the Drift as not the true Northern Drift, which caps the
hills around at a level of about 500 feet, while the Wolvercote level
is 240 feet, but as a Thames-Vailey Ice-Drift, consisting largely of
a remaniment of the Northern Drift.

The Wolvercote Drift shows itself in somewhat flask-shaped holes
in the clay, filled up by gravel, and with columns of clay between,
still attached to the unbroken Oxford Clay beneath. The question
arises as to how such a drift is formed. Is it a drift of rainwash? :
or is it perchance no drift at all, but the result of underground water
forming holes in the clay, which are filled up by the infall of surface-
stones? ; or, again, is it an ice-drift ? It is not a rainwash-drift,
because, if it were, it would not have narrow inlets at the top, which
spread out beneath, but would be spread out over the surface, with
slight traces of bedding. Nor has it been caused by underground
water, as the action of water would be visible at the lowest point
where the flow was continuous; the stones at the sides would
also have a tendency to drop towards the centre, when the stream
was carrying away material. There are no traces which lead me
to attribute it to this cause.

It is otherwise when the ice-drift hypothesis is tried; for here
there are several salient facts which find an explanation. The
troughs are fan-shaped. The pebbles in the centre have their
longer axes pointing downward, while at the sides they are
horizontal. This seems to show that they were pressed down
by a weight above them, which, as it forced them to move into the

Vol. 60.| | IMPLEMENTIFEROUS SECTIONS AT WOLVERCOTE. 127

‘yielding clay on the sides also, caused them there to take up a
horizontal position, along the line of least resistance.

Again, the material is not only free from any bedding, but
lumps of sand are stuck in beside masses of Thames gravel in
a manner which suggests that they were frozen or half-frozen
when they were shoved in; otherwise it is hard to account for
the oblong lumps of sand.

Another circumstance was to my mind decisive, both as to the
age of the Drift in relation to the gravel-bed, and the nature
of the cause to which the Drift is due. It is this: the Oxford
Clay beneath the Drift is weathered to the depth of about 10 or
12 feet : it seems to have been shaken, and penetrated so far by
surface-water. This line of weathering is constant beneath the
Drift; and when it approaches the gravel-bed, it goes under it
for a certain distance until it is cut off by the descending depth
of the river-gravel. Beneath the deeper part of the old river-
valley the blue clay is quite unweathered. Three facts are here
proved: (1) The weathered band of clay was older than the ancient
river, because the river destroyed it; (2) the force of the river
did not weather the clay beneath; (3) the force of the Drift did
weather the clay, and must consequently have been a heavy and
a powerful force. A rolling drift of ice, snow, stones, and mud
would be heavy and powerful, and might, I think, act so as both to
shake the clay beneath and to shove portions of its own gathering
mass into the softened clay beneath its passage. This, at least, is
the only explanation of the section that I can suggest as satis-
factory. I consider it to be an ice-drift, and to mark an important
epoch in the Glacial Age.

At a distance of about half a mile, at a place called Peartree
Hill, and on an elevation similar to that of Wolvercote, there is
another section of the Drift (see fig. 2, p. 128). Its features are
quite similar to those which I have described; it also contains
implements, and the clay beneath it is also weathered and shaken
in the same manner as the clay at Wolvercote. There is at Pear-
tree Hill no trace of any river-action: there is solely the Drift.

From the Drift at Wolvercote no fossil has been obtained, except
the implements, which constitute at least a trace of life. From
Peartree Hill I have obtained from a workman (and the staining
corresponds with the gravel) the canine tooth of a wolf—an un-
satisfactory fossil, as it gives no indication of the age of the gravel.

The implements obtained from the two beds are in two wavs
distinct. Those found in the river-bed are very large, of beautiful
shapes, of chalk-quarried flint, and very little stained. Those from
the Drift are small, of very ordinary shape, formed of flint taken
mostly, if not altogether, from the Drift. To the simplicity or
rudeness of form I do not attach much importance : partly, because
few implements only have been found, not a sufficient number on
which to base a general judgment ; partly also, because very
simple forms are found in use throughout all Paleolithic time;
partly, because very beautiful forms of implements occur in other

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Vol. 60. | IMPLEMENTIFEROUS SECTIONS AT WOLVERCOTE. 129

‘gravels, which it is difficult to believe of later age. It is of some
importance if an implement has been made from a weathered
pebble of the surface. When I first began to collect and examine
these tools in the parish of Limpsfield in Surrey, where they lie
largely on the surface, I found two classes, often very distin-
guishable—tools of surface-flints, and later tools of quarried flint.
This distinction appears again in Oxfordshire, and is probably of
some importance.

The last distinction is one which I must consider of great
importance. The river-bed flints are slightly weathered, or not
at all; while the Drift-flints are deeply weathered, white or
brown, usually all over, always at least partially. Flint-fragments
from the river-bed present a totally different appearance from
fragments taken from the Drift: from the river-bed they are black
or transparent; from the Drift they are ochreous and opaque.
This is an important fact; and I draw from it two inferences,
which are also important and may provoke discussion. I was told,
twenty years ago, by one of the fathers of this study :

_* From the weathering of a flint no inference can be drawn. I have fre-

quently found in the same bed, side by side, worked flints—one quite fresh,
the other weathered and worn.’

This silenced me at the time; but a proper answer would have
been :

‘Yes; but your two flints were not of the same age. The unweathered flint
was contemporary with the bed where you found it; the weathered one
originally lay in another bed, where it. was stained; it was dislodged after
a long burial, exposed and rolled, and finally deposited in a fresh bed, where it
was a fossil detached from an earlier deposit.’

It is certain that the weathered character explains many diffi-
culties in classifying implements. For example: at Iffley, a mile
below Oxford, there is another implement-bearing gravel. It
stands at a lower level than those previously described ; its base is
very nearly on a line with the surface of the present river, about
300 yards distant. It is consequently of a later age than either of
the Wolvercote deposits ; but it does not follow that all its contents
are of a later age, or contemporary with the deposition of the
gravel-bed in which they he. Quite the contrary; it is an omniwm
gatherum of all the débris that ever rolled in the Thames Valley :
Oolitic fossils, Cretaceous fossils, Tertiary conglomerate, Northern-
Drift quartzites, jaspers, and volcanic rocks, gravel, and sand. When
in this gravel an unweathered implement occurs, I think that I am
justified in correlating it with the unweathered river-bed imple-
ments of Wolvercote ; whereas, if the implement has an ochreous
staining, I consider that it once belonged to the Drift-bed, of
which so few fragments now remain im situ. Such an inference
encroaches upon certainty: I feel inclined to add that all ochreous
or deeply-patinated implements are of the same or similar age,
wherever they are found.

My second inference is, that the time between the Drift and the

Q.J.G.8. No. 238. K

130 MR. A. MONTGOMERIE BELL ON [May 1904,

river-bed was prolonged ; that there is a great interval, perhaps as
great as that which separates the river-bed from ourselves. The
evidence consists in the patination of the two groups of flints. We
must remember that these two groups of flints lie under similar
influences; they are both in gravei and sand; they are both
permeated by water depositing carbonate of lime and oxide of
iron. Why should they be so completely different—one class
deeply patinated, the other little altered? Why were they as
deeply patinated when the second stage began as they are now?
They seem to have been so, from the evidence of secondary work
on the edges of ochreous implements. I, at least, cannot explain
it, except on the supposition that the ochreous class has been
exposed to weathering influences for a far greater length of time
than the other: in other words, that there is a great gap between
the two beds. If the Drift-bed has been rightly attributed to
a return of cold conditions, and if the return of cold conditions
destroyed all the ordinary fiora of the country, then the return
of the flora, so marked a character of the river-bed, would be a
kind of measure: it would mean that between the first bed and the
second practically the whole of our recent flora had returned to our
shores.

I endeavoured for many years to work on Sir John Evans’s
theory of river-action alone. If I may be allowed to give my
present hypothesis, it 1s that implement-bearing deposits are of
different kinds, and fall into three classes:—(1) River-gravels,
which Sir John has eloquentiy described. (2) Rainwash-drifts;
which occur at high or low levels under circumstances well
described by Mr. Clement Reid in the following words’:

‘The South of England, during the second period of glaciation, seems to have
suffered from dry, cold winters, which froze the ground unprotected by snow,
and allowed the summer rains to fall on soils rendered impervious by deep
freezing. This led to enormous and rapid denudation, over areas where the
rain now sinks in and is slowly given out as springs. Masses of loose flint and
chalk-débris were swept off the South Downs, and spread out in a wide sheet
extending several miles over the lowlands.’

If any geologist, with these words in his mind, will examine the
section at Knowle Farm, in Savernake Forest, he will find in them
a fitting explanation. The gravel is loosely thrown together, and
has no horizontal layers ; the newest implements are fresh, and lie
at the base, where they were covered by the descending débris,
which frequently contains weathered and worn implements of earlier
age. It is a gravel caused by excessive rainwash on a sloping
hill, (3) These are ice-drifts, such as that which has been described
in the foregoing pages. I would set in this class the gravel-bed
of Limpsfield Common in Surrey, a deposit which, more than twenty
years ago, was the origin of my interest in these studies, and of my
resolution to grapple with their perplexities,

‘ «The Origin of the British Flora’ 1899, pp. 44-45.

Vol. 60.] fMPLEMENTIFEROUS SECTIONS AT WOLVERCOTE, 13]

DIscussIon.

Prof. Sornas congratulated the Author on the successful conclusion
to which he had brought his arduous and protracted labours. With
regard to the evidence of ice-action afforded by the Wolvercote pit,
he could not regard it, taken by itself, as conclusive. When the
Author had first shown him the curious disturbances in the Oxford
Clay, he had been much impressed by them, particularly when he
found in them the singular tea-leaf structure which was sometimes
associated with imperfectly-foliated Glacial clay; but, while sug-
gestive, the evidence was not demonstrative, for other agencies, such
as subterranean erosion, might conceivably have produced similar
results. The Author had also shown him flint-implements bearing
tine striz, but observations on implements from Amiens revealed
the presence of similar striz on them, and it remained possible that
river-ice or internal movements of the gravels might be responsible
tor these markings. In any case, the evidence had not been sufficient
to produce conviction either in himself or others. Later observations,
with which the Author had been made acquainted, on Shotover and
Cumnor Hills, had, however, thrown an entirely-new light on this
matter, and there could now be little doubt that the disturbances
in the Oxford Clay at Wolvercote were of the same nature as
those exhibited elsewhere in the district on a grander scale, which
were to be explained by ice.

The speaker thought that some attempt might be made at a closer
analysis of the problem than was implied by the use of the term
‘Paleolithic.’ Prof. Moritz Hoernes, from a review of the whole body
of evidence furnished by observations in Europe, had been led to
subdivide the Paleolithic Period into three stages, characterized by
their fauna, geological horizon, and state of culture: these are the
Chelléen-Moustérien, the Solutréen, and the Magdalénien. An
examination of the implements exhibited by the Author showed that
they were plainly Chelléen: there were no pointes A feuille de
laurier, no pointes a cran, nothing to remind one of Laugerie
Haute or Cré-Magnon, still less of La Madeleine. Therefore the
evidence from culture-stages would assign this find to the lowest
subdivision of Heernes. ‘lurning to the fauna, it was especially cha-
racterized by horse and mammoth, and thus should be referred to the
second stage. Finally, the terrace to which the gravels belonged was
the lowest in the Thames Valley, and must be referred by hypothesis
to the last inter-Glacial stage, or third subdivision of Heernes. They
were thus presented with a very remarkable problem—the three
characters on which Heernes depended spoke each with a different
voice —the implements pointed to Chelléen, the fauna to Solutréen,
and the geological horizon to Magdalénien.

Mr. Crement Rerp said that he had spoken of the flowering-plants
as of ‘ doubtful age,’ because they came from a deposit overlying the
implement-bearing gravel, and not from the same deposit as the
implements. Also, these plants were all species of wide climatic
and geographic distribution, and were still living near Oxford. The

K2

132 IMPLEMENTIFEROUS SECTIONS AT WOLVERCOTE. [May 1904,

determination of several species of boreal mosses showed that the
plant-bed was of Pleistocene date ; but it did not necessarily prove
that the plant- and implement-beds were contemporaneous.

Mr. P. F. Kenpart thought that Prof. Sollas had convincingly
demonstrated, either the entire unreliability of the Continental
classification, or its inapplicability to the succession in England.
Some of the implements could be matched with those from
Hoxne, which were of very late Glacial, perhaps the very latest
Glacial age. He concurred with the Author in believing that
Jand-ice had come down to the Thames Valley, and he had suggested
this himself some time ago.

The AvrHor thanked the meeting for the hearing which they had
given to his paper, and especially Prof. Sollas for acknowledging
the value of his work and correctness of his general conclusions.
With other English students he had not neglected the study of the
Moustérien, Solutréen, and Magdalenien epochs, but he, like others,
had failed to find in English deposits any traces of the same stages
of culture. This method, so successful in Southern France and in
Austria, had hitherto proved unprofitable in England. A_ better
one for our conditions had been adopted and patiently pursued for
twenty-five years by Mr. Clement Reid. His attempt had succeeded
in differentiating several important stages of the prolonged epoch, and
the ‘ Origin of the British Flora’ had been to the speaker a lux in
tenebris. He had, however, to acknowledge Prof. Sollas’s gentle
censure, and to apologize to his audience for broaching on partial
evidence such a subject as ice-action in the Thames Valley. No one
knew better than himself that so large a subject demanded to be
treated by corroborative testimony drawn from a wide area. This.
from lack of time, he had been unable to do. The main object of
his paper was to prove a distinction between two stages of Palzeolithic
life; he thought that he had done so by a convincing section, the only
thorough geological proof. Of corroborative evidence he had not
spoken, but it was so great that he had perhaps only given a definite
geological explanation of facts so generally acknowledged that their
solution was also generally surmised. He rejoiced to think that a
fuller treatment of the greater subject—the glaciation of the Thames
Valley—was in most capable hands, aud would ere long be dealt with
satisfactorily.

Vol. 60. | JAWS OF PTYCHODUS FROM THE CHALK. 133

11. On the Jaws of PrycHopus from the Cuatx. By ArrHur
Sire Woopwarp, LL.D., F.R.S., F.L.S., F.G.S., of the British
Museum (Natural History). (Read January 20th, 1904.)

[Pirate XV.]

Ix 1887 °* I pointed out that the teeth of Ptychodus from the Chalk
were arranged in the mouth not like those of the Cestraciont sharks,
but rather like those of some of the Myliobatid rays. This arrange-
ment has subsequently been observed in new specimens, both in
England and America.” Hitherto, however, no traces of the carti-
laginous jaws have been found in association with the dentition,
and their shape and relations have thus remained unknown. Quite
lately, a new specimen, partly showing the jaws, has been obtained
from the Lower Chalk of Glynde by Mr. Henry Willett, and he
has kindly submitted it to me for study, to supplement my former
description, which was chiefly based on the Willett Collection in the
Brighton Museum.

The new fossil evidently belongs to a small variety or young indi-
vidual of Ptychodus decurrens, the species previously discussed, and
its principal characters are shown in the accompanying plate (XV).
It comprises fragmentary remains of both jaws, each bearing many of
the characteristic teeth arranged in their naturalorder. The rami of
the jaw which may be identified as mandible (Pl. XV, figs. 1 & 2, md)
are remarkably slender, and meet in an acute angle at the symphysis,
which is shown to have been elongated, though it is disintegrated
by the formation and oxidation of iron-pyrites. The upper jaw or
pterygo-quadrate cartilage (fig. 2, ptqy) is represented only by shape-
less fragments. The dentition is confined exclusively to the sym-
physial region, where the teeth are arranged in the usual parallel
antero-posterior rows.

Of the lower teeth, some are preserved in natural order above
the hinder part of the symphysis, while a few are scattered in front
on the decomposed anterior end of the jaw. Of the large median
series (fig. 2, 0), three teeth are exhibited, displaying all the
typical characters of P. decurrens. To the left of these are teeth of
four paired lateral series (1-1v) in natural arrangement; while a
very small displaced tooth (v) seems to represent a fifth series at
the extreme outer border. It is to be observed that the dentition
does not curve backward at the side to spread along the mandibular
ramus, although the more laterally-placed teeth exhibit the usual
slight oblique distortion. If the larger scattered teeth on the sym-
physis belong to lateral series 1, as seems probable, it is also to be

1 «On the Dentition & Affinities of the Selachian Genus Pfychodus, Agassiz ’
Quart. Journ. Geol. Soc. vol. xliii (1887) pp. 121-50 & pl. x.

2 §. W. Williston, ‘Cretaceous Selachians { Pycnodonts’ Univ. Geol. Surv.
Kansas, vol. vi (1900) p. 239 & pls. xxv—xxvii.

134 DR. A. SMITH WOODWARD ON THE [May 1904,

noticed that they exhibit a more decided obliquity, with a smaller
median elevation, than the corresponding teeth farther behind.
The transverse measurements (in millimetres) of the teeth of the
several series at the back of the symphysis are as follows :—o, 8 ;
1) 6°51 oe nie gly os Yeu.

The upper dentition of the right side is partly exposed from its
decayed attached face (Pl. XV, fig. 2, 1'-v1'), partly seen from its oral

Ptychodus decurrens, Ay. ; oral aspect of the mandible of a small
variety or young individual, restored natural size; from the

Lower Chalk of Glynde (Sussex ).

aspect on a detached piece of chalk (fig. 3). The median row of
very small teeth is scarcely visible in the fragment just mentioned,
the large teeth of the first paired series being crushed together to
obscure it, but it is shown in back-view (fig. 3a, 0’). Of the first
paired series (1') three teeth are preserved on the right and six on
the left side, all in natural sequence. They are about as large as
the teeth of the same series in the opposing jaw. The two or three
hindermost teeth (fig. 4) correspond with those ordinarily forming

‘By'SNHUMNODAA SNAGOHDALd
‘YUM Fe 'TSp. [PeYS MT A

‘dua sorg wae Fay

eo! &

NAN OeG. Omics a Sal,
UNTRUE ASA 2 eS [Oe r) UATLOP JLB

Vol. 60. ] JAWS OF PTYCHODUS FROM THE CHALK. 135

this series in P. decurrens, but as they are traced forward towards
the end of the symphysis, they become shorter in proportion to their
width and more obliquely distorted, while their median coronal
elevation is smaller (fig. 5). The remaining lateral teeth are more
or less displaced, but they are clearly arranged in six paired series
altogether (fig. 2); and near the back of the symphysis the teeth
have the following transverse measurements (in millimetres) :—
feet 6-3: wea a, £; Iv’, 3°53 v', 33 v1 (2).

The specimen therefore proves that, notwithstanding the powerful
nature of the grinding-dentition of Ptychodus and the straightness
of its transverse rows, the supporting Jaws had not assumed the
peculiarly-effective disposition characteristic of the living Mylio-
batidz, as I formerly supposed. Although it is quite likely that the
angle between the mandibular rami seen in fig. 2 (Pl. XV) is slightly
altered by accidental distortion, the fossil clearly shows that this
cannot have exceeded a right angle. The teeth must thus have
been supported by the elongation of the symphysis, of which there
is very distinct evidence. This arrangement is peculiar, not to the
Myliobatidie, but to the closely-allied Trygonide, which have often
a powerful dentition. In fact, while Ptychodus is most closely
related to the Myliobatidz by its teeth, as pointed out on former
occasions,’ it is now shown to resemble the Trygonide by its jaws.

The probable explanation of the new discovery is that, in the
Cretaceous Period, the great rays of the ‘families’ Myliobatide and
Trygonide had not become fully differentiated. Prof. O. Jeekel* has
already arrived at such a conclusion from general considerations,
and proposed to place all these fishes in one comprehensive family
termed Centrobatide. If this arrangement be adopted, Pty-
chodus represents a primitive sub-family, Ptychodontine, which
still awaits definition from lack of complete specimens; while the
Trygoninee, Myliobatine, and Ceratopterine are equivalent sub-
families which survive at the present day.

EXPLANATION OF PLATE XV.

Ptychodus decurrens, Ag.; remains of jaws and dentition, natural size, with
two teeth (figs. 4 & 5) enlarged twice.—-Lower Chalk (zone of Ho/aster
subglobosus); Glynde, near Lewes, Sussex. Collection of Henry Willett,
Esq. md =mandible; ptg = upper jaw; o-v = teeth of lower jaw;
o'—v1'=teeth of upper jaw.

Fig. 1. Lower aspect, without symphysis.

2. Upper aspect, showing the extent of the decayed symphysis.
. Part of upper dentition, oral aspect; 3a, posterior end-view.
. Posterior tooth of the upper first paired series, left side.

. Anterior tooth of the same series.

Cre Co te

' A. S. Woodward, Quart. Journ. Geol. Soe. vol. xliii (1887) p. 129; also
Proc. Geol. Assoc. vol. x (1888) pp. 294-98, and ‘ Catal. Foss. Fishes Brit. Mus.’
pt. i (1889) pp. 182-52.

* «Die eocanen Selachier vom Monte Bolca’ 1894, pp. 115-38.

eon JAWS OF PTYCHODUS FROM THE CHALK. [May 1904,

Discussion.
J

Prof. Sketey remarked on the great interest of the communication,
as establishing the possibility of the existence of an intermediate:
group between the Sharks and the Rays. The specimen brought)
forward by the Author showed that, while the dentition in Péychodus:
was parallel, the jaws protruded forward in a way never observed:
in typical Rays; and while the teeth of Ptychodus were undoubtedly |
used for crushing, the jaw was prehensile.

Vol. 60. ] IGNEOUS ROCKS OF THE BRISTOL DISTRICT. 137

12. The Ieneous Rocks associated with the Carsonirerous Lim EstoNe
of the Bristot Disrricr. By Prof. Conwy Lrioyp Moréan,
LL.D., F.R.S., F.G.S., and Prof. Sipney Hucu Reynorps, M.A.,
F.G.S. (Read December 16th, 1903.)

[Puates XVI & XVII.]

Conrents.
Page
ee RMNIIGAENIR bok Ooh iano ono ot a Secs os oon SSS a hg hie en dae do ncaa ckivan amare OT
II. The Evidence for the Contemporaneous Origin of the Igneous

re han on) vase Sep At cede dee = ap asieeen «eee oS 159
ItI. The Approximate Horizon of the Igneous Rocks ....................2465 147
IV. The Petrology of the Igneous Rocks ........... Be ret aa dlh slats ag Oe 151

(A) The Lavas.

(B) The Tuffs.
VY. Conclusions ...... BP Meet ne Sedaris 5 aaron vaige se aan eeee sais wineae «Ra ener 155

I, Inrropvucrtioy.

In the * Summary of Progress’ of the Geological Survey for 1598
(pp. 104-11) Sir Archibald Geikie & Mr. Aubrey Straban contri-
buted an admirable section on the Volcanic Group associated with
the Carboniferous Limestone of Northern Somerset. Although in
this summary the evidence for the contemporaneous character of the
igneous rocks is clearly set forth, the subject is of sufficient interest
and importance to justify some further record.

The earliest-published reference to these voleanic rocks, with
which we are acquainted, occurs in a note contributed by the
Rev. D. Williams to the Geological Society on June 10th, 1840."
The note refers to the occurrence of ‘fine porphyritic trap’ in
the Uphill Cutting, near Weston-super-Mare, of the Bristol & Exeter
(now Great Western) Railway-line. In the figure which accom-
panies Williams’s short paper the igneous rock is described as ‘ trap,
apparently substituted for the originally continuous limestone. by
slow fusion and conversion. Dean Buckland appears, however, to
have observed the occurrence of igneous rocks at another locality in
the district as early as 1817, though the first-published record of
the fact occurs in his Presidential Address to the Somersetshire
Archeological & Natural History Society in 1849.° Although no
detailed evidence is given, his brief statement suggests that he had
recognized the volcanic nature of the beds. ‘The vents, he says,
‘that have discharged igneous rocks in the hills of Somerset are
few, and adds that cne of these occurs ‘on the N.W. shoulder of

? Trans. Geol. Soe. ser. 2, vol. vi, pt. ii (1842) p. 561.
> Proc. Somerset. Arch. & Nat. Hist. Soc. vol. i (1851) p. 18.

138 PROFS. LLOYD MORGAN AND REYNOLDS ON THE | May 1904,

Broadfield Down near the upper terminus of Brockley Combe.” Dean
Buckland said that he was not aware that it had been recognized
by any subsequent observer. And this statement still holds true,
unless (as is probable) that, speaking from memory, when he said
‘ Brockley Combe’ he meant the neighbouring Goblin Combe, near
the upper end of which the fragmental deposits of the nature of
coarse tuffs are well seen.

In the geological map of the Bristol Coalfield by William Sanders,
which was begun in 1840, at the instance of Sir Henry Ge la
Beche, and published in 1864, the following exposures ot ‘trap’
are given :—

(1) In the Uphill Cutting, 2 miles south of Weston-super-Mare (Sheet 12).

(2) At Spring Cove, a little to the north-east of the pier, Weston-super-Mare
(Sheet 12).

(3) At Middle Hope, to the west of Woodspring Priory, 3 miles north-east of
Weston-super-Mare (Sheet 8).

(4) In Goblin Combe, 13 miles north-east of Wrington (Sheet 9). Four
exposures are marked, erroneously associated with Old Red Sandstone.

(5) Near Cadbury Camp, 3 miles east-north-east of Clevedon (Sheets 5 and 9).
Two exposures are marked.

With the exception of the last, ali these are indicated in the
Geological-Survey maps (1865). Two exposures are marked in
Goblin Combe, and the supposed association with Old Red Sandstone
is corrected.

In 1868 David Mackintosh ' noted the occurrence of the igneous
rock at Spring Cove, describing it as a conformable mass of trap.
He says that it

‘has, I believe, hitherto been regarded as intrusive. But a comprehensive
inspection will, I think, show that it isa bed which, in a fused state, must have
flowed over the limestone beneath, before the limestone above was deposited.’

In the same footnote Mackintosh states that Mr. Ravis, of Bristol,
had informed him that a similar bed of trap occurred in the lime-
stone near Sandpoint. This had, however, been previously recorded
in Sanders’s map. In the same year Ravis* described the Middle
Hope trap, apparently regarding it as intrusive, but stating that it
was probably injected during the deposition, although before the
eievation of the limestone.

Im Mr. Horace B. Woodward’s Survey Memoir on ‘ The Geology
of East Somerset,’ published in 1876, a section, by Sanders, of the
cutting at Uphill is given (pl. 11, facing p. 24),in which the igneous
rock is entered as ‘trap dyke.’ A note is contributed by W. T.
Aveline on the ‘large igneous dyke’ at Middle Hope ‘running

* Quart. Journ. Geol. Soc. vol, xxiv (1868) p. 282.
_~ ‘Supplementary Notes on some of the late Movements on the Somersetshire
Coast’ Proc. Bristol Nat. Soc. ser. 1, vol. iii (1868) p. 89.

Vol. 60. | IGNEVUS ROCKS OF THE BRISTOL DISTRICT. 139

- with the beds of limestone and shale and altering them above and
below’ (p. 22), and a section is given, drawn by Aveline. The
volcanic breccia at Cross Combe (Goblin Combe) is mentioned (loc.
cit.), but the occurrence of ‘trap’ is not recorded. In an Appendix
(p. 210) Mr. Rutley describes the rock from Woodspring Hill
(Middle Hope) as a much-altered basalt, to which a specimen from
Cleve Combe (Goblin Combe) is closely similar; and that from
Wrington Warren, which is not identified as part of the Goblin-
Combe exposures, as a volcanic breccia. ‘It is just possible,’ says
Mr. Rutley, ‘ that this breccia may be derived from the margin of a
dyke’ (p. 210). He had evidently not seen the rock in the field.
Figures are given of some of these rocks.

Prof. Sollas writing,’ in 1880, an account of the Geology of the
Bristol District, in connection with an excursion of the Geologists’
Association, makes passing allusion to

‘an episode of igneous activity, which has left its traces in the thick beds of
voleanic ash associated with once vesicular but now amygdaloidal basaltic lava,
to be seen interbedded in the limestone along the coast-section from Weston-
super-Mare to Swallow Cliff.

Whether this refers to Spring Cove or Middle Hope is not clear ; but
probably the latter locality was intended.

In the ‘Annual Report’ of the Geological Survey for 1896
brief allusion was made to the records of contemporaneous volcanic
activity at Middle Hope (pp. 61-62). One of us made brief reference
to them in the British Association Handbook published in 1898
(Bristol Meeting), and also drew attention to beds of volcanic ash
on Worle Hill to the east of the camp (above Kewstoke Steps).
Finally, in the ‘Summary of Progress’ of the Geological Survey
for 1898, Sir Archibald Geikie & Mr. Strahan gave the fuller
account, already mentioned, of the Northern Somerset volcanic
group.

Il. Tae Evipencre FoR tHE CONTEMPORANEOUS ORIGIN OF THE
IGneovus Rocks.

(1) At Middle Hope (Woodspring).

The evidence for the contemporaneous origin of the igneous rocks
in this locality has been so well set forth by Sir Archibald Geikie
& Mr. Strahan that little need here be added. There are four
exposures, three of which are described in the ‘Summary of
Progress * of the Geological Survey for 1898. The fourth lies
farther to the east, where the coast-line trends sharply southward

* Proc. Geol. Assoc. vol. vi (1880) p. 378.

Hip vs

from St. Tho-
mass Head.
The repetition
of the expo-
sures is due to
several small
faults running
at right angles
to the coast-
line.

(a) In the
first or western-
most exposure,
bedded cri-
noidal lime-
stone, with
abundant Za-
phrentis, 1s suc-
ceeded by an
alternation of
limestone and
red or green
tufts, in which
organic remains
are frequently
embedded, and
well - marked
lapilli are abun-
dant. Then
comes the ‘ pil-
lowy, much -
altered, amyg-
daloidal basalt,
which has in
parts degene-
rated into a
brown sandy -
looking mate-
rial, wherein
little can be
made out ex-
cept the amyg-
dules. This is
followed by
further alter-
nations of
limestone and
tuff passing up
into the mas-
sive limestone,

——
« —— .
p BETA

Beds

t

{ren
roup

=
5 exp.c

Zaphr
ey

¢

~

— 2

‘

Volcanic Bed

a
&
%
a
¥
eal
_~ ;
a
Ss
aa
O;.
To)
rey:

Oolitic Beds © N

_ ae

éntis Beds

mile.
age
Group A

phr

sexp.a §
Bo

ae

3

c
€

Geological Map of
Middle Hope or Woodspring:
scale;- 3 inches =!
Za
aie
Volcanic Beds”
Toup

Vol, 60. | IGNEOUS ROCKS OF THE BRISTOL DISTRICT. ~ Tat

throughout the lower 7 or 8 feet of which big lapilli, reaching
a length of 2 inches, are fairly plentiful. (See figs. 2 & 3,
pp. 142-43.)

(4) In the second exposure, three-quarters of a mile farther east,
alternations of reddish-brown or green tuff, with lenticular bands
of limestone, occur. But there is here no basalt, and the volcanic
series is thinner." (See fig. +, p. 144.)

(c) The third exposure, some 200 yards still farther east, shows
brown tuffs and nodular or lenticular limestones in alternating layers.
The volcanic series is still thinner.

(7) In the fourth, and easternmost, occurrence of the tufts,
hitherto unrecorded, and lying two-thirds of a mile north-east of that
last named, they are reduced to 6 or 7 feet in thickness. But in
the lower part of the section there is no rock-exposure. Here,
however, a coarse fragmental deposit, 2 feet thick, with well-
marked lapilli, is one of the most characteristically-volcanic beds
of the whole series. The gradual attenuation of the volcanic
ejectamenta to the eastward and the occurrence of lava only in
the westernmost exposure, support the conclusion arrived at in the
‘Summary of Progress’ that the centre of volcanic activity pro-
bably lay yet farther west.

? The details of this section are as follows :—
Thickness in feet inches.
20. Thick crinoidal limestone to the top of the cliff.
19. Weathered grit, with red shale visible at the

PAREEBNGGOITION © «no 1a5e, Sok ede ca eco wine d oe via 10 0
MP PRIORETIG Wie coe Se Eee ene Sec nak accdee 12 0
rae, Na ween aatiel rer eek a cee, coca de oe cew cnn 5 tot 0
16. Sandstone, with vertical cylindrical bodies ...... 2 6
Beene AAW wsccc5 2.0L cha La pene ae ps 0
14. Lenticular limestone-band ..................ceeeeeees 0 38to6

13. Coarse ash, with highly-caleareous bands in the
lower part, numerous large fragments of lime-
stone and some of grit in the upper part......

eNO Hes ABEREM o0b Sete oot. sro dase ee anak a. ax¥e Seomes

11. Brown ash, very much decomposed and veined...

Rai RATAGMITIG oa 6e sas «ov ones sat emmacar ascaveces bee sisnans

9. Ash as above (11), the upper part containing

jen
Om Coe

numerous lamellibranchs (Edmondia) ......... pli 0
8. Reddish crinoidal limestone .....................66- 1 0)
Pee a OT Sere nD pe Lae ek ee 2 0
Gy erotinecagus limestone) 4.26.2. <s00~ ones. vay niesn ene i! 0
PIE MONE Foot ait ae econ oie veya cGied acu ve- dun 3 6
4. Compact, somewhat argillaceous limestone ...... 0 6
See EMANES fecha dtie a Sued nix cs echt veeccatees 11 0
2. Limestone, in bands 3to6 inches thick, with part-

ings of red shale and, at about a foot from

the top, one of green ashy material ; the upper-

most band of limestone is very argillaceous... 7 0

1. Massive limestone, with much chert, to the base
OF THO RECEION§ F260 02s Seat eiabee iva about 90 6

‘tdsojoyd *y cH ‘sg

‘husdspooy, «0 adopy aypprpyy 40 ‘a.voys ay) Wo sarsas ouupajoa ays Jo aunsodwa psow.tajs24{—"G “SUT

yed zamoy ayy ur pide]
aS3Ie] YIM VU0}sSoUNT] QAISSPJAT yse aqeiiea Surfs] 1900
hay suojsaun] AYyse 29 ysy STISSOJ JO [[Ny 2U0jsauNTT

!

yeseq jeprorepsAuy

CI¢T-6er "dd vay) -aunsodaa anogn ay) fo spwpp ayy bunnnysnppr YHYS—e “BIT

144 J

"sal poq "9U0}SOUT1]

[volapurpAod [BorydoAa ‘OYTOTBO JIM POUOA jo purq
(IM ‘euojspurg yonur ‘Yse oury WLU T, "I]sB OSAVO-
eT Wa eS Lae So ee ee aS on Hh

| ‘yoo & yuOqV = UWOTJoos JO TJS |

(rrp ‘daag) ‘aansodxa puovas ‘hursdspoog, jv sarcas ovunojoa ayy Jo pwnd wodda—"p “Sty

Vol. 60. | IGNEOUS ROCKS OF THE BRISTOL DISTRICT, 145

(2) At Spring Cove, Weston-super-Mare.

In the limestone above the altered, and in parts variolitic, olivine-
basalt, Sir Archibald Geikie & Mr. Strahan found fine volcanic dust
for about 3 feet above the surface of the lava. We have, however,
a rock-slice taken from a height of 8 feet above the basalt which is
full of small lapilli. On the other hand, although there are several
ashy-looking lenticular bands below the lava, our four rock-slices
taken from these beds at several different levels show no conclusive
evidence of the occurrence of distinct oe We are therefore
unable fully to endorse the statement that ‘ through some 30 or
40 feet of its mass’ the limestone ‘ below the basalt is full of
disseminated volcanic particles.’ A soft, red, ashy-looking bed,
close to the path leading down into the cove, contains abundant
large corals belonging to the genus Campophyllum.

(3) Above Kewstoke, Milton Hill.

In the ‘Summary of Progress’ for 1898 (p. 106) it is stated that

‘fragments of the amygdaloid were found by Mr. Spencer Perceval at the
Tollgate, which show that this rock extends inland for a mile and a half.
But ‘immediately to the east, over the bare limestone-surface above Kewstoke
or Milton Hill and the ground towards Worle, Mr. Strahan could find no
trace of it.’

Mr. Spencer George Perceval writes to one of us:

‘Which Tollgate is meant Ido not know. In the fields immediately outside
the wood on Worle Hill at the eastern end, north of the Lodge, I found in
1890 that an overflow of trap occurred, not visible at the surface, but at
a slight depth underneath. I got specimens with the limestone and trap in
contact. I certainly should not term the trap an amygdaloid,’

In a further communication, Mr. Perceval has courteously supplied
extracts from his notes made at the time. It is quite clear from
these notes that he then discovered an extensive run of the ‘ trap’
on Milton Hill. In gardens west of the road running from Milton
to Kewstoke he instituted a series of diggings, which showed that
the ‘ trap-bed’ was there in situ. It was also found, by digging, in
the garden of the lodge just outside the wood, on the western end
of Worle Hill. ‘Trap’ was also found in places within the wood
along the same strike. These observations leave no doubt of the
extension of the lava in this direction. One of us became acquainted
(without any knowledge of Mr. Perceval’s previous discovery)
with the ‘trap ’-fragments, some of them very vesicular, which are
scattered over the gardens in the north-western angle of the cross-
tracks, one leading along the crest of the hill, the other crossing

* «Summary of Progress of the Geological Survey for 1898’ p. 105,
Q. J.G.8. No. 238. L

146 PROFS. LLOYD MORGAN AND REYNOLDS ON THE [ May 1904,

from Milton to Kewstoke. A cottager, who was digging in the
garden, pointed out a strip running across the field where, he said,
all the stones turned up in digging were of this kind. Another
man in 1902 made a similar statement. From this field we have
ourselves collected many fragments of lava, and a few of a brecciated
rock. Moreover, in 1894, at a spot 150 yards down the track
leading to Kewstoke, one of us observed a small excavation in which
unmistakable voleanic ash was seen in situ. This exposure was
shown at the time to Mr. A. C. Pass, then Secretary of the
xeological Section of the Bristol Naturalists’ Society, who was
satisfied as to the nature of the rock. Unfortunately, when we
visited the spot, in 1902, we found that the excavation had
been walled in, stone-lined, and converted into a small pond. A
note made in 1894 is here transcribed :—

‘Voleanic ash in field [near track] leading down to Kewstoke Steps. Soft,
friable, reddish beds, seemingly greener when not exposed (that is, when dug into
with the hammer). Numerous vesicular lapilli up to half an inch in diameter.’

In 1903, round a small pond just above the upper extremity of
Kewstoke Steps, we found abundant fragments of lava (? lapilli) in
a red, earthy, surface-material. Farther eastward we have found no
trace of lavas or ashes.

(4) At Uphill.

The relations of the amygdaloidal basalt or dolerite to the lime-
stone are not well seen here. The ground is much faulted. There
is, in our opinion, nothing to enable us to decide whether the igneous
rock is a sill or a contemporaneous lava-flow. Nor have we been
able to find in the limestones, either above or below, any traces of
ash or lapilli. As will be seen, however, under the next heading
(p. 150), the igneous rock occupies exactly the same position in
the stratigraphical series as that which the volcanic rocks occupy
in other localities.

(5) In Goblin Combe.

The Carboniferous Limestone of this upland area, lying north of
Wrington, forms an anticline or dome. The volcanic rocks occur
in two patches, the more westerly being about a third of a mile
south of Warren House, the more easterly about half a mile south-
east of this house. Sir Archibald Geikie & Mr. Strahan suggest that
the two exposures form parts of the same volcanic series, repeated
on the two sides of the anticline. In this, as we shall see, they are
probably correct.

(a) In the more westerly exposure a much-weathered and highly-
amygdaloidal olivine-basalt is seen in situ, although it seems to
have escaped the notice of Mr. Strahan, who observed only scattered

Vol. 60. ] IGNEOUS ROCKS OF THE BRISTOL DISTRICT. 147

blocks. The fragmental beds are here found above the lava, but
there is an interval in which there is no exposure. They consist
of a reddish ashy limestone and a thinly-bedded, greenish, ashy and
gritty limestone, coarser below and finer above, in which oolitic
granules occur plentifully.

(6) The more easterly exposure affords perhaps the most
characteristic and convincing section of ashy beds in the district.
The lenticular bands of coarse greenish tuff, the limestone-inter-
calations, the close admixture of lanpuilli, limestone-fragments, and
oolitic grains, the whole appearance of the 15 or 14 feet of rock
exposed in a vertical mural face are stamped with the hall-mark of
submarine volcanic action. The beds seem to cross the track
about 200 yards to the north-west, as it ascends the hill near an
orchard. No lava occurs in situ here; but a remarkably-fresh
olivine-dolerite is abundantly found in small blocks (among which
are some of breccia) scattered over the field to the west of the
main exposure. It may therefore be inferred, since the dip is
easterly, that the lava closely underlies the breccias and tuffs, as
in the other Goblin-Combe exposure.

(6) Near Cadbury Camp.

Beyond the occurrence of fragments of ‘trap’ thrown out from
rabbit-burrows in Wood Lane, at the angle between Round Wood
and St. John’s Wood, we have found no indication of the exposures
marked in Sanders’s map. There is nothing to show whether or
not the trap is contemporaneous.

Til. Toe Approxorare Horizon oF tHE Ieneous Rocks.

In the ‘Summary of Progress of the Geological Survey’ no attempt
is made to assign to the volcanic rocks any definite place in the
stratified series which constitutes the Carboniferous Limestone.
In 1898 one of us stated, in the British Association Handbook
(Bristol Meeting), that the Middle Hope beds were of an age
slightly anterior to that of the band of oolitic rock which occurs
_ at the foot of the Gully in the well-known Clifton section ; and,

from observations made in 1894-95, he had tentatively assigned
to the Spring-Cove lava a position about 150 feet below this oolitic
band. In endeavouring to work out the position of the volcanic
series with greater precision we have had the advantage of much
paleontological assistance from Mr. Arthur Vaughan, B.Sc., F.G.S.,
who is engaged on the zoning of the Carboniferous Limestone
of the district under consideration. We tender him our hearty
thanks for his ungrudging assistance. He has supplied for our
guidance, and allows us to quote, the following table, wherein certain
broadly-marked horizons which bear on the subject in hand are
indicated :-—

About 100 feet.

About 135 fect.

148 PROFS. LLOYD MORGAN AND REYNOLDS ON THE [{ May 1904,

Position of Beds re-
ferred to the section

novth of the Meo Sequence. Paleontological characteristics.
Bristol.

Lower part of Great ) ( Marked by the entrance of Lithostrotion,
Quarry and underlying > HiGHER Beps. < Producti belonging to the giganteus-group,
Dolomitic Beds. Y Land Athyrids of the ambigua-group (Seminula).

Oolitic beds in the >

quarry at the foot of |
che Gully. | ( Marked by the great abundance of Orthotetes
R —-\ Crone | (Streptorhynchus) crenistria, Chonetes papi-
Pele ieten tke Bee lionacea, and Ch. aff. comoides. In these beds
eh 2 Spirifer att. Jaminosus reaches its maximum.
Gully & the Black- ee
Rock Quarry. a
Upper third of —) ( Marked by the abundance of a Zaphrentid
ra Group B, ~of the cylindrica -type (Campophyllum =
the Black Boek J) resting immediately | Zaphrentis cylindrica of Edw. & Haime).}
; upon or forming the
2 Eos { Containing cornute Zaphrentids in great
Quarry. Group A. < = Pp ©
5 ¢ abundance.
( Marked by the rarity of Zaphrentids and by
He gradual increase doa of Spirifers of
Lower and middle ) the bisulcatus - group and of the glaber-type
thirds of the Black- > Lower Beps. < (Martinia);: Athyrids of the Royssii-type
Rock Quarry. J | (Cleiothyris); Orthids of the Michelini- and

| resupinata-types, Leptena analoga, and Pro-
| ductus of the punctatus- and Martini-types.

As will be seen by the sequel, the voleanic group les approximately
on the horizon of Group B, a position which accords with that
assigned to the Middle-Hope and Spring-Cove lava by one of us—
that is to say, somewhat anterior in time to the Gully oolite.

1) At Middle Hope, Woodspring.
) Pp pring

The beds below the volcanic series, which are well displayed on
the coast-line, unquestionably belong to Group A, and contain
cornute Zaphrentids in great abundance. Mr. Vaughan has identi- -
fied Zaphrentis Phillipsi, M.-Edw., Z. aff. Enniskillen, M.-Kdw.,
Z. aff. Griffitht, M.-Edw., and Z. sp, nov. ; Michelinia, sp., Leptena
andloga, Phill., Orthis Michelina, L’Eveillé, Productus punctatus var.
elegans, M‘Coy. The lower ashy beds are probably in Group B. On
the southern coast of the peninsula that terminates in Swallow Cliff
the Chonetes and Streptorhynchus characteristic of Group C occur ;
and similar beds may be found 150 feet above the more easterly
exposure of the tuffs.

* [Mr. A. Vaughan has more recently, in Proc. Bristol Nat. Soc. vol. x, pt. ii,
p. 102, revived M‘Coy’s genus Caninia, to cover the Zaphrentid-group which
is typified by Campophyllum cylindricum.—March 14th, 1904.]

Vol. 60. } IGNEOUS ROCKS OF THE BRISTOL DISTRICT. 149

(2) At Spring Cove, Weston-super-Mare.

In a red ashy bed, which marks the earliest stage of the volcanic
phase, large examples of Campophyllum cylindricum, Scouler,
indicative of the upper part of Group B are conspicuous. In the
lowest bed on the foreshore cornute Zaphrentids occur
‘together with a coral which exhibits characters transitional between those of
the Cyathophyllum- (Strephodes) and Campophyllum-types.’

Again, about 100 feet above the lava, in a mural face below the
western end of Worlebury Camp, occur in abundance the cha-
racteristic fossils of Group C. Commenting on the fossils obtained
thence, Mr. Vaughan says

‘ Streptorhynchus crenistria, Leptena analoga, Productus Martini, Pr. elegans,
and Spirifer cuspidatus leave no possible doubt of the horizon.’

The Spring-Cove volcanics, therefore, occupy approximately the
same position as those at Middle Hope. It may be mentioned,
however, that on the road through Kewstoke Woods, in a position
which seems to be well below the volcanic series, occur fossils
which unquestionably indicate a much higher level—that marked
‘Higher Beds’ in the foregoing table (p. 148). There is some
faulting which brings these beds down to their present position.

(3) Above Kewstoke, Milton Hii.

Here, again, faulting has complicated the problem. At Kewstoke
Steps the limestones are well displayed. There can be no question
that they belong to the higher beds. Producti belonging to the
giganteus-group, Athyrids of the ambigua-type, and abundant
Lithostrotion beautifully weathered-out, are conclusive. But shortly
below these rocks—assuming that the stratigraphical sequence is
unbroken—-come the volcanic ash (noted in 1894) and the scattered
fragments of lava and breccia. On the southern side of Milton
Hill, however, there are two quarries, the beds in which should,
taking dips and distances into consideration, overlie the volcanic
series. In one of these, a disused quarry, lying to the right of the
road from Milton to Kewstoke, just below the crest of the hill
on its southern side, the fossils indicate that the beds lie on the
same level as those of the mural escarpment above Spring Cove.
Chonetes, Streptorhynchus, and Spirifer laminosus, M‘Coy, occur,
and a typical Productus Martini, Sow., as also above Spring Cove.
The other quarry, which lies farther west, and is now being exten-
sively worked, does not afford conclusive evidence. But at the top
occurs a coral of the same transitional type as that noted at Spring
Cove, which, in Mr. Vaughan’s opinion, cannot occur below the
very top of the Black-Rock Quarry. In the lower beds of the quarry
occur
‘ Streptorhynchus (large resupinate var.), Spirifer cuspidatus, Martin, a small
Athyris of the seminula-group, and a rather characteristic Athyris of a transverse
Royssii type.’

150 PROFS, LLOYD MORGAN AND REYNOLDS ON THE _{ May 1904,

No cornute Zaphrentids were found, and the probability is that the
beds belong to Group B. On the whole, therefore, evidence again
points to the conclusion that the volcanic rocks here too occupy
approximately the same position as those at Spring Cove and
Middle Hope. That there is a strong fault between the Kewstoke
rocks and those in the quarries on Milton Hill, so as to thrust up
the former beds to their present position, is certain. And this
is in line with the facts already noted under the head of ‘ Spring
Cove.’

(4) At Uphill.

We have not been successful in obtaining many fossils from the
limestones above and below the ‘trap’ here. We submitted,
however, a number of fragments to the etching effect of weak acid,
partly with a view to the disclosure of any lapilli which might be,
but were not, present. Mr. Vaughan kindly examined some speci-
mens from below the ‘trap.’ He says :—

‘IT am convinced that the Uphill specimens denote beds on the level of the
upper portion of the Black-Rock Quarry, and therefore on exactly the level of
the Woodspring specimens. Zaphrentis Phillipsi, M.-Edw., a bisulcate Spirifer,
and small cylindrical crinoid-stems are the only fossils to be seen. Of these,
Z. Phillipsi ranges from the middle of Press’s Quarry (just below the Black
Rock) to the Campophyllum-beds (B) at the top of the Black Rock; but its
main development is at the top of the Black Rock (never above). Bisulcate
Spirifers in isolated examples (as here) point to the same horizon (or very much
lower, which is rendered impossible by the associated Zaphrentis).’

As before noted, there is here no distinct evidence of the con-
temporaneous origin of the ‘trap.’ But the paleontological evidence
that it occurs at the same horizon as the Middle- Hope and Spring-
Cove lava, makes its volcanic nature, as a submarine outflow at any
rate, highly probable.

(5) In Goblin Combe.

(a) Easterly exposure.—Fossils taken from a level about
100 feet above the mural exposure of breccia and tuffy limestones
contain Chonetes papilionacea, Phill., Streptorhynchus crenstria,
Phill., Athyris Royssi, L’Eveillé, and Spirifer cristatus (var. octo-
plicatus, Sow.). These, in Mr. Vaughan’s opinion, mark the lower
part of Group C, and are therefore in exactly the same relative
position as at Middle Hope and at Spring Cove. There is no ex-
posure immediately beneath the volcanic rocks; and the level of the
rocks, just west of the orchard, cannot be readily calculated, as the
dips are changing near the summit of the anticlinal arch. These
beds, which may lie 100 feet or so below the tuffs, contain
Zaphrentis Phillipsi, M.-Edw., Z. Enniskillent, M.-Edw., Z. sp. nov.
(‘the very commonest,’ says Mr. Vaughan, ‘of the Zaphrentids of
Clevedon, also found in the Avon section, Tytherington, etc., but not
yet figured or described’); also a specimen of Spirifer aff. clathratus,
M‘Coy (small and presumably uncommon). The highest bed seen
contains Campophyllum cylindricum, Scouler. These fossils point to

Vol. 60.] IGNEOUS ROCKS OF THE BRISTOL DISTRICT. 151

' Group A and the lowest part of Group B. Here, again, therefore,
the horizon of the volcanic rocks may be assigned to the same
position as in other localities.

(6) Westerly exposure.—the only definite piece of evidence
of the position of these beds is the occurrence of a fossiliferous band,
at a level of about 120 feet above the exposure of the lava. It hes
some 200 yards south of Warren House, on the eage of the plateau
where it overlooks Goblin Combe. The fossils include Chonetes aff.
comoides, Sow., Streptorhynchus crenistria, and a bisulcate Spirifer :
all of which points conclusively to Group C. We have not, however,
succeeded in finding evidence of the underlying Zaphrentis-beds.
But little limestone is visible below the lava, which is nearly the
lowest bed exposed by denudation in the excavation of the Combe.
Such evidence as there is in this locality points again to the same
horizon as elsewhere in the district.

(6) Near Cadbury Camp.

Since the volcanic rocks are not here exposed 77 situ, we do not
attempt to discuss the question of their horizon. They seem, how-
ever, to lie in about the same position. Mr. Vaughan tells us that
in cuttings by the side of the track which follows the telegraph-
posts along the top of the ridge, that is to say, at a stratigraphical
level somewhat below the probable outcrop of the ‘trap,’ the
Zaphrentis-heds are strongly in evidence, and he has collected most
of the typical fossils of Group A.

It will be seen that in all the localities where the position can
be approximately determined, the evidence is sufficient to justify the
conclusions (1) that there is one igneous group marking a single
volcanic episode, and (2) that this occurred at a period which is
marked by the occurrence of the marine fauna indicated by Group B
in the table supplied by Mr. Vaughan (p. 148), to whom we desire
again to offer our thanks for his assistance.

LV. Tuer Perrotocy oF THE IenzEovs Rocks.

But little has been written on this subject. In Appendix I to the
Survey memoir on the Geology of the East Somerset & Bristol Coal-
Fields are descriptions by Mr. Rutley, of the Uphill and Woodspring
traps, and one of the ashes from Wrington Warren. In Sir Archibald
Geikies & Mr. Strahan’s account, the petrology is incidentally
dealt with, and a description of the Spring-Cove lava by Mr. Teall
is given. These will be again referred to in due course.

(A) The Lavas. (Pl. XVII, figs. 1-3.)

The freshest and most interesting lavas are those of Goblin Combe
and Spring Cove, and it will perhaps be best to describe these some-
what fully.

152 PROFS. LLOYD MORGAN AND REYNOLDS ON THE May 190
¥ 1904,

(1) Description of the Lavas of Goblin Combe.

The rock seen in situ at the more westerly exposure is a highly
amygdaloidal olivine-basalt. In a hand-specimen it shows pseudo-
morphs after olivine, and vesicles which may be more than half an
inch in diameter, and are sometimes empty, sometimes filled with
calcite and a green chloritic mineral. Microscopically, the most
prominent mineral is altered plagioclase, in laths having an average
length of about 0:4 millimetre and a diameter of 0°04 mm. The
spaces between the laths are partly filled up by a brown, nearly-
isotropic substance, but chiefly by green patches of serpentinized
pyroxene and by calcite. Dark rods, once magnetite, but now replaced
by the peroxide, are very plentifully scattered. The phenocrysts,
which are large and prominent, are entirely represented by patches of
a carbonate, probably calcite, and from the perfect preservation of the
form of some of these it is clear that they represent olivine-crystals.

The olivine-dolerite or basalt which occurs in blocks on the
surface of the ground near the more easterly of the Goblin-Combe
exposures is the handsomest of all the igneous rocks of the district.
It consists of fresh plagioclase-laths with a maximum length of about
0-5 millimetre; fresh brown augite, occurring in grains filling up
the interstices between the laths, and also forming phenocrysts and
polysynthetic crystals which reach a length of slightly over a milli-
metre; magnetite in long needles; and olivine, now completely
converted into green serpentine, but showing the crystalline form
excellently. (See Pl. XVII, fig. 1.)

(2) Description of the Lava of Spring or Birnbeck
Cove, Weston-super-Mare.

The lava here is a rather interesting basalt, and resembles all the
other rocks of the section in being stained a deep red. No pheno-
crysts are visible in a hand-specimen, but there are, as a rule,
numerous amygdules of calcite which reach a maximum diameter
of 3 millimetres. Hand-specimens, too, taken from certain parts of
the flow, show numerous other circular red bodies which prove,
when examined microscopically, to be varioles. The groundmass is
abundant, and is seen in section to show numerous felspar-needles ;
apart from these, it is practically isotropic, and must have been
originally, to a large extent, glassy. It is, however, much obscured
by the abundant red oxide of iron. The varioles above referred to
reach a large diameter (3 millimetres), and are very sharply defined.
They are, however, much altered, and are obscured by the iron-oxide
which is sometimes uniformly distributed through them, sometimes
forms a peculiar network traversing them, and is occasionally collected
along lines which radiate inward trom the circumference for a short
distance with extreme regularity. (See Pl. XVII, fig. 3.)

The chief phenocrysts present are a few felspars in a greatly-
altered state. The large amygdules are filled with well-cleaved

Vol. 60. | IGNEOUS ROCKS OF THE BRISTOL DISTRICT. 153

ealcite, with sometimes in addition a brown, possibly chloritic,

mineral occurring in collections of irregular spherulites. Mr. Teall’s

description of a lava from Spring Cove, quoted by Sir Archibald Geikie
P pom »q z

& Mr. Strahan, is as follows :—

‘The lava from Spring Cove, Weston-super-Mare [E. 3212 (23)], is a fine-
grained, chocolate-coloured rock, composed of ps:udomorphs after olivine, and
probably augite, in a groundmass showing microlitic structure. The pheno-
erysts are represented by pseudomorphs in carbonate. The microlitic felspars
of the groundmass are colourless, but they no longer show their characteristic
optical properties. The groundmass is deeply stained with ferric oxide.
Although all the minerals have been destroyed, the structure has been perfectly
preserved, and there can be no doubt whatever that the original rock was an
olivine-basalt.’

Most of our sections from Spring Cove did not show the carbonate-
pseudomorphs above referred to, which are so clearly seen in the
Goblin-Combe rocks, but they were met with in one section.

(3) Summary of the Characters of the Lavas.

The rocks vary a good deal in coarseness, the coarsest-grained
being those from Uphill and from near Cadbury Camp, of the con-
temporaneous character of which there is no direct evidence. The
Goblin-Combe rocks come next in degree of coarseness, while the
finest-grained are those from Spring Cove and Milton Hill.

All the rocks are clearly basaltic in character, and consist
essentially of plagioclase-needles, laths, or phenocrysts, with pyro-
xene and iron-ore, and, as a rule, olivine. The pyroxene is
generally undoubtedly augite, but sometimes, as in the Uphill
rocks, the unaltered mineral may have been enstatite. The freshest
augite is seen in the rock from the eastern end of Goblin Combe,
where it occurs both in small grains and large plates. Plates of
fairly-fresh augite are seen in the Cadbury-Camp and one of the
Milton-Hill rocks; and serpentinized pyroxene, probably augite, is
abundant in the rock from the western Goblin-Combe exposure.

Olivine is never preserved in an unaltered state in these rocks,
though in most cases the original form of the crystals is very well
seen (Goblin Combe—eastern end, Milton Hill, Woodspring).
Sometimes the olivine is completely converted into bright green
serpentine (Goblin Combe—eastern end), sometimes a very large
amount of ferric oxide is associated with the serpentine (near
Cadbury Camp), sometimes the olivine is replaced by pseudomorphs
in carbonate, probably calcite, with which dense masses of ferric
oxide are associated (Milton Hill), sometimes it is apparently
simply replaced by pseudomorphs in carbonate (Goblin Combe—
western exposure, and some specimens of the Spring-Cove rock).

The occurrence of long needles of peroxidized magnetite is a
characteristic feature of the Goblin-Combe rocks.

The variolitic character of much of the Spring-Cove lava is an
interesting feature.

* «Summary of Progress of the Geological Survey for 1898’ p. 106.

lot PROFS. LLOYD MORGAN AND REYNOLDS ON THE | May 1904,

Some of the rocks are highly-amygdaloidal (Woodspring, Spring
Cove, Goblin Combe—western exposure, Milton Hill, and Uphill in
part). Others are not (Uphill in part, near Cadbury Camp, Milton
Hill in part, Goblin Combe—eastern exposure).

(B) Whe Tuffs.. (PL XVI, fies: Aq6;)

(1) Description of the Tuffs from Middle Hope,
W oodspring.

The prevalent type of tuff in all four exposures is a rather soft,
dull-green, much-decomposed, and earthy-looking rock, with patches
and veins of calcite and many small green Japilli, which in the
sections examined do not, as a rule, reach a greater length than
2 millimetres.

In section the lapilli are seen to consist entirely of a highly-
amygdaloidal rock, with a groundmass which is almost completely
isotropic, and must have originally formed a basic glass, now altered
into green palagonitic material. The amygdules are generally
composed of a chloritic mineral, sometimes of calcite. The matrix
in which the lapilli are embedded usually consists of well-cleaved
caleite, through which age scattered numerous minute ashy frag-
ments similar to the larger lapilli. In addition to these there occur
at certain levels, especially in the ashy limestone above the trap
at the westernmost exposure, large lapilli, frequently reaching a
length of an inch or more, of a quite different type from those
deseribed above. ‘The groundmass of these lapilli, which is ‘much
irou-stained, contains numerous felspar-needles, but apart from
them is isotropic, and shows no sign of palagonitic modification.
The vesicles are very abundant, and in one slide are filled with
well-cleaved calcite, precisely similar to that forming the main
mass of the surrounding limestone in which they are embedded.
In a second slice the only difference is that the calcite filling the
vesicles is, as a rule, granular and not well cleaved.

(2) Description of the Tuffs from Goblin Combe.

Most of the rocks are, in the main, limestones of a non-oolitic
character, but they contain a variable proportion of oolitic grains
and many quartz-grains, with ashy fragments as well. The pro-
portion of ashy fragments is far greater in some of the rocks from
the eastern exposure than in any of those from the western, but
nearly all are best described as ashy and gritty oolitic lime-
stones. Sections taken from the lowest bed in the more westerly
exposure show that angular quartz-grains are far more plentiful
than either lapilli or oolitic grains. The latter reach a diameter of
4 millimetres. Some of the lapilli are identical with the basalt,
which, as already mentioned, probably underlies the ashy limestones;
they contain the same patches of yellow chlorite or serpentine, and

Vol. 60. | IGNEOUS ROCKS OF THE BRISTOIL DISTRICT. 155

rods of peroxidized magnetite. The red calcareous ash, of the more
easterly section, is the most conspicuous of all the igneous rocks of
Goblin Combe. It varies much in coarseness and in the proportion
of oolitic grains present. Angular grains of quartz are always
plentiful. The lapilli are of two chief varieties: (1) a highly-
vesicular, glassy rock, which sometimes shows green palagonitic
alteration, sometimes is so loaded with ferric oxide that nothing
can be seen except the vesicles; (2) a basalt with felspar-laths,
patches of serpentine or chlorite, and peroxidized magnetite-rods —
resembling, in fact, the lava of the western end of the Combe.

(3) Summary of the Characters of the Tuffs.

They are all highly calcareous, and most are best described as
ashy limestones. The proportion of lapilli is very variable. In
some rocks, such as those from the western Goblin-Combe exposure
and some of those from the eastern, lapilli form less, perhaps, than
a hundredth part of the material. In others, such as some of those
from Woodspring and from the eastern Goblin-Combe exposure,
they form more than one-third. While, in some districts (as is well
known) many of the lava-fragments in the tuffs are of a quite
different type from the lavas which flowed on the surface, that is
not the case with regard to this district, as all the lapilli are basaltic
in character, like the lavas. At Spring Cove and the western
exposure of Goblin Combe the lapilli consist of the same type of
basalt as the associated lava. At Woodspring they are, as a rule,
of a green, highly-vesicular rock, like a basaltic pumice. In the ash
from the eastern end of Goblin Combe both types of lapillus are
represented. Attention has already been drawn to the abundant
quartz-grains of the Goblin-Combe rocks and to their frequently-
oolitic character.

V. ConcLusions.

The observations described in this paper support the conclusions
reached by those previous writers who have indicated the existence
of a voleanic episode in Lower Carboniferous times within the
Bristol district. They render it probable that the ‘trap’ of Uphill
and near Cadbury Camp is a product of contemporaneous volcanic
action. They have somewhat extended the number of recorded
localities in which lava or tuff is exposed. They establish the fact
that in all cases the lavas are basaltic in type, and that the lapilli
found .in the adjacent beds are of the same basaltic character.
And they show that the volcanic episode in all cases occurred
during the deposition of the upper part of the Zaphrentis-beds,
and before the strata characterized by Chonetes and Streptorhynchus
were deposited.

156 PROFS. LLOYD MORGAN AND REYNOLDS ON THE [ May 1904,

EXPLANATION OF PLATES XVI & XVII.
Puiate XVI.

Map to illustrate the distribution of the Carboniferous volcanic rocks in the
Bristol district, on the scale of 2 miles to the inch.

Puate XVII.

Fig. 1. Olivine-dolerite or basalt from Goblin Combe eastern exposure.
This shows several crystals of serpentinized olivine, surrounded by
plagioclase-laths, the spaces between which are often occupied by
grains of augite. (See p. 152.)

2. Olivine-basalt from Milton Hill, Weston (not ¢z situ). A group of
three crystals of altered clivine is seen, and with them much ferric
oxide is associated.

53. Variolitic basalt from Spring Cove, Weston-super-Mare. Several
varioles are seen, varying considerably in size; also veins and amyg-
dules of calcite. (See p. 152.)

4. Calcareous ash from Spring Cove, Weston-super-Mare (3 feet above
the lava). This shows small basaltic lapilli, embedded in an abundant
matrix of calcite.

5. Calcareous ash from the extreme top of ash, Woodspring, exposure
(0). This shows abundant lapilli of amygdaloidal basalt, embedded
in a matrix of calcite. (See p. 154.)

6. Ashy oolitic limestone from Goblin Combe, eastern exposure.
This shows abundant oolitic grains and well-marked lapilli, embedded
in a calcareous matrix. (See p. 155.)

Discussion.

Mr. A. Srrawan said that he had listened with pleasure to the
careful description of these interesting rocks. The Authors had
added much to our knowledge; for they had not only recorded
two new occurrences, but (what was more important) had deter-
mined that the voleanic rocks of the various localities occurred
at the same horizon in the Limestone. The object of the traverse
made by Sir Archibald Geikie and himself had been mainly to
complete the Cardiff sheet of the l-inch Geological-Survey map ;
and although the advisability of subdividing the Limestone and
determining the horizon of the volcanic rocks had been discussed,
no opportunity had arisen of carrying out the work. With the
assistance of Mr. Vaughan, the Authors appeared to have proved
that the tuffs all occurred at the same horizon. He (the speaker)
had suggested that the vent lay somewhere to the west, probably
under the Bristol Channel. Whether tuffs could have been so
evenly and widely distributed from one vent only was perhaps open
to doubt. He congratulated the Authors on the interesting resuits
of their investigation.

The Cuarrman (Sir ARcHIBALD Gerxiz), alluding to the description
of the voleanic rocks given by Mr. Strahan and himself, to which
the Authors had referred, said that the examination of these rocks
had been undertaken by them, not with the view of making a
detailed study of the subject, but for the purpose of correcting the

—

Quart. Journ. Geol. Soc. Vol. LX, Pl. XVI.

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Vol. 6o. | IGNEOUS ROCKS OF THE BRISTOL DISTRICT. 157

erroneous interpretation which had prevailed and was expressed on
the maps of the Geological Survey. ‘The specimens first collected by
Mr. Strahan left no doubt in the speaker’s mind that the rocks in
question formed a volcanic series contemporaneously intercalated
in the Carboniferous Limestone. In order to put this question
beyond possibility of dispute, he subsequently went over the ground
with Mr. Strahan, and the description of the lavas and tuffs given
in the ‘Summary of Progress of the Geological Survey’ was the
result of that visit. His colleague and he could not attempt to
define the particular horizon in the Carboniferous Limestone on
which this voleanic intercalation lay, nor whether there were more
horizons than one. He was glad that their conclusions had been so
amply confirmed by the Authors of this paper; and especially that
the definite platform appeared to have been ascertained, on which
the records of the Carboniferous-Limestone volcanic eruptions of
the Bristol district had been preserved.

Prof. Warts enquired as to the exact method of occurrence of
the variolitic type in the lavas. Was it confined to lavas, or did
it occur in rocks the exact origin of which was unknown? Hecon-
gratulated the Authors on having determined, in this instance, that
the volcanic rocks occupied a definite horizon in the Carboniferous
Series.

Prof, Rrynotps, in reply to the last speaker, stated that varioles
were met with only in the rock from Spring Cove, of the con-
temporaneity of which there could be no doubt. The varioles only
occurred in certain parts of the rock.

158 MR. W. 8. BOULTON ON THE [May 1904,
oe

13. On the Ianzous Rocks at Serine Cove, near WerEsToON-SUPER-
Mare. By Witrtam S. Bourton, Esq., B.Sc., A.R.C.S8., F.G.S.,
Lecturer in Geology at University College, Cardiff. (Read
January 20th, 1904.)

I. Lyrropvucrion.

In the Summary of Progress of the Geological Survey for 1898
(pp. 104-11), Sir Archibald Geikie & Mr. Strahan, in a description
of a ‘ Volcanic Group in the Carboniferous Limestone of North
Somerset,’ published for the first time the evidence for the contem-
poraneity of these igneous rocks." The authors refer briefly to the
basalt and associated tuffs at Spring Cove, immediately to the west
of the town of Weston, and describe in more detail the basalt-lava
and beds of tuff interbedded with the fossiliferous limestone along
the ridge of Middle Hope, 2 miles north of Weston.

At the time of the publication of this account, I had already
made a detailed examination of these rocks in the field, and of
microscopic and chemical preparations ; but as my results seemed
in general accord with those of the authors named, especially in
regard to the rocks of Middle Hope, I felt that little or nothing
was to be gained by the publication of my work as a whole.

In the rocks at Spring Cove, Weston, however, there appear to
me to be points of considerable interest which are only briefly
touched upon, or not mentioned at all, in the account to which I
have referred, and I therefore venture to submit some additional
observations in regard to them.

IJ. Genprat Description oF THE Rocks.

The basalt at Spring Cove, immediately north of Weston Pier,
runs obliquely to the high road, and is exposed from low-water
mark along the foreshore into the face of the cliff, the exposed
length being about 150 yards. The massive beds of Carboniferous
Limestone, between which the basalt is intercalated, strike north-
eastward, and dip south-eastward (towards Weston) at about 40°.
The basalt-sheet is parallel to the bedding of the limestone, and has
a thickness of about 45 feet.

A traverse from end to end of the exposure shows clearly that
the rock varies considerably in structure and appearance, and that
it is by no means a simple basalt-lava fiow. Starting from low-
water mark, the rock is a hard, compact, red, shghtly-amygdaloidal

! In this account reference is made to the observations of previous in-
vestigators.

Vol. 60. ] IGNEOUS ROCKS AT SPRING COVE. 159

olivine-basalt, containing very occasional lumps of limestone,
from a few inches to afoot or more across. For the first 100 yards
its upper junction with the limestone cannot be seen, because of
the accumulated boulders at the foot of the cliff, while the lower
junction is covered with water, even at lowest spring-tide. Then,
a little more than halfway from the low-water end, and along to
the cliff, the basalt changes in character somewhat suddeniy. It
now contains big lumps of burnt limestone, and the whole mass
becomes broken up into a very coarse tuff or agglomerate, con-
taining great lenticular masses of highly-slaggy basalt, 5 to 6 feet
long, together with lumps and bands of limestone, often considerably
fractured, and up to 10 or 12 feet in length. About 20 or 30
yards farther on, and as far as the end of the exposure in the cliff,
the rock is more uniform in character, being a ‘ pillowy’ basalt,
though considerably brecciated and very amygdaloidal, with com-
paratively little tuff. But it still contains masses of limestone,
even larger than those in the middle of the exposure.

ee Fig. 1.—Lenticles of lava and tuff making
up the ‘main sheet of basalt.
/ (Lenyth=about 40 yards.)

The whole mass appears to consist of great lenticles of basalt, or
tuff, or both confusedly mixed, together with the included lime-
stone. The median planes of these lenticles run obliquely to the
limestone-beds above and below, so that the lenticles dip at a
steeper angle than the sheet as a whole (fig. 1). It would thus
appear that the mass is capable of being roughly divided into three
portions. Commencing at the cliff-end to the north (in which
direction the vent was probably situated), the rock for the first
30 yards is a ‘pillowy”’ basalt, with tuff and limestone often
occupying irregular spaces between the spheroids of amygdaloidal
basalt; then, for about 20 yards, the rock is mainly a coarse

160 MR, W. S. BOULTON ON THE [May 1904,

agglomerate, with lapilli and bombs of basalt and lumps of lme-
stone; while, for the remaining 100 yards or so, it is an ordinary
basalt-coulée, with very few, and always small, lumps of burnt
limestone.

III. RELATION oF THE BASALT TO THE LIMESTONE BELOW IT.

The basalt rests upon a hard bed of pink limestone, about 9 feet
thick. Immediately under the basalt the red coloration is intense,
but passes down into reddish-yellow and yellow; and the limestone,
especially in its upper portion, is markedly crystalline to the naked
eye. Below this bed is the typical, purplish-brown, fossiliferous
limestone about 25 feet thick; and this again is underlain by a soft,
pink, nodular rock, showing oblique lamination, and containing the
remains of corals and encrinites. This last bed is somewhat tuffy-
looking, but an examination of the residue, after treatment with
boiling hydrochloric acid, shows that it is an excessively-fine
red mud, without any recognizable volcanic lapilli, but probably
derived from some volcanic centre. This residue is in striking
contrast with those from the calcareous tuffs at Middle Hope, all of
which show abundant lapilli of basalt-glass, felspar-crystals, etc.

Sir Archibald Geikie & Mr. Strahan tabulate the following
succession of these rocks at Spring Cove (0p. cit. p. 105) :—

‘Massive limestone, full of fossils. The lowest 3 feet of the rock are crowded
with fine volcanic dust, which, under the microscope, is seen to consist of fine
vesicular lapilli.

‘Highly-amygdaloidal altered basalt, having a “ pillow ”-structure, and with
abundant calcareous and hematitic veins, and threads of carbonate of copper ;
about 35 or 40 feet.

‘Red: limestone, full of fine volcanic dust, and passing down into the
ordinary grey, fossiliferous limestone.’

In the limestone under the basalt I have been unable to detect
any undoubted igneous fragments, of the nature of volcanic dust or
lapilli (despite a diligent search in thin slices under the micro-
scrope), from the basalt-junction down to a depth of 9 feet in the
limestone. But the soft red rock, some 35 feet below the basalt,
may represent, as stated above, very fine volcanic dust, while a
section of the reddish-purple limestone, 8 feet below the basalt [ 23),
has a very tuffy appearance, as remarked below.

The following is a description of some of the sections cut from
this underlying limestone :—

[3| Reddish limestone, in contact with the basalt. The slice
clearly shows elliptical and rounded oolitic grains, set in a matrix
of calcite, occurring in small, irregularly-outlined crystals, and
with well-marked cleavage. As the rock approaches the junction
with the basalt, the oolitic structure gradually disappears, and the
rock comes to consist of a confused aggregate of minute calcite-

' The numerals in square brackets, throughout this paper, refer to the
numbers of the slides in the Author’s ‘ Weston collection,’

Vol. 60. ] IGNEOUS ROCKS AT SPRING COVE. 161

crystals, with no definite outlines or cleavage. With this change
comes in much reddish-brown colouring-matter, occurring in
irregular veins and fissures. In places the brown substance shows
distinct rhombohedra, sometimes with curved faces and projecting
into the vein, which is filled up with clear secondary calcite.
This brown substance, which is bright yellow and red by reflected
light, is doubtless carbonate of iron, carried down by percolating
waters from the basalt above, deposited in the limestone as chalybite,
and subsequently oxidized, giving to the limestone its pronounced
red tint, more especially for the first few feet below the junction.

[28] Another junction-specimen is a reddish-brown rock, with
the appearance of a breccia in the hand-specimen. Under the
microscope, the basalt can be seen penetrating and absorbing the
limestone. The contact has evidently much affected both rocks.
The basalt is represented at the actual junction by a host of minute,
pale-green or nearly colourless needles (? tremolite), which are
largely masked by iron-oxide. These needles are associated with
some brown and yellow glass and much secondary calcite, forming
a fine groundmass. The limestone is reddish-brown, structureless,
and polarizes faintly.

(24|] Another junction-specimen is intensely red, and shows
under the microscope the ‘ ghosts’ of the original volitic grains.

(21| A slice from a specimen taken 3 feet below the junction
shows, besides the usual reddish-brown ferruginous matter in the
spaces between the oolitic grains, which in places has a marked
superficial resemblance to fragments of palagonitized glass, a large
number of nearly colourless rhombs of dolomite, fringing cavities or
veins filled with water-clear calcite.

[23] A sample taken 8 feet below the junction, of a reddish-
purple colour, effervesces strongly with acid, and has a very tuff-like
appearance. Under the microscope it shows angular and rounded
fragments of oolitic limestone in a dark reddish-brown matrix, and
the borders of the fragments are strongly marked with the same
colouring-matter. But even here no certain igneous material was
detected, although it is possible that the highly-coloured matrix is
fine volcanic dust, and not colouring-matter brought down in
solution from the overlying basalt.

IV, Retation oF roe Basatr ro tHE LIMESTONE ABOVE IT.

The determination of the precise nature of this junction is
obviously important, as bearing on the contemporarieity or intrusion
of the basalt. In the Survey account referred to above it is stated
(p. 106) that
‘fine voleanic dust appears in the overlying limestone for about 3 feet above the
surface of the lava, and thereafter the calcareous rock assumes its usual highly-
fossiliferous character.’

I have cut and examined sections at and near the junction and for
about a foot above it, and can confirm the above observation. At
the actual junction, and for about a foot from it, lapilli of basalt, one-

Q.J.G.8. No. 238. M

162 MR. W. S. BOULTON ON THE | May 1904,

eighth to one-sixteenth of an inch across, are very numerous, often
with the typical concave surfaces, due to fracture across vesicles.
In among these lapilli, caleite-crystals occur, and round their borders
is a brown, yellow, or red ring of iron-oxide derived from the basalt-
fragments, while fringing some lapilli are clusters of small, pale-
yellow rhombs of dolomite, showing patches of bright yellow and
borders of red irom-oxide by reflected light.

V. Some Sprcian CHARACTERS OF THE BAsALt-SHEET,

The characters of this igneous flow which are of especial interest
are (a) the * pillowy’ structure, together with the tuffy or agglome-
ratic structure; and (/) the included lumps and masses of limestone,

Fig. 2.—Oval, slagyy lumps of basalt-lava surrounded by

fluxion-tuff.

Fig. 3.

Lump of basalt-lava, enclosing a lump of tuff and of lime-

stone, anil rtself enclosed in coarse fluxion-agglomerate.

Ly
7LIMEST.

The pillowy, oval, or spheroidal masses of basalt, 2 to
8 feet across, usually very amygdaloidal, especially round their
periphery, and sometimes coutaining small oval or angular cores of
a slightly different and earlier lava, are usually embedded in a tuff
made up of lapilli up to 2 or 3 inches across (figs. 2 & 3).

.

Vol. 60.] IGNEOUS ROCKS AT SPRING COVE. 163

Near the middle of the sheet, covered and underlain by massive
lava, is a band 5 to 6 feet wide, with a dip roughly parallel to the
other lenticular masses, consisting of a confused mass of coarse
tuffy material, made up of angular fragments of lava 1 to 2 inches
across, embedded in a fine red-and-green matrix, and containing
lenticular cakes of vesicular lava, phacoids (often broken and
torn) of limestone, and higher up the cliff larger spheroidal lumps
of lava. The whole band suggests forcibly the augen-structure
characteristic of gneisses. It probably represents, however, a torrent
of agglomeratic material that flowed down a slope on the surface
of an already-extruded bed of lava, carrying in among the finer

Fig. 4.—Band of coarse agglomerate
in the basalt-lava.

Linm.= Limestone.
Bas.= Basalt.

lapilli larger, irregular, and plastic masses of scoriaceous basalt-lava
of the nature of bombs, together with lumps and fragments of lime-
stone, which from their torm and broken character suggest that
they were ejected from the vent with the basaltic material (fig. +).

In all cases where the phacoidal or lenticular structure is seen,
whether on a large or on a small scale, the material forming the
groundmass is fragmental and tuff-like, while the included phacoidal
masses consist of vesicular lava, or limestone, or very occasionally
masses of coarse tuff (figs. 2, 3 & 4).

A thin slice of the typical tuffy matrix [20] shows small sub-
angular or rounded, closely-fitting, equal-sized Supe about an

mu 2

164 MR. W. S. BOULTON ON THE [May 1904,

eighth of an inch across, with little or no interstitial matter except
secondary calcite and iron-oxide. The lapilli consist of basalt-glass
crowded with felspar-microlites, and in all general characters suggest
strongly an analogy with the ‘ volcanic sand’ of the recent West-
Indian eruptions, so graphically described by Dr. T. Anderson &
Dr. J. 8. Flett.’

It is highly probable that this basaltic mass, like other pillowy
lavas containing portions of sedimentary material, was ejected under
water; and it is certain, | think, that the tuff or agglomerate was
not in the main forced into the air by an eruption and deposited in
the sea-water. ‘There is no evidence of sedimentation, or the quiet
accumulation of dust and lapilli ; all the appearances point to flow.
It might be termed a fluxion-tuff or agglomerate.

Possibly, if the vent had been situated in very shallow water, or
on the land, much of this fragmental material would have been
blown into the air, fallen in the water, and settled down quietly on
the sea-floor, as, indeed, appears to have been the case with much
of the tuff at Middle Hope, 2 miles to the north. At Weston,
however, the greater weight of water above may have prevented
this, and compelled the fragmental material to flow as lava. Or
again, as in the West-Indian examples already cited, the expansive
force of the imprisoned vapours may have been sufficient to break
up the lava within the vent, but insufficient to do more than just
force the tuff over the lip of the vent, whence it flowed along the
sea-floor in obedience to gravity, and impelled forward, in part, by
the expanding gases. L

a

One of the most remarkable features of the sheet is the abundance
of lumps and irregular masses of limestone, enclosed in the
amygdaloidal and ‘pillowy’ basalt, or occurring as phacoids and
lumps in the tuffy material.

In the accompanying diagrams (figs. 5, 6,7 & 8, pp. 165-67) some
of these masses are shown, ranging in size up to 10 or 12 feet, often
broken and torn, in part eaten into and absorbed by the basalt, and
sometimes tailing off into smaller and smaller fragments. Charac-
teristic features are the concave surfaces of the limestone, often due to
the fact that the latter occupies an irregular space between a number
of spheroids or ‘ pillows’ of the basalt, looking as if either the lime-
stone had been absorbed by the hot lava, or, more probably, squeezed
into its present shape by the distending and moving spheroidal
masses.

There can be no doubt that this limestone is not secondary, due
to the deposition of calcareous material from aqueous solution
subsequent to the outflow and consolidation of the lava; nor has it
been deposited as sediment in irregular spaces between the spheroids
after the cooling of the basalt ; but it is unquestionably part of the
calcareous floor upon which the basalt-flow rests. Many of these
included masses are oolitic, the structure being visible sometimes to

~ Phil. Trans. Roy. Soe. ser. A, vol. ce (1903) pp. 448-49.

Vol, 60. | IGNEOUS ROCKS AT SPRING COVE. 165

the naked eyc, while a microscopic examination shows the oolitic
grains distinctly, together with the remains of encrinites, ete. ; and

the basalt has penetrated, fused, and absorbed the limestone along
its borders.

Fig. 5.—Junction of the basalt and an included mass of lamestone.

A thin slice through the junction of the basalt and an included
mass of limestone [30 c| shows that the basalt, here a brown, yellow,
red, or green glass, in places distinctly variolitic, penetrates and
absorbs the limestone, which is turned yellow and red, owing to the
staining of iron-oxide; while, along the edge of the limestone at

166 MR. W. S, BOULTON ON THE [May 1904,

the junction, occur wavy bands of reddish-brown and yellow
alteration-material, reminding one of agate-structure. Here, as

Fic. 7. Limestone included in basalt.

in the limestone under the basalt, rhombs of chalybite fringe the
walls of drusy cavities and veins, the rest of the space being filled

Vol. 60. ] IGNEOUS ROCKS AT SPRING COVE. 167

in with clear secondary calcite, while limonite and hematite have
been subsequently deposited.

In some instances the limestone, more especially that occurring
as irregular lumps in the tuff, is so cracked and broken, evidently
during the movement of the flow, as to suggest that it must have

Fig. 8.—Portion of an included lump of limestone in basalt.

BASALT EE] + +. 2

ZO. CZ Ke a NE

been hard and consolidated before the extrusion of the lava, and
was probably torn from the vent and ejected with the igneous
matter.

Small oval bodies, generally a few inches long, occur in the basalt;
these, when broken, show a yellow or red shell of carbonate of lime,

168 MR. W. S. BOULTON ON THE [May 1904,

the rest being filled with pure white, secondary calcite, and in some
cases quartz ; indeed, in a few instances, rounded or oval bodies up
to a foot in length consist entirely of silica. These may be lumps
of limestone, burnt and hardened on the outside by the hot lava,
their centres being subsequently removed in solution, the hollows
thus formed serving as receptacles for secondary calcite or quartz ;
while in a few cases the whole lump of limestone has been replaced
by silica. It is possible, however, that some of them may be large
vesicles filled with secondary minerals.

But, in most cases, the general shape and behaviour of the Jime-
stone-masses, particularly between the spheroids of basalt, seem
rather to suggest that the calcareous material must have been only
in part consolidated, so that it behaved as a pulverulent or more or
less plastic substance, and got rolled in or picked up by the lava,
and was able to fit itself in between the moving and distending
spheroidal masses.

In this connection, it is interesting to compare the general shape
and appearance of these included masses with those in other
localities, as, for example, in the Arenig lavas of Ballantrae and
elsewhere, with their marked pillowy structure, so well illustrated
and described by Sir Archibald Geikie and the officers of the Geolo-
gical Survey." There the included material is jasper, radiolarian
chert, graptolite-shale, and limestone. In the memoir describing
these rocks in the Ballantrae district it is stated (op. cit. p. 452)
that
‘the calcareous matter does nct seem to have penetrated far down through °
the successive beds, being confined mainly to the surfaces of the flows.

In the case at Weston it must be admitted, as already pointed out,
that the calcareous material did not come from above,
but from the underlying floor.

In the account of these Weston rocks by the officers of the Geolo-
gical Survey, it is suggested that the vent from which the rocks of
Spring Cove were derived lay somewhere to the west, where now
the Bristol Channel lies ; but from the fact that the included masses
of limestone dwindle rapidly in size and number from north to south,
and that the lenticular sheets of lava and tuff, representing indi-
vidual minor flows, also slope from north to south, it would seem
more probable that the vent lay somewhere to the north of this
Spring-Cove exposure.

Except for the presence of lapilli of basalt in the base of the
limestone resting at once on the basalt, it might be difficult to show
that the whole is not an intrustve sheet. ‘The conditions in these
submarine flows appear to be very like those in a sill or intrusive
sheet, where, as Prof. Lapworth has suggested, we may get tufts,
lava, and included masses of sedimentary material confusedly mixed,
and drawn out into lenticles as here described.

1 Mem. Geol. Sury. (1899) ‘ Silurian Roeks of Britain’ vol. i, Scotland.

Vol. 60. | IGNEOUS ROCKS AT SPRING COVE. 169:

Discussion.

The Cuairman (Sir AncurpaLp Gerkie) remarked that, since the
publication of the joint description with Mr. Strahan, referred to
by the Author, he had had an opportunity of re-examining the fine
series of intercalated lavas in the Carboniferous Series of Fife. In
most, if not in all, of those basalts which show the pillow-structure
the materials that now fill up the interspaces between the ellipsoids
have come from above and evidently belong to the series of sedi-
ments—tuff, sandstone, shale, limestone, etc.—which followed the
emission of the lava. There is no trace of an explosive character
in the lavas themselves; and he greatly doubted the possibility of
a lava which had once escaped from the vent and flowed for some
distance, subsequently blowing itself to pieces by the expansion of
its own imprisoned vapours. No doubt, sudden contact with water
might cause some lavas to break up; yet it was nevertheless the fact
that in the case of those in question, though they had all flowed
out over the bottom of a lagoon or the floor of the more open sca,
none of them showed more than the usual irregular cracked surfaces.
He did not think that there was ever much resemblance between the
behaviour of a silland that of a submarine lava-flow. He welcomed
the additional information now supplied regarding an exceedingly-
interesting little voleanic district, and hoped that the Author might
be induced to study the other exposures in the same careful and
detailed manner.

Prof. Warrs remarked that the paper constituted a very important
contribution to volcanic geology. It enabled us to realize that con-
ditions of vulcanicity prevailed in Carboniferous times similar to the
vuleanicity of the present day. He was greatly impressed with
the suggestion that the eruption described in the paper was of the
Peléan type: the lava was blown to atoms, and the pulverized material
formed a fluxion-tuff. In the Llandeilo of the Shelve district the
speaker had formerly been perplexed how to classify a rock similar
to that described by the Author. There was no reason why lava
_ should not be blown to dust beneath the sea as well as on land, and
the pressure of the water would induce conditions reminiscent of
an intrusive sill. The Author had satisfactorily proved that most
of the sedimentary material caught up in the lava had been derived
from below, and his evidence was not inconsistent with that brought
forward by the Geological Survey from the Southern Uplands of
Scotland.

The Avuruor thanked the Fellows for their reception of the paper.
He quite agreed with the Chairman that limestone, and sedimentary
material generally, found within the body of pillowy lavas, might
have come about in different ways in different cases, and that in
some cases the material had doubtless come from above, either in
solution or as sediment; but, from the evidence at Weston, it appeared
certain that it might have come from below, ejected from the vent
or picked up by the moving lava from the sea-floor. He did not
think that it was necessary to assume a great depth of water at
Weston during the outpouring of the lava.

170 MR. A. RENDLE SHORT ON RUZETIC [May 1904,

14. A Descriprion of some Ruaztic Srcrions in the Brisrot Disrricr,
with CONSIDERATIONS on the Move of Deposition of the Rumric
Series. By A. Renpre Sxort, Esq., B.Sc., M.B., B.S. (Com-
municated by Prof. 8. H. Reynotps, M.A., F.G.8. Read
December 16th, 1903.)

ConTents.
Page
I~ Introduction’ 2. i... si0di.teesneteeeeom- at eewsun sae eaten ae eo 170
II. Description of four new Rheetic Exposures ss RRL a beads Soma 170
(A) Redland, Bristol.
(B) Stoke Gifford.
(C) Cotham Road, Bristol.
(D) Aust.
III. The Physical Geography of the Rhetic Period ............... 179
IV. The Stratigraphy of the Rheetic Series’...........2..2:02.0:2.4 + 187
M BUMMALY ssc sss paehe sen oneaseneOss anne ste acknn seo eee eee 189
Vi> Bibbosraplty san-.vcscssoss cine bb tistovae amin ada a Be enn es 120

I. Iyrropucrion,

Tus paper is a condensation of a longer memoir, the parts omitted
being chiefly lists of fossils and remarks on the same. It embodies
the results of some five years’ study of the Rheetic Series, chiefly in
the Bristol district, made easier by the fact that I reside in that
district. .

Il. DescrIPrioN OF FOUR NEW RuztTic Exposures.

(A) Redland, Bristol.

A number of exposures have been recently made here in cutting
a new road. One of these has already been briefly dealt with
in a local memoir by Mr. W. H. Wickes (46),’ and again by
Mr. Parsons (47). I give, with slight modifications, Mr. Wickes’s
classification of the beds, and his list of fossils, enumerating those
that I have found in addition. The lettering corresponds to that
used by the late Edward Wilson for the Pylle-Hill section (36).
The fossils are not obtained solely from the exposure originally
described, but from the newer exposures as well. It is imprac-
ticable to separate them, as the material thrown out has been
mixed.

Feet inches.

S. Five beds of hard, blue, 2 Sa. (In the upper two bands.)
shelly limestone, with Ammonites torus. (Am. planorbis
brown shaly partings. found, but not in place.)
}. (In the lower bands.)

LTleuromya Crowcombeia, Modiola
minima, Cardium rheticum, Pecten
Pollux, Monotis decussata (rare).

1 Numerals in parentheses thioughout this paper refer to the Bibliography
§ VI, p. 190.

Rad ia!

Vol. 60. ] SECTIONS IN THE BRISTOL DISTRICT. ETE

Thick hard limestone ...
. Rubbly limestone.........

Ow

P. White shaly and rubbly

limestone.

O. Yellow clay-parting ...

N. Cotham Marble, a con-
tinuous band.

M. Blue and brown and
greenish clay, with white
shaly partings.

L. Thinly-bedded, siliceous,
white limestone.

K. More thickly-bedded but
fissile, siliceous limestone
(see below).

I. Dark, shelly, hard,
thickly - bedded _ lime-
stone, weathering brown,
but with a bluish-black
core.

H. Dark shaly clay .........
G. Limestone resembling I,
with a layer of fibrous
calcite (=‘ beef’) aboveit.
F. Crumbly black shales ...

Feet inches

0 5
) «
0 9
i) 13
0 8
2 0
i 0
2 0
i) 8
i) d
0 +
3 9)

c. (Precise horizon not specified.)
Ostrea liassica, O. levis, O. imulti-
costata, O. irreqularis, Lima gt-
gantea, L. valoniensis, L. het-
tangiensis, Pecten calvus, P. dispar,
Cardinia Listeri, Pholadomya gla-
bra, Plicatula intusstriata, Uni-
cardium sp.; Rhynchonella calci-
costa, Terebratula sp.; Nautilus
striatus: Cidaris Edwardsi (%)
spines; Pentacrinus ; Montlivaltia
sp.; Serpula sp.; burrows, ete.

Similar fossils to 8.

Pleuromya Crowcombeia, Cardium
rheticum, Plicatu/a intusstriata.
Modiola minima, Pleuromya Crow-
combeia, Cardium rheticum, Pli-
catula intusstriata, Pholadomya
glabra, Arca (!) Lycetti, Monotis
decussata. (Mr. Wickes records

insect-fragments. )

Modiola minima, Monotis decussata,
Chemnitzia nitid.
Plesiosaurus-yertebra; Darwinula.

( Barren.)

Naiadita lanceolata (very abundant),
Axinus cloacinus, Cardiun rheti-
cum, Pecten valoniensis (a few),
Myacites sp. ; Estheria minuta, Dar-
winula; Acrodus minimus, Hybodus
minor, Saurichthys acuminatus,
S. apicalis, bones, coprolites.
(Mr. Wickes records Pholidophorus,
Lepidotus,and Legnonotus.)

Pecten valoniensis (very abundant),
Axzinus cloacinus, A. concentricus,
A. elongatus, Cardium rheticum,
C. cloacinum, Cardinia regularis,
C. suttonensis, Modiola minima,
Pleurophorus eiongatus, Pleuromya
Crowcombeia, Plicatula tntusstriata,
Gervillia precursor, Anomia valo-
niensts; Discina Townshendi; Gyro-
lepis Alhertii, Saurichthys apicalis,
S. acuminatus, Acrodus minimus,
Hybodus minor, H. cuspidatus ;
Termatosaurus Alberti, T. cro-
codilinus, Spherodus minimus ;
coprolites, scales, spines, ete.

(Barren.)

Avicula contorta, A. solitaria, Axinus
cloacinus, Pecten valoniensis,
Modiola minima.

(Just here I have found no fossils.
The Lower Rhetic is better dis-
played in a fresh section.)

Such is the original exposure, which furnished the material for

Mr. Wickes’s paper.

172 MR, A. RENDLE SHORT ON RHZETIC [May 1904,

The next section to be opened, about a quarter of a mile or less
away, displayed upturned beds of Upper Carboniferous Limestone,
cut off flat, with the Rhetic Beds deposited on them unconformably.
The iimestone-beds are very massive, and dip at 35° south 80° east.
Between these beds little pockets of yellow clay pass down for a
variable distance, due to greater erosion along the planes of
stratification.

On the east, the Carboniferous platform gradually slopes down at
an angle of about 10°, quickly becoming steeper, beneath the Rheetic
Beds, and is lost to sight. The Rheetic Series overlying this has
been briefly touched upon by Mr. Parsons (47), who explored it
with me in the first place, but since then I have found the Bone-
Bed and many more fossils. .

Feet inches,

S. Three beds of bluelime- _..... Ostrea liassica, Modiola minima,
stone. Pleuromya Crowcombeia, Phola-
domya glabra, ete. Noammonites.
R. Thick, hard, blue lime- 0 5 (Same fossils as above.)
stone.

Q. Rubbly white limestone
(incompletely exposed).
A short distance from this, the Rhextic Series is again exposed.
N. (Cotham:Marhle:...:=... 0 4to8 Modiola minima, Monotis decussat
an insect-wing.
M. Laminated blue and 2 0 (Barren. )
yellow clay.

K, L. Naiadita-teds ...... 2 0 A very few specimens of Noiadita.

I. Inconstant black lime- 0 4to6 Pecten valontensis (abundant), Axinus
stone, weathering cloacinus, Modiola minima, teeth
brown. and scales of fishes.

H, F. Black shales, crumbly
above, bard and fissile
below ; with ferruginous
bands 5.482802 about 6 0 (Barren. )

About 3 feet down are a few nodular, red limestone-masses, con-
taining Avicula contorta, Modiola minima, and Placunopsis alpina.

Feet inches.

A. Bone-Bed ...... 0 2 Acrodus minimus (very abundant), Gyrolepis
Albertiti and Saurichthys acuminatus (abun-
dant), S. apicalis, S. listroconus, Hybodus
minor, H. cuspidatus, H. orthoconus, H. rari-
costatus, H. sublevis, Spherodus minimus,
Squaloraia (2), Sargodon tomicus, Sphenon-
chus hamatus, Termatosaurus Alberti (2),
T. crocodilinus ; various doubtful fossils
discussed later, coprolites, ribs, vertebrie,
scales, bits of bone, and Hybodus-spines.

The most interesting bed in this series is the Bone-Bed. It lies
directly upon the flat, eroded edges of the Carboniferous-Limestone
strata, and is so tightly cemented to them that, on hammering, it
nearly always breaks up instead of separating from the limestone.
Its thickness is very variable, and it is over considerable areas

Vol. 60. | SECTIONS IN THE BRISTOL DISTRICY. 173

absent. Jn the clay-pockets that lie between the beds a very few
teeth may be found. It never fills up these pockets, but is only
found on the cut-off surfaces of the limestone-bands.

The Bone-Bed contains very numerous fish-remains, all except
the smallest being fragmentary. tightly cemented together by a
reddish-brown, gritty, calcareous sandstone. The whole is very
hard, and fossils are difficult to knock out entire. In addition
to the teeth, scales, and bones mentioned above, there are :—
(1) numerous coprolites, sometimes an inch in diameter ; (11) small
rounded quartz- -pebbles, with a peculiar resinous surface i in many
cases, varying in size from that of a millet-seed to that of a small
walnut; (iii) angular or subangular pebbles of Carboniferous Lime-
stone ; and (iv) well-rounded pebbles of sandstone from the Upper
Carboniferous-Limestone Series, fairly numerous, and often measuring
2 inches in diameter.

Between the two exposures above described, an extensive cutting,
displaying the Lower Rhetic beds especially, has been made; the
succession is as follows :—

Feet inches,

Q@. Rubbly limestone. 2 )

N. Cotham Marble, very O 4to6
inconstant, in patches
about a yard across, and
4 to 6 inches thick.

M. Laminated blue and 3 4
yellow clay, with white
bands.

K, L. Naiadita-beds — fis-
sile, thinly - bedded,
cream-coloured lime-
stones.

I. Hard, dark, shelly 0

to
CS

Naiadita lanceolata, ete.

Or

Pecten valoniensis (very abundant),

limestone, weathering other fossils as in the first section.
brown.

H. Shaly parting............ 0 4

G. Limestone likeI;‘beef?’ O Sto8 Avicula contorta, Pecten valoniensis,
above and below. etc.

(The shaly parting is in places absent, and G and I are then conjoined.)

F.—II. Crumbly black 2 0 Avicula contorta, Pecten valoniensis,
shales and clay, with Axinus cloacinus, A. concentricus,
siliceous bands, con- A. depressus, A. elongatus, (2) Ana-
taining Cardium rhe- tina Suessi, Cardium rheticum ;
ticum. Gyrolepis Albertii, Hybodus minor,

Saurichthys acuminatus.
I. Thin but constant
ferruginous band.
HK. Ill. Black laminated 2 0

clay.

IJ. Ferruginous band.

1. Black and green 1 0 Avicula contorta, A. solitaria, Axinus
laminated clay. cloacinus, A. depressus, Cardium

rheticum, Gervillia precursor

(young), (i ’) Anatina Suessi, Placu-
nopsis alpina,

74 MR. A, RENDLE SHORT ON RH ETIC [May 1904,

Feet inches.
D. Thickly-bedded, fissile, 1 9 Very barren; a few specimens of

hard, black shales, not Axinus cloacinus and A. concen-
crumbly: = ‘ Paper tricus.

Shales, with —shaly

concretions.

C, A. III. Bone-Bed, con- 0 2 Very few organic remains, except
taining Carboniferous- coprolites; Acrodus minimus, Saur-
Limestone and sand- ichthys acuminatus, Gyrolepis Al-
stone - pebbles; very bertit.
crumbly.

II. Green and black 0 6 (Barren.)
marl,
J. Ferruginousband 0 1
(Krvurer). I]. Brown sand- 0 Otod
stone (variable).
I. Hard,sandy,green 3 0

and brown marl-
stone, with den-
dritic markings.

This section is of interest, as showing how ill-developed the Bone-
Bed becomes when receding from the old shore ; as it is not coherent,
it is not very recognizable.

The next exposure to be considered is beyond that described
second (p. 172). Here, in laying a sewer, another interesting
succession came to light :—

Feet inches.

R,S. Blue and white 4 2, Fossils as usual.)
J .
Lias, ete.
P,. Hard, white, fine- 0O 3 Monotis decussata.

grained limestone.
O. Hard, thickly-bedded, 0 6 Modiola minima, Monotis decussata ;
black shale, crumbly on Gyrolepis Albertit.
its upper surface.
N. Cotham Marble, chiefly 0 3sto6
of the variety which I
have described as ‘ False
Cotham Marble’ (53).
M. Blue and _ yellow
rol, eee cee ee about
K, L. Natadita- beds, not
seen in place.

lo
=
SS

Instead of being cream-coloured fissile limestones, these beds are
thin, hard, sandy, argillaceous slabs, breaking into thin but large
pieces. They are grey in colour, and often sprinkled with tiny
mica-flakes. They are, moreover, extensively ripple-marked, the dis-
tance between the waves being usually about 2 inches. Exquisitely-
preserved worm-tracks, sometimes 3 inches long, are very common.

Yet another exposure remains to be described, but it is in the
Trias rather than the Rhetic. Still, it throws light on some of the
problems of the latter series. It is situated nearer Bristol, about a

Vol. 60. | SECTIONS IN THE BRISTOL DISTRICT. 175

quarter of a mile away, at a level about 20 or 30 feet below the
Black Shales. The succession is :—

About 1 yard of surface-soil.

V. Red marl: 2 feet.

IV. Celestine-bed: 2 to 8 inches.—Rather inconstant, confined to the one
horizon.

III. Red marl: 3 inches.

If. Hard typical green marl: 4 inches.

I. Red marl: 15 feet.—Contains a few calcareous plates and nodules. At
the top it is full of nodules about the size of a cricket-ball, composed
of carbonates of strontium and calcium, in the proportion of 37°63 per
cent. of the former, and 62°36 per cent. of the latter.

The celestine, IV, contains an unusual proportion of strontium-carbonate
(SrSO,=68°43 per cent. ; SrCO,=31°56), and is badly crystallized, but shows
a distinct blue colour.

The whole Rhetic Series described above dips gently east-
north-eastward at a somewhat variable angle, usually about 10°.
On the Cotham-Marble horizon the rare mineral baryto-celestine
may be found, chiefly in drusy cavities inside concretions.

Since writing the foregoing account, { have found in the Pecten-
valoniensis zone two or three ovoid, well-rounded blocks looking
exactly like charred wood. On analysis, these turn out to be chiefly
carbon and carbonate of lime, with no phosphate, so that they can
be neither bone nor coprolite, and indeed must be fragments of
drifted wood. As they measure, though very incomplete, ? by } inch,
there must have been trees or very big bushes growing near the
water, or by streams, at that time.

Messrs. Tutcher & Vaughan have described the Lower Lias and
White Lias of these sections in a paper published in February 1903
by the Bristol Naturalists’ Society (52).

(B) Stoke Gifford.

In a railway-cutting recently made in connection with{the new
line from Filton, near Bristol, to Wootton Bassett, the Rheetic has
been well exposed at Stoke Gifford, quite close to Filton.

The whole series dips at 5° towards 10° west of north.

The Lias has been described by Messrs. Reynolds & Vaughan (50),
and it is unnecessary to repeat their description, except to.add that
I found Monotis decussata in their * Ostrea-beds.’

The succession is as follows :—

Feet inches,
N. Cotham Marble, in a 0 4 Rhynchonella calcicosta ; Axinus s
continuous band. Top Monotis decussata.
not so ridged as usual.
M. III. Grey laminated 2 QO (Barren.)
marl,
II. Thin but constant 0
band of siliceous lime-
stone.

nD
her J

Or

(The thickness of the Rhetic Series here = 21 feet.)

| May 1904,

Brodieana ;

but about 10

Pteromya

Anatina Suessi, ,
Cardium
Ptero-
Pt. simplex ;
Aybodus-spine,

(Very barren.)

176 MR. A, RENDLE SHORT ON RI_ATIC
Feet inches.
I. Grey laminated 3 3. Estheria minuta, var.
marl, with mica-flakes. insects.
More _ thickly - bedded
siliceous layers at the
base, showing ripple-
marks, the ridges run-
ning north-eastward and
south-westward.
L, K II (a). Massive but 2 0 (a) Usually barren,
banded, grey, siliceous inches down are several horizons
limestone on the north of Estheria minuta.
side of the cutting.
(b) On the south (0) Natadita lanceolata on the south
side, thinly - bedded, side.
cream-coloured, fissile
limestone like the Naia-
dita-beds of Redland.
I. Greenish-black cal- 1} 0) Pecten valoniensis, Axinus depressus,
careous shales (absent on Cardinia suttonensis,
the south side). Many of Crowcombeia, Saurichthys acumi-
the fossils are pyritized. natus, Gyrolepis Alberti, Naiadita
lanceolata, and especially many
elytra of beetles and wings of in-
sects, usually fragmentary.
J-H. Black flaky marl, very O 10 LPecten valoniensis (very abundant),
fossiliferous. Avicula contorta (scarce), Axinus
(Messrs. Reynolds & depressus, A. concentricus, A. cloa-
Vaughan found here a cinus, A, eongatius,
hard black limestone - (!) Gervillia ornata,
band with Peczen). rheticum, C. cloacinuna,
mya Crowcombeia,
Gyrolepis Albertii,
Saurichthys-teeth,
G. Dark siliceous limestone. 0 3. A few fish-scales,
F. IJ. Crumbly black shale. 5 0
J. Pyritous sandstone... 0 02
K. Crumbly black shales, 2 6 Avicula contorta, Axinus depressus,
with pyritous sandstone- A, cloacinus, A. concentricus, A.
bands, 15 and 22 inches elongatus, Cardium rheticum, C.
respectively below F I. cloacinwin.
D. Hard, thickly-bedded 2 Q Axinus; Gyrolepis,
black ‘ Paper-Shales.’
‘C, B, A. (Absent.)
{ V. Grey, fine- 5 0
| grained, argil-
laceous sand-
| stone.
KEUPEES TV. Greyahales, 95 0
YUL, Redimarl... J 6
| II. Grey shales. 0 8
| I. Red marl ... 12 feet exnosed.

The principal features of interest are: the continuous well-
developed Cotham Marble; the insect-bed; the poor development.
of the Pecten-valoniensis limestone ; and, finally, the absence of the
Bone-Bed.

Vol. 60.] SECTIONS IN THE BRISTOL DISTRICT. 177

(C) Cotham Road, Bristol.

The next section to be described was exposed for a few days, in
cutting a channel in connection with the Oakfield Road Waterworks.
It is interesting as passing Cotham House, where Edward Owen
first found Cotham Marble in 1754. Although incomplete above
and below, there are features that make it well worth recording.
I may say that, as more than a few feet of the section were never
exposed in one place, the measurements are rather approximate.

Feet inches.

S. Hard blue limestone, Ostrea Tiassica, Pleuromya Crow-
weathering _yellowish- combeia, Modiola minima.
brown. (Not found in
place.)

N. Cotham Marble, poorly 0 6
developed, usually absent.
A few poor ‘landscape-
stones.’ Frequently re-
presented by concretions
(see p. 178).

M. Yellow marl .............. 1
L, K. Hard, yellow, fissile 3
limestone, like the Naia-
dita-Beds at Redland.
Lower down, it becomes
very massive, not fissile,
with a grey homogeneous
core and yellow exterior.
Usually barren, but splits

along surfaces covered with Natadita lanceolata,

There are also many Pecten valoniensis, Cardium cloaci-
bands, about a quarter of num, Cardinia regularis, Modiola
an inch thick, of brown, minima ; Acrodus minimus, Gyro-
very shelly limestone, lepis Albertii, Sawrichthys acumi-
sometimes jointed into natus ; coprolites.
tiny squaresand polygons.

The shells are arranged
horizontally parallel one
to the other, in a way
very suggestive of Pur-
beck Marble.
1. Thick, hard, shelly, non- 0 4to6 Pecten valoniensis (very abundant),
jointed black limestone. Axinus cloacinus, A. concentricus,
A, depressus, Cardium rheticum,
Modiola minima, Anomia valoni-
ensis, Monotis sp., (2) Gervillia
ornata ; Natica Oppeli ; Gyrolepis-

oO

scales.
H,G. (Absent.)
F, E. Crumbly black shales, Avicula contorta (largeand abundant),
with pyritous flakes; a A. solitaria, Pecten valoniensis (only
few thin siliceous bands. at the top), Arinus concentricus, A.

depressus, Cardium cloacinum, Myo-

phoria Emmrichi (very perfect and

abundant), Modiola (/) minima,

Placunopsis alpina; Gyrolepis

Albertti ; pyritous elytra of beetles.

D. Hard, more thickly-bed- A. few specimens of Avicula contorta
ded, black ‘ Paper-Shales.’ and Axinus.

Bone-Bed (absent).

Q.I.G.8. No. 238. x

178 MR A, RENDLE SHORT ON RHZTIC [May 1904,

The Black Shales are about 15 feet thick: the fossils in them
are the best that I have ever seen. Below come about 15 feet of
yellowish marl and then red sandstone, but this part of the section
was very indifferently exposed.

The horizon of the Cotham Marble is interesting. It is remark-
able that at the very birthplace of the name, so little good ‘ land-
scape-stone’ should be found. Instead, there are several large, flat
concretions of a texture very like that of Cotham Marble, about
13 feet in diameter and 4 to 6 inches thick, revealing cavities
in their interior, lined with calcite and containing the rare mineral
baryto-celestine, of a pale-blue colour, in which the sulphates of
strontium, barium, and calcium are all found.

The beds K & L are of considerable interest also. They are much
more massive than at Redland, and show no ripple-marks or sun-
cracks. It is remarkable how the Naiadita keeps to special
horizons containing no other fossils. Careful search failed to reveal
Estheria minuta.

Finally, we may note the apparent absence of the Bone-Bed.

(D) Aust.

It may, perhaps, be thought that on so classic a section as Aust
nothing new could have been written. For many years it has been
one of the type-exposures of the Rheetic, and Agassiz had immor-
talized its vertebrate fauna long before the Rhetic Beds were
recognized as a formation. The principal references to Aust are by
Agassiz (‘ Poissons Fossiles’), Etheridge (15), Davis (29), and the
Clifton-College Scientific Society (18). Of these, the detailed
account of the stratigraphy is given by Etheridge, whose table I
copy and supplement. Now in this table a vacancy of 13 feet was
left at the top, in a most interesting series of beds, because they
were inaccessible from below. I therefore had myself let down
from the top of the cliff by a rope, measured this gap, and
studied its contents both in place and in fallen pieces :—

No. Feet inches. Formation. Fossits.

23, Ae QO? Miblme Was) 2.5. tees Ostrea liassica, O. multicostata,
Pleuromya Crowcombeia, Pecten
Pollux.

22. 0 Sto8S Cotham Marble ............ Modiola minima, Monotis decus-

sata ; Gyrolepis Albertii, Pholi-
dophorus Higginsi, Saurichthys
apicalis, Legnonotus cothanensis,
Spherodus minimus ; insect-
wings and elytra.

A 2. ~ Yellow shaly claye..is<-- (Barren.)
20. 2 6G Hard, fine-grained, argil- Naiadita lanceolata; Lstheria
laceous limestone, cream- minuta.

coloured outside, greyer
inside ; often fissile.
19,5 Q Yellow,thinly-bedded,very (Barren.)
argillaceous limestone,
often crumbly.

Vol. 60. | SECTIONS IN THE BRISTOL DISTRICT. 179

No. Feet inches. Formation. Fossits.

i 0 5 Upper Pecten-Bed, hard Pecten valoniensis, Placunopsis al-
grey limestone. Usually pina. Locally it is thinly-bedded
double, with 4 inches of and crowded with Acrodus mi-

shale intervening. The nimus, Pleurophorus elongatus,
top often covered with Saurichthys apicalis, S. acwmi-
crushed shells. natus, Gyrolepis, Hybodus-spines,

bones, coprolites, ete.; Ichthyo-
saurus, Plestosaurus, Termato-
saurus.

| pia Q Black shales, with ‘ Pul- <Avicula contorta, Axinus, Cardiune

- lasira ’-bands. rheticum.
fe: 0 8 Lower Pecten-Limestone; Pecten valoniensis, Avicula con-
shaly on the top, full of torta, Axinus cloacinus, A. con-
Pecten. Locally very centricus, Cardium rheticum,
pyritous. C. cloacinum, Gervillia precursor,

Modiola minima, Myacites striato-
granulata, Anatina, Anomia ;
Gyrolepis Alberti.

es) «A QO Black shales, with arena- Fish-scales; the arenaceous bands
ceous bands. contain ‘ Pullastra,’
(15a. The upper part of this is hard, fissile ‘Paper-Shale,’ very

barren, 16 inches thick.)
14. 0 1to6 Bone-Bed.
(13-1.) (See Etheridge’s paper, op. supra cit.)

In addition to the fish-remains enumerated above, the Plewro-
phorus-bands (18), which are very abundant on the beach, yield
numerous rounded quartz-pebbles, varying in size up to half an inch.
There are no other pebbles, and the general grain of the bed is fine.
These will be referred to later (p. 182).

The discovery of Estheria and Nazadita is interesting, as linking
Aust with other Rhetic exposures, notably that of Westbury-on-
Severn. These fossils are by no means common, but I have
obtained several specimens of each.

Ill. Tur Puystcan GrocRaAPHy oF THE Ramric PERIOD.

(A) An Account of the Constituent Beds, with special
reference to the Conditions of their Deposition.

(a) The infra-Bone-Bed Series.—Some would include here
the Tea-Green Marls, which will be discussed later. But there are
occasionally Rhetic strata below the Bone-Bed. As will be seen in
the next section, by the Bone-Bed I mean a layer low down in
the Black Shales containing bones, teeth, and pebbles or rolled
marl, thus distinguishing it from other layers rich in teeth.

At Watchet the infra-Bone-Bed Series is fossiliferous (6). At
Redland, and at Stanton-on-the-Wolds (31), Black Shales lie
beneath the Bone-Bed.

(6) The Bone-Bed.—This is one of the most characteristic of the
constituents of the Rhetic Series, not only in England but also in
Germany, France, etc. Yet, despite its wide distribution, from
Gainsborough (12), and Nottingham (31), through Penarth, Aust,
Watchet, and Bristol to the Mendips at Emborough (48), and thence

nw 2

180 MR. A. RENDLE SHORT ON RHZTIC [| May 1904,

to the Continent, it is often absent at intermediate places, as at
Droitwich (27), Stoke Gifford, and locally at Aust and Penarth.
The conditions, therefore, to which it is due, were operative over a
wide area, but only in certain parts of that area.

An interesting feature is the frequency with which the Bone-Bed
occurs in pockets on a flat surface, or spread out over that surface.
I have already described its occurrence in this way spread out on,
and closely cemented to, a planed-off surface of upturned Carbon-
iferous-Limestone bands at Redland (Bristol). At Penarth I found
it lying in pockets on a surface of hard, tea-green, calcareous marl-
stone, which has been worn into irregular hollows and ridges in a
way that suggests contemporaneous erosion. Here it contains,
besides teeth and scales, fragments of rolled marl, more or less
rounded pebbles of Carboniferous Limestone (sometimes as much
as 2 inches in diameter), pebbles of quartzite up to 1 inch in
diameter, and small well-rounded quartz, occasionally black on
fracture. The organic remains are not often entire, unless quite
small; the larger fossils have usually been brokenup. This deposit
has also been noted by Storrie (32). At Chipping Sodbury, again,
the Bone-Bed occurs in pockets in a surface of Carboniferous-Lime-
stone bands that have been upturned and cut off flat, and here also
I found pebbles of Carboniferous Limestone embedded in the Bone-
Bed. There are, as well as these, smaller pebbles of hard sandstone
from the arenaceous bands in the Upper Limestone Series, which are
exposed quite near.

It is well known that at Aust, too, the Bone-Bed includes rolled
pebbles of marl, etc. The true Emborough Bone-Bed, described by
Profs. Lloyd Morgan & Reynolds (48) under (e¢), contains more
pebbles than teeth; it is a closely-packed, rather loosely-cemented
conglomerate full of pebbles, usually about the size of a pea, chiefly
consisting of rolled Carboniferous Limestone, but also of chert and
quartz.

Pebbles are also recorded in the Bone-Bed at Garden Cliff, where
I take it that the lower, though less conspicuous band, is the
true Bone-Bed, and at Bourne Park (54). They are often men-
tioned in Continental records also, as, for example, in Lorraine, at
Hildesheim, etc. (62).

The conglomeratic nature of the Bone- Bed, however, has frequently
been noticed, and further examples are not necessary.

In the Bone-Bed certain fishes tend to preponderate locally. At
Aust it is Ceratodus that, although not now abundant, is yet the
prominent feature. At Redland, Acrodus minimus is most abun-
dant, though Sawrichthys and G'yrolepis follow closely. At Chipping
Sodbury it is Saurichthys, and at Penarth Spherodus minimus
that is most prominent. Ceratodus is fairly common at Chipping
Sodbury.

Now, we may ask, what were the conditions under which the
Bone-Bed was laid down?

I. They must have been conditions of extensive and shallow
water, or of flats just above water-level. This is proved by

Vol. 60. | SECTIONS IN THE BRISTOL DISTRICT, 181

the wide distribution of the conglomerates. It was not
along a beach or shore-line that these beds were deposited: that is
to say, they do not form a narrow band between a shore of older
formations and a deep Rheetic sea, for they do not occur along any
single line. Nothing is more striking than the widespread character
of the deposit. Then, again, at Penarth and elsewhere the Bone-Bed
lies in pockets of a contemporaneously-eroded surface of hard, tea-
green, calcareous marl. In many localities that marl was firm
enough to be rolled into balls. Lee noticed ‘rills on the Marl’ at
Gold Cliff (35). At Lavernock Point the Bone-Bed fills sun-cracks
in the marl (35): here, then, must have been extensive sun-dried
flats, which were overflowed by the sea that laid down the Bone-
Bed. There are ripple-marks in it at Wainlode Cliff (54). From
this facies there is every gradation to that in which no con-
glomerate at all is to be found, but only a few scales and teeth,
or not even that. Here, of course, the water was somewhat deeper,
perhaps several fathoms: probably these deeper parts were of the
nature of channels and pools.

I conclude, then, that at the time when the Rhetic Bone-Bed
was laid down, the great Keuper lake had been nearly dried up in
some localities, or silted up in others. The shallower parts had
been left as muddy flats a few inches above water-level, the deeper
parts as very shallow and extensive lagoons, of course highly saline,
and connecting these were occasional deeper channels or pools.
The exposed flats were rippled and sun-cracked. Then the sea
entered from the German area, and along certain of the channels a
Rheetic fauna spread.

IJ. At a period when the conditions were such as those just
described, and shortly after the Rhetic sea had entered, but before
it had done more than freshen and send its fauna into some of the
main channels, into a set of which it had gained access, came a
period of rough weather.

The points in favour of regarding the Rhetic Bone-Bed as a
storm-deposit are as follows :—

It was not due to the first inrush of the Rheetic sea, for that had
already entered.

It was due to a cause operative over the whole of England, and,
probably at the same time, ‘over part of the Continent.

It resulted in the overflowing of dry flats a little above water-
level.

The movements were such as to scatter pebbles, roll fragments of
marl, break bones and teeth that were large, and often round off
the smaller ones.

For some reason the cause that determined this conglomerate-
bed also determined the death of immense numbers of fishes, their
disintegration, and the scattering of their remains far and wide.
But in certain localities, presumably where the water was deeper,
these results did not take place, consequently the fishes were not
killed, and the water at the bottom was not so disturbed as to
lay down a conglomerate.

1382 MR. A. RENDLE SHORT ON RHZTIC [May 1904,

An interesting modern analogy has been described by Leith
Adams.’ In September 1867 a violent storm killed such numbers
of fishes in the Bay of Fundy, by driving them into shallow water,
that the coast was in places covered with their bodies to the depth
of a foot.

Raised by the storm, the waters overflowed most of or all the
mud-flats, scattering pebbles from the Carboniferous Limestone
and other beaches of the old Keuper lake. These pebbles had, of
course, been rounded long before on the beaches, and the storm
merely spread them out over the flats.

We may here notice the abundance of small rounded quartz-pebbles
that are often recorded in the Bone-Bed. I have found them at
Redland, Aust, Chipping Sodbury, Penarth, Emborough, etc., and
they frequently occur elsewhere. ‘They are often observed far away
from any quartziferous rocks, apart from any other siliceous pebbles.
They are seldom more than half an inch in diameter, and are
usually smaller, but are seldom smaller than hemp-seed. They are
fairly well-rounded as a rule, and if angular the sharp edges have
always been just blunted. They usually have a peculiar resinous
appearance,

These quartz-pebbles frequently occur under similar conditions
in Germany, and were thought by ‘Quenstedt (56) to have been
swallowed by Jchthyosaurus and other vertebrates for digestive
purposes. My attention was first called to this hypothesis by Mr.
A. Vaughan. Quenstedt succeeded in demonstrating them in the
position of the stomach, inside an Jchthyosaurus-skeleton. Such an
explanation fits in well with their peculiar distribution, referred to
above. The characteristic surface and the rounding-off of the edges
would be very likely under such circumstances. But the most
important proof of the theory, to my mind, was furnished when I
noticed their abundance on the surface of the argillaceous limestone
numbered 18 at Aust, which is covered with Pleurophorus elongatus,
fish-remains often large, slender and yet perfect, coprolites, and
these quartz-pebbles, but no others (see p. 179). The bed is not in
the least conglomeratic—in fact is fine-grained, and nevertheless
these pebbles, of this particular description only, are found with
the fish-remains on the surface. They cannot possibly have been
washed there by water; they must have been dropped.

I need scarcely say that all the pebbles in the Bone-Bed did not
have such an origin. Angular pebbles of limestone are frequent,
which could never have survived a passage through an animal's
alimentary canal. Moreover, the Carboniferous-Limestone and
siliceous-grit and marl-pebbles are generally much bigger, and more
irregular in size and shape, than the quartz-pebbles ever are.

(c) The Black Shales.—These are very constant, and too well
known to need description.

In the Bristol district there is always a zone of very firm, well-

1 Quart. Journ. Geol. Soe. vol. xxix (1873) p. 8038.

Vol. 60. } SECTIONS IN THE BRISTOL DISTRICT. 183

- laminated black shales near the bottom of the series, well deserving
the name of ‘ Paper-Shales’ when dry. This zone is very barren.

Mr. Parsons has observed, at the base of the Black Shales at Red-
land, a very curious type of passage-beds between these shales and
the underlying beds, which are ‘often yellowish-brown shales or
clays, sometimes typically-green laminated marl. Instead of a bed
of well-marked Black Shale resting upon one of brown or green marl,
the shales of the two series dovetail one into the other, and in one
and the same bed pieces in some parts black, in others green, may be
found. Moreover, it is common to find a horizon chiefly of Black
Shale overlain by one chiefly of green, or red, or yellow shale or marl.
In fact, at the junction every variety of admixture may be noted.
Mr. Parsons explains it by assuming that the whole was originally
black, and has been bleached by oxidation through the agency of
pyrites. Heis even prepared toassume that the whole of the Green
Marls were so produced (47).

Concerning the truth of his observation there is no doubt. But lL
think that a much more probable explanation is that the Black Shales
are simply the brown or green clays with organic matter added.
Just when the Rhetic sea entered and brought this animal life, it
is not at all surprising that it should be patchy in distribution at
first. hen the interlocking would be readily explained. This is
all but proved by a somewhat parallel case. In my description of
the shale just above the Cotham Marble at Redland, numbered QO,
I have mentioned that it is usually yellow, and is barren. But in
one place it becomes fossiliferous, and has yielded Modiola minima,
Monotis decussata, etc. (see p. 174). And here it is no longer yellow,
but black; of exactly the same appearance, in fact, as the Avicula-
contorta shales.

The Black Shales include several inconstant bands of siliceous or
pyritous grit, often marked with the obscure fossil that was for-
merly called ‘ Pullastra. They are somewhat pyritous all through.
Ripple-marks (27) and sun-cracks are recorded (31). Occasionally,
Seams rich in teeth and scales and coprolites occur, which have
been dignified with the name of Bone-Beds, as at Emborough in
the Mendips (48), and at Garden Cliff(2). At Cotham, in the
section that I have described, elytra of beetles probably occur.

What conclusions can we draw from the foregoing observations
as to the physical conditions of deposition of these beds? After
the Bone-Bed storms, the depth of the water evidently increased,
partly due to rains, and partly to depression of the land. The
salinity had now been corrected, and the open communication with
the sea kept up the relative freshness. In fact, the Rhetic Period
in England seems to have been a good deal more rainy than the
Triassic, and the waters ultimately became brackish. During the
Black-Shale time-interval, however, they were probably of ordinary
oceanic salinity. Although deeper than before, the Black-Shale
sea was still shallow, and occasionally patches were left dry to
sun-crack. Rippling and the occurrence of insects also indicate
fairly-shallow water.

184 MR, A. RENDLE SHORT ON RHAHTIC { May 1904,

(2) The Pecten-Limestones.—Just above the Black Shales it
is usual to find one or more seams of very hard, thick, badly-jointed
shelly limestone, usually blue inside and yellowish-brown when
weathered, rich in Pecten valoniensis. There are frequently two
such bands, and occasionally, as at Aust and Watchet (6), three.
Where absent, they are represented by a shale very rich in Pecten
valoniensis, which is also found always in the Black Shale immediately
beneath them. These limestones are not usually ripple-marked or
sun-cracked ; they are probably the relics of an ancient shelly ooze,
deposited in rather deeper water than the rest of the Rhetic. The
transition from shale to limestone is due to the following of a
dry period, with less washing down of mud by the streams, upon a
wet one; and at the same time to the importation of many molluscs,
and very likely minute calcareous organisms as well.

(e) The Naiadita-Beds.—Above the Pecten-Limestones occurs a
series of thinly-bedded limestones and valcareous shales, originaliy
blue when massive, but weathering yellow or grey, containing
Estheria minuta, var. Brodieana, and Naiadita. These beds are
recorded at most of the important Rheetic exposures.

‘hey are seldom very fossiliferous, and are not at all like the
shelly Pecten-Limestones. Nearly all, usually all, their fossils occur
along certain shelly or plant-covered horizons. Otherwise, they are
fine-grained and barren. It is interesting to note how 4stheria,
Naiadita, and the shells (Pecten, Axvinus, Cardium, etc.) tend to
avoid each other’s horizon. I have never seen Hstheria and
Naiadita together; shells and Nazadita only occur in company
occasionally.

Most noticeable about these beds is the abundant and often
striking evidence of shallow-water conditions, or even exposure,
that they commonly afford. At Redland this is excellently shown
by a fine series of ripple-marks, sun-cracks, and worm-tracks. It is
common to find worm-tracks on a rippled surface, in a grey thinly-
bedded marlstone, looking exactly like a modern beach. I have
found specimens of sun-cracked argiilaceous limestone showing
most excellently the fine flaking-off of the top layers of dried mud.
Further evidence of shallow water is given by the frequency of
wings of insects, as, for example, at Stoke Gifford and Redland.
‘These shallow-water conditions prevailed over an extensive area,
not merely along a shore-line. They are well marked at Redland,
Stoke Gifford, Penarth, Watchet, etc.

The chemical composition of these beds is variable. One specimen
from Redland, more calcareous in appearance than most, contained
60 per cent. of carbonate of lime. Others contain less. I found
on microscopical examination only tiny calcite-crystals and shell-
fragments, but no foraminifera. It is true that the examination
was a somewhat imperfect one.

(f) The Clay-Beds.—In practically every British Rheetic
section there is a variable but often considerable thickness of blue,

Vol. 60. | SECTIONS IN THE BRISTOL DISTRICT. 185

yellow, or grey clayey beds above the shaly Nazadita-limestones,
and below the Cotham Marble. Those beds are almost invariably
barren of organic remains.

(7g) The Cotham Marble.—I have discussed the origin of this
rock elsewhere (53), and merely state here that my theory demands a
chemical origin, by precipitation of carbonate of lime, under a hot
sun, in an extensive, very shallow lagoon with occasional deeper
pools.

The Cotham-Marble horizon, when that stone is absent, is usually
represented by white rubbly limestone, or else yellow clay or shales.
Sometimes Chemnitzia nitida and Monotis decussata, the most
characteristic representatives of the Cotham-Marble fauna, occur
in these, as at Pylle Hill (86), where Wilson subsequently found
the Landscape-Stone in his bed N (45).

(hk) The White Lias.—With this may be here included all
the beds between the Cotham Marble and the lowest Ammonites
planorbis or Am. torus.

The White Lias itself usually consists of rubbly, white, cal-
careous beds, with a good deal of siliceous matter. ‘The occurrence
of insects in these shows that they were laid down in shallow
water (1). They are, as a rule, shelly.

Above these, beds exactly like those of the overlying Liassic lime-
stone (that is to say, thinly-bedded, blue shelly limestone weathering
yellow or brownish-yellow, with yellow or brown shaly partings)
generally occur. Sometimes, as at Aust and Stoke Gifford, these
follow immediately upon the Cotham Marble, with at most a shaly
parting, but no rubbly limestone.

Around Bath is sometimes found the stratum, called the Sun-
Bed, which Moore and others take to mark the upper limit of the
Rhetic. It is hard, with conchoidal fracture, very fine-grained,
cream-coloured, blue, or white; the upper surface is corrugated,
and some consider it sun-cracked. It is marked by worm-tubes,
which are very common in the White Lias in some places (as, for
example, at Redland), and contains Modiola minima and Ostrea
hassica. I think that to this bed, which is extremely local, has been
accorded an importance which it does not deserve. Its chief
interest, in conjunction with the occarrence of insect-wings in the
White Lias, is the evidence provided of the persistence of the
shallow-water conditions that prevailed throughout the Rhetic
Period until this time.

(B) A General Account of the Physical Geography of the
Rheetic Period in England.

The most peiportong paper that has appeared on this subject was
by Sir Andrew Ramsay in 1871 (16). He argued that the Keuper
was laid down in a great inland sea, which gradually dried up,

186 MR. A. RENDLE SHORT ON RHATIC [May 1904,

becoming extremely saline, like the Dead Sea to-day. He remarked
(op. cit. p. 196) :—

‘The thin Rhetic beds of North-Western Europe might have been deposited
in great part in shallow seas and in estuaries, or in lagoons, or in occasional
salt-lakes of small or great dimensions, separated from the sea by accidental
changes in physical geography.’

Moore (13) referred to the Rheetics as oceanic, and Etheridge spoke
of Penarth as being in the middle of the Rhetic ocean (17).

Some writers, following a suggestion by Brodie (1), have con-
sidered that the Rheetic Series is estuarine. Now it is, I think,
generally admitted that Ramsay’s theory of the Keuper is correct.
There was a vast lake covering a large part of England, which
gradually evaporated. The conditions were probably desertic.
Therefore over that area there would be a more or less uniformly-
horizontal surface, with perhaps very gently-shelving shores, and
occasional deeper pools and channels. The Triassic lake seems to
have evaporated nearly to dryness, except in the pools and channels
which were a few feet deeper. The evidence of this is to be found
in the minerals—rock-salt, for instance, indicating great concen-
tration—and in the footprints on the Keuper shores.

Thus, before the Rhetic sea entered, the conditions were as
favourable as could be for the deposition of very shallow-water beds
over a very wide area. When matters stood thus, a gradual de-
pression of the land allowed the Rheetic sea from Germany and
France to enter, very gently at first. The channels that it more par-
ticularly entered were freshened, and the Rheetic Series of the infra-
Bone-Bed horizon at Watchet, etc. was laid down, while Black Shales
commenced to form in various places. Then came the storms which
produced the Bone-Bed, and swept the waters over the just uncovered
flats. Probably this storm also broke up the dry weather, and
ushered in a wetter season. Owing to this, and to continuance of the
slight depression, nearly the whole area of the old Keuper lake was
covered by the shallow Rhetic sea. Although most of the Rhetic
has now been removed by denudation, it is nearly always found
where any beds resting upon the Trias have been left; and that not
only along the Jurassic escarpment, but also at Watchet, Penarth,
and near Burton-on-Trent (16). The chief exception is in part of
Lincolnshire, where the Rhetic and Planorbis-zones are said to be
absent (21). Throughout the whole Rheetic Period, the same con-
ditions of extensive very shallow-water conditions, over the entire
Triassic lake, prevailed. There was, of course, communication with
the Alpine and Germanic Ocean to the south. Owing to the pauses
in depression, the sea was in most places nearly silted-up by the
time when the Naiadita-Beds were laid down, and every evidence of
shallow water, and occasional exposure to the air, over wide areas,
has been preserved. The ripple-marks, sun-cracks, and insect-wings,
the paucity of big saurians between the Bone-Bed (which was laid
down by astorm such as still washes whales into shallow water and
breaks them up) and the White Lias—all these tell the same tale.

Slight depression then again occurred, and clays were laid down.
Once again the depression was balanced by silting-up, and the

Vol. 60.1} SECTIONS IN THE BRISTOL DISTRICT. 187

Cotham Marbie was laid down in very shallow water. Only after the
White-Lias period did the water finally become moderately deep.
We may conclude, then, that the Rhetic Series was laid down
in a gigantic shallow lagoon connected with the open
sea to the south.

The waters were probably brackish on the whole, but with great
variations at different times and places. Such extensive sheets of very
shallow water must have been extremely apt to dry up whenever the
sun was hot, especially in isolated pools. It would in these become
very saline; the animal life would die, and rock-salt and gypsum
would be deposited. As Ramsay remarks, the Rhetic Beds do
occasionally and very locally contain gypsum and pseudomorphs
after rock-salt. Around Bristol baryto-celestine is common, which
is here a mixture of sulphates of barium, strontium, and calcium,
and probably results from precipitation in a concentrating lagoon.

On the other hand, in many pools fed rather by streams and rain
than by the open sea, the water would be brackish or even quite
fresh. Prof. T. Rupert Jones claims that Estheria minuta and
Darwinula were fresh- or brackish-water forms. Probably Naiadita
only flourished in fresh or slightly saline-water.

It will be seen from the foregoing remarks that I do not believe
that the Rheetic Beds were laid down in an estuary, and that for the
following reasons :—

(a)—They obviously follow the distribution of the Triassic lake
pretty closely, as they occur at places so far apart as Gainsborough,
Uplyme in Dorset, Watchet, Penarth, Burton-on-Trent, and along
the Jurassic escarpment. It would have been indeed extraordinary
if in so short a time an enormous river had developed, the estuary of
which should correspond so ciosely to the Triassic lake. The shape
of the area over which the various Rhetic exposures are distributed
does not at all suggest an estuary.

(6)—The principal evidences suggesting an estuary in geology
are the abundance of land-plants and animals, and the presence of a
brackish-water fauna. Now, the Rhetic Beds do not display these
at all well. The only certainly land-derived remains are Microlestes,
which is found in the infra-Bone-Bed Series, the wings of insects,
and a few pieces of drift-wood, some of which I have recorded from
Redland. Most of the fossils are not brackish-water, but oceanic.

TV. Tue SrratiGRAPHY oF THE RuzrIc SERIES.

Zoning of the Rhetic Beds in England.

In 1861, Moore, in his classic paper (4), zoned the series between
the Keuper and the Planorbis-beds as follows (op. cit. p. 487) :—
(Planorbis-Beds.)
Enaliosaurian Zone.
White Lias. :
Avicula-contorta Beds. } Reeric,
(Keuper.)

It is curious that no more definite paleontological zones should

188 MR. A. RENDLE SHORT ON RHZTIC [May 1904,

have since been decided on, seeing how well the Jurassic has been
zoned. I would suggest the following :—

( Planorbis-Zone.)

{ Some beds of Blue Lias. )
: | White Lias.
(=Cotham Marble and just above).

- ( = Naiadita-Beds).

Pleuromya-Crowcombeia Zone. ( =

Monotis-decussata Zone.
Naiadita and Estheria-nrinuta, \

var. Brodieana-Zone. J
Pecten-valoniensis Zone. (= Pecten-Beds).
Avicula-contorta Zone. (= Black Shales).
Bone-Bed.

(Keuper.)

Pecten valoniensis is recorded in the Black Shales, and also in the
White Lias. Except those specimens that occur just at the top of
the Black Shales, however, I believe that nearly all the former are
really Cardium cloacinum, which has but lately been recognized in
England by Mr. L. Richardson and Mr. A. Vaughan; and most, if
not all, the White-Lias ferms are probably Pecten dispar (Terquem),
which, however, is not very different (Vaughan).

Naiadita was originally described by Buckman and Brodie as
occurring above the Cotham Marble at Aust, Horfield, etc. in
all the places that they mention it certainly occurs below, and
never (to my knowledge) above the Cotham Marble. Ali later
writers agree in this.

Pleuromya Crowcombeia is not the same as Pteromya Crowcombera
(which is a fossil from the Pecten-Beds). It is very common in
the White Lias and in the lowest beds of the Blue Lias, and
appears to be recorded under the most various names. It becomes
extremely rare when the ammonites begin.

The ranges of Cardium rheticum, Modiola minima, and Ostrea
liassica are too long to allow of their being used for zoning. The
saurians are inconstant.

It is not contended that the zone-fossils are confined to their
own horizon: for example, Monotis decussata is occasionally found
in the Lias; but they are only met with in any abundance there,
and are of very practical service.

(i) With regard to the constancy of these zones throughout
England, I would submit that they are fairly constant, and would
especially refer to the four sections described in this paper, and to
Garden Cliff (54), Wainlode (54), Wood Norton near Evesham (51),
Stratford-on-Avon (2, 20), Watchet (6): here Pecten valoniensis is
recorded below the Bone-Bed—this is unique, and there appears to
be doubt about it, for Etheridge, whose determination it was,
afterwards marks it with a query (17), Camel Hill (13), Notting-
ham (31), Pyle Hill (86), and Penarth (17). The other sections
are less perfect, but there are no difficulties that a fresh search
would not probably remove, as indeed has happened at Garden Cliff,
where Mr. Richardson’s observations bring it better into line than did

Vol. 60. ] SECTIONS IN THE BRISTOL DISTRICT. 189

the older records of Wright (2). Even in the north, the succession
may be fairly-well made out by combining sections at Gainsborough,
Leicester, and Market Weighton, except that Plewromya is recorded
with Monotis decussata above it.

(ii) These zones do not fit in with the oceanic type of the Alps
and Mediterranean—a harmony which, however, could scarcely
have been hoped for. But they receive considerable support from
the German, and less perhaps from the French sections, at any rate
in the lower four members.

Especially well do they harmonize with some German sections
described by Schlénbach (57 & 58), as, for example, at Steinloh and
Salzgitter. Here are recorded, in descending order :—

}. Layer with plant-remains.
c—p. (Fossils not mentioned.)
g. ‘ Upper Bone-Bed’: in which Pecten cloacinus (=P. valoniensis)
and Avicula contorta are described by Quenstedt (56).
7. Black Shales, with Avicula contorta.
s. ‘Lower Bone-Bed,’ conglomeratic.
7. Greenish-grey marl.

V. Summary.

I. Descriptions of sections :

(a) At Redland, distinguished by a bone-bed and an excellent suite of
fossils.

(6) At Stoke Gifford, with an insect-bed, but no bone-bed.

(c) At Cotham Road, with an excellent Black-Shale fauna, and well-
developed Nazadita-Beds.

(dq) At Aust.

Il. The Bone-Bed is a storm-deposit in very shallow water and
over exposed flats.

Ill. The Rheetic Beds of England were laid down in a vast, very
shallow lagoon or bay, and derived their fauna from Germany. _

IV. The English Rhetic presents more affinity for the Jurassic
than the Triassic.

V. The following zones may be recognized :—

1. Zone of Pleuromya Crowcombeia= (es geri Sg
2 4 Monotis decussata=Cotham Marble and just above.

3 X, Estheria minuta var. Brodieana, and Naiadita.

4. % Pecten valoniensis.

5 ,, Avicula contorta=Black Shales and a limestone-bed.
6 a Bone-Bed.

The pleasantest page in this paper is to me the one on which
I now record my sincere and hearty thanks to all those to whose
kindness, consideration, and help I owe so much. Especially am T
grateful to Mr. Arthur Vaughan, F.G.S., for directing my attention
to various memoirs, and for some suggestions as to ‘fossils ; to

190 MR. A. RENDLE SHORT ON RH TIC [May 1904,

Dr. A. Smith Woodward, F.R.S., for examining some of the contents
of the Redland Bone-Bed for me; to Mr. L. Richardson, F.G:S.,
for several interesting communications and references; to my
fellow-student, Mr. James Parsons, F.G.S., whose advice and co-
operation in field-work was of the utmost value to me at the
commencement of my research: and last, but not least, to Prof.
Lloyd Morgan and Prof. 8, H. Reynolds for much kind help.

VI. BrerioGRAaPny.

This does not profess to be by any means an exhaustive biblio-
graphy of the Rhetics. At the same time, I believe, it includes
nearly all the English papers of any great importance bearing
on the subjects that I have discussed. Only a few Continental
authorities have been included: namely, those whom I happen to

uote.
; The bibliography of the Cotham Marble I have collected else-
where.

A.—BritisH LITERATURE.

(1) Bronte, Rev. P. B. 1845. ‘ History ofthe Fossil Insects in the Secondary Rocks
of England’ pp. 51-104.
(2) Wrieut, T. 1860. ‘On the Zone of Avicula eontorta & the Lower Lias of
the South of England’ Quart. Journ. Geol. Soc. vol. xvi, pp. 374-411.
(3) Moors, C. 1860. ‘On the so-called Wealden Beds at Linkstield, & the
Reptiliferous Sandstones of Elgin ’ Ibid. pp. 445-47.
(4) Moore, C. 1861. ‘On the Zones of the Lower Lias & the Avicula-centorta
Zone’ Ibid. vol. xvii, pp. 483-516 & pls. xv—xvi.
(5) Jones, T. R. 1862. ‘A Monograph of the Fossil Estherie’ 'E.minuta &
varieties} Monogr. Palzont. Soc.
(6) Dawkins, W. B. 1864. ‘On the Rhetic Beds & White Lias of Western &
Central Somerset, &c.’ Quart. Journ. Geol. Soc. vol. xx, pp. 396-412.
(7) Wrieut, T. 1864. ‘On the White Lias of Dorsetshire’ Rep. Brit. Assoc.
(Bath) ‘Trans. Sect. p. 75 & Geol. Mag. vol. i, pp. 290-92.
(8) Bristow, H. W. 1864. ‘On the Rhetic (or Penarth) Beds of the Neighbour-
hood of Bristol & the South-West of England’ Rep. Brit. Assoc. (Bath)
Trans. Sect. pp. 50-82.
(9) Tawney, E. B. 1866. ‘On the Western Limit of the Rhetic Beds in South
Wales, & on the Position of the Sutton Stone’ Quart. Journ. Geol. Soc.
vol. xxii, pp. 69-93 & pls. ili-iv.
(10) Duncan, P. M. 1867. ‘On the Madreporaria of the Infra-Lias of South
Wales’ Ibid. vol. xxiii, pp. 12-28.
(11) Bristow, H. W. 1867. ‘On the Lower Lias or Lias-Conglomerate of a Part
ot Glamorganshire ’ Ibid. pp. 199-207.
(12) Burton, F. M. 1867. ‘On the Rhetic Beds near Gainsborough’ Ibid.
pp. 315-22.
(13) Moore, C. 1867. ‘On Abnormal Conditions of Secondary Deposits, &c.’ Ibid.
pp. 459 et seqq.
(14) Stoppart, W. W. 1868. ‘Notes on the Lower Lias-Beds of Bristol’ Jdid.
vol. xxiv, pp. 199-204.
Groom-NapieEr, C. O. 1868. ‘On the Lower Lias-Beds occurring at Cotham.
&c.’ Ibid. pp. 204-205.
(15) [ErHERIDGE, R.] 1868. ‘Notes upon the Rhetic Beds at Aust Cliff, with
relation to those at Westbury-on-Severn’ Proc. Cottesw. Nat. F.C. vol. iv,
pp. 13-18.
(16) Ramsay, A. C. 1871. ‘On the Physical Relations of the New Red Marl,
Rhitic Beds, & Lower Lias’ Quart. Journ. Geol. Soc. vol. xxvii, pp. 189-98,

Vol. 60.] SECTIONS IN THE BRISTOL DISTRICT. 191

(17) Erneripes, R. 1871. ‘On the Physical Structure & Organic Remains of the
Penarth (Rhietic) Beds of Penarth & Lavernock’ Trans. Cardiff Nat. Soc.
vol. iii, pt. ii (1872) pp. 39-64 & pls. 1-11.
(18) Witts, H. 1871. ‘Aust Cliff’ Trans. Clifton Coll. Sci. Soc. pt. iii (1872)
pp. 49-56 & plate.
(19) Jupp, J. W. 1873. ‘TheSecondary Rocks of Scotland’ {The Rhetic ?] Quart.
Journ. Geol. Soc. vol. xxix, pp. 145-49.
(20) Bropre, Rev. P. B. 1874. ‘Notes ona Railway-Section of the Lower Lias &
Rhetics, &c.’ Ibid. vol. xxx, pp. 746-49.
(21) Cross, J. E. 1874. ‘The Geology of North-West Lincolnshire’ Ibid. vol. xxxi
(1875) pp. 115 e¢ seqq.
(22) Harrison, W.J. 1876. ‘ On the Occurrence of the Rhetic Beds in Leicester-
shire’ Ibid. vol. xxxii, pp. 212-17.
(23) Ussner, W. A. E. 1876. ‘On the Triassic Rocks of Somerset & Devon’ Ibid.
pp. 367 et seqq.
(24) Wrieut, T. 1875. [Presidential Address to Sect.C] Rep. Brit. Assoc. (Bristol)
Trans. Sect. pp. 47 et seqq.
(25) Woopwarp, H. B., &c. 1876. ‘ Geology of East Somerset & the Bristol Coal-
fields’ Mem. Geol. Surv. pp. 69-90.
(26) Tarts, R., & Brakes, J. F. 1876. ‘The Yorkshire Lias’ chapt. v, pp. 30-37.
(27) Harrison, W. J. 1877. ‘On the Rhetic Section at Dunhampstead Cutting,
&c.’ Proc. Dudley Geol. Sci. Soc. vol. iil, pp. 115-25 & plates.
(28) Tawney, E. B. 1878. ‘On an Excavation at the Bristol Waterworks Pumping-
Station, Clifton’ Proc. Bristol Nat. Soc. n.s. vol. 11, pp. 179-82.
(29) Davis, J. W. 1881. ‘Notes on the Fish-Remains of the Bone-Bed at Aust’
Quart. Journ. Geol. Soc. vol. xxxvil, pp. 414-25 & pl. xxil.
(30) ErHeripeGr, R. 1882. Presid. Address [Rhetic or Avicula-contorta Beds |
Ibid. vol. xxxviil, Proc. pp. 138-40, &e. -
(31) Witson, E. 1882. ‘The Rhetics of Nottinghamshire’ Ibid. pp. 451-56.
(32) Storriz, J. 1882. ‘The Fossils at Penarth’ Trans. Cardiff Nat. Soc. vol. xiv,
pp. 100-103.
(33) Witson, E., & QuittER, H. E. 1884. ‘The Rhetic Section at Wigston,
Leicestershire’ Geol. Mag. pp. 415-18.
(34) Woopwarp, H.B. 1887. ‘Geology of England & Wales’ 2nd ed. pp. 242-51.
(35) Woopwarp, H. B. 1888. ‘Notes on the Rhetic Beds & Lias of Glamorgan-
shire’ Proc. Geol. Assoc. vol. x (1889) pp. 529-38.
(36) Witson, E. 1891. ‘ Section of the Rhetic Rocks at Pylle Hill (Totterdown) ’
Quart. Journ. Geol. Soc. vol. xlvii, pp. 545-49.
(37) Fox-Srraneways, C. 1892. ‘Jurassic Rocks of Britain’ vol. 1 (Yorkshire)
Mem. Geol. Surv. p. 384.
(38) Fox-Srraneways, C. 1892. ‘Jurassic Rocks of Britain
Mem. Geol. Surv. pp. 25-123.
(39) Woopwarp, H. B. 1893. ‘Jurassic Rocks of Britain’ vol. 11 (Lias of Eng-
land & Wales) Mem. Geol. Surv. pp. 54, 55, &c.
(40) Broprz, Rev. P. B. 1892. ‘Cestraciont & other Fishes in the Green Gritty
Marls, &c.’ Quart. Journ. Geol. Soc. vol. xlix (1893) pp. 171-74.
(41) Tomss, R. F. 1893. ‘New Genus of Madreporaria from the Sutton Stone’
Ibid. pp. 574-78 & pl. xx.
(42) Newton, R. B. 1893. ‘Molluscan Remains in the English Keuper’ Rep.
Brit. Assoc. (Nottingham) p. 770.
(43) Browne, M. 1893-94-96. ‘ Vertebrate Remains from the Rhetic Beds of
Britain’ Ibid. pp. 748-49; (Oxford) pp. 657-58; & ‘Rhetic Bone-Bed
of Aust Cliff, &c.’ Ibid. (Liverpool) pp. 804-805.
(44) Jones, T. R. 1894. ‘On the Rhetic & some Liassic Ostracoda of Britain’
Quart. Journ. Geol. Soc. vol. 1, pp. 156-68 & pl. ix.
(45) Writson, E. 1894. ‘The Rhetic Rocks of Pylle Hill, Bristol’ Proc. Bristol
Nat. Soc. n. s. vol. vil, pp. 213-31.
(46) Wicxrs, W. H. 1899. ‘A Rhetic Section at Redland’ Ibid. vol. ix (1901)
pp. 99-103 & pl. i.
(47) Parsons, J. 1899. ‘ Additional Observations on the Rhetic Beds at Redland ’
Ibid. pp. 104-108.
(48) Morgan, C. Luoyp, & Reynonps, S. H. 1900. ‘Triassic Deposits at

se eee

?

vol. ii (Yorkshire)

(49) Sortas, Iezrna B.J. 1901. ‘Structure & Affinities of the Rhetie Plant
Naiadita’ Quart. Journ. Geol. Soe. vol. lvii, pp. 307-12 & pl. xiii.

192 MR. A. RUNDLE SHORT ON RH-ETIC [May 1904,

(60) Reynoups, 8S. H., & Vauenan, A. 1902. ‘Jurassic Strata cut through by
the South-Wales Direct Line’ Ibid. vol. lviii, pp. 719-52.

(51) Ricuarpson, L. 1903. ‘Two Sections of the Rhetic Rocks in Worcester-
shire’ Geol. Mag. pp. 80-82.

(52)) Vaueuan, A., & Turcuer, J. W. 1903. ‘The Lower Lias of Keynsham’
Proc. Bristol Nat. Soc. n. s. vol. x, pp. 3-54 & plates.

(53) SHort, A. R. 1903. ‘On the Cotham Marble’ Ibid. pp. 135-149.

(54) Ricnarpson, L. 1903. ‘The Rhetic Rocks of North-West Gloucestershire ’
Proc. Cotteswold Nat. F.C. vol. xiv, pp. 127-74 & pl. v.

(In addition to the foregoing, numerous references to Rhetic geology, etc. will be
found in various Geological Survey Memoirs. }

B.—ForE1Gn LITERATURE.

(55) Orpen, A. 1856-58. ‘ Die Jura-Formation Englands, Frankreichs, & des stid-
westlichen Deutschlands’ [§ 1, der Untere Lias].

(56) QuENSTEDT, F. A. 1858. ‘ Der Jura’ pp. 25 et segq. [Vorlaufer des Lias &
Unterer Lias].

(57) ScuLénBacu, A. 1860. ‘Das Bonebed & seine Lage gegen den sogenannten
obern Keupersandstein im Hanndéver’schen’ Neues Jahrb. f. Min. &c.
pp. 513-34 & pl. iv.

(58) Scu~onBacnu, A. 1862. ‘ Beitrag zur genauen Niveau-Bestimmung des auf der
Grenze zwischen Keuper & Lias im Hannoverischen & Braunschweigischen
auftretenden Sandsteins’ Ibid. pp. 146-77 & pl. i.

(59) Dirrmar, A. von. 1864. ‘Die Contorta-Zone:’ ihre Verbreitung & ihre
organischen Einschltsse’ Munich, 8vo.

(60) Brauns, D. 1871. ‘* Der Untere Jura im nordwestlichen Deutschland’ Bruns-
wick, 8vo.

(61) Berrranp, M., & Kiran, W. 1889. ‘Mission d’Andalousie’ [Infralias]
Mém. Sav. Etrang. Acad. Sci. Paris, ser. 2, vol. xxx. pp. 408 & 605.

(62) LappareEnt, A. pE. 1900. ‘Traité de Géologie’ 4th ed. pp. 1053-68 [Etage
rhétien |.

Discussion.

Mr. H. B. Woopwarp complimented the Author on the clear
exposition that he had given of his views. ‘The instances of inter-
calation of grey marl and black shale confirmed other evidence of
the passage between Keuper and Rhetic, but he (the speaker)
doubted whether the Bone-bBed could be regarded as a definite
horizon. Reference might have been made to Edward Forbes’s
view of the formation of the White Lias in an inland sea like the
Caspian, before depression had introduced the open-sea conditions
of the Lias. He did not agree with the Author in linking the zone
of Pleuromya Crowcombera with the White Lias, as that fossil was
characteristic of the basement-portions of the Blue (Lower) Lias
throughout England—specimens which he had collected at Dunball,
near Bridgwater, were identical in all respects with others obtained
by Mr. George Barrow at Northallerton. By taking the basement
portions of the Lower Lias into the Rhetic formation, the Author
had accentuated its Liassic affinities. The White Lias had con-
siderable local importance, as it extended from Bath to Lyme Regis ;
and, as Charles Moore had pointed out, the junction with the Lower
Lias was usually well marked. In the Bristol area and northward
the White Lias appeared to be extensively overlapped, and there was
evidence in places of a remanié bed at the base of the Lower Lias.

Vol. 60. } SECTIONS IN THE BRISTOL DISTRICT. 193

The Rev. J. F. Brake asked whether the Author could give any
more information about the grey beds which yielded Microlestes.
This at least seemed to indicate terrestrial conditions, but the
Bone-Bed was the commencement of the Liassic deposits. This
kind of bed was often the introduction to a new group of strata—
the Rheetic forming the base of the Lower Jurassic, as the Cornbrash
formed the base of the Upper Jurassic. They always contained some
fossils of the older rocks mixed with those of the newer types,
and thus were aggregates; but they could not be called ‘ passage-
beds’, as the change was rapid and both sets of fossils were intro-
duced together.

The AvrHor replied that, although there were several horizons at
which teeth and bones were abundant, there was one well-marked
horizon near the base of the Black Shales, containing pebbles. This
he called the Bone-Bed. Although a Rhetic mammal, Wicrolestes
appeared in the infra-Bone-Bed Series in England, because it could
wander over the land when the Rhetic Era had commenced, a little
earlier, in Germany.

Q.J.G.8. No. 238. O

194 PROF. REYNOLDS AND MR. VAUGHAN ON THE [ May 1904,

15. The Ruzxric Bens of the Sourn-Wates Direcr Line. By Prof.
Stpney Huen Reynotps, M.A., F.G.S., and Arraur VaueHan,
Esq., B.A., B.Se., F.G.S. (Read February 3rd, 1904.)

[Prare XVIII—Fossis. |

Contents.
Page
1, Entroduction..< 2. bose paeecate ade cece aces See ee ee 194
IL.: Description ofthe ‘Exposures. 2.0-5.c022-<2tee snc eee 194
III. Correlation with the Rhetic of Neighbouring Areas ...... 198
TV ...Paleontological: Notes,:; i .21cs..) estas eae eee ee 201

I. Inrropvuction.

THe Rhetic Beds of the South-Wales Direct Line have been
briefly described by the following geologists :—

1. Mr. H. B. Woodward, in the ‘Summary of Progress of the Geological
Survey’ for 1898, p. 191.

2. The Rev. H. H. Winwood, in the Report of the Excursion of the
Geologists’ Association to the new Great Western Railway-line from
Wootton Bassett to Filton, Proc. Geol. Assoc. vol. xvii (1901) p. 148.

3. Mr. A. Strahan describes the Lilliput section in the ‘Summary of Progress

of the Geological Survey ’ for 1902, Appendix V, p. 192.

4. Mr. A. Rendle Short describes the Stoke-Gifford section in a paper read
before the Geological Society on December 16th, 1903, and now published
in the same part of the Quarterly Journal as the present paper.

Il. Description oF tHE EXposvREs.

The Rheetic Beds are finely exposed in the large cutting near
Stoke Gifford; they come on above the Keuper rocks west of the
Carboniferous-Limestone outcrop at Liliput Farm, and an excelient
section occurs resting upon the Carboniferous Limestone, from
Lilliput Bridge as far east as Chipping-Sodbury railway-station.

(a) The Stoke-Gifford Section.

As Mr. Rendle Short informed us that he was engaged on a
detailed examination of the Stoke-Gifford Rhetic, we have con-
fined ourselves to a general account of the section, and have only
included the results of our independent observations in this paper.
Had we omitted all reference to the Stoke-Gifford section, our
account of the Mesozoic strata of the South-Wales Direct Line would
have been rendered incomplete, which seemed to us undesirable.

On the north side of the line, at Stoke-Gifford railway-station,
the following series occurs, underlying the Lower Lias described by
us in a former communication * :—

* Quart. Journ. Geol. Soe. vol. lviii (1902) p. 719.

= *
Vol. 60. | RHETLIC OF THE SOUTH-WALES DIRECY LINE. 195

Corman Magpie Thickness in feet inches.

| Dark-orey pilot six we eget te sy ohne ison ie towseekadee > 1 7
White argillaceous limestone: ostracods, Estheria,
TELS MB Datel ch: Oh i ee eee ee 0 a
| Deere Bite ee ns es es aay! os, ean sen o 0
White argillaceous limestone, with variable shaly
i partings and lenticular beds of hard gritty lime-
stone. Estheria minuta var. Brodieana is
| common in the white limestone ..........5....... + 0
( (ii) Black shale, often very papery. Pecten valoni-
ensis, Car dium rheticum, and Schizodus
| Ewaldi ave abundant, Avicula contorta rare :
! with them occur bands full of fish-scales,
TEPC hiy BI: WORE DEE 7 eo ons oe vnc cence eee wen «<2 6 Q
(i) Hard, black, compact limestone, sometimes
| pyritous. Pecten valoniensis and Cardiwin

Urrrer Ruetic.

Lower Ruatic
——— A
ee
—_
es

rheticum are abundant......00....s000-esesene-s 4 0
II & I. Shales ete. not well exposed for examination. -————_
(Grey or Tea-Green Marl.) 18 10

At the western end of the south side of the very wide cutting
at Stoke Gifford, the Upper (but not the Lower) Beds of the Rhetic
Series are exposed. The series is somewhat thicker than that on
the north side of the line, as is seen from the following section,
the beds on the two sides being numbered in correspondence :—

Goin Mansix Thickness in feet inches,

ERE UCM SIGNED ins eho Bet cack oe tapkrs ides bee 3 8
ieee WY bite areillaceous limestone “<2. 20.2. .2cse62 6 se 25-00 en Oy 5
| DN Gge ee POE, SRNL cei asi, iss ced essa cos lec Seaap Paes penis 4 6
IV. Thinly-bedded argillaceous limestone, with Naiadita. 2 0
1 Palo:shale to base of section, 6.0.5.chs-ivececes sesvedoosese 0 6 seen
ir | Pecten-bed, shown in a drainage-cutting at the base of
| the slope.

The most noteworthy feature of this section, as compared with
that (which will be described on p. 197) lying to the east of Lilliput,
is the complete absence of the Bone-Bed.

(6) The Lilliput or Chipping-Sodbury Section.

A section of the Rhetic occurs, overlying the Keuper, at the end
of the Carboniferous-Limestone section west of Lilliput Bridge.
The beds here were, unfortunately, already much overgrown when
we first visited them. The section is as follows :—

Compact limestone (Sun-Bed), with a somewhat ) Feet inches.
doubtful representative of the Cotham Marble.

[ browntor geoyish shales j¢c..Fevisase cae oc aed suis 2 0
: Pale argillaceous limestone..............sse-s.ssesees 0 5
ey: CFPEV IS ARIE. Nee pena passe Wanden <levesctalena bores 3 0
Argillaceous limestone»: 50.00... pets ceva ce cceecouee 0 7

Darker, more crystalline limestone, with Pecten

Wr 1.1 valoniensis and bands of fibrous carbonate of
ae ee TUNG (SAGE: RE OG «cn cali ere anna sah PeeSihmnmac 0 3
Black, often papery, shale 2.0.0.0... 0resseeen ens 12 0
(Tea-Green Marl.) 18 3

02

la H's

“OJOUE
My ME foe soe

‘uoyns-linayie hungpog-hurddryy fo ;
‘ouorspune yt if urddryg fo ysam
IUOISPUDY PPM PIO 2%? wodn Ajqnu4sofuosun HUrpsat ‘IUMUT au? {0 SaVDUY DI tu =, a

2

Vol. 60. | RHETIC OF TUE SIULH-WALES DIRECT LINE. 197

The thickness of the Rhietic Series here is practically identical
with that at Stoke Gifford, and the correspondence between the
Upper Beds at the two localities is very close. The two sections
agree, too, in the absence of the Bone-Bed.

East of Lilliput Bridge a splendid Rheetic section comes on, and
extends as far as a point to the east of the Old-Red-Sandstone out-
crop lying west of Chipping-Sodbury railway-station. The series
varies a good deal in thickness, being thickest where the Paleozoic
rocks have been much denuded. At two points where large
rounded hummocks of the Paleozoic project into the Rhetic, the
Black Shale is deposited on them in an arched manner, forming an
anticline of bedding. The section is remarkable for the occurrence
of a very rich Bone-Bed at the base, but this is not uniformly distri-
buted. It is first met with as one passes east from Lilliput Bridge
at a point about 150 yards from the bridge : it extends for a distance
of about 130 yards, aud then again disappears, reappearing after
some 200 yards, and extending continuously to the end of the
Paleozoic outcrop.

The Upper Rheetic agrees more closely with that of Stoke
Gittord, and shows less lateral variability than the Lower. A
point 100 yards to the east of the bridge for the road from Kin-.
grove Farm (see fig. 2, p. 198) gave the lei section :—

CotuamM MarsLe. Thickness in feet tnches.
( | Grey shale, containing plant-beds at 15 and at
Shy 18 inches from the top. Darwinula and
= . MM et A Porte a Si. 2nd Devan odedenceweeee 2 o
= Brown unfossiliferous shale ..................0e.00000 1 0
< fe EPIUBECONE IMHESLONG | 5.) 2... cncsenseesseneae 0 6
= | Brown or grey shale, with lenticular beds and con-
=; IV. 4 cretions of argillaceous limestone at two or three
~ | levels. Fragmentary shelis, Cardiui cloacinum
u NN a tate 6 os whine ines dahl nisin siewtaia aul wag anes pe D 0
( - Black shales; with dark caleareous bands: Pecten }
ITl. valoniensis, Cardium rheticum, and C. cloacinum

are very abundant, Avicula contorta rare.
( Black shales, with thin sandy layers: Avicula con-
| torta and Schizodus Ewaldi are very abundant ; |
} Cardium cloacinum and Myophoria postera, + 9 0
} plentiful; Modiola sodburiensis teems in the
| sandy layers; Pecten valoniensis is apparently
| absent.
( Non-fissile black shale, with a rare tooth or vertebra. |
| 8
{
\

it:

Soft black clay, crowded with vertebrates _........ }

Hard Bone- Bed, containing quartz-pebbles Dey

crowded with vertebrates ; Plicatula cloacina

GS; FAN AMMETDMOIN so-so sda dan be vesh a ge nctavice 0 3

i:

Lower Rivaric. *
Se ae Sy ee hs ee a

The foregoing constitutes a typical section of the Sodbury Rheetic :
but the beds show considerable lateral variability, lenticular hard
bands sometimes of a gritty nature, though generally of limestone,
appearing at various levels in the Black-Shale Series.

E.

_ Near
Chipping Sodbury
Station

Bridge
from Kingrove Farm

is 2,

Lilliput Bridge

ue - III. Correiation WITH THE
Ke Ryxtic or NEIGHBOURING
35 Se AREAS.
yee) ue

S& The earliest local Rhetic
os pS section to be described with
ag ~ sufficient detail was that at
Fe Pyile Hill (Bristol), by the late
z S Edward Wilson,’ and within

the last few years a number
of Rheetic exposures in North-
West Gloucestershire * (includ-
ing the important sections at
Wainlode Chiff and Garden
Cliff) have been examined or
re-examined, with equal care
and wealth of detail, by Mr.
Linsdall Richardson. A _ sec-
tion at Redland (Bristol) has
been carefully described by
Mr. W. H. Wickes*; while,
quite recently, Mr. A. Rendle
Short has undertaken the
minute re-examination of this
section, as well as of the Stoke-
Gifford cutting and of Aust
Cliff. Since, however, at the
time of writing Mr. Short’s
paper is not yet published, and
Mr. Wickes has himself cor-
related the Redland section
with that at Pylle Hill, it is
only necessary for us to point
out the correspondence of
the Rheetic sections on the
South-Wales Direct Line with
those described by the late
Edward Wilson and Mr. L.
Richardson.

Taking account merely of
the main features, all the local
Rhetic sections exhibit the fol-
lowing general sequence :

pal Lias

Section from Lilliput Bridge to near Chipping Sodbury Station, (?/4”2/0/s-beds)

Upper Rhetics
75 feet.

OTL

= 300 feet; Vertical scale:- I inch

Horizontal scale:- Iinch

Outcrop of
Bone Bed

1 «On a Section of the Rhetic
Rocks at Pylle Hill (Totterdown),
Bristol’ Quart. Journ. Geol. Soe.
vol, xlvii (1891) p. 545.

2 «The Rhetie Rocks of North-
West Gloucestershire’ Proc.Cottesw.
Nat. F.C. vol. xiv (1903) p. 127.

3 ¢ A Rheetic Section at Redland’

NO on Proe. Bristol Nat. Soc. vol. 1x, pt. il
RAD SS (1899) p. 99: issued in 1901.

Vol. 60. ] RH-ETIC OF THE SOUTH-WALFS DIRECT LINE. 199

Cotuim MarB ez (or its equivalent).

V. Shales, with usually a thin limestone-band containing ostracods
(Darwinula) and not infrequently H'stheria and insects.

Uprrr
Ruaric.

IV. Shales and argillaceous limestone (usually nodular or concretionary)
containing the maximum of Hstheria minuta, var. Brodieana.

This is the horizon at which Naiadita is abundant.

(ill. Dark shales (usually with one or more very hard beds of dark
| limestone), containing the maximum of Pecten valoniensis.
'

8 S II. Black sbale (with occasional thin sandy bands), containing the
ER 4 maximum of Avicula contorta, and probably also of Schizodus
63 | Ewaldi and Myophoria postera,
| 1. Non-fissile black shale, with few fossils. Beds poor in mollusca,
u

but frequently teeming with vertebrate remains.

The notation here adopted may be approximately correlated with
that employed by the late Edward Wilson and Mr. L. Richardson,
as follows :— |

V includes beds in the neighbourhood of 1 of Richardson and im of Wilson.

iv 55 43 ee 3 of Richardson and /: of Wilson.

Ill - A 4 7 of Richardson and g of Wilson.
15 i 34 x 8to12 of Richardson andd of Wilson.
fi Se px He 15 of Richardson and a of Wilson.

A closer correlation seems neither practicable nor desirable, and
all attempts made to find the exact equivalent in a distant locality
of each thin hard layer appears to us, from the very nature of the
deposits, to be doomed to certain failure.

If, instead of considering maxima, we regard entire ranges, it
would be impossible to maintain even the small number of divisions
that we have adopted in this paper. For example:—

Ostracods are found throughout LV as well as in Y.

Estherie are found in V as well as in LY.

Pecten valoniensis is found quite commonly in most localities
associated with Avicula contorta and Schizodus Ewaldi: in fact, the
Lilliput section is almost unique in the rarity with which this
association takes place (for example, at Pylle Hill Pecten valoniensis
and Avicula contorta co-occur in 4, that is, at the bottom of IL;
while Pecten valoniensis and Schizodus Ewald: co-occur in 7, that
is, at the bottom of LV). The vertebrates occur throughout the
entire Lower Rheetic, and even extend into the Upper Series (for
instance, in 2 at’ Pylle Hill); while in certain sections it is almost
impossible to fix even the position of tfeir maximum.

Unfortunately, it has not been the general practice to estimate
the maximum of a species, but merely to register its occurrence in
each bed without any remark on its relative abundance. For this
reason, the comparison of the various sections loses a great part of
its value; for a straggler which has escaped notice at oue section

200 PROF, REYNOLDS AND MR, VAUGHAN ON THE | May 1904,
may have been recorded at another, and given a weight equal to that
of the commonest fossil at the horizon. In this way a completely-
deceptive difference between the two sections is falsely suggested.
Bearing this fruitful source of error in mind, the appended table
may be considered to render as exact an account as is possible
of the range of the best-known Rheetic mollusca at those sections
within the Bristol and Gloucestershire areas which have been most

exhaustively described.

TaBLe I.—Comparison oF THE RANGES oF THE TYPICAL Ruxetic Mouuvusca.

I II Il eae
( to f) (gh) (i,k, D (m)
_| Pyle Hill.

| __.....Wainlode Cliff.

Avicula contorta...

{
Jee
Pecten valoniensis

at

Schizodus Ewaldi 4

Cardiun rheticun
& C. cloacinuin...

Garden Cliff.'
S. Wales Line.

Pylle Hill.
Wainlode Cliff.
Garden Cliff.
S. Wales Line.

Pylle Hill.
Wainlode Cliff.
Garden Cliff.
S. Wales Line.

Pylle Hill.
Wainlode Cliff.
Garden Cliff.

S. Wales Line.

That the information conveyed by the above table may be as

exact as possible, the following remarks seem necessary :—

Avicula contorta.—As a general rule, the determination of this
fossil is possible, even from very small fragments, on account
of its entire dissimilarity from the associated mollusca; but in
I, where Plicatula cloacina is not uncommon, the determination
is rendered more difficult (see p. 203).

Pecten valoniensis.—The determination of this fossil by an accurate
observer may be unhesitatingly accepted.

' We have ventured to dissent somewhat from Mr. Richardson’s correlation
of the beds at Garden Cliff. Seeing that Avicula contorta and Schizodus occur
plentifully below his Bone-Bed (Bed 14), it does not appear to us that this bed
can be considered to be on the same horizon as that at Sodbury, which is well
below the level at which these mollusca commence to occur in any abundance.
It seems more probable that the section at Garden Cliff is one of thé numerous
instances which illustrate the great variability of the position of the Bone-Bed.

Vol. 60. | RHZETIC OF THE SOUTH-WALES DIRECT LINE. 201

| Schizodus Ewaldi.— Wherever the species is stated we have accepted
the determination as correct ; we are somewhat doubtful as to
the value of the information where the genus alone is cited,
and are still more dubious in regard to forms entitled ‘ Pullastra’
(Schizodus).

Cardium rheticum and C. cloacinum (? = Cardium sp. of Wilson).
—These species seem, to a certain extent, to replace each other
in relative abundance at different localities. They are, there-
fore, best treated together, a course which also eliminates
errors of determination.

IV. PatzxontoLoercat Nores. .
(a) Invertebrata (Mollusca). By A. V.

The numerical references in parentheses, throughout the notes

on the invertebrata, are to the following authors :—

(1) Moore, C.—Quart. Journ. Geol. Soc. vol. xvii (1861) p. 483 & pls. xv—xvi.

(2) Quensrepr, F. A.—‘ Der Jura’ 1858, pl. 1.

(3) Dumortier, E.—‘ Les Dépots jurassiques du Bassin du Rhone: I. Infra-
Lias’ 1864.

(4) Terqvem, O.—‘ L’Etage inférieur de la Formation liasique de Luxembourg
& de Hettange” Mém. Soc. Géol. France, ser. 2, vol. v (1855) p. 219.

(5) Bravys, D.—‘ Der untere Jura’ 1871.

(6) Porriock, J. E.—‘ Report on the Geology of Londonderry, &e.’ 1845.

(7) Go.pruss, A.—* Petrefacta Germanizx ’ 1826-33.

(8) Oppet, A., & Susss, E.—‘ Ueber die muthmasslichen Equivalente der
Kossener Schichten in Schwaben’ Sitzungsber. k. Akad. Wissensch.
Wien, vol. xxi (1856) pp. 544 et seqg. & pls. i-ii.

Anomia sp. (Pl. XVIII, fig. 1.)

Upper valve.—Dimensions : vertical=25 millimetres ; hori-
zontal=25 mm. (estimated).

Contour orbicular, with short, nearly straight hinge-line and
small, slightly-projecting beak ; convexity greatest near the beak.

Shell extremely thin and minutely puckered, with strong con-
centric wrinkles.

Lower valve unknown.

Since the only specimen that I have seen is this imperfect upper
valve, it seems advisable to await more material before assigning a
specific name.

The shell-structure is similar to that of Placunopsis alpina,
Winkler, as figured by Moore (1) in his pl. xvi, figs. 4-5, and the
dimensional ratio is about the same; but in our specimen the
concentric wrinkles are much stronger and the beak and hinge-line
different.

Our species differs entirely from <Anomia (?) figured by Quen-
stedt (2), in which the transversity is even more marked in the
young than in the adult (the first growth-line in Quenstedt’s figure
has a transversity of 3, whilst in our specimen the young form is
elongated).

The specimen was obtained from the main <dAvicula-horizon at
Sodbury.

202 PROF, REYNOLDS AND MR. VAUGHAN ON THE { May 1904,

PLICATULA CLOACINA, sp. nov. (Text-fig. 3 & Pl. XVIII, fig. 5.)

Upper valve.—tLargest dimension about
Fig. 3.— Diagram of 20 millimetres.

Pheatula cloacina, Valve strongly convex, narrowing to-
sp. nov., constructed wards the beak.

trom numerous Shell thin, and composed of slightly-

Fragments. overlapping, concentric bands which have

free ragged edges. Fine, sharp, radial ribs
cross these bands at irregular intervals, and
end on the free edges in projecting points.
The outermost bands are ornamented with
fine, close, parallel, concentric, rounded
strie. To the left of the valve, the radial
ribs and spines are much more numerous
and strongly marked, several of the ribs
are continuous, and the spines closely
packed, short, and tubular.

Lower valve very imperfectly known.
[Magnified 2 diameters.) . The specimens all occur in the Bone-

Bed (hence the specific name),

-

LIMA VALONIENSIS.

Fragmentary and crushed specimens are not uncommon at the
main /ecten-horizon.

Prcren VALONIENSIS, Defr. (Pl. XVIII, figs. 2 & 2a.)

The general characters of this species are :—

The byssus-valve is flat, with a narrow beak-angle (80° to 85°),
and ribs usually in pairs. The larger valve is convex, with a broader
convex beak (beak-angle about 100°), and ribs more equal, but
usually containing a few intercalated shorter ones. Concentric
lines of growth not forming erect scales on the ribs.

The most striking characters are: the transversity of the valves,
and the absence of symmetry, characters which are especiaily marked
in the convex valve.

This species was excellently figured by Dumortier (3) in his pls. ix
& x. Under the name of Pecten cloacinus, Quenstedt (2) gave two
figures, both of the convex valve. Both figures illustrate the trans-
versity of the species, but the larger figure is more symmetrical than
is usually the case, and the left wing seems to be erroneously drawn.

A maximum in the upper part of the Lower Rhetic (111): see
p. 200.

AvicuLa conrorta, Portlock (6) [inciuding dAviewla solitaria,
Moore (1)}.

Of the special characters shown by our specimens, we may note
the following :—The anterior convex portion of the large valve is
almost smooth, and this smoothness extends to some distance round
the lower margin in big specimens. Small specimens exactly

Vol. 60. ] RH-ETIC OF THE SOUTH-WALES DIRECT LINE. 203

- resemble J. solitaria, Moore, in the absence of intercalation ; but, in
all adult forms, intermediate ribs make their appearance.

Fragments of shell are found in the Bone-Bed, which exhibit the
characteristic ribbing of Avicula contorta ; but, since they occur in
close juxtaposition to fragments of the Plicatula described on p. 202,
it is a little doubtful whether they may not be small portions of the
more strongly-and continuously-ribbed part of that shell. The weight
of evidence seems, however, against this view, as 1 have never seen,
on any specimen of the Plicatu/a, any ribs which run for so long a
distance without forming spines. Hence we may say that Avicula
contorta extends downward into the Bone-Bed. Upward it occurs,
very rarely, just beneath the Estheria-bed.

AvicuLa FALLaXx, Pfliicker= Vonotis decussata, auctt. [non Munster,

Jide Brauns (5) |}.

We have found one or two specimens, as already noted, in the
uppermost beds.

Mopiors sopsuriensis, sp. nov. (Pl. XVIII, figs. 3 & 3a.)

The largest dimension varies from 5 up to 19 millimetres.

The shell is extremely thin; both valves are exactly similar; in
the young form the valves are strongly convex, but in the adult
they become flatter.

‘The beaks are close to the front end, and there is a slight indenta-
tion just in front of them. Behind the beaks the hinge-line
ascends straight and obliquely, and the valves are broadest where
the straight hinge-line merges into the posterior curvature.

The front margin is uniformly rounded, and only projects slightly
in front of the beak. The posterior margin is also uniformly
rounded, though in adult forms it projects slightly more near the
base. The lower margin is always convex, but becomes nearly flat
in the adult.

The young form is almost perfectly oval in contour, the beak
small, the hinge-line short, and the interior almost smooth.

In the adult, concentric growth-lines are well-marked, and a few
faint radial striae can be made out. A scarcely-perceptible ridge
runs from the beak, diagonally backward, across the valve, but
there is no distinetly-separated, swollen, anterior portion below it.

The interiors (which are extremely abundant) show no trace of
pallial line, muscular impressions, or teeth.

Figs. 12, 13, 27, & 33 (pars) in pl.i of ‘Der Jura,’ all bear a strong
resemblance to our form, but the peculiarity of the hinge-line is
best expressed in figs. 12 & 27. Of these figures, Quenstedt
(op. cit. pp. 29, 30) remarks that figs. 12 & 13 may belong to the
Lithophagi, and that fig. 27 recalls Astarte obliqua. The absence
of teeth and the thinness of the shell, as well as the straightness
of the hinge-line, remove our species from <Astarte; while the
manner of occurrence prevents its inclusion among the borers.

Abundant in a sandy micaceous bed, near the maximum of
Avicula contorta.

204 PROF, REYNOLDS AND MR. VAUGHAN ON THE [ May 1904,

MoproLa MINIMA, Sow.

Our specimens agree well with Moore’s large figure (1), pl. xv,
fig. 27.

The anterior, upper slope (formed by the hinge-line) is somewhat
shorter than the posterior, and rises at an angle of about 20°; the
posterior slope is nearly straight ; the angle between the two
slopes is about 145°. The greatest breadth occurs at the junction
of the two slopes, and is nearly half the largest dimension. The
lower border is nearly straight. The front end is pointed, but there
is no distinct separation of a lower, anterior, swollen portion.

Specimens are not uncommon throughout the Rheetic.

MyYoPHoRTA PosTERA, Qu. (2).

Especially common at the maximum of Avicula contorta.

CARDINIA CONCINNA, Sow. aff. RE- Fig. 4.—Diagram of Cardinia
éuLsEis, Terg.- (PL XVU, concinna, Sow. (aff. C. regu-
fig. 4, & text-fig. 4.) laris, Terg.).

General contour uniformly
oval; lower border broadly and
uniformly convex; hinge-line
nearly straight, and only slightly
converging. Curvature of an-
terior and postericr borders
nearly equal. Beak not pro-

minent; lunule small. The
growth-lnes form strong con-
centric bands. [Magnified 2 diameters. |

DIMENSIONS IN MILLIMETRES.
Spec. 1. Spec. 2.

Horizcntel “st os Se eee eee omy | 30
Wertical: 2. ssc2¢ 808. aos sacle Ree ee ee he 165
Position~ot heals... 4 eens esc eee 516 fea
Radius of curvature of anterior border ............ 5 5
Radius of curvature of posterior border............ 5 4:5

As Brauns points out (5), p. 338, it is impossible to separate the
species of Cardia on slight changes of form, between which there
is every possible mutation. He has consequently limited the number
of Lower Jurassic species to three, namely: C’. concinna, C. crassi-
uscula, and C. Listeri.

The separation of the elongate, regularly-oval concinna from the
tall triangular Listeri is a matter of the utmost simplicity ; but the
allocation of intermediate forms is extremely difficult, and is usually
almost valueless, as representing nothing more than the individual
weight attached to certain variable characters by a particular
author. For example, Brauns distinguishes C. crasseuscula trom
C’. concinna by the following characters (op. cit. p. 340) :—

eral r v0 MYO
Vol. 60.] RH HTC OF THE SOUTH-WALES DIRECT LINE. 205

C. crassiuscula. C. concinna.
horizontal : a
i sional ratio ( : ES > or less. 2:2 or more.
Dimensiona Saaeaeal 3
pee , ; * {| > cs fl a ] 1 4)
Position of beak (from anterior)... Never less than oe 4 tot of length.

The other characters are the same for both, namely: small and
non-prominent beak, general oval form, rounded anterior margin,
and gently convex lower margin. Be

It is, however, just at our RKhetic forms that the above distine-
tions break down; for, in dimensional ratio and position of beak,
our form might be considered to be either a crassiuscula-like muta-
tion of concinna, or a concinna-like mutation of -crassiuscula. In
fact, any distinction based upon the numerical ratio of dimensions
is contessedly artificial; in our case, these distinctions would
separate the young form (shown by the growth-lines), as a typical
crassiuscula, from the adult form, which approximates to concinna.

It seems best to group our forms broadiy under C. concinna,
which may be considered to connote : elongate oval form, uniformly-
and strongly-convex anterior and posterior margins, and uniformly-
but gently-convex lower margin. ;

The figure which most nearly approaches our form is that of
C. reqularis, Terq. (4), pl. xx, fig. 2. which agrees remarkably well
in all respects, except that the convexity of the anterior margin is
greater (in the figure) than that of the posterior margin.

Specimens are common in the main Avicula-beds.

PrevRopHoRUs ELoNGATUS, Moore (? = Anoplophora postera, Deftner
& Fraas). (Text-fig. 5.)

There is no doubt as to the identity of our fossils with Moore’s
species (1); the general contour, and the fold which runs diagonally
backward, render recognitipn easy. There is, however, more
difficulty as to the genus.

The cast exhibits the following characters :—Upper and lower

margins nearly parallel, but
Fig. 5.—Fleurophorus elonga- slightly diverging backward: a
tus, Moore (magnified 13 prominent anterior muscular im-
diameters ). _ pression, in front of the beak.
. circumscribed by a deep furrow:
a pallial line of continuous curva-
ture, ending in a less prominent
posterior muscular impression; a
very blunt beak-region; a sharp
indentation, in front of the beak.
continuous with the deep groove
which forms the hinder boundary
of the anterior muscular impression. All these characters of the
cast, except the blunt beak-region, would apply to any one of the
genera Pleurophorus, Anoplophora, or Myoconcha.

Since Anoplophora has no teeth, and MV yoconcha only a long ridge-

like tooth, running backward from the beak close along the hinge-

. are ry. eI yy
AND STOKE GIFrORD.

ric Mounusca at SopBury

Nd
VI

‘OmMMONEST RIL

ANGE-DIAGRAM OF TIE

3 LL.—

TABLI

Lina valontens 25s.

Modiola

\IModiola so\dburiensts.

Plejurophorwus |-elongatus.

PERS ee

Calirdium ‘rheticum & C. cloacinum.

Schizodus

Pecten vailo

Avicu la

Vv
LN;
TT

minima.

tutla elo\aetna.

Huwaildt.

NMLENSTIS.

contor|ta.

Vol. 60. | RH_ETIC OF THE SOUTH-WALES DIRECT LINE. © 207

line, the cast of a specimen of either genus shows a sharply-pointed
beak.

On the other hand, Plewrophorus had a large hinge-plate, bearing
strong cardinal teeth, so that the cast should be broad and blunt
beneath the beak (as in casts of Cardinia, so common in the Lower
Lias). There seems, then, to be little doubt that Moore correctly
diagnosed the genus. Quenstedt (‘ Der Jura’ pl. 1, fig. 32) figures
a somewhat similar form, but the upper and lower borders con-
verge backward : it can, therefore, scarcely be considered as identical
with our specimen. Brauns (5) unhesitatingly refers Quenstedt’s
figure to Anoplophora postera, and only doubtfully includes Moore’s
species as a synonym. It seems, therefore, very uncertain whether
we have found the species that is so common in the bottom beds
in Germany.

Our specimen was derived from the main Avicula-beds.

CarbDium cLoactnum, Qu. (Text-fig. 6.)

Average dimensions : horizontal, 144 millimetres; vertical, 13 mm.
The largest specimen that we found measured 22! mm., vertically.

Fig. 6.—Cardium cloacinum, Qu. (magnified 33 diameters).

In the fact that the curvature of the ribs is concave towards the
front, and that they increase in breadth towards the posterior margin,
the shell has a somewhat Cardita-like aspect. But the beaks are
scarcely, if at all, turned towards the front, and the teeth are of the
typical Cardiwm-pattern. There is considerable variability in the
number and breadth of the ribs, as well as in the transversity and
convexity of the valves, :

The ribs are broad and, apparently, flat-topped, separated only
by linear grooves (exactly after the pattern of the radial ribs seen

208 PROF. REYNOLDS AND MR. VAUGHAN ON THE [| May 1904,

in Cardium rheticum). The concentric growth-lines are also well-
marked, and produce, in crossing the ribs, the facetted type of
ornament; a few of the growth-lines are much stronger than the
others (producing the frill-type of ornament).

The species is figured by Quenstedt (2), and by Oppel & Suess (8).
It seems impossible to include this form under Cardita Hebert,
Terq., as has been done by Brauns (5), pp. 326-27.

This is the commonest species at Sodbury, and ranges from the
base of the Avicula-bed up into the Hstheria-bed.

Carpium RwzTICUM, Merian.

The specimens are usually large (22 millimetres along the first
radial rib).

The hinder part of the valve is bent along a radial fold, and the
area thus formed is concave ; but there is never a ridge at the fold.
There are three or four ribs in front of the fold. The ribs are broad
and flat, and are separated by linear grooves.

Very common in the main Pecten-bed.

Scuizopus Ewatpt, Bornemann (= Awinus cloacinus, Moore).

‘specially common in the main Avicula-bed.

(6) Vertebrata, with Notes on the Position of the Bone-Bed.
ys: tise.

The vertebrate fauna of the Rheetic Bone-Bed of the Chipping-
Sodbury section is rich and varied, nearly as rich as that of Aust,
which it much resembles. The following species were met with,
the nomenclature adopted being that of Dr. Smith Woodward &
Mr. Sherborn.’

Reprint.

Plesiosaurus costatus, Owen.—'Teeth and vertebral centra occur
occasionally, but are not so plentiful as at Aust.

Rysosteus Owent, Owen.—Small, presumably reptilian, vertebrie
with the characters to which Owen applied the above name are not
uncommon. Mr. Montagu Browne * notes that, in certain respects,
these vertebree have amphibian affinities.

Coprolites and broken undeterminable bones are very common.

AMPHIBIA.

? Metoposaurus diagnosticus, Meyer.—This species, which is well-
known from Aust, might be expected to occur at Sodbury, but its
occurrence can hardly be said to be clearly established. <A

1 «Catalogue of British Fossil Vertebrata’ 1890.
> Rep. Brit. Assoc. 1894 (Oxford) p. 658.

Vol. 60. | RHZTIC OF THE SOUTH-WALES DIRECT LINE. 209

fragment of bone belonging to Mr. W. H. Wickes (to whom we
are greatly indebted for the opportunity of examining a large
collection of Rhetic Bone-Bed material from Sodbury) shows the
peculiar pustulated surface seen in a fragment of bone figured
by Meyer & Plieninger' as part of the breast-bone of a laby-
rinthodont, and also in many fragments of bone of undoubtedly-
labyrinthodont origin in the British Museum (Natural History)
and elsewhere. But, on the other hand, this character occurs in
bones labelled Hybodus in the Stuttgart collection, and in a jaw
of Saurichthys figured by Dr. Smith Woodward.” In connection
with the latter specimen, attention may be drawn to Mr. Mon-
tagu Browne’s suggestion,’ that jaws bearing teeth of two kinds,
which have been described as Saurichthys, may really belong to
labyrinthodonts.
PIscEs.
Elasmobranchii.

Hybodus cloacinus, Quenstedt.—Tecth agreeing closely with
Quenstedt’s figure* occur somewhat sparingly. The large fin-
spines, described by Mr. J. W. Davis’ under the name of Hybodus
austiensis, are fairly common, though always in a fragmentary state
and generally much rubbed. We follow Dr. Smith Woodward &
Mr. Sherborn in considering that they are best provisionally referred
to Hybodus cloacinus. Mr. W. H. Wickes obtained an example of
the curious cephalic dermal spines of Hybodus, described by
Agassiz® under the name of Sphenonchus.

Hybodus minor, Ag.—One small tooth, with a high, slender,
median cone, is probably to be referred to this species.

Acrodus minimus, Ag.—The teeth of a small species of Acrodus
occur in thousands, but always detached. They and the teeth of
Saurichthys are the two commonest fossils in the Bone-Bed at
Sodbury, just as they are at Aust and probably all the other
Rhetic Bone-Bed localities in the Bristol district. They show
a considerable amount of variability, but are at present, no doubt,
all to be included under Acrodus minimus.

Small, deeply-biconcave, vertebral centra, 4 to 5 millimetres in
diameter, occasionally occur, as they do at Aust and Emborough.
Apparently they have not yet received a name.

Dipnoi.
Ceratodus latissimus, Ag.—Ceratodus-teeth are not uncommon at
Sodbury, though less plentiful than at Aust. They are grouped in
the comprehensive species C. latissimus=C. polymorphus, Miall.

1 « Beitrage zur Palaont. Wiirtt.’ 1844, pl. ix, fig. 8.

Ann. & Mag. Nat. Hist. ser. 6, vol. iii (1889) pl. xiv.

Rep. Brit. Assoc. 1894 (Oxford) pp. 657-58.

‘Der Jura’ 1858, pl. ii, fig. 15.

Quart. Journ. Geol. Soe. vol. xxxvii (1881) p. 416 & pl. xxii, fig. 1.
° * Poiss. Foss.’ vol. ili (1833-48) p. 201.

Q.J.G.8. No. 238. P

uo &® | W

210 PROF. REYNOLDS AND MR, VAUGHAN ON THE [May 1904,

Teleostomi.

Sauruchthys acwminatus, Ag.—The teeth to which this name
is commonly applied occur in very large numbers, and are, with the
exception of those of Acrodus minimus, the most plentiful fossils
met with. Dr. Smith Woodward ! remarks on the close relationship
between the imperfectly-known genus Saurichthys and the better-
known genus Belonorhynchus, and tentatively suggests that the two
may really belong to the same genus. Mr. Montagu Browne,’ on
the other hand, suggests that Saurichthys is ‘a non-existent piscine
genus, and that the teeth referred to under this name can _ be
assigned to labyrinthodonts, Plescosaurus, Hybodus, Gyrolepis, and
perhaps Colobodus. The Sodbury material consists entirely of
isolated teeth, and affords no assistance in the settlement of this
question.

Sargodon tomecus, Plhen.—Small teeth with long roots and some-
what chisel-shaped crowns, described under the above name by
Plieninger,*® occur somewhat sparingly, as they do at Aust and
many other Rheetic localities in the Bristol district. With them
are found teeth which differ from them only in having knob-like
instead of chisel-shaped crowns, and have been described under the
name of Psammodus orbicularis by Meyer & Plieninger and under
that of Sphwrodus minimus by Agassiz. Pleninger suggested, and
the suggestion is supported by Dr. Smith Woodward,‘ that these
belong to the same animal as the typical chisel-shaped teeth.
Mr. Montagu Browne ® suggests that the knob-like teeth are to be
referred to Colobodus maximus (Quenstedt).

Gyrolepis Alberitt, Ag—The small striated scales of Gyrolepis
are very common. ‘They vary a good deal in size and in the state
of preservation, some being much rubbed. Agassiz recognized
several species, based on the form of the scales; but Dames °
showed that probably the form of the scale varied in different
parts of the animal’s body, and that the three forms of scale
described by Agassiz may all belong to one and the same fish.
This view is accepted by Dr. Smith Woodward.’

Notes on the Position of the Bone-Bed.

Although the extreme variability of the Rhetic Bone-Bed or
Beds in number, position, and development is well known, it may
perhaps be worth while to summarize its (or their) distribution in
the Bristol district. The typical position of the Bone-Bed
may be said to be at the base of the Black-Shale

1 Ann, & Mag. Nat. Hist. ser. 6, vol. 1i1 (1889) p. 302.

* Rep. Brit. Assoc. 1894 (Oxford) p. 657.

* Jahresh. Ver. vaterl. Naturk. Wurtt. vol. iii (1847) p. 165.

4 Catal. Foss. Fishes Brit. Mus. pt. iii (1895) p. 67.

Rep. Brit. Assoc. 1891 (Cardiff) p. 645.

Paleont. Abhandl. vol. iv (1888) p. 143.

Trans. Leicester Lit. & Phil. Soc. n. s. vol. i, pt. xi (1889) p. 20, and Catal.
Foss. Fishes Brit. Mus. pt. i (1891) p. 510.

I ao oe

Vol. 60.] © RHZTIC OF THE SOUTH-WALES DIRECT LINE. 211

Series. A Bone-Bed occupies this position in the Sodbury
section, at Patchway, Redland, Sedbury Cliff, Watchet, Penarth,
and Emborough. At Gold Cliff, near Newport, a Bone-Bed
underlies 3 feet of Tea-Green Marls. In several other well-known
sections it lies a short distance above the base. Thus at Aust it
lies 9 inches, at Wainlode Cliff 2 feet, and at Coombe Hill 33 feet,
above the base of the Black-Shale Series.

Although more or less isolated vertebrate remains may be met
with, no true Bone-Bed has been recorded at the Rheetic sections
of Wells, Shepton Mallet, Uphill, Pylle Hill, Saltford, Knowle,
and Stoke Gifford. At most of these sections, however, a band
of hard sandstone or tough limestone, with a smaller or greater
number of vertebrate remains, occurs at or near the base of the
Black-Shale Series, and is regarded as the equivalent of the Bone-
Bed. Thus, at Pylle Hill, a very thin and irregular seam of pyritic
grit, containing scales, teeth, and coprolites of fishes, occurs at the
base; and at Wells there is a tough bluish-brown limestone in
the same position. Similar bands occur at other horizons in the
northern part of the district. Thus, at Chaxhill, a micaceous sand-
stone, regarded by Mr. L. Richardson as the equivalent of the Bone-
Bed, overlies 7 feet of alternating shales and micaceous sandstones ;
and at Puriton, a somewhat similar bed of sandstone, passing into
impure limestone, is recorded in the vertical section of the Geo-
logical Survey, at a height of 203 feet above the base of the Black-
Shale Series.

In various sections more than one Bone-Bed is met with. Thus,
in the Penarth (Lavernock) section, while a typical but very irre-
guiarly-developed Bone-Bed occurs at the base of the Black Shales,
a second and thinner Bone-Bed is found at a height of + feet from
the base. At Aust, in addition to the well-known basal Bone-Bed,
there are indications of a second some 3 feet above the base of the
Black Shales. At Emborough the principal Bone-Bed is at the base
of the Black Shales, while a second and thinner one occurs at the
top; and a band of conglomerate with scales and teeth underlies
some 3 feet of sand and sandstone which intervene between the
Black Shales and the Tea-Green Marls.

In the coast-section to the east of Watchet, in addition to the prin-
cipal Bone-Bed at the base of the Black Shales, Prof. Boyd Dawkins
describes two thinner Bone-Beds, consisting of hard sandstone
with many fish-teeth, and occurring at a height of about 10 feet
from the base. AtSedbury Cliff, in addition to the Bone-Bed at the
base of the section, Mr. Richardson records a band with coprolites,
fish-teeth, and an ichthyodorulite, which lies at about the middle of
the Black Shales. At Garden Cliff the principal Bone-Bed occurs
at a height of about 63 feet from the base of the Black-Shale
Series. Lower down are the upper and lower bands of Pullastra-
sandstone, each of which contains numerous vertebrate remains. At
Wainlode Cliff, too, in addition to the main Bone-Bed 2 feet from
the base of the Black Shales, a second band 10 feet higher up was
noted by Brodie ; in Mr. Richardson’s recent account of the section,

P2

212 PROF. REYNOLDS AND MR. VAUGHAN ON THE [May 1904,

a limestone-band with vertebrate remains is recorded, but hardly
such a deposit as could strictly be termed a Bone-Bed.

A consideration of the geographical position of the above
localities, shows that throughout Somerset, with the exception
of Emborough and Watchet, no true Bone-Bed has been recorded.
In the district to the immediate north of Bristol—Redland, Aust,
Patchway, Sodbury, but not Stoke Gifford—there is a single, well-
marked Bone-Bed at, or very slightly above, the base of the Black-
Shale Series; while farther north, in the Gloucester district, the
principal Bone-Bed tends to lie at a greater distance from the base
of the Black Shales.

The facts summarized above seem to render it clear that the
principal Bone-Beds of the various sections in the Bristol district
cannot be regarded as the homotaxial equivalents of one another;
a conclusion to which, as already stated (p. 200), we have been
led by a comparison of the Sodbury section with that at Garden

Cliff.

The following is a list of the principal localities in the Bristol
district where a section showing the base of the Rhetic Series
occurs, with some references to the most recent, complete, or
accessible descriptions of the sections :—

Aust.—vVert. Sect., Geol. Surv. sheet 46, no. 6; W. J. Sollas, Proc. Geol.
Assoc. vol. vi (1880) pp. 385-86 ; Brit. Assoc. 1898 (Bristol), ‘Excursion
to Aust & Overcourt, p. 5; & A. Rendle Short, Quart. Journ. Geol. Soc.
vol. lx (1904) p. 178.

Chaxhill.—L. Richardson, Proc. Cottesw. Nat. Field-Club, vol. xiv, pt. ii
(1903) p. 175.

Coombe Hill.—Vert. Sect., Geol. Surv. sheet 47, no.7; & L. Richardson,
op. eit. p. 148.

Cotham Road.—A. Rendle Short, Quart. Journ. Geol. Soe. vol. lx (1904)
05 LTT:

Miiité ougho Lloyd Morgan & 8. I. Reynolds, Proc. Bristol Nat. Soe.
vol. ix, pt. ii (1901, issued for 1899) p. 109.

Garden Cliff, Westbury.—Vert. Sect., Geol. Surv. sheet 46, no. 7; & L.
Richardson, op. cit. p. 154.

Gold Cliff, near Newport.—J. E. Lee, Rep. Brit. Assoc. 1872 (Brighton)
Trans. Sect. p. 116; & H. B. Woodward, Proc. Geol. Assoc. vol. x
(1888) p. 538.

Knowle.—Vert. Sect., Geol. Surv. sheet 46, no. 4.

New Clifton.—See Redland.

Patchway.—Vert. Sect., Geol. Surv. sheet 46, no. 8.

Penarth and Lavernock.—Vert. Sect., Geol. Surv. sheet 47, nos. 1 & 3;
R. Etheridge, Trans. Cardiff Nat. Soc. vol. iii (1872) p. 39; & H. B.
Woodward, Proc. Geol. Assoc. vol. x (1888) p. 529.

Puriton.—Vert. Sect., Geol. Surv. sheet 46, no. 1.

Pylle Hill.—E. Wilson, Quart. Journ. Geol. Soe. vol. xlvii (1891) p. 545.

Radstock (Clan Down).—W. Buckland & W. D. Conybeare, Trans. Geol.
Soc. 2nd ser. vol. i, pt. ii (1824) p. 278.

Redland.—W. H. Wickes, Proc. Bristol Nat. Soc. vol. ix, pt. ii (1901, issued
for 1899) p. 99; J. Parsons, ibid. p. 104; & A. Rendle Short, Quart.
Journ. Geol. Soe. vol. lx (1904) p. 170.

Saltford.—Vert. Sect., Geol. Surv. sheet 46, no. 9.

QuarT. JOURN. GEOL. Soc. VoL. LX, PL. XVIII.

Fia. 3a.

Fia. 3.

Colla.

Bemrose,

J. W. Tutcher, Photogr.

RHATIC LAMELLIBRANCHIATA.

Vol. 60, | RHETIC OF THE SOUTH-WALES DIRECT LIN®. 213

Sedbury Cliffi—L. Richardson, Quart. Journ. Geol. Soc. vol. lix (1903)
p- 390 & pl. xxiv.

Shepton Mallet.—Vert. Sect. Geol. Surv. sheet 46, no. 15.

Uphill.—Vert. Sect., Geol. Surv. sheet 46, no. 3.

Wainlode Cliff—L. Richardson, Proc, Cottesw. Nat. Field-Club, vol. xiv,
pt. 11 (1903) p. 128.

Watchet.—W. Boyd Dawkins, Quart. Journ. Geol. Soc. vol. xx (1864)

p. 396.
Wells.—Vert. Sect., Geol. Surv. sheet 46, no. 14.

EXPLANATION OF PLATE XVIII.

Rhetic Lamellibranchiata.—All the figures are of the natural size.
Fig. 1. Anomia sp. (See p. 201.)
Figs. 2 & 2a. Pecten valoniensis, Defr. (See p. 202.)
3 &8a. Modiola sodburiensis, sp. nov. (See p. 203.)
Fig. 4. Cardinia concinna, Sow. aff. reqularis, Terq. (See p. 204.)
5. Fragment of Plicatula cloacina, sp. nov. (See p. 202.)

{We are greatly indebted to Mr. J. W. Tutcher for the excellent photographs
from which the figures in this plate are reproduced. |

Discussion.

Mr. Srrawan testified to the great value of the observations made
by the Authors on the sections that had been opened up on the new
line of railway. He had had an opportunity of visiting the
Chipping-Sodbury cutting, and had been particularly struck with
the form of the Paleozoic floor under the Rhetic shales. In one
place a small crag, formed by a hard quartz-grit interbedded in the
Carboniferous Limestone, projected above the generally-even level
of that floor and had yielded great blocks which lay at its foot
embedded in the shales. Another projecting mass, formed by the
upper beds of the Old Red Sandstone, had formed an island and
subsequently a shoal in the earliest Rhetic sediments. Its surface,
recently cleared of the shales, showed the rounding and smoothing
by the Rhetic waves in extraordinary freshness. In strong con-
trast to this was the base of the Keuper Marl on the other side of
Lilliput Bridge, where the old cliff showed no such wave-action,
but had been littered up with a talus of rough blocks.

The earliest Rhetic sediments thinned out on the flanks of the
Old-Red-Sandstone crag to which he had referred, but the later beds
overspread it, curving gently upward and thinning as they did so.
The Authors showed the Bone-Bed as extending continuously over
the surface of the old rock, which suggested that it might be not
strictly contemporaneous, but a littoral representative of any part
of the Lower Rhetic shales. It indicated merely a sudden change
of physical conditions.

The Rey. H. H. Winwoop referred to the great interest attaching
to these Rheetic beds, at least among West-of-England geologists,
and regretted the absence of the Authors, who had done such good

214 RH#/ETIC OF THE SOUTH-WALES DIRECT LINE. [May 1904,

work in these sections. He wished to ask a few questions by way
of explanation, not of criticism. What was their definition of the
‘true Bone-Bed’? If fish-scales and teeth were any guide, he had
found both in a thin band of limestone in the Black Shales, on the
south side of Stoke-Gifford cutting. Again, it was stated that no
true Bone-Bed had been recorded in Somerset, except at Emborough
and Watchet; but he had found a fish (Pholidophorus) at the base
of the Black Shales, at Newbridge-Hill cutting, near Bath. What
evidence, moreover, was there for their division of the strata into
Upper, Middle, and Lower Rhetic? In conclusion, he drew
attention to the surface of the Paleozoic floor, smoothed and planed
down by the sea which deposited these Rheetic beds.

Qn

Vol. 60. | THE DERBY EARTHQUAKES OF 1903. 21

16. The Dersy Earruavakss of Marcon 247TH and May 3rp, 1903.
By Cartes Davison, Sc.D., F.G.S. (Read February 24th,
1904.)

[Puate XIX—Map. |

As a seismic region, Derbyshire is marked by few earthquakes,
though parts, and even the whole, of the county are occasionally
disturbed by shocks from other British centres. To find one that
will compare in strength with the principal subject of this paper,
we must go back more than a century, to November 18th, 1795,
when a shock was felt over a district reaching in one direction from
Leeds to Bristol, and in the other from Norwich to Liverpool.
The dimensions of the disturbed area are given by Dr. E. W. Gray,
F.R.S.,. as about 165 miles from north to south, and about
175 miles from east to west. ‘In this latter direction, or rather
from north-east to south-west,’ he remarks, ‘it may be said to
have reached nearly across the island.’ The area disturbed cannot
have been less, and may have been much more, than 23,000 square
miles; while, if we may judge from the places where chimneys
were wholly or partly destroyed (Derby, Chesterfield, and Ashover),
the epicentre may have coincided approximately with that of the
principal earthquake of 1903.

In another respect there seems to have been a close resemblance
between the two shocks. It is probable from Dr. Gray’s account
(op. cit. p. 365), that the earthquake of 1795 was what I have termed
a *‘ twin ’-earthquake, that it consisted of two distinct parts separated
by a very short interval of rest and quiet. That this was a charac-
teristic feature of the earthquake of 1903 was evident from the
earliest reports; and, on this account, and also since the district is
a favourable one for such investigations, I endeavoured to make an
unusually-detailed study of the shock.” If, in so doing, I have met
with any measure of success, it 1s almost entirely owing to the
kindness of the very large number of correspondents who have sent
me reports, to the courtesy of many newspaper-editors who have
given a wide circulation to my inquiries, and not least to the
invaluable help which I have received from Sir John G. N. Alleyne,
Bart., Mr. H. H. Arnold-Bemrose, F.G.S., Mr. J. E. Bolton of
Kckington, Mr. J. Darby, Hon. Secretary of the Wolverhampton
Naturalists’ Field-Club, Mr. T. Gledhill of Dronfield, Mr. E. O.
Powell, headmaster of the Grammar-School, Stafford, the Rev. C.
Price of Denstone College, Mr. A. H. Stokes, F.G.S., H.M. Inspector
of Mines, Mr. P. K. Tollit, headmaster of the Grammar-School,
Derby, Dr. G. 8. Turpin, headmaster of the High School, Nottingham,
and Mr. F. W. Webb, manager of the London & North-Western

* Phil. Trans. Roy. Soe. vol. lxxxvi (1796) pp. 353-81.
2 The expenses of the investigation were defrayed from a grant received
from the Government Research Fund.

216 DR. CHARLES DAVISON ON THE [May 1904,

Railway locomotive-department at Crewe. My debt to Mr. Arnold-
Bemrose may to some extent be realized by the statement that I
have to thank him for more than 170 records, many of them the
results of personal interviews with observers, for a classified series of
newspaper-reports, for the enlargement of the seismographic record
which appears in fig. 1 (p. 220), and for information on the geological
structure of the epicentral district. Without this timely aid, the
gaps in our knowledge of the Derby earthquake would have been
more serious, as well as more numerous, than those which at
present exist.

The undoubted earthquakes were four in number, namely: |

a. March 24th, 1.30 p.m. (Principal earthquake.)
6. March 24th, about 1.45 p.m.

c. March 24th, about 5 p.m.

d. May 3rd, 9.22 p.m.

Besides these, eight other disturbances are reported, three before
and five after the principal earthquake, but the evidence is
insufficient to decide their seismic origin. They are as follows :—

March 28rd, about 1.45 p.m.: Abbotshulme (near Rocester). Two persons

felt a shock.

March 24th, about 5 a.m.: Kirk Langley. Two persons felt a shock similar

to the principal shock.

March 24th, about 10.55 a.mw.: Abbotshulme. One person felt a shock.

March 24th, about 1.50 p.m.: Tissington. A very slight shock.

March 25th, 0.30 a.m.: Fenny Bentley. <A vibration without noise.

March 25th, about 6 a.m.: Draycott. <A slight shock.

April 2nd, 2.30 a.m.: Duffield. A slight rumbling noise.

April 5rd, 1.17 a.m.: Duffield. A slight rumbling noise.

Tur PRINCIPAL EARTHQUAKE.

a. March 24th, 1.30 p.m.

Intensity, 7 (nearly 8); centre of isoseismal 7, lat. 538° 3-1’ N., long.
1° 41°5' W. Number of records 1136, from 528 places; and 63 negative
records from 56 places.

Time of Occurrence.

The total number of records of the time is 565. Of these, 71
are considered by their observers to be accurate to the nearest
minute. Though two of them are as low as 1.25 and one as high
as 1.36 p.m., the majority lie between closer limits, 36 records
giving the time as 1.30, 10 as 1.31, and 8 as 1.382. The mean of
40 records from places within the isoseismal 6 is 1” 30™ 15%,
Three estimates are probably of greater value than the rest, namely,
1" 30™ 6° for Derby (12 miles from the centre), 1° 31™ for Alsager
(26 miles), and 1" 31™ 5’ for Handforth, near Stockport (30 miles).

In these three records no reference is made to the particular
epoch timed—an element of some importance, considering the long
duration of the movement. As will be seen in a later section, the
first tremors reached Birmingham (41 miles from the centre) at
1” 30™ 19%, and Bidston (65 miles) at 1" 30™ 44°. Taking the

Vol. 60. ] DERBY EARTHQUAKES OF 1903, 217

_ velocity afterwards calculated (p. 223) into account, it is clear that
the time of the first vibrations at the epicentre must be within a
very few seconds of 1" 30™ 0° p.m., an estimate that agrees closely
with the mean recorded time within the isoseismal 6.

Isoseismal Lines and Disturbed Area.

On the map of the earthquake (Pl. XIX) are shown five isoseismal
lines. The innermost, corresponding to an intensity of less than 8
according to the Rossi-Forel scale, includes all the places but one
in which slight damage is known to have occurred to buildings.
In none was the injury more serious than the cracking of a poorly-
built wall, or the overthrow of a few chimney-pots accompanied
by the fall of some of the surrounding bricks. The bounding.
curve is elliptical in form, 163 miles long, 83 miles wide, and 112
square miles in area, the longer axis being directed N. 323° E. and
S. 323° W. The centre of the curve coincides with the village of
Kniveton, which les about 3 miles north-east of Ashbourne, in
lat. 53° 3°1' N., and long. 1° 41:5’ W.”

The next isoseismal, of intensity 7, is 233 miles long, 173 miles
wide, and 272 square miles in area, with its longer axis running
N. 33° E. and 8. 33° W. Its distance from the innermost isoseismal
is a little more than 33 miles on both sides of the axis. The
isoseismal 6 is 48 milesin length, 36 miles in width, and 1348 square
miles in area. Its longer axis is parallel to that of the isoseismal 7,
the distance between the curves being 12 miles on the north-west
side and 8 miles on the south-east. The isoseismal 5 is 76 miles
long, 69 miles wide, and contains 4060 square miles, its distance
from the isoseismal 6 being 17 miles towards the north-west and
16 miles towards the south-east.

Still more nearly circular is the outermost isoseismal, that of
intensity 4, which, as drawn, is 129 miles long from north-west
to south-east, 126 miles from north-east to south-west, and
12,000 square miles in area: its distance from the isoseismal 5
being 35 miles on the north-west side, and 25 miles on the south-
east. Owing, however, to the difficulty always experienced in
obtaining observations from outlying regions, it is possible that the
path of this curve is inaccurately laid down, and that the diver-
gence of the curve towards the north-west is largely,if not entirely,
due to a defective series of records from other quarters.

Records have also been received from a few places beyond this
isoseismal line—from Settle, Aysgarth, Richmond, and Easby
(1 mile east of Richmond), which are respectively 74, 21, 27, and
27 miles north of the isoseismal, and from Boston, 12 miles farther
to the east. If the disturbed area were bounded by a egircle
concentric with the isoseismal 4, it would contain 16,000 square
miles if the circle passed through Settle, 18,000 if through Boston,

? In a cottage at Alfreton (which is nearly 7 miles from the bounding curve)
a chimney-pot was thrown down, and some bricks in the chimney were
displaced.

218 DR. CHARLES DAVISON ON THE [May 1904,

22,000 if through Aysgarth, and 25,000 if it traversed Easby and
Richmond. Nothing, either in the time of occurrence or the
description given, throws the least doubt on the observations made
at these places. But, considering that at such distances they could
only have been furnished by exceptionally-keen observers, | think
that the disturbed area should be regarded as bounded by the
isoseismal +, and therefore as containing about 12,000 square
miles.

Nature of the Shock.

The following accounts are given to illustrate the twin-character
of the earthquake and its variation throughout the disturbed area.
Of the places referred to, Ashbourne and Darley Dale are close to
the longer axis of the inner isoseismals, the former being very near
the epicentre ; Duffield les on the continuation of the shorter axis
of the same curves, while Quarndon and Derby are respectively
14 and 3 miles from it.

At Ashbourne, two distinct shocks were felt, the first twice as long
as the second and also rather stronger: the impression produced by
both shock and sound being that a heavy article of furniture was
rapidly rolled in the room upstairs from east to west, and then,
after a pause of a second or two, was rolled a short way back again.
At Darley Dale there were also two parts, each of which began
with a low distant rumbling like the rushing of a strong wind, and
culminated in a violent shock as it passed underneath the house.
The second and stronger part was accompanied by an undulation
crossing the floor from the north-west; and, immediately after its
last: vibrations had died away, another slight shock was felt.

From Derby the accounts are very numerous, but in most
respects they agree closely. There were again two distinct shocks,
each lasting 3 seconds with an interval of half a second between
them, and consisting of vibrations having a period of about half a
second. At Quarndon, a rumbling sound was first heard; then
came a violent shock, as if a steam-roller had crashed into the
foundations of the house on the north-west side; the rumbling
continued for about 2 seconds, and, before it ceased, a second shock
was felt, but not so violent as the first, the rumbling gradually
dying away on the south-east. At Duffield only a single shock was
observed, a quivering motion during the loudest part of the rambling
sound, which resembled that made by a muffled peal of thunder or
by a sudden gust of wind.

With some exceptions, such as that last mentioned, the double
shock was observed in every part of the disturbed area. Towards
the north, it was clearly perceptible at Preston, Lytham, Aysgarth,
Settle, Richmond, and Doncaster ; towards the east, at Grantham,
Eagle, and Boston ; towards the south, at Barnt Green, Mere Hall,
and Hagley ; towards the west, at Shrewsbury and Vicar’s Cross
(near Chester). There is no evidence of the usual tendency of one
part to become evanescent at a considerable distance from the
epicentre.

Vol. 60. | DERBY EARTHQUAKES OF 1905. 219

_ Throughout the whole disturbed area, the double shock is dis-
tinctly recorded by 68 per cent. of the observers. In some parts
this percentage rises to more than 80, especially in an elongated
district about 50 miles in length, lying along the continuation
towards the south-west of the major axis of the innermost isoseismal.
In no large area does it fall below 48.

If, however, we plot the places where the double shock was felt,
and also those where only asingle series of vibrations was observed,
a definite law of variation is rendered evident. ‘The single shock
was felt chiefly within a narrow rectilinear band, about 5 miles
wide, running centrally across the inner isoseismals in a direction
from W. 34° N. to E, 34° S., that is, at right angles to the longer
axes of the isoseismals.* In the map (Pl. XIX) the boundaries of this
band are represented by broken lines. Outside the band, the interval
between the two parts of the shock was one of rest and quiet, its
average length over the whole disturbed area being exactly 3 seconds.
Close to the band (as at Derby) the interval was much shorter,
though still distinct; while, within the band, the shock generally
appeared continuous, the ends of the two parts overlapping,
although near the epicentral area, and close to the boundaries of the
band elsewhere (as at Quarndon), two maxima of intensity were
frequently perceived.

From the mere fact that the double shock was noticed at places
near the boundary of the disturbed area, it is evident that the two
parts were of nearly equal strength. If there had been any marked
difference, it would have been possible, with so large a number of
observations, to draw isoseismal lines for each part of the shock,
and thus to determine the positions of the two epicentres. As it
is, there is often considerable doubt as to which part was the
stronger. At Derby, for instance, the first part of the shock was
regarded as the stronger by 19 observers, and the second by 16;
while 5 considered the two parts as of approximately-equal in-
tensity. In the whele disturbed area, 61 per cent. of the observers
state that the first part was the stronger, and 39 per cent. the
second. Dividing the area into two portions by the axis of the
rectilinear band, 60 per cent. of the observers on the north-east
side, and 63 per cent. of those on the south-west side, regarded the
first part as the more intense.”

Origin of the Double Shock.

It is evident, from these accounts, that the double shock owed
its origin to two distinct impulses of nearly-equal strength ;

? It should perhaps be mentioned that the boundaries of this band were
laid down without any reference to the previously-drawn isoseismal lines, and
before the approximate positions of the two epicentres were known.

2 This is the average of 125 observations, estimates of 10 or more seconds
being oinitted.

3 This result, as will be seen from the followmg paragraphs, is due: (1) to
the approximate equality of the two impulses; and (2) to their occurrence at the
same instant. Jn each half of the disturbed area, the vibrations which formed
the first part of the shock were those which came from the nearer focus.

‘ard'sog "THE UT
=

‘uynpuad pojuozr.oy 0g un fg wnybuung yw patasihar ‘eogl ‘ywre youn fo aynnbyjzina ay) fo p.t099a4 ay, — | “Sty

Vol. 60. ] THE DERBY EARTHQUAKES OF 1903. 221

‘and the next point to be determined is whether they occurred
within the same focus at different times, within two foci at the
same time, or within two foci at different times. The theory of
two successive impulses within the same focus is negatived by the
existence of the rectilinear band within which the two parts of the
shock were superposed, and by the fact that the first part of the
shock was not everywhere the stronger. For the same reasons,
the double shock cannot be referred to the duplication of a single
initial impulse by reflection or refraction at the bounding surfaces
of different rocks, or by the separation of its direct and transverse
waves. There must, therefore, have been two distinct foci arranged
along a line parallel, or nearly so, to the longer axes of the isoseismal
curves ; and that the foci were practically detached is evident from
the cessation of all sound and movement during the interval
between the two parts of the shock.

One of the most interesting features of twin-earthquakes is the
occurrence of the second impulse before the vibrations from the
focus first in action have time to reach the other. In other words,
the second impulse is not a consequence of the first. In the
Hereford earthquake of 1896, the two impulses were separated by
a brief interval of time, and the two corresponding parts of the
shock coalesced within a hyperbolic band, the convexity of which
faced the focus first in action. In the Derby earthquake, however,
this band is rectilinear, showing that the two impulses must have
occurred at the same instant. They were therefore due to a single
generative effort, and it is on this account that I have given the
name of ‘ twins’ to this class of earthquakes.

Position of the Two Foci.

In the absence of isoseismal lines for each part of the shock, the
exact positions of the two epicentres cannot be determined. From
the form of the curves in Pl. XLA, however, it is probable that one
epicentre was situated near Ashbourne, and the other about 3 miles
west of Wirksworth: their centres being, therefore, about 8 or 9
miles apart.

Seismographic Records.

Records of the Derby earthquake were given by an Omori
horizontal pendulum at Birmingham, by a Milne seismograph at
Bidston (near Birkenhead), and by an astatic pendulum designed by
Dr. E. Wiechert at Gottingen. The first of these, which is the most
interesting ever obtained of a British earthquake, is reproduced in
fig. 1 (p. 220) from a photographic enlargement of the original record,
for which I am indebted to the kindness of Mr. Arnold-Bemrose.

The Omori pendulum belongs to the type first devised by
Mr. Gerard, of Aberdeen, in 1853, and afterwards re-discovered and
employed by Prof. Milne in his well-known seismograph. It differs
from the latter instrument in its mechanical form of registration, the
record being made by a fine point on a rotating surface of smoked

222 DR. CHARLES DAVISON ON THE [May 1904,

paper travelling at the rate of 10-8 millimetres per minute. Owing
to the short period of the vibrations at Birmingham, the heavy bob of
the pendulum acted almost as a steady point, the slight swinging of
the pendulum being evident in the large curve on which the seismic
waves are superposed. The movements of the ground in such a case
are magnified 13°7 times by the pendulum; and, as the original
record is also magnified 28°1 times by the enlargement in fig. 1, it
follows that the latter represents the actual movements multiplied
by 385.

An examination of the record under the microscope shows not the
slightest trace of movement before the first abrupt disturbance to
the east, which took place at 15 30" 19° p.w.,G.M.T. The diagram
is chiefly remarkable for the two prominent displacements to the
west, which occurred at 1° 30™ 23 and 1" 30™ 28%, and which no
doubt correspond to the two parts of the shock so widely observed.
It is difficult to determine accurately the periods of these two large
waves, owing to the width of the trace made by the recording pointer,
but in each case it seems to have been about 0-8 sec. At 1° 307315,
another oscillation of some importance took place, followed by a
series of 13 ripples with an average period of 0:84 sec. These are
all that are shown in fig. 1, but the original record continues with
a series of 79 still smaller ripples, with a slightly longer average
period of 1°03 secs., the last visible under the microscope occurring
at 1" 32™ 3°. The total duration of the disturbance as registered
in Birmingham was 1” 44°.

Making allowance for the width of the trace and the swinging of
the pendulum, the range of motion of the ground from east to west
was ‘078 millimetre during the first prominent displacement, and
‘O75 mm. during the second. Birmingham, however, lies 8. 11° W.
from the epicentre, and therefore, if we may assume that the
resultant movement was directed from that point, the total displace-
ments registered by the pendulum must have been ‘41 and °39
millimetre respectively. These, with periods of ‘8 sec., would corre-
spond to maximum accelerations of 12°6 and 12-0 millimetres per
sec. per sec., showing how nearly equal in strength were the two
principal parts of the shock. The values given seem to be too small
to produce a shock sensible in the centre of a busy city; and it is
therefore probable that the recorded range of motion is less than the
actual movement of the ground, owing to the unavoidable friction
between the pointer and the smoked paper and between the different
parts of the apparatus.

Bidston lies 65 miles west-north-west of the epicentre, and 83 miles
south-west of the rectilinear band. The method of registration in
the Milne seismograph being photographic, the paper is made to
travel much more slowly than in the Omori pendulum, and con-
sequently the diagrams are less detailed and the times of different
epochs are ascertainable with less accuracy. I am informed by
Mr. W. E. Plummer that

‘The record of the Derby earthquake is small, both in amplitude and duration.

Vol. 60. | DERBY EARTHQUAKES OF 1903. 273

The time of the first disturbance is 13.30.44 [that is, 1® 80™ 44 p.y.], as nearly
as it can be read off the diagram. The record gives evidence of but one impulse
which has moved the pendulum towards the west: the subsequent oscillations
of the pendulum, which are carried on for about 55 seconds, being due to the
original] disturbance. The greatest amplitude of oscillation is about 0-7 milli-
metre, and, as the movement dies away, there is no trace of the ordinary period
of the pendulum, which is about 16 seconds. The vibrations appear to have
accomplished themselves in a shorter time, so that the successive vibrations have
run into each other.’

One of the most interesting features of this record is the fact that
only one impulse was detected. Bidston being so close to the
rectilinear band, the interval between the two prominent vibrations

was too short to allow of their separate registration.

At the time of the earthquake, as Dr. Wiechert kindly informs me,
rather strong pulsations were being registered by his pendulums at
Gottingen ; and, on this account, ali measurements are to some
extent uncertain. The determinations of the epochs, for instance,
may err by as much as 5 seconds on either side of the times given.
The preliminary tremors, though very small, were distinctly recog-
nized with the aid of a lens, beginning at 12 33™ 32° ep... (G.M.T.);
their period was about 1 second, and their amplitude about -0001
millimetre. They were succeeded by a series of larger waves,
beginning at 1" 34™ 20%, and attaining their maximum at 1° 34™ 405,
with a period of between 2 and 3 seconds and an amplitude of about
-0007 millimetre. The total duration of the movement was about
12 minutes.

Velocity of the Earth-Waves.

The most accurate determinations of the time are probably those
given by the pendulums at Birmingham and Gottingen, the distances
of which places from the epicentre are 66 and SOS kilometres
respectively, or 41 and 502 miles. The interval between the
arrival of the first vibrations at these places being 193 seconds, and
of the maximum of the principal waves 257 seconds, it follows
that the preliminary tremors travelled with a velocity of 3-8 kilo-
metres (or 24 miles) per second, and the larger waves at the rate
of 2-9 kilometres (or 1°8 miles) per second. The former of these
values many be inaccurate, for we cannot be certain that the first
tremors recorded in Birmingham corresponded with those registered
in Gottingen; the latter value agrees closely with the estimates
made for many other earthquakes.

SounD-PHENOMENA.,
Isacoustie Lines and Sound-Area.

As persons differ considerably in their powers of hearing very
deep sounds, the short-period vibrations, in spreading outwards
from the origin, tend to become inaudible to a continually in-
creasing number of observers; and the rate of decline in audibility
may be represented by a series of isacoustic lines, or curves drawn

224 DR. CHARLES DAVISON ON THE [May 1904,

through places in which the percentage of observers who heard the
sound is the same. If, from any cause, such as the superposition
of sound-waves from two foci, the amplitude of the vibrations be
locally increased without a corresponding increase in their period,
the percentage of audibility will rise, and there will be an expansion
outwards of the isacoustic lines in the neighbourhood of the region
in question.

In the Derby earthquake, the smallness of the sound-area and
the scarcity of observations from places near its boundary, render
impossible the construction of a complete series of isacoustic lines.
On the map of the earthquake (Pl. XIX), only two such curves
(indicated by dotted lines) are shown, namely, those corresponding
to percentages of 95 and 90. In order to draw them, the whole
disturbed area was divided into squares by north-to-south and east-
to-west lines 10 miles apart; the percentage of observers within
each square who heard the sound was supposed to correspond to the
centre of the square, and the curves were then drawn through points
dividing the lines that join adjacent centres in the proper ratios. The
meaning of the curve marked 95, then, is that, if with any point on
it as a centre, a small circle be described, 95 per cent. of all the
observers within the included district heard the earthquake-sound.

The inner line (that marked 95) is 33 miles in length and 16
miles in greatest width, and the outer line (marked 90) 49 miles in
length and 19 miles in width. The greatest of these dimensions
being not more than five times a side of one of the squares, it
follows that details in the form of the curves are smoothed away by
the process of construction, and that the only important feature
that possesses a physical meaning is the general trend of the
curves in the direction of the rectilinear band within which the
single shock was observed. At places inside this band, the vibra-
tions from the two foci coalesced ; and so the earthquake-sound was
reinforced, and was consequently heard by a greater proportion of
observers. ‘Thus, the evidence of the sound-phenomena supports the
conclusion to which we were led by the nature of the shock, namely,
that the earthquake was caused by simultaneous fault-slips within
two detached foci.’

Excluding a few records from very distant places, the sound was
observed within the area bounded by the outer dotted line in Pl. XIX
—an area 101 miles long in the direction of the major axis of the
isoseismals, 98 miles wide, and containing about 7800 square miles,
or nearly two-thirds of the whole disturbed area. ‘The exceptional
records come from Ashton-in-Ribble, Lytham, and Southport in
Lancashire, and from Aysgarth and Settle in Yorkshire.

Within the isoseismal 7, no fewer than 97 per cent. of the

1 The insensible distortion of the isoseismal lines and the marked expansion
of the isacoustic lines in the direction of the rectilinear band, is due to the
brevity of the two principal vibrations of the shock and the long duration of the
two parts of the sound. Within the rectilinear band, there must have been a
still narrower band witbin which the two principal vibrations absolutely
coalesced ; but the area of the latter band was so small that the observations
from places within it seem to be entirely wanting.

Vol. 60. | DERBY FARTHQUAKES OF 1903. 225

observers heard the earthquake-sound ; in the surrounding zone (that
between the isoseismals 7 and 6) the percentage of audibility was
89; in the next (bounded by the isoseismals 6 and 5) 80; while,
between the isoseismal 5 and the boundary of the sound-area, it
fell to 65. In other words, within a radius of about 40 miles from
the epicentre, nine out of every ten persons heard the sound; but,
outside a surrounding zone 10 miles in width, the sound became
inaudible to all but the most acute observers.

Nature of the Sound.

The sound was generally a heavy rumble, deeper than any
thunder, a quick succession of reports, though sometimes appa-
rently continuous. ‘The low grating character of the sound is
illustrated in many descriptions, such as its comparison with a
number of steam-rollers passing over a very uneven road, a very
large barrel rolling over cobble-stones, a peal of thunder in a hilly
country, a great fall of rock in underground workings, a confusion
of knockings or the trampling of many feet; the rapid rush of the
sound is shown by frequent reference to runaway traction-engines,
a number of big vans galloping up a road, or the moving of heavy
furniture in a great hurry; the approach to continuity by compa-
risons with a steam threshing-machine at a distance, or the rush of
a strong wind.

The total number of descriptions in the whole sound-area amounts
to 745. In 53 per cent. of these, the sound is compared to passing
traction-engines, etc., in 21 per cent. to thunder, in 5 to wind, in 8
to the tipping of a load of stones, in 4 to the fall of a heavy body, in
7 to explosions, and in 3 per cent. to miscellaneous sounds.

In any one place, many different types of comparison are employed,
certain vibrations of the series being audible to some persons and
not to others. Thus, at Derby, 61 per cent. of the observers com-
pared the sound to passing traction-engines, ete., 11 per cent. to
thunder, 6 to wind, 11 to loads of stone falling, 5 to the fall of a
heavy body, 3 to explosions, and 2 per cent. to miscellaneous
sounds. These proportions also vary in different parts of the sound-
area, though (except as regards distance) the law of variation
cannot be determined with certainty. The percentage of comparisons
to passing traction-engines, etc., is 46 within the isoseismal 7, 53
between the isoseismals 7 and 6, 56 between the isoseismals 6 and
5, and 59 between the isoseismal 5 and the boundary of the sound-
area; for thunder, the corresponding percentages are 32, 21, 16,
and 14. Thus, with increasing distance from the origin, the sound
tends to become smoother and more monotonous, owing to the gradual
extinction of the limiting sound-vibrations, and especially those of
longest period.

Relation of the Sound to the Double Series
of Vibrations.

In many of the detailed accounts, reference is made to two
Q.J.G.8. No. 238. a

226 DR. CHARLES DAVISON ON THE [May 1904,

distinct sounds, accompanying each part of the shock, and sepa-
rated by a brief interval of rest and quiet. Few observers,
however, noted the relative intensity of both parts of the sound and
shock. The first part of both sound and shock was the more intense
according to 7 observers, the second part according to 9, while
1 considered them to be approximately equal in intensity. Again,
8 observers state that the first part of the shock was the stronger
and that no sound was heard with the second part; and 1 that the
second part of the shock was the stronger, while no sound accom-
panied the first. Thus, all observers agree in connecting the louder
part of the sound with the stronger part of the shock.

Time-Relations of the Sound and Shock.

In the following table, the letters p, ¢, and f indicate the number
of records per cent.in which the beginning or end of the sound
preceded, coincided with, or followed, the corresponding epoch of
the shock; the letters g, e, and / indicate the number of records
per cent. in which the duration of the sound was greater than, equal
to, or less than, that of the shock.’ The last line of the table
contains the average percentages for four strong earthquakes,
namely, the Pembroke earthquakes of 1892 and 1893, the Hereford
earthquake of 1896, and the Inverness earthquake of 1901.

| BEGINNING. Enp. a
Duration.
| —-— A | 4+ aaa |
HA he a | ee plies Dh CN aes € | ‘h
Within isoseismal 7 ........-..0++- 63 | 34| 3 | 20 | 53 | 27 | 59| 37] 5
Between isoseismals 7 andG....| 43 | 40 | 7 | 17 | 52 | 31 | 48 AB Ane
<5 5 Gand’5 .2./ 551 37) 8 | 233) Ge4 aS) | Soa aie
bs Bs 5 and the | | =,q | o¢ wy
boundary of the sound-area | 00 en ey oe ee ete
|
Whole sound-area...............+.- 57 | od (al, | 214 55 |} 24 46 | AG eg
3 | 21 6

Average for strong earthquakes. 76 | 15 | 8 | 19 | 26 | 56 | 7

eat

A comparison of the last two lines of the table shows that, in the
Derby earthquake, there was a closer approach than usual to coin-
cidence in both terminal epochs and therefore to equality in duration.
Moreover, this tendency was almost as marked in the central region
as in the outer zones, from which we may infer: (1) that the sound-
waves travelled with the same, or very nearly the same, velocity as
those of larger amplitude and longer period, and (2) that the mar-
ginal regions of the foci were of comparatively-small dimensions in
a horizontal direction.

1 The number of records from the outer zone (that between the isoseismal 5
and the boundary of the sound-area) is much less than from the others, and
the corresponding percentages are therefore of inferior value.

Vol. 60.] DERBY EARTHQUAKES OF 1903. 227

OBSERVATIONS IN MINEs.

As observations in mines have hitherto been few in number, I
endeavoured to obtain accounts from many of those surrounding the
epicentral region. For some of the most valuable records, I am in-
debted to Mr. H. H. Arnold-Bemrose, F.G.S., and Mr. A. H. Stokes,
F.G.S., H.M. Inspector of Mines. The total number received is
48 from 32 mines, most of which are situated between two lines
running east and north-east from the centre of the isoseismal 7.

From the south-western quarter observations are entirely wanting,
the earthquake having passed unnoticed in the pits of Cannock Chase.
Towards the west, it was perceived as far as Bucknall near Stoke-
on-Trent (19 miles from the centre); towards the north-west, at
Monsal Wale near Buxton (18 miles, 117 yards deep) ; towards the
north-east, at Eckington (22 miles); towards the east, at Hucknall
Torkard (20 miles, 500 yards deep) and Bulwell (20 miles, 300 yards
deep) ; and towards the south at Swadlincote, near Burton-on-l'rent
20 miles, 470 yards deep).

The general impression produced by the earthquake was that an
explosion or fall of rock had taken place in some distant part of the
mine. In the pits at Clay Cross and Morton (situated between
Alfreton and Chesterfield), both parts of the shock were felt, the
first part being the stronger and, at Clay Cross, accompanied by
the louder noise. In Pees pits, at Glapwell, Pilsley, and Swancote
(all in the Alfreton district), the shock was strong enough to detach
small pieces of shale from the roof. At Tibshelf (4 miles from
Alfreton), the shock caused the air in the mine to vibrate, as if from
an explosion.

The sound seems to have differed slightly from that observed on
the surface, in being less intermittent and more monotonous, closely
resembling that made by a railway-train passing over iron girders
or a wooden bridge, and in a few cases not unlike that of an
explosion of firedamp or a heavy fall of rock.

The distribution of intensity of the shock and sound presents
several features of interest, which seem w orthy of record :—

(1) The shock, as a rule, was not felt in the more distant mines.
The sound only was observed in the pits at Eckington, Teversall
(18 miles from the centre), Sutton-in-Ashfield (18 miles), Hucknall
Torkard, Ilkeston (16 miles, about 4U0 yards deep), Swadlincote,
and Bucknall; but in two others, Monsal Wale and Bulwell, the
movement was also perceived. It would seem, then, that at a dis-
tance the sound was a much more prominent feature than the shock ;
and this relative prominence was probably uot accidental, for men
lying down to work would be in a favourable position for feeling a
slight tremor. Similar observations were made during the Here-
ford earthquake of 1896, the shock being noticed at a distance of at
least 20 miles, and the sound as far as Chasetown near Walsall,
54 miles from the centre.

(2) In the Great Rake lead-mine at Brassington, at a depth of
160 yards, and only 2? miles from the centre, no shock was felt by

228 DR. CHARLES DAVISON ON THE [May 1904,

any of the men, although a ‘ dreadful roaring noise’ was heard. As
the mine must be in the immediate neighbourhood of the north-
eastern focus, and especially of its marginal regions, it is probable
that the sound overpowered all other sensations.

(3) In several cases, the sound appeared to be more overhead
than below. At Clay Cross, according to one observer, the sound
was noticed ‘more as in the roof than on the floor’; according to
another, there was ‘a rumbling noise above, as though a train was
passing over.’ In the Manners Colliery, near Ilkeston, at a depth
of about 400 yards, the sound is described as like that of a train
passing close overhead, while some of the men thought that it was
caused by a break in the overlying strata. At Pilsley, near Clay
Cross, the rumbling resembled that of a train of trucks passing over
the workings. Lastly, at Swadlincote, near Burton-on-Trent, men
working in the Eureka seam at a depth of 400 yards were alarmed
by a rumbling noise ‘ passing overhead, like a railway-train passing
over a wooden bridge’; others in the Kilburn seam, 470 yards below
the surface, heard a heavy rumbling noise, ‘as though the stone-
head was falling in,’ which seemed to pass over their heads and die
away in the distance.’

(4) Mr. G. 8. Bragge, who kindly communicated the last account,
informs me that the rumbling noise was also heard in some cases
in the Woodfield seam, 350 yards from the surface, but no notice
was taken of it. In the workings of the Little Coal, at a depth of
about 220 yards, he was unable to find that any unusual noise was
heard at all, It would seem, then, that the intensity of the sound
increased with the depth of the workings.

Errsect oN UNDERGROUND WATER.

The only observation under this heading that I possess is one
communicated to me by Mr. Arnold-Bemrose, from Mr. T. Webster
at Hognaston, a village which hes about a mile east of the centre,
and probably not far from the line of the earthquake-fault. Shortly
after the earthquake, the water of the village-well was found to be
of a milky colour. Mr. Webster then emptied the well three times,
and saw the water bubbling out of the springs at the bottom quite
thick, as if with powdered lime. It remained so for two or three
days before it returned to its normal clearness, after which a white
sediment remained at the bottom fora few weeks. Mr. Webster adds
that he has known the well for 35 years, and that neither he nor
the oldest inhabitant can remember a similar occurrence. Whether
the sediment was a result of the fault-slip that caused the earthquake,
or merely a secondary effect of the shock itself, is doubtful, though

1 A similar observation was made in amine at Ashover, near Matlock, during
the earthquake of November 18th, 1795. The men at work heard ‘a rushing
rumbling kind of noise, which appeared to be at a distance, and to come nearer
and nearer, until it seemed to pass over them, and die away.’ The position of
the epicentre is unknown, but it was probably not very distant, for several
chimneys were thrown down at Ashoyer, Phil. Trans. Roy. Soc. vol. lxxxvi
(1796) p. 359.

Vol. 60.] DERBY EARTHQUAKES OF 1903. 229

the former is not an improbable origin. In any case, owing to the
proximity of Hognaston to the earthquake-fauit, the observation is
one of considerable interest.

AFTER-SHOCKs.

6b. March 24th, about 1.45 p.m.

The only records of this after-shock come from Abbotshulme
(near Rocester), Bakewell, and Tissington. There was a slight
tremor at all three places, and at Abbotshulme a rumbling sound
was heard.

c. March 24th, about 5 P.M.

A slight shock was felt at Brailsford, Fenny Bentley, and One-
cote (near Leek). There is no record of any accompanying sound.

d. May 3rd, 9.22 p.m.

Intensity, 5; centre of isoseismal 4, lat. 23° 2-4’ N., long. 1° 39-9’ W.
Number of records, 62, from 42 places in Derbyshire, and 11 from 10 places
in Staffordshire; and 35 negative records from 30 places.

Time of Occurrence.

As the earthquake was not recorded by any seismograph, we
have to rely on local observations of the time of occurrence. ‘The
time given above was that determined by two signalmen in different
boxes on the railway-line between Derby and Duffield. It agrees
closely, moreover, with the mean of all the more careful obser-
vations, namely, 9.214 p.m.

Isoseismal Lines and Disturbed Area.

On the map of this after-shock (fig. 2, p. 230) are shown six curves,
the isoseismals 5 and 4 being indicated by continuous lines, the
boundary of the disturbed area by the outer line continuous in part
but mostly broken, the boundary of the sound-area by the dotted line,
while the two inner isoseismal lines of the principal earthquake are
indicated by broken-and-dotted lines. The isoseismal 5 is 102 miles
long, 57 miles wide, and about 44 square miles in area. The
isoseismal 4 (the most accurately drawn of the series) is 19 miles
long and 12 miles wide, and contains about 179 square miles. Its
centre is about one mile south-west of Hognaston, and the direction
of its longer axis is N. 25° E. and 8. 25° W. ‘The course of the
boundary of the disturbed area is doubtful, except in the neigh-
bourhood of Derby, Ripley, and Cheadle. As drawn, it is 31 miles
long, 24 miles wide, and about 585 square miles in area. The >
distances between the isoseismals 5, 4, and that which forms the
boundary of the disturbed area, are respectively 3:7 and 6-4 miles
on the north-west side, and 3-0 and 5:0 miles on the south-east
side. Taking account of possible error in the tracing of these
curves, it follows that the originating fault must, in the neigh-
bourhood of the focus, run about N. 25° E. and §, 25° W., hade

230 DR. CHARLES DAVISON ON THE [May 1904,

towards the north-west, and intersect the surface along a line
passing near, or a short distance to the south-east of Hognaston.
The epicentre, or the chief part of it, evidently lies between the
two epicentres of the principal earthquake (of March 24th); while
the displacement towards the east or south-east of the isoseismal lines
with respect to those of the principal shock shows that, if connected
with the same fault, the focus must have been situated much nearer
to the surface. The latter inference is also supported by the
closeness of the isoseismals, which is indicative of a rapid decline in
intensity from the epicentre outwards.

Fig. 2.—Map of ihe Derby earthquake of May 3rd, 1903.

we] -—--..
ee -~

—o—
Ai :

iheton
Hognaston

fo)
Kniveton

hbourne ;
/

4 Duffield

SAbbotshulme ”
SS A

oe

—_—.—""

a5
VOCE eee Reh OC

Pals
Boundat

Seale of Miles
2 6

-
=
—w-..----

Nature of the Shock.

Tn most places, the shock is described as a sudden shiver or short
tremor, its average duration being about 34 seconds. Of the 36
observers who refer to the nature of the shock, 29 distinctly state
that it consisted of only one part, and the remainder do not enter
into details. The shock was, therefore, not a twin, but due to a
disturbance within a single continuous focus.

Vol. 60.] DERBY FARTHQUAKES OF 1903. 231

Sound-Phenomena.

The boundary of the sound-area is shown by the dotted curve in
fig. 2. Towards the south, its course is somewhat uncertain, but
it probably does not deviate by more than a fraction of a mile from
the position there laid down. The boundary, as drawn, is 24 miles
long, 17 miles wide, and contains about 320 square miles. The
sound was heard by 92 per cent. of all the observers. It was
compared to passing traction-engines, ete., in 45 per cent. of the
records, to thunder in 389 per cent., wind in 6, loads of stones falling
in 3, explosions in 3, and to miscellaneous sounds in 3 per cent.
The beginning of the sound is said to have preceded that of the
shock in 47 per cent. of the records, and to have coincided with it
in 53 per cent. ; while the end of the sound is said to have coincided
with that of the shock in 58 per cent. of the records, and followed
it in 42 per cent. Twelve observers noted the time-relations of
both terminal epochs; according to six of them, the duration of
the sound was greater than, and according to the other six equal
to, that of the shock. Thus, in its nature, and in its time-
relations with the shock, the sound of this after-shock resembled
that which accompanies the typical slight earthquake.

ORIGIN OF THE EARTHQUAKES.

According to the seismic evidence, the mean direction of the
earthquake-fault must be N. 33° E. and $8. 33° W., its hade must be
to the north-west, and the fault must either traverse the village of
Hognaston or pass a short distance to the south-east of it. On the
Geological Survey-map (sheet 72), no faults are marked in the
immediate neighbourhood of this place. The surface-rocks belong to
the Yoredale Series, except for an inlier of Carboniferous Limestone
between Kniveton and Bradbourne, which terminates towards the
west in two masses of toadstone. The faults that border these
masses, according to the Survey-map, were for the most part inserted
to account for the presence of the toadstone. About a mile west of
Hognaston, a few small faults, half a mile or less in length, occur ;
but none agrees, either in direction or position, with the fault
assigned by the seismic conditions. This fault, however, is roughly
parallel to the strike of the neighbouring rocks, and either dies out
before reaching the surface or, more probably, is obscured by the
superficial covering of Drift.

From the phenomena described in the foregoing pages, the
succession of events during the recent disturbances may be clearly
realized. For many years, possibly for more than a century, there
had been no movement of any consequence along the earthquake-
fault. During the previous twenty-four hours, there may have
been a few small creeps, but the evidence on this point is inde-
cisive; and the principal slips took place at 1.30 p.m. on March 24th,
practically without any sensible preparation. It is perhaps worthy
of notice that the Hereford earthquake of 1896 was preceded by
several shocks, originating chiefly in the south-eastern focus; and

232 THE DERBY EARTHQUAKES OF 1903. [May 1904.

that the two slips of the twin-earthquake were not simultaneous,
the earlier and stronger impulse taking place in the north-western
focus. In the Derby earthquake, there was little, if any, preparatory
movement: the two impulses occurred simultaneously, and were
approximately equal in strength. The foci, the centres of which
were about 8 or 9 miles apart, were completely detached, so far as
any sensible movement in the intermediate region was concerned,
and they were probably small in their horizontal dimensions, the
amount of slip becoming rapidly evanescent towards both lateral
margins. On the same day, two other small slips took place, but
their localities are unknown.

An important result of the double slip was a sudden increase of
stress in the regions of the fault-surface within and surrounding
the margins of both foci. The portion of the fault between the
foci, being affected by movements at each end, received the greatest
accession of effective stress, and consequently, on May 3rd, forty days
after the principal disturbance, a minor slip took place chiefly er
entirely within this region, partly perhaps intruding on the nearer
lateral margins of the two foci, and extending upwards to within
a short distance from the surface.

It may be useful, in conclusion, to compare the succession of
movements along the Derbyshire fault with those which have been
the parents of other recent earthquake-series. The first Carlisle
earthquake of July 9th, 1901, was the result of slipsin two principal
foci, the centres of which were about 23 miles apart, and of a
continuous, though less, displacement throughout the whole inter-
mediate region. About 20 minutes later, there followed a slip which
resembled that of May 3rd, 1903, in being complementary to the
principal displacement and affecting the fault-surface between the
two foci.! Again, the Inverness earthquake of September 18th,
1901, was succeeded by several after-shocks, the foci of the more
important of which gradually approached the surface.” A similar
decrease in depth characterized most of the numerous after-shocks
of the great Japanese earthquake of 1891; and, as we have seen,
the focus of the Derby earthquake of May 3rd, 1903, was much
closer to the surface than those of the principal shock. The
materials at our disposal are still too scanty to allow of general
conclusions being drawn. Future shocks may render manifest
other modes of displacement; but I trust that I am not too
sanguine in thinking that the careful study of earthquakes such as
we experience in this country may, in time, reveal to us the laws
according to which faults grow.

EXPLANATION OF PLATE XIX.

Map of the Derby earthquake of March 24th, 1905, on the scale of about
15 miles to the inch.

1 Quart. Journ. Geol. Soe. vol. lviii (1902) pp. 371-76.
2 Ibid. pp. 377-79.

4 td eA Quart. vOUrN, WEOL. HOC, VOL, LA, Ci, ALA.

Wetherby o

-
See Ley ae
ee,
.

Saar cee

oHuddersfield

oseismal 53

re)
Doncaster

ocheffield

seismal 6
(eo)

pelea
.
.

°
Eagle <
Grantham?
(See
* a: SO en ee ° x
| Swadiincote Loughborough oe
Oakham,”
we? >
: : oe: r fg
rmingham oe is
woe O°
: aye Sd
eh
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FAS ee
ad "

ot.

— tr

Bradford, oLeeds

ctham=7 Preston

ws

Southport

oHuddersfield

oseismal 5

ea)
Bolton

Doncaster

Manchester?

Stockport
Ces) oSheffield

o.. ase
Warrington
y]

Chester®. oVicar's Cross

Alsager
5 °
Crewe:

Stafford

oShrewsbury
°Cannock

Wolverhampton?

oBirmingham

oHagley

oBarnt Green

A y
io ive ne gy

a

<

Vol, 60. | THE CAERNARVON EARTHQUAKE OF 1903. 233

17. The Camryarvon Karruauake of June 19rn, 1903, and its
Accessory Snocks. By Cuartes Davison, Sc.D., F.G.S.
(Read June 22nd, 1904.)

[Prats XX— Map.|

I, Inrropvuctton.

Durtye the nineteenth century, the county of Caernaryon was
visited by at least fourteen earthquakes. Seven, if not more, of these
disturbances arrived from distant centres, situated near Pembroke,
Hereford, etc.: but three or four were probably of local origin,
their epicentres being either within or not far from the boundaries
of Caernarvonshire. Ail of these local shocks, however, were of
slight intensity ; and, indeed, within the last five centuries, there
does not seem to have been a single indigenous earthquake that can
be compared either in intensity or in extent of disturbed area with
that which, on June 19th, 1903, was felt over nearly the whole of
Wales, the North-West of England, the Isle of Man, and several of
the eastern counties of Ireland.

In the investigation of this earthquake, I have, as usual, been
assisted by a large number of correspondents, to whom my best
thanks are due. In various ways, I have also received timely aid
from Mr. Edward Greenly, F.G.8., Mr. J. D. Macdonogh of
Bettws-y-Coed, Mr. W.'T. Davies of Nantlle, and Mr. W. A. Thomas
of Llantair-pwllgwyngyll. For lists of after-shocks, the value of
which it would be difficult to overestimate, I am indebted to
Mr. F.C. Carey of Bethesda, Mr. E. Davies of Bodfeirig, Mr. W.
T. Davies of Nantlle, Mr. W. Hughes of Gaerwen, Mr. W. W. Hughes
of Penygroes, and Mr. R. R. Jones of Clynnog.’

The total number of earthquakes belonging to the recent series
may amount to 15 or more, the first occurring on June 19th and
the last on June 23rd. Seven of these depend on the evidence of
more than one observer, and are distinguished below by letters and
detailed descriptions. -The remainder are recorded on the authority
of one person only ; and, although I have been careful to include no
disturbance which did not appear to me to be of seismic origin, it
is advisable, I think, to follow the usual rule, and to regard their
character as earthquakes as not fully established.

IL. Forr-SaHock.

a. June 19th, about 4.25 a.m.

Number of records, 2, from 1 place.

A rumbling noise like thunder was heard at Griffiths Crossing,
near Caernarvon.

1 The cost of the investigation was defrayed from a grant received from the
Government Research Fund.

Q. J.G.8. No. 239. R

234 DR. CHARLES DAVISON ON THE (Aug. 1904,

III. Principat EARTHQUAKE.

6b. June 19th, 10.4 a.m.

Intensity, 7; centre of isoseismal 7, lat. 538° 3"0 N., long. 4° 22:9’ W.
Number of records, 388, from 206 places; and 56 negative records from 44
places,

Time of Occurrence.

The total number of time-records (excluding those which are
confessedly approximate) is 176. Of these, 38 estimates are re-
garded by their observers as accurate to the nearest minute: the
average of 18 such estimates from places within the isoseismal 7
being 10" 8" 3° a.m. As, however, the earthquake was registered
by seismographs at 10" 5” 5° at Bidston, and 10" 5™ 56% at
Birmingham, it would seem that the majority of railway-clocks,
and of others dependent on them, must have been kept about
4 minutes fast, and I have therefore deducted this amount from
the times given for all the shocks.

Isoseismal Lines and Disturbed Area.

The continuous lines in P]. XX, broken in parts where their course
is doubtful, represent the isoseismals 7 and 6, the boundary of the
disturbed area, and those portions of the isesoismals 5 and 4 which
traverse the land. In one or two places, buildings were slightly
damaged. At Clynnog, a slab of slate, weighing more than a
hundredweight, was dislodged from the top of a chimney; and, at
Penygroes, two chimneys were thrown down. Both places are close
to the epicentre of the earthquake.

The isoseismal 7 is an elongated ellipse, 333 miles long, 15 miles
wide, and 420 square miles in area. The centre is situated in
lat. 53° 3'-0 N., long. 4° 22°9' W., that is, 4 miles west of Penygroes
church, and the longer axis runs from N. 40° E. to 8. 40° W. Of
the next isoseismal (6), little more than half can be drawn with any
approach to accuracy ; though the completed curve probably does
not deviate greatly from the path marked by the broken line. The
width of the curve is 38 miles, and its distance from the isoseismal 7
is 11:8 miles on the north-west side, and 10°6 miles on the south-
east. The isoseismal 5 is interrupted by the sea to the north of
Flintshire and in Caerdigan Bay. Its distance from the isoseismal 6
towards the south-east is 20 miles. Of the isoseismal 4, nearly half
can be drawn. It traverses the Isle of Man, and the eastern
counties of Ireland; but its course in the latter district is doubtful.
Its distance from the isoseismal 5 towards the south-east is 27
miles.

The outermost isoseismal drawn corresponds to an intensity
between + and 3. It is 185 miles in length from north-east to
south-west, 173 miles wide, and contains 25,000 square miles. The
shock was also felt at four places outside this line—at Dunmore

Vol. 60. ] CAERNARVON FARTHQUAKE OF 1903. 235

East in County Waterford, Ravensdale in County Louth, Kendal, and
Didsbury (near Manchester). The distances of these places from
the outermost isoseismal are, respectively, 22, 8, 25, and 13 miles.
If we regard the boundary of the disturbed area as passing through
Kendal and as concentric with the isoseismal, the disturbed area
would include about 40,000 square miles. The observations at the
four places mentioned were, however, made in upstair rooms, and,
with one exception, by invalids in bed. It seems desirable, therefore,
to regard the disturbed area as bounded by the outermast isoseismal,
and as containing 25,000 square miles.

Nature of the Shock.

In its general features, the nature of the shock was practically
uniform throughout the disturbed area; and the following account
from Meyllteyrn (near Nevin) may be regarded as typical for a very
large portion of the area. The shock began with a series.of tremors,
lasting 4 or 5 seconds, which merged gradually into a single series
of principal vibrations of about 3 or 4 seconds’ duration, these in
turn being succeeded by a brief series of tremors, lasting only | or
2 seconds. The movement was thus continuous, increased gradually
in intensity, and then rather more rapidly died away. At a few
places not far from the centrai area, two maxima of intensity in
the principal vibrations were detected by careful observers; and
their evidence, as will be seen, is confirmed by the seismographic .
record at Birmingham. At a great distance, at Liverpool and
Southport and in some parts of Ireland, for instance, the vibrations
between these maxima were imperceptible, and the shock seemed
to consist of two detached parts. The period of the vibrations also
increased with the distance, so that, in Lancashire, Ireland, and
elsewhere, the motion was a gentle swaying several times to and
fro. The average of 88 estimates of the duration of the shock is
62 seconds,

Seismographic Records,

The Caernarvon earthquake was recorded by a Milne seismograph
at Bidston, near Birkenhead, and by an Omori horizontal pendulum
at Birmingham.

Bidston is 60 miles from the centre in the direction E, 24° N.
Mr. W. E. Plummer, the director of the observatory, kindly informs
me that the first movements took place at 10° 5™ 5° 4.m. The
separate oscillations of the pendulum are not shown on the diagram,
but there seem, he says, to have been two distinct impulses, the
second taking place at 10" 7" 30°. The amplitude of the dis-
turbance was even less than in the case of the Derby earthquake of
March 24th, 1903.

Birmingham hes 111 miles KE. 20°S. from the centre. The record,
which is enlarged 9°75 times in fig. 1 (p. 236), gives the component
of the motion in the east-and-west direction ; and, as the movement

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Vol. 60.] THE CAERNARVON EARTHQUAKE OF 1903. 237

of the ground is magnified 15:7 times by the pendulum, it follows
that the enlarged diagram represents the actual motion multiplied by
134. The whole movement is divisible, as usual, into three parts—
the preliminary tremors, the principal vibrations, and the concluding
undulations. The preliminary tremors are first perceptible at
10® 5" 56° a.m. (Greenwich mean time), and lasted for 13 seconds.
The enlarged diagram shows hardly any trace of them; but when
the original record is examined under the microscope, they appear
as minute notches, 51 in number, on the tracé. The average period
of the tremors was, therefore, a quarter of a second. The principal
vibrations began at 10" 6" 9°, and lasted 26 seconds. The total
uumber of vibrations is 40 ; but the first 19 are, as a rule, of much
greater amplitude than the rest. They have an average period of
63 second, while that of the remaining 21 vibrations is *67 second.
In the 2nd and 19th vibrations, which are the largest of the
series, the range (or double amplitude) was ‘023 millimetre in the
east-and-west direction, or ‘024 millimetre (that is, about one-
thousandth of an inch) in the direction of the epicentre. Taking
the period of these vibrations as °63 second, the maximum accelera-
tion would be 1°3 mm. per sec. per. sec., or about one-tenth of that
of the Derby earthquake of 1903 at Birmingham. The concluding
undulations began at 10" 6™ 35°. On the enlarged diagram (fig. 1,
p. 236), twenty-seven may be seen, with an average period ot
l second; but, with the aid of the microscope, they can be detected
until 10" 7" 40°, though so obscurely in some parts of the tracc
that their exact number cannot be ascertained. The total duration
of the disturbance was thus 1™ 44°.'

Sound-Phenomena.

The boundary of the sound-area is indicated by the dotted line
in Pl. XX. It is 147 miles long from north-east to south-west,
136 miles wide, and contains about 15,700 square miles, or, say,
three-fifths of the disturbed area. In the whole of the latter area,
88 per cent. of the observers heard the earthquake-sound. In the
central district, the sound was unnoticed by very few persons,
the percentage of audibility being 100 within the isoseismal 7 ;
99 between the isoseismals 7 and 6; 98 between the isoseismals 6
and 5; and falling to 48 in the surrounding zone. The rapid
decline in audibility near the boundary of the sound-area is thus as
marked as it was in the case of the Derby earthquake of 1903.

The number of observers who describe the sound is 291. Of
these, 45 per cent. compare it to passing traction-engines, motor-
cars, etc.; 29 per cent. to thunder; 7 to wind; & to loads of stones
falling ; 1 to the fall of heavy bodies ; 7 to explosicns ; and 3 per cent.

There is no trace of the second impulse registered at Bidston at 105 7™ 305,
At the beginning of the diagram in fig. 1, there is a slight disturbance, which
was, I believe, caused by some particle of dust or roughness of the paper. It
will be noticed that the second half of the more prominent vibrations are super-
posed on a larger curve, which is due to a slight swinging of the pendulum.

238 DR. CHARLES DAVISON ON THE | Aug. 1904,

to miscellaneous types. ‘These approximate closely to the pro-
portions prevalent in strong earthquakes, the average percentages
for the different types in ten recent earthquakes being 46, 22, 10,
4,3, 8, and 6, respectively. ‘The percentage of comparisons to
passing traction-engines is 42 within the isoseismal 7; 49 between
the isoseismals 7 and 6G; and 50 between the isoseismals 6 and 5.
For thunder, ids corresponding percentages are 30, 30, and 24; and,
for wind, 3,.6, and 8: showing how the sound tends to become
smoother and more monotonous with increasing distance from the
epicentre.

The beginning of the sound preceded that of the shock in 62 per
cent. of the records, coincided with it in 36, and followed it in 2,
per cent. The end of the sound preceded that of the shock in
8 per cent., coincided with it in 49, and followed it in 43 per cent.,
of the records. The duration of the sound was greater than that
of the shock in 65 per cent., equal to it in 35, and less than it in
1 per cent., of the records.

Miscellaneous Phenomena.

A few observations were made in slate-quarries in which the
workings are continued underground. At Nantlle, the shock was
felt at a depth of from 50 to 70 yards, the workmen thinking
that a large fall of rock had taken place. It was also noticed in
underground workings at Blaenau Ffestiniog, 19 miles from the
centre.

Among the most interesting observations on the earthquake were
those made on the movement of the loose material of screes. Owing
to the very gradual creeping downwards with every change of
temperature of all stones free to move, a large part of the material
is almost in unstable equilibrium, and a very slight force is necessary
to set it in motion.’ At the time of the earthquake, Mr. W. G.
Fearnsides, F.G.S., was sitting on a slope of serees 150 yards south
of Lleyn dur Arddu and 1 mile north-west of the summit of Snowdon.
‘There were, he says, three chief shocks within about 14 minutes.
The second and strongest so affected the screes that, on turning
round, he saw numbers of stones shuffling and rolling down the
surface. Stones of all sizes were involved, blocks of felsite up to 2 feet
in diameter among them, the larger moving more quickly than the
others, and the noise caused during their motion was so great that
it finally drowned the rumbling of the earthquake. The screes
continued unstable for five minutes, and, at the end of that time,
hundreds of newly-fallen blocks were to be seen lying at the
base.”

" Quart. Journ. Geol. Soc. vol. xliv (1888) pp. 2382-87, 825-26.
- A somewhat similar observation was made at Blaenau Ffestiniog, where
fragments of slate were seen rolling down the ‘ tips’ of waste slate e from the
quarry-workings.

Vol. 60. ] CAERNARVON EARTHQUAKE OF 1903. 239

TY. Arrer-SHocks.

June 19th, 10.7 s.m.: Meyliteyrn.—A very slight tremor, of intensity 3,
accompanied by a sound like that of distant thunder.

Fig. 2.—Map illustrating the area affected by after-
shock £ of June 19th, 1903. (See p. 240.)

Seale of Miles
2 4 6 ;

ewborough

———— ~
—SoNevin

Criccieth
ve

Pwliheliga

[ For ‘ Bettws Garman’ read ‘ Bettws Garmon ’.]

c. June 19th, 10.9 a.m.

Intensity, 3. Number of records, 4, from 4 places.

A slight tremor was felt at Penygroes and at Gaerwen, while a
rumbling sound was heard at the latter place and also at Bethesda

240 DR. CHARLES DAVISON ON THE [ Aug. 1904,

and Bodfeirig. The boundary of the disturbed area and the position
of the epicentre must have coincided nearly with those of the after-
shocks of June 19th, 11.8 a.m. (f) and June 21st, 8.6 a.m. (¢).

d. June 19th, 10.12 a.m.
Intensity, 5. Number of records, 2, from 2 places.

A slight tremor was felt at Penygroes, and a tremulous sound was
heard at Bethesda. ‘The epicentre probably coincided with, or was
not far distant from, that of the preceding after-shock (c).

e. June 19th, 10.16 a.m.

Intensity, 8. Number of records, 2, from 2 places.

A tremulous sound was again heard at Bethesda. At Bettws
Gcarmon, a slight tremor was felt, lasting about 2 seconds, accom-
panied by a sound like very faint distant thunder,

June 19th, 10.23 a.m.: Bethesda.—A tremulous sound.
June 19th, 10.48 a.a.: Penygroes.—A slight tremor.

f. June 19th, 11.8 a.m.

Intensity, 3; epicentre, lat. 538° 7:6’ N., long. 4° 143’ W. Number of
records, 7, from 7 places (fig. 2, p. 239).

The seven places of observation lie within an elliptical area, 20
miles long, 18 miles wide, and 219 square miles in area. The
centre of the area is 8 miles north-east of that of the principal
shock, and the direction of its principal axis N. 47° E. and. 47° W.
A slight tremor was felt at every place, accompanied at Clynnog,
Nantlle, Penygroes, and Gaerwen by a faint rumbling sound,

June 19th, 12.5 p.m. : Bodfeirig.—A slight shock.
June 21st, 5.26 a.m.: Upper Clynnog.—A shock, accompanied by a sound
like that of the tipping of quarry-rubbish.

g. June 21st, 8.6 a.m.
Intensity, 3. Number of records, 5, from 5 places.

The boundary of the disturbed area and the position of the epi-
centre were nearly the same as those of the after-shock on June 19th,
11.8 a.m. (f, fig. 2, p. 239). A slight shock was felt at Nantlle and
Penygroes, and a rumbling sound was heard at Bodfeirig, Clynnog,
and Newborough.

June 21st, about 9.6 a.m : Clynnog.—Sound heard.

June 22nd, 4.26 a.m.: Penygroes—A slight shock, accompanied by a
rumbling noise. A slight shock was also felt at Penllech during the same
morning, but the time is not given.

June 23rd, about 5,31 a.m.: Nantlle.—A very slight shock.

Vol. 60. | CAERNARVON EARTHQUAKE OF 1903. 241

V. ORIGIN oF THE EARTHQUAKES.

rom the seismic evidence, we obtain the following elements for
determining the position of the originating fault :—(1) the mean
direction of the fault must be parallel, or nearly so, to the longer
axis of the isoseismal 7, that is, it must be from N. 40° E. to
S. 40° W.; (2) the hade of the fault must’ be towards the side on
which the isoseismals are farthest apart, or towards the north-
west ; (3) the fault-line must pass a short distance, a few miles at
the most, on the south-east side of the centre of the isoseismal 7 :
so that, in the epicentral district, its course may be submarine, or
it may pass through or near Clynnog or even a mile or two farther
to the south-east; and (+) the fault must be of some magnitude,
extending about 8 miles both to the north-east and south-west of
Clynnog.

On the map of the epicentral district (fig. 2, p. 239), are shown
two faults reduced from the Geological-Survey map (sheets 75 & 78):
one traced for a distance of 14 miles from Aber to Dinlle on
the coast of Caernarvon Bay, the other for 8 or 9 miles from
Bettws Garmon to Clynnog. Of the two, the former satisfies the
seismic conditions more closely. Its average direction is N. 52° KE.
and 8. 52° W., it hades to the north-west, and, according to Ramsay,
the downthrow of the Silurian beds on that side is between 400U
and 5000 feet at Pentir (3 miles south of Bangor), and between
2000 and 3000 feet at Dinas (4 miles farther to the south-west).
If the fault, after leaving Dinlle, is continued under the sea as far
as Nevin, trending rather more to the south, it would occupy
approximately the position assigned to the originating fault. As
no other large fault is known to exist in the epicentral district, it
seems prokable that the Caernarvon earthquake was caused by a
shp along the Aber-Dinlle Fault.

The region of the fault-surface occupied by the seismic focus was
about 16 miles in length, extending from near Nevin to near
Caernarvon; and the amount of displacement was almost uniform
throughout, dying away somewhat rapidly towards both ends.
Though two maxima of intensity were observed at some places, and
were indicated on the seismographic record at Birmingham, there is
no evidence that the focus was discontinuous. The displacement
appears to have been of that simple type to which the great
majority of slight earthquakes owe their origin, and to have been
distinguished only by its great length.

The accessory shocks fall naturally into two classes. The first
includes those, six in number, that were strong enough to attract
the attention of several or many persons; the second includes six
tremors (three of them accompanied by sound) and two earth-
sounds, but all so weak that their occurrence in each case rests on
the evidence of only one observer.

The fault-slips corresponding to the former class were confined to
the north-eastern margin of the principal focus, or to its immediate

242 THE CAERNARVON EARTHQUAKE OF 1903. [ Aug. 1904,

neighbourhood. One of them occurred between five and six hours
before the great displacement, the next four within little more than
an hour afterwards, and the sixth two days later. The last two, if
they were connected with the Aber-Dinlle Fault, originated in foci
quite close to the surface.

If we may assume the disturbances of the second class to have
been of seismic origin, then small sudden creeps, rather than slips,
affected other portions of the fault, one of them occurring at the
south-western end of the principal focus, two at the north-eastern
end, and five in the central region. If, however, the originating
fault were submarine, the weakness of the tremors resulting from
the central and southern slips may be partly due to the greater
distance of the foci.

Denoting slips at the north-eastern end, centre, and south-western
end, by the letters », c, and s, and using capital letters for those
perceived by several or many observers, the distribution of the
different slips in time may be represented as follows :—

June 19th Qist 22nd 28rd
ee ee SS NS ee = eoe_er
IN, principal focus, s, iV, UN, iN, 2, 6, WV, 2, “6° Nj «> Ve" ve

Thus, as in the Japanese earthquake of 189i and the Inverness
earthquake of 1901, seismic action towards the close of the series
was withdrawn from the lateral margins of the principal focus and
was ultimately confined to its central region.

EXPLANATION OF PLATE XX.

Map of the area affected by the principal Caernarvon earthquake of June 19th,
1903, on the seale of 30 miles to the inch.

Discussion.

The Presipentr observed that the Author’s first paper read before
the Society discussed the movements of scree-material. Subse-
quently the Society had welcomed several papers on earthquakes
from his pen; and it was interesting to find that these very different
subjects were both dealt with in the present paper. The Aber-
Dinlle Fault, so far as he recollected, brought rocks of very different
degrees of hardness into apposition along some parts of its course.

Quart. Journ. Geol. Soc. Vol. LX, Pl. XX.

Kendalo

8

Caernarvon

oiChester

Seale of Miles
0-5. Tp ih 20 25 «30; 35 40
EE EE ee ee ee Ee Se ee |

AERNARVON HARTHQUAKE OF JUNE 197TH, 1903.

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Map or THe AREA AFFECTED BY THE PRINCIPAL CAWRNARVON BARTHQUAKE OF JUNE 197TH, 1903.

Vol.60.] | EOCENE, ETC. SURROUNDING THE DARDANELLES. 243

18. Eocene and Laver ForMArions SURROUNDING THE DARDANELLES.
By Lieut.-Col. Tuomas Enentsu, late R.E., F.G.8. (Read
February 24th, 1904.)

[Prares XXI-XXTIT. |

ConTENTS.
Page
Pe Ereiocene es OFMALIONS.... 6.6.0: ise sacvecttavastnde see? 243
eee MON LE UIATL 8.602). 5 «5 vas. -)scdenuseue sess mgacmnaeeanaee 244
AIT. Uppermost Eocene and Oligocene ................... 246
DV Sa Wel POPUIALY HOIGIEOS .......6.05.0000sesermdpees tenance 250
Wl omumby. V Olcantic HOCKS 05... . 6.00. och aetaee ewe ones 252
Vllehy Le MES As i ne ne ree Pc 255
OE 2 Bry ee ea A oe 261
ULL ACS DCE oS Oe i ea ier Een ae 265
EX) Summary Gf ONservations....0<...... 56. 500:00 ds. dadesageee 272
a TRIUOAT ADORE RI RUSE oo. ..:., .ccnccsssencacsecnscomayaet acs 274

I. Pre-Eocenr ForMArIONsS.

A puscrivrion of the Tertiary and post-Tertiary deposits surrounding
the Dardanelles can hardly be made clear without some reference
to the older rocks upon which they rest, but our knowledge of the
conditions under which the pre-Eocene strata in Thrace and Anatolia
were deposited and broken up is as yet very limited.

The pre-Eocene sedimentary formations are, as a rule, so highly
metamorphosed that no fossils are visible; and they are so much
dislocated that the general appearance is that of an archipelago of
old rocks in the Eocene Sea. A succession of mica- and hornblende-
schists, crystalline limestones, and marble, with occasional gneiss
or granite and serpentine, upon which the Tertiary deposits rest
uncontformably, can be traced from Olympus and Athos, along the
Thracian coast, including the island of Thasos, into the Sea of
Marmora. ‘The Eocene shore-lines and fringing coral-reefs can be
identified in some instances, but an inspection of the map (Pl. XXI)
will show the probable islands of the pre-Eocene archipelago more
clearly than any description. I shall, therefore, only refer to a few
localities hitherto unnoticed, or where some correction to previous
accounts appears to be necessary.

At Tenedos Island I found the south-eastern face for about
2 miles in length, from Cape Marmora to Oinos Point, to be formed
of white marble.

Along the southern shore of the Sea of Marmora, a
stretch of about 35 miles, from Boz Burnu to Kara Burnu, and
thence halfway up the Gulf of Artaki, shows, from west to east,
granite, schist, diorite, marble, and granite.

At Pasha Liman Island, 13 miles east of Kara Burnu, the
lowest rock visible at the south-western point is marble, and there is
an exposure of schists for a mile in length along the western shore,

244 COL. I. ENGLISH ON THE EOCENE AND [ Aug. 1904,

with a steep northerly dip. Spratt (1, p. 218) terms this island
‘volcanic,’ but near the sea-level I could find no trace of volcanic
action.

The neighbouring islands of Kutali and Afizia show schists,
granite, and syenite.

In the adjacent Artaki Peninsula marble appears near the
sea-level, covered by epidote-hornblende-schists, and diorite with
hornblende, with a steep northerly dip at the north-western
extremity, Palios Point. At Murad Bair (near Artaki town), on
the south side of the peninsula, schists and marbles are exposed
with a varying dip.

Marmora Island, separated from the Artaki Peninsula by a
channel 5 miles wide and 30 fathoms deep, is similarly formed of
alternating marble, schist, syenite, and marble, dipping steeply north-
westward.

The Devonian rocks of the Bosphorus, 120 nautical miles east-
north-east from the Dardanelles, have long been known. Their
south-western limit is usually, following F. von Hochstetter, stated
to be the Golden Horn, and Stambul is supposed to be built on
Miocene deposits (2, p. 373); but there is an outcrop, in the
railway-cutting at Old Seraglio Point, of steeply-inclined brown
schistose rocks, which are, to all appearance, older than Miocene,
and may probably be Devonian: they dip about 60° southward.

The southernmost visible extension of Devonian rocks is at the
Deserters’ Islands, off Tuzla Burnu.

For the reasons already assigned, I do not propose to enter into
any discussion of pre-Eocene foldings, and I have selected the
Eocene deposits as the starting-point of a more detailed description
of the tectonic phenomena, because they can be traced throughout
the whole district, and are perhaps more readily to be identified
than any other of the formations which are exposed thercin.

IJ. Kocenn (Lorerran).

The Eocene deposits surrounding the older rocks begin with
sandstones, conglomerates, and clays, which become calcareous and
hummulitic upwards, and then change again to unfossiliferous
sandstones and shales, with subordinate lacustrine beds. ‘These
strata are much disturbed and faulted, and are often vertical.

I have seen a section between Yenikeui and Sarkeui, on the
northern shore of the Sea of Marmora, in which hard coralline
limestone, highly metamorphosed, hes conformably upon bands of
rough conglomerate, containing pebbles of old rocks, and sandstones.
These, again, overlie purple and grey clays, the whole dipping 70°
north-westward. Similar sections exist west of Demotika and at
Bektashhi in Thrace (3, pp. 344, 351); also at Kara Deré on the
southeru shore of the Sea of Marmora (4, p. 18).

* Numerals in parentheses throughout this paper refer to the Bibliographical

List on p. 274.

Vol. 60.] LATER FORMATIONS SURROUNDING THE DARDANELLES. 245

In other places, however, Nummulitic Limestones lie directly
upon the older rocks without the intervention of any sandstones,
conglomerates, or clay. Prof. R. Hernes says that in Samothrake
they rest immediately upon old clay-slates (5, p. 9); and F. von
Hochstetter remarks that at Sarai, Wisa, and Kirk-kilissé in the
north, they lie directly upon the gneiss, also that there is most clearly
a similar sequence in the Tundscha defile (2, pp. 383, 390, 392).

Viquesnel gives a section at Balouk-keui, near Feredjik in
Thrace, of red and green clays, with bones, and of greenish sandstone
resting unconformably on ‘terrains de transition’; then
sandy limestones with freshwater shells, Viguesnelia lenticularis
and Paludina ; and at the top, calcareous, possibly Nummulitic sand-
stone (grés calcarifere a nummulites?), with Nerinea, Pecten,
large Turritella, and club-like corals (3, p. 331). A. d’Archiac, in his
identification of the bones from this section as those of a Rhinoceros
of indeterminate species, classifies them as belonging to the Middle
or Upper Tertiary fauna, but is evidently at a loss to explain
the occurrence of Nummulitic deposits above them (3, p. 470).
I examined the beds at Balouk-keui, but unfortunately without
knowledge (at the time) of Viquesnel’s description, so that I cannot
be sure whether it was the same exposure which I saw; the upper
beds appeared to me to be distinctly Miocene, and they certainly
include naphtha-sands.

F.von Hochstetter, relying principally upon Viquesnel’s description
of this section, has concluded that there is a lower division of the
Eocene in this region, with a partly-lacustrine facies, under the
purely-marine Nummulitic Limestone-Series. He goes on to say
that he can scarcely find another place for the coal-seams known in
Thrace, at the time at which he wrote, than this lower lacustrine
division of the Eocene (2, p. 450). This, in my opinion, is certainly
erroneous, and the mistake probably arose from his classification of
_ the Oligocene strata, in which the coals reaily occur, as Primary
rocks (phy llit).

There is a section, found by Mr. White (the engineer to the
Keshan Collieries), running north and south along the Gorgona
Valley near Sarkeui, on the northern shore of the Sea of Marmora,
in which the outcropping edges of vertical and steeply-inclined
Nummulitic strata are exposed for more than half a mile, nearly at
right angles to the strike. The section continues southward for
about the same distance across the edges ot the lacustrine sandstones,
clays, and shales, which are interbedded with the upper portion of,
and then overlie, the Nummulitic Series. The measured details of
this exposure are given in Table II (p. 273), but the conditions of
the ground leave it uncertain whether the section represents only the
actual thickness of the Nummulitic Series, or whether the beds are
repeated by folding or faulting. If, as I believe, they are not so
repeated, the Nummulitic Series here cannot be less than 2000 feet
thick.

246 COL, T. ENGLISH ON THE EOCENE AND [ Aug. 1904,

Nummulitic deposits have been found in Samothrake (5, p. 9),
along the whole length of the Eocene coast-line in Thrace (3, passim),
at Vernitza,and at Teke, near Keshan (on the north side of the Gulf
of Xeros), and from Bournar Oren to Mount Elias, along the northern
shore of the Sea of Marmora. They appear also on the southern
shore of that sea at Kara Deré, west of Gueredjé, and nearly opposite
to Gallipoli (4, p. 18), and at Korou, south of Lampsaki.! The
foraminifera and other fossils collected from the Nummulitic
(Lutetian) Limestones of Vernitza and Mount Elias are described in
Appendices IT & III (pp. 288, 292),

Coralline limestones, generally harder than the Nummulitic
deposits, are frequently interstratified with them, as at Vernitza ;
and also occur separately at Saraiyik, about 4 miles east of Chanak
in the Dardanelles, and at numerous localities in Thrace.

Prof. L. de Launay (6, p. 244 & map), following Tchihatcheff (7,
vol. iii, pp. 172 et segg.), but with some reserve, shows in his
geological map, as unfossiliferous Eocene, a great belt of country
some 50 miles wide, bounded on the north by the Marmora shore
from the Gulf of Artaki to Guemlek, and sweeping round to the
south-west untilit meets the sea, from Adramyti nearly to Smyrna.

III. Uprermost Eocene and OLIGOCENE.

Immediately overlying the Nummulitic rocks is a succession,
about 3000 feet thick, of lacustrine sandstones, clays, and shales,
interstratified with volcanic rocks and containing coal-seams.
These strata represent the uppermost Eocene and the Oligocene,
and the coal-seams belong to the latter formation. They are
widespread in Southern Thrace, and are cut off to the eastward
by the falling-in of the Marmora sea-bed. They extend along
the Gallipoli Peninsula to the islands of Imbros and Lemnos, and
possibly tarther southward to Psara and Eubeea.

In the paper which I had the honour of reading before this
Society in December 1901 (9, pp. 153-55), I described the coal-
basin near Keshan, the only one the limits of which had then
been partly traced. Since that time, the existence of the same
principal seam has been proved at a number of points, notably at
Masatly and Harmanly, about 17 miles north of Keshan. The
Keshan coal-basin has also been traced eastward for about 12 miles
to a point south of Malgara, and there is every reason to believe
that it extends yet farther eastward in the direction of Rodosto,
and westward across the Maritza River.

The evidence of its age is as follows :—A lower jaw and teeth,
included in the coal itself, and now at the British Museum, were
discovered at Masatly, and have been identified as Anthracotherium,
nearly related to A. minus.

There are innumerable impressions of leaves distributed through
the sandstones and clays, yet in only one case have they been found
in a recognizable condition. Prof. Toula, in 1895, found plant-

1 Communication to the Author from Mr, F. Calvert.

Vol. 60.] LATER FORMATIONS SURROUNDING THE DARDANELLES. 24/7

' remains on the southern shore of the Sea of Marmora, between
Lampsaki and Gueredjé (4, pp. 19-20), which were pronounced by
Dr. Fritz Kerner von Marilaun to be ferns, agreeing well with
Chrysodium (Fortisia) Lanzceeanum from Monte Promina, and from
the Lower Bagshot of Studland, the Middle Bagshot of Bourne-
mouth, and the Upper Eocene of Hordwell; also nearly identical
with Oligocene forms from the gypsum of Aix and from the Aqui-
tanian of Manosque (8, p. 26 & pls. 1-11). He moreover identified
Sterculia Labrusca, fan-palm, oak, and laurel-leaves, and considered
the beds to be not older than Middle Eocene, but not younger
than Oligocene. These plant-remains occur between Kara Deré
and Boz Burnu, in two marl-beds, in a series of sandstones with
layers of conglomerate and slaty marl, dipping 45° north-north-
westward.

At Keshan, about 40 feet above the coal, and immediately under
the band of brecciated andesite which covers it, there is a thin
fossiliferous seam in the sandstones, traceable for about a mile and
a half, containing abundant casts of Corbicula (Cyrena) semistriata
and Melanopsis aff. M. fusiformis, accompanied by indeterminable
plant-impressions. At Lalakeui, 8 miles north of Keshan, the sand-
stones contain leaf-impressions and Corbicula semistriata, which has
also been found in the coal at Masatly. Samples of soft shelly lime-
stone, found at Harmanly, 3 miles east of Masatly, contain Corbicula
semistriata and Melanopsis, with small fragments of lignite.

Three miles inland from Hora, on the nor hesn ices of the Sea of
Marmora, a boring, started in the naphtha-bearing Miocene deposits
at 400 feet above sea-level, struck the fault which cuts off the
Lower Tertiary sandstones here (9, p. 152), at about 270 feet from
the surface. The boring was continued in hard sandstones and
shales, with a very steep dip, to a depth of 1149 feet, and specimens
of (probably) Corbicula semistriata were brought up from between
1043 and 1066 feet.

Mr. White has measured a section through the Keshan sand-
stones, of which the details are set forth in Table III (p. 274), with
the result that there are at least 1230 feet of blue shales and
sandstones above the coal, and 1350 feet of brown and grey sand-
stones (with occasional shales) below the coal, before any Nummulitic
rocks appear. ‘This section agrees very fairly with the upward
continuation of the section at Gorgona Deré and Sarkeui, distant
25 miles south-east by east (see Table EY. -pe 27a where, for a
horizontal distance of 3600 feet to the southward of the highest
Nummulitic stratum yet recognized, there are vertical and
steeply-inclined brown sandstones and shales, overlain by green
sandstones and clays, containing seams of lignite and_leaf-
impressions,

On the northern shore of the Sea of Marmora, with possible
exceptions in small outcrops between Buyuk Tchekmedjé and Silivri,
these lacustrine sandstones and clays only reach the sea between
Ganos and Combos, where they form the high coast-cliffs of the
Tekfur Dagh, and have been cut off to the eastward by the fault

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Vol. 60.] | EOCENE, ETC. SURROUNDING THE DARDANELLES. 249

bordering the falling-in of the Marmora sea-bed. The general
appearance of the strata is shown in fig. | (p. 248), reproduced
from a photograph taken at a point near to which the soundings
show an average gradient of 1 in 3 from the foot of the cliffs
down to a depth of 580 fathoms.

On the south of the Sea of Marmora, coal-seams, clays, and
shales interstratified with andesite, occur near Tchatal Tepé, south of
Kamir. The principal seam consists of bright, bituminous coal,
similar in quality to that found at Keshan, 18 inches thick, with
a clay-floor and roof.

Since writing my previous paper, I have had an opportunity of
tracing these lacustrine deposits westward from the neighbourhood
of Examil, on the isthmus between the Gulf of Xeros and the Sea
of Marmora, where they are overlain by Miocene strata. They
appear again between Bulair and Yeni-keui, on the northern coast
of the Gallipoli Peninsula, and form the whole of this coast as
far as Cape Suvla, a distance of 25 miles, considerably disturbed in
places, and with a generally-steep south-south-easterly dip. The
coast-cliffs are apparently cut off all the way by a fault with a
north-north-westerly downthrow, and plunge immediately into the
deep water of the Gulf of Xeros. These strata form the backbone
of the Gallipoli Peninsula, and the harder rocks rise in places to
an altitude of 1300 feet. South-eastward they are overlain un-
conformably by the generally-horizontal Miocene sands and clays
which enclose the Dardanelles, the line of demarcation following
approximately the centre-line ‘of the peninsula. Seams of coal
occur at several places in the sandstones, between Buyuk and
Kutchuk Hanafart, at Taifur-keui and Kavakly.

Similar sandstones, also with thin seams of coal, reappear in
the north-eastern quarter of Lmbros, which is separated from Cape
Suvla by a channel 13 miles wide and 50 fathoms deep. They con-
tinue to show along its northern coast, until they are hidden by the
volcanic rocks which make up the main bulk of theisland. The
sandstones, with subordinate shales and clays, come into contact
with andesite about a mile south of the village of Panagia, where
they dip 30° eastward. A thin lignite-parting shows in the sand-
stones about half a mile south of Panagia. Ata mile and a half
north-east of the village, some small excavations have been made, in
order to ascertain the development of a coal-seam about 6 inches
thick, which crops out here between clay-beds. There are some
old coal-workings about 4 miles north-east of this locality, and coal
is said to crop out some miles to the west. The sandstones are
indistinguishable from those of Keshan, and the appearance of the
coals is also very similar.

In Lemnos, according to Prof. L. de Launay’s description, the
sedimentary rocks are composed exclusively of sandstones, grau-
wackés, conglomerates, and shales, without limestones, and occupy
more than two-thirds of the island, often showing traces of meta-
morphism. ‘These deposits are generally dark in colour, from brown
to green, and of very compact, fine-grained texture. with no traces

Q.J.G.8. No. 239. s

250 COL. T. ENGLISH ON THE EOCENE AND [Aug. 1904,

of organic life except indistinguishable plant-remains, generally
with very steep dips, and occasionally with reversed beds (6, p. 201).
This description might be applied, word for word, to the bulk of
the coal-bearing strata on the mainland and in Imbros.

Prof. de Launay supposes that the Lemnos rocks represent a sort
of ‘ flysch,’ either supra-Cretaceous or Eocene, and that the solution
of the question of their age may be furnished by an examination of
Imbros (6, p. 208). He evidently inclines to a supra-Cretaceous date
(6, p. 198), but perhaps the Kocene or Oligocene alternative would
have had more weight with him, had he been in possession of the
information from Imbros and the Gallipoli Peninsula which I have
had the opportunity of obtaining.

Prof. Hoernes describes, in Samothrake, above black Nummu-
litic and echinoidal limestones, a series of alternate layers of sand,
sandstone, and conglomerate, between which more or less thick
strata of greenish-blue and red to blackish-brown volcanic tutfs are
intercalated. This series includes a great part of the island, and is
surmounted by trachytes (9, p. 9).

From the abundance of Corbicula semistriata it is certain that
the coal-seams in the Dardanelles district are Oligo-
cene. All the available evidence points to the conclusion that
the strata of Lemnos, north-eastern Imbros, the southern shore of
the Gulf of Xeros, the Kuru Dagh and Tekfur Dagh in Thrace, a
great part of Samothrake, and the beds described by Prof. Toula at
Gueredjé and by myself at Tchatal Tepé (on the south side of the
Sea of Marmora), belong to the same lacustrine formation above
the Nummulitic (Lutetian) Limestones. As in the Carpathian Sand-
stones in Western Rumania, this formation appears to represent
both the uppermost Eocene and the Oligocene (10, p.79).

Farther south in the Archipelago, the evidence is more conflicting,
but, according to Prof. de Lapparent, the flora of the basin of
Kumi, in Eubeea, belongs to the Aquitanian division of the Oligo-
cene (11, p. 1509). In the island of Skyro, and in Chelidromia,
one of the Magnesian group, Prof. Philippson notices lignite-deposits,
which he considers to be equivalent to those of Kumi. He also
remarks black and yellowish clay-slates, sandstones, and limestones
above the Cretaceous, in the islands of Skiatho, Skopelo, and
Chelidromia (12, pp. 117, 127, 1380, 136). The eastern coast of
Psara, 35 miles south-south-west from the western point of Mitylene,
consists of a series of dark-blue and grey shales, interstratified
with occasional beds of yellow and reddish sandstones, all showing
a general dip of 30° to 40° south-eastward. These beds apparently
extend nearly, if not quite, to the highest point of the island.
I could see no appearance of volcanic rocks from the sea.

TV. Lower Terrrary Foipres.

Throughout the whole district surrounding the Dardanelles, the
general folding of the Lower Tertiary strata, both Nummulitic and

Vol. 60.] LATER FORMATIONS SURROUNDING THE DARDANELLES. 251

lacustrine, is very plainly developed, and follows a north-east-by-
easterly direction through the Eocene channel between the old rocks
of Thrace and those of the Troad. The central fold can be traced.
in nearly a straight line north 60° east, for 200 miles from the
islands of Skiatho and Skopelo in the Magnesian group, through
Lemnos, Imbros, and the north-western coast of the Gallipoli Penin-
sula, until abreast of Ibridji, in the Gulf of Xeros. This direction
of folding of the Lower Tertiary strata accords with that shown
by Prof. Philippson (14, map) for the ‘fiysch’ of Thessaly, which
is described by Hilber as Oligocene and as containing coal-seams
(13, p. 621).

F. von Hochstetter considered that the higher ridges of the
Gallipoli Peninsula consist probably of clay-slate (phyillit), and
that the Nummulitic Limestone in Thrace lies generally horizontal,
showing only local disturbances (2, pp. 389, 409). These con-
clusions are not borne out by the facts which I have observed:
the Nummulitiec and Oligocene rocks are dislocated
and folded on a large scale, and form basins in which
the Helvetian and later deposits were laid down.

The Lower Tertiary lake had a coast-line in Thrace little differing
from that of the Nummulitic sea, but probably transgressing some-
what more in places over the older rocks; as, for example, in the
south-eastern part of Samothrake, where the sandstones and volcanic
tuffs le directly upon old clay-slates (5, p. 11). Its waters
reached certainly to Lemnos in the west, and to Rodosto in the
east, possibly even farther eastward, as Viquesnel mentions sand-
stones with carbonized plant-impressions from Buyuk Tchekmedjé
to Silivri, on the northern shore of the Sea of Marmora
(3, p. 310).

A reference to Pls. XXI & XXII will show that the strikes and
dips of the Lower Tertiary strata surrounding the Dardanelles
result from three main foldings, of which the northernmost
intersects the island of Samothrake, where the Nummulitic strata dip
north-westward and westward in the western portion of the island,
and eastward in the south-eastern corner. This fold forms the
eastern portion of the northern boundary of the North A®gean
depression ; thence, passing inland, it shows in the anticlinal ridge
of the Kuru Dagh. It is continued, through the Tekfur-Dagh ridge,
nearly to Rodosto, and thence eastward forms the northern boundary
of the Marmora depression. Fig. 2 (p. 252) shows the appearance
of the vertical Oligocene strata at Combos near Rodosto, with the
horizontal Miocene terraces overlying them unconformably.

The folding which follows the southern shore-line of the
Eocene channel between Thrace and the Troad enters the district
in a nearly north-and-south line at Mitylene (16, p. 428), passes
through the Troad in a north-north-easterly direction, curving
north-eastward, and skirts the old rocks at Gueredjé, where the
Lower Tertiary lacustrine deposits dip 45° north-north-westward.
From this place it runs as a fault with a north-north-westerly
downthrow along the southern shore of the Sea of Marmora, past

s2

252 COL, T. ENGLISH ON THE EOCENE AND [ Aug. 1904,

Kara Burnu, skirts Marmora Island, and, turning eastward, forms
the southern border of the Marmora depression.

Along the central fold the beds dip north-north-westward at
Skopelo Island (12, p. 130): in Lemnos they dip north-north-
westward towards the North A<gean depression, and south-south-
eastward towards Mitylene; in north-eastern Imbros they dip
eastward; and along the coast of the Gallipoli Peninsula, from
Cape Suvla to opposite Gallipoli, they dip south-south-eastward.
A much later development of this fold (Pl. XXII, fig. 2) has given

Fig. 2.— Vertical Oligocene strata at Combos, unconformably
overlain by horizontal Miocene terraces. (See p. 281.)

rise to the ridge of Dohan Aslan and Serian Tepé, and has dislocated
the Sarmatic Beds to the eastward as far as Ganos, by a fault with
a south-easterly downthrow.

There is not, as yet, sufficient information available to determine
the positions of the subsidiary foldings dependent on the changes of
direction of the main folds, but there are indications of one running
about north 30° west through the islands of Tenedos, Imbros, and
Samothrake, and of another in a nearly due northerly direction
through Ibridji, passing west of Keshan.

V. Tertiary Votcanic Rocks.

The volcanic eruptions in this district were prolonged, apparently
without much interruption, from Cretaceous times into the Miocene
Period, but a more detailed study than has yet been made will be
required to determine the periods of action of the respective volcanic

Vol. 60.| LATER FORMATIONS SURROUNDING THE DARDANELLES. 293

' foci. In Imbros, however, a date later than Oligocene and earlier
than Sarmatic can be assigned to the andesite-flows in the south-
eastern portion of the island.

At Keshan, the interstratification of Lower Tertiary sandstones
with andesite is distinctly visible. A section on the south side
of the Keshan ridge, which rises about 1000 feet from the plain.
shows, from below upward: shale and sandstone, about 40 feet of
andesite, 300 feet of sandstone, 30 feet of volcanic rock (probably
andesite), 200 feet of sandstone, and a coping of volcanic rock.
This section is exposed in a small ravine at Tekekeui, where there
are unaltered sandstones overlying the andesite, and within 2 feet
of the solid rock; while under the andesite, similar sandstones and
fine shales are equally unaltered, even close to the contact-surface.
The andesites and sandstones have the normal dip of the sur-
rounding strata, that is, about 10° north-north-eastward.

In Lemnos, Prof. L. de Launay has observed quartz-andesites,
dacites, trachyandesites, and augitic andesites; he con-
siders them to be perhaps Miocene, certainly later than the sand-
stones which they have dislocated and intersected (6, pp. 209, 219).

At Hagio-Strati Island, 20 miles south-south-west of Lemnos,
I found nothing but hornblende-andesite at the sea-level.
This island is about 1000 feet high, rugged and trackless: it
seemed to me to be a uniform mass of voleanic rock, without any
appearance of Tertiary sedimentaries (see Appendix I, p. 277).

On Imbros I found that the whole south-eastern face of the
island, exclusive of the promontory of Megalai Kephalai, which is
virtually separated from it by a salt-lagoon enclosed by sand-ridges,
consists of grey and dark-red andesite, weathering into rounded
lumps, and forming a red soil between them. Following the valley
of Melano Potamo north-westward to the watershed, I found an
exposure of biotite-augite-andesite, differing considerably
in external appearance from the surrounding rocks, and splitting
into rectangular vertical prisms which resist weathering; its petro-
logical character is also peculiar (see Appendix I, p. 277). The
track passes for 3 or 4+ miles over andesite, with occasional
obsidian-dykes, and well-defined flows of what must have been
semi-fluid material, which have curled over and now form large
caves. At the watershed, the track skirts a breccia with a matrix
of hardened volcanic mud. Fragmerts of porcellanite are
abundant, but the main mass, on both sides of the watershed, is
andesite, shown in fig. 3 (p. 254). The higher hills to the south-
west are apparently volcanic, and include several isolated domes.

At the head of the Gulf of Xeros are several small outcrops of
voleanic rock, generally hornblende-andesite, on the synclinal
fold of the lacustrine sandstone-strata, and in one of these, at
Xero Mikro Island, I found schists lying horizontally under volcanic
rock.

At Enos there is a large volcanic mass, forming a detached boss
about 1300 feet high, and roughly 6 miles in diameter: Viquesnel
describes it as formed of trachyte and domite (3, p. 326); and

254 COL. IT. ENGLISH ON THE EOCENE AND [Aug. 1904,

he characterizes the volcanic rocks in the Maritza and Arda Valleys
generally as trachytes and tuffs.

There are numerous volcanic outcrops in the near neighbourhood
of Keshan, including brecciated rhyolite and andesite,
olivine-basalt, hornblende- and biotite-andesite (see
Appendix I, p. 277).

A small outcrop of basalt is exposed 3 miles north of Rodosto,
and another about 12 miles north-east of this (3, p.312); a detailed
survey of the country would no doubt reveal many similar exposures.

In Asia Minor are very many outcrops, sporadic and in belts,
in the country east of the Troad, which Ichihatcheff generally
classes as trachyte and basalt (7, passim).

Fig. 3.—The andesitic hills of Imbros, with a distant view of
Megalai Kephalat (Sarmatic). (See pp. 254, 259.)

South of Kamir, on the southern shore of the Sea of Marmora,
decomposed andesite or rhyolite and volcanic mudstone
appear at Arsali, silicified andesitic or rhyolitic tuffs
at Pekmeslu, and hornblende-andesites at Tchatal Tepé,
interstratified with Oligocene rocks.

In the Southern 'Troad, Mr Diller has given particulars of
liparites, mica- and hornblende-andesites, augite-
andesite, and basalt, and considers that the eruptions have
continued from Eocene to Pliocene times. He also notices a well-
marked eruptive centre at Assos (Behram Keui), not older than
Middle Tertiary (17, Prelim. Report, p. 179).

In Mitylene, Prof. de Launay reports a more varied series than
at Lemnos, and considers that the following is the most prob-
able order of succession:—felspathie trachyte, rhyolitic

Vol. 60,] LATER FORMATIONS SURROUNDING THE DARDANELLES. 259

trachyte, dacite, trachyandesite, hornblende- and
augite-andesite, labradorite, and basalt (6, pp. 184—85).

In Tenedos, Spratt describes the north-eastern point of the island
as ‘trachyte’(1, p.214). Lfound that there is also an exposure of
volcanic rock along more than half of the eastern coast, extending
farther south than Tar Point.

In the valleys of the Scamander (Men Deré) and of the Thym-
brius (Kemer Deré), Mr. Calvert found basalts between Bali Dagh
and Akché Keui, in the form of coulées flowing from the crystalline
marble and serpentine-hills, and covering and indurating the débris
at their feet. At the White Cliffs, below Chanak in the Dardanelles,
he also found the red clays and calcareous beds much disturbed
and altered by an outburst of voleanic rock." A specimen of this
rock has been identified as an unusual variety of biotite-andesite
(see Appendix I, p. 276).

The Tertiary voleanic rocks show a marked tendency to appear
along the coasts of the Eocene Sea, and in long belts following the
strikes of the foldings of the Lower Tertiary strata.

The widespread late Kocene and Oligocene volcanic rocks would
certainly seem to imply considerable differences in the relief of the
land, at the time at which they were ejected; and it is difficult to
reconcile this with the equally widespread coal-seams, presumably
requiring shallow lakes or marshy country with only slight
differences of level.

VJ. Miocene.

i propose to demonstrate the existence of Helvetian-
Tortonian deposits, probably vestiges of a Lower
Miocene sea-connection between the Ponto-Caspian
and the Mediterranean. These are overlain by fresh-
water Sarmatic strata with Jignites and naphtha, suc-
ceeded by marine (Wactra-) limestones, which occupy
nearly the whole of the northern shore of the Sea of Marmora, to
the exclusion of the Levantine Beds, suggested by F. von Hochstetter
(2, map) as filling up this area. These Mactra-limestones are in
direct continuation of those already known in the Southern Troad
and in the Dardanelles. There is also evidence of the occurrence
of Sarmatic strata in Imbros and in Tenedos.

At Eregli, on the northern shore of the Gulf of Xeros, and thence
several miles inland to Fakirma, occurs an exposure of sands and
sandy limestones, with a slight southerly dip. These beds, close to
the present sea-level at Eregli, contain typical Helvetian-Tortonian
fossils—Pecten aduncus, Alectryonia Virleti, and Anadara diluvii,
also Ostrea lamellosa, of Which specimens are now in the British
‘Museum (Natural History): see Appendix II, p. 285. Prof. Suess
says that, from a large number of measurements, he has arrived
at the conclusion that the shore-line at this epoch was 440 to
450 metres above the existing level of the sea (15, pp. 412-13);
and the Eregli beds probably owe their preservation to the fact of

! Communication to the Author,

256 COL. T. ENGLISH ON THE EOCENE AND [ Aug. 1904,

their having been deposited at a point where a further development
of synclinal folding subsequently took place.

Near Myriophy to, on the northern shore of the Sea of Marmora,
a band, full of Ostrea crassissima (Appendix II, p. 285), occurs under
soft yellow sand, dipping about 45° south-south-eastward, at a height
of 700 feet above the sea. Below the oyster-band are soft shales,
resting upon quartz-conglomerate. ‘The whole of this series has
been thrown down by the fault which extends from Mount Elias to
Ganos, and abuts on the nearly-vertical Lower Tertiary shales and
sandstones (9, p. 152).

Strata of similar age have been found to the north at Varna and
at Cape Tchokrak in the Kertch Peninsula (18, p. 190, and 24,
Table of Beds below the Sarmatic, p. 7), and to the south at Savakly
in the Troad (Fischer, 7, pp. 259 et seqq.); and at Kasos Island
(19, map), and in Thessaly and Macedonia (16, p. 431).

The Eregli and Myriophyto Lower Miocene marine shell-beds
thus form links in a chain of deposits of the same age, extending
from the Crimea to the Mediterranean, and the most obvious
explanation is that they are detached fragments of what
was a continuous sea-bed.

Between the deposition of these beds and that of the lacustrine
and marine Sarmatic strata which succeeded them, the folding
must have developed considerably, perhaps to the extent shown
in fig. 1, Pl. XXII, which indicates the main anticlines of the
Eocene and Oligocene Series, and a possible coast-line of the Sarmatic
and Pontian basins. ‘.

The connection with the Sarmatic sea probably developed from
the outflow of a lake, with a narrow opening to the north-east
between the Eocene deposits near Derkos on the Black-Sea coast (see
Pl. XXI). From here the shore-line swept round the southern
portion of the Sea of Marmora, skirting Marmora Island, and tke
serpentines and schists, voleanic and Eocene strata in the Troad,
against which Mr. Calvert has noticed the Sarmatic strata to thin
out at Dumbrek in the Kemer Deré, and at Belenkeui.’

A deep gulf, directed north-east and south-west, included the
Dardanelles and part of Tenedos, and terminated near Mitylene.
Its north-western shore skirted the south-east of Imbros and
the Oligocene lacustrine sandstones of the Thracian Chersonese,
which then formed a long peninsula in the opposite direction to the
present one, terminating: between Yenikeui and Bulair, where
the Sarmatic Beds cross the present isthmus between this point
and the Oligocene sandstones near Examil, in what was a channel
about 8 miles wide. The waterway was subsequently blocked by
the elevation, due to further folding, of the Dohan-Aslan ridge,
which is thrown up diagonally across it, and has tilted the
bituminous Sarmatic Beds on its southern slope, where they can be
seen dipping 50° south-eastward.

This channel formed a connection with an internal Sarmatic

1 Communication to the Autaor.

Vol. 60.] LATER FORMATIONS SURROUNDING THE DARDANELLES, 257

basin, traces of which can be found stretching across the Chalkidike
Peninsula to Kassandra (20).

As, however, nearly the whole possible area of this basin is now
covered by water, its limits cannot be defined farther than that it
did not extend beyond the northern coasts of Lemnos and Athos, and
the southern coasts of Thasos and Samothrake. ‘The last-mentioned
island was probably then connected with the mainland, as it stands
on a broad bank of soundings, on which the depths do not exceed
30 fathoms.

Eastward of this, the Oligocene rocks of the Kuru Dagh and the
Tekfur Dagh formed a large tract of land, into which a Sarmatic
gulf extended for some miles beyond the head of the present Gulf
of Xeros. The ridge of Serian Tepé, though not so markedly de-
veloped as now, formed the southern shore of this gulf, and stretched
to the south-westward as a narrow peninsula in the same line as
the Thracian Chersonese. It terminated in a point near Examil,
which formed the eastern limit of the channel leading into the
interior basin.

From this point the coast-line of the Sarmatic land stretched
nearly in a straight line for about 32 miles north-east by east to
Ganos. The Sarmatic Beds now disappear under the sea-level at
(ranos, apparently cut off by the fault which bounds the deep
Marmora depression terminating at that place. They appear
again about 12 miles north-eastward at Combos, and from here the
coast-line, of steeply-dipping Oligocene rocks (fig. 2, p. 252), turned
westward, past Malgara and Keshan to Enos. From Balouk-keui,
near Feredjik, the coast, principally of voleanic and Eocene rocks,
followed the right bank of the Maritza upward nearly to Adrianople,
where another interior basin in all likelihood commenced, as
A. dArchiac indicates Sarmatic fossils, Mactra podolica, etc., at
Gheuldjik and at Nebilkeui,' in the Arda basin (3, pp. 473, 477).
From Adrianople eastward to Derkos, the northern portion of the
Sarmatic basin had a coast-line very little different from that of
the Eocene sea, since, according to Viquesnel (3, Atlas), the old
rocks to the northward are separated from the Miocene deposits by
a continuous narrow belt of Eocene strata.

In the outer basin Sarmatic fossils have been obtained as follows :—

At San Stefano I found Melanopsis costata and fragments of Unio,
in a thin seam close to the sea-level, under the /actra-limestone,
which latter extends 7 miles farther east, to Constantinople.

Along nearly the whole distance from Ganos to Examil the
Sarmatic freshwater beds, conglomerates, sands, and clays, with
lignite and petroleum, which underlie the Mactra-limestone, can be
traced as a belt from 2 to 4+ miles broad, very much dislocated by
later disturbances, but generally thinning out against the harder
Oligocene sandstones. ‘These freshwater beds, and the marine
Sarmatic which overlies them, are well developed in the Dardanelles
section, where they have been described by Calvert & Neumayr (29,

' BF. von Hochstetter (2, p. 876) misquotes Naip-kioi, near Rodosto, for
the locality of these fossils.

258 COL, 'f. ENGLISH ON THE EOCENE AND [ Aug. 1904,

p. 357), Prof. Hoernes (21, p. 7), and Prof. Toula (4, p. 8), and con-
tain fossils similar to those which I have found in the districts of
Myriophyto and Hora. These include Melanopsis aff. costata, Unio,
Anodonta, Bithynia, Limnea, Neritina, Planorbis ef. cornu, and
Melania ef. Escheri.

At Demotika and Tomletchi (between Tchampkeui and Feredjik),
Viquesnel collected several varieties of Mactra podolica (3, p. 477).
I have found Cardiuin protractum in limestone near the potteries,
about a mile north-west of Keshan, and also in thin beds of soft
limestone and clays at Ghermé Tepé, halfway along the road from
Keshan to Boz Tepé.

Harder limestone-beds, with Mactra podolica and Cardium pro-
tractum, occur about 8 miles north of Keshan, in the area between
Beyendik, Lalakeui, Mal Tepé, and Basait. At Yailah, 8 miles east-
south-east of this locality, in the direction of Malgara, the same
fossils occur. At Malgara itself, Mactra podolica is very abundant in a
soft grey limestone-bed. Near Sarkeui I have found Limnocardium
in soft shales at the southern end of the Gorgona Deré. Mactra
podolica occurs in semicrystalline limestone near Heraklitza, and
also in limestone 1 mile south-west of Dohan Aslan.

At Saraijelli, about 4+ miles south-east of Chanak, in the Dar-
danelles, Mr. Calvert has noticed an unconformity in the Miocene
formation, the lower strata, close to the Nummulitic rocks, dipping
20° south-westward, while the superposed beds are nearly horizontal.’

I do not consider that there is any adequate foundation, on the
present eyidence, for F. von Hochstetter’s determination of his
Levantine formation in this neighbourhood. The authority for
this is his statement that the uppermost strata, from Stambul to
Kutchuk Tchekmedjé, contain numerous casts and impressions of
freshwater shells (Alelanopsis, Paludina, Planorbis, and Neritina),
and therefore must be acknowledged as freshwater Levantine
deposits (2, p. 381 & map). The only fossil-locality quoted in
support of this statement is the section in the railway-cutting at
Jedikule, near Constantinople, which consists of :—

1 to 2 feet of humus ;

4 to 5 feet of yellowish shelly limestone, with numerous casts of Melanopsis

ef. ineonstans, Neritina Grateloupana (semiplicata), Planorbis cornu,
Pl. pseudammonius, Paludina (Bithynia) sp. ;

2-inch clay-parting ; 6 inches of white caleareous marl; 4 inches of clay ,

1 foot calcareous sandy bed, with countless casts of Mactra podolica ;

2 feet of white marly limestone, with conchoidal fracture ;

3 inches of clay and 1 foot calcareous sandy bed (21, pp. 31-82).

This cutting is now grass-grown, wherefore no fossils are visible ;
but Prof. Hoernes examined those obtained by F. von Hochstetter,
and came to the conclusion that the MJelanopsis-casts belonged to
M. trojana (=costata), which he had found in the Sarmatie deposits
at Erenkeui, in the Dardanelles, and that the fauna generally from
this section appears to bear a great resemblance to that of the lower
lacustrine (Erenkeu1) beds.

! Communication to the Author.

Vol. 60.] LATER FORMATIONS SURROUNDING THE DARDANELLES, 209

Prof. de Launay remarks, with respect to these Sarmatic and
Levantine deposits, that there is so much confusion between suc-
cessive paleontologists, as to make him think that they have mixed
up Pontian formations, like those of Mitylene, with the Sarmatic
horizons (6, p. 240). It must be allowed that there is some cause for
this opinion, but the recent discovery, or rather re-discovery, for they
are mentioned by Strabo (22, $ 58), of bituminous and naphtha-
bearing beds, tends to confirm the assignment of Sarmatic age to
nearly all the strata along the northern shore of the Sea of Marmora,
marked as Levantine in F. von Hochstetter’s map.

Naphtha has been found in the following localities :—-On the
north-western slope of the Tekfur Dagh, near Rodosto ; on the south-
eastern slope of the Tekfur Dagh, along the Marmora shore from
Ganos to Sarkeui; and at Balouk-keui, near Feredjik in Thrace,
where there is a thickness of about 20 feet of naphtha-sand, dipping
25° south-eastward. A bed of hard limestone-breccia, 3 feet thick,
cemented by bitumen and dipping 50° south-eastward, has lately
been discovered on the northern shore of the Sea of Marmora, near
Dohan Aslan. All the beds of naphtha and bitumen as yet traced
in this neighbourhood bear a strong resemblance to those of the
Sarmatic petroleum-district of Bustenar and Cosmina, in Rumania,
and the harder portions of the sandstones form similar globular
concretions, often 3 feet in diameter, in both localities.

The naphtha-sands along the northern shore of the Sea of Marmora
are directly overlain by the marine Sarmatic (acta-) limestones and
marls, which stretch as a coastal belt about 2 miles wide and 30 miles
long, from Kalamitza on the east, nearly to the Dardanelles, and
form a fringing border to the freshwater sands and clays. These
beds have a general slight south-easterly dip, and disappear beneath
the sea-level between Kalamitza and Myriophyto, while towards
the south-west they are overlain near Gallipoli by Upper Pliocene
deposits. They reappear in Kalo Nero Bay, forming the upper beds
which border the Dardanelles there.

In my previous paper I suggested that the naphtha-bearing beds
~ near Milos were probably Pliocene (9, p. 156); but, since I have found
Mactra-limestone at Heraklitza overlying similar beds, I see no reason
for dissociating the strata at the two localities, as, although the indi-
vidual beds are too broken up to trace, yet the series as a whole is
continuous, and I am therefore now of opinion that the naphtha-
bearing strata at Milos and Hora are Sarmatic.

At the south-eastern corner of Imbros, I found that the pro-
montory of Megalai Kephalai consists of a projection about
2 miles long and half mile wide, averaging 100 feet in height (fig. 4,
p. 260), convex to the south-east, and united to the main portion
of the island by sand-ridges 1} miles long, enclosing the large salt-
lagoon already mentioned (p. 253). The formation consists of soft
horizontal sands, clays, and marls, with a harder sandstone-bed
at the summit, and is generally light in colour. I could find no
fossils, but the appearance of the beds is identical with that of the

260 COL. I. ENGLISH ON THE EOCENE AND [| Aug. 1904,

Sarmatic strata of the Gallipoli Peninsula, which they directly face.
The width of the channel here is 10 miles, and its greatest depth is
50 fathoms.

These beds have evidently been eroded by recent sea-action over
the space now occupied by the lagoon and sand-ridges, in which
some small knolls, remnants of a clay-bed just above the sea-level,
are still visible. At their junction with the main mass of the
island, the Sarmatic strata apparently rest unconformably upon the
sloping profile of the volcanic rock, though the actual junction is
hidden by a talus of volcanic débris. The lower portion, more
especially the above-mentioned clay-bed, contains rounded andesite-
pebbles, and the whole appearance is that of a Sarmatic coast-line
near the present sea-level. The water-line, however, at the time
of the deposition of the highest Sarmatic beds, must have stood

Fig. 4.—Promontory of Megalai Kephalai, island of Imbros.
(See p. 259.)

more than 700 feet above the present shore, as the nearly-horizontal
strata on both sides of the Dardanelles are at fully that height
where they thin out against the older rocks.

Npratt’s collection of fossils from Tenedos, in the Geological Society's
Museum, includes unmistakable specimens of Mactia podolica, and
the Sarmatic waters must have covered the larger part of this island
and of the adjacent islets, as well as the western coast of the
Troad and the site of Hamaxitos, nearly as far south as Cape
Baba (17, p. 630); but, according to Prof. de Launay (6, p. 282),
no Sarmatic deposits can be traced in Lemnos or in Mitylene.

Brackish and freshwater Pontian deposits have been described as
occurring in Chios (25, p. 350), Mitylene (6, pp. 167 et seqq.), the
Troad (17, p. 630), the Dardanelles (11, p. 1546), Kassandra (20,
p. 323), the northern shore of the Sea of Marmora, and the Ergene
valley in Thrace (3, pp. 472, 480). In addition to these localities

Vol. 60.] LATER FORMATIONS SURROUNDING THE DARDANELLES, 261

there are, I believe, some small fragments remaining about a mile
south of Keshan, at Karakaya Deré, where the Oligocene sand-
stones are overlain by a thin series of soft limestones, in which I
have found Prosodacna, Dreissensia, and Neritina. At Hafus Hassan
Tchiflik, 3 miles west of Keshan, Prosodacna, Anodonta, Planorbis,
and Melanza occur in shelly sand. Near Boz Tepé, 6 miles west of
Keshan, Welanopsis Martiniana occurs ; and near Tekekeui, 3 miles
south of Keshan, I have obtained Lyrcwa Bonelli from sandy
beds overlying the Oligocene sandstones.

At Myriophyto, Bithynia and Melania were found in soft clay
taken out of a shallow well.

VII. Puriocent.

Prof. Andrussov has come to the conclusion that the Pontus
existed as a large, perhaps also deep, brackish lake, enclosed on
all sides, from the Pontian until the beginning of the Diluvial
Epoch (26, p. 73), and that the Bosphorus is the bottom of a
fluvial valley lowered beneath the sea-level (24, xxix, p. 9).

The details of several facts bearing on this question, which I have
observed, may now be given to confirm this view; and I would call
special attention to the post-Sarmatic eastward extension of
the central fold of Tertiary rocks, resulting in the upheaval
of the Dohan-Aslan and Serian-Lepé ridge This upheaval closed
the connection between the Marmora basin and the Gulf of Xeros
(Pl. XXII, fig. 2) by the formation of a dam which, though much
weathered down, is still 180 feet above the present water-level.

This upheaval, moreover, has led to the exposure of some of the
older rocks near the axis of folding. Epidote-quartz-rock, calcite
or dolomite, and chlorite, with calcareous tuffs and andesite, appear
at Dohan Aslan, while a large expanse of foliated and sheared
serpentine, with calcite, dolomite, and hornblende-schist extends,
in an east-north-easterly direction, from Bournar Oren through
Serian Tepé to Yolzdik. That this ridge is post-Sarmatic is proved
beyond question by the steep inclination away from it, on either
side, with a continuous east-north-easterly strike, of the Tertiary
sedimentaries, up to and including the Sarmatic.

The dam thus formed, confining the Marmora water from any
outlet to the westward, was the proximate cause of the cutting of
the Bosphorus, and of the drainage of the Marmora into the Black
Sea, during Pliocene times. Later on, as will be shown, it similarly
resulted in the cutting of the Dardanelles and the drainage of the
combined Black-Sea and Marmora water into the Mediterranean.

Since no traces of Tertiary deposits have been found as yet along
the Bosphorus, to my knowledge, it is useless to speculate as to
how or when the valley, which now forms the channel, first took a
connected shape in the old rocks. To all appearance it was developed
on the recession of the Sarmatic sea, as that of a river running to
the north-eastward, and confined within a narrow rocky gorge

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Vol. 60.] | EOCENE, ETC, SURROUNDING THE DARDANELLFS. 263

‘between Roumili Hissar and Kandili, where the general water-
parting between the present drainage to the Black Sea and that to
the Sea of Marmora crosses the channel (25). At Beikos Ostrea
edulis, of which a specimen is now in the British Museum (Natural
History), has been found in grey clay, about 80 feet below the
present water-level, and therefore the Devonian rock-bottom of the
lateral valley, which joins the Bosphorus at this place, must be
lower still. The Buyuk-Deré valley is also partly filled up with
brick-earth ; and if these and other lateral valleys were cleared of
their post-Tertiary accumulations, the Bosphorus channel would
take the shape of an ordinary river-valley, with numerous small
affiuents. .

The slope of the longitudinal section along the deepest part of
the channel, with the exception of a remarkable hole of 66 fathoms
abreast of Kandili, to which I shall refer later, is fairly uniform,
the depths increasing from 20 fathoms at the south-western end,
between Old Seraglio Point and Leander’s Tower, to 36 fathoms at
the north-eastern entrance, abreast of Fil Burnu, in a distance of .
14 sea-miles (see fig. 5, p. 262).

The existence, already mentioned (p. 244), of strata apparently
older than Miocene at Old Seraglio Point, and the occurrence of
soundings with rocky bottom outside this point, make it probable
that a hard rock-barrier crosses the channel here to the Devonian
rocks at Scutari. This bar gives the shallowest water in the whole
distance, 167 sea-miles, between the Mediterranean and the Black
Sea; it thus fixed a lower limit to the water-level of the Sea of
Marmora before the Dardanelles were cut, and now determines the
level at which the Black Sea would again become a closed basin.

At the time of the completion of the cutting of the
Bosphorus valley, the water in the Ponto-Caspian
lake described by Prof. Andrussov must evidently
have stood at a level nearly 200 feet lower than at
present.

I do not believe that any trustworthy evidence is available, or
likely to be obtained, to show whether the formation of the deep
depression (660 fathoms) of the Sea of Marmora preceded or followed
the cutting of the Bosphorus valley ; but the numerous earthquakes,
some of the isoseismals of which are evidently in connection with the
faults bordering this collapsed area (27, p. 151), render it probable
that the falling-in of the Marmora sea-bed is still in progress. In
either case, however, the result of the recession of the Sarmatiec
sea would be to leave one or more lakes draining north-eastward
through the Bosphorus river, and the water in these would be
freshened and lowered as the Bosphorus valley gradually attained
its present general profile at some time during the Pliocene Period.

Then the level of the Ponto-Caspian lake commenced again to
rise, so that, in correspondence with this, the Sea of Marmora
gradually extended its limits westward to Gallipoli, and the
brackish-water bed of Caspian shells, that now forms the con-
glomerate upon which the town is built, was deposited. The rise of
water gradually reached the height indicated by the beach at Hora,

’

Fig. 6.—Raised beach, 130 feet above sea-level, at Hora lighthouse,
north-western coast of the Sea of Marmora. (See pp. 263, 265.)

Vol. 60.] FOCENE, ETC. SURROUNDING THE DARDANELLES. 265

130 feet above sea-level, containing Neritina fluviatilis (=danu-
bialis), Didacna crassa, Dreissensia polymorpha, and Mytilus edulis.
This beach commemorates the last high-water mark of the Ponto-
Caspian closed basin, and probably followed a portion of the contour
of the Marmora lake at the time when the Gallipoli shell-bank
accumulated (fig. 6, p. 264).

The conglomerate-rock, upon which Gallipoli is built, consists in
great part of shells of Didacna crassa, Dreissensia Tschaude, and
Dr. polymorpha. The deposit is not, in my opinion, a raised beach,
and it is about double the height generally stated. It is spread
out over at least 2 square miles, with a fairly-uniform surface
about 80 feet above the water. At Bas-Chesmé Bay (Gallipolt), the
conglomerate is partly replaced by a local bed of sandy loam, in
which is a seam, about a foot thick, of the same Caspian shells
(Didacna crassa and Dreissensia polymorpha), evidently in or close
to their original location, as many of the shells have both valves
connected.

Prof. Andrussoy considers the Gallipoli Conglomerate to be the
equivalent of the T'schauda Beds at Kertch, containing Dreissensia
polymorpha, Dr. Tschaude, Cardium crassum, C. Cazece, and
C,. Tschaude, which he shows to be an Upper Pliocene fauna of
Caspian type, deposited in an enclosed brackish lake before the
Dardanelles were in existence (24, xxx, Table of Beds above the
Sarmatic, facing p. 4; and 26).

’ VIII. PLersrocene,

According to Prof. Philippson’s researches (14, p. 138), the
deep depressions in the A%gean district, due to tectonic collapses,
began to take shape between the Lower and the Upper Pliocene.
I propose to show that the consequent reversal of the
drainage of the Dardanelles area resulted in the
formation of a river, the watershed of which lay
south-west of Gallipoli, and that when this was worn down
by subaérial agencies to the level of the dammed-in Pontic water,
the following rapid outflow caused the formation of the Dardanelles
channel.

The first result of the tectonic changes referred to by Prof.
Philippson would be to convert the North A®gean area into a large
closed basin, bounded on the south by the chain of the Northern
Cyclades, Andros, Tinos, Mykoni, Nikaria, and Samos. The dip
of the Sarmatic strata from the Dardanelles south-westward
shows that there was considerable relative subsidence in this
direction, as the level of the Upper Sarmatic of Imbros is now
some 600 feet lower than that of the corresponding beds east
of Chanak in the Dardanelles, in a horizontal distance of about
25 miles. The Sarmatic deposits of Tenedos show a similar dip.
This settlement, on the verge of the AXgean depression, is further
indicated by an ancient river-channel, discovered by Mr. Calvert,
which has cut through the neck of land at Maitos (fig. 7, p. 264)
opposite Chanak, to within 100 feet of the present water-level.

Q.J.G.S. No. 239. T

(29¢ °d aay) *sajjaunpeng ay, buojy sprsodop auasoipy yfos fo sfygQ—S “SLT

Vol. 60. | EOCENE, ETC. SURROUNDING THE DARDANELLES. 267

' The river then apparently deserted its course for a more southerly
one, included in the present excavation of the Dardanelles below
Chanak, and conveyed the drainage both of the Dardanelles and
of the Rhodius valleys into the closed basin of the North Aégean.
The watershed dividing this new drainage from that which con-
tinued to follow the old course through the Sea of Marmora, must
have been to the south-west of Gallipoli, as no traces of the Ponto-
Caspian lake occur beyond this place, and its position was probably
determined by the subsidiary north-to-south fold of the Lower Ter-
tiary strata, which passes through Ibridji (see Pl. XXII, fig. 2).

The branch of this river-valley occupying the Upper Dar-
danelles would be of less width than the existing waterway, which
has an average breadth of about 2? miles, and therefore no traces
of it are now visible above Abydos. When its watershed was worn
down to the level (130 feet or less above the present sea) at
which the Sea of Marmora stood at that time, the valley would be
rapidly widened and deepened into the present section by the
outflow of the Ponto-Caspian.

A violent outflow of this description would account for the
scooping-out of the remarkable cavity previously mentioned as
existing in the bed of the Bosphorus opposite Kandili (p. 263), in
which, going southward, the depth increases from 33 to 66 fathoms
in half a mile (see fig. 5, p. 262). This is immediately below the
* Roumili-Hissar gorge, in which the sectional area of the present
channel is reduced to about 430,000 square feet, or three-quarters
of its normal waterway. ‘The sectional areas of the northern end
of the channel abreast of Fil Burnu, and of the southern end,
between Old Seraglio Point and Leander’s Tower, are each about
the same, that is, 560,000 square feet (28, sections).

The high cliffs of soft material, which now bound the Dardanelles
and form so remarkable a feature (fig. 8, p. 266), would readily be
shaped by the carrying away of the material protecting their bases,
without the whole section between them being necessarily occupied
by water at any one time.

Prof. Philippson concludes that the North A/gean basins were not
occupied by the Mediterranean until Quaternary times; that the
lowering of the collapsed regions is still going on; and that, in
addition, a general subsidence of the Aigean land has taken place
since the beginning of the Quaternary Period (14, pp. 135, 139,
141). It is not possible, therefore, to ascertain what the water-level
in this district was when equilibrium took place between the Ponto-
Caspian and the Mediterranean, as all traces of this event have
been since submerged. So far as the Sea of Marmora is concerned,
the profile of the south-western entrance of the Bosphorus shows
that its level did not differ materially from the present one.

There have been, as will now be shown, various considerable
oscillations of water-level since the opening of the Straits; but, so
far as I am aware, there is no evidence to show that they have not
been quietly effected, in every case, by a gradual rise or fall of
the water.

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Vol. 60.| | EOCENE, ETC. SURROUNDING THE DARDANELLES, 269

After the completion of the discharge of the Ponto-Caspian water,
and the formation of a sea-connection through the Dardanelles, the
water in the Sea of Marmora became again sufficiently salt to allow
of the entry of the existing Mediterranean fauna in early Pleistocene
times. Traces of this invasion occur at many points in the Sea of
Marmora. Vestiges of a beach-conglomerate, about 330 feet above
the present sea-level, occur, as stated in my previous paper, near
Myriophyto, on the northern shore (9, p. 159).

Quite recently, Mr. Claude Warner has traced for me the remains
of a Mediterranean shell-beach in situ at Hora, 405 feet above
the sea (fig. 9, p. 268), and about 1000 yards farther inland than the
lacustrine beach at the 130-foot level, which I had previously seen
at that place. There are numerous scattered blocks of conglomerate
at Hora, both above and below the 130-foot level, containing
Mediterranean shells, such as Mytilus edulis, Ostrea edulis, Callista
Chione, and Osilinus articulatus.

The Caspian shells (Mytilus edulis, Didacna crassa, Dreissensia poly-
morpha, and Neritina fluviatilis) were found by me in the 130-foot
beach, and in detached conglomerate-fragments. Admiral Spratt
collected Melania, Nerita, Dreissensia, and Cardium from the same
locality (1, pp. 216, 217); and the list given by A. d’Archiac
includes Congeria (Mytilus) rostriformis, Cardium ovatum, C. pro-
tractum, Paludestrina, Neritina danubialis, Mytilus spathulatus,
and Melanopsis (3, pp. 480, 481), without specifying the positions
of the beds from which they were obtained. This mixture of
fossils rendered it very difficult to draw any conclusion as to what
formations they really represented; but since Cardium, Ostrea
edulis, and Mytilus edulis have now been collected from the 400-
foot beach itself, it becomes fairly certain that the Mediterranean
marine fossils found below are derived from it, and that the
remainder are partly from the 130-foot lacustrine beach, and partly
from the Miocene strata upon which both beaches rest.

In several places along the shore-line of the Sea of Marmora,
I have found sandy and loamy clay surface-deposits, containing
scattered shells of Mediterranean species, at heights varying from
10 to 100 feet above the water.

On the top of a low coast-cliff about three-quarters of a mile west
of Gallipoli, there is a deposit of sand, hardened sufficiently in some
parts to be worked for building, in which I collected Ostrea edulis,
Osilinus turbinatus, Gibbula adriatica, and G. Biasolleti, at about
40 feet above sea-level.

About a mile farther west, on the top of a cliff 90 to 100 feet
high, formed of Sarmatic clay and marly limestone, I found a
scattered surface-deposit of Cerastoderma edule, Pullastra pullastra,
Tapes cf. Diane, Murex trunculus, M. Brandaris, Cerithium vul-
gatum, Loripes lacteus, and Petricola lithophaga. Didacna crassa
and Dreissensia polymorpha were also found, but are probably
derived from the Gallipoli Conglomerate.

Half a mile inland from Tchardak, on the Asiatic coast opposite

270 COL, T. ENGLISH ON THE EOCENE AND | Aug. 1904,

Gallipoli, I observed a surface-deposit, varying from 40 to 50 feet
above sea-level, which yielded the following section :—The lowest
bed visible is a soft yellow sand, in which I found no fossils. This is
covered by a hard concretionary shell-bed, 1 foot thick, containing
Tapes cf. Diane and Cerastoderma edule. Above this come 38 feet
of Joam, with Mediterranean marine shells scattered through
it, the quantity of shells being greatest in the upper part. The
following species were collected from the loam :—Ostrea edulis,
Tapes cf. Diane, Gibbula adriatica, Cerastoderma edule, Mytilus
edulis, Chlamys varia, Chl. opercularis, Tritia reticulata, Loripes
lacteus, Gastrana fragilis; also Dreissensia polymorpha, probably
from Gallipoli. ‘The surface-soil above these marine shell-beds is
a sandy loam, about 3 feet thick, with scattered rounded pebbles
of quartz, rhyolite, and mica-schist, fragments of pottery, and the
following land-shells :—Buliminus Lewitt, Heliv pomatia, H. cincta,
and Pomatias (Cyclostoma) elegans.

At Mavris Island, 12 miles east of Constantinople, a clay-bed
resting on the Devonian rocks, at about 10 feet abave sea-level,
yielded the following scattered shells :—Chlamys unicolor, Cardium
rusticum, and Chione gallina. On the mainland at Paulo Liman,
close to Mavris Island, I found Murev Brandaris, Cerithium vul-
gatum, Cerastoderma edule, and Cardium rusticum in a similar bed,
10 to 20 feet above sea-level.

About a mile north-east of Gallipoli, on the road to Bulair, is
a loamy clay-bed, containing a seam about 20 feet above the sea-
level, and between 1 and 2 feet thick, full of Ostrea Cyrnusii
(lamellosa). This is presumably the oyster-bed of Gallipoh,
which Prof. Andrussoy (24, xxx, Table of Beds above the Sarmatic,
facing p. 4) correlates with the Pleistocene marine shell-deposits
of the Kertch Peninsula, containing Ostrea adriatica, Mytilus latus,
Venus gallina, and Nassa reticulata; it is capped by a thickness of
about 6 feet of red clay.

From beds, none of which are more than 40 feet above the
water, at Abydos and Chanak in the Dardanelles, Calvert & Neu-
mayr collected 33 species, 28 of which are still living in the
Mediterranean, and generally widespread (29, p. 366).

Having had the advantage of discussing the question with
Mr. Calvert, I have his authority for saying that the section of the
Gallipoli Conglomerate, in Calvert & Neumayr’s paper (29, sec-
tions), has no reference to these Mediterranean shells ; also that the
Paleolithic knife, quoted by Prof. Suess (15, p. 441) as having been
found in the Gallipoli Conglomerate, was really found in the Mediter-
ranean shell-beds at Abydos, 18 miles lower down the Dardanelles.
Prof. Toula’s collection from a terrace at Yapuldak (4, pp. 14,
15), 13 miles below Gallipol, is evidently from the same horizon.
Mr. Calvert informs me that similar beds occur at Ak Bashi,
Maitos, Morto Bay, and In Tepé in the Dardanelles, and in the
plain of the Scamander. He has also found a raised beach with
Ostrea and Cardium, 80 to 90 feet above the present sea-level at
Five Pines and Usbeg, about 3 miles south-east of Abydos.

Vol. 60.| LATER FORMATIONS SURROUNDING THE DARDANELLES. 271

Prof. Hoernes describes late marine shell-beds in Samothrake,
about 650 feet above sea-level according to his section, with Cerasto-
derma edule, Ostrea lamellosa, O. cochlear, Cerithium vulgatum,

Spondylus, and Pecten (5, p. 10).

The red loamy or sandy clay, which is the latest general
deposit, and occupies a very large area in the aggregate, throughout
the district, is a feature that cannot be ignored in any discussion
of the present developments.

Burgerstein (20, p. 325) has fully described its appearance in
the Chalkidike Peninsula, and, as shown in my previous paper
(9, p. 157), it may be said to have left its traces in every direction,
up to a height of 1000 feet above the sea. It contains scratched
and facetted boulders (9, p. 158) in some of the higher localities,
and is scarcely ever free from fragments of stone. As a rule,
these are small, angular, scattered lumps of the rock which forms
the subsoil, and they correspond exactly with the fragments into
which the fissile rocks are being split up at the present time by
tree-roots, especially by those of Pinus maritima. No organic
remains have been found in it to my knowledge, except recent land-
shells, such as Pupa, Clausilia, and Cyclostoma.

This clay occurs in the most unlikely places for any fluviatile
deposit: for example, there is a well-marked patch about 8 feet
thick, and full of small angular stones derived from the underlying
rocks, which is exposed by quarrying at Roumili Hissar on the
Bosphorus. It occupies a surface-depression in the Devonian strata,
ata height of about 180 feet, on the steep rocky slope facing the
waterway.

No doubt, in many localities, this red clay has been redistributed
and locally thickened by the surface-drainage (ruissellement)
which Prof. de Lapparent (11, p. 1612) considers to be the cause of
the deposition of loess, but I think that the angular nature of the
small stones contained in it is a serious obstacle to looking in this
direction for the general origin of the formation.

In order to show the widespread nature of this deposit, I have
indicated on the key-map (Pl. XXIII) some few of the localities
where it occurs, with approximate heights (where known); but a
detailed survey would be required to give any adequate repre-
sentation of the innumerable small patches, as well as large areas,
which are met with in all parts.

This red clay bears, in many respects, a strong resemblance to the
Rubble-Drift described by Sir Joseph Prestwich, and the limiting
height agrees with his observations (30). In my opinion, the
formation in the Dardanelles district results from a
short submergence of the land to a uniform height
of about 1000 feet above the present sea-level, prob-
ably during (or shortly after) the Glacial Period. It
is obvious, however, that no rise of water could, unaided, scratch
boulders such as occur in the higher portions of the red clay.
Perhaps an explanation of this effect, and of the peculiar cha-
racteristics of the clay itself, may be found in the work of shore-

212 COL. T. ENGLISH ON THE EOCENE AND [Aug. 1904,

ice and tides, in sweeping up the surface-soil and its contents
during a submergence which allowed insuflicient time for ordinary
sedimentation.

Mr. Calvert has found boulders and clay in the Dardanelles
Valley, apparently distributed along an old beach from the foot of
Kemel to the Five Pines, also large blocks of quartz, some of them
striated, in the ancient river-gravels of the Rhodius, 50 to 60 feet
above the present sea-level. These quartz-blocks must have come
from the auriferous reef at Astyra, about 12 miles distant to the
east-south-east.

TX. Summary or OBSERVATIONS.

A list of the publications to which I have referred is annexed to
this paper; and the following is a summary of geological facts not
hitherto recorded, which I have had the opportunity of observing in
the region surrounding the Dardanelles :—

1. The Pasha-Liman group of islands and the Artaki Peninsula in
the Sea of Marmora are not volcanic, but consist of stratified
rocks which formed part of a pre-EKocene archipelago.

. The Kuru-Dagh and Tekfur-Dagh ranges are not composed

of Primary rocks (phyllit), but of Lower Tertiary lacustrine

sandstones, clays, and schists, overlying the Nummulitic Series.

They are 3000 feet thick, interstratified with volcanic rocks,

and contain Oligocene coal-seams. The Gallipoli Peninsula

and the island of Imbros are partly composed of strata of the
same age, which also occur at Tchatal Tepé, south of the Sea
of Marmora.

The Eocene and Oligocene strata are folded on a large scale.

The central fold can be traced for 200 miles through Lemnos

in a direction of 8. 60° W., according with that shown by

Prof. Philippson for the ‘ Flysch’ of Thessaly.

4. Strati Island is entirely volcanic, as is the south-east of Imbros
also.

5). Helvetian-Tortonian marine deposits occur north of the Gulf of
Xeros, and on the northern shore of the Sea of Marmora.,

6. Sarmatic strata, freshwater and marine, form the northern shore
of the Sea of Marmora from Ganos to the Dardanelles, and no
Levantine Beds are to be’ found here. Sarmatic strata also
occur near Keshan and Malgara in Thrace, at the south-eastern
corner of Imbros, and in Tenedos.

. Pontian Beds occur near Keshan.

8. There is a post-Sarmatic extension of the central fold of the
Lower Tertiary strata, from Dohan Aslan through Serian Tepé
and Mount Elias to Ganos, which has thrown up a ridge
blocking the Sarmatic connection between the Sea of Marmora
and the Gulf of Xeros.

0, The Ponto-Caspian water rose to 130 feet above the present
sea-level in Upper Pliocene times, and left a beach of brackish
lacustrine shells at Hora.

iw

z
—~
.

~

i) Pi hor Sot 2S Fs +S.
. ie Th + ain a 2
. “~. '
: > i .

“Be face p. 272.

Estimated |
approxte

pared with the present water-level. a

acknes. / ‘danelles, Marmora. Bosphorus. ‘4 pred
) aspian.
Feet. /
a LiVighiaee wees Sp A ois ape aS eo a
{Ch
Various Cae WO 5. ees? 5 - 2 Shs Se fai
Bo
Pane Shee so
4 to 10 lies >
Samq------ nie ai ahs aks ana enka a ?+ 650>
) |
12 |Hord-------- SE A he higatso aa
-Q------------ ---0--------->
-0------------ (ee aie See
Mor |
)
Pa |
tty ae ae 2 + 130 - ------- >
15 3 Se eee Q---|----->
Mait © <------ S19) eee >
ee a Se er Ret een
3 : | :
ay ere A le —120->|] ts | <—200>
80 | Mity Poe |
/
AN eke ee = Ese
500 |{ | | |
: + - + 800)- - ------------------- >
(2)200 | Hor a |
(2)100 | Kerl500 - - -|-------- ------------- -

i
el
|

Nieeaeceg f)

dlarshes -

Taste I,—Eocenr anv Laver Formations surrounDING

THE DARDANULLES.

_ SS Snnneeeerre e |

sandstones, and

Serian Depé; Gorgona Deré ;
Demotika.

Bitimated | Ticlative heights in feet, compared with the present water-level,
Series. Siaye. Nature of Beds. approwte Localities. Fossils, a =S 7 2 2
| Unekness. ) Kastern Northern) 77, |
| | Mediterranean. Cyclades.) “5°
ne Feet. | te oe ey
Surface-loam. 3 Deliardak, Tand-shells, === == =~ [Son ae ees ees)
OChalkidike ; Maritza Basin ; | H
Glacial. | Red clay. Various. Gulf of Xeros; Marmora ; Land-shells. eh tepamt em le erred WPeshase ois <M e G59 ake mons
Tecan Bosphorus ; Lemnos. ; ike? | Sa eMac Se ai se rag CoS
Mavine shell-beds { Gallipoli ; Pehardak ; Mavris Ree j |
and and terraces. } HstopLO | Island ; Dardanelles; Kertch. } Moditorvintean’eitells: | <---> +) LO to+100---.--.-5
PenisroGENa. Marine shell-bed. Samothrake. (?) Trebizond. Ostrea Cyrnusi (lamellosa). | Hl) 50 2) aay ask een a Sree
. Ostrea edulis, |
Conglomerales: | | 12 | Hora. [ Mytilus edulis, Se eeeaapne
| BB) \\| Gattista Chione. 2 Mis
| | IMEI prneres |b sreNtba oe (I) oaonl Seen me ---0-
Sicilian. | Conglomerate ; | +1166, \- he:
> marine terrace, Morea: Kos; Rhodes. Mediterranean shells. + D5AO-- -->
and shell-beds, J | + 600 to 8U0 |
Piiocene Neritinta danubialis. ? Z
s Shell-beds. 80 il apes : (?) FF }
Speirs = Gallipoli; Horn; Cape Tschauda, Dreissensia polymorpha. ee -
Lacuatrine terrace. 1 J Didacna crassa. = B
| River-channel. Maitos. s lal
{ i] os
— : —_ --— = — = = = ——| ae
| Sandy beds. 20 | Boz Tepé. Lyreea Bonelli. a a 120 ee
| Pontian. | Preshwater lime- eore eC ; e {| Vivipara meqarensis. 5 je — 120-> <—200>
| stones and clays. | Hy) wiitinllones; Wenilanellles, 1 Bithynia. Planorkis, } a 0 | 0
{ Ridge of old rocks. Dolian Aslan. paar caked pau ve ac
| Marine limestones iy San Stefano ; Heraklitza; Meenkent : i ae i +m r | all
Miocexn. | Sannin and clays. } 500 revel Hamasitos; Demotika. } TNR CTA, | | {
UE EU inant d 2) 200 ikon IBhawllenre. (agai | | Anodonta, Melanopsiscostata. pears 3 OU a a ec eee >
reshwater sands. (2) 2! ora; Wrenkenr; Peredjik. | | Rhinoceros. Naphtha. Lignite,
Portonian | gs Gaal iat,
Z Sands and sandy Fo BAN 5 . Waane Pecten aduncus. Ostrea “
{ ae limestone, } (?) 100 | Kerteh; Eregli; Myriophyto; Kasos. { | Alectryonia Virleti. crassissima | Sense arias ean ies ~ + 1466 | to 1500 - --|-------- foe a >
| Helvetian: o | ee: ey J 4 ‘ | | | |
Aquitanian.! youstrine sand- | ( Ganos; Gorgona Deré ; Corbicula semistriala. | | |
Geers Statese a Hae | Dehatal Depé ; Gueredjeé ; Anthracotheriun. |
Onigocenn. ~ Wath lave er wale 38000 Keshan ; Gallipoli Peninsula; Coal. | (2) e---e- - - Marshes -|- ----- > (?)
| ? Behe GERE i Samothrake ; Lmbros ; Chrysodium Lanzeanum. | | |
\ Lemnos. | |
| | bel! |
— ee = = : ——— -- — -— — — —. / - — ae a
| Dimestanes vara | Mount Wlias; Gorgona Deré ; | Fimbria subpectunculus, i | | |
Tnletian : Canc se ate = 2000 Vernitza ; Feredjik ; Nummulites Dufrenoyi. | |
g 8 sip = Samothrake ; Demotika ; Cladocora cf. articulata, | (2)} <--- ss ~ Archipelago -) - - = - - - >| (2)
onglomerate | pee
Wocenn. RS S: Troad. Cycloseris Perezi. } |
Conglomerates, | | |
|
|

clays.

Vol. 60.] LATER FORMATIONS SURROUNDING THE DARDANELLES. 2793

10. There have been considerable oscillations of the water-level in
the Sea of Marmora since the advance of the Mediterranean
through the Dardanelles. A beach with recent Mediterranean
shells occurs at Hora, at 405 feet above sea-level, and there
are numerous shell-beds along the shore-lines of the Dardanelles
and the Sea of Marmora, up to 100 feet.

11. Glacial or post-Glacial red clay, formed at the expense of the
surface-soil of a land-area, has been widely spread to a height
of 1000 feet, and contains scratched and striated boulders.

Dr. J.S. Flett has furnished a description, in Appendix I (p. 276),
of the more important rock-specimens; and Appendices II & II1
(pp. 277, 292) contain detailed accounts, by Mr. R. Bullen Newton
and Mr. R. Holland respectively, of the fossils which I have
collected. ‘To each of these gentlemen I desire to tender my most
sincere thanks.

Taste LI,

MEAsuRED SECTION OF STRATA AT GoRGONA DERE, NEAR SARKEUI.

Southern end of section (beds in Measured horizontal
descending order). distances in feet.
SMM RENIN ATIC CloPVS! wade cccuse-0cec- 2s dese tvwsssacecdexee nado vueaes stones 180

Green sandstones and clays with earthy coal-outcrops, brown sand-
stones with leaf-impressions, greenish-brown sandstones, dark
leafy clays, nodular coaly shales, thinly-bedded sandstones and

RI ehh eee eae Ae ana se divnn ss teh det hens che spherke 491
= tiga SSRIS oT ee Bet ip ee a Bi 516
Brownish-grey sandstones with leaf-impressions, in vertical beds... 40
ee Ae ne A aa eae akc dads doen sence Rune ag avid eee ease 156
REE AIR VCDU HELIS acne sunbiee store vdeo cenene odes se exsedeadwen Sees 18
Brown calcareous sandstones, interbedded with shales .................. 379
Thickly-bedded brownish-grey sandstones and shales ................+. 23
PILI CNISEUTNY PO? LOCWOTECAL Gigoce\er ssc scsi voce cwanseweessessecaed dotus 1380
Brown sandstones, clays, and shales, dip 80° northwar ad sicyemee 240
Brown sandstones, thin shales, and conglomer co ARR 2 ie Mare scrt et 12
Sandstones and conglomer ates, Nummulitic sandstones, grit, and

Nummulitic beds, vertical and dipping southward, ..:0..c:.enc-0srer 465
Conglomerates, brown and green sandstones with coaly leaf-

Ee NORM CERN Bric RP Eo 5s oh chin a aia yoec gbaanrantidane w2eTtSewaete ates 420
Brown and blue sandstones and shales ................csseeeecasececeeeees 255
PPrCMOPED: BY CTAVOL, GCs 2522) ciane. conssnnsnefo> + idelsde -dedaceamenees Hace 525
Brownish-blue sandstones, green sandstones with pebbles, dark-

coloured sand and prey sandstones: .......4..esccsisceessannoces sedon devas 116
Pebbly green sand, dip 45° north-westward ..........5.....scsseseseseeses 81
peeelreeereth and. Gari BARC $5.3 604.5 .0sdccpnsaedsatdade ss canny anewtahaeko 114
Dark clay, blue and brown sandstones and shales ...............000eeee 90
Green sandstones and green clays, vertical beds....................000000 78
Thin limestones, Nummulitic, dip 45° northward ..................66566 192
‘Thin sandstones and shales, vertical and inclined to south ............ 120
Nummulitic sandstones and conglomerates, vertical and inclined to

WYRE cee ener ee A MRI ot IT: Cec VOR TED Mee dge tnt boot tea seams 180
Limestones, sandstones with green and purple pebbles, and dark

UR one gees ee ee ea ed rat RL LM aniad ssehee vd gh Mahan ae 190

Sandstones, limestones, and conglomerates, Nummuliticand coralline,
gritty sandstones, shales and conglomerates, dipping northward... 234

Northern end of section.

COL. T.-ENGLISH ON THE EOCENE AND [Aug. 1904,

TasuE ITT,

MEASURED Secrion oF STRATA NEAR KesHAN, ABOVE AND BELOW THE COAL.

North-eastern end of section (beds Thickness of each
in descending order). formation in feet.
Blue shales.
Soft blue‘shales ‘in ‘thim layers” 22. sj. /asecorecpco ss es: aeumeeeaewrees \ 240
Nodular sandstones: .-k4 cot: daskeins tase nes soca et ra eena ten eee 6
Soft:blue shales in/ thin Tayerss .. cs :tn.qoecsugetconcs« saeeee eats | t& 300
Greenish sandstones, with thin layers of shale ...................0. | 40
Sandstones and shales in thin layers .....................ceceeeeeeees & 2500
Soft ‘blue shales. in:thim, layers vc.. ccreenascuens scoae ete cate | A. -132
Sandstones, with thin layers of shale.................. Por ys eer . 106
Grey, thickly-bedded, nodular sandstone ...............0.00ceeeeees \<o- ale
Soft blue shales, with thin layers of sandstone............2...0060 ‘ 2 180
Blue shalesand rhyolite »....2..cncsnqeueareser cess ence te ee ea (Ss
Thickly-bedded sandstone .............. sa Stine baleen eM en aT alae aes hers lo
COAT ac 82 wanda riag «hese gat sds war See eaes eo ay telnne oe aoe ere ne | _ 3
Thickly-bedded greenish sandstone . ....0......sessscecseeesseceeeees So 40
Blue shale, with layers of sandstone ............cscececesscecsscseneee | a4
NAYIGCSEORERS, casks ss cc evviue donw, sacercucteae meno sel Gaaee ee oe ane eee 40
Brownish-grey nodular sandstone, layers of shale ............... | 250
Thickly and thinly-bedded sandstones, layers of shale ......... 120
Thinly-bedded nodular sandstones................646 de" Gaerne teeee 4 90
Grey sandstones and: shales i.c2- wiscsafeiwseeacoconeccspeenv canes amen | 70
Grey nodular sandstones: jvcc..20scep.ccoesaeetccaen et saree omnes ee 90
Thin sandstones and shales........... OE Reem Venn) sd, Se $ S 240
Grey modtllar sandstones) 0. \iws).ccnnassancsaenaesisern nen nateR eect | 390
Thinly-bedded shales and sandstones ..............:eceseeeesoeees ) 180

Nummulitie limestone.

(9)
(10)

South-western end of section.

X. BrpiioGRAPHICcAL List.

Spratt, T. ‘On the Freshwater Deposits of the Levant’ Quart. Journ. Geol.
Soc. vol. xiv (1858) p. 212.

HocusteEttER, F. von. ‘ Die geologischen Verhaltnisse des éstlichen 'Theiles
der europaischen Tiirkei’ Jahrb. d. k.-k. Geol. Reichsanst. vol. xx (1870)
p. 365.

ViquEsneEL, A. ‘ Voyage dans la Turquie d’ Europe ’ vol. ii (1868).

Touta,F. ‘Eine geologische Reise nach Kleinasien’ Beitr. z. Palaont. u. Geol.
(Esterreich-Ungarns u. des Orients, vol. xii (1900) p. 1.

Ha@rnes, R. ‘ Geologischer Bau der Insel Samothrake’ Denkschr. d. k. Akad.
d. Wissensch. Wien, vol. xxxiii (1874) pt. ii, p. 1.

Launay, L. pr. ‘ Etudes géologiques sur la Mer Egée’ Ann. des Mines, ser. 9,
vol. xiii (1898) p. 157. :

TCHIHATCHEFF, P. pg. ‘ Asie Mineure—4°™° Partie: Géologie’ vols. i-iil
(1867-69); & ‘Paléontologie’ (A. p’Arcutac, P. FiscuEer, & KH. DE
VERNEUIL) 1866.

GARDNER, J.S., & ErvinegsHausEn, Baron C. ‘ Monograph of the British
Eocene Flora’ Paleont. Soc. vol. i (1879-82).

Eneuisu, T. ‘Coal & Petroleum-Deposits in European Turkey ’ Quart. Journ.
Geol, Soe. vol. Iviii (1902) p. 150.

SreFaNnEscu, S. ‘Etude sur les Terrains tertiaires de Roumanie’ Thése pré-
sentée a la Faculté des Sciences de Paris pour obtenir le grade de D. és Sci.
Nat. (Lille, 1897).

(11) Lapparent, A. DE. ‘Traité de Géologie’ 4th ed. vol. iii (1900).
(12) Purtrppson, A. ‘ Beitrage zur Kenntniss der griechischen Inselwelt ’ Peterm.

Mitth. Erganzungsheft 134 (vol. xxix, 1901).

“SSSATIANVOGYVG SHL .
ONIGNNOYYNS AYLNNOO SHL AO dVW-HOLSYS WWOIDOTORD

‘O2J0) ‘asoauiag

DIAWWYYS '
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any
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3NIZODINO

DINWIIWON
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odwi3 ainduv
3N3903-3nNd

IXX Td ‘X71 IOA (908 1035 ‘NYUNOP ‘LYUVAH

PL. XXII.

r

Bemrose, Collo.

Fig. 2—UPPER PLIOCENE.

PROBABLE FoLbINGs oF LoWER TERTIARY, AND CoAST-LINES OF Upper
TERTIARY FORMATIONS SURROUNDING THE DARDANELLES.

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Key-map,
giving the names of the localities
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Approximate Localities of some of

the Deposits of Red Stony EN oe
with heights in feet thus... ... *\

[For ‘ Abydus’ read ‘Abydos’; for ‘Herak .. itza’ read ‘Heraklitzn’; and for ‘ Huva’ read * Hora’.)

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Vol. 60.] LALER FORMATIONS SURROUNDING THR DARDANELLES. 2795

(13) Hinper, V. ‘ Geologische Reise in Nordgriechenland & Makedonien’ (1893 &
1894) Sitzungsberichte d. k. Akad. d. Wissensch. Wien, vol. ciii, pt. i (1894)
pp. 575, 616.

(14) Puitrppson, A. ‘La Tectonique de l Egéide’ Ann. Géograph. vol. vii (1898)
p. 112.

(15) Sugss, E. ‘La Face de la Terre’ | transl. E. de MARGERIE] vol. i (1897).

(16) Suzss, E. ‘La Face de la Terre’ | transl. E, de MARGERIE | vol. iii (1902).

(17) Drtter, J.S. ‘ Notes on the Geology of the Troad’ Quart. Journ. Geol. Soc.
vol. xxxix (1883) p. 627; & Preliminary Report. ;

(18) Anprussov, N. ‘ Ueber das Auftreten der marin-mediterranen Schichten in
der Krim’ Verhandl. d. k.-k. Geol. Reichsanst. (1884) p. 190.

(19) Buxowsx1, G. ‘ Der geologische Bau der Insel Kasos’ Sitzungsberichte d. k.
Akad. d. Wissensch. Wien, vol. xcviii, pt. i (1889) p. 653.

(20) Bureersterin, L. ‘Geologische Untersuchungen im siidwestlichen Theile der
Halbinsel Chalkidike’ Denkschr. d. k. Akad. d. Wissensch. Wien, vol. xl
(1880) p. 321.

(21) H@rnzs, R. ‘Ein Beitrag zur Kenntniss fossiler Binnenfaunen ’ Sitzungs-
berichte d. k. Akad. d. Wissensch. Wien, vol. lxxiv, pt. i (1876-77) p. 7.

(22) Straso. ‘Geography’ [trans]. Tardieu} Paris, 2nd ed. (1894). Fragments
of Lib. VII.

(23) Gonrz,— von DER. Karte der Umgegend von Constantinopel. Berlin, 1897.

(24) Anprussov, N. ‘La Mer Noire’ no. xxix; & ‘ Environs de Kertch’ no. xxx,
Guide des Excursions du VII®™® Congrés Géologique International (St.
Petersburg) 1897.

(25) TretieR, Fr. ‘Geologische Beobachtungen auf der Insel Chios’ Denkschr.
d. k. Akad. d. Wissensch. Wien, vol. xl (1880) p. 340.

(26) AnpRussov, N. ‘ Die Schichten von Cap Tschauda’ Ann. d. k.-k. Naturhist.
Hofmuseums, vol. v (1890) p. 66.

(27) Ea@tnir1s, D. ‘Le Tremblement de Terre de Constantinople’ Ann. Géograph.
vol. iv (1895) p. 151.

(28) Warton, Str Witiram. ‘Report on the Currents of the Dardanelles &

Bosphorus’ Admiralty, London, 1886.

(29) Canvert, Fr., & Neumayr, M. ‘ Die jungen Ablagerungen am Hellespont ’
Denkschr. d. k. Akad. d. Wissensch. Wien, vol. x1 (1880) p. 357.

(30) PrREstwicu, Sir Josrpu. ‘On the Evidences of a Submergence of Western
Europe & of the Mediterranean Coasts, &c.’ Phil. Trans. Roy. Soc. ser. A,
vol. clxxxiv (1893-94) p. 903.

EXPLANATION OF PLATES XXI-XXITI.
Prats XXI.

Geological sketch-map of the country surrounding the Dardanelles.

Prats XXII.

Probable foldiugs of Lower Tertiary, and coast-lines of Upper Tertiary
formations surrounding the Dardanelles.
Fig. 1. Sarmatie and Pontian.
2. Upper Pliocene.

Pruate XXIII.

Key-map of the Aigean & Marmoran area, giving the names of the
localities referred to in the text, and showing the approximate localities of
some of the deposits of red stony clay. Approximate scale: 40 miles=1 inch.

[For the Discussion, see p. 295. |

276 DR. J. 8. FLEYT ON ROCK-SPECIMENS FROM ! Aug. 1904,

APPENDIX I.

Nores on the Cottecrion of Rock-sprcimEns made by Cor. ENeLisH
in Evropean Turkny and Asis Minor. By Jonn Suivi Fert,
MzA. | DScGs:

Tne collection of specimens submitted to me by Col. English, though
not very large, included representatives of many different kinds
of rocks—sedimentary, igneous, and metamorphic. The most
numerous, however, were the recent lavas, which ranged
from rhyolites and trachytes to very basic augitites. Many of the
specimens, having been collected in the course of hurried traverses
through difficult regions, were not so fresh as might have been
desired. Yet it was possible, in nearly all cases, to form a definite
opinion regarding the nature of the rock and the group to which it
was to be assigned.

The clastic sediments and organic limestones of the Tertiary Series
require no special description, but mention may be made of the
occurrence of red, baked, and hardened, nodular shales,
which had been contact-altered apparently by lava-flows that
covered or enveloped them. None of the advanced stages of thermal
alteration were found in any of the rocks sliced. Trachytic(?),
andesitic, and basaltic tuffs were numerous, but call for
no detailed treatment.

The assemblage of crystalline, igneous, and metamorphic rocks
was on the whole very similar to that which has been described by
J.S. Diller from the adjacent district of the Troad.’ With the
exception of the nepheline-basalts, practically all the rocks
described by him were present also in Col. English’s series ; and
there were only one or two classes the occurrence of which was not
already known from Mr. Diller’s paper.

Rhyolites were certainly few, although they are reported
as abundant in the Troad; only one good specimen was collected,
at Boz Tepé, west of Keshan. It may be remarked, however, that
many of the more felspathic ‘ andesites’ were both decomposed and
much silicified, so that often it was uncertain whether originally
they might not have had the characters of rhyolites. Trachytes
were equally rare, in fact it was doubtful whether they were
represented at all.

Most of the lavas were andesitic, and hornblende-andesites
preponderated, though biotite-andesites were also common. A
pale-green pyroxene was practically always present in these latter
rocks, and in some of them tiie biotite was so intensely corroded and
so inconspicuous, that a peculiar type of pyroxene-andesite
was developed, in which the essential constituents were a pale- green
(sometimes pleochroic) augite and highly-zonal plagioclase-felspar.
Its abnormal character raised suspicions as to its true nature; and,
on further examination, it became clear that these felspathic augite-

' Quart. Journ. Geol. Soe. vol. xxxix (1883) p. 627.

Vol.60.] | THE DISTRICT SURROUNDING THE DARDANELLES. 277

andesites were merely unusual varieties of biotite-andesite.
The groundmass is commonly pilotaxitic, less frequently hyalo-
pilitic. The best example of these came from the White Cliffs
(Dardanelles). An excellent biotite-andesite was collected on
the south-eastern slope of the watershed above Panagia (Imbros) ;
it contained, in addition to large hexagonal plates of biotite, a little
much-corroded hornblende and porphyritic green augite.

Five specimens from the island of Strati were all hornblende-
andesites (containing a little dark-brown biotite), and were
exceptionally fresh and good examples of this class of rocks.
Typical hypersthene-andesites, much decomposed, occur at
Korou.

Olivine-basalts were found on the Kuru Dagh and near
Keshan: from the latter locality some peculiar rocks were obtained.
One of these resembled an augitite; another consisted of olivine,
brownish augite, biotite, plagioclase, and orthoclase-felspar, with
an abundant clear glassy base.

In the Serian-Tepé district, examples of serpentine, amphi-
bolite, epidote-amphibolite, and serpentine-schist occur.
The serpentines include weathered dunites and harzburgites.

AppEnpDIx II.

Norrs on the post-Terttary and Tertiary Fossits obtained by
Cor. Enexisu from the Disrricr surrounding the DARDANELLES,
By Ricuarp Butien Newron, Esy., F.G.S.

[Pate XXIV.]

ConsIDERABLE interest may be attached to the fossils collected by
Col. English in a number of localities surrounding the Dardanelles,
since many of the specimens rank as fresh records for this part of
South-Eastern Europe. One of the most important results accruing
from an examination of the coilection has been the fixing of the
age of the coal-deposits at Masatly, which can now be
referred to the Stampian or Middle division of the
Oligocene System, on account of the discovery of Corbicula
semistriata in those beds at that locality, in association with
Anthracotherium-remains,
The specimens are scheduled under the following formations :—

Post-PLIOcENE.
Priocens (Sicilian).
f Pontian.
Miocene / Sarmatian.
| Vindobonian (Helvetian--Tortonian).
{ Aquitanian.
| Stampian.
Eocene... Lutetian.

OLIGOCENE

The whole of the collection has been generously presented to the
British Museum (Natural History) by Col. English.

278 ' MR. R. B, NEWTON ON FOSSILS FROM [Aug. 1904,

Post-Pliocene.

Marine mollusca found in the region of the Dardanelles have
been identified with existing Mediterranean species. Hence, the
deposits containing them may be recognized as of post-Pliocene
age, and probably of contemporaneous origin with those found in
Cyprus (as known to us through the researches of Prof. Gaudry),
and in the Hellespont by Calvert & Neumayr.

(A) List of marine shells from the coast-cliffs west of Gallipoli,
40 to 100 feet above sea-level.

GASTROPODA. LAMELLIBRANCIITA,
Murex Brandaris, Linneus. Ostrea edulis, Linneeus.
Murex trunculus, Linneeus. Cerastoderma edule (Linnzeus),
Cerithium vulgatum, Bruguiére. Pullastra pullastra.
Gibbula adriatica (Philippi). Petricola lithophaga (Retzius).
Gibbula ef. Biasoletti (Philippi). Loripes lacteus (Poli).
Osilinus turbinatus (Born). Tapes Calverti, sp. nov. (= Tapes ef.

Lhane, Locard).

(B) A marine shell from Gallipoli Ovassi, about one mile north-east
of Gallipoli, in a loamy clay-bed 20 feet above the sea.

Ostrea Cyrnusii, Payraudeau.!

(C) List of marine shells from the other side of the Dardanelles
opposite Gallipoli, about 1 mile inland from Tchardak. The
beds containing this fauna are of a sandy character, and nearly
50 feet above sea-level. The exact section measures about
10 feet in thickness, and is capped by a loamy soil full of
recent terrestrial shells.

GASTROPODA. LAMELLIBRANCHTA,
Tritia reticulata (Linneus). Ostrea edulis, Linneeus.
Gibbula adriatica (Philippi). Chlamys opercularis (Linneeus).

Chlamys varia (Linneeus).

Cerastoderma edule (Linnseus),

Mytilus edulis, Linneeus.

Gastrana fragilis (Linnseus).

Loripes lacteus (Poli),

Tapes Calverti, sp. nov. (= Tapes
cf. Diane, Locard),

The specimens of Tapes cf. Diane, which occur both at Tchardak
and Gallipoli, agree with Calvert & Neumayr’s shells from the
(Quaternary deposits of the Hellespont which are similarly identified.”

1 Ostrea Cyrnusii was originally*described by Payraudeau (‘Catalogue des
Annélides & des Mollusques de I'Ile de Corse’ 1826, p. 79, pl. iii, figs. 1 & 2)
as living off Corsica. lt is narrowly-elongate in form, and furnished with an
extensive ligamental area. The more modern figure, published by Reeve in
his ‘Conchologia Iconica’ vol. xviii (1878) pl. xvii, fig. 37, of the lower valve
of this shell agrees in every way with the specimen collected by Col. English.
It may be mentioned that this species is generally united to O. lamellosa, as
one of its synonyms.

* Denkschr. d. k. Akad. d. Wissensch. Wien, yol. xl (1880) p. 366 & pl. ii,
figs. 7-8.

Vol. 60.} THE DISTRICT SURROUNDING THE DARDANELLES. 279

‘This form of Tapes is not only extinct, but it differs sufficiently in-
proportions and contour from Locard’s original 7, Dianw, which
was obtained from the Miocene of Corsica,’ as to necessitate another
name: that of Tapes Culverts is therefore proposed for it.

(D) List of shells from Paulo Liman, occurring in a surface-clay
about 20 feet above the sea.

GASTROPODA. LAMELLIBRANCHIA,
Cerithium vulgatum, Linneus. Cerastoderma edule (Linnzus).
Murex Brandaris, Bruguiere. Cardium rusticum( =tuherculatum)

Linnzus.

(E) List of shells from a disintegrated beach of clay and stones
about 10 feet above sea-level, occurring at Mavris Island (Sea
of Marmora).

LAMELLIBRANCHIA.
Chione gallina (Linneus).
Cardium rusticum (=tuberculatum) Linneus.
Chlamys unicolor (Lamarck).
This deposit and the preceding (D) are of a later post-Pliocene
age than those of Gallipoli and Tchardak.

(F) List of terrestrial shells found in a loamy soil capping the
marine beds at Tchardak. They were associated with fragments
of pottery, and are of very recent age.

GASTROPODA.

Helix pomatia, Linnzus.

Helix cineta, var., Miller.
Buliminus Lewitt (Philippi).
Pomatias elegans (Draparnaud).

(G) Marine shells found in a conglomerate at Hora, about 400 feet
above sea-level and 1000 yards inland from the lighthouse at
this locality.

GASTROPODA, LAMELLIBRANCHIA.

Osilinus articulatus (Born). Ostrea edulis, Linnzeus.
Mytilus edulis, Linnxus.
Callista Chione ( Linnzeus),

(H) A sandy conglomerate forming a raised beach, containing recent
Mediterranean shells, from near Kayak Deré.

LAMELLIBRANCHIA.

Ostrea edulis, Linnzeus.
Anomia ephippium, Linnzus.
Chlamys opercularis (Linnzeus).
Amussium cristatum (Bronn).

In connection with the determinations of the recent mollusca

\ ‘Description de la Faune des Terrains tertiaires moyens de la Corse’ 1877,
p- 190 & pl. vil, figs. 1-3.

280 MR. R. B, NEWTON ON FOSSILS FROM {[Aug. 1904,

in the foregoing lists, the writer desires gratefully to acknowledge
the assistance given to him by his colleague at the British Museum,
Mr. Edgar Smith, 1.8.0.

Phocene (Sicilian).

The Pliocene shells of this collection, chiefly obtained from the
Gallipoli Conglomerate, are of lacustrine habit and bear the Caspian
facies. Admiral Spratt’ was one of the earliest geologists to call
attention to the lacustrine or freshwater deposits skirting the
margins of the Grecian Archipelago, the Sea of Marmora, and the
Black Sea, all of which he thought were indications of the former
existence of an ‘Oriental Lake’ extending over those areas to the
Sea of Azov. Two of the more frequent shells found in the Marmora
beds resembled a Mytilus and a Cardiwm, and were long recognized
as marine forms; but, on examining the fauna of Lakes Kattabug
and Yalpuk, Spratt ascertained that the so-called Cardium (= Didacna)
was living there in fresh water, and differed from the marine genus
in having two syphons. He had also recognized the same shell in
the Kertch deposits and in the Gallipoli Conglomerate, where it

was associated with the Mytilus-like shell, or Dreissensia of modern
conchologists ; hence he concluded that these freshwater mollusca
péloneeas to his great ‘ Oriental Lake-Period.’

In the British Museum (Natural History) are some excellent
examples of this Cardiwm-like shell, now determined as Didacna
crassa, &@ species originally described by Eichwald from the Caspian
Sea. These specimens, forming part of Admiral Spratt’s collection,
were obtained from sandy marls underlying red, earthy drift-deposits
at Babel, on the eastern coast of Yalpuk Lake (Bessarabia), and
were presented by Col. F. T. N. Spratt-Bowring, R.E., in 1892.

Prof. Andrussoy,? who has studied the fauna of the Gallipoli
Conglomerate, regards it as of Upper Pliocene age, and synchronizes
it with the T'schauda Beds of the Kertch Peninsula, since both
deposits contain Didacna crassa, Kichwald* (Pl. XXIV, figs. 1 & 2),
Dreissensia polymorpha, Pallas (Pl. XXIV, fig. 3), and Dr. T'schaude,
Andrussov (Pl. XXIV, fig. 4).

Besides these shells from the Gallipoli Conglomerate, the present
collection contains examples of a nearly-identical conglomerate from
Hora, 130 feet above sea-level, exhibiting lacustrine conditions.
Although Dreissensia Tschaude is not identifiable in this rock, the
other two lamellibranchs are recognized, besides Neritina fluviatilis

1 Quart. Journ. Geol. Svc. vol. xiii (1857) pp. 72-83; ibid. vol. xiv (1858)
pp. 208-19 ; & dbid. vol. xvi (1860) pp. 281-92.

2 See ‘Environs de Kertch’ Guide des Excursions du VII’™* Congrés Géol.
Intern. (St. Petersburg, 1897) no. xxx.

8 Didacna crassa is recorded as occurring still farther eastward, in the
district of the Caucasus between Cape Bailov and Baku, by Prof. N. I. Lebedev,
in Dr. Gustav Radde’s ‘ Die Sammlungen des Kaukasischen Museums’ vol. iii
(1901) p. 160 & pl. iv, figs. 713 a0.

Vol. 60.] HE DISTRICT SURROUNDING THE DARDANELLES. 281

and fragments of Mytilus edulis. The appearance of the last-
named among lacustrine species need not be wondered at, as it has
been recorded as living in the Caspian and Black Seas by S. P.
Woodward‘ and other authorities.

(A) List of lacustrine shells from the Gallipoli Conglomerate.

LAMELLIBRANCHIA.

Dreissensia polymorpha (Pallas).
Dreissensia Tschaude, Andrussov.
Didacna crassa, Eichwald.

(B) List of lacustrine shells from the Hora Conglomerate (130 feet).
GASTROPODA. ' LAMELLIBRANCHIA.

Neritina fluviatilis (Linnzus). Dreissensia polymorpha (Pallas).
| Didacna crassa, Eichwald.
Mytilus edulis, Linnzeus.

Miocene (Pontian).

The collection contains a few lacustrine mollusca, which prove
the presence of Pontian deposits in the region of the Dardanelles.
Prof. S. Stefanescu > appears to be the principal authority on the
Pontian and the succeeding Sarmatian groups of rocks, especially
im connection with Rumania, his latest researches being summarized
in a ‘ Thesis’ containing valuable faunistic lists, comparative tables,
and a comprehensive bibliography.

By this it is evident that Dreissensia rimestiensis and Prosodacna
ef. stenopleura (both collected by Col. English) are characteristic
Pontian shells; while an equally-typical shell of this stage of
the uppermost Miocene is the gastropod, Lyrcwa Bonelli, which
Dr. Brusina’ has recorded from Hungary and Servia.

Species of Pontian age :—

( Lyrcea Bonelli, Brusina. (Pl. XXIV, figs. 5 & 6.)
Dreissensia rimestiensis, Fontannes. (Pl. XXIV, figs. 7 & 8.)
} Prosodacna cf. stenopleura, 8. Stefanescu. (Pl. XXIV, figs.

9 & 10.)
Locality.—Found in beds occurring above the Nummulitic Limestone,
| at a brook north of Teke-keui.

| Neritina. Dreissensia.
; Prosodacna.
| Locality.—Keshan (Kara Kaya Deré).
Planorbis. Anodonta.
Melania. Prosodacna.
| Locality.—Near Keshan (Hafus Hassan Tehiflik).

1 «A Manual of the Mollusca’ 3rd ed. (1875) p. 69. ©

2 These présentée a la Faculté des Sciences de Paris: ‘Etude sur les Terrains
tertiaires de Rowmanie’ (Lille, 1897) pp. 124-26. See also Fontannes, ‘ Faune
malacologique des Terrains Néogénes de Roumanie’ Arch. Mus. Hist. Nat.
Lyon, vol. iv (1887) pp. 322-61 & pls. xxvi-xxvii.

3 *Jeonogr., Moll. Foss. Tert. Hungarix, &c.’ 1902, p. 7 & pl. v, figs. 29-32.

Q. Ji G. S. No. 239. U

282 MR. R. B. NEWTON ON FOSSILS FROM [ Aug. 1904,

Miocene (marine Sarmatian).

Marine Sarmatian shells have been obtained from the limestones,
etc., of San Stefano, Heraklitza, Dohan Aslan (near Keshan), Mal-
gara, etc., the most important being Mactra podolica and Cardium
protractum. M, podolica is a typical Sarmatian species, while the
Cardium is found in the Crimea in beds of similar age.

Macrra poporica, Kichwald. (Pl. XXIV, figs. 16-18.)
Mactra podolica, Eichwald, ‘ Naturhistorische Skizze von Lithauen, &c.’ 1830,

>)
Race ee & M. biangulata, Abich, ‘Geologie d. Kaukasus’ Mem. Acad.
Imp. Sci. St. Petersb. ser. 6, vol. ix (1859) pp. 531, 582, figs. 1-4 (p. 514) &
pl. viii, figs. 4a & 46.
Mactra podolica, Hoernes, ‘ Foss. Moll. Tert.-Beck. Wien’ Abhandl. d. k.-k. Geol.
Reichsanst. vol. iv (1859) pt. i, p. 62 & pl. vii, figs. 1-8.

Good specimens of this shell occur in a reddish siliceo-caleareous
rock at Heraklitza, showing external and internal features in every
way agreeing with the figures published by A. d’Archiac in
Viquesnel’s ‘ Voyage dans la Turquie d’Europe’ (1868) pl. xxiv,
figs. 1 & 2.

Further examples of the species are observed in another reddish
rock from Charkeui, in the same neighbourhood, and obscure e¢asts
are present on a white limestone from San Stefano, near Con-
stantinople. Beside these, matrix-casts, of various sizes and of
somewhat rounder form, occur abundantly in a reddish rock accom-
panied by an indeterminable Cardiwm, at Yailah. Similar natural
casts are frequent ina grey formation of marly character at Malgara,
while a very different rock from this also comes from near Malgara,
which is full of a small, globulose, thick-tested shell, probably
representing the younger stage of the species(P1. XXIV, figs. 17 &18).
Abich has figured some very rounded forms of Mactra podolica (under
the names of JM. deltowes of Lamarck and I. biangulata of Pusch),
from the Middle Tertiary deposits of Russian Armenia, which,
although of larger size than the present specimens, may bear a
relationship to them. ‘These globulose specimens from Malgara
have highly-crystalline tests, which prevent any development of
internal characters, sothat the dentition is not exposed. A moderate-
sized example has the following dimensions :—Height =12 milli-
metres; length =13; maximum depth with closed valves =11.

One of the samples of this rock shows indistinct traces of a
Cardium.

Horizon.—Miocene (Sarmatian).

Localities.—Heraklitza ; Charkeui ; San Stefano; Yailah ; near
Malgara ; and Dohan Aslan.

Carpium prorractum, Eichwald. (Pl. XXIV, fig. 19.)

Cardium beso Eichwald, ‘ Zoologia Specialis,’ vol. 1 (1829) p. 283, pl. v, fig. 9
W. H. Baily, Quart. Journ. Geol. Soc. vol. xiv (1858) p. 144; A. tae
in Viquesnel’s ‘ Voyage dans la Turquie d'Europe’ vol. ii (1868) p. 480;
P. Fischer, ‘Faune Tertiaire Moyenne’ in Tchihatcheff’s ‘ Asie Mineure:
Paléontologie’ (1866) p. 356 & pl. vii, fig. 3.

This species is represented by a few well-preserved casts having

Vol. 60.] THE DISTRICT SURROUNDING THE DARDANELLES. 283

a variability of contour, some being more transverse than others.
It is of frequent occurrence in the marly rocks of Ghermé Tepé,
Yailah, etc. Originally it was described from Podolia, but since then
the species has been identified by Baily from the Crimea (specimens in
the British Museum), by A. d’Archiac from Turkey, and by Fischer
from the neighbourhood of the Bosphorus (between Yerlukeui and
the fort of Kilia).

Horizon.—Miocene (Sarmatian).

Localities.—Yailah; north-west of Keshan (the Potteries) ;
Ghermé Tepé, near Keshan ; Yailah-Ghonué; and from a brook east
of Teke-keui.

Miocene (lacustrine Sarmatian).

Sarmatian freshwater deposits occur in the neighbourhood of
Kerassia, and have yielded the following fossils :—

Planorbis cf. cornu, Brongniart.

Limnea.

Melania cf. Escheri, Merian.

Bithynia, in association with a large flattened Anodonta (indet.).

Neritina, accompanied by the casts of a small trigonal Unio
(= Unio cf. Spratti, Calvert & Neumayr).

Anodonta, a large, somewhat crushed form, in a grey marly
matrix, which appears to be intermediate between the
A. cygnea of modern European rivers and the A. helles-
pontica from the Sarmatian deposits of the Dardanelles.

The other species of Sarmatian age are as follows :—

if Planorbis cornu, Brongniart.
Melanopsis incerta, Férussac. (Pl. XXIV, figs. 12 & 13.)
Melanopsis buccinoidea, var., Férussac.
4 Melania ct. Escheri, Merian. (Pl. XXIV, fig. 11.)
Unio Delesserti, Bourguignat. (Pl. XXIV, fig. 14.)
| Unio sp.

( Locality.—In a drab-coloured marly clay, Potamina Deré.

Planorbis cornu, Brongniart.

Unio cf. Spratti, Calvert & Neumayr.
Limnocardium.

Corbicula.

Cypris.

Locality.—In drab-coloured marly clays, from near Arabli.

Halitherium ? (a lumbar vertebra, determined by Dr. C. W.
Andrews).

Diplomystus marmorensis, sp. nov., A. S. Woodward (see
p- 284).

Unio cf. Delesserti (impression of valve).

Limnocardium associated with Cypris (ostracoda).

A _-, ———H—

\ Locality.—Gorgona Deré (southern end) near Sarkeui (Sea of Marmora).

The fauna here tabulated contains certain species which have been
already noticed by Calvert & Neumayr,’ Prof. R. Hoernes,’ etc.,

1 P. Fischer in Tchihatcheff’s ‘Asie Mineure: Paléontologie’ (1866) p. 549
& pl. vi, fig. 2.

2 Denkschr. d. k. Akad. d. Wissensch. Wien, vol. xl (1880) p. 374.

3 Sitzungsberichte d. k. Akad. d. Wissensch. Wien, vol. lxxiv (1876-77) pt. i,

pp. 7-34.
v2

284 MR. R. B. NEWTON ON FOSSILS FROM [ Aug. 1904,

as occurring in the Sarmatian deposits of the Dardanelles or of
its immediate neighbourhood, Among these may be mentioned :—
Planorbis cornu, Melania cf. Escheri, Melanopsis buccinoidea, var...
M. incerta, Unio Delesserti, U. cf. Spratti, ete.

A freshwater deposit occurs beneath the marine Mactra-limestone
at San Stefano, from which Col. English has obtained some excellent
specimens of Melanopsis costata (P1. XXIV, fig. 15), associated with
fragments of an Unio. This alternation of marine and non-marine
conditions in the Sarmatian Series has already been alluded to by
Prof. Hoernes ’ in connection with the same locality. Prof. Gaudry *
has recorded the occurrence of Melanopsis costata in the lacustrine
Miocene of Attica, which would suggest the contemporary deposition
of these two sets of beds.

Pisces.

DIPLoMYSTUS MARMORENSIS, sp. nov. (Pl. XXIV, fig. 28.)

The type- and only-known specimen of this new species is
preserved for the most part in impression, but exhibits many of its
essential features. Its total length to the extremity of the caudal fin
must have been originally about 58 millimetres, while its maximum
depth in the abdominal region would be 12mm. The length of
the head with the opercular apparatus is about 15 mm. The jaws
are not observable; and the large orbit is the only distinct feature
in the head. The slender, constricted vertebral centra are shown
in longitudinal section, and seem to have been pierced by a
persistent remnant of the notochord. There are about twenty-four
vertebre in the abdominal region, and fourteen in the caudal region.
The ribs are moderately stout, and clearly meet the large ridge-
scutes at the ventral border. ‘here are also indications of numerous.
inter-muscular bones. The small pectoral fins are exhibited; and
one of the pelvic fin-supports shows that the pelvic fins were inserted.
immediately behind a point opposite the origin of the dorsal fin.
The dorsal fin is comparatively small, but comprises at least twelve
rays: the distance between its termination and the caudal fin is
slightly less than that between its origin and the occiput. The
anal fin arises slightly behind the posterior end of the dorsal, and
is not more extensive than the latter fin: its rays probably number
12. The ventral ridge-scutes, about 20 in the series, are uniform
in size, and each is produced behind into a slender point. The
dorsal ridge-scutes immediately behind the occiput are only seen in
imperfect impressions, which appear to indicate that each was
longer than broad. There are no traces of ordinary scales.

Among known species, Diplomystus marmorensis agrees most
closely with D. humilis, from the Eocene Green-River Shales of
Wyoming (U.S.A.), and with D. vectensis, from the Lower Oligocene
Osborne Beds of the isle of Wight. It is essentially identical with

* Verhandl. d. k.-k. Geol. Reichsanst. 1875, p. 174.

> *Animaux fossils & Géologie de l’Attique’ 1862, p. 406 & pl. lxii, figs. 7-15.

Vol. 60.] THE DISTRICT SURROUNDING THE DARDANELLES. 285

both these species in the number of vertebre ; and it also agrees
with D. humilis in the characters of the ridge-scutes and the
extent of its median fins. In these species, however, the head is
smaller, and the dorsal fin farther forward than in the new form ;
while D. vectensis is also easily distinguished by the greater extent
of its anal fin, which comprises sixteen or seventeen rays.

[ A. Sarra Woopwarb. |

Formation.— Miocene (lacustrine Sarmatian). The matrix
is a light-coloured calcareous sandstone.

Locality.—Found on the surface of the ground at the southern
end of Gorgona Deré, near Sarkeui (Sea of Marmora.)

Miocene (Vindobonian = Helvetian-Tortonian).

The oldest marine Miocene shells that have been determined
belong to the Helvetian-Tortonian Period, or Vindobonian (of
Depérét), and were obtained from Eregli and Fakirma in the Gulf of
Xeros ; from near Myriophyto Deré, about 700 feet above sea-level ;
and from Tzenguerli Deré.

Those from Eregli include :—_Alectryonia Virlett, Deshayes ; Ostrea
lamellosa, Brocchi; Pecten aduncus, Eichwald; Anadara diluvii,
Lamarck, which is also found at Fakirma.

From Myriophyto Deré, 700 feet above sea-level :—Ostrea cras-
sissima.

From Tzenguerli Deré :—Ostrea gingensts (Schlotheim).

These are species characteristic of the Vindobonian (= Helvetian-
Tertonian) rocks of countries skirting or near the Mediterranean,
such as Egypt and Northern Africa, Greece, Persia, etc. The
specimens of Pecten aduncus, Eichwald, are well interpreted by
Fuchs’s figures of examples from Egypt.’

Oligocene (Aquitanian & Stampian).

‘Some light-brown to drab-coloured sandstones have been obtained
from north-west of Beyendi-keui and south-east of Lala-keui,
showing dicotyledonous leaf-impressions, one of which appears to
resemble Myrica lignitum, as identified in the British Museum
(Natural History), a form common to the Parschlug Beds of Styria,
and of Aquitanian age. It is, therefore, probable that these plant-
remains belong to the same horizon.

The presence of Stampian Beds (or Tongrian of older authors) at
Masatly and north-west of Keshan, ete., is much more certain,
however, as the characteristic shell Corbicula semistriata (= Cyrena
subarata, Bronn) has been determined, associated with Melanopsis
ef. fusiformis and Anthracotherium-teeth (of small size, and possibly
related to A. cf. minus, a form characteristic of the Hempstead or
Stampian Beds of the Isle of Wight). The Anthracotheriwm-remains

1 «Beitrage zur Kenntniss der Miocanfauna gyptens, Xe.’ in ‘ Palzonto-
graphica’ vol. xxx (1883) p. 54 & pl. xix, figs. 1-5.

286 MR..R. B. NEWTON ON FOSSILS FROM: [Aug. 1904,

are found actually in the coal-beds at Masatly accompanied by
Corbicula semistriata, thus fixing the age of the coal as Middle
Oligocene, or the Stampian stage of that Period.’

A single imperfect specimen of what is considered to be Corbicula
semistriata was obtained by Mr. Claude Warner, when boring for
petroleum 3 miles inland from Hora, at a depth of rather more
than 1000 feet from the surface.

MamMALIA.

ANTHRACOTHERIUM cf. minus, Cuvier. (Pl. XXIV, fig. 20.)

Anthracotherium minus, Cuvier, ‘Recherches sur les Ossemens Fossiles’ 2nd ed.
vol. iii (1822) p. 403, & vol. v (1824) pt. ii, p. 528.

Anthracotherium ct. minus, Lydekker, ‘Catal. Foss. Mammalia Brit. Mus.’ pt. ii
(1885) p. 242.

Remains of Anthracotherium associated with Corbicula semi-
striata have been found embedded in a sample of coal from Masatly.
These consist of anterior molars and premolars belonging to both
sides of a mandible, which are of much smaller size than those
characterizing either A. magnum or A. alsaticum, being probably
related to A. cf. minus occurring in the Hempstead Beds of the Isle
of Wight, and provisionally identified as such by Mr. R. Lydekker
from material in the British Museum (Natural History). It may
be stated that Dr. C. W. Andrews agrees with this determination,
and, like myself, experiences some difficulty in analysing any
differences that may exist between the teeth from Hempstead and
those from the Turkish locality.

Horizon.—Oligocene (Stampian).

Locality.—Masatly.

Motiusca—GAsTROPODA.

Metanoprsis cf. FustForMis, J. Sowerby.

Melanopsis fusiformis, J. Sowerby, ‘ Mineral Gonchology’ vol. iv (1822) p. 35 &
pl. cecxxxii, figs. 1-7; J. Morris, in Forbes’s ‘Isle of Wight’ Mem. Geol.
Surv. (1856) p. 156 & pl. vi, fig. 7.

The specimens referred to this form of .Welanopsis agree remark-
ably well with Morris’s figures published in Forbes’s ‘ Isle of Wight.”
The narrower and more elongate aperture appears to separate the

1 Anthracotherium is essentially a genus of the Oligocene Period, not having
been found, so far as can be ascertained, either below the Sannoisian or above
the Aquitanian stages of that group of rocks. It occurs, ameng other European
localities, in lignites of Lower Tongrian age near Gran in Hungary, as recorded
by Hébert & Munier-Chalmas, associated with Corbicula semistriata, C. R.
Acad. Sci. Paris, vol. lxxxv (1877) p. 184 ; and Prof. Heernes reports it, without
however the sbell, in the coal-formation of Transylvania, Verhandl. d. k.-k.
Geol. Reichsanst. 1878, p. 146; while the present discovery at Masatly forms
the most south-easterly point in Europe for this genus.

As the Hempstead Beds of England are correlated by Prof. Renevier,
Prof. A. de Lapparent, and others with the Middle or Stampian (=Rupelian)
stage of the Oligocene, it is considered that the palxontological evidence is
in favour of the Masatly beds belonging to the same horizon.

Vol. 60.] THE DISTRICT SURROUNDING THE DARDANELLES. 287

species from those figured by A. d’Archiac in Viquesnel’s work * as
M. incerta, Férussac, var. Melanopsis fusiformis is characteristic
of the Headon Beds of England.

Locality.—Keshan Colliery, associated with Corbula and in-
determinable plant-remains.

Horizon.—Oligocene (Stampian) greenish marls,

MotiuscAa—LaMELLIBRANCHIA.
CoRBICULA SEMISTRIATA, Deshayes. (Pl. XXIV, figs. 21-23.)

Cytherea (?) convexa, Brongniart, in Cuvier’s ‘Recherches sur les Ossemens
Fossiles’ 2nd ed. vol. 11 (1822) pt. ii, pp. 282, 284, 458, 462, 612 & pl. vii,
tigs. 7 a—7 b (insufficiently defined for adoption).

Cyrena semistriata, Deshayes, ‘ Encycl. Méthod.’ vol. ii (1830) pt. i, p. 52.

Cyrena subarata, Bronn, ‘ Lethea Geognostica’ 2nd ed. vol. 11 (1838) p. 958 &
pl. xxxviii, fig. 2.

Cyrena semistriata, J. Morris, in Edw. Forbes’s ‘ Tert. Fluv. Marine Formations
of the Isle of Wight’ Mem. Geol. Surv. (1856) p. 148 & pl. iti, fig. 2.

The specimens representing this species exhibit the variations of
contour referred to by John Morris in 1856. Some of the valves
are more equilateral, others being more obliquely produced on the
posterior side; the dentition is solid, strong, and prominent, and
the concentric sulcate structure is rather more pronounced on the
anterior than on the posterior side of the shell.

This is a very characteristic species of the Oligocene Period, having
been collected in England and in many Continental countries, such
as France, Germany, Hungary, Galicia, etc. At Fontainebleau,
nearly 40 miles south-east of Paris, it is abundantly found in beds
which Prof. A. de Lapparent and others recognize as Middle
Oligocene, or the so-called Stampian part of that system. Vacek *
records its occurrence in the Menilit-Schiefer (=Stampian of A. de
Lapparent) near Alsd-Vereczke, on the confines of Galicia, in
association with Meletta sardinites, and considers that the beds
should be synchronized with the Lower Oligocene of Schilag, in
Transylvania, as described by Dr. K. Hofmann.’ Hébert &
Munier-Chalmas* recognized the shell in the Hungarian lignites
of Gran, and Dr. E. Fournier’ records it from the Central Caucasus.
Lastly, it is well represented in the Hempstead Beds of England.
As a fossil from the region of the Dardanelles, it is now known for
the first time.

Horizon.—Oligocene (Stampian).

Localities.—Masatly ; Harmanly; north-west of Keshan; and
3 miles inland from Hora.

CoRBULA sp.
A small trigonal form of Corbula makes up very largely the green
marly rock found at Keshan. The specimens are difficult to diagnose,

‘Voyage dans la Turquie d’Europe’ vol. ii (1868) pl. xxiv 4, figs. 4 & 5.
Jahrb. d. k.-k. geol. Reichsanst. vol. xxxi (1881) pp. 200-202.
® Verhandl, d. k.-k. Geol. Reichsanst. 1881, p. 16.
C. R. Acad. Sci. Paris, vol. lxxxv (1877) p. 184.

° These présentée 4 la Faculté des Sciences de Paris: ‘ Deser. Géol. Caucase
Central’ (Marseille, 1896) pp. 184, 186.

yb »

cs

288 MR. R. B. NEWION ON FOSSILS FROM [ Aug. 1904,

as they are embedded in the matrix, and there are no clean isolated
examples for examination. A large anterior tooth can be seen in
one of the right valves, followed by a triangular cardinal cavity ; and
the external sculpture is certainly of an unequal concentric character.
A. d’Archiac described C. Saulcyz* from Mal Tepé, which is larger
than the present species, but in contour shows a resemblance that
would suggest the possibility of the new specimens being young
examples of the same.

Locality.—Keshan.

Horizon.—Oligocene (Stampian), associated with Melanopsis
cf. fustformis and indeterminable plant-remains.

PLANT-REMAINS.

Plant-remains, in the shape of dicotyledonous leaf-impressions,
have been collected in a brook lying north-west of Beyendi-keui and
south-east of Lala-keui. The matrix is a sandstone varying in
colour from light-brown to drab, but the specimens themselves are
not determinable, and consequently they are of little use for hori-
zonal purposes. One of them resembles Myrica lignitum, Heer, as
represented by specimens in the British Museum (Natural History),
from Parschlug in Styria: consequently, it is probable that these
plant-deposits belong to the Aquitanian stage of the Oligocene.

Horizon.—Oligocene (Aquitanian ?).

Indeterminable plant-remains are found associated with Me-
lanopsis cf. fusiformis and Corbula sp. in the green marly rock.
They are merely impressions, one having a stem-like character.
These specimens bear no affinity with the sandstone plant-impressions
containing the supposed Myrica lignitum.

Locality.—Keshan.

Horizon.—Oligocene (Stampian ?).

Eocene (Lutetian).

The following fossils, belonging to the Middle or Lutetian
stage of the Eocene Period, have been determined as occurring at
Tzenguerli Deré, Gorgona Deré, Vernitza, and Teke-keut.

Mou.vsca. ! FORAMINIFERA.
Spondylus subspinosus, D’ Archiac. | Nummulites Dufrenoyi, D’ Archiac.
Fimbria subpectunculus (D’Orbigny). Numimulites cf. distans, Deshayes.
Locality.—Tzenguerli Deré. | Nummutites (probably) variolaria
| (Lamarck),
ACTINOZOA. | Nummulites (probably) Heberti,
; : : D’Archiac.
Cladocora cf. articulata, Abich. | Discocyclina (probably) papyracea
Locality.—Gorgona Deré. | (Boubée).
Trochocyathus sp. | Discocyclina (probably) dispansa
Cycloseris cf. Perezi, Haime. (J. de C. Sowerby).

Locality.—Vernitza. _ Locality.—Vernitza.

* See Viquesnel’s ‘ Voyage dans la Turquie d’Europe’ vol. ii (1868) p. 478 &
pl. xxv 0, fig. 13.

Vol. 60.] THE DISTRICT SURROUND ING THE DARDANELLES. 289

ForaMINIFERA (continued), ForaMInIFera (continued).
Nummulites (probably) like those from _Globigerina.

Vernitza. Rotaline forms.
Discocyclina, : Locality.—Mount Elias.
ao” © oo Rock-specimen containing Vummu-

: 3 ee | lites

Alveolina (near to) oblonga, D’Orbigny. ;
= eee ) a — | Locality.—Teke-keui.
Biloculina. For fuller information respecting
Polymorphina. _ the Foraminifera, see Mr. R. Hol-
Miliolina. land’s Report, Appendix ITI, p. 292.

Motivusca— LAMELLIBRANCHIA.
SponpyLvs susspinosus, D’Archiac. (Pl. XXIV, figs. 24 & 25.)

Spondylus subspinosus, D’ Archiac, ‘ Descr. des Foss. du Groupe Nummulitique,
&c.’ Mém. Soc. Géol. France, ser. 2, vol. iii (1850) pt. ii, p. 437 & pl. mili, fig. 1.
Represented by a single valve showing a regular convexity.
The surface is ornamented with rounded ribs of considerable
strength, separated by deep and prominent grooves, the sides of
which, as well as the ribs, are covered with extremely-fine transverse
striations. The specimen is imperfect on the right side, so that the
exact number of ribs cannot be ascertained, but about nineteen
can be counted ; in all probability, therefore, the original number
was about 23, that for the type-specimen being from 21 to 23.
No auricles are preserved, and the ribs have been subjected to
some eroding influence, as their summits are frequently smooth and
not striated. Occasionally, short and thick spines are observable
on the ribs, especially near the sides of the valve. The dimen-
sions exceed those of the type, as the following comparison will
illustrate :—

Col. English’s specimen. Type.

SONG 5 0b ss2550 60 millimetres. 45 mm.

Wiep tae erie. ee cen-ee 52 mm. 39 mm.

Except in size, therefore, the specimen from Turkey appears to
correspond with the type described and figured by A. d’Archiac from
the Nummulitic rocks of Biarritz.

Dr. E. Fournier reports its occurrence in the Middle Eocene
deposits of the Central Caucasus.’

Horizon.—Middle Eocene (Lutetian): matrix containing num-
mulites.

Locality.—Tzenguerli Deré.

Frsris suBPEcTUNCULUS, d’Orbigny.

Corbis pectunculus, Lamarck, ‘ Hist. Nat. Anim. sans Vert.’ vol. v (1818) p. 537;
Deshayes, ‘ Descr. Cog. Foss. des Environs de Paris’ vol. i (1824-35) p. 87 &
pl. xiii, figs. 3-6.

Corbis subpectunculus, D’Orbigny, ‘ Prodrome Paléont. Strat. Univ.’ vol. ii (1850)
p. 387.

Fimbria subpectunculus, Deshayes, ‘ Descr. Anim. sans Vert.’ vol. 1 (1860) p. 607.

Corbis subpectunculus, D’Archiac, in Viquesnel’s ‘ Voyage dans la Turquie
d’ Europe’ vol. ii (1868) p. 459.

Represented by a fragmentary right valve, showing the

These présentée a la Faculté des Sciences de Paris: ‘ Descr. Géol. Caucase
Central’ (Marseille, 1896) p. 182.

290 MR. R. B. NEWTON ON FOSSILS FROM [Aug. 1904, —

characteristic sculpture of this robust shell. The species was
originally described from the Middle Kocene of France, and it was
recognized by A. d’Archiac as occurring in the Eocene deposits
of Sarikaia (Rumelia) and in the Crimea.’

Horizon.—Middle Hocene (Lutetian).

Locality.—Tzenguerli Deré.

Actinozoa (CoraLs).
Crapocora cf. AarTicuLATA, Abich.

Cladocora articulata, Abich, ‘Ueber das Steinsalz & seine geologische Stellung
im russischen Armenien’ Mem. Acad. Imp, Sci. St. Petersb. ser. 6, vol. ix
(1859) p. 96 & pl. vin, figs. 1 a-1 6.

Specimens showing cylindrical tubes measuring 5 millimetres in
diameter, which are externally covered with granulose longitudinal
cost ; in these and their septal characters, so far-as can be ascer-
tained, they appear to be related to the Cl. ariwculata, as described
by Abich, from the Nummulitic rocks of Russian Armenia.

H orizon.—Middle Kocene (Lutetian).

Locality.—Gorgona Deré, near Sarkeui.

TROCHOCYATHUS sp.

Small turbinate coral resembling the genus T'rochocyathus.
Diameter =15 millimetres; height =30 mm.

Horizon.—Middle Eocene (Lutetian).

Locality.—Vernitza.

CyctosEris cf. PErrzi, Haime. (Pl. XXIV, figs. 26 & 27.)

Cyclolites Borsonis, Michelin, ‘ Iconographie Zoophytologiqué’ 1840-47, p. 266 &
pl. 1xi, fig. 2 (won Michelin, pl. viii, tig. 4).

Cycloseris Perezi, Haime, in D’Archiac, ‘ Histoire des Progrés de la Géologie’
vol. 111 (1850) p. 229.

Cycloseris Perezi, Bellardi, ‘Catal. raisonné des Foss. nummulitiques du Comté de
Nice’ Mém. Soc. Géol. France, ser. 2, vol. iv (1852) pt. ii, p. 288.

Cycloseris Peresi, Haime, in D’Archiac & Haime’s ‘ Description des Animaux

foss. du Groupe Nummulitique de ? Inde’ vol. i (1853) p. 193.

There are three specimens belonging to the genus Cycloseris
which are related to C. Perez, a Lutetian species recognized from
France and India (Scind). The calyx is subcircular, with a
diameter ranging from 30 to 40 millimetres, the height of the coral
being about 10 mm. The specimens are nummiform above but
turbinate below, and the septa are probably more tortuous than
straight (as originally described), although they are equally thin and
numerous, being well exposed marginally, finely dentated, and
minutely granulated on the lateral surfaces. The slightly-turbinate
basal region is covered with a thin concentric epitheca, through
which the costations are seen; while its central area forms a
rounded horizontal section of about 9 millimetres in diameter, ex-
hibiting a series of thickened septa, the chief of which extend to a
papilla-like columella.

Horizon.—Middle Hocene (Lutetian).

Locality.—Vernitza.

' «Histoire des Progrés de la Géologie’ vol. iii (1850) p. 259.

.— 2 —_—
=
= ee ro
7 hides le ee
vee wt One
2 —
——s

b To

\

Quart .Journ.Geol. Soc Vol. LX,P1.XXIV.

F.H. Michael del.et Lith, Le MinternBros.imp.
TERTIARY FOSSILS FROM DISTRICT SURROUNDING THE DARDANELLES.

( Nat. stxe, ecccopt where otherwise marked

Vol. 60.] HE DISTRICT SURROUNDING THE DARDANELLES, 291

EXPLANATION OF PLATE XXIV.

[Ali the figures are drawn of the natural size, except where otherwise stated.
The specimens are preserved in the British Museum (Natural History). |
Didaena crassa, Kichwald. (See p. 280.)
Pliocene (Sicilian): Baschesmé Bay, Gallipoli.
Fig. 1. External view of right valve.
2. View showing umbonal summit and dentition of the same valve.
[L. 13661.|
Dreissensia polymorpha, Pallas. (See p. 280.)
Pliocene (Sicilian) : Gallipoli.
3. External aspect of a left valve—the specimen is attached to a con-
glomeratic matrix filling the interior of a valve of Didacna crassa.
[L. 13661. ]
Dreissensia Tschaude, Andrussoy. (See p. 280.)
Pliocene (Sicilian) : Gallipoli.
4, Outer view ofa right valve. [L. 138662.]

Lyrcea Bonelli (Sismonda), Brusina. (See p. 281.)
Miocene (Pontian): from above the Numimulitic Limestone
at a brook north of Teke-keui.
5. Front aspect, showing aperture.
6. Dorsal view of the same shell.
Dreissensia rimestiensis, Fontannes. (See p. 281.)
Miocene (Pontian): from above the Nummulitic Limestone
at a brook north of Teke-keui.

7. External view of a right valve.
8. Inner view of a left valve, belonging to another specimen. X2.

Prosodacna cf. stenopleura, 8. Stefanescu. (See p. 281.)
Miocene (Pontian): from above the Nummulitic Limestone
at a brook north of Teke-keui.

9. Interior of a right valve.
10. External view of the same specimen.
Melania cf. Escheri, Merian. (See p. 283.)
Miocene (Sarmatian): Potamina Deré.
11. Fragmentary specimen, exhibiting sculpture-characters closely
resembling this species.
Melanopsis incerta, Férussac. (See p. 283.)
Miocene (Sarmatian) : Potamina Deré.
12. Apertural view.
13. Dorsal view of the same specimen.
Unio Delesserti, Bourguiguat. (See p. 283.)
Miocene (Sarmatian): Potamina Deré.
14. External view of a right valve.

This determination is according to D’Archiac’s interpretation of
Bourguignat’s species from Palestine: see Viquesnel’s ‘Voyage [dans
la Turquie d'Europe’ vol. ii (1868) p. 479 & Atlas, pl. xxiv, fig. 1a.

Melanopsis costata, Olivier. (See p. 284.)
Miocene (Sarmatian): found beneath the Mactra-
Limestone at San Stefano.

15, Front view of a specimen showing the characteristic sculpture of this
species.

292 MR. R. HOLLAND ON NUMMULITES FROM [| Aug. 19¢4,

Mactra podolica, Eichwald. (See p. 282.)
Miocene (Sarmatian): Heraklitza, and near Malgara.

Hig. 1

_~

5. Limestone-cast of a right valve, showing pallial and muscular scar-
impressions (Heraklitza).

17. | Two views of an example of the small globose form which may re-

18. { present the young condition of this species (near Malgara). x13.

Cardium protractum, Hichwald. (See pp. 282-83.)
Miocene (Sarmatian): Ghermé Tepe.
19. Natural cast of right valve.

Anthracotherium cf. minus, Cuvier. (See p. 286.)
Oligocene (Stampian): Masatly.

20. Coronal aspect of what is probably a 2nd molar tooth belonging to
the left ramus of a mandible. [M. 8246.]

Corbicula semistriata, Deshayes. (See p. 287.)
Oligocene (Stampian): Masatly.
21. External aspect of the right valve of a specimen with closed valves.
22. Dorsal view of the same, showing the summits, ligament-area, &e.
23. Interior of a right valve of another specimen, exhibiting dentition,
lateral sockets, ete.

Spondylus subspinosus, D’Archiac. (See p. 289.)
Eocene (Lutetian): Tzenguerli Deré.
(The matrix of this specimen contains nummulites.)

24. External aspect of valve, showing the strong longitudinal ribs with
oceasional short thick spines.

25, Magnification of sculpture-striations observed on the ribs of the left
lateral region, which has been less subjected to eroding influences
than other parts of the specimen.

Cycloseris cf. Perezi, Haime. (See p. 290.)
Eocene (Lutetian): Vernitza.
26. Upper surface of calyx, showing the crowded and dentated character
of the septa.
27. Basal view of another specimen, exhibiting the fine costations through
the thin epitheca; the dentated margin; and the central area
with the thickened septa,

Diplomystus marmorensis, sp. noy. (See p. 284.)
Miocene (Sarmatian): Gorgona Deré (southern end).
28. Left lateral aspect.

Apprenpix III.

Notes on NumMutites in the TurKisu Rocks described by
Cox, ExetisH. By Ricuarp Hortanp, Esq.

[Prare XXV.]

There appear to be at least three species of nummulites (giving
six forms) in the rocks from Vernitza. These are :—

1. (Pl. XXYV, figs. 1-3.) A large nummulite having a width of
from 45 to 50 millimetres, and a thickness of from 5 to 10 mm.
It is microspheric, and there are eleven to twelve turns of the spiral

Vol. 60.] THE DISTRICT SURROUNDING THE DARDANELLES. 293

inaradiusof3mm. The filets cloisonnaires are sinuo-striate
Height 24 im,
Wadthin 5h ay
septal angle is about 45°. The spire is irregular after the first
few turns, and the line of the spiral duplicates and coalesces
occasionally.

This nummulite is identified as Nummulites Dufrenoyi, D’Archiac,
form B.’ De la Harpe refers V. Dufrenoyi to the N. complanata
of Lamarck. It undoubtedly belongs tothe complanata-group ; but
it is quite sufficiently distinct, as D’Archiac has shown, and the
true JV. complanata nowhere occurs in these rock-specimens. More-
over, the ‘companion’-form of the species differs from NN. Tchiha-
tcheffi, D’Archiac, which is the ‘companion’ of JV. complanata.

2.(P1.XXV,fig.4.) A moderate-sized nummulite varying in width
from 8 to 10 millimetres, and having a thickness of about 5 mm.
Megalospheric, with six turns of the spiral in a radius of 3 mm.
Filets cloisonnaires sinuo-striate and rather coarse. Spire
Height 4 3
Width 5’ 3°
Surface non-tuberculate, but the ‘pillars’ are visible as white
specks on a varnished surface. Septal angle = about 50°. This
nummulite occurs in great abundance in the main Nummulitic
rock at Vernitza. It agrees fairly in dimensions with WV. Tchiha-
tcheffi, D’Archiac, but differs considerably in the general appearance
of its horizontal section. It is identified as V. Dufrenoyi, D’Archiac,
form A.

3. (Pl. XXV, fig. 5.) A microspheric nummulite, measuring
about 15 mm. in width, and rather thin. Filets cloisonnaires
sinuo-radiate. Delicate in its characters. The dimensions are not
given, because very few specimens have been secured sufficiently well
preserved for accurate measurement, and no specimen from which
the thickness could be properly measured. On the other hand, a
varnished specimen has furnished a fairly-good photograph of the
spire, except the first few turns. This nummulite is provisionally
identified as a variety of NV. distans, Deshayes, form B.° :

4, (Pl. XXYV, fig. 6.) A megalospheric nummulite, rather smaller
than No. 2, varying in width from 5 to 8 mm. and in thickness from 3
to4mm. The spire is regular at first, and gives seven or eight turns in
a radius of 3 mm.; it then frequently becomes more or less irregular.
The filets cloisonnaires are sinuo-striate, and more delicate
Height 2
Widen — 1 "apes
angle = about Although in external appearance this num-
mulite and No. 2 are somewhat similar, the spiral characters are
strikingly different. This No. 4 is provisionally identified as a
variety of NV. distans, Deshayes, form A. A goodly number of

and delicate. The chamber-ratio is irregular:

fairly regular. The chamber-ratio is rather irregular:

than in No. 2. The chamber-ratio is regular:

io

1 D’Archiac & Haime, ‘ Description des Animaux fossiles du Groupe Nummu-
litique de l’Inde’ 1853, p. 89 & pl. i, figs. 4a—4e.

2 Deshayes, ‘ Descr. Foss. rec. en Crimée, &c.’ Mém. Soe. Géol. France, vol. iii
(1838) p. 68 & pl. v, figs. 20-22 ; D’Archiac & Haime, ‘ Descr. Anim. foss. Groupe
Nummulitique de Inde’ 1853, p. 91 & pl. ii, figs. La-c, 2a, 8a, 4a, 54, & 5b.

294 MR. R. HOLLAND ON NUMMULITES FROM [Aug. 1904, _

specimens have been examined, but it does not occur in profusion
in the rock.

5 & 6. Two very small nummulites, about 3 or 4 mm. in width.
These occur in the rocks in great profusion, but they are very
difficult to deal with, because of their minute size and crystalline
condition. It has not been found possible hitherto to obtain good
split specimens. Several have been ground down and then varnished,
but they have not furnished results such as to justify the identifica-
tion of the species. It is thought that there are two forms—one
microspheric and one megalospheric; and roughly they resemble
N. variolaria, Sowerby,’ and WN. Heberti, D’Archiac.?

All these nummulites are highly crystalline. Nos. 2 & 4 split
readily under the usual treatment, though the process spoils nearly
50 per cent. of the specimens operated upon. When they are split
the crystalline condition entirely masks the internal structure, but
this is fairly well brought out by the use of a varnish of Canada
balsam dissolved in benzol. Nos. 1 & 3 split with very great
difficulty, and, in fact, to obtain the spiral characters of No. 3 it has
been necessary to grind a specimen down to the median plane and
then use varnish. In spite of the intractable nature of the speci-
mens, Mr. H. W. Burrows, F.G.8., has kindly attempted to get some
micro-photographs ; and he has succeeded (by the use of the acetylene-
light) in securing from opaque varnished specimens results which are
highly satisfactory in the circumstances.

Associated with the nummulites in the rocks are numerous
Orbitoides. It has not yet been found possible to separate out any
good specimens, but a transparent section of the ‘ black’ rock shows
a few of the chambers of the median plane in one of the Orbitoides.
These chambers are clearly rectangular, and the Orbitoides are
Discocyclines. It is probable that the species Orbitoides ( Disco-
cyclina) papyracea and O. (D.) dispansa both occur.

Other Nummulitic rocks from the neighbourhood of Mount Elias
have also been examined. Some of them contain nummulites and
Orbitoides in outward appearance not unlike those from Vernitza,
but it has not been found practicable to isolate specimens good
enough and numerous enough to examine them properly for
purposes of identification.

Three transparent slides cut from the rocks of Mount Elias have
been examined. These contain, in addition to Nummulites and
Orbitoides, Orbitolites (probably O. complanata), Alveolina (near
A, oblonga), numerous Teuvtilarve, Biloculina, Polymorphina, Miho-
lava, and several Globigerine and Rotaline forms.

1 Thomas Brown, ‘Illustrations of the Fossil Conchology of Great Britain ’
1849, p. 37 & pl. xxvi, figs. 8-5; and D’Archiac & Haime, ‘ Description des
Animaux fossiles du Groupe Nummulitique de l’Inde’ 1853, p. 146 & pl. ix,
figs. 13a-13q.

* D’Archiac & Haime, op. cit. p. 147 & pl. ix, figs. 14a-14g, 15, & 1lda.

Quart. JourRN. GEOL. Soc. VoL. LX, PL. XXV.

Bentrose, Collo.

DARDANELLES.

Hl. W. B., Photogr.
NUMMULITES FROM THE COUNTRY SURROUNDING THE

Paid
Rik ™

Vol. 60. ]

THE DISTRICT SURROUNDING THE DARDANELLES. 295

‘It is deduced from other paleontological evidence that these beds
are of Lutetian age. There appears to be nothing in the forami-
niferal evidence to conflict with this view.

Fig. 1.

to

He = OO

EXPLANATION OF PLATE XXV.

Nummulites Dufrenoyi, D’Archiac, form B. External view, showing the

pW.
<a,
ac.
N.
oN.

delicate sinuo-striate filets cloisonnaires. Natural size.
Dufrenoyi, D’Archiac, form B. Transverse section in matrix.
Natural size.

Dufrenoyi, D’Archiac, form B. Segment of central whorls on the
median plane of a split section. x 10.

Dufrenoyi, D’Archiac, form A. Central whorls on the median plane
of asplit section. x 8.

distans, var., Deshayes, form B. Central whorls on the median
plane of a ground section—the first few turns wanting. x 10.
distans, var., Deshayes, form A. Central whorls on the median
plane of a split section. X 10.

Discussion.

The Presrpent said he considered that the paper was an excellent
illustration of the value of geology in throwing light upon the
origin of the present superficial features of the earth.

Dr. C. W. Anprews thought that remains of Anthracotherium
were not of very great value for the determination of horizons, as
that genus had a considerable range, and closely-allied forms occurred
in the Upper Eocene and Miocene of Egypt. Nevertheless, its occur-
rence in the Dardanelles area was of extreme interest, and further
finds might well throw considerable light on the distribution of the
early Ungulates.

Mr. R. B. Newron pointed out that there could be no question as
to the Oligocene age of the Anthracotherium-remains obtained from
the coal-deposits at Masatly, since they were found associated with
Corbicula semistriata, a very characteristic shell of that period.

Mr. A. P. Youne said that it seemed likely that some of the
igneous rocks exhibited would, on analysis, yield interesting
results. The green pyroxene observed in one of the slides might
prove to be wholly or in part a soda-iron silicate, such as frequently
crystallized out from magmas in which the alumina-constituent
was deficient in respect of alkalies.

The AvurHor thanked the Fellows present for the reception
accorded to his paper.

296 PROF. G, DE LORENZO ON THE HIsTORY OF [ Aug. 1904,

19. The History of Votcanic Action in the PuireRman FIexps.
By Prof. GrusErrE pe Lorenzo, of the Royal University of
Naples... (Communicated by Sir Arcurpatp Gurxin, Sc.D.,
Sec.R.8., V.P.G.S. Read April 13th, 1904.)

[Puates XXVI-XXVIITI: Maps & Sgcrions.]

ConTENTs.
Page
1. Joitrodwebion :o.5.55nqsces<s <coe< dee see see Peet eee 296
LI: ‘Orie. of the Bay of Naples 3. 20. ae 297
III. The Eruptions in the Phlegrwan Fields .................. 300
TV > ‘Gonchusious(s. esci2lscckssssmecenas eee peewee e oe beldee 314

I. InrRopUCTION,

Tue scene that discloses itself to the observer who enters the Bay
of Naples by the so-called Bocca Grande, presents three parts,
each characterized by distinct features. On the right, masses of
calcareous pink and white rock rise up into the Island of Capri
from the foam-flecked waters of the Mediterranean, and stretch
through Sorrento and Amalfi to the cloud-capped Apennine. On the
left, a vast succession of undulating ridges of tawny-coloured tuff
begins, first at the Island of Ischia, and then, extending through
Vivara and Procida, spreads out into the gentle declivities upon
which Naples is built. In the central background looms grand
and solemn the smoking peak of Vesuvius.

Just as these three components of the landscape are diverse in
aspect, so too are they diverse in geological origin and constitution.
The island of Capri and the peninsula of Sorrento are made up of a
gigantic pile of dolomitic and calcareous deposits of Upper Triassic
(Hauptdolomit) and of Cretaceous (Urgonian-Turonian) age.
Upon these rest in places a few insignificant patches of Eocene-
Miocene Flysch. Vesuvius is a typical volcano of concentric
accumulation (vuleano a recinto), almost entirely built up of
leucotephritic, fragmental, and lava-form materials. Between
Naples and Ischia les a vast and complex assemblage of extinct
craters, which have erupted much fragmental material but little
lava, generally of a trachy-andesitic character, though excep-
tionally the crater of Vivara has disgorged a basaltic magma.”

This region, more especially that portion of it lying between
Naples, Cuma, and Miseno, received from the early Greek colonists
the name of the Phlegrean Fields. These men, as they beheld
the titanic warfare between the subterranean volcanic forces and
the calmer agencies of the atmosphere, pictured it as a great battle

1 Translated by the Assistant-Secretary.
> G. de Lorenzo & C. Riva ‘Il Cratere di Vivara nelle Isole Flegree’ Atti
R. Accad. Sci. Napoli, ser. 2, vol. x (1901) no. 8.

Vol. 60. ] VOLCANIC ACTION IN THE PHLEGRZAN FIELDS, 297

between the giants and the gods, terminating in the ultimate victory
of the latter.

In the month of March 1903, 1 made some memorable excur-
sions in this region with Sir Archibald Geikie, who urged me to
give a summary of the results of my researches into its volcanic
history, which might be submitted to the Geological Society of
London. In now complying with this request, I am not unmindful
of the many errors and omissions to which the student of so
complicated an eruptive area is liable, an area wherein every
new excursion propounds fresh problems and suggests unsuspected
mysteries.

In order to trace this volcanic history with most satisfaction, it
is desirable, first of all, to understand the geological structure of
the great basin of the Bay of Naples, in which the eruptions have
taken place.

Il. Origin oF THE Bay oF NAPLES.

The same rocks as those which form the backbone of the Apennines
constitute also the fundamental skeleton of the Neapolitan area:
that is, Upper Triassic dolomites, Cretaceous dolomites and lime-
stones, Flysch (Eocene-Miocene) sandstones and marls. These
strata, the combined thickness of which is some 3300 feet, have
been dislocated and fissured by the post-Eocene orogenic uplift of
the Apennines.’ While this upheaval contorted the softer deposits
of the Flysch into innumerable narrow folds, or left patches of
them imprisoned within and pinched into the fissures opened up in
the underlying Mesozoic formations, the rigidity of these last-
named rocks formed a sufficient obstacle to their plication into
tightly-packed folds. Consequently they were slightly curved into
broad domes and large basins, which in their turn were fractured
by dynamic agencies, and the dismembered masses slipped along
the fracture-planes, step-faults, etc. being thus originated.

One of these fractured basins is precisely the great calcareous
hollow which, sweeping round from the Island of Capri and the
Peninsula of Sorrento past the hills of Nola, Caserta, and Capua,
and projecting again into the sea at Massico, embraces, as within
one colossal amphitheatre, the entire Campania Felice. In Capri
and Sorrento the strata dip north-westward, at Caserta westward,
and at the Monte Massico south-westward. Thus they form a
synclinal depression, the major axis of which, trending north-west
and south-east, is some 434 miles long. The entire rim of this
great basin is broken by huge longitudinal fractures, striking
sensibly parallel with the Apennines (from north-west to south-
east); and by transverse fractures perpendicular to the first-
mentioned, and therefore trending south-west and north-east.

But the present configuration of the Apennine country is no
longer such as it was broadly outlined by the post-Eocene uplift.

1 For this and the subsequent observations, see G. de Lorenzo ‘ Studii di
Geologia nell’ Appennino meridionale’ Atti R. Accad. Sci. Napoli, ser. 2,
vol. viii (1897) no. 7.

Q.J.G.8. No. 239. x

298 PROF. G, DE LORENZO ON THE HISTORY OF ([ Aug. 1904,

That uplift, towards the end of the Miocene Period, raised our
mountains to a level probably higher than the present one, and
thus exposed them to long-continued denudation. In this way
there gradually disappeared from the summits of the great broken
calcareous massifs every trace of the softer Eocene and Miocene
sediments, which nevertheless remained sheltered in the wide and
deep synclines, and were mantled over by later deposits.

After the great uplift, this region was subjected in Pliocene
times to another depression, and the sea flowed in again over the
mountains. Thus itis that we find the great Pleistocene terraces
carved out on Aspromonte up to an altitude of 4265 feet above the
present sea-level, and in the remainder of the Apennines up to
3280 feet and more.

But when the Pliocene age came to an end, a fresh uplift
marked the beginning of the Pleistocene, an uplift which is still in
progress, and has been and is accompanied by seismic phenomena
and by the active vulcanicity of the Southern Apennines. To
such vicissitudes also the fundamental structure of the Bay of
Naples has been subjected.

Confining ourselves to that portion of the area which les nearest
the volcanic formations, that is, to the Peninsula of Sorrento and
the Island of Capri, we find there (as before stated) dolomites and
limestones of Triassic and Cretaceous age. The Tertiary deposits
have been all but completely swept away by the long-continued
post-Eocene denudation, a mere patch of Eocene-Miocene Flysch
now surviving on the highlands between Amalfi and Castellamare
di Stabia; while another, rather larger patch, lies amid the low-
lands of Sorrento and Massa, in the hollows formed by depression.
Not a remnant is now left among these hills of the Upper Pliocene
or the marine Pleistocene; but the blocks thrown up from the old
crater of Vesuvius * and the artesian wells dug in Naples (at the

toyal Palace and on Piazza Vittoria) prove that such deposits,

containing shells nearly all of which are identical with species
now living in the Bay, occur at the very bottom of the basin,
beneath the deposits of volcanic material, at little more than
650 feet below the present level of the sea. We may, then, conclude
that the volcanic eruptions of the Neapolitan area
began somewhere between the end of the Pliocene and
the beginning of the Pleistocene Period, upon the
bottom of a great synclinal basin, resembling those to
be seen elsewhere in the Apennines, but in part
drowned by the sea.

The southern rim of this basin now projects above the waters,
in the shape of the Island of Capri and the Peninsula of Sorrento.
But, just as the various elevations and depressions of both island
and peninsula are primarily due to the transverse and longitudinal
fractures, which have broken up the calcareous massif into so

1H. J. Johnston-Lavis ‘The Ejected Blocks of Monte Somma’ Trans.
Edin. Geol. Soe. vol. vi (1893) p. 314.

Vol. 60.) VOLCANIC ACTION IN THE PHLEGR#ZAN FIELDS. 299

‘many fault-blocks, subsequently sculptured by atmospheric agencies:
so do the Island of Capri and the Peninsula of Sorrento themselves
in reality form part of a single great calcareous mass limited by the
submarine contour of 3280 feet, and measuring at least 7870 feet
from top to bottom, of which thickness only about 4590 feet now
emerges from the waves (see Pl. XX VI).

This great mass is followed on the north-west by a second, which
rises from the 3280-foot submarine contour to about 650 feet
below sea-level (see Pl. XXVI & Pl. XXVII, section) ; and this
is divided from the first by an embayment, which in all probability
corresponds to a valley of transverse fracture, analogous to all the
others known elsewhere in the Apennines. The character of the
contours, more precipitous on the south and more gentle on the
north, suggests the inference that in this submarine massif, just as
in the Peninsula of Sorrento, the strata dip from south-east to north-
west, and are cut off by a great fracture on the south-east. . In this
second mass the marine Tertiary and Quaternary sediments have
been naturally better preserved, because they were more protected
from erosive agencies. The blocks ejected from Monte Somma
have furnished abundant evidence in favour of this conclusion.

To sum up then, the bottom of the Bay of Naples, originally
moulded by the orogenic post-Kocene folding and by the post-
Pliocene uplift, is chiefly composed of two great masses of lime-
stone and dolomite, intensely fractured and dislocated, the con-
stituent strata of which dip en masse towards the foci of eruption.
This synclinal dip of the strata towards the volcanic centre, obsery-
able also in the Monte Vulture,’ and at other localities, is doubt-
less favourable to eruptive phenomena, perhaps for the reason that
it carries deeper down the dislocated material, which then becomes
subject to powerful thermal agencies with the consequent produc-
tion of an igneous magma. This hypothesis is, to some extent,
confirmed by the fact that in the neighbouring Gulf of Salerno,
where dislocations are both more considerable and more numerous
than in the Bay of Naples, but in which the arrangement of the
strata is anticlinal, there is not the faintest trace of eruptive
phenomena. Whatever may be the origin of the deep-seated
magma, certain it is that the Pleistocene submarine eruptions
emerged above the sedimentary masses, dislocated and folded into
a basin, in the Bay of Naples. First came those of Ischia and of
other crateriform vents, which built up the whole Campanian
plain with sanidine-bearing materials, which are also found
heaped up at Sorrento and Capri, and along the range of the
Southern Apennines. These discharges were followed by a less
widespread phase of vulcanicity, represented by the trachy-andesitic
rocks of the Phlegrean Fields and the leucotephritic material of
Vesuvius. While, however, at the Vesuvian vent the eruptions
have discharged fragmental and lavaform materials from one single

1 G. de Lorenzo ‘Studio geologico del Monte Vulture’ Atti R. Accad. Sci.
Napoli, ser. 2, vol. x (1901) no. 1.
be

300 PROF, G. DE LORENZO ON THE HISTORY oF =[ Aug. 1904,

persistent chimney, in the Phlegrwan Fields, on the other hand, a
long series of outpourings and explosions took place from many
different funnels and vents. It is the object of the present paper
to show that in the latter case these phenomena followed a definite
order of succession, both in space and in time.

III. THe Eruptions 1n THE PHLEGRHAN FIecps.

Taking account of its aspect and its lithological characters, as
also of its stratigraphical succession, the eruptive material of the
Phlegreean Fields may be divided into three principal categories,
which in their turn include evidence of several secondary eruptive
phases. The middle division of the three, and the most easily
distinguishable, is represented by the well-known characteristic
yellow tuff of Posillipo, which forms the main framework of
the entire Phlegrzean area. The lower division consists of all the
various materials which underlie the yellow tuff, and are visible
only to a very small extent. Lastly, the upper division comprises
all the deposits of later formation than the yellow tuff. This
threefold distinction, of petrographical and stratigraphical relations
in the series of voleanic rocks in the Phlegrezan Fields, points to
three main epochs of volcanic activity. It is needless to add that
at no single point is the series to be found complete and in the
exact order of superposition. Just as the eruptive vents varied in
their output, and the subsequent activity of denuding agencies
varied also: so too, both in quality and quantity, the representative
products of each particular period are seen to be diverse. We may
consider, however, that a nearly complete type-section is available
in the artesian well of the Royal Garden at Naples, sunk in 1847
at an altitude of 79 feet above sea-level, and going down to a
depth of 7013 feet below sea-level, traversing therefore a thickness
of 7804 feet of deposits. The section, neglecting minor details, is,
in descending order, as follows :—

Feet
1. Humus, drift-material, pozzolana, and grey lapilli ... 64
2. Compactiyellow and greenish tuff... 02. ic... snctsene nee 264
3. Pozzolana, sands, sandy tuffs, pumice, volcanic breccias
and conglomerates, intermingled with clays and marls
made up also of volcanic constituents of a trachytic
FACIES}. 53, 28 sd crab waicadone destiny deinen ft SaPeERR ee oe eee netee 319
4. Pipernoid grey tuff, similar to that of Sorrento and
OAS OT ai io enc yeu eae cas gee ee ee Aa eee 88
5. Pleistocene clayey sands, with marine shells similar to
species now living in the Bay of Naples .................. 453
7803

Of the formations enumerated in the foregoing section, those
included in No. 5 most probably represent the sedimentary platform
upon which rest all the eruptive deposits of Campania. The
various and complex constituents of 3 and 4 are records of the First
eruptive Period, anterior to the yellow tuff. This last, included

Vol. 60. ] VOLCANIC ACTION IN THE PHLEGR#XAN FIELDS, 301

under 2, is the representative of the Second Period; and those
eruptive materials which are in situ, included under 1, mark the
Third Period.

We will now examine how the materials belonging to these
three successive periods are visibly represented in the Phlegraean

Fields.
(1) First Period.

The products of this period may be divided into two great
categories, corresponding to two different eruptive phases: the one,
more ancient, represented by the well-known piperno and the grey
pipernoid tuffs of Campania; the other, made up of alternating
beds of pumice, lapilli, sands, breccias, and other volcanic accumula-
tions. It will be well to bear in mind the distinction between
these two categories.

(a) Phase of the Piperno and Pipernoid Tuff.

All the broad plain of Campania and all the valleys of the neigh-
bouring calcareous massif of the Apeninnes, from those of Capri
and Sorrento to the far-off vales of Salerno, Avellino, Caserta, and
Capua, are filled, to a greater or less thickness, with a grey trachytic
tuff, in which are scattered small black scoriz, resembling in
appearance the well-known piperno, and consequently termed
‘pipernoid tuff In its present situation this pipernoid tuff is the
outcome of the heaping-up and consolidation, not only of detrital
eruptive material, transported by aérial, and perhaps also marine,
currents far from the original vents and laid down where it now
lies, but likewise of such material as was, both contemporaneously
and subsequently, washed down from the mountain-tops by running
waters and accumulated in the valleys.

The detrital constituents of which these tuffs are made up (capable
of being carried by high winds 30 miles or more away from their
origina] source), must have been so rich in hydrofluoric, hydrochlorie,
and sulphurie acids, that, helped by the action of percolating waters,
they acted upon the limestones against which they rested, and upon
such limestone-blocks as were embedded in the tuffs, inducing
extreme metamorphism therein, and thus originating the famous
fluor-bearing blocks which have been studied by A. Scacchi.!

These tuffs, as the well-sections and the natural exposures demon-
strate, rest almost directly upon the sedimentary rocks of the
Campanian basin, and consequently represent the first products of
eruption of that part of Campania. ‘They were ejected from
volcanoes and craters, which have been completely obliterated by
later geological vicissitudes, but must have been at one time
concentrated especially in the area of the Phlegrzan Fields.

See, in this connexion, Report of the Committee appointed for the Investi-
gation of the Volcanic Phenomena of Vesuvius & its Neighbourhood, drawn
up by H. J. Johnston-Lavis, Rep. Brit. Assoc. Adv. Sci. 1890 (Leeds) p. 397.
Also W. Deecke ‘ Zur Geologie von Unteritalien: § 3. Der sogenannte Cam-
panische Tuff’ Neues Jahrb. vol. ii (1891) p. 286.

302 PROF. G. DE LORENZO ON THE HISTORY oF [ Aug. 1904,

In that area, the work, both destructive and constructive, accom-
plished by later vulcanicity has been so manifold and extensive,
that it is no easy task to trace the equivalent of the pipernoid
tuffs. Nevertheless, a great mass of them has been found, as
before described, in the artesian well sunk in the Royal Garden at
Naples ; and less considerable remnants are traceable in the depres-
sion that lies between the hills of Vomero and Posillipo. Also at
Monte di Cuma, immediately above the great dome of trachyte
which forms the base of the historic acropolis, and is perhaps
contemporary with the piperno presently to be described.

Instead of the pipernoid tufts, we find exposed in the Phlegraean
Fields as their representative the celebrated piperno. This forms
the base of the Hill of the Camaldoli, and, interrupted here and
there, by later deposits of yellow tuff and grey pozzolana, may
be traced from the spurs of that hill for about a mile and a quarter
eastward into the basin of Soccavo, and for other two-thirds of a
mile northward into the basin of Pianura, divided into two beds or
layers by an intervening band of breccia.

The controversy has been a lengthy one, as to whether the
piperno should be regarded as a metamorphosed tuff or as a lava,
and even now geologists are by no means unanimous on the point.
It appears to the present writer, however, that both the geological
conditions and the petrographical characters of the piperno are
in favour of the conclusion that it is a trachytic schlieren-lava,
the dark stripes of which are made up of such minerals as augite,
egyrine, and magnetite, while the lighter groundmass is of fel-
spathic nature (anorthose), with a spherulitic structure and tiny
microliths of egyrine and augite. It is not claimed, however, that
a sharp dividing-line can be drawn between the dark schlieren
and the light groundmass.

The occurrence of the piperno at the base of the Hill of the
Camaldoli leads to the supposition that this locality, which is
practically in the very centre of the Phlegrean Fields, is also the
site of one of the principal vents from which was ejected the
pipernoid tuff of Campania. This supposition is strengthened by
the fact that at that very same spot great explosive eruptions took
place at a later period, to which the superposed bands of breccia
bear emphatic witness, not to speak of a considerable ejection of
yellow tuff. So abundant indeed was the accumulation of eruptive
material, that it served to build up the present Hill of the Camaldoli,
which, ‘despite successive demolitions and degradations, still forms
the most conspicuous elevation in the Phlegrzan Fields.

(>) Phase of the Conglomerates and Breccias.

Above the piperno and the pipernoid tuffs comes a succession
of strata diverse in character, it is true, but predominantly con-
glomeratic, and bearing visible traces of the flow of sea-currents
and of marine deposition. Whence it may be inferred that, equaliy

Vol. 60. ] VOLCANIC ACTION IN THE PHLEGRZAN FIELDS. 303

perhaps with the piperno and the pipernoid tuffs, they are the
products of submarine eruptions.

The series consists of ashes, sands, lapilli, and trachytic pumice,
often intermingled with shell-bearing clays and marls, while inter-
calated among them and overlying them are conglomerates and
coarse breccias of a thickness which varies with their proximity to,
or distance from, the vents whence they were erupted. These
breccias, to which Dr. Johnston-Lavis has applied the name of
Museum Breccias, are made up of blocks of all sizes, torn indis-
criminately from the underlying rocks, and therefore of extremely
diverse character. Among them may be noticed, as especially
abundant, blocks of obsidian, pumice, and scoriaceous trachyte ;
hardly less numerous are the fragments of leucitic and of meta-
morphosed calcareous rocks. Taken as a whole, they bear a
remarkable resemblance to the breccias of the islands of Procida
and Vivara,’ and date probably from the same period as these.

In fact, we find these deposits of sandy and clayey tuff, of
conglomerates and breccias, sometimes intercalated with deposits
of rusty-black cinders or scoriz, most typically developed in that
part of the Phlegrzan Fields which is nearest the above-mentioned
islands—that is, along the entire western base of the Monte di
Procida, and on the north-western flanks of the Monte di Cuma.
Another remarkable deposit is that which occurs below the
Camaldoli, in the shape of picturesque, precipitous, ruddy crags,
seen from afar off to be clearly based on the piperno and capped
by the yellow tuff. Noteworthy also is the great mass of these
strata, about 330 feet of which were pierced through in the
artesian boring of the Royal Garden at Naples. Finally, traces of
them have been met with below the Vomero Hill, in the course of
excavations made for the cable-railway from Montesanto to
Vomero.

It need scarcely be added that exactly-similar deposits, overlying
the pipernoid tuff, are found in the valleys of Capri, Sorrento, and
other localities in Campania. But in this paper we are concerned
only with those which lie near their source of origin, in the
Phlegrean Fields. Here, indeed, they are exposed only at a few
points, being elsewhere mantled over by the eruptive masses of the
Second and Third Periods.

(2) Second Period.

Overlying the breccias and conglomerates of the Camaldoli, of
Monte di Cuma, and of Monte di Procida, are the masses of the most
widespread and most characteristic geological formation to be seen
in the Phlegreean Fields—the yellow tuff. This tuff, characterized
by a fine cream-coloured or straw-coloured yellow tint, is a well-
compacted aggregate of ashes, lapilli, and small pumice-fragments
of trachytic nature. Scattered through this uniform matrix are

1 G. de Lorenzo & C. Riva ‘ I] Cratere di Vivara nelle Isole Flegree* Atti
R. Accad. Sci. Napoli, ser. 2, vol. x (1901) no, 8.

304 PROF. G, DE LORENZO ON THE HISTORY OF [| Aug. 1904,

fairly-numerous fragments of other tufaceous rocks and lavas, with
a few infrequent fragments of felspar and pyroxene-crystals.
Among the rock-fragments, the most prevalent is a greenish tuff,
very similar to the Epomeo tuff, which has also been met with, in
place, below the yellow tuff in the artesian well of the Royal
Garden. Trachytic black scoriw, too, are scattered abundantly
through the yellow tuff, diminishing in size as the distance of the
exposure from the vents whence they were erupted increases, and
being therefore smallest at the outermost periphery of the volcanoes.

The yellow tuff, like similar volcanic deposits, is invariably
stratified in very well-marked thin bands, coinciding with the
tectonic structure of the volcanic mass of which they form part.
This coincidence often helps the observer to reconstruct hypo-
thetically more than one volcanic edifice, which later cataclysms
have in part destroyed, or perhaps swept entirely away. The
layers, uniformly yellow, are sometimes intercalated with paler
grey bands, or, where they have been exposed to surface-alteration,
are sometimes covered with a sort of grey film. Asa rule, however,
the picturesque masses of yellow tuff stand out from afar off, and
being fissured by vertical joints, form rugged and precipitous crags,
such as may be seen, for instance, below the Camaldoli and at the
headland of Posillipo.

The eruptions of ash, lapilli, and pumice whence these masses of
yellow tuff, of an average thickness exceeding 300 feet, were
derived, were generally of an explosive character. But it seems
probable that lava-eruptions, though of rare occurrence, were not
entirely wanting ; and the products of such outbursts may well be
represented by the trachytic masses, met with in the tunnels of the
Cuman Railway and of the great Cloaca, which run beneath the
Vomero Hill.

These eruptions, like those of the First Period (pipernoid tuff and
piperno), must also have taken place under the sea. This may
be inferred from the extreme and uniform compactness of the tuff,
and from the non-remanié or unaltered shells of Ostrea, Pecten, and
other marine organisms which occur sporadically buried in the tuff,

On account of the great uniformity of this deposit, it does not
seem possible to map out any order of succession for the different
eruptive vents whence the materials of which it is built up were
derived. Geologically speaking, we may regard these eruptions as
contemporaneous manifestations of one great phase of vulcanicity
which affected the entire area of the Phlegreean Fields.

It is true that some of the volcanoes built up of yellow tuff are
better preserved than others, some of which are barely recognizable.
But this greater or less degree of preservation is not due so much
to difference of age, as to diversity of the accidents to which the
voleanoes have been subjected since their formation. Some of
them were sooner upheaved above the sea and to a higher altitude,
and were consequently exposed to longer and more destructive
atmospheric erosion. Several were broken up, or eviscerated, or
overwhelmed by later eruptions, while their neighbours escaped.

Vol. 60.] VOLCANIC ACTION IN THE PHLEGR2XAN FIELDS. 305

For these reasons, in the following rapid enumeration of the
various volcanoes built up of yellow tuff, it is thought best to
adopt a topographical arrangement.

The Volcanoes of Yellow Tuff.

The ashes, lapilli, and pumice of which this tuff is composed,
as they were erupted from various orifices scattered about the
Phlegrzean area, were heaped up around these vents in obedience
to the laws of projective energy and gravity, forming therefore sc
many cones, rather broad and flat than otherwise, with wide and
deep craters. In these cones, the material, being uniform in
character, accumulated in Jayers, the major portion of which
coincided in inclination with the external slope of the cone; while
the remainder was stratified conformably with the internal crater-
slope. This structure is in accordance with the law of the
formation of detritic voleanoes, whereof Monte Nuovo is a notable
example.

After their formation, these cones of yellow tuff, together with
the underlying rock-platform, were upheaved above the waves of
the sea, and each in turn fell a prey to the destructive agencies of
the atmosphere, which proved to be more relentless in their attack
at some points than at others. Moreover, within the area of the
Phlegrwan Fields later vents of eruption opened, (with which IL
shall deal when describing the Third Period), and by their explosive
energy rent and dislocated such of the cones of yellow tuff as lay
in their way, and overwhelmed and covered them with fresh erupted
material. Thus it is that what we now behold are the mere frag-
mentary ruins of the volcanoes of yellow tuff, and yet they form
the most important and conspicuous feature in the scenery of the
Phlegrzan Fields.

The southernmost, perhaps, of these volcanoes of yellow tuff
still submerged beneath the sea are represented by the two shoals of
Mezzogiorno and Penta Palummo, which, at distances of
1; and 22 miles respectively from Cape Miseno, rise from a depth
of some 300 feet to within 164 and 98 feet respectively from the
surface of the sea, and betray by their conical form their volcanic
origin. But we may pass on from these to the consideration
of those unmistakable volcanoes which rise above the waves.

First among them is the little Islet of Nisida, which attains a
height of 330 feet or so above the sea, while the roots of the
voleano certainly go down to at least an equivalent depth below
sea-level. The crater, into which the waves flow by a narrow
breach open to the south-west, is 360 feet deep, measures 1312 feet
round its upper rim, and +90 feet round its lower orifice. These
dimensions are almost identical with those of the crater of Monte
Nuovo, which it also resembles most strikingly in shape. The
typical yellow tuff of which it is built, is unmistakably stratified
with a quaquaversal dip along the external slope of the cone and
along the inner declivity of the crater. The tuff is crowded with

306 PROF. G, DE LORENZO ON THE HIstory oF [Aug. 1904,

big black scoriz, as is always the case in the neighbourhood of the
eruptive vents, and is mantled with a thin covering of pozzolana
and grey tuff, the products of the later eruptions of the Third
Period. The volcano of Nisida, being the smallest and the best
preserved of all those that were built up of the yellow tuff, may be
regarded as a type and a model for pursuing the study of the
remainder.

Practically joined to Nisida by small skerries of yellow tuff, the
fine hill of Posillipo towers above the sea with its perpendicular
walls some 500 feet high, and its long picturesque summit-ridge
stretching inward to Naples. This hill, as has been shown else-
where,’ represents the lateral remnants of two contiguous volcanoes,
the craters of which opened on the flats of Bagnoli and Fuorigrotta.
The western flanks of these volcanoes were demolished by later
eruptions (probably from Agnano), while their eastern slopes have
survived to form the ridge of Posillipo. In this ridge, the strata
of yellow tuff dip outward or towards the south-east. Its crest,
like that of every other Phlegrzan hill, is crowned with soft grey
tuffs and pozzolana, the varyingly-conformable and uncon-
formable superposition of which upon the yellow tuff may be well
observed in the great cuttings, and in the caves situated at Piedi-
grotta and at the outermost extremity of Posillipo, at Coroglio.

Separated from that ridge by a gentle syncline, the hills of the
Vomero, Capodimonte, and Poggioreale rise on the north-
east: they, too, are fundamentally built up of yellow tuff. The
original forms of these volcanoes, however, are not easily made out
in this case, as they have been masked by later eruptions and
demolitions, It may be that their craters corresponded more or less
to the existing curved shores of La Marinella and the Riviera di
Chiaja, and that they were divided one from the other by the crest
which even now (though in part demolished) projects from the
Vomero into the promontory of Ecchia or Pizzofalcone, and thence
into the rock-shelves and skerries of Castel dell’ Ovo, which like-
wise consist of yellow tuff. Amid the yellow tuff of the Vomero,
the excavations made for the tunnels of the Cuman Railway and
tor the great storm-water drain, have reveaJed a considerable mass
of trachyte, which bears witness to the probability of lava-erup-
tions, if not during that period, at least during the immediately-
preceding age.

The neighbouring Hill of the Camaldoli (1502 feet high),
forming the most elevated summit of the Phlegrzan Fields, is
manifestly made up, for the greater part, of yellow tuff. This is
seen on every hand below the loose grey tuffs and the pozzolana,
where these rocks have been laid open in the gullies and channels
which seam the northern flanks of the hill. The eruptive vents of
this yellow tuff were evidently situated in the two basins of Soccavo
and Pianura, which preserve to this day an unmistakable crateri-
form aspect.

" G. de Lorenzo & C. Riva ‘Il Cratere di Astroni nei Campi Flegrei’
Atti R. Accad. Sci. Napoli, ser. 2, vol. xi (1902) no. 8, p. 72 & fig. 5.

Vol. 60.. VOLCANIC ACTION IN THE PHLEGR2AN FIELDS. 307

On the other hand, it is no easy matter to trace the original
vents or apertures whence were derived the outcrops of yellow
tuff which are to be observed around the Piano di Quarto up
to its extreme northern boundary (where this is cut by the Via
Campana); or those which crop up here and there along the beach
from Bagnoli to Pozzuoli. Subsequent geological changes have
obliterated every vestige of the original craters.

Between the shore and the Piano di Quarto, however, the
voleano of the Gauro, the finest in the Phlegrean Fields, and one
of the best-preserved of those built up of the yeilow tuff, towers to
a height of 1082 feet above the sea. The cone, unbroken on the
north, was torn open on the east and west by two subsequent
outbursts, and has been worn down on the south by the rains, the
winds, and the waves of the sea, which beat against it at the time
of its emergence. If we ascend the slopes of this great cone, we
see on reaching the summit a vast crater yawning below us (hence
the epithet, which Juvenal applied to the mountain, of Gaurus
imanis), nearly 5000 feet wide and more than 650 feet deep. In
dimensions and majesty it challenges comparison with the later,
neighbouring crater of Astroni.

Of uncertain origin, again, are the outcrops of yellow tuff which
occur along the western portion of the Phlegrzan Fields, at Arco
Felice, Bacoli, ete. up to the Monte di Cuma, near the so-called
Temple of Apollo, and to the Monte di Procida, the eastern
shoulder of which is capped by them.

On the other hand, the crateriform character of the Porto di
Miseno and Cape Miseno is sufficiently obvious: they are both
made up of yellow tuff, overlain by pozzolana and scorie of
later eruption. The crater of Porto Miseno is all but drowned
by the sea, its upper rim only emerging in part. Cape Miseno, long
famous for its internal structure, laid bare on its broken-down south-
western flank, emerges to the height of 544 feet above the waves,
while its roots plunge down to 330 feet below them. Thus,
both in dimensions and in form, it is strikingly similar to the
crater of Nisida, which may be regarded as the other southern
outpost of the Phlegrean Fields.

Moreover, the form of Miseno and Nisida is paralleled by that of
Monte Gauro and the other yellow-tuff volcanoes, and this paral-
lelism of form is associated with similarity of structure and petro-
graphic composition. All of which fits in to a certain extent with
their common mode of origin, namely, submarine eruptions
taking place almost simultaneously over the entire
Phlegrean area.

A much greater, though not perhaps an extreme, diversity is
found among the later volcanoes, which arose at different points
and at different times, and almost all on land in the open air.

(3) Third Period.

It would seem that the eruptions of yellow tuff which had
fashioned almost the entire framework of the Phlegrwan Fields

308 PROF. G. DE LORENZO ON THE HISTORY oF [ Aug. 1904,

were immediately succeeded by an uplift of the whole region, and
this by a somewhat lengthy period of erosion; for the later
materials are everywhere, not only deposited (some-
times conformably, sometimes unconformably) upon
the eroded surface of the yellow tuff, but are evidently
derived on the whole from subaérial eruptions.

Thus, we no longer find in these later deposits that uniformity
of composition which characterizes the yellow tuff, although they
also consist predominantly of fragmental materials of a trachy-
andesitic character. They show, however, both macroscopically
and microscopically, a certain diversity, according to the particular
eruptive vent from which any given material was derived.

Moreover, we are no longer dealing with contemporaneous
eruptive vents, scattered, with some approach to regularity, over a
vast area, as was the case with the vents whence issued the
materials of the yellow tuff; but we can trace a distinct succession,
both in time and space, with a progressive limitation and a slow
diminution of vulcanicity, all preluding the moribund stage or
perhaps final extinction of voleanic activity in the entire Phlegraan
area.

In the succession of eruptive vents here, as is the general rule
with volcanoes, a primary big vent is followed by one or more of
progressively-diminishing size, a diminution accompanied by a
slight shifting of the axis of eruptivity. This shifting has been
sometimes confined within the circumference of the original crater-
rim, and we get as a result a system of concentric craters, or
crateri a recinto, as, for example: Agnano—Astroni—and the
internal craters of Astroni. At other times, the shifting has been
excentric, instead of concentric; and this has resulted in a series
of parasitic cones on the outside of the first, as, for example,
Astroni—craters of Campana; or Astroni—Cigliano. In other
cases, finally, the shifting of the axis of eruptivity has been so
considerable, as to leave no point of contact between the new and
the old voleano, and to give rise to entirely-different systems, as,
for example, Astroni and Monte Nuovo. I propose to enumerate
these different volcanic systems of the Third Period, beginning
with the oldest and ending with the most recent; and, wherever
possible, to show an order of succession between widely-distant and
often mutually-independent eruptive vents.

Around each such vent the generally-fragmental material was
heaped up in the same manner as that described in connection with
the vellow-tuff volcanoes. That is, crateriform girdles were built
up, wherein the layers dipped centrifugally outward, and in part
centripetally inward. The materials of these cones have a
generally greyish tinge, and are much looser in texture than those
which constitute the yellow tuff, from which they are therefore
easily distinguishable. On the other hand, it is not easy to
distinguish, one from the other, the products of the various volcanoes
of the Third Period. Consequently, at those localities which are at

Vol. 60. | VOLCANIC ACTION IN THE PHLEGRAsAN FIELDS, 309

some distance from the eruptive vents, and where the material has
been spread out and distributed uniformly by the winds and the
dynamic force of the outbursts, it is only possible to speak of ashes,
lapilli, pumice, and tuffs as promiscuously derived from the central
volcanoes. In a few instances only, as, for example, in the case of
a small layer of manganiferous purplish ash, which occurs on the
summit of the Hill of the Camaldoli and at some other localities in
‘the Phlegrzan Fields, can it be said that this particular deposit has
been derived from the Astroni eruptions: the evidence for this
identification being the existence, in the walls of the Astroni crater,
of a thicker band of the same ash.’ In the same manner, we may
conclude that the loosely-textured grey material which almost every-
where caps the hills of yellow tuff (and is known to the quarrymen
as mappamonte) is no product of disintegration or aqueous
erosion, but is on the whole directly derived from the central grey-
tuff volcanoes of the Phlegrzean Fields.

Not always, however, did the eruptive vents of the Third Period
discharge a quantity of material sufficient to build up true crateri-
form cones, on the type of Agnano, Astroni, Cigliano, Monte
Nuovo, etc. Sometimes the outbursts merely rent asunder the
ancient deposits of yellow tuff, forming in them ‘craters of
explosion, round the rims of which the scanty products of the
outburst accumulated. Such are the circular or semicircular cavities
which occur dispersedly in the Phiegrzan Fields. Thus, from the
colossal example of the Piano di Quarto, with a maximum
diameter of 24 miles, we may pass to the Piano di Torre
Poerio (north of Astroni and east of the Craters of Campana), to
the Piano di Teano (south-west of Monte Gauro), and thence
to yet others, until we reach Avernus, the most typical of all
these craters of explosion. This too, almost alone among those
of the Phlegrean Fields, has furnished, besides the authigenous
material erupted from it, scoriz and blocks of leucotephrite which
now form a small band among the layers of fragmental material
on its northern flank.

Of course, pari passu with the shifting of the axis of eruptivity
the craters of accumulation have occasionaJly alternated with those
of explosion. Consequently, if we endeavour to establish a chrono-
logical sequence among the central volcanoes of the Phlegraan
Fields, we must take account of both categories. A sequence of
this kind, as I have said before, can only be determined with a
comparative amount of relative certainty. One series, for instance,
is exemplified by the contemporaneous craters of Posillipo, Soccavo,
or Pianura, with which are successively and concentrically asso-
ciated the craters of Agnano and Astroni, and the internal cone of
the latter.

Another sequence, concentric also, may well be represented by
the crater of Pianura, the explosion-crater of Torre Poerio, the

1 G. de Lorenzo & C. Riva ‘Il Cratere di Astroni nei Campi Flecrei’ Atti
R. Accad. Sci. Napoli, ser. 2, vol. xi (1902) no. 8, pp. 22-28.

310 PROF. G. DE LORENZO ON THE HISTORY oF ([ Aug. 1904,

crater of accumulation of Astroni and its internal cones. A third
sequence, in part excentric and in part concentric, is furnished by
Monte Gauro, the explosion-crater of Teano, and those of Avernus
and Monte Nuovo. Excentric sequences, on the other hand, are
exemplified in the crater of Astroni, as well as in the volcanoes of
Ciglhano and Campana which have arisen on its shoulder; and
similarly in the volcano of Monte Gauro, with the subsidiary cones
of Concola and Fondo Riccio, which are placed parasitically on its
western flanks.

All these concordant sequences demonstrate, not
only that eruptive activity was gradually diminish-
ing, but that it was in general contracting towards
the centre of the volcanic area; or rather, that it was
shifting southward and seaward, receiving from the
waters of the ocean the kinetic factor, steam.

But, leaving aside these theoretical considerations, it may be well
to describe as briefly as possible the chief among the latest voleanoes
of the Phlegrean Fields.

The Volcanoes of Grey Tuff.

The greatest and most ancient of the third series of the volcanoes
of the Phlegreean Fields is that of Agnano. Its broad and deep
crater, about 137 miles across, is all but intact on the east, but is
partly demolished and partly masked on the west by later outbursts,
such as those which have originated the successive volcanoes of
Astroni and the Solfatara. The materials of which Agnano is built
up, like those of the later volcanoes, consist mainly of layers of
pumice, ashes, lapilli, and soft grey tuffs, among which, on the
eastern and southern flanks (Monte Spina), are also intercalated
beds of scorize. With this voleano we may too, in all probability,
associate the great mass of trachy-andesitic lava of Caprara,
which, torn asunder and then mantled over by the later eruptions
of Astroni, 1s now involved in the eastern flank of the last-named
voleano. From the internal eastern flanks of Agnano thermal
mineral springs well forth in great abundance. These are now
canalized, and debouch by artificial channels into the sea. But
about fifty years ago they united to form at the bottom of the crater
a broad and shallow lake, wherein was deposited the detritus carried
down from the slopes by rainwash. It was in consequence of the
occurrence of these thermal springs, and of the exhalations of steam
and gas associated with them, that the ancient Romans created here
great baths, which might be successfully restored.

West of Agnano arise the volcanoes of Astroni and the
Solfatara, the relative antiquity of which it is at present
impossible to determine. The materials of the Solfatara have been
completely altered by copious gaseous exhalations. Now, as such
altered materials are seen underlying those of Astroni, it may be
reasonably argued that the earlier eruptions of the Solfatara were

Vol. 60. ] VOLCANIC ACTION IN THE PHLEGRHAN FIELDS, 311

perhaps anterior in date to those of Astroni. Whereas, however,
the great cone of Astroni was thrown up, as it were, with one
spurt and finished off in a single gigantic though brief spasm of
eruptivity, followed by a few ejections of ashes and scorie, and by
one scanty outflow of lava in the central portion of the crater:
the voleano of Solfatara, on the other hand, remained active
throughout a long period, giving rise to small outbursts of lava
within the crater itself, and to great trachytic flows which coursed
down its southern flanks as far as the sea, there forming the
Monte Olibano. In the Middle Ages incandescent lava was still
to be seen in the crater of Solfatara, and even at the present day
its temperature is higher than that of any other eruptive vent in
the Phlegreean Fields. To this long continuance is due the intense
alteration, which the gases customarily occurring in fumaroles have
induced in the materials of which the volcano is built up, in such
wise that it forms an unique instance in the Phlegrean area. The
very persistence of this activity, primarily eruptive and subsequently
solfataric, leads to the inference that a local magmatic basin, larger
_ than those of the neighbouring vents, exists beneath the Solfatara.
This supposition is confirmed by the relatively-greater quantity
of lava ejected from this vent than that poured out from the
other voleanoes of the Phlegrean Fields, which are, indeed, pre-
dominantly built up of fragmental materials. Generally speaking,
volcanoes of detritic or of tufaceous type represent the
outcome of rapid and violent explosive action, and hence
they have a much shorter life than volcanoes of the type which is
mainly lavaform or mixed.

On the external north-western slopes of the great crater of
Astroni two small adventitious or parasitic volcanoes are to beseen:
Cigliano and Campana. The first-named is a simple cone,
with a crater eroded on the south by the action of winds and rains
upon the friable material of which the cone is wholly built up (ashes
and small pumice). The volcano of Campana, on the other hand,
belongs to the concentric type (vulcano a recinto), being made
up of three practically-concentric rings, within the innermost of which
is a small but most beautiful crater, rent on the east by a deep and
narrow fissure known as La Senga. ‘These three ‘girdle-craters’
of Campana consist of but little ash and lapilli, with a vast mass of
scoriz and bombs, red and black, of trachy-andesitic character, and
increasing in quantity inwards in such wise that the latest crater.
called the Fossa Lupara, may be said to be entirely composed
of blocks of lava. It seems probable that the rending-open of the
fissure of La Senga was brought about by the settling-down and
cooling of these blocks.

Of practically the same type as Cigliano, that is, almost wholly
built up of ashes and pumice, with a few infrequent scorie, is 2 tiny,
barely perceptible vuleanetto, known as Santa Teresa, which
lies on the plain of Bagnoli, south-east of the outer slopes of Agnano,
Here, too, as on Cighano, the rain-laden southerly winds have

312 PROF. G. DE LORENZO ON THE HISTORY oF . [ Aug. 1904,

broken down and swept away the southern wall of the crater,
only the northern part remaining as a crescent-shaped ridge.
Little tufaceous hillocks, like that of Santa Teresa, occur at other
localities in the Phlegraean Fields, as, for example, the Hill of the
Crisci, between Cighano and Campana. But they have been so
greatly denuded that it is no longer possible to determine whether
they are the outcome of single eruptive outbursts, or represent
remnants left from the erosion of neighbouring craters.

Volcanic deposits of the same type as those of the Campana craters,
that is, made up chiefly of red and black scori# and bombs, inter-
mingled with fragments of pinkish-yellow tuff, are found dispersedly
in the Phlegrzean Fields. They invariably overlie the yellow tuff, and
underlie the series of grey ashes, lapilli, and tuffs. These deposits
are typically massed on the western and northern slopes of the
Gauro volcano, forming the so-called Concola and the little
voleano of Fondo Riccio. They constitute also the great fan
of red and black scoriz which occurs on the Cleft Mountain
or Montagna Spaccata, where the ancient Via Campana runs
through a deep cutting into the Piano di Quarto. Again, they are
found north-east of the city of Naples, on the eastern slopes of
Capodimonte, and at Santa Maria del Pianto and the
Ponti Rossi. Yet although, as I have already pointed out, these
deposits are lithologically very similar indeed to those of the
Campana craters, they must be of much greater age, as is indicated
by their structure and by their invariable infraposition below the
grey tuff. At La Concola and the Fondo Riccio, the form of the
crater from which they were derived may still be traced; on the
other hand, not a vestige of it remains among the scoriaceous masses
of Santa Maria del Pianto and the Ponti Rossi. The scoriz of the
Montagna Spaccata must have been either contemporaneous with, or
of but little later date than, the explosions which gave rise to the
great basin that lies east of Monte Gauro, which was _ possibly
anterior to the crater of Astroni and to that of Agnano.

It is no easy matter, however, to determine the precise strati-
graphical and chronological relations either of these scoriaceous
volcanoes, or of the tuff-voleanoes which range in a direct north-
and-south line, west of Monte Gauro and Monte Nuovo, from
Monte Ruscello to Bacoli.

The northernmost eminence along this line, Monte Ruscello,
is followed southward by a crater-ring known as Monte Grillo,
which encircles the later explosive crater of Avernus, this again
engirdliing Monte Nuovo, the latest voleano of the series and of
the entire Phlegrean Fields. South of Baia is yet another little
crater of grey tuff, known as Fondi di Baia.

Naturally, the most important of the whole of this series is the
crater-lake of Avernus, not only because of its dimensions and
depth, but because, alone among the volcanoes of the Phlegrean
area, it erupted, besides the customary ashes, lapilli, pumice,
scoria, and blocks of the underlying yellow tuff, small scoriz of

senses ssenneneeeeneneee

/

Vol. 60.| VOLCANIC ACTION IN THE PHLEGRHAN FIELDS, 313

-leucotephrite, with fine crystals of leucite, which now form a thin

stratum in the upper part of the northern flank of the crater.
Up to a height of about 130 feet the crater of Avernus is filled
with fresh water, which one day perchance percolating below ground
fed the thermal springs of Tripergola, and there in September 1538
initiated the outburst of Monte Nuovo. This eruption, with its
ejectamenta of ash, lapilli, pumice, and lastly phonolitic scorie,
forms for the present the closing chapter in the history of vul-
canicity in the Phlegrean Fields. With a certain amount of
hesitation and uncertainty I may, perhaps, venture to summarize
that history in the following table :—

ScHEMATIC SYNOPSIS OF VULCANICITY IN THE PHLEGRHAN FIELDs.

|
i

i
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Q.J.G.8. No. 239. ¥

|
|

.
Piperno. Trachyte of Coma. |

a. Ss S Eruptions of ash, lapitli, ‘Kraptins dp
SS & | i pumice, and other iaists aid oie
ae | a | detritic materials. ,
- ae ae :
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Nuovo. )
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| | 2
: | Fondi di Baia. [ =
1 | | | | Se
a i ———. —— S
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= | a | | B°%E=S)/ 22 « Leucotephrite of Avernus.
oP S| Bgsde| 575 2 ee ee
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= | = | Monte Grillo. | 2:5 22-2 | 22° & | Lavas and scorie of Monte |
= = 23 20 |S £ | Ohbano, of the internal cones |
= = | Monte Ruscello| =4£22|2.2 5 | of Astroni, and of the craters |
~ =n }acle14h°8 S | of Campana.
2 oe | ‘= oo
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| Pianura, Quarto, Teano, etc. | Pianto, Ponti Rossi. =="
oe? | | yeah ee Pelee oe
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| Yellow tuff of Nisida, Posillipo, | (?) Trachytic masses
ao Vomero, Capodimonte, the Camal- met with in the
a5 doli, Gauro, Pozzuoli, Quarto, | various tunnels
oy po Monte di Cuma, Procida, Porto | under the Vomero
Bs Miseno, Capo Miseno, etc. Hill.
ma”. | cient
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alley Breccias and conglomerates of the | Scoriaceous lavas and scoriz |
ais : Camaldoli, Cuma, Monte di Pro- | of Monte di Procida, Monte |
n= $= cida, Monte Santo, etc. | di Cuma, ete.
= S |
|

314 PROF, G. DE LORENZO ON THE HISTORY OF [ Aug. 1904,

LV. ConcLvusIons.

We have seen that, in the Bay of Naples, towards the end of the
Pliocene and the beginning of the Pleistocene Period, while the
Apennine chain was in process of uplift, eruptive phenomena which
were then happening beneath the waves of the sea, over an area
of local dislocation, laid the foundation of the volcanic districts
that now encircle the city of Naples.

In that part of the region which is known as the Phlegrean
Fields, we now behold a continuous succession of voleanic forma-
tions, the lowermost of which bear unmistakable signs of a
submarine origin, while the upper deposits are just as undoubtedly
of subaérial origm. The earlier deposits bear witness to phe-
nomena of a more widespread character and of more grandiose
dimensions; the later testify to a gradual diminution, both in
extent and intensity, of volcanic activity.

The lowermost of these deposits of the Phlegreean Fields are the
lavas and pipernoid tuffs which may be correlated with the grey
tuffs that constitute the entire platform of Campania. These are
followed by a series of breccias, conglomerates, and layers of
scorie ; and the whole of this earlier submarine series is overlain
by the great masses of yellow tuff, which form the framework of
all the hills between Naples and Cuma.

The eruption of yellow tuff was followed by an uplift, and by
prolonged denudation. Later began a series of subaérial eruptions,
the products of which were chiefly ashes, lapilli, and pumice (more
or less loosely compacted to form grey tufts), and also a few lavas
of trachy-andesitic character.

These subaérial eruptions took place over a more limited area,
internal to, and shifted more southward and seaward than, the
earlier eruptions. Not only was there this distinction, but the
several volcanoes of the second series diminished gradually in
intensity and extension, although this diminution was fitful rather
than regular. They began with the great outbursts of the enor-
mous ancient crater of Agnano, and died out in the paroxysm of
Monte Nuovo.

In this manner the volcanic fires which, towards the beginning
of the Pleistocene Period, glowed with such intensity over the
entire Phlegrsean area, are now confined to a few localities on its
southern shore-line ; and eruptive energy has shifted its centre a
little farther southward, to Vesuvius. Volcanic action, which is
always associated with orogenic movements, has in this case also
followed upon the uplift of the Apennines: an uplift which,
beginning in the north, has been subsequently prolonged and
slackened off southward. ‘Thus the subterranean fires which first
kindled the volcanoes of the Tuscan Maremma and the Agro
Romano, passing on by the Islands to the Phlegreean Fields and
Vesuvius, have now travelled farther south, to the flaming A¢olian
Isles, and snowy Aitna, the pillar of heaven.

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Vol.60.] | VOLCANIC ACTION IN THE PHLEGRHAN FIELDs, 315

EXPLANATION OF PLATES XXVI-XXVIII.
[Altitudes and soundings are expressed in metres. ]

Piate XXVI.
Geological sketch-map of the Bay of Naples, on the scale of 1 : 500,000.

Priate XXVIII.

Sections across the Bay of Naples, on the scale of 1: 500,000; and sections
across the Phlegrzan Fields, on the scale of 1 : 100,000.

Prate XXVIII.
Geological sketch-map of the Phlegrzean Fields, on the scale of 1 : 100.000.

Discussion.

The PrestpEnr said that he was glad to find that, owing to the
application of modern methods of research, as carried out in this
paper, and notwithstanding the increase of our knowledge of
vuleanicity derived from such eruptions as those of Krakatoa and
Tarawera, these only supplemented and did not supersede the
teachings of the classical areas of the Mediterranean, including the
Phlegrwan Fields. It was a graceful act of the Author to send his
paper to the Geological Society of a country, the geologists of
which—notably Sir Wiliam Hamilton and Sir Charles Lyell—had
contributed so much to our knowledge of the Phlegrzan Fields.

Sir ARcHIBALD GeErkKIe stated that, during the spring of last year,
he had had an opportunity of making a number of traverses of the
Phlegrzean Fields with the Author, and had been so much impressed
with the minuteness and breadth of his knowledge of the volcanic
history of the district, that he urged him to prepare a succinct
statement of this history which could be communicated to the
Geoiogical Society. The paper read this evening was the result of
this request. It was a grievous loss to science when Prof. Carlo
Riva, who had been associated with the Author in the preparation
of two admirable detailed memoirs on portions of the Phlegrzean
Fields, met his tragic death two years ago. But it was hoped that
Prof. De Lorenzo would himself continue the work which had been
so auspiciously begun. The speaker pointed out the interesting
similarity, between the sequence of volcanic events in the Neapolitan,
and that in the Roman Campagna. In the latter area, the earliest
eruptions, as shown by the remarkable sections laid open by the
side of the Tiber to the north of Rome, took place in the Pliocene
sea, probably from many submarine vents; while the latest were
all subaérial, and piled up the huge cones of the Alban Hill and
Bracciano. While rambling over the Roman Campagna, he (the
speaker) had not been able to trace out three periods of volcanic
activity, and had not found any satisfactory equivalent of the yellow
tuff which makes so conspicuous a feature in the Neapolitan region.
Two periods of eruption, however, submarine and subaérial, were
well-developed, and possibly more detailed investigation and com-
parison might show the parallelism between the two areas to be
even closer than it appeared.

¥2

316 DR. C, S. DU RICHE PRELLER ON THE (Aug. 1904,

20. PHENoMENA bearing upon the Aan of the Laxe of Guneva.
By C. 8. Du Ricut Pretize, M.A., Ph.D., A.M.LC.E., M.LE.E.,
F.R.S.E., F.G.8S. (Read May 11th, 1904.)

[ Abstract. }

Fottowrne up his investigations concerning the age of the
principal Alpine lake-basins, the Author has, during a recent
prolonged stay on the Lake of Geneva, examined the low-level
gravel-beds and other alluvia in the Rhone Valley, from Geneva
to the Jura-bar near Fort de l’Ecluse, as well as the high-level
gravel-beds of La Cote above Rolle and of the Jorat district above
Lausanne, and, further, the rock-formations on both sides of the
lake, in view of evidence of flexures as the primary cause of
the formation of the present deep lake-basin.

After describing the phenomena around the Lake of Geneva, and
comparing them with those around the Lake of Zurich, he is led to
the following conclusions :—

(1) The low-level gravel-beds of the Rhone Valley near Geneva,
overlying the Molasse and underlying the glacial alluvia,
are, like the deep-level gravel-beds of the Limmat Valley
near Zurich, fluviatile deposits of the second Interglacial -
Period, and were formed before the present deep lake-basin
came into existence.

(2) The high-level gravel-beds of La Cote above Rolle and of the
Jorat district above Lausanne are, like the corresponding
deposits of the Uetliberg near Zurich, and of the Dombes and
of Lyons, true Deckenschotter. Hence the term alluvion
ancienne should, in its proper acceptation, only apply to
the high-level deposits.

(3) The formation of the present deep lake-basin of Geneva was,
like that of Zurich, primarily due to the lowering of the
valley-floor by flexures of the Molasse and its contact-
zones, posterior to the maximum glaciation, as evidenced
more especially by the reverse dip of the old erosion-
terraces between Lausanne, Vevey, and Clarens.

The Author holds that the concord of evidence in the two cases
strengthens the conclusion, already arrived at by analogy in his
previous paper, that the Lake of Geneva, together with the other
principal zonal lakes between the Alps and the Jura, was formed
under similar conditions and at the same time as the Lake of
Zurich, that is, towards the close of the Glacial Period ; indeed, the

' Quart. Journ. Geol. Soc. vol. lx (1904) p. 65.

~

Vol. 60. } AGE OF THE LAKE OF GENEVA. 317

phenomena in support of that view are, in the case of the Lake
of Geneva, on a grander scale, more striking, and, if anything,
even more conclusive.

Discussion.

Prof. Cart Scamipt remarked that the parallelism claimed by the
Author as existing between the Lakes of Zurich and Geneva was
not very clear to him: the formation of the first-named lake, at
right angles to the strike of the Molasse-country, was easier to
explain than that of the last-named lake. In his opinion, the
structure of the Lake of Geneva might be more nearly compared
with that of Lucerne: the development of the glacial formations
was very similar in the two cases. He pointed out the increasing
difficulty experienced in distinguishing the three formations of
Schotter as one approached the Alps, and he agreed with Lugeon,
Schardt. and other observers in regard to the uncertainty which
attended this question. He commented on the fluctuation of opinion
concerning the flexures of the Molasse, and observed that there
seemed to be nowadays a tendency to revert to the older theories.

Prof. Bonney thought that the comparison of the Jakes in the
same Alpine zone could not fail to bring about valuable results.
He had examined, in August 1891, the section below Geneva, to
which the Author referred, and now read some extracts from notes
written on the spot. At that time he was thinking more about the
hypothesis of glacial excavation for the lake, than of the date of its
formation. What he then saw, as these extracts showed, had con-
vinced him that the gravels on either side of the Rhone must have
been formed by that river and not by the Arve alone; that ice had
subsequently passed over them, without any appreciable disturbance ;
and that the pebbles were too much rounded to have been formed
by torrents flowing from the end of a glacier near at hand,—they
must have travelled at least several miles. Since that date he had
examined, sometimes under the Author’s guidance, the gravels and
morainic deposits in the Limmat Valley and elsewhere, with the
result that the late date of the Alpine lakes had been gradually
forced upon his mind. He realized, as plainly as any one could do,
that this was a startling conclusion, but we must remember that the
North American lakes showed that there had been considerable
movements in comparatively-recent times, and this was not the only
instance which might be quoted.

Posrcript To THE DiscussIon.

(The AvrHor, not having been present at the discussion, wishes
to point out that Prof. Schmidt’s opinion that the structure of
the Lake of Geneva may be more nearly compared with that of
Lucerne than with that of Zurich, is invalidated by the physio-
graphical fact that the Lakes of Zurich and Geneva each lie in

318 THE AGE OF THE LAKE OF GENEVA. [Aug. 1904,

one continuous, previously-eroded river-valley; whereas the Lake
of Lucerne lies in two transverse valleys composed of four different
troughs, and therefore exhibits, not unlike the Lake of Lugano, a
far more complicated structure than other lake-basins within the
same zone. The Author fully agrees with Prof. Bonney that the
bulk of the low-level gravel-beds underlying the post-Glacial and
Glacial alluvia near and below Geneva is derived from the drainage-
area of the Rhone Valley: apart from the pebbles of crystalline
and sedimentary rocks, as well as of Nagelfluh, of that watershed,
this is evidenced more especially by the striking abundance of
the Valais gabbro and serpentine (from the Bagne and Saas Valleys),
as well as of the green (Tavayanaz) sandstone of Diablerets ; that is,
of material transported and deposited, not by the Arve, but by the
Rhone.—May 21st, 1904. |

Vol. 60.] THE VALLEY OF THE TEIGN. 319

21. The Vattey of the Teten. By Atrrep Joun Jukes-Browne, Esq.,
B.A., F.G.S. (Read March 9th, 1904.)

Tue problem of the Teign Valley attracted my attention soon
after I came to live in Devonshire; and I have lost no opportunity
of considering it from different points of view, both in the study
and in the field. The following pages are the outcome of this
consideration, and constitute an attempt to explain the peculiar
course which the river takes in passing from its sources on Dart-
moor to the sea at Teignmouth.

The Teign Valley is, in fact, one of the most remarkable in the
British Islands, because it is not a simple transverse valley, nor a
longitudinal one between more or less parallel ridges, nor does it
take such a course as the general slope or gradient of the country
below its sources would suggest. On the contrary, although the
earlier part of its course is in accordance with this general gradient,
it afterwards takes a curve which leads it to run at right angles to
its primary direction, and to traverse a depression which has the
aspect of a longitudinal valley. From this it debouches into a
plain; and in this plain it again turns at right angles, to pass
through a gap which is clearly a transverse valley excavated out of
the ridge that borders the seaward side of the longitudinal valley.
This gap is now occupied by the estuary of the Teign.

As might be imagined, a valley which exhibits so curious a
succession of changes presents also a variety of physical features,
different parts of its course contrasting strongly with one another
in this respect. The head-waters of the river are called the North
Teign, and have their sources in the north-eastern part of Dartmoor,
among the characteristic scenery of that district. From the high
level of this area (above 1200 feet), it descends through a gorge into
what has been called the Chagford Basin. Though not exactly
a basin, the valley here widens out in a peculiar manner. In its
eastern part, the contour-line of 600 feet recedes for some distance
on both sides of the river, along a depression which crosses the
valley from north-west to south-east; while the rim of the area is
from 800 to 1000 feet above the sea, except at one place. The
river, however, does not escape from this depression at the point
where the rim is lowest, but through one of the highest parts
of the rim and opposite the point where it enters. Here, also,
the river leaves the granite, and has cut a deep gorge through the
band of indurated Culm-Measures which borders the northern side
of Dartmoor.

The gorge of the Teign runs in an easterly direction for about
34 miles, and the river descends about 160 feet in this distance,
that is, from about 430 to 270 feet. The gorge then bends to
the south-east and continues for another 2 miles, the stream falling
another 64 feet in that distance. Emerging from this deep and
picturesque ravine, the river takes another short turn to the east,

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Vol. 60. | THE VALLEY OF THE TEIGN. 321

and then bends southward to pursue a course which brings it
between the outermost granitic ridge on the one hand, and the
Haldon Hills on the other hand. Its valley here is broad and
open.

oiicac Chudleigh Knighton the Teign enters the plain of the
Bovey Eocene deposits, and flows over this to Newton Abbot,
where it receives the waters of the Bovey and the Lemmon; but,
instead of continuing to run southward into Tor Bay, as the present
features of the country would lead everyone to expect that it would
have done, it turns abruptly to the east, and enters the gap in which
its estuary now lies.

Such are the facts which have to be explained; and the problem
is certainly not to be solved from a mere study of maps, nor from a
cursory examination of the physical features of the district. It
does not take long to perceive that the gap of the Teign estuary is
very probably part of an ancient river-valley, excavated before the
present physical features of the surrounding country had been
developed. It may also be surmised that such a transverse cut
is not likely to have been made by the Teign, if that river has
always pursued its present course; but it is not so easy to
determine what river or rivers can have made the valley of the
Teign estuary, or how the modern Teign came to take the erratic
course above described. The problem is also complicated by the
local crust-movement which produced the Bovey Basin, although, as
will be seen in the sequel, I do not think that the synclinal trough
of this basin is so local as it appears to be.

This problem of the Teign Valley has interested many local
geologists and observers, but has not yet received what appears to
me a satisfactory explanation.

In 1867 G. W. Ormerod noticed some of the peculiarities of the
Teign Valley in the pages of this Journal’; he recorded the
presence of ancient gravels with granite-pebbles along the upper
valley, and for a short distance within the gorge of the Teign
(as far as Wootton Castle above Clifford Bridge), and he com-
mented on the absence of any such ‘old gravels’ along the further
course of the river. His explanation of the facts was that the
whole gorge of the Teign was of comparatively-recent formation,
and that the original course of the river was through the gap in
the rim of the Chagford Basin, which I have already mentioned.
His theory was, therefore, that the present valley of the Wray
Brook (see fig. 1, p. 320) is the ancient valley of the Teign, and
that the gorge of the Teign was opened subsequently by some
‘disruption of the Carboniferous rocks since the gravels were
deposited.” The idea of such a disruption is not in accord with
modern methods of interpretation ; and Ormerod’s theory can
hardly be adopted now, because if the river ever followed such
a course as he suggested, one cannot see any reason why it should

2 Quart. Journ. Geol. Soc. vol. xxiii (1867) p. 418.

19) t .
322 MR. A. J. JUKES-BROWNE ON (Aug. 1904,

have abandoned it, and consequently the hypothesis fails to account
for the deeply-cut gorge of the Teign.

A theory exists that the Teign once flowed southward by Kings-
kerswell into Tor Bay, and it has been attributed to Mr. J. H. Key;
but this appears to be a mistake, for Mr. Key only pointed out’
that, if the Bovey deposits were formed in a lake on the site of the
present basin (as he supposed they were), the overflow of this
lake must have been in the direction of Torquay. William Pengelly
made a similar statement in 18637; but thought it far more likely |
that the overflow was through the present valley towards Teign-
mouth. Neither of the writers just quoted said anything about the
River Teign ever having run into Tor Bay, and I think that the
idea of its having done so is in the highest degree improbable.

In the years 1901 and 1902, Mr. A. Somervail published several
short notes on the valley of the Teign,* and in the last of them
he concludes that ‘the river Teign, or the Teign as we now
know it, had not its present course marked out until long after the
Oligocene’; but he does not discuss its ancient course. He refers
to, and dissents from, the theory that the Teign once flowed along
the Tor Valley into Tor Bay.

Still more recently, Mr. H. J. Lowe has written on ‘The Teign
Valley & its Geological Problems.’* He describes and discusses
the curious basin-like depression through which the river flows
between Chagford and Hunts Tor, considers but rejects the idea
that it has ever been a lake, and attributes its formation to a more
rapid local decay and disintegration of the granite; he dissents
from Ormerod’s view that the Teign originally ran out of this
basin by Moretonhampstead, and concludes that its exit has always
been in the direction which it now takes. He remarks :

‘If the river has, for the most part of its existence, followed in the main its
present course, it is necessary to assume that it originally took this direction
because the head-waters found a natural discharge this way along the most
available slope to the sea. But this must have been many hundreds of feet
above the level at which it at present runs.’

With this remark I cordially agree, and I think that, if Mr. Lowe
had followed out this line of thought, he would probably have come
to the conclusion that the course which the Teign now takes beyond
this gorge is not likely to have been its original one.

It is certain that, before we can arrive at any satisfactory
explanation of the facts, we must consider the probable conditions
of the ancient surface out of which the present surface has been
developed, to what extent the older rocks around Dartmoor may
then have been covered by newer deposits, and what changes have
been (or may have been) accomplished between that time and the
present.

1 Quart. Journ. Geol. Soe. vol. xviii (1862) p. 16.

2 «The Lignite of Bovey Tracey ’ 1863, p. 19.

3 Trans. Devon. Assce. vol. xxiii (1901) pp. 517 & 521; and ¢bid. vol. xxxiv
(1902) p. 528. 4 Ibid. vol. xxxv (1903) p. 631.

Vol. 60. | THE VALLEY OF THE TEIGN. 323

For the date of our ancient surface we need not go farther back
than the close of the Eocene Period, because it is evident, from the
manner in which the Teign crosses the Eocene of the Bovey Basin,
that its valley is of later date than the Kocene Period. We may
reasonably conclude that it was at the beginning of Oligo-
cene time that the present river-system of Devonshire
was initiated.

I will next endeavour to picture the probable aspect of the
surface of this part of England in Eocene and Oligocene times, and
to estimate the extent to which it was then covered by Neozoic
deposits. It is not necessary for our present purpose to consider
how far the Jurassic rocks may have extended over Devonshire,
because we know that they were subsequently truncated and over-
stepped by the Cretaceous strata ; but these latter have certainly to
be considered.

We know that the sea of the Selbornian Sands (=‘ Upper Green-
sand’) covered what are now the Haldon Hills, and must have
stretched to the borders of Dartmoor. The deeper sea of the
Upper Chalk must have covered a still larger area, and would have
covered the greater part of Dartmoor, unless the relative levels
of Dartmoor and the Haldons have been greatly altered since
Cretaceous time, a contingency which is very probable. At the
close of the Cretaceous Period, the West of England appears to
have been raised above the sea-level, and the whole of Devonshire
must have been subjected to the detrition of subaérial agents
during the time represented by the break between the Cretaceous
and the Eocene and by the duration of the Lower Eocene Epoch.
That the granite of Dartmoor was then exposed we know, from the
frequent fragments of granite and tourmaline-rock in the Haldon
gravels.

The Eocene subsidence at length carried the lacustrine area
of the Bournemouth Beds westward over the whole of Eastern
Devonshire and over the Haldon Hills, which rise to more than
800 feet above the sea. Mr. H. B. Woodward has recorded the
existence of deposits which closely resemble those of the Bovey
Basin between Axminster and Lyme Regis, at an elevation of
400 feet." They consist of rough flint-and- “chert gravel, fine white
sand, with white and mottled clays, and they are most probably of
Eocene age. Similar gravels and tracts of stony clay (mapped as
Clay-with-Flints) cap 4he tops of the many ridges which lead up
from the coastal cliffs to the Blackdown Hills, and they occur also
on these hills at levels of between 800 and 900 feet. Mr. W. A.
E. Ussher informs me that some of the patches of clay at such
levels near Otterford, Churchstanton, and Burnworthy not im-
probably include remnants of Eocene beds in situ.

A plain prolonged westward from the summits of the Blackdown
Hills would pass over all the central part of Devonshire between
Dartmoor and Exmoor; and as part of such a plain still remains

* Summ. Progr. Geol. Surv. for 1901, pp. 53-59 ; and Rep. Brit. Assoc.
902 (Belfast) p. 601.

324 MR. A. J. SUKES-BROWNE ON (Aug. 1904,

on the Haldon Hills, we may reasonably conclude that the Kocene
deposits did cover this central area. ‘There is indeed some positive
evidence, as will be mentioned on a future page, that this was the
case. :

As no patches of Chalk remain on the Blackdown or the Haldon
Hills, and as the Eocene gravels there rest directly upon the
Selbornian Sands, it is evident that most, if not all, of the Chalk
had been removed from this central area during Lower EHocene
time; so that the Eocene deposits were laid down partly on the
Greensand and partly on the older rocks to the westward, the
flints remaining from the destruction of the Chalk being spread out
as a basement-gravel below the Bovey and Bournemouth Beds.

Here we are confronted with the difficulty created by the curious
position of the Bovey Beds. This position does not seem to be
explicable by faults. The beds have apparently been bent down
into a deep syncline by post-Eocene movements; and as the gravels
can be traced from the basin up the slopes towards the Haldon
Hills, it is evident, from the map of the Geological Survey, that they
here passed across the outcrops of the Selbornian and Permian on to
the complex of Carboniferous and Devonian rocks which borders the
granite of Dartmoor.

This transgression appears to have taken place within so short
a space, that we can only suppose that the surface which is now a
downward slope was then either a level floor or had a slight upward
slope towards the west. Thus the space between the present
termination of the Eocene gravel on Great Haldon and the similar
gravel west of Ideford is only a mile, yet in this short distance the
gravel has passed across the Greensand and the Permian, descending
through a space of about 300 feet. It is the same on the western
side of Little Haldon, where the boundary of the gravel is at about
700 feet, and the lower edge of the patch of gravel at Lindridge
(resting there upon Devonian Limestone) is at about 370 feet, the
space between being about a mile.

The gravel could not have overstepped the boundary of the
Permian on a level surface, unless the dip of the Permian rocks
was sufficient to bring in a thickness of more than 300 feet in a
mile. Now, along the southern base of Little Haldon, the base of
the Permian does fall through 250 feet in the space of a mile, so
that the dip favoured the transgression, but is not quite enough to
account for it. We must therefore assume, either that the gravel
thickened in this distance by the amount of 80 feet, or, as is more
probable, that there was a gentle upward slope where there is now
a downward slope: and if we take the difference betweef 330
and 250 feet (that is, 80 feet in a mile), the slope comes out as
Lin 66.

Assuming this to have been the average slope of the ground
between the plain of the Haldon Hills and the granite-ridge by
Elstord, north-east of Lustleigh, a distance of 53 miles, we find
that in Eocene times this ridge would have been 440 feet higher
than the level at which gravel was being spread out over the

Vol. 60. | THE VALLEY OF THE TEIGN, 325

Haidon area. We know, too, that the Bovey Beds extend as far as
Pullabrook, about a mile south of Lustleigh, and are there about
440 feet above the sea. In Kocene time, this place may have been
some 500 feet above the level of the Haldon area; and this will
account for the rapid increase in the thickness of the Bovey depasits
to the eastward, and for the great thickness that they attain at
Heathfield, where a boring traversed 520 feet without reaching
their base.

I think, therefore, that we may imagine the surface-conditions of
the Upper Eocene Epoch in Devonshire to have been as follows :—
An extensive lake or lagoon, very little above the surface of the
neighbouring sea, extending over the whole of Eastern Devonshire
and across the central parts of the county north of Dartmoor; then
steep slopes formed of Palzeozoic rocks, up to a hill-region composed
partly of such rocks and partly of the Dartmoor Granite. The sub-
sidence of Upper Eocene time seems to have carried the lacustrine
area some 600 feet or so below the level at which it stood to begin
with ; but probably deposition kept pace with depression, so that
the water was always shallow. By this subsidence the flanks of
Dartmoor were partly submerged, but the area of highland was
hardly diminished.

Kocene time closed with a general upheaval of the whole British
area, the greater part of England becoming dry land, and the
water-space being contracted to a comparatively-narrow sea lying
_ over parts of Hampshire, Dorsetshire, and the EnglishChannel. ‘his
upheaval would leave the greater part of Devonshire covered with
a mass of Kocene beds banked up against the highlands of Dartmoor
and Exmoor.

As the only Oligocene sea that we know of lay to the east of Devon-
shire, it 1s reasonable to suppose that the prevalent slope of the
western land was easterly. It is possible, indeed, that the
uplift of Oligocene time was somewhat unequal, being greater
in the west than in the east, so that a general easterly tilt was thus
early given to the Eocene beds all over England. We cannot yet
Say positively when the Bovey Basin began to be formed; but I
know of no special reason for connecting it with the early Oligocene
upheaval, and it seems much more likely to date from a later epoch.

I conclude, therefore, that we may safely assume that when the
country arose from the Eocene sea, the streams running eastward
off the watershed of Dartmoor began to excavate channels through
the Eocene deposits which flanked that area; and that these streams
were tributaries of a great river which flowed eastward into the
Oligocene sea, over a tract of land which has long since vanished
and has become part of the English Channel. It follows that the
streams which now run from north to south were then insignificant,
and were only represented by short tributaries of the eastward-
flowing rivers,

The courses of the rivers of Southern England seem to indicate
the influence of two slopes, one prevailing at one time and one at

326 MR. A. J. JUKES-BROWNE ON | Aug. 1904,

another: the one slope was easterly, and the other was southerly ;
the latter is now the dominant slope, and consequently I think that
it is of later date than the other. This brings us to consider the
question of the courses which the ancestors or precursors of the
Teign and other Dartmoor streams are likely to have taken.

We shall begin with the Upper Teign. That part of its course
which lies through the granitic area of Dartmoor was doubtless
marked out at a still earlier period, and was only being more
deeply incised during Oligocene time. In all probability, also,
the further part of its course, which is now stereotyped as the
deeply-cnt ‘gorge of the Teign,’ was initiated in Eocene time,
and at a level far above that of the existent parallel ridges. But
somewhere this high-level surface of Paleeozoic rock passed beneath
a superjacent, gently-sloping mass of Eocene deposits. So far as
my argument is concerned, it does not matter whether the mantle
of Eocene beds spread on to the granite, or whether it thinned out
at lower levels: at some point in its upper course the precursor of
the Teign left the surface of the older rocks and passed on to that
of the Eocene beds; and the general trend of this surface we believe
to have been towards the east.

We arrive therefore at the conclusion, that beyond the confines
of Dartmoor the drainage-system of Oligocene time was established
upon the surface of the Eocene beds, and consequently that this
drainage-system was afterwards transferred from the Eocene
to the Paleozoic surface. We can also see that the courses of
the rivers may have been profoundly modified in the process of
transfer, not only by their encountering rocks of varying hardness
in the Paleozoic complex, but also by the influence of powerful
earth-movements.

If, then, the Teign continued its course over Eocene beds, and if
their surface sloped eastward, it is not likely that the river at that
time followed its present anomalous course ; it is probable that it
took a much more direct line towards, and possibly across, the
valley of toe Exe. The general direction of the Upper Teign,
including the North Teign as the main tributary, is from west-
south-west to east-north-east; near Sandy Park it changes to
nearly east; while at Clifford Barton it bends to the south-east, and
passes into what may be called the Lower Teign at Dunsford.
My theory is that at this early period the valley of the Lower
Teign had no existence, but was part of the plain which sloped
gently eastward from Dartmoor across what are now the Haldon
Hills, and that there was nothing to prevent the Upper Teign
from continuing its easterly course; so that it may have joined
or received the Exe (then a much shorter stream) somewhere about
the position of Exeter.

The country to the north and south of the Teign gorge, between
Sandy Park and Clifford Barton, maintains a high level, rising to
over 1100 feet on the south side and to nearly 900 feet on the
north side: while the highest parts of the country, between Clifford

Vol. 60. | THE VALLEY OF THE TEIGN. SOL

| ‘Barton and Exeter, do not reach so much as 700 feet (see fig. 2).
Consequently, if present altitudes are any guide to the general slope
of the more ancient surface, the ancient Teign could easily have made
its way over the country which now forms the watershed between
the;Lower Teign and the Alphin Brook. This I believe to have

Fig. 2.— Map of the neighbourhood of Dunsford.

(ae ©

4
Gap WV eeke ‘Barton @
x

YK I// |
A/a] ae
yw Leigh-Cross
ARS
~

S af

f

[Scale: 1 inch=1 mile. Contours indicated in feet. The double broken lines
show the probable course of the ancient rivers. |

been its course, until certain changes took place which led to the
capture of its waters by a tributary of the river that was forming
the valley of the Teign Estuary. }

The next point that calls for explanation, is the formation of
the valley now occupied by the Estuary of the Teign. The length
of this, from near Kingsteignton to Teignmouth, is about 4 miles;
and its direction is from west to east, the land on the north side

328 MR. A. J. JUKES-BROWNE ON [Aug. 1904,

rising to over 800 feet, and that on the south side to about
500 feet. Mr. H.J. Lowe has suggested’ that this valley is that of a
stream which formerly ran from east to west and was a tributary
of the Lower Teign, which river he supposed to have then run
southward into Tor Bay; but he offers no explanation of the
manner in which the slope of such a valley could have been
reversed, and have become an outlet for the waters of what he
regards as the main stream.

In my opinion, it is much more probable that this estuary is part
of a very ancient valley, formed by a stream which ran from the
eastern part of Dartmoor over the eastward-sloping plain of
Kocene deposits in Oligocene time. The present Bovey Plain
is a locally-depressed portion of this ancient plain, and I regard
the Bovey River as a comparatively-recent development ; but there
is another stream which debouches into the Teign at Newton
Abbot, exactly opposite to the opening of the Teign estuary. ‘This
is the Lemmon, the higher tributaries of which rise on Haytor and
Bagtor Moors at a level of about 1200 feet above the sea. It is
obvious that a stream rising at so high a level, and flowing east-
ward, could take a course that was likely to have initiated the
valley of the Teign estuary, even if this valley was commenced on a
plain which was coextensive with that of Little Haldon (800 feet).

Moreover, there is some reason for believing that the Lemmon was
a more powertul stream in Oligocene and Miocene times than it is
now, and that its head-waters included those of the stream called
the Yeo, which now runs through Ashburton to join the Dart.
About 23 miles west of Newton Abbot, the Lemmon receives a small
tributary stream called the Kester Brook, which runs through a
well-marked valley, but is now a small and insignificant brook. It
seems to be merely a rivulet, fed partly by rainwater and partly by
small springs on each side of the valley as far west as Alston Cross
and Mead Farm, about a mile and a half west-north-west of Ash-
burton. But the valley continues beyond this point, and 1s fairly-
well defined by the lines for the 400-feet contour on the 6-inch and
1-inch Ordnance maps (see fig. 3, p. 329). The actual watershed at
the head of this valley appears to be about half a mile west of Mead
Farm, and only about 15 feet higher than the centre of the valley
at Mead Cross near that farm.

In the opposite direction, that is to the south-west, this col or gap
opens into the valley of a little stream which joins the Yeo in
Ashburton. On the west side of this stream is a shallow depression,
which looks like a continuation of the Kester-Brook valley ;
and this opens into the Valley of the Yeo at Cuddaford Bridge.
My suggestion is, that the valley of the Kester Brook is really
the ancient valley of the River Yeo, which in early times continued
the curve of its present course above Cuddaford Bridge, so as to
pass through the above-mentioned depression, and thence eastward
through the col at the head of the Kester-Brook valley.

' Trans. Devon. Assoc. vol. xxxv (1903) p. 645.

Vol. 60. } THE VALLEY OF THE TEIGN. 329
J

Of course, the existing depression and dry valley must belong to
the very latest stage of this ancient course of the Yeo, just previous
to its capture by a tributary of the Dart. No one could indicate
precisely the course of the stream which drained the area north of
Ashburton in Miocene and Oligocene times; but my contention is
that the drainage of this district (which is now carried into the
Dart by the Yeo) was in more ancient times directed along the line
of the Kester Brook, and helped to swell the volume of the river
which made the Teignmouth Valley. It is also noteworthy that the

Fig. 3.—Map of the neighbourhood of Ashburton.

SeoLonpmnipny
»
<4 '

‘
%

\[Bowdley

SF 3 = |
Welstor] 7 eee S Wehieae 5 evry Gis |
= 622 or

i
j

(3) :
/ Y
f ee teld
[Scale: 1 inch=1 mile. Contours indicated in feet. The double broken
lines show the probable ancient course of the Yeo. |

Hen

Yeo rises on Dartmoor at a level of about 1200 feet, and may in
ancient times have drained a larger area of the moor than it does
at present. So also may the Lemmon.

We now come to the consideration of the changes which must
have greatly modified the system of drainage, and, as I think, led
to the diversion of certain rivers from an easterly course to a
southerly one. These changes were partly regional, and partly
local.

The regional change was that which greatly augmented
the elevation of the Wealden anticline, and caused or increased the

Q. J.G.8. No. 239. Zz

330 MR. A. J. JUKES-BROWNE ON [ Aug. 1904,

general southerly inclination of Salisbury Plain, of the Dorsetshire
Downs, and of the Blackdown Hills. Judging from the elevation
of the Older Pliocene deposits in Kent, this change did not take
place till later Pliocene time.

The local change was, of course, the formation of the Bovey
syncline ; and there is nothing to tell us exactly when this was
formed, whether in Miocene times during the general elevation
of the Anglo-Gallic region, or whether it was coweval with the
uplifts of later Pliocene time. I may here point out that I do not
regard the synclinal flexure as confined to the Bovey Basin, but think
that this basin is only a local downward bulge in the course of a
much longer synclinal axis. ‘The curious plain or depression in the
granitic area around North Bovey and Moreton Hampstead, where
over a tract of about 6 square miles the average level is only
800 feet above the sea, and the communication between this and
the still lower basin near Chagford, of which mention has previously
been made (p. 319), are in a line with the Bovey Basin, and their
existence can be understood if they are regarded as due to a north-
westerly extension of the Bovey syncline.

Still farther to the north-west, between Hatherleigh and Marland,
there is a tract of clay, sand, and gravel unconnected with any
modern river-valley; and Mr. W. A. E. Ussher informs me that these
deposits bear a strong resemblance to the Bovey deposits. They
may, therefore, be of the same age; and it is a curious fact that a
prolongation of the north-western axis above indicated would
include this tract. It is also noteworthy that such a line is roughly
parallel to the watershed which runs across Devonshire, from a
point south of Hartland on the north-west to Tor Bay on the south-
east.

Returning now to the Valley of the Teign, let us consider the
effect which the general tilting and the local flexure might have
had upon the streams that we have supposed to exist in Oligocene
times. Neither change could have had much effect upon the course
of the Upper Teign flowing eastward from Dartmoor to the Exe;
but both changes would have a strong effect upon all streams which
ran from north to south, for, by increasing the fall of the ground,
they would increase the velocity and the erosive power of the
streams.

Such would be the case with the stream which I have called the
Lower Teign, and have supposed to be a tributary of the river
that flowed eastward through the Teignmouth Valley. This little
stream was doubtless carving out a valley between the Haldon Hills
and the granitic area west of Christow and Hennock throughout
Oligocene and Miocene times. The gradual sinking of the Bovey
Basin, and the increasing slope thus given to its watercourse,
would cause it to deepen the higher part of its valley, and its upper
tributaries would cut back deeply into the watershed separating it
from the valley of the Upper Teign.

If that portion of the Teign Valley which lies between Dunsford

Vol. 60. | THE VALLEY OF THE TEIGN. ae

and Clifford Bridge was originated by one of these tributaries
running off the slope of a ridge then connecting Mardon Down
with East Down, it seems quite possible that by the gradual
detrition of the country this ridge might be reduced to a low col or
pass leading from the tributary of the Lower Teign to the valley of
the Upper Teign, the latter river flowing at a considerably higher
level than the former. Under these circumstances a temporary
obstruction in the valley of the Upper Teign, such as might be
caused by a landslip, or a sudden rise of the river caused by heavy
rains, might easily send its waters over the col and into the Lower
Teign ; and whenever this happened, the new course would probably
become the permanent one, because it led down io a lower level.
Such a method of ‘ capture’ has been accepted as an explanation of
alteration in the course of the Trent and in many other cases.

If the valley of the Teign Estuary was solely the work of the
Lemmon and its tributaries, including the Bovey and the above-
mentioned Lower Teign, they would be quite equal to the task of
keeping it open, provided that the production of the Bovey syncline
was accomplished slowly, so that the rate of river-erosion could
keep pace with that of the relative vertical displacement.

As stated on p. 328, it is probable that the volume and power of
the Lemmon was materially augmented by the accession of the river
Yeo, then flowing along the line of the Kester Brook; for this
would add another head of water from the high ground of Dart-
moor. If this was so, then the diversion of the Yeo into the Valley
of the Dart is a much more recent event than the diversion of the
Upper Teign into its present course ; for, what seem to be the latest
stages of its accomplishment still remain well marked on the
geography of the country, and thus afford an illustration of the
manner in which the Lower Teign may have captured the Upper
Teign.

West of Ashburton the Yeo now passes through quite a narrow
cut between two hilis which are higher than any of the surrounding
land, one of them rising to over 500 feet; and these hills look as if
they were remnants of a ridge that once extended right across the
Ashburton Valley from north-west to south-east. It is certain, at
any rate, that if the high ground south-east of Ashburton were
united to Dartmoor by such a ridge at the present time, and if its
lowest part were not less than 400 feet above Ordnance-datum, the
River Yeo would at once be diverted into the valley of the Kester
Brook (see fig. 3, p. 329). There is, consequently, some ground for
the remark that the present features of the district harmonize very
completely with the theory that the head-waters of the Yeo have
been transferred from one valley to the other.

Let us imagine the Yeo flowing as I have supposed, and the Dart
running more or less in its present valley, and of course cutting
down to a much lower base-level than the Yeo. So long as the
general slope was easterly no change would be likely to occur, and
the Yeo would continue to deepen the valley through which it ran,
the final form of which now remains in that of the Kester Brook.

Zz 2

332 MR. A. J. JUKES-BROWNE ON [ Ang. 1904,

When, however, the easterly slope was modified and dominated by
the southerly tilt given to the country, as I suppose, in late
Pliocene time, then every eastward-flowing stream would impinge
with greater force on its southern banks and would cut deeper
curves out of the southern side of its valley; at the same time,
the erosive power of every little rivulet which flowed from north to
south would be increased. That part of the valley of the Yeo
which lies to the south of Ashburton was doubtless initiated by a
tiny tributary of the Dart; and during the gradual detrition of the
country, it would naturally encroach upon the watershed which lay
between its head and the valley beyond. This process, even without
the aid of any earth-movement, is likely to have resulted in the
trenching of the dividing ridge; and as the Yeo would be cutting
away the northern side of this ridge, it is hkely that a time would
come when it only required a flood in the valley of the Yeo to make
its waters overflow into that of the little stream to the south.

The basis of this theory, by which I have tried to explain the
peculiar course of the Teign and the origin of the Teignmouth
Valley, is the double assumption that the country had first a genera!
inclination to the eastward and was subsequently given a tilt to the
southward; but both these assumptions are in accord with geological
facts in other parts of England. They agree also with geological and
geographical facts in Devonshire: the drainage-system of Dartmoor
is likely to be older than that of the surrounding country; and the
biggest rivers of Dartmoor rise near its western border, as they
would do if the slope of the Eocene and Oligocene land was towards
the east. On the other hand, the long courses of the Tamar and
the Exe seem explicable on the supposition of a southerly slope,
which has enabled them to extend their system of drainage towards
the north. In this connection, I think that an examination of the
possible relations between the head-waters of the Exe and the Tone
might lead to interesting results.

I suspect that everywhere throughout Devonshire and Western
Somersetshire the extension of southward-flowing rivers at the
expense of eastward-flowing streams may be invoked to explain
the present somewhat-complieated system of drainage. I desire,
however, to guard myself against being understood to suggest that
either or any of these earth-movements produced a continuous regular
slopein one direction. Its quite possible that the general easterly
tilt given to the whole region in Oligocene time was interrupted
by undulations striking from north to south, and that, while the
principal or primary rivers cut across these incipient ridges, local
drainage might in some districts be directed into north-and-south
lines at an earlier date than that which I have suggested.

The series of domes and basins which now exist in the South of
England—lI mean such as the basin of Beer and Axmouth, and the
dome of the Vale of Marshwood—may have been produced by the
intersection of two series of flexures, an earlier series running from
north to south, and a later series from west to east; for we know

Vol. 60. | THE VALLEY OF THE TEIGN. 333

that in the Hampshire Basin the east-and-west axes are of post-
Oligocene date.

At the same time, I do not think that the flexures which may
have crossed the Oligocene plain were more than broad undulations;
and if the Beer Basin marks the site of one of these broad Oligocene
synclines, I think that its western limb may have been a continuous
slope up to the Dartmoor watershed. If this was the case, it is
obvious that the existence of such a shallow syncline would not
invalidate the explanation of the Valley of the Teign which has been
suggested in the preceding pages.

I have thought it desirable to limit the scope of this paper to the
Valley of the Teign and its tributaries, and to exclude the con-
sideration of other rivers; but I wish to point out the possibility
that the valley of the Teign Estuary may have been the work of the
River Dart. It is a fact that the general course of the Dart across
Dartmoor is such as to bring it to a point due west of Newton Abbot.
and consequently opposite to the entrance of the Teign Estuary. The
Dart now makes its way off Dartmoor through a deep gorge, like
that of the Upper Teign ; but when it was flowing over the high-
level surface out of which this gorge has been cut, there is no obvious
reason why it should not have continued its easterly course and have
initiated the Teignmouth Valley. In sucha case, the Lemmon would
have been merely a tributary of the Dart, and the latter would have
to be regarded as the head-source of the main Oligocene river, just
as the Dorsetshire Frome was, at a later date, the head-water of the
Solent River.’

Discussion.

The PrestpEnt said that he was glad to find that the Authors of
this and the preceding paper” were apparently inclined to refer the
principal surface-features of a county chiefly composed of ancient
rocks to the Tertiary Period.

Mr. H. B. Woopwarp remarked that papers on river-development
were most difficult to follow; they reminded him of old-fashioned
chess-problems where you had to mate in fifty or a hundred moves.
He had read the paper, but had not had time to comprehend it fully.
When he (the speaker) resided at Newton Abbot many years ago,
he thought that the Lower Teign Valley had been started by overfiow
from the lake in which the Bovey Beds were formed. Since then,
Mr. Clement Reid had seen evidence for the extension of the Eocene
strata over the Haldon Hills, now in places 800 feet above sea-
level ; and the aspect of the subject had greatly changed, owing to
the earth-movements which had to be taken into consideration.
The Author, who had asked Mr. Whitaker to act as challenger, and
read the paper, had desired him to be the defender and reply to
criticisms, and he asked permission to read a few notes from the
Author, if they were required, later on.

' See A. Strahan ‘ Geology of the Isle of Purbeck’ Mem. Geol. Sury. (1898)
p- 230.

[? C. Reid ‘ On the probable Occurrence of an Eocene Outlier off the Cornish
Coast’ Quart. Journ. Geol. Soe. vol. Ix (1904) p. 113.]

334 THE VALLEY OF THE TEIGN. [ Aug. 1904,

Dr. A. E. Savrer enquired whether the Author had studied the
various superficial deposits in the area which he described, in order
to ascertain whether their constituents were of such a character as
to favour his views. ‘These evidences of past fluviatile action often
afforded valuable corroboration to such a hypothesis as that which
had been put forward by the Author.

Mr. H. W. Moncxvon said that he had noticed a reference to the
effect of a tilt of the ground, and he ventured to remark that mere
tilting of the surface need not of necessity alter the direction of the
drainage, for as the tilting proceeded the streams would deepen
their channels—that ts, when a drainage-system was once established.
No doubt the inclination of the ground would affect the direction of
streams before a drainage-system was established.

Mr. Waurraxker said that all would agree with the previous
speaker’s remarks ; but very big and rapid earth-movements might
alter the drainage of a region. Gravel-beds might be carried off
by later erosion. There had certainly been too great a tendency to
consider the surface-features of a particular district ancient, because
the rocks which cropped out there happened to be old. He welcomed
a paper such as that under discussion, because of its suggestiveness
and its usefulness in promoting further investigation.

Mr. H. B. Woopwarp read the following extract of a letter sent
to him by the AurHor :—

‘Some one may perhaps say that the Bovey Basin may have been formed in
Oligocene time, and that the formation of this basin was enough to deflect the
river southward. My reply would be that there is absolutely no evidence
of strong earth-movements in Oligocene time, that those in the Isle of Wight
are obviously post-Oligocene, and that the Bovey syncline is comparable with
them. Further, the axis of this syncline does not run north and south, but
north-west and soutb-east, and, as I believe, it crosses the granitic area.’

Vol. 60.] | HUMAN REMAINS IN GOUGH’s CAVERN, CHEDDAR. 335

22. The Discovery of Human Rematys under the StaracMite-FLoor
of Govucu’s Cavern, CoEeppar. By Henry Naruanter Davies,
Esq., F.G.S. (Read April 13th, 1904.)

[Prats XXIX.]

Goven’s Cavern is an extensive and much-branching subterranean
waterway, which opens at the base of the cliffs on the south side of
a picturesque gorge in the Carboniferous Limestone of the Mendips,

Fig. 1—Plan of part of Gough's Cavern, Cheddar.

a

a= Entrance. b=Vestibule. g= Descending fissure, in which the

c= Limestone-block. human skeleton was found.

d=Cave-earth left in position. | l=Lowest part of the main passage.

e= Projecting rock, much rubbed 2-z2=Line of section of fig. 2, p. 336.
and polished. vr and f mark the position of dome-

f, k, k=Ascending side-fissures. shaped vents (fig. 3, p. 338).

near the village of Cheddar. For many years the proprietor,
Mr. R. C. Gough, has worked the cavern, clearing out without much

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Vol, 60.] | HUMAN REMAINS IN GOUGH’S CAVERN, CHEDDAR. 337

method the accumulation of ages, in order to make a comfortable
and easy access for visitors to the principal chambers ; and quite
recently the grandeur of the vaulting and the beautiful stalactites
in the more inaccessible parts have been revealed by the introduction
of the electric light.

In carrying out these necessary improvements, beds of stalagmite
and cave-earth, blocks of limestone, pebbles and sand have been
removed from the entrance and passages ; and the bones and teeth
of extinct and existing animals, with human relics (prehistoric and
histeric) have been brought to light, and are now to be found crowded
together in a small museum near the entrance. The objects prove
that the caves were the alternate resort of extinct animals and
man. ‘The cases contain jJawbones and teeth of the cave-hyzna,
cave-bear, cave-lion, woolly rhinoceros, boar, horse, deer, Irish
elk, etc., which have at various times been taken out of the cave-
earth during the excavations ; but they were never sound in large
numbers, while flint-flakes, knives, scrapers, borers, and chips were
plentiful, and bone and horn-borers, needles, and pins were some-
times met with. From the talus at the base of the cliffs, which
rose high enough almost to block the entrance to the cavern, a
bronze celt of the plainest type and a looped lance-head of later
date have been taken, which seems to indicate that the cavern had
become choked before the Bronze Age. I have found it quite
impossible to locate the position in the cave-earth in which any of
the above-mentioned bones and teeth were found. Some, I know,
of the cave-specimens were found in the adjoining chamber, or Old
Cave, by the father of the present proprietors; but the stock has
been considerably added to since the clearing out of the present,
or New Cave, was begun in 1892, although it is to be regretted
that no record has been kept of the dates, nature, or position in the
cave-earth of the finds.

No kuman bones had ever been found in this cavern until
December 1903, when the workmen struck a human skull and
other bones of the skeleton under circumstances that suggested their
great antiquity.

When the work of clearing out the New Cave was begun, the
entrance was only 2 feet high. Great quantities of talus and wash
had to be removed before access could be gained to the vestibule
(6, fig. 1, p. 335). Banks of mud and stone have been left in
some places, to show the original height of the floor before it was
lowered to its present level. There was no calcareous crust on the
top of the thick deposit which filled the entrance-passage. The
rock-floor was found to dip steeply inward for some yards, after
which a more gentle incline led to the point marked (/) on the plan
(fig. 1, p. 335), which is the lowest point of the central passage.
From this spot the ascent is gradual until a large chamber is entered,
when it becomes steep and sudden.

The upper stalagmite.—After the surface-accumulation
(4, fig. 2, p. 336) had been removed, the upper stalagmite (c, fig. 2)

338 MR. H. N, DAVIES ON THE DISCOVERY OF [ Aug. 1904,

was exposed. The deposit is chalky, soft, and laminated, the
average thickness of the laminae being ‘V8 mech, and that of
the whole mass from 5 to 12 inches. ‘There is a considerable
mixture of fine sand with the calcareous matter, the residue, after
treatment with strong acid, being nearly 40 per cent. of the weight
tested. Then beds of a harder and semi-crystalline porous character
are found in shallow pockets in the cave-earth in some parts of
the cavern, notably near i (fig. 1, p. 335).

Curious dome-like masses of granular and semicrystalline material,
from 6 to 18 inches in height, occur in two spots marked +
and f, fig. 1. They appear to be growths of calcareous mud,

such as may form around the
Fig. 3.—Dome-like mass of granu- mouths of springs from which
lar and semicrystalline material. waters highly charged with
i carbonate of lime were issuing.
The presence of such springs
in the cave might explain the
occurrence of the beds of
travertine - like deposit which
are found, as stated above, at
various levels in the cave-earth.
That these beds, and the upper
stalagmite-floor, are a deposit
from such slowly-flowing water,

=

Height: 6-33 inches _ dammed up for a time in the
a—Pipe; )—Calcareous layers: deeper parts of the cavern, and
c= Floor of cavern. not a drip-formation, is certain.

This latter is indeed found in
the cavern, and gives rise to some beautifully-formed stalactites and
stalagmites, but these are of a different character altogether from
the layers of chalky deposit of the upper floor and the dome-like
vents.

The cave-earth.—This is a deposit of reddish mud from 3 to
8 feet deep, containing angular masses of limestone, large and small,
which have at various times fallen from the roof; and boulders
of the same rock, well-rounded at the edges, evidently transported
by flood-waters. Bedding is distinctiy marked in some parts of the
deposit, and the thin bands of crystalline stalagmite occur in small
areas and at various depths in it. In portions of the mass, the
calcareous deposit has penetrated from tep to bottom, and the whole
thickness has been cemented into a calcareous breccia. The upper
stalagmite-bed covers the cave-earth as a continuous sheet, and the
underlying bed, to be next described, forms the floor upon which it
rests: there, being no break in the continuity of the
deposit in those parts of the cavern which have been opened out.
It thins out rapidly in fissure g, until the upper and lower beds of
stalagmite rest one upon the other at a distance of about 25 feet
from the mouth of the fissure, where the floor is cut transversely by a

Vol. 60.]. HUMAN REMAINS IN GOUGH’S CAVERN, CHEDDAR. 339

. deep rent, at the bottom of which is a backwater of the subterranean
stream that now flows out a few yards west of the entrance to
Gough’s Cavern.

Before leaving this part of the subject, two interesting stones in
the vestibule should be noted. The one marked ¢ (fig. 1, p. 335)
is a rectangular block of limestone resting horizontally upon an old
surface in the caye-earth, about 34 feet below the upper calcareous
deposit. When the earth was cleared away from it the workmen
found a large number of flint-chips embedded in the earth at its
base, and some still resting on its upper surface. The tabular block
had apparently served as a tool-bench to some cave-dwelling worker
in flint.

Near by, on the left-hand side of the entrance, to the vestibule, is
a projecting stone which has been rounded at its edges, rubbed
smooth, and polished in a striking manner. Buckland,’ referring
to stones similarly polished in the German caves of Zahnloch and
Gailenreuth, quotes the opinions of Goldfuss & Rosenmiiller, that
the rubbing and polishing are due ‘to friction from the skin and
paws’ of the animals (bears) which in remote ages frequented the
caves.

Fig. 2 (p. 336) illustrates the mass of successive deposits which
have been cleared out of the entrance and vestibule down to the level
of the line g, which marks the present floor; the darker shading
shows what still remains.

The lower bed of stalagmite.—tThis floor, upon which the
cave-earth rests (f, fig. 2), is a hard crystalline deposit. It covers
the rocky floor of the vestibule and passages in some parts, but in
others, and especially in fissure g (fig. 1, p. 335), it has some inches
of sand and pebbles beneath it.

The lateral fissure (g, fig. 1), in which the human remains were
found, may now be described. Until quite recently it remained
absolutely choked with rock-débris and earth. But as the waters
that entered the cavern from the fissures on the south side of the
cave drained backward towards the low level marked / on the
plan (fig. 1), the chambers and passages were often flooded ; and this
state of affairs causing great loss to the owner, he determined to
clear out the lateral fissure g (fig. 1), and drain off the flood-waters
into it: thus, as it afterwards appeared, imitating Nature's own
method of getting rid of them. It was while this project was
being put into execution that the discovery was made.

The sections (figs. 4 & 5, pp. 340, 341) will give an idea of the
succession and proportional thickness of the deposits that had to be
cut through. It was found that a sudden drop of a few feet occurred
at the mouth of the fissure, and this brought the accumulation to a

*Reliquiz Diluviane’ 1823, pp. 130-37.

340 MR. H. N. DAVIES ON THE DISCOVERY OF [ Aug. 1904,

depth of over 12 feet. The deposits of the main cavern passed into
this branch without break, but they took a downward inclination,

Fig. 4.—Zongitudinal section of the deposits in the lateral fissure g
(in fig. 1, p. 335),

(The bones shown are still 27 sé¢w, and x marks the position in which the
skull was found. |

a= Recent accuniulation of earth and stones: 6 inches.

= Upper bed of stalagmite: here 5 inches thick.

c=Cave-earth, with encrusted boulder (¢) and blocks of limestone and
an intermediate band of calcareous deposit (¢): 34 feet.

Ff=Lower bed of stalagmite: 6 inches.

g=Bed of sand and pebbles of Carboniferous Limestone and Old Red
Sandstone: 8 to 12 inches.

h=Carboniferous-Limestone roof and floor.

maintaining a certain parallelism with the floor and roof. A space
only just high enough to enable a man to crawl in, existed between
the upper surface of the drift and the roof at the entrance. About
12 feet within the fissure a smaller rift in the right-hand wall was

Vol. 60.] HUMAN REMAINS IN GOUGH’S CAVERN, CHEDDAR. 34]

“discovered (p, fig. 1, p. 335). It is very narrow above, but widens
to 3 feet at the lower end.

Fig. 5.—Transverse section through the lateral fissure g
(in fig. 1, p. 335.)

a = Recent accumulation of earth and stones: 6 inches.
b = Upper stalagmite-bed : 5 to 14 inches.

c = Cave-earth, containing blocks of limestone: 33 feet.
d = Lower (crystalline) stalagmite: 5 inches.

é = Bed of sand and pebbles: 8 to 12 inches.

x shows the position of the human skeleton: 1=Skull ; 2=Pelvis ;
3—=Femurs; 4=Tibia ; 5=Humerus.

The skeleton was found at the junction of these two fissures. The
surface-accumulation had been removed, the stalagmitic crust—here

342 MR. H. N. DAVIES ON THE DISCOVERY OF [Aug. 1904,

5 inches thick—had been cut through ; and a large quantity of cave-
earth and great blocks of stone from the central part of the fissure
had been cleared away in making a deep trench for the drain-piping,
when 2 feet below the under-surface of the stalagmite, the human
skull (Pl. X XIX) was brought to light. It was taken out in pieces,
but so carefully that there was no difficulty in putting it together
again. The rest of the skeleton was then unearthed ; and the bones
of an arm and a leg, some ribs, and a part of the pelvic girdle were
removed.

Fortunately, it occurred to Mr. A. G. Gough to allow the other
bones to remain in situ, so that the section (as in fig. 4, p. 340) is now
preserved for future reference. One shin-bone touched the bottom-
layer of the stalagmite and was encrusted ; the other bones were in
the earth. The skull was lying in a slightly-lower position than
the pelvis and lower extremities, at the spot marked x in fig. 4.
The legs were drawn up, one of the arms bent so as to bring the
hand to the back of the head, and the whole position of the skeleton
such as would have been assumed by the body of a drowned man
swirled into its last resting-place by a rushing torrent.

Immediately below the head is another bed of stalagmite, more
crystalline than the top-bed, and about half the thickness, but this
is not continuous. The blocks of limestone seen in fig. 4 rise out
of this; some are rounded, others angular, and one is completely
encrusted with a thin coating of granular calcareous deposit. At
the bottom of the section, and beneath a lower bed of stalagmite, is
a thick bed of sand and large well-rounded pebbles.

I have made a careful examination of the human remains. The
cranium is of medium size, the sutures intricate, the roof of excep-
tional thickness (9 millimetres). The left malar bone and the nasal
bone are missing ; there is a big hole on the same side, which has
removed a portion of the parietal and temporal bones ; the front
portion of the upper maxillary has disappeared, carrying with it the
incisors. The lower jaw is perfect, with the exception of an injured
condyle and a missing molar ; it is very wide, measuring 11°65 centi-
metres from one condyle to the other, and is powerfully formed.
The frontal is receding, though not sufficiently so to make it an
important character of the face; and as a portion of the supra-
orbital elevation is gone, it can only be said to have been con-
siderable.

It will thus be seen that the face is much mutilated; but the
cranium certainly occupies a much higher plane than the Neander-
thal or Spy specimens, approximating very nearly to the form of the
Tilbury head described and figured in Owen’s ‘ Antiquity of Man’
1884, pp. 4-9 & pls. 1-11, and now exhibited in the Natural History
Museum, South Kensington.

The measurements, as correctly as they can be made, are:—
Maximum length=185 millimetres, maximum width=130 mm.,
giving a cephalic index of about 73. The extreme thickness of the

Vol. 60.] HUMAN REMAINS IN GOUGH’S CAVERN, CHEDDAR. 343

frontal bone (9 millimetres) has been already mentioned. The
amount of prognathism cannot be determined, but from the form of
the lower jaw it must have been a marked feature of the face. The
nasal aperture is narrow, the orbits large, and the general shape of
the skuil oval. The molar teeth are worn on the right side, but
the cusps remain well-preserved on the left. The lower canines
are much worn and rounded. Two of the phalanges have found
their way into the cranium, and are now cemented to the base of
the frontal bone at the back of the orbits.

The femur measures 173 inches in maximum length, and the
humerus 123 inches; and, using Dr. Beddoe’s formule, we obtain
from either of these measurements a height of a trifle over
© feet 5 inches.

The tibia has a peculiar section, fig. 6, no. 2(p.344). The angular
portion is very acute, the sides flat, and the widest part about
three-fourths back from the ridge. Its antero-posterior diameter is
38 millimetres, and the diameter at right angles to this, drawn
from the interosseous ridge, 20 mm.; so that the latitudinal index
is 526, which is exceedingly low. With the kind permission of
the Council of the Royal College of Surgeons, and the very valuable
help of Prof. Charles Stewart, F.R.S., I have been able to obtain
sections of the Tilbury tibia, an Andamanese, and anormal English
tibia. They are shown, together with the section of the tibia from
Cheddar, in fig. 6 (p. 344); and their measurements are set forth
in the following table :—

Transverse

| aes: |
| Palin ee diameter from Latitudinal |
I: yy tnterusscous index.
diameter. :
ridge.

| _ millimetres. millimetres. |
| Cheddar cave-earth ......... 38 20° fi eee

Tilbury fluviatile deposit ... 36 21 O83
| Andaman Islands, recent ... 26 17 653
|
| Normal English ..............- 31 24 | ‘Ti4

From the foregoing measurements it will be seen that the Cheddar
tibia is an extraordinary bone, being flatter and more platyenemic
than the Tilbury specimen, which is the next most extreme type
that I have seen, and is classed in the National Collection at South
Kensington, with a query, as Palzolithic.

The flint-flakes taken from the cave-earth of the vestibule 4
and the fissure g (fig. 1, p. 335) are beautifully patinated. Some
have only a central ridge; others have two, three, or even four
ridges. Many are rounded at one end, some at both ends; others
are pointed, but not by secondary working. Two appear to hive

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Vol. 60.] HUMAN REMAINS IN GOUGH’S CAVERN, CHEDDAR. 345

been intentionally serrated, but on the whole there is an absence
of distinct traces of secondary chipping or dressing. The flakes
must, many of them, have been more than 4 inches long. If
the form and workmanship of the implements shown in fig. 7 be

Fig. 7.—Flint-blades, borers, and scrapers, found in association with
human remains in the cave-earth of Gough’s Cavern.

k
E:
2

compared with those figured by G. & A. de Mortillet in their ‘ Musée
Préhistorique* 1881, pl. xix, figs. 120, 122, & pl. xxi, figs. 135-37,
139; with some blades from Kent’s Cavern shown in the British-
Museum Collection; and with a set obtained from Bryan Cave,
Torquay, shown in the British-Museum (Natural History) Collection
(all of which are classed as Paleolithic), their striking resemblance
to all these examples will be apparent.
Q.J.G.8. No. 239. 2%

346 MR. H. N. DAVIES ON THE DISCOVERY OF [ Aug. 1904,

The animal-remains found in the cave-earth of fissure g
belonged entirely to the horse; and all the hollow bones had
been splintered for the marrow. The proprietor assures me that
the bones and teeth of extinct mammals now placed in his col-
lection were found in the cave-earth of the vestibule. These
include Ursus speleus, Hyena spelea, Felis spelea, Rhinoceros ticho-
rhinus, Cervus megaceros (?), Equus caballus, etc. As, however, i
is impossible to fix the exact position of these finds in the cave-
earth, and as they were not met with in fissure g, I feel that the
mammalian remains must not be relied upon to determine the age
of the human remains found in another part of the cavern.

The leading features of this interesting discovery may be thus
summed up :—

1. The skeleton was found embedded in the cave-earth near its
upper surface.

2..A bed of stalagmite of a chalky and laminated character
covered the cave-earth, and both the cave-earth and
covering stalagmite of the fissure are identical '
and continuous with those of other parts of the
cavern.

3. Above the stalagmite-floor, which covered the cave-earth,
a more recent accumulation of earth had been formed.

4. Beneath the skeleton another bed of stalagmite. of a harder
and semicrystalline character, was found; and underneath
this a bed of sand and well-rounded pebbles.

5. The skeleton was in a cramped position, such as would be
assumed by a drowned man.

6. The fissure is narrow, and was completely choked with the
cave-earth and its under and upper beds of stalagmite.
The latter had never been disturbed, so that interment is
out of the question.

. The bones belonged to a man about 5 feet 5 inches in height,
with an exceptionally-thick dolichocephalic skull, slightly-
prognathous jaws, and rather prominent superciliary ridges.

8, Flint-knives, scrapers, and borers are plentiful in the cave-
earth of the vestibule and of fissure g.

9. Bones and teeth of the horse only were found in the cave-
earth of the fissure; but the proprietors show teeth and
bones of extinct mammals, which they assert were taken
from the cave-earth in other parts of the cavern.

10. On comparing the form and workmanship of the flints and
the position in which they were found with those
figured by G. & A. de Mortillet in their ‘ Musée Préhistorique ’
1881, and classed by them as Solutréen and Magdalénien ;
and with specimens of undoubted Pleistocene age exhibited
in the British Museum, both at Bloomsbury and South
Kensington, as referred to previously : noting also that the
skeleton and implements were found in caye-earth under a

~J

Quart. JouRN. GEOL. Soc. Vot. LX, PL XXIX.

HUMAN SKULL FOUND IN GOUGH'S CAVERN, CHEDDAR.

Bemrose, Collo.

Vol. 60.) HUMAN REMAINS IN GOUGH’s CAVERN, CHEDDAR, 347

bed of calcareous deposit from 5 to 14 inches thick, I
conclude that the human remains are probably of late
Paleolithic age (Magdalénien of Mortillet), and that in
them we have a valuable addition to those of perhaps earlier
date found at Tilbury and Bury St. Edmunds, and the
undoubted Neolithic skeletons buried in the Perthi-Chwaren
caves or the barrows of Yorkshire and Wales.

EXPLANATION OF PLATE XXIX.

Human skull found beneath the stalagmite-floor of Gough’s Cavern.

Fig. 1. Right side. Showing the prominent supra-orbital ridge and the
receding forehead ; also the peculiar forward direction of the mastoid
processes, which would seem to indicate that the neck was short and
thick.

2. Front view. The face is much mutilated, and filled with a concrete
of cave-earth and calcareous. cement, This view shows well the
regularity of the teeth in the lower jaw, and its extreme width.

3. Left side. The thickness of the frontal bone is well shown. Parts of
the cranium are still encrusted with calcareous and earthy material.
The lower jaw has become slightly twisted in this view,

DiscussIon.

The Rev. H. H. Wixwoop, while alluding to the value of such
discoveries as that so carefully described by the Author, gave his
reasons for doubting the great antiquity of the human remains.
In the first place, evidence of the association of the bones of the
extinct animals found in the cave-earth with the skeleton was
lacking ; secondly, he enquired whether the friable bed of carbonate
of lime overlying the bones, so friable that it crumbled at the
touch, was stalagmitic in the usual accepted sense ; and thirdly,
the flint-flakes found in the earth with the remains were (in his
opinion) of a distinctly-Neolithic type, and similar to many that he
had found on the surface of the neighbouring hills.

Prof. Boyp Dawkins said that the Fellows were extremely
indebted to the Author for putting on record the facts of this
interesting discovery. But it involved no more evidence of the
precise antiquity of the deposits than that brought forward from
many other caverns. Indeed, it was impossible to explore any
series of caverns in any part of this country without finding human
remains. Stalagmite was of practically no value as evidence for
age. In 1877 he (the speaker) examined the stalagmite of
Ingleborough Cave, previously examined by Prof. Phillips in 1845,
and he was able to determine the rate of accumulation of stalagmite
as being three-tenths of an inch per annum. It was true that
the flint-flakes exhibited appeared to be Neolithic, but such
implements were in use as late as the Bronze Age. The tibia
shown by the Author was, after all, but slightly platyenemic, and
platycnemism had no relation to race; it implied merely the free
use of the foot, confined at most in moccasins. The great majority
of Neolithic skeletons possessed a platycnemic tibia. Nor was the

Za Z

348 HUMAN REMAINS IN GOUGH’S CAVERN, CHEDDAR. | Aug. 1904,
’ He 5

skull older in type than Neolithic, and the stature inferred by
the Author was very near the normal stature of the Neolithic
Iberic population of this country. Statements in regard to the
antiquity of man must always be scrutinized with the narrowest
possible criticism.

Mr. W. Date said that, as a collector of flint-implements for
many years, he naturally gravitated towards those on the table as
soon as he entered the room, and at once made up his mind that
they belonged to the Neolithic Age, and late in that period. Indeed
some of the long and skilfully-struck flakes were exactly similar to
those often found associated with relics of the Bronze Age.

‘The: AurHor thanked the speakers’ for their criticism ofvhis paper.
In reply to Mr. Winwood, he referred to the mass ‘of ‘calcareous
deposit of travertine-like nature, which ‘lay ‘on the table, and which
the Author had himself suggested to have been more rapidly;formed
than the lower true stalagmite.: The’ flints might. be» Neolithic
in appearance, although they were certainly not surface- flints, but
found in the cave- earth, of whatever age that might be. Reply’ ing
to Prof. Boyd Dawkins, the ‘Author agreed that. platy cnemism was
not a characteristic of race, and that well-struck flints might be of
late Neolithic Age; but, referring again to their presence in the
cave-earth under. a stalagmitic floor, ad to their close resemblance
to the’ blades and borers found under the same conditions ‘and
classed by Mortillet and others as Magdalénien, he thought that his
suggestion of a late Paleolithic or very: early Neolithic date for
these flints was more agreeable’to the facts ;and,.if that were so,
the human remains found with them must be of the sameage.

Vol. 60.] | NON-SEQUENCE BETWEEN KEUPER AND RHXTIC. 349

23. The Evipence for a Non-Sequence between the Kuvprr and
Ruztic Serres ix Norru-West GLovucestERSHIRE and WoRcEs-
TERSHIRE. By Linspatt Ricwarpson, Esq., F.G.8S. (Read
June 8th, 1904.)

[Mar on p. 350. ]

Duvriné my investigations of the Rhetic Series in Worcestershire
and North-West Gloucestershire, the results of which are in part
chronicled in the ‘ Proceedings of the Cotteswold Naturalists’ Field-
Club’? and in the ‘ Geological Magazine, * two facts were most
noticeable. The first was that above a particular bed in the Rheetic
Series the remaining component deposits were remarkably per-
sistent ; while the second was that below that stratigraphical
horizon such persistency was not found. The stratigraphical horizon
referred to is that of the well-known Bone-Bed of the sections at
Aust and Garden Cliffs, and of the less-known Bone-Beds at Wainlode
and Sedbury.

The stratigraphical details may be dealt with first. In most of
the sections in Worcestershire a massive bed of sandstone is the
equivalent of the thin pyritic Bone-Bed which is so crowded with
vertebrate-remains at Garden Cliff, and the contemporaneity of
these deposits might be at first doubted. Wainlode Cliff, however,
furnishes the clue to the whole question, for in that cliff-section
may be observed the change from a thin pyritic stratum (only
an inch or so thick) to a micaceous sandstone-bed, usually
devoid of vertebrate-remains, and about a foot thick. The latter
development, however, contains in some abundance those equivocal
easts to which the name of Pullastra arenicola has been so trequently
applied; and also a broad form of what appears to be Modiola
minima—but only as obscure casts. The point, however, to which
attention is particularly directed is the gradual transition between
the two varieties of the Bone-Bed. Below, and separating the
Bone-Bed from the ‘Tea-Green Marls’ of the Upper Keuper, is
a deposit of Black Shale 2 feet thick. The line of junction of
the shale with the Keuper Marl may be described as sharply
defined, and only very rarely is there an extremely-thin deposit of
arenaceous matter intervening between the two formations. At
Norton, about 14 miies to the south-east by east of Wainlode, there
is a section in a lane-cutting 300 yards north-east of the church,
in which the Bone-Bed is seen as a stratum 15 inches thick,
with a few fish-remains and an occasional small quartz-pebble.
Black Shales, with a thickness of 16 inches, separate this bed
from the ‘Tea-Green Marls’: the line of demarcation between
the two being again sharply defined.

* Vol. xiv (1903) pp. 127-74, 251-56.
* Geol. Mag. 1903, pp. 80-82.

| A

Droitwich
Map |
to show the relationship f=
of the anticlinal & synclinal flexures {D unhampstead

noticed in this paper, to those —See—
of which there is evidence in the SC
Inferior-Oolite Series. : =

Worcester

+ > = : =
Croome D’Abitot:

R)

Bourne Bank

Q Upton-on-Severn

Pes Feath Hill

Berrow Hi!! oy =

R

Tewkesbury ————— ——

= == =

Coomb Hill- —

$ Lassington—— —Cheltenham-

Gloucester—

Vol. 60.] | NON-SEQUENCE BETWEEN KEUPER AND RH2XTIC. Bal

At Coomb Hill, near Cheltenham, the Bone-Bed is difficult to
find, but I have succeeded in discovering a typical development.
From the writings of H. E. Strickland also, it is known that the
lithic and faunal characters of the stratum here are similar to those
which may be noted at that end of Wainlode Cliff which is farthest
from the Red Lion Hotel; for, to quote that author, it

‘rarely exceeds an inch in thickness, and frequently thins out in short
distances to one-fourth of an inch or less. It consists chiefly of a dense mass
of scales, teeth, bones and sinall coprolites, cemented by pyrites, the golden
colour of which contrasts beautifully with the jet-black of the animal-remains.’*

The fragments, Strickland noticed, ‘have evidently been subjected
to a gentle mechanical action,’ as they often present ‘broken and
worn surfaces.’

In the shallow cutting through which the Tewkesbury-and-
Ledbury road passes at Sarn Hill, near Bushley, the Bone-Bed-
equivalent is a massive stratum of yellowish micaceous sandstone,
14 inches thick, and is separated by 2 feet 8 inches of Black
Shale from the ‘Tea-Green Marls,’ with a sharply-defined line
of junction.

At Bourne Bank, near Defford (Worcestershire), the Bone-Bed-
equivalent resembles that at Bushley, but is here 2 feet thick,
and is devoid of vertebrate-remains. In a ‘ Postscript to the
Memoir on the Occurrence of the “‘ Bristol Bone-Bed ” in the Neigh-
bourhood of Tewkesbury,’ Strickland brought forward evidence to
show that an ossiferous development of this Bone-Bed-equivalent
was passed through by a shaft sunk on Defford Common, about
half-a-mile to the east of the escarpment.* Pieces of this bed
brought to the surface yielded to Strickland his ‘ Pullastra
arenicola, and teeth, scales, and coprolites of fishes. The actual
junction of the Keuper and Rhetic Series cannot be seen at Bourne
Bank; but, in a road-cutting about 2% miles to the north, the
deposit intervening between the Bone-Bed-equivalent and the
Keuper Marls is seen to be 2 feet 10 inches thick. The Bone-Bed-
equivalent here is similar to that at Bourne Bank, and is exposed
for a thickness of 13 inches, but that is not its total thickness; the
section then becomes obscured, and the details are doubtful.

The most important section now open in Worcestershire is at
Crowle. Here, instead of the sequence, ‘Tea-Green Marls,’ Black
Shale, Bone-Bed-equivalent, we have, in ascending order, ‘ Tea-
Green Marls,’ Sandstone (with a little shaly matter intercalated
near the base), shales, and Bone-Bed-equivalent. The deposit of
sandstone above the ‘ Tea-Green Marls’ is therefore an addi-
tional deposit, and has come in between this locality and the
section near Croome D’Abitot. Indeed, it has come in between the
farm called Muckenhill and Croome D’Abitot, for in the farm-
yard it is seen resting upon the ‘Tea-Green Marls,’ and similar
phenomena are to be observed at Churchill Wood, near Spetchley.

? [Sir W. Jardine] ‘ Memoirs of H. E. Strickland ’ 1858. p. 155.
* Ihid. p. 160.

302 MR. RICHARDSON ON NON-SEQUENCE BELWEEN [ Aug. 1904,

It may be as well to mention here that had the term ‘ Bone-Bed’
been applied to any bed yielding vertebrate-remains, then in the
Crowle section the series of sandstone-layers alternating with
shale, and 20 inches above the Bone-Bed-equivalent, would have
had to have been thus denominated. But the deposit (Bed 15)
is frequently seen to be of ‘Bone-Bed’ nature, especially at
Denny Hill, near Gloucester, and in places in the Garden-Cliff
section.

The section in the railway-cutting at Dunhampstead shows
the same sequence of deposits as the Crowle exposure, together
with higher beds; but from the account of this section given
by Mr. W. J. Harrison, F.G.S., and my own observations, there
seems to be little doubt that the Rhetic rocks are thicker
here than at any other locality in Worcestershire; this
is certainly the case with the beds that are visible. The Bone-
Bed-equivalent at Dunhampstead is a massive bed, with a maximum
thickness of 30 inches.

About 7 miles across country, in a south-easterly direction, is an
exposure at Abbots (Hob) Lench, where it is important to note
that, instead of a sandstone-bed resting upon the ‘ Tea-Green Marls,’
the Bone-Bed-equivalent itself (14 inches thick) is seen to be
separated by a deposit of shale, only about 28 inches thick, from
the Keuper Marls. This means that the sandstone-bed, which at
Dunhampstead was seen resting directly upon the Keuper Marls,
is absent here. As I have elsewhere stated,’ this Bone-Bed-equi-
valent partakes of the nature of a true Bone-Bed in this village ;
for, from a well sunk here, were obtained pieces of typical pyritic
rock charged with fish-scales and some other vertebrate-remains.

At Marl Chiff, on the borders of Worcestershire and Warwick-
shire, a thin layer of sandstone (with a few fish-scales, and but
an inch thick) is the Bone-Bed-equivalent, and is separated from
the ‘ Tea-Green Marls’ by 2 feet of Black Shale ; a state of affairs
somewhat similar to that noted at one part of Wainlode Cliff.

Concerning the Bone-Bed of Worcestershire, Strickland wrote :

‘It appears, however, that this stratum, which in East Devon, Somerset, and
Gloucestershire is so highly charged with organic remains, loses its ossiferous
character when we enter Worcestershire. Its identity, however, is not lost ;
and when it is considered that from Axmouth on the south to Dunhamstead
on the north is a distance of about 112 miles, we have a remarkable instance of
the continuity of a very thin stratum over a great distance.’ *

Proceeding now from Wainlode Cliff in a more or less south-
westerly direction, the first section to be noted is in the railway-
cutting at Lassington. This section is now so much overgrown that
very little, and nothing definite, can be made out. W. C. Lucy’
stated that the ‘ Bone-Bed’ and ‘ paper-shales’ of Westbury are
absent, while the Rheetic Beds are represented by a band of
stone 6 inches thick, in which Pseudomonotis decussata occurs.

' Geol. Mag. 1903, p. 81.
* ‘Memoirs of H. E. Strickland’ 1858, p. 157.
3 Proc. Cotteswold Nat. F.-C. vol. viii (1886) pp. 216, 225.

Vol. 60.}. THE KEUPER AND RHZETIC IN GLOUCESTERSHIRE, ETC. ddd

- These details he observed when the cutting was in the course of
excavation. Mr. H. B. Woodward,’ however, states that ‘ dark
shaly marls,’ belonging to the Rhetic, are faulted against the
Keuper. The phenomena noted by Lucy, and explained by that
author as being due to the absence of certain deposits, may, of
course, be the result of a fault with some overthrust. I refrain
from mentioning the section further, than to express the hope that
if any sections of these beds are opened the fact will be at once
made known.

At Denny Hill, distant from Lassington a little over 4 miles, the
Bone-Bed is seen resting directly upon the ‘Tea-Green Marls.’
This section has been recently described in the ‘ Proceedings of the
Cotteswold Naturalists’ Field-Club’,? and from that record it will
be noticed that the several deposits there visible above the Bone-
Bed agree closely with the equivalent beds at Garden Cliff. The
absence of the well-known ‘ Pullastra-Sandstones’ of Garden Cliff
is at once apparent; and, since at Denny Hill the Bone-Bed rests
directly upon the marls of the Keuper Series, it follows that 6 feet
5 inches* of Rhetic deposit—as seen below the Bone-Bed at
Garden Cliff—are absent here, and this thickness is, of course,
considerable when it is remembered that the true English Rheetic
seldom exceeds 35 feet in thickness.

At Chaxhill, about 2 miles south-west by west of Denny Hill,
the ‘Pullastra-Sandstones ’’ are present; the total thickness of the
deposit below the Bone-Bed and above the Keuper Marls is 7 feet
2 inches*; a slight increase really upon the Garden-Cliff section,
because of the more equal thickness of the several beds.

As the late Robert Etheridge, F.R.S., has written, it is probable
that
‘this chief Bone-Bed [No. 15 in my sections] was synchronously deposited over
the area it now occupies in the West and South-West of England.’ °
This ‘ chief Bone-Bed ’ is seen at Sedbury Cliff on the Severn, near
Chepstow, resting upon the ‘ Tea-Green Marls,’ with included rolled
fragments of that rock. The Aust and Sedbury sections, however,
are outside the district under consideration, and, moreover, it is
probable that a barrier of Palaeozoic rocks intervened between them
and the Garden-Cliff section. That such a barrier, more or less
continuous, must have existed in early Rhetic times is shown by
the Rhetic Beds resting upon the Carboniferous Limestone in
Tortworth Park,® and evidence of land in the same epoch is to be
had in the railway-cutting at Lilliput, near Yate. If, then, as
seems most probable, a Paleozoic barrier separated the Aust gulf
from the stretch of water about Garden Cliff, it may supply an
answer in the affirmative to Etheridge’s statement that the strata

* Mem. Geol. Sury.: ‘The Jurassic Rocks of Britain’ vol. iii (1893) ‘The
Lias’” p. 141. ’

2 Vol. xiv (1903) p. 254.

3 Maximum, 7 feet 9 inches. * Maximum, 7 feet 8 inches.

> Proc. Cotteswold Nat.-F.-C. vol. iii (1865) p. 224.

® Tbid. p. 234. ie ck ;

do4 MR. RICHARDSON ON NON-SEQUENCE BETWEEN [ Aug. 1904,

now exposed in the sections at Aust and Westbury ‘must have
been deposited in a different area, and open to another sea or
estuary.’ !

In the foregoing record of certain stratigraphical details, frequent
reference has been made to the Bone-Bed or Bone-Bed-equi-
valent. That term has been employed for the want of a better.
By the use of this denomination I do not imply that the stratum is
necessarily crowded with vertebrate-remains : it happens to be so at
Garden and Wainlode Cliffs and Coomb Hill in the district under
review ; hence the reason why it has been made use of to indicate
the equivalent deposit in other localities, even if that equivalent
does not contain vertebrate-remains. J am inclined to think that
this Bone-Bed (15) was accumulated slowly. At Aust and Sedbury
Cliffs it is conglomeratic, and might at first sight appear to have
been formed somewhat rapidly, but the deposit at these localities
is a littoral accumulation. In the Black Shales which were laid
down during the contorta-age, fish-remains as a rule are not
abundant ; and I am inclined to agree with Strickland’s idea that

‘this great continuity of extent [of the Bone-Bed], combined with the pro-
digious abundance of organic remains in some parts of this stratum, render it
probable that a much longer period may have elapsed during its deposit than
in the case of an equal thickness of the less fossiliferous clay-beds above and
HelOW.u. Ste ie Generations of fishes and saurians may have added their remains
to the common mass, while from the clearness of the water, or from the
existence of a gentle current which prevented the deposit of muddy particles,
scarcely any mineral matter was added to the bottom of the sea.’ ”

Now, as a rule, the fish-remains in the Bone-Bed at Wainlode Cliff
occur in regular layers, and are very evenly distributed: the rock
being fissile, and in all respects resembling a deposit which was
formed slowly. But the bed, which is about an inch thick at one
end of Wainlode Cliff, took the same time in its formation as the
30 inches of sandstone at Dunhampstead.

Accumulations of vertebrate-remains or ‘ Bone-Beds’ occur at
different horizons in the Lower Rhetic Stage; for example, the
‘ Bone-Bed’ at Crowle, near Worcester, is Bed 13; at Wainlode
Cliff and Coomb Hill, Bed 15; at Denny Hill, Bed 13; while at
Garden Cliff there are at least four deserving of the name. More-
over, the Pecten-Beds (7 & 55) are often full of vertebrate-remains,
so much so that the bed distinguished in my record as 56 at
Wainlode Cliff was noticed by Strickland as ‘a second ossiferous '
bed.’ The stratum which has been distinguished as 15 in com-
munications made to the Cotteswold Naturalists’ Field-Club, and
that dealing with Sedbury Cliff to this Society, may at first sight
appear to occupy different horizons, but this is only if the several
sections be studied from the base upward.

There is always some difficulty in correlating the various sections,
because of the want of fossils known from investigations over large
1 Trans. Cardiff Nat. Soc. vol. iii (1870-71) pt. ii, p. 47.

>

> «Memoirs of H. E. Strickland’ 1858, pp. 157, 158.

Vol. 60.] THE KEUPER AND RHA&TIC IN GLOUCESTERSHIRE, ETC. 355

_ tracts of country to characterize definite horizons ; but the Estheria-

and Pecten-Beds are fairly persistent; and it is best in correlating
the sections to find these horizons first, and with their aid it will
be seen that down to Bed 15 the sections admit of satisfactory
correlation. In some sections the Bone-Bed does not occur at all,
possibly because the surface of the Keuper Marls, or the rock
composing the land-surface at the time of its formation, was not
sufficiently submerged.

Down to Bed 15, then, the various sections can be correlated
almost bed for bed, and the contemporaneity of deposits which
admit of such exact correlation seems most probable. But below
Bed 15 we have in one locality no Rhetic deposit, in another as
much as between 7 and 8 feet.

The writings of our foremost geologists on questions of historical
geology show that the Keuper ‘Epoch closed with a scene of arid
wastes and an inland sea reduced to slowly-shrinking lakes ; lakes
with surrounding land which, I think, was once formed under the
waters of the more extensive Keuper sea. Then, as Mr. A. J.
Jukes-Browne has written,

‘the epoch of the Avicula-contorta zone marks the time when the depression had
proceeded so far as to submerge the lowest tract of land which lay between the
great salt-lakes and the widespreading southern ocean.’?

Now, may not the same forces which caused the depression in the
south-east have affected the Keuper rocks and thrown them into
slight anticlinal and synclinal flexures? A few lakes would still
remain, but with their outlines somewhat modified by these earth-
movements.

Mr. 8. 8. Buckman, F.G.S., has indicated the axes of certain
anticlines and synclines in the Inferior-Oolite Beds of the Mid-
and North Cotteswolds among other regions. Such flexuring caused
the Bajocian Denudation, and there is moreover evidence to show
that flexuring along practically the same lines of weakness took place
about the middle of the Harpoceratan Age or in early Ludwigian
times (post-Lilli, pre-scissi). Also earth-pressures were at work
during the hemera concavi. It seems reasonable to suppose that
the Liassic rocks might have been similarly affected long before the
epoch in which the Inferior-Oolite Beds were laid down: indeed,
Mr. Buckman has remarked that the Lias in the Dundry area ‘ was
laid down on a constantly-moving surface.’ *

Certain of the anticlinal and synclinal axes noticed by Mr. Buck-
man in his description of the causes and effects of the Bajocian
Denudation may be now mentioned. The most important anticline
is along the Moreton Valley, and if the line of elevation be produced
in a northerly direction it will be found to coincide with the Pennine
axis. A synclinal.axis is noticeable at Cleeve Hill; an anticline
at Birdlip; and a syncline again between Stroud and Painswick.

* «The Building of the British Isles’ 2nd ed. (1892) p. 222.
* Proc. Geol. Assoc. voi. xvii (1902) p. 153.

396

MR. RICHARDSON ON NON-SEQUENCE BETWEEN

[Aug.1904,

Church Lawford—where the Rhvetic Black Shales, according to

.—NSection showing the relationship of the Rhetic deposits below the Bone-Bed to the Keuper Marts.

)

12.

F

S.E.by E.

N.N.E.: N.W.by W,

S.S.W.(approximate)

JID FPIN-----

yous] s3oqqy----

yueg ouimog----

JID epoyure p----

ao
o oo
uoyVIng x
he
% O
is]
~
>A
‘ %
Whats
l \
1 N
l \
lin be aay
! re
Il 3
i —
i—
I!
HES
tm
Ley)
o
x

BND so

-

-

Paleozoic Rocks

sa

ee a) ee aR

Horizontal Scale, 1 inch

-

10 miles (about).

Mr. H. B. Woodward, are absent
—is situated near the Moreton-
Pennine anticline ; Dunhamp-
stead ana Crowle—where the

- greatest thickness of the Rheetic

4 feet.

Vertical Scale, % inch

Series obtains in Worcestershire
—are situated on a continuation
of the Cleeve-Hill synclinal axis
(see map, fig. 1, p. 350); and
the Birdlip anticlinal axis makes
in the direction of Lassington.
This is remarkable, but, as
already stated, it is not desirable
that the Lassington section be
discussed forthe present purpose:
the Denny- Hill section, however, ©
shows for certain that there is
an anticline in this neighbour-
hood. Again, between Pains-
wick and Stroud a synclinal
flexure is noticeable in the
Inferior-Oolite rocks, and, what
is more, it will be observed that
it follows somewhat closely upon
the Birdlip anticline. Such is
the case in the Rhetic also
at Denny Hill there is evidence
of the proximity of an anticline,
while at Chaxhill—but 24 miles
distant—there is very striking
evidence of a syncline.

To sum up, then, it will be
noticed that — confining our
attention to the rocks of
North-West Gloucestershire and
Worcestershire — there is evi-
dence to suggest that there were
earth-pressures at work at the
close of the Keuper Epoch, which
caused the deposits to be thrown
into shght synclinal and anti-
clinal flexures. In the depressed
areas the earlier deposits of the
Rhetic were laid down, and
successive overlap on to the marls
seems to have taken place (fig. 2).

Unfortunately, the products of

the Rheetic Beds that are of economic importance are not numerous:

Vol. 60.}] THE KBUPER AND RHZTIC IN GLOUCESTERSHIRE, ETC. 397

consequently, sections by quarrying and mining are few in number:
river-cliffs, railway- and lane-cuttings afford the best exposures.
If there were anything like half the number of sections that are
obtainable in the Inferior Oolite of the Cheltenham district, this
theory, I venture to think, would have had more facts to support
it. At one time I was inclined to believe that—allowing, of
course, for unequal deposition—the several beds of the Rhetic
Series seen below the Bone-Bed had been deposited over the greater
part of England; but that subsequent to their deposition they had
been thrown into slight synclines and anticlines, and that after
the anticlines had suffered erosion the Bone-Bed was deposited non-
sequentially over the whole. This view I now consider improbable.

In my opinion, the evidence obtainable suggests that it was the
Keuper_deposits which were thus affected ; and_in immediate pre-

Rheetic times. According to. my theory, when the Rhetic ocean
gained ¢ecéss ‘to’ the British area~it-spredd over an undulating ex-
panse of Keuper Marls. In some areas, however, it has been stated,
lakes probably existed, and it would be in these areas that the
complete sequence from the Keuper to Rheetic deposits should be
looked for. The section of depositsformed under the conditions stated
would be essentially of transitional nature, as at Watchet ; but where
the Rhetic ocean spread over the surrounding ground a non-sequence
would result. Thus, at the present time, the junction-line would
appear sharply defined; there would be no transitional signs, and
practically no erosion. As the area sank gradually the Rheetic ocean
slowly encroached upon the land-surface, and successive overlaps and
oversteps resulted. The lower deposits of the Rheetic Series now ex-
posed at Garden Cliff and Chaxhill appear to have been laid down in
a relatively much-depressed area between the Paleozoic barrier and
the anticline, somewhere in the Denny-Hill and Lassington district.
If sufficient sections had been obtainable between Chaxhill and
Denny Hill, this successive overlap should have been observable.

It seems probable that it was during the formation of the Bone-
Bed that the greatest overlap took place. In the sections at New
Clifton (Bristol), and again in the railway-cutting at Lilliput, the
Bone-Bed is seen to encroach considerably upon what was, at one
time in the Rheetic Epoch, land composed of Paleozoic rocks. The
‘Tea-Green Marls’ of Sedbury Cliff do not appear to have been
submerged until the time when the Bone-Bed was formed; and
such would appear to be the case with many sections in the Bristol
district also. The Keuper Marls of Gold Cliff, near Newport, may
have been submerged about this time, for into their fissured surface
J. E. Lee noted that Bone-Bed material had been washed.' A
certain amount of littoral action is shown by the formation of a
conglomerate such as that at Aust and Sedbury Cliffs. At Denny
Hill the Bone-Bed contains small pieces of derived marl.

There is one other point to which I would direct attention. At

1 Rep. Brit. Assoc. (Brighton, 1872) Trans. Sections, p. 116; and ‘ Note-book
of an Amateur Geologist ’ 1881, p. 72 & pls. elxxi-elxxii.

358 NON-SEQUENCE BETWEEN KEUPER AND RH TIC. [ Aug. 1904,

those localities where the distribution of the infra-Bone-Bed
deposits indicates elevation of the Keuper Marls in immediate pre-
Rheetic times, it is noticeable that there is a non-sequence at the
base of the Lias, At Sedbury Cliff, a locality where the Keuper
Marls were not wholly submerged until Bone-Bed times, a bed of
conglomerate separates the basal Liassic deposits from the Rhetic ;
at Lassington there is a remanié-bed ; and in Warwickshire—in a
region affected by the movements along the Pennine-Moreton anti-
clinal axis—the ‘ Guinea-Bed’ points to a non-sequence. Indeed,
to quote Mr. H. B. Woodward, near Church Lawford

‘Tt is not improbable ... . that there was some irregular overlap of the
Rhetic Beds, accompanied by reconstruction of some layers, during the
changing conditions that ushered in the Lower Lias.’

1 Mem. Geol, Surv. ‘The Jurassic Rocks of Britain, vol. iii (1893) The
Lias’ p. 15).

Vol. 60. ] PLESIOSAURUS FROM WESTBURY-ON-SEVERN. 359

24. On a sMALL PLESIOSAURUS-SKELETON from the WuHitTE Liss of
WESTBURY-ON-SEVERN. By Winrour FRepDprick GWINNELL,

Esq., F.G.S. (Read June 8th, 1904.)
[ Abstract. |

THE remains described were found on the Severn beach at Easter
1904, and had evidently fallen recently from the cliff above, which
is there made up of the Upper Rheetic Beds, including the Lstheria-
Bed and the White Lias Limestone. The matrix of the specimen
corresponds with the White Lias in colour, texture, and material,
and it is similarly traversed by fissures often coated with dendrites.
The remains are in excellent preservation, ueither pyritized nor
appreciably carbonized, as is so usual in ‘ Bone-Bed’ specimens.
They include more than twenty small dorsal vertebra, with spinous
and transverse processes, lying in natural sequence. Pseudomorphs
in calcite of the spinal cord and intervertebral cartilages occur also
in relative position. Several slender ribs, and indications of other
bones (probably from the pectoral or pelvic arches), also occur in the
slab, but are not yet worked out. Hitherto only single vertebre
or fragmentary bones of Plestosaurus have been recorded from the
Rheetics in Britain, and these only from the bone-beds below the
White Lias. At present, it has not been found possible to assign
the fossil to any existing species, but the characters most nearly
approach those of Plestosaurus bibractensis.

The specimen has been presented to, and accepted by, the British
Museum (Natural History).

360 MR. W. G. FEARNSIDES ON UPPER GAULT [Aug. 1904,

25. On the OccuRRENCE of a Limestone with Upper Gavtt Fossits
at BARNWELL, neav CamBripee. By WitiiaAm Grorcr Frarn-
sipEs, Esq., M.A., F.G.S. (Read May 25th, 1904.)

In the course of a recent examination of the great Gault-pit worked
by the Cambridge Brick Company, Ltd., at Barnwell, my atten-
tion was drawn to an unusual and inconstant hard bed which is
occasionally met with in the lowest part of the pit.

On examination, the hard material was found to consist largely
of comminuted Jnoceramus-fragments, with occasional ammonites
and other shells, and a careful search in this and the adjoining
clay proved them to be quite fossiliferous. Unfortunately, the
specimens obtained are only fragmentary, but as they seem to
indicate a horizon higher than any yet recorded from the Cam-
bridgeshire Gault,’ they may perhaps be worthy of record.

The section now seen is as follows, in descending order :—

Thickness
in feet.

(1) Surface-soil, with gravel and Chalk-Marl, disturbed in the former } 1hiode
working of the Cambridge Greensand. ° ;

(2) Dull leaden-grey clay, which on drying becomes more creamy \
and very pale. This is generally almost devoid of determin- |
able fossils except Plicatula, but contains a few scattered } 39
phosphate-nodules, marcasite-concretions, and pieces of car- |
bonized wood. y
(3) Compact, well-jointed, homogeneous clay of a distinct ig
colour, containing large but undeterminable ammonites of
the rostratus- or Bouchardianus-type; also occasional sharks’ {
teeth and lamellibranch-shells. |
(4) The Hard Band, with numerous specimens of Jnoceraimus,
Schlenbachia varicosa, Terebratula biplicata, sharks’ teeth, + Oto 1
and many phosphate-nodules.
(5) Very blue, well-laminated clay, with abundant fragments et ee
fossils and many pale phosphate-nodules.

oo

Of these, the three lowest divisions are the most interesting, and
nearly all the fossils come from the beds (4) and (5). The Hard
Band (4) is extremely variable in thickness. It occurs in a series of
flattened lenticles, generally a few yards in diameter and up toa
foot in thickness. It is largely made up of broken shells and
phosphate-nodules, with a few bone-fragments and extraneous
pebbles of mud, and is harsh to the touch. Some of the ammonites
and Inocerami are very large, and specimens of the latter 3, 4, and
even 5 inches across are not uncommon.

Petrologically, the Hard Band is best described as a somewhat
muddy shell-limestone. It contains abundant phosphate-nodules,

1 See Mem. Geol. Surv. ‘The Cretaceous Rocks of Britain, vol. i (1900)
The Gault & Upper Greensand of England’ p. 287.

Vol. 60. j LIMESTONE AT BARNWELL, 361

of which at least three types occur: these we may distinguish as
the green, the pale, and the dark-brown.

The green nodules are more or less irregular, subcylindrical
lumps of phosphatized mud. They enclose no obvious shell-frag-
ments, and never contain more than about 10 per cent. of calctum-
phosphate. They seem to represent mud-pebbles deposited among
the shells, and have probably become phosphatized in situ.

The pale nodules (which are sometimes yellow, sometimes
brown) are yery similar in structure to the green, but contain a
much greater proportion of calcium-phosphate, generally about 35 to
40 percent. ‘They are very irregular in shape, but are never obviously
rolled. A few seem to be the internal casts of shells now destroyed.

The dark-brown nodules are less common; they differ from
the others in that they have well-rounded shapes, and appear to have
been derived from older beds. They are much richer in phosphates
than any of the others, analysis showing something more than
50 per cent. of calcium-phosphate. ‘They are often bordered with
material like that of the pale nodules, and contain no determinable
fossils.

Under the microscope, the rock * is seen to be made up of more or
less recognizable shell-fragments. About one-half of it consists of
the fibrous calcite-prisms characteristic of Jnoceramus. Forami-
nifera are also very abundant, and many forms occur. Globigerina,
Miliola, Nodosaria, and Textilaria are the most prominent genera.
As usual, they have the chambers filled with calcite, which is in
erystalline continuity with the test, and so shows the usual black
cross exceedingly well. Characteristic fragments of various other
lamellibranchs, brachiopods, small gasteropods, echinoids, and
crustacea are recognizable, but form only a small proportion of the
whole. <A few of the fragments have become granular, but such as
were originally calcite have retained even the most minute of their
microstructures. Of other constituents a fibrous, yellowish-brown,
non-pleochroic mineral giving low-interference colours and straight
extinction, and occurring in shreds and plates, is the most abundant.
Some of it appears to show organic structure, and may, I think, be
chitin. Chips of clastic quartz occur sporadically, and one or two
prisms of fairly fresh orthoclase were observed. A few small and
irregular masses of isotropic or aggregate-polarizing glauconite were
also seen in the siice examined, and are probably much more abundant
in other parts of the rock. A groundmass is present, in small and
variable quantity. Much of it is calcite, and is in crystalline con-
tinuity with the adjoining shell-fragments, but a certain amount of
finely-granular material and irresolvable clay-paste occurs in the
interstices. Unfortunately, the slice does not happen to show any
of the phosphate-nodules.

The fauna contained in the Hard Band is not markedly different
from that of the immediately-underlying clay, and in the following

* Slide No. 4808 in the Sedgwick-Museum Collection, Cambridge.
Q.J.G.8. No. 239. 2B

362 MR. W, G. FEARNSIDES ON UPPER GAULT

[ Aug. 1904,

list no attempt has been made to separate the two. The fauna
that I have obtained is as follows :—

ForAMINIFERA.
Globigerina.
Miliola.
Nodosaria.
Textilaria.
ACTINOZOA.

Trochocyathus angulatus, Dune.

ECuINnoDERMATA.

Cidaris gaultina, Forbes.

* Lima globosa, Sow.
* Nucula bivirgata, Sow.
Ostrea.
Pecten orbicularis, Sow.
Pinna tetragona, Sow.
Plicatula gurgitis, Pict. & Roux.
Spondylus sp.
Teredo sp.

ScaPnopoDa.

* Dentalium decussatuin, Sow.

*Pentacrinus Fittoni, Austen.
GASTEROPODA.

ANNELIDA. Aporrhais sp.

Serpula sp.
CrPHALOPODA.

CRUSTACEA. :
* Belemnites minimus, Lister.

Haiites sp.
* Hoplites splendens, Sow.
* Hoplites tuberculatus, Sow.
* Schlanhachia Bouchardiana, Sow.
* Schlanbachia rostrata, Sow.
* Schlenbachia varicosa, Sow.

* Pollicipes levis, Sow.
BRACHIOPODA.

* Terchratula biplicata, Sow.
Terebratulina triangularis, Ether.

LAMELLIBRANCHIATA.

* Cardita tenuicosta, Sow. Pisces.

*Inoceramus tenuis, Mont.
Inoceramus sp., ef. concentricus,

Park.

*Lanna appendiculata, Ag.
Sedphanorhynchus rhaphiodon, Ag.

All these are also recorded from the various members of the
Upper Gault of Folkestone. The most abundant forms are ace
Inoceramus tenwis, Schlenbachia varicosa, Terebratula biplicata,.
Cardita tenwicostata, and Lamna appendiculata; and the general
aspect of the fauna suggests a correlation with the upper part of the
zone of Schlanbachia varicosa, Bed IX of Mr. Hilton Price’s Folke-
stone Gault. The species marked with an asterisk are common to the
two beds. Most of the other species have somewhat wide ranges,
but the occurrence of Terebratulina triangularis is notable. This
fossil abounds in the Cambridge Greensand, and is not generally
supposed to extend much below that horizon ; its occurrence in the
Hard Band is, however, undoubted, and several specimens of it
have been met with. The record of Schlenbachia rostrata, unfor-
tunately, is not so satisfactory ; but large pieces of an ammonite,
which may be Schl. rostrata, are very abundant in the clay just above
the Hard Band.

From this new paleontological evidence, and from the fact that
the fossils mentioned are all obtained some 40 feet below the upper
surface of the Gault, I conclude that the whole of the Upper Gault
of Cambridge was not used up in the making of the Cambridge
Greensand, but that a thickness of at least 45 feet of it remains at

? Quart. Journ. Geol. Soc. vol. xxx (1875) p. 351.

Vol. 60. ] LIMESTONE AT BARNWELL. 363

Barnwell. This, with the knowledge that the Gault as a whole is
thinning northward and passes into the Red Chalk of Hunstanton,
further complicates the problem of the Cambridge Greensand ;
but into that problem I cannot enter here.

In conclusion, I gladly express my thanks to Mr. R. H. Rastall,
of Christ’s College, for help in collecting the fossils here recorded;
also to Mr. H. Woods and Mr.‘A. J. Jukes-Browne, of St. John’s
College, for encouragement and aid in the identification of some of
the species.

Discussion.

The Presipent welcomed the Author's first paper to the Society,
which he hoped and believed would be followed by many others.
He thought that the Upper-Gault age of these beds was proved by
the fossils. Mr. Jukes-Browne, who had done so much work in
this district, seemed to speak with great caution as to the absence
of Upper Gault in Cambridgeshire. The speaker was inclined to
think that the deposit would prove to be local in the county, having
been removed elsewhere by denudation not necessarily indicating
upheaval, but rather the local action of eroding marine currents.

The Rev. J. F. Brake agreed that the ammonite-fauna exhibited
consisted essentially of Upper-Gault forms; and these being found
below some 40 feet of Gault-material, proved that the Upper Gault
had not been removed from the area. These beds had not been
noticed by earlier writers, from the fact that they had never been
exposed; there never had been 40 feet of Gault exposed in any
working below the coprolite-bed. The fossils exhibited were
markedly distinct from those of the ‘Cambridge Greensand’. The
latter could not have been derived from them; and their presence
at this depth threw doubt upon their ever having been reached by
denudation anywhere in the district.

The Autor thanked the Fellows for their reception of his paper.
In reply to the suggestion that the Upper Gault of Barnwell was
merely a local ridge which had escaped erosion during the formation
of the ‘Cambridge Greensand’, he pointed out (1) that the total
thickness of Upper and Lower Gault at Barnwell was less than that
shown in any of the well-sections south of Cambridge ; (2) that the
yield of phosphate-nodules and fossils from the former coprolite-
workings on the site of the present Gault-pit at Barnwell was
large, and that the ‘derived’ fauna contained therein included
Lower as well as Upper-Gault forms; and (3) that the Gault-pits
at Barrington and Arlesey which showed the junction of Gault and
Chalk-Marl yielded numerous Upper-Gault lamellibranchs, and that a
well-section at the latter place had proved the existence of a ‘ Hard
Band’ like that at Barnwell, but at an even greater depth.

2Eue

S64 MR. H. H. ARNOLD-BEMROSE ON | Aug. rgo4,

26. On some QuarrzitEe-Dykes in Movuntarn-LiMesrone near
SNELsTON (DERBysHIRE). By Henry Howr Arnorp-Bemrose,
Ksq., M.A., F.G.S. (Read May 11th, 1904.)

[Puarns XXX & XXXI.J

LI. DEscRIPTION OF THE QUARRY AND THE DykkEs.

Azsour 34 miles south-west by south of Ashbourne, near Snelston
Common, is an inlier of Mountain-Limestone surrounded by Keuper
Marl. According to the Geological-Survey Map, the outcrop of
limestone is roughly elliptical in shape, the major axis extending
for a distance of about half a mile in a north-north-easterly
direction, and the minor axis in a west-north-westerly direction
for about one eighth of a mile. Cockshead Lane, the road from
Norbury to Cubley Common, passes over the inlier, which only forms
a slight feature in the landscape, at a height of about 600 feet above
Ordnance-datum. Onaclear day, some of the churches and chimneys
of Derby, distant about 11 miles, can be seen from the top of the
quarry.

The limestone has been quarried on both the north and south
sides of Cockshead Lane for about 40 feet below the ground-level,
so that the lane passes over a high wall of limestone-beds, which
have been left intact between the two quarry-floors. The northern
quarry is now disused. It contains lead- and copper-ores, which
were worked about 30 years ago. It is outside the area of the main
mass of Mountain-Limestone to which the curious lead-mining laws
apply, and I was informed that the present owner does not allow
the lead-ore to be worked.

The quarry south of Cockshead Lane is being worked for road-
metal. The inlier is in the form of a dome or pericline, with its
greatest extension in a north-north-easterly direction. Only a
brief examination is necessary to show that the limestone varies
considerably in character in different parts of the quarry. It is
generally a massive limestone, with a few chert-nodules in the upper
part ; at the south-western end of the quarry the grey limestones
are seen dipping south-westward at an angle of 30°. They are
probably the highest beds in the quarry. ‘he central portion of
the dome has been removed down to the present floor, so that it is
uncertain whether the thin limestones extended over the whole area
at the time when the quarry was first opened, or whether they had
been removed by denudation.

Some parts of the rock-face show a BGcheneied surface, due to
differential movement on opposite sides of the nearly-vertical
joints. The rock in many places has a broken appearance, and
contains small hollow spaces or caverns; large portions of the
limestone have been partly or completely dolomitized, and are of

Vol. 60. | QUARTZITE-DYKES IN MOUNTAIN-LIMESTONE. 365

a brown colour. Ina hand-specimen the partly-dolomitized rock
is speckled with brown spots, which with a lens are seen to consist
of erystals and groups of crystals of dolomite.

The floor and faces of the quarry are traversed by vertical veins
or dykes of calcite, fluorspar, barytes, calcareous sandstone, and
quartzite. On my first visit, | noticed several blocks of siliceous
rock, which I was informed had been obtained from a so-called
bastard limestone on the south-eastern side of the quarry, and
that 20 tons of this rock had been removed. The place from
which it was obtained is now covered with soil and vegetation,
and consequently no outcrop is visible. The bastard limestone or
quartzite probably filled a fissure, pipe, or swallow-hole in the
limestone.

Pl. XXX, fig. 1, shows one of these dykes traversing the face
of the quarry. It varies from 2 to 4 inches in width, and consists
mainly of quartzite, but barytes and calcite are also found in it in
places. It is darker than the limestone and very hard.

Pl. XXX, fig. 2, shows another dyke, which attains a width of
19 inches, and consists of a hard sandstone or quartzite.

IL. Perroerapuy.

(1) The Quartzite-Dykes.

A number of thin slices of the quartzite and of the limestone
were examined under the microscope, but it will be sufficient for
the purposes of this paper to refer to the following.

No. 1316," from the 4-inch vein, examined under the microscope,
cannot be distinguished from a quartzite. It consists of angular and
detrital quartz-grains with enclosures, a few small pebbles or grains
of felspar, and a few shreds of mica. The grains are cemented by
silica, and sometimes by calcite ; the interspaces are often filled with
a secondary growth of quartz around the grains. (See Pl. XXXI,
fig. 1.) The hmestone (1315) in contact with the quartzite is fine-
grained and crystalline.

A specimen from a softer dyke (1318) consists of quartz, a small
quantity of mica, and traces of monoclinic felspar. The quartz-
grains are both angular and well-rounded. The formation of
secondary silica in optical continuity with the original grains is well
shown, and calcite is also present. (See Pl. XXXI, fig. 2.)

A specimen (1235) from another dyke consists of quartz-grains
and a few felspars cemented by calcite (see Pl. XXXI, fig. 3).

In the south-eastern face of the quarry, near where the bastard
limestone was worked, is another dyke of quartzite, which extends
to the topmost exposed bed. The rock (1086) consists of quartz,
with a small quantity of felspar and mica. Some of the felspars

1 These numerals throughout refer to the numbers of the slides in the
writer’s collection.

366 MR. H. H. ARNOLD-BEMROSE ON | Aug. 1904,

have straight extinction, but others extinguish up to an angle of
182, (See: Pls KOS te 4)

On a visit to the quarry this year at Easter, I was told by the
foreman that some silver-sand had been found in a small fissure
or joint in the limestone. J examined the fissure, and obtained some
sand of a reddish-brown colour, After it had been washed it
was examined under the microscope, and found to consist mainly
of quartz-grains, the majority of which were well-rounded, with a
few flakes of white mica.

(2) The Quartzose Limestone.

The rock (1232) in contact with the last-described dyke consists
of crystalline caicite, containing a large quantity of quartz in isolated
crystals and in granular aggregates. The quartz sometimes encloses
calcite. Two feet below No. 1232, the limestone (1233), which is in
contact with the same dyke, contains traces of organisms and many
bipyramidal crystals of quartz.

A thin slice (1234) of the partly-dolomitized limestone was
examined. It consists of remarkably well-defined and often isolated
rhombohedra of dolomite, in a matrix of finely-crystalline calcite.
The quartz occurs in granular aggregates and in isolated crystals.
A small piece of the rock was dissolved in strong hydrochloric acid,
and the residue was found to consist of bipyramidal quartz-crystals
and a small quantity of brown material.

Quartz-crystals were also found in other parts of the limestone.
The thin grey limestones at the south-western end of the quarry
are traversed by small calcite- and quartz-veins.

The thin slice (1236) consists of a limestone containing fora-
minifera, Calcisphera, and a few isolated crystals of quartz. ‘The
slice is traversed by a small vein of quartz in a fine mosaic, similar
to the quartz-strings or veins in the limestone near Bonsall.’

These quartzose limestones are similar to those described by me
in a paper read before this Society in the year 1898.”

°

(3) The Calcite.

Between the thin beds of limestone at the south-western end of
the quarry and the 4-inch quartzite-dyke described above, is a
vein of calcite several feet thick. It appears in part to be bedded
like limestone, and shows horizontal slickenside-faces between the
joints. It consists (1237) of crystalline calcite, with polysynthetic
twinning well developed. Some portions are red, and are similar to
the ‘ Hartington Red,’ formerly obtained near Hartington between
Ashbourne and Buxton, and polished as marble. Other portions
are white. ‘The red coloration is due to oxide of iron, which occurs
in small dendritiform patches.

> Quart. Journ. Geol. Soc. vol. liv (1898) pp. 175 & 174, thin slice No, 431.
2 Ibid. pp. 169 to 182.

Vol. 60. | QUARIZITE-DYKES IN MOUNTAIN-LIMESTONE. 307

IIL. Srzica PRESENT IN TWO ForRMs.

From the foregoing description, it appears that the silica is present
in the limestone in two forms, which have had an entirely-different
origin. The one, similar to that in the quartzose limestone previously
described by me as occurring in various parts of the Mountain-Lime-
stone area of the county ; and the other associated with felspar and
mica, sometimes forming a calcareous grit, at others a quartzite.
In the former case, the quartz occurs in isolated crystals and crys-
talline aggregates and in small veins or strings in the limestone ;
in the latter, it occurs in dyke-like masses, which mainly consist of
detrital and angular grains.

It may be convenient to refer briefly to sandstone-dykes which
have been previously described. The references to them have been
obtained from Sir Archibald Geikie’s ‘Text-Book of Geology,’ 4th
ed. vol. i (1903) pp. 665-67 :—

(z) In Ross-shire narrow rifts or cracks in Lewisian Gneiss have been filled
with Torridonian conglomerate and sandstone.

(4) Dykes of hard fossiliferous sandstone traverse the Neocomian clays of
Alatyr, in Russia. These clays are supposed to have been rent open by a
submarine earthquake, and filled up with deposits from the sea-floor.

(¢) InColorado a series of sandstone or quartzite-dykes traverse a pre-Cambrian
granite. Mr. W. O. Crosby suggests that the fissures were formed at the time
of the production of the great fault of Ute Pass, and that they were filled
with sand from the overlying Potsdam Sandstone.

(dZ) In Northern California Mr. J. S. Diller found dykes of impure quartzose
sandstone intersecting Cretaceous sandstones and shales along lines of joint,
and suggested that they represented earthquake-fissures filled in with sand
rapidly injected from below. .

(¢) Mr. E. Greenly described some sandstone-pipes in limestone in Anglesey,
descending from a bed of sandstone into a limestone.

LV. OrreIn oF THE QUARTZITE-DYKES IN THE
Livestone-LNiier.

The detrital form of the quartz-grains and the slight traces of
bedding seen in one of the dykes indicate that the quartz, mica,
and felspar were introduced into the limestone-fissures from above.
According to the Geological-Survey Map, the Keuper Mar! rests upon
the limestone in the neighbourhood of the quarry. The sections seen
in the quarries seem to indicate that this mapping is correct. In
trying to find an explanation of the origin of these quartzite-dykes
in the limestone, I examined the neighbourhood of the quarry for
sections of Keuper rocks in the year 1901. At Marston-Common Farm,
1200 yards south-west of the quarry, I found that a well was being
sunk for water. It was started in Keuper Marl, went through 8 or
10 yards of it and 21 yards of a very hard grit or quartzite, which
was sometimes in thin laminz and at others contained small pebbles
of quartzite. At the time of my visit, the work had just been
abandoned, because of the absence of water. The information and
measurements were obtained from one of the men who were engaged
in the work. I made a selection of specimens of the quartzite from
the sinking, and examined several thin slices.

=

368 MR. H. H. ARNOLD-BEMROSE ON [Aug. 1904,

The rock is similar to the quartzite that occurs in the dykes in
the quarry. Shdes 1238 & 1239 consist of quartz in a mosaic of
granitic structure, with a small quantity of mica and pebbles
of microcrystalline quartz (see Pl. XXXI, fig. 5). The laminated
quartzite (1249) shows the laminations better in a hand-specimen
than under the microscope, and contains more mica than 1238 &
1239. A thin slice of Nuneaton quartzite, compared with Marston
rock, was found to contain larger grains of quartz, but in other
respects to have a similar structure.

The failure to find water was probably because the sandstone-
grains were cemented by secondary silica, which had rendered the
rock impervious to water.

About 800 feet south of Marston-Common Farm is an old sand-
stone-quarry, on ground mapped as Keuper Marl by the officers of
the Geological Survey. From its position and from the fact that
the ground-surface is lower than that at the farm, we may infer that
the sandstone-beds are probably on the same horizon as the quartzite
found in the well. Two thin slices of this rock were examined
(1319 & 1820). They are similar to some of the quartzite-dykes in
the quarry. The rock consists mainly of an aggregate of quartz-
grains, with a small quantity of mica, and perhaps of felspar.
Some grains consist of microcrystalline quartz. (See Pl. XXXI,
fig. 6.)

VY. Concrvsions.

The Snelston inlier consists of massive beds of limestone with
occasional nodules of chert, and is unaccompanied by shales; 1t must,
therefore, belong to fhe main mass of the Mountain-Limestone,
though separated from it by a large synclinal basin. The quartzite
in the dykes is similar to the Keuper Sandstone in the immediate
neighbourhood of the limestone-inlier. It requires no great stretch
of imagination to suppose that the limestone, traversed by joints and
fissures, was covered by water in which the Triassic sandstones were
jaid down. ‘The angular and rounded grains of quartz, with the few
felspars and fragments of mica, were probably deposited in these
fissures, and solidified as dykes of sandstone. At a later period, the
silica was introduced which cemented these sandstone-dykes and
the sandstones at Marston-Common Farm into a quartzite, and
impregnated the limestone in such a way as to form a quartzose
limestone similar to the quartzose limestone near Bonsall, Castleton,
Ashover, and in other parts of the county.

EXPLANATION OF PLATES XXX & XXXI.
Puate XXX,
Quartzite-dykes in Mountain-Limestone near Snelston (Derbyshire).

Fig. 1. Four-inch dyke of quartzite, passing through the limestone in a vertical
direction near the centre of the figure.
2. Larger dyke of quartzite, 10 to 12 inches in diameter. The quarry-face
is aslickensided surface.

[Both figures represent an almost vertical face of the quarry-wall. |

QuaRT. JOURN. GEOL. ‘Soc, VoL. EX; “Pi. XXX:

ee % s

Hi. i B., Photo. | ae Derby.
QUARTZITE-DYKES IN MOUNTAIN-LIMESTONE,
NEAR SNELSTON (DERBYSHIRE)

*- ey ve
Ls aii a

A be

in iP
: 4

Quart. JOURN. GEOL. Soc. VoL. LX, PL. XXXI.

Fic. 1 x 50. Fig. 2 x 50.

Fic. 6 x 50.

¥Nign

H.A.B., Photomicro
| ; Bemrose, Colla

QUARTZITE IN MOUNTAIN-LIMESTONE AND KEUPER SANDSTONE.

Vol. 60.] QUARIZITE-DYKES IN MOUNTAIN-LIMESTONE, 369

PLATE XXXII.

[The figures were photographed by the Author from the microscope, under
polarized light with crossed nicols, and enlarged 50 diameters. |

Fig. 1. Thin slice (1316) from the 4-inch dyke shown in Pl. XXX, fig. 1.
See p. 365.

2. Thin slice (1318), showing the formation of secondary silica in optical
continuity with the rounded quartz-grains, from a second dyke. See
p. 565.

5. Thin slice (1285), quartz and felspar cemented by calcite, from a third
dyke, See p. 365.

4. Thin slice (1086), quartz and felspar, from a fourth dyke. See p. 365.

5. Thin slice (1238) from Marston-Common well: quartzite. A piece of
mica is seen near the centre of the figure. See p. 368.

6. Thin slice (1319) from the quarry south of Marston-Common Farm :
sandstone. See p. 368.

Discussion.

The Caatruan (Mr. H. B. Woopwarp) remarked that the subject
of sandstone-dykes had not been brought before the Society, except
incidentally, for more than 60 years—-when Strickland called
attention to the remarkable dykes of calcareous grit in Cromarty.
It was difficult to'say whether those particular dykes were filled from
above, or by hydrostatic pressure from below, as they were seen
only in plan and not in section. In some cases wind-drifted sand
might have filled fissures.

Prof. Jupp referred to the case in Cromarty which was supposed
by Murchison to be a ‘ trap-dyke’, but was afterwards shown by
Hugh Miller to be composed of sandstone and actually to
contain fossils. He suggested that the fissure might have been
formed by earth-movements or solution, subsequently to the
deposition of the Keuper Sandstone, but before its consolidation.
As the fissure was opened, the sand from above might gradually
find its way downward, and would at last be converted by soluble
silica, traversing the mass, into quartzite.

Mr. Srrawan remarked that he had described veins of quartzite
in the limestone of Flintshire.’ In the Talargoch Mine some of the
veins contained an impalpably-fine siliceous sand, which passed in
its unweathered state into a quartzite resembling that described by
the Author. Such deposits tended to fill any fissure or cavity
in the limestone, and might be derived from any overlying sand-
stone, whether a bed interstratified with the limestone or, as in
the case referred to, from the chert-beds of the Millstone-Grit. At
Talargoch there was no Keuper Sandstone overlying the limestone,
and he was not satisfied that the material described by the Author
had been derived from that formation.

The Rev. H. H. Wiywoop said that he was much interested in
the description of the ‘dykes’, a formation with which he was very
familiar in the Mendip district, where the joints in the Mountain-
Limestone were filled up by Liassic and Triassic deposits: these,

' *Geology of Rhyl, &.’ Mem. Geol. Surv. (1885) pp. 47-48.

27) MR. H. H. ARNOLD-BEMROSE ON [Aug. 1904,

being less easy to work than the adjoining limestone, were left by
the workmen in quarrying, standing out like walls. There could
not be any doubt that these joints had been filled in from above.
In a quarry near Chipping Sodbury these infillings assumed
a columnar form, and consisted of sandstone with white quartz-
pebbles, probably the result of the denudation of the Triassic sand-
stones which once covered the district and were washed in and
finally consolidated.

Mr. H. W. Moncxron complimented the Author on the beautiful
photographs of rock-faces shown upon the screen. He then referred
to the curious bands of hard calcareous sandstone which run through
the Kimeridge Clay at Ethie near Cromarty, and appear to be of
much the same nature as those described in the paper. The ‘ dike’
at Ethie is harder than the shale, and stands well above it on the
shore. It is probably an infilled crack or fissure in the shale ; for,
as the country-rock is (in that case) shale, the space occupied by
the ‘ dike’ cannot have been due to solution. The speaker thought
that the infilling had probably come from above, although he could
quite understand that such a ‘ dike’ might be formed by infilling
from below, somewhat on the principle of creep in coal-pits. He
did not think that the word ‘ dike’ should be confined to bands of
rock of igneous origin, for the word was a common one, and
in Scotland usually meant a wall. He thought that it was a good
term for the bands of rock in question.’

Prof. W. W. Warrs asked whether the Author had considered
the possibility of the dykes being of Millstone-Grit age. He had
examined examples of Millstone-Grit in which the secondary
growth of quartz was precisely similar to that described in the
paper. Prof. Sollas’s observations in Funafuti had shown that
the reef-limestone was seamed with deep fissures admitting sea-
water, and if the Carboniferous Limestone was formed under similar
circumstances, the oncoming Millstone-Grit would find the requisite
hollows for the formation of steep dykes such as those described by
the Author. The speaker had seen dykes of this nature, not only in
soluble rocks, but in quartzites like those of the Lickey Hills, and
in this case the dykes frequently contained Llandovery fossils.

Mr. Tratt referred to the dykes and veins of sandstone in the
Lewisian Gneiss of the North-Western Highlands, and pointed out
that they occurred at or near the junction of gneiss and Torridon
Sandstone. They were similar in petrological character to the
sandstone, and had no doubt been filled in from above.

Mr. J. Atten Howe remarked that, a few miles north of
Snelston, near Brassington, large pipes and fissures existed in the
limestone, containing a mixture of sands and clays of Keuper,
Bunter, Millstone-Grit, and possibly of Glacial origin. He asked
the Author whether the dykes described in the paper were in
any way related to the above deposits, an occurrence which seemed
not unlikely, considering their proximity to Snelston. The sand in

2 See, in confirmation of this, John Brand’s ‘Hist. of Newcastle’ vol. ii.
(1789) p. 679, note d.

oO,

Vol. 60. ] QUARIZITE-DYKES IN MOUNTAIN-LIMESIONE. O71

the pipes was frequently re-crystallized, and flakes of mica were
abundant. There was no doubt that the pipes had been filled
in from above. There were, however, certain features in the
Snelston outlier which appeared to present a parallelism to those
dyke-districts described by Diller, Crosby, and others, in which the
dykes had been filled by hydrostatic pressure from below; then,
Snelston was very near a minor earthquake-centre, and had clearly
been subjected to pressure resulting in a fracturing or buckling
of the strata. He suggested that the Author might notice whether
the mica-grains were lying parallel to the sides of the dykes, or at
right angles to them ; for it had been indicated by the American
investigators that the former position was characteristic of dykes
filled from below, while the latter position was the rule in dykes
filled trom above.

The Avruor thanked the Fellows for their reception of his paper.
He thought it more likely that the sandstone had been introduced
from above, than through several thousand feet of limestone from
below. Although the sand might possibly be of Millstone-Grit age,
the presence of Keuper Sandstone in the immediate neighbourhood
of the limestone-inlier probably indicated the true source of the
sand.

The pits in the limestone filled with sand, shale, and Bunter
pebbles, mentioned by the previous speaker, were very different
from the dykes or veins described by the Author. He hoped that
the facts described in his paper would one day be useful to some
geologist, who would be able to explain satisfactorily the origin
of sandstone-dykes in sedimentary rocks.

oi2 MR. J. V. ELSDEN ON THE AGE OF [Aug. 1904,

27. On the Age of the Liyn-Paparn Dyxes. By James VINCENT
Espen, Esq., B.Sc. (Lond.), F.G.8. (Read May 25th, 1904.)

[Puatn XXXII—Mrcroscorn-SEcrions. |

Il. Lyrropucrion.

Tne characters of the basic sills of Caernarvonshire have been
described in detail by several writers, notably by Mr. Harker in his
well-known essay on the Bala Volcanic Series. There is a marked
absence of dykes in association with the outbursts of this period,
aud the numerous basic dykes of this area have generally been
assigned to a later series of eruptions. The evidence upon which
this assumption rests is, however, not always satisfactory ; and
although Mr. Harker is inclined to favour their post-Carboniferous
age, he does not conceal the uncertainty of this conclusion in
several cases, and he adduces evidence which seems to point, at
least in some instances, to the possibility of the existence of more
than one group of these intrusions.’ Dr. C. A Matley, also, finds
that in Northern Anglesey at least two groups of dykes occur, of
which the earlier are pre-Silurian and the later post-Ordovician.”
But Mr. E. Greenly maintains that the later dykes of Anglesey,
including those of the Menai Straits, are certainly post-Carboni-
ferous, and may possibly be even of Tertiary age.’

With regard to the Llyn-Padarn dykes, with which this paper is
chiefly concerned, no very detailed description appears to have been
published, although several authors have incidentally referred to
them, as will be mentioned hereafter. It appears to have been
generally assumed that these dykes are of the same age as those of
the Menai Straits, to which they are supposed to bear a general
resemblance, both in petrographical character and in direction.
With regard to the former, however, this is by no means the case.

In the present paper it is proposed to examine this question in
detail, and to produce evidence which seems to suggest that the bulk
of the ‘ greenstone -dykes of this area belong to an earlier period
of eruption than has been generally assigned to them, and there is
proof that some of these ‘greenstones* may even be older than the
quartz-felsite of the Llyn-Padarn ridge. The greater part, however,
if not actually of Bala age, seem to have been intruded before
the great post-Bala crust-movements, which produced the folding
of the Lower Cambrian rocks of Llanberis, had entirely ceased.
At the same time, the evidence does not exclude the possibility that
some of the intrusions may be of a later date.

The evidence upon which these conclusions rests is based mainly

* On some Anglesey Dykes’ Geol. Mag. 1887, p. 409; & chid. 1888, p. 267.

~ ‘Geology of Northern Anglesey’ Quart. Journ. Geol. Soc. vol. lvi (1900)
p. 249.

* *On the Age of the Later Dykes of Anglesey’ Geol. Mag. 1900, p. 160.

—

Vol. 60.1] THE LLYN-PADARN DYKES, 373

upon the signs which the intrusions exhibit of having been con-
siderably modified by earth-pressures, more especially in those
portions which protrude into the Cambrian strata. Petrographical
considerations, also, make it impossible to separate these rocks from
the diabase-sills of Bala age occurring farther to the south and
south-west of this area; and there is a strong presumption that
they represent the last residuum of the magma from which the Bala
sills were derived.

II. Fiecp-Evivence.

The greater part of the basic dykes of Llyn Padarn have a south-
easterly strike, and several of them penetrate both the older ridge
and the later Cambrian strata which abut upon it. Mr. Harker
has given very strong reasons for supposing that the ridge stood up
as a more or less firm buttress, against which the Llanberis Slates
and Grits were forced by the great south-easterly thrust which took
place after the commencement of the eruption of the Bala diabases.*
The duration of this thrust is uncertain, but there does not appear
to have been, in this area, any later movement of a magnitude
sufficient to cause such a structural alteration as these rocks exhibit
in certain parts.

A careful examination of these dykes discloses the fact that
whereas the north-western portions, which are enclosed in the older
rocks of the ridge, are comparatively free from dynamic meta-
morphism, this character gradually disappears as the dykes are
followed into the more yielding Cambrian grits and slates, where
they become structurally deformed, and often so highly sheared as to
become with difficulty recognizable as portions of the same dyke.
This feature is not confined to a few instances. It is shown in every
case that has come under my notice. Taking, for example, the long
dyke shown in the map (p. 376) south of Cwm-y-glo, this rock
preserves the character of a typical ophitic diabase, until near Gallod
it emerges into the Cambrian sediments. Here its course changes,
and it shows a curve concave to the south, as it winds upward to the
summit of Y Bigil. At the same time, the appearance of the rock
alters, its original structure being altogether obliterated by crushing,
and its sheared end has acquired an almost siaty cleavage.
Accompanying this structural alteration the mineralogical changes
are no less pronounced, as will be more fully detailed in another
section of this paper.

Similar features may be noticed in tracing the other dykes in
the two areas east and west of Llyn Padarn. The dykes in the
ridge on the western side of the lake show only the effects of
slight shearing and pressure-metamorphism, while those in the
sediments on the eastern side, about Fachwen and Yr Alt Wen,
are crushed almost beyond recognition. Not a single example of
the many exposures of ‘greenstones’ in the Cambrian sediments,

1 «Bala Volcanic Series of Caernarvonslire’ [Sedgwick Prize Essay for
1888] 1889, p. 114.

37 MR. J. V. ELSDEN ON THE AGE OF [Aug. 1904,

examined by me, failed to exhibit this character in greater or
less degree. It is, in fact, so distinctive, that specimens can often,
by the unaided eye, be at once assigned to one or the other of
these two regions.

An interesting exposure exhibiting these conditions has quite
recently been opened up at Llanberis, where blasting has taken
place in connection with an alteration in the road, about a quarter
of a mile to the south-west of Plas Coch. This occurs at the top
of the hill a little beyond the smithy, where a small ‘ greenstone ”-
intrusion, about 5 yards wide, is to be seen near the base of the
Lingula-Flags. (The same rock is visible in the bed of the Afon
Goch close at hand, but the course of the dyke is not visible
for any great distance.) Apparently the outcrop of this dyke runs
nearly parallel to the strike of the Zingula-Flags, which here
dip almost vertically ; yet, whether the intrusion is a dyke or sill
is not quite certain, although the evidence seems to favour the
former interpretation. It is here manifest that the igneous rock
has been powerfully affected by the crush which folded the sedi-
mentary rocks. ‘The southern side has been much broken and
faulted against the flags, while the northern contact is cleaner and
less crushed, a circumstance which might be expected when the
southerly direction of the thrust towards the north is borne in
mind. The whole mass of the igneous rock is greatly sheared,
becoming in places almost schistose, the fissures and shear-planes
thus produced being strongly marked by veins and coatings of silky
asbestos, some of which are nearly 2 inches wide, the asbestos-fibres
being arranged transversely to the walls of the fissures. The rock
itself is of a light greenish-grey colour, spotted with dark patches
of a chlorite-mineral. There is also much secondary calcite, with
fan-shaped bundles of epidote in the more weathered portions.
A quartz-epidote vein about 18 inches wide traverses the rock in
its lower portion near the road-level on the northern side. The
rock contains a good deal of pyrites, and the flags at the junction
are filled with cubes of this mineral, many of which have been
weathered out, or replaced by chloritic pseudomorphs. The petro-
graphical features of this rock will be referred to later.

The exposure in the Afon Goch is exactly similar to the foregoing,
and need not now be enlarged upon. There can be no sort of doubt
with regard to the age of this intrusion, which must have preceded
some part of the earth-movements connected with the post-Bala
folding. Previous observers have already called attention to the
effects of intense pressure upon the rocks on the southern margin
of the quartz-porphyry ridge. Sir Archibald Geikie describes basic
dykes near Llyn Padarn which have been converted into a slaty
rock by pressure.’ Similar sheared diabases have been noticed by
the Rev. J. F. Blake *; consequently, there appears to be cumulative
evidence that these ‘greenstones,’ if not actually intruded before the
period at which the curvature and compression of the region took

1 « Ancient Volcanoes of Great Britain’ vol. i (1897) p. 162.

2 «On the Felsites & Conglomerates between Bethesda & Llanllyfni’ Quart.
Journ. Geol. Soc, vol. xlix (1893) p. 441.

—_—_

Vol. 60. | THE LLYN-PADARN DYKES. 375

place, were certainly injected before these great earth-movements
had died away.

To sum up the field-evidence on this point, we find in these
dykes unmistakable signs of dynamic metamorphism and de-
formation. It would not be expected that those portions of the
dykes which were firmly held in the Llyn-Padarn ridge would be
so profoundly affected by the post-Bala movements as those enclosed
in the more yielding sedimentary strata towards the south, and this
agrees precisely with what appears to have taken place. The pro-
gressive examination of these dykes from one extremity to the other
firnishes many interesting examples of the effects of varying degrees
of pressure- -metamorphism, to certain of which attention will shortly
be drawn.

It must not be supposed, however, that highly-sheared and altered
‘ greenstones’ do not.occur in the Llyn-Padarn ridge. I have found
several instances of these, and it is suggested that they may belong
to a still older group.

I do not prepose to reopen the controversy with regard to the
stratigraphical succession in this district, but taking ee conglo-
merates on either side of the Llyn- Padarn ridge as the base of Be
Cambrian, the evidence for the existence of pre- -Cambrian greenstones
will now be considered. Previous observers have called attention
to the occurrence of fragments of basic igneous rocks in the con-
glomerates, and have expressed some difficulty in refering these to
their origin. The Rey. J. F. Blake has described the occurrence at
Bryn Efail, on the north side of the Llyn-Padarn ridge, of felsite
intrusive in a rock which he believed then to be a slate,’ but
Miss Raisin has since shown this to be a sheared ‘greenstone’.* It
should perhaps be mentioned that the latter observer failed to see
any vidence of the intrusion of the felsite into the ‘ greenstone ’.
W ithout, however, entering into the discussion of the Bry n-Efail
section, hod whith a great deal has been written by the above-
mentioned authors, the following fact appears to the present writer
to furnish independent proof Fiat there is in the Llyn-Padarn ridge
a ‘ greenstone’ older than the quartz-felsite.

Passing along the road which runs from the bridge at the lower
end of Llyn Pedars along the eastern shore of the lake, near the
point where this road crosses the slate-railway (marked A on the
sketch-map, p. 376), there is an exposure of ‘ greenstone’ which
appears to have been opened up by blasting comparatively recently.
To all appearance, this rock resembles the ordinary basic dykes which
penetrate the quartz-felsite in this locality, but it has evidently
been much sheared.

1 T. G. Bonney & C. A. Raisin, ‘On the Relations of some of the Older
Fragmental Rocks in North-Western Caernarvonshire’ Quart. Journ. Geol.
Soe. vol. 1 (1894) p. 578.

2 ‘On the Cambrian & Associated Rocks in North-Western Caernarvonshire '
Ibid. vol. xliv (1888) pp. 283, 284.

3 «On the Lower Limit of the Cambrian Series in North-Western Caer-
naryonshire’ Zhid. vol. xlvii (1891) p. 337.

Sketch-map of the Llyn-Padarn district.

376 MR. J. V. ELSDEN ON THE AGE OF [Aug. 1904,

The contacts with the felsite on each side look fairly clean and
regular ; but, near the centre of the exposure, which is about 10 feet
wide, the ‘ greenstone’ is penetrated by a tongue of felsite, about
2 inches broad near the upper exposed part, and tapering to a
point at the lower extremity. The length of this tongue is about
2 feet.

1 mile.

SCALE:

_ Bigil

inches

Spy tty

NH
WHT
HTT
MUNNII(I Hag
it HAIN UH
| UT | |
| } WHI
{ WH} WT |
WH
| }
| |

»

Fachwen

represent dykes.

A thin slice of this rock, if examined beneath the microscope,
presents the appearance of a quartz-felsite, and resembles in all
essential features the descriptions given by Prof. Bonney of the
felsites of this area.' The section shows irregular subangular
blebs of quartz, giving somewhat undulose extinction, and

* 'T. G. Bonney, ‘On the Quartz-Felsite & Associated Rocks at the Base of

the Cambrian Series in North-Western Caernarvonshire’ Quart. Journ. Geol.
Soe. vol. xxxv (1879) pp. 311 et seqq.

Vol. 60.] THE LLYN-PADARN DYKES. 377

enclosing portions of the cryptocrystalline groundmass. The latter
is granular, and appears to consist almost entirely of quartz, and
possibly some felspar. There are also numerous laths of a greenish,
strongly-pleochroic mineral, with slightly-oblique extinction, which
may be microliths of hornblende. There is much opaque granular
matter, and some chloritic patches occur. The rock is apparently
modified slightly by contact with the ‘ greenstone.’

The ‘ greenstone’ in thin section shows abundant laths of felspar,
mostly replaced by micaceous aggregates, yet here and there
retaining the optical characters of a plagioclase. Augite is fairly
abundant, mostly altered to an opaque brownish substance, but
occasionally giving bright polarization-colours. There is also a
good deal of opaque leucoxene, resulting from the decomposition of
titaniferous iron. Calcite and chlorite-eyes are abundant, although
there is apparently no secondary quartz. The rock was originally
somewhat like the ordinary ophitic type of dyke-rocks in the Llyn-
Padarn ridge, the structure having been obliterated by shearing,
crushing, and alteration.

Although it would perhaps be going too far to generalize from this
single occurrence of an acid intrusion in the ‘greenstone,’ yet the
fact remains, and there does not appear to be any escape from the
~ conclusion that we have here a pre-Cambrian basic rock. There
are certain other highly-sheared and altered ‘ greenstones’ in the
Llyn-Padarn ridge, which may also belong to this group. A rock
from the locality marked C on the accompanying sketch-map (p. 376)
is so like the one described above, and differs in so marked a degree
from the unsheared rock in the neighbouring dyke south of Cwm-
y-glo, that it seems certain that it has been subjected to stresses
which have not influenced the Cwm-y-glo intrusion. Unfortunately,
I have not been able to discover any but outcrop-exposures of this
rock ; it is not unlikely, however, that when this district comes to
be mapped on the 6-inch scale, additional proofs will be forthcoming
that some of these highly-altered basic rocks are older than the
main dykes of the Llyn-Padarn ridge.

II], Perroeraputcat EvipENcr.

In considering the petrographical evidence as to the age of the
main portion of the Llanberis dykes (excluding those of pre-
Cambrian age), I shall now attempt to show that it is not possible
to separate these rocks from the Bala diabases upon general mine-
ralogical grounds; and that there are indications that these two
groups of rocks were in all probability derived from the same
magma-basin. At the same time, it must be remembered that, if
this supposition be correct, the low horizon at which the Llanberis
rocks occur might be expected to disclose certain divergences,
resulting from such a differentiation as might take place in the case
of the latest phase of an eruptive sequence. Although this point is
of the greatest interest, in view of the differentiation-theory put
forward by Mr. Harker to account for the sequence of the Bala

Q.J.G.8, No. 239. 20

378 MR. J. V. ELSDEN ON THE AGE OF [Aug. 1904,

rocks, it is also one of extreme difficulty ; and conclusions, based
upon such evidence, can only be drawn with very great caution.

In considering this portion of the subject, it will not be
advisable to recapitulate previous observations any further than
will be necessary to compare these rocks with the Bala diabases on
the one hand, and the post-Carboniferous dykes on the other. With
the former group Mr. Harker has already made us familiar.’
With all the more important features shown by the diabase-sills of
the eastern part of Caernarvonshire, these rocks agree down to the
smallest detail; though certain points, notably the frequent occur-
rence of secondary sphene and asbestos, but rarely exhibited in
Mr. Harker’s specimens, become very prominent in some of the
Llanberis dykes. The latter rocks are also sharply separated from
the post-Carboniferous dykes of Anglesey described by Mr. Harker,*
Mr. Greenly,* and Dr. Matley,* all of whom agree that the latter are
not very basic in character, possess no appreciable titanic acid,
have two distinct generations of felspar, and show no conspicuous
signs of pressure-metamorphism. The pyroxenes, also, in these
younger rocks belong to a later stage of consolidation, and are
apparently of a different chemical composition from those about to
be described.

It will be convenient to consider the minerals in the order of
their consolidation, and to divide the area into two parts, in
accordance with the previously-described differences shown in the
field-examination. These will be designated the dynamic or
crush-zone of the more yielding sedimentary rocks, and the static
or pressure-zone of the Llyn-Padarn ridge. These terms are used
for convenience of description only, for it is evident that a crush-zone
must also be a pressure-zone of greater intensity. Prof. Bonney
has called attention, in his paper on the crystalline schists of the
Binnenthal,° to the necessity for differentiating direct pressure from
shearing crush ; and he has proposed the term catathlastic for
structures produced by the former, in contradistinction to the
mylonitic structures produced by the latter. The former term,
however, does not appear to have been seriously contemplated, and
the distinction is not always easy to make, seeing that both structures
will be found together. In the present paper, the distinction
referred to above is only intended to mark the effects in the
rocks described, which are produced by the different kind and
degree of pressure In a soft, yielding mass and in the hard
resisting buttress against which the forces acted. Perhaps the
terms dynamic and static metamorphism, as suggested by
Prof. Judd,° might be sufficient to describe these two kinds of force
exerted upon a rock-mass by great earth-movements. Structurally,
all the rocks examined are, or once were, ophitic diabases. They

* «Bala Volcanic Series of Caernarvonshire’ 1889, pp. 75 e¢ seqq.
? Geol. Mag. 1887, p. 409 & ibid. 1888, p. 267.

* Ibid, 1900, p. 160.

* Quart. Journ. Geol. Soc. vol. lvi (1900) p. 247.

° Ibid. vol. xlix (1898) p. 104.

® Geol. Mag. 1889, p, 243.

ee ee ee

Vol. 60.] THE LLYN-PADARN DYKES. 379

do not, in their unaltered state, show any sign of a second
generation of felspar; but in the crush-zone this structure, as
might be expected, is obliterated, the ophitic pyroxene becoming
granulitic, while the parts which have experienced the most
intense shearing have become almost schistose. In some parts,
albitization has gone on to such an extent, that the broken
pyroxenes are completely enclosed in large secondary felspars,
causing a complete reversal of the original structure, the pyroxene
then having the appearance of being the first-formed mineral.

The general inference from all the slices is that consolidation
took place very slowly, probably under a thick cover of rock,
which may possibly explain the rarity of very marked sahlbands,
and certain cases of local enrichment in felspar, such as might
result from the concentration of this mineral, in accordance with
Soret’s principle, owing to a prolonged duration of the liquid state.
This condition is still further indicated by the phenomena presented
by the augite, as will be more fully described later.

The mineral-constituents of the rocks will now be described in
turn.

Apatite.

This mineral is present in conspicuous proportion in many of the
rocks of the Llyn-Padarn ridge area, but I have only occasionally
recognized it in the crush-zone. Mr. Harker mentions its general
occurrence in the Bala diabases. The capricious distribution of
this mineral in igneous rocks, and its usual immunity from any
marked effects of dynamic metamorphism, render it of little value
as an index to the amount of alteration which a rock containing it
may have undergone. For present purposes, therefore, it assumes
little or no petrographical importance.

Tron-Ores.

It will be convenient to consider the iron-ores next, although
these constituents did not entirely separate at any definite stage.
Some are idiomorphic, but they are also very commonly moulded on
the felspars and included in the augites. Generally speaking,
they agree so closely with Mr. Harker’s description,’ that it will
not be necessary to recapitulate these points. Titanic acid, how-
ever, appears to be more abundant in al! the specimens from the
Llyn-Padarn dykes, and secondary alteration has resulted in a
large quantity of sphene-granules, in addition to amorphous
leucoxene. Mr. Harker noticed granular sphene in the Bala
diabase in one locality only, namely, at Pant-Evan, Tremadoc,”
although he records its presence in some quantity in the
Llangwnad1 rock, where the intrusion is presumably on a somewhat
lower horizon. On the other hand, no titanic acid was recognized
in the hornblende-picrite of Penarfynydd. It is also notably
absent in the later dolerite-dykes. In the light of these facts, the

* * Bala Volcanic Series of Caernarvonshire ’ 1889, p. 80.
2 Ibid, p. 81.

380 MR. J. V. ELSDEN ON THE AGE OF [Aug. 1904,

plentiful occurrence of compounds of titanium in the Llanberis
rocks is of considerable interest.

Still more important is the evident connection between the altera-
tion of ilmenite and the amount of dynamic metamorphism which
the rocks have undergone, as Mr. Harker has already noticed in the
diabases of Eastern Caernarvonshire. Dr. Teall, also, has found the
mineral of great service in tracing the origin of certain schists from
sheared diabases.'_ These phenomena are well illustrated in the
Llanberis dykes, where every stage in the alteration of ilmenite may
be traced as the dykes are followed into regions of increased dynamic
influences. An interesting example of this alteration is seen in the
production of rutile from ilmenite, as previously described by Prof.
Cathrein.* This mineral occurs in one of the slides, in the form of
abundant hair-like microliths, associated with fragments of still opaque
leucoxene. Sphene in distinct granules, as well as the translucent
variety usually associated with leucoxene, is abundant. A notice-
able feature, however, of many of the yellowish-brown granules is
that they do not possess the high double-refraction of sphene, but
transmit only a feeble light between crossed nicols. A similar
appearance was noticed in the kimberlite of Kentucky by Mr. J. 5.
Diller,’ and by Dr. G. H. Williams in the serpentine of Syracuse,
in which cases chemical tests showed these grains to be perowskite.
It would not be possible to say definitely that these feebly double-
refractive granules in the Llanberis rocks are perowskite, merely
on account of their optical anomaly; but the possibility suggests
itself that a part of the rutile liberated from ilmenite has combined
with lime to form this mineral. A similar occurrence of this
presumed perowskite has been noticed by me in the diabase of
the Santon complex in the Isle of Man. It is, of course, not
necessary to assume that this mineral has been derived from ilmenite,
as its marked association with chlorite-areas might also suggest a
derivation from a pre-existing titaniferous pyroxene.

All the phenomena exhibited by the titanium-compounds in
these dykes, both as evidence of a richly titaniferous magma and as
proving extensive dynamic metamorphism, are highly characteristic.
It is, indeed, possible to trace the kind and degree of pressure-
alteration in the successive portions of these dykes by observation
of the titanium-minerals alone.

With regard to other iron-ores, such as magnetite and pyrites,
these present the usual characteristics, as described by Mr. Harker
in dealing with the Bala diabases, and they do not require further
description in this paper.

Felspars.

The felspar is always triclinic, and occurs usually in idiomorphic
crystals, with well-marked albite-twinning. Pericline-twinning 1s
| “British Petrography ’ 1888, p. 238.

* Zeitschr. f. Krystallogr. vol. vi (1882) p. 244.
° Bull. U.S. Geol. Surv No. 150 (1898) p. 294.

Vol. 60. | THE LLYN-PADARN DYKES. 381

seen in isolated instances. A prevalent combination shows one
half of a Carlsbad twin simple, and the other half with the albite-
lamellation. The usual form is in long laths, and in the uncrushed
parts the extinctions are sharp. On sections oriented in the zone
100 on 001 the extinction-angle generally exceeds 20°, indicating
a predominance of the anorthite-molecule. This is significant, as
the post-Carboniferous dolerites have usually a rather less basic
felspar, and generally show a second generation of a more acid
species, with zonary banding. In the rocks that I have examined
from this area, two generations of felspar are apparently not
present, and zonary banding is rarely exhibited. This fully agrees
with the characters shown by the felspars in the Bala diabases.

In proportion to the amount of crushing that the rocks have
undergone, characteristic changes are noticeable in the felspar, the
most striking of which are the secondary felspars, often conspi-
cuously present in large water-clear crystals, with ill-defined outlines,
and sometimes showing shadowy twin-structures. Where such
‘albitization ’ has taken place, the remnants of the older felspars
are easily distinguished by their extensive saussuritization, bent
outlines, corroded margins, undulose extinction, and by being often
included in the later secondary crystals. The secondary albites
also include epidote, viridite, and broken pyroxenes, while here and
there the characteristic ‘ felspar-mosaic’ of Lossen is exhibited. It
is difficult to measure the extinction-angles of these secondary
felspars, suitable crystallographic planes being wanting. In some
cases, however, it is possible to compare by Becke’s method the
refractive index of the felspar with that of an adjacent crystal of
secondary quartz. The result agrees with the refraction of albite.

All these characters are very typical of sheared diabases, and
indicate considerable pressure-metamorphism. Their importance
in the present discussion lies in the proof which they afford that
the rocks have been subjected to extensive earth-move-
ments. They are not, so far as I am aware, the characters
usually exhibited by the felspars of the later dykes of Caernarvon-
shire; neither does Mr. Harker mention them as occurring in the
Bala diabases. But the specimens described by him were apparently
not so much crushed, and were collected from areas more remote
from the Llyn-Padarn ridge.

The saussurite and other alteration-products of the felspar show
no unusual features. The large quantity of pale epidote and caicite-
dust is an additional evidence of a considerable lime-percentage ;
and all the phenomena go to show that the original magma was
of a typically-basic composition, and that the separating felspars
belonged to the lime-end of the albite-anorthite series. The original
composition of such a felspar, however, may be easily obscured by
secondary changes leading to the break-up of the anorthite-mole-
cules, and their replacement by epidote, calcite, and quartz. Such
changes may be traced along the course of these dykes, isolated
specimens of which, if taken from the crush-zone, would seldom
give an adequate clue to their original composition. As before

382 MR. J. V. ELSDEN ON THE AGE OF (Aug. 1904,

mentioned (p. 379), in certain of these crushed rocks secondary albite
has completely enclosed fragments of unaltered augite, causing a
total reversal of the original structure.

Pyroxenes.

It seems clear that there were two distinct generations of
pyroxene, causing an apparent deviation from the ordinary type of
the Bala diabases on the one hand, and from the post-Carboniferous
dykes on the other. It is true that Mr. Harker did find two
generations of pyroxene, in a rare instance near Llanrwst ; but im
the Llanberis dykes this occurrence is more frequent, although the
evidence is usually indirect, owing to the ease with which the
earlier form has yielded to processes of alteration, where it survived
the corrosive action of the magma. In a few instances, however,
comparatively-unaltered fragments of the earlier pyroxene are pre-
served as corroded remnants, included in the ophitic plates of the
second generation. More often these remnants are represented only
by rounded chloritic and serpentinous inclusions in the ophitic
augite. here is no sign of crystalline continuity of the two genera-
tions, and the circumstances seem to point to a complete change of
phase, the first-formed pyroxene being reabsorbed to a large extent
before the crystallization of the later variety, pointing to very slow
cooling, during which the conditions of equilibrium in the magma
underwent considerable change. The precise variety of the earlier
form is uncertain, but the fact that the included fragments are not
in crystalline orientation with the later variety would suggest the
possibility that the earlier forms were rhombic. In other similar
cases, such as the sahlite-diabase of Sweden,! the diabase of
Connecticut,? and in the Whin Sill,’ the earlier pyroxene is of a
paler colour and more easily altered than the later form. In any
case, the rounded serpentinous and chloritic inclusions in the ophitic
augites of Llanberis are more probably to be referred to an earlier
pyroxene than to olivine, as has been suggested by some observers.’

Coming now to the ophitic augites, there is evidence that during
their crystallization the magmatic conditions were not stable. Their
pale colour when fresh and the comparatively-low cy extinction-
angle indicate a variety near malacolite. They very commonly
possess the peculiarity (noticed also by Mr. Harker in the Lleyn
diabases) that the crystals, although apparently homogeneous, are
seen between crossed nicols to be polysomatic. ‘The separate areas
are crystographically continuous, but possess different extinction-
angles, This structure has been explained as a modification of the
hour-glass structure, for which the explanation of L. van Werveke”

' H. O. Hovey, Tschermak’s Min. u. Petr. Mitth. n.s. vol. xiii (1893) p. 218.

* J. 8. Diller, Bull. U.S. Geol. Surv. No. 150 (1898) p. 268.

3 J.J. H. Teall, Quart. Journ. Geol. Soe. vol. xl (1884) p. 653.

* A. Harker ‘ Bala Volcanic Series of Caernarvonshire ’ 1889, p. 94: see also
J. M. Clements ‘ The Crystal-Falls Lron-bearing District of Michigan’ Monogr.
U.S. Geol. Surv. xxxvi (1899) p. 201.

° * Beitrag zur Kenntniss der Limburgite’ Neues Jabrb. f. Min. 1879, p. 481.

Vol. 60.] THE LLYN-PADARN DYKES. 383

is often accepted. Neither this theory, however, nor that of Blum-
rich,’ seems quite adequate to account for the phenomenon, which
appears rather to be a modification of zonary banding, and points to
a sequence of different phases during the formation of the crystal,
owing to changes in the conditions of equilibrium. In some cases
the lines of separation of the different portions correspond to lines
of crystalline growth, indicating mere pauses in growth, the next
accretion consisting of a new member in the series of isomorphous
mixtures. Generally, however, there was more than a pause.
Resorption began; the salient angles of the last growth became
rounded off, and in some cases even greater corrosion took place,
before the crystalline growth was resumed in accordance with the
fresh conditions of equilibrium, which had, in the meantime, been
established. The difference in the extinction-angles of contiguous
areas reaches to as much as 10°, but is generally less. The
phenomenon is a very interesting illustration of the application of the
phase-rule in geology ; and if we accept Dr. Roozeboom’s explana-
tion of the formation of mix-crystals,? it is possible that we may
find in this structure a proof of consolidation under variable
pressure, such as might occur in the case of a magma cooling
under the influence of earth-movements. The same
structure has been noticed in the Holyhead Main Dyke and in the
olivine-dolerite of Port Newry,’ and I have also observed it in the
diabase of the Santon complex in the Isle of Man.

The chief difference observed in the augites of the crush-area is
the development of mylonitic structures, the ophitic plates being
broken up into fragments, round which secondary albite has
erystallized. The fragments, however, exhibit the same poly-
. somatic character, and have inclusions of the earlier pyroxenes as
described above. An intermediate condition, observed in some of
the specimens taken from the Llyn-Padarn ridge, near the southern
margin, has led to a very pronounced polysynthetic twinning in the
augites, often displaying two sets of twins crossing nearly at right
angles, and recalling similar strain-phenomena produced in metals.'
Such a difference in the effects of pressure upon the dykes enclosed
in the quartz-felsite and upon those in the sedimentary area is
very interesting, and resembles similar differences obtained
experimentally by Prof. F.D. Adams & Dr. J.T. Nicolson in marble
compressed under various conditions.°

Another effect of pressure-metamorphism, apparently related to
the above, is accompanied by a passage into amphiboles and
chlorites, to be described moré fully under these headings. |

I pass over the phenomena caused by simple weathering, as these
present no unusual features, and have no bearing upon the points
under discussion. I may, however, point out that this factor must

1 «Ueber die sogenannte Sanduhrform der Augite’ T'schermak’s Min, u.
Petr. Mitth. n. s, vol. xiii (1893) p. 239.

2 Zeitschr. f. physikal. Chem. vol. xxx (1899) p. 385.

3 Geol. Mag. 1888, pp. 269 et segg.
4 J. A. Ewing & W. Rosenhain, Phil. Trans. Roy. Soc. ser A, vol. exciii

(1900) p. 353.
° Ibid. vol. exev (1901) p. 363.

384 MR. J. ¥. ELSDEN ON THE AGE OF [ Aug. 1904,

not be lost sight of when utilizing the optical constants for the
determination of augites. For, even an incipient weathering may
lead toa change in the position of the optical axes. So far as I can
see in the specimens examined, weathering may produce (1) a
lowering of the cy extinction-angle; (2) a reduction in the value

eae see

of y—a; and (3) an increase in the value of - 3

Amphiboles.

In only a single instance have I found a small fragment of an
apparently-original hornblende, but secondary amphiboles are
represented in a large number of the specimens, more par-
ticularly in certain areas where the rocks have been subjected
to a particular kind or degree of pressure. Amphibolitization
commonly takes the form, in the first instance, of uralite-fringes
round the augites, thus bringing these rocks into close agreement
with the sills of the eastern part of Caernarvonshire, as described
by Mr. Harker; whereas the Lleyn diabases never exhibit this
structure. Uralitization is generally associated with pressure-
metamorphism,’ and it is difficult to escape from the conclusion
that the same pressure to which the uralitization of the eastern
sills was due also operated in the case of the Llanberis dykes.
That uralitization is independent of weathering processes pure and
simple seems abundantly clear, for the polarization-tints on the urali-
tized crystals are often high; while in the same slide, other crystals,
more weathered and showing lower tints, have no trace of uralite-
fringes. In partly-weathered crystals, also, uralite is equally well
developed on the freshest portion. It may, however, be mentioned
that the development of uralite is apparently checked wherever the
crystals have secured molecular relief from the effects of pressure,
either by the acquisition of strain-slip cleavage, or by mylonitiza-
tion. I do not know how far other observers have noticed this
feature, which is very well illustrated in these dykes, subjected as
they have been to varying kinds and degrees of stress.

More pronounced alteration of the augite leads to the develop-
ment of a pale actinolite and tremolite; and in some cases fissures
and cracks, varying from 3 to upwards of 2 inches in width, are
filled with tremolite or asbestos, which also coats shear-planes and
slickensided surfaces. Under the microscope, these features recall the
examples of ‘gewanderte hornblende’ described by E. Cohen,”
Bergt,’? and Doss.‘ The connection of asbestos with mechanical
movement in the containing rock has been already enlarged upon
by G. P. Merrill’ and Van der Bellen,° the latter maintaining that a
certain plastic elasticity is necessary for its formation. Direct passage
of augite into asbestos has been described by J. R. Blum‘; but in the

1 J. J. H. Teall ‘ British Petrography ’ 1888, p. 161.

2 Neues Jahrb. f. Min. vol. i (1883) p. 202.

* 'Tschermak’s Min. u. Petr. Mitth. n. s. vol. x (1889) p. 356.
* Ibid. vol. xi (1890) p. 46.

> Rep. U.S. Nat. Mus. (Smiths. Inst.) 1899, p. 296.

* Chemiker-Zeitung, vol. xxiv (1900) p. 284.

7 © Die Pseudomorphosen des Mineralreichs’ 1843, p. 165,

Vol. 60.] THE LLYN-PADARN DYKES, 385

present case it appears to be derived from uralite or tremolite, as
stated by Dr. Hintze.’ The exact nature of the change is at pre-
sent only a matter of supposition. It is not a paramorphic change,
since some hydration takes place; in fact, all the phenomena
connected with amphibolitization in general point to
the effects of dynamic metamorphism.

In connection with this portion of the argument, it may be well
to recall the observation of Prof. Grenville Cole & the late A. VY.
Jennings on the northern face of Mynydd-y-Gader,*? where the
intrusive diabase also shows a great deal of actinolite and tremolite,
with greenish asbestos in the clefts, pointing in their opinion to a
magma rich in alumina and lime, rather than to magnesia and iron.

The occurrence of asbestos in such quantity as is found in
some parts of the Llyn-Padarn dykes, notably along the Afon Goch
and on the western shore of the lake, near the mouth of the tunnel,
seems to me to have an important bearing upon the separation of
these intrusions from any eruptions of post-Carboniferous age in
this part of the country.

Biotite.

This mineral is very sparingly represented. Several of the less-
altered specimens contain a few shreds partly altered to chlorite.
In the crushed rocks no trace of it appears to be left. This fully
agrees with the character of the Bala sills, and it seems unnecessary
to dwell further upon this point.

Chlorite.

The chlorite-areas seen in these rocks have a well-marked
relation to the amount of shearing which they have undergone,
and are in inyerse proportion to the remaining augite. More
than one variety of the chlorite-family appears to be present, and
they present the following characters :—(1) green, radial, fibrous
scales, with parallel extinction and marked pleochroism, possibly
representing pennine or ripidolite; (2) granular aggregates ;
and (3) isotropic, structureless patches: these may be delessite and
chloropheite respectively. The first variety would, therefore,
belong to the true chlorites, and the two latter to the saponites
of Dr. Heddle’s classification.’ It is possible, however, that the
saponites are only more hydrated forms, and may be derived from
the chlorites by simple weathering processes. In the more highly-
sheared varieties the chlorites are drawn out into distinct lenticles,
showing a passage into flaser-diabase (the early stage of a chlorite-
schist) as has been already pointed out by previous observers, as
the result of the metamorphism of diabase by earth-stresses.*

1 Handbuch der Mineralogie, vol. ii (1897) p. 1195.

* Quart. Journ. Geol. Soe. vol. xlv (1889) p. 452.

3 Trans. Roy. Soc. Edin. vol. xxix (1880) p. 55.

* See J. J. H. Teall, Quart. Journ. Geol. Soe. vol. xli (1885) p. 183; T. G.
Bonney, iid. vol. xlix (1893) p. 94; T. G. Bonney & C. A. McMahon, ibid.
vol. xlvii (1891) p. 489; 8S. Hyland, Geol. Mag. 1890, p. 205; and F. Zirkel,
‘Lehrbuch der Petrographie’ 2nd ed. vol. ii (1893) p. 730.

Q.J.G.S. No. 239, sh

386 MR. J. V. ELSDEN ON THE AGE OF [ Aug. 1904,

Other Secondary Minerals.

An abundance of quartz, epidote, and calcite would be expected
to occur in rocks of this character. In the highly-sheared or
crushed rocks, as, for example, at Y Bigil, the quartz-grains have
almost the appearance of a clastic origin; but their secondary
character is proved by their sharp extinction when rotated between
crossed nicols. With regard to epidote, it may be mentioned that
Mr. Harker found this mineral to be restricted to the eastern portion
of Caernarvonshire. It is not certain, however, that we can regard
this mineral as a normal result of the pressure-metamorphism of
diabase. As might be expected, also, both quartz and epidote are
not confined to the dykes themselves, but have invaded cracks and
fissures in the neighbouring rocks. Very beautiful examples of these
quartz-epidote veins occur in the neighbourhood of the crush-area.
Calcite-eyes are everywhere abundant, and by weathering-out often
give the ‘ greenstones’ quite a vesicular appearance. It does not
seem necessary to dwell upon these phenomena, which are a direct
result of the mineralogical changes described in the foregoing pages.

General.

Summing up the above results, these rocks exhibit very varied
effects of dynamic metamorphism. In their least-altered parts the
minerals are comparatively unchanged, with the exception of
alterations produced by simple weathering. Coming nearer to the
crush-area, we find, first of all, the eftects of molecular re-
arrangement under pressure without movement. Then the influence
of shear begins to appear, with mylonitization and re-crystallization ;
and lastly the whole rock becomes more or less cataclastic, with
partial or complete obliteration of its original structure. It is not
generally possible to draw a sharp line of distinction between these
different phenomena, but viewed as a whole the results are suffi-
ciently characteristic. Moreover, the gradual appearance of these
features, as the dykes are traced from the quartz-felsite into the
sedimentary strata towards the east, is a proof that the deforming
agency operated from an easterly direction.

IV. Conciuston.

In view of the phenomena described in the foregoing pages, it does
not seem possible to escape from the conclusion that we have in the
Llyn-Padarn dykes a result of the deep-seated conditions prevailing
during the latest stage of the Bala eruptions. These dykes appear to
have been filled with a magma rather more basic than the Bala sills.
The mineralogical evidence seems to point to a larger proportion
of titanic acid, and toa greater amount of lime and magnesia. The
somewhat-remarkable chemical analysis by Dr. Veelcker,' of a rock

' Geol. Mag. 1868, p. 125.

Quart. JouRN. GeoL. Soc. VoL. LX, PL. XXX.

Benirose, Collo.

Photomicro, J. V. Elsden.

LLYN PADARN DYKE-ROCKS.

Vol. 60. | THE LLYN-PADARN DYKES. 387

from a ‘greenstone’-dyke in the Penrhyn Slate-Quarry, supports this

view ; but a large number of analyses of the Caernarvonshire rocks
would be necessary before Mr. Harker’s differentiation-theory could
be adequately tested on chemical grounds. ‘This theory is virtually
an application of Gouy & Chaperon’s principle,’ which, it is true,
receives some support from physical chemistry and from observa-
tions in the case of certain alloys.”

With regard to the exact time of the intrusions, it is certain that
the fissures were not open before the crush began, because there is very
little evidence of displacement in the dykes themselves. The Clegyr
dyke alone shows any marked sign of deflection. Mr. Harker,
however, mentions the occurrence of local thickening of some of the
dykes in the slate-quarries * owing to the effects of the thrust. It
might also be urged as an objection to the view that these fissures are
a result of the south-easterly crush, that their direction is approxi-
mately at right angles to the axes of the folds. Ina perfectly-
homogeneous rock, pressed by uniform forces against an immovable
buttress, the maximum shear should be at an angle of 45° to the
direction of thepressure. These conditions, however, did not exist.
The strata were not homogeneous, the pressure was probably by
no means uniform, and the buttress almost certainly yielded more
or less. It is therefore quite conceivable that the buttress cracked,
and thus determined the direction of the fissures in the sedimentary
strata.

The assumption that these dykes are of post-Carboniferous age
would involve two very unlikely conclusions: namely, that the later
magma was almost identical in its composition and in its mode
of consolidation with the basic injections of Bala age; and also
that earth-movements of sufficient intensity to cause structural
deformations of parts of these dykes have operated since the great
south-easterly crush which folded and cleaved the slate-rocks of
Llanberis. Of this there is no evidence, so far as I am aware; and
if such were the case, we should even then have to explain the
phenomena with which this paper chiefly deals, that is, that those
portions of the dykes which were protected by the ridge have
largely escaped the deformation to which their more easterly parts
have undoubtedly been exposed. On the other hand, all the facts
appear to agree with the suggestion that the Llyn-Padarn
fissures were injected with the last dregs of the Bala
magma before the effects of the post-Bala crush had
entirely ceased.

EXPLANATION OF PLATE XXXII.
[All the figures are magnified about 30 diameters. |

Fig. 1. Composite augite-crystal, showing crystallographic continuity, but
extinguishing in irregular areas. Crossed nicols: 1-inch objective.

«Sur la Concentration des Sear par la Pesanteur’ Ann. de Chimie
& de Physique, ser. 6, vol. xii (1887) p
> See A. Findlay “The Phase-Rule? 1902 chap. xiv.
3 ‘Bala Véloanie Series of Caernaryonshire’ 1889, p. 115.

388 THE AGE OF THE LLYN-PADARN DYKES. [Aug. 1904.

Fig. 2. Composite augite-crystal, similar to that seen in fig. 1, but showing
regular zones of crystalline ¢ growth. The section is parallel to the
orthopinacoid, and ther efore extinguishes simultaneously throughout.
Crossed nicols.

Augite-crystal showing secondary cleavage along glide-planes. Crossed
nicols.

4, Crushed diabase, showing secondary Palgpart enclosing broken frag-

ments of augite. Crossed nicols.

o. Sheared diabase, showing abundant development of epidote and chlorite.

Ordinary light.

(i, The same, showing feebly double-refracting granules, presumably

perowskite, enclosed in chlorite. Ordinary light.

CG:

DISCUSSION.

The Presipent, while admitting that many arguments might be
brought forward in favour of the post-Bala age of the movements
referred to, also saw difficulties in this view as to their age. Among
these was the smallness of the unconformity between Ordovician and
Silurian rocks in the area to the south-east of that described by the
Author; and the evidence of cleavage in the Wenlock Beds of the
Corwen district, comparable in many ways with that of the Cambrian
and Ordovician rocks of Caernarvonshire.

Prof. Warts pointed out that the dykes described by the Author
resembled in many respects the sill-rocks of Shropshire and Mont-
gomeryshire. These rocks were probably derived from the same
magma as the Bala lava-flows, but they were certainly intrusive
into the base of the Silurian of that district as well as into the
Ordovician, for the basal Silurian rocks were often metamorphosed
at the contact.

Mr. Frarnstpes said he thought that the rocks exhibited had
many features in common with the basic sills which occurred
among the Llandeilo and Bala rocks about Tremadoc. About
‘'remadoc many of the sills had come up along small thrust-planes,
and seemed to have baked rocks which, though already somewhat
crushed by the faulting, were still uncleaved. ‘This being so, the
sills at Tremadoc must be considerably newer than the Bala Beds,
and should be referred to the period of Silurian and post-Silurian
earth-movements rather than to the pre-Silurian.

The AurHor, in reply, said that, while he quite realized the
difficulty in assigning an exact age to the intrusions, he felt that
the greater the interval assumed to exist between the age of the
dykes and that of the sills, the more difficult became the explanation
of the facts adduced in the paper. The protective influence of the
Llyn-Padarn ridge, also, might be expected to become less marked
as the Cambrian sediments became more indurated, and it would
then prove less easy to account for the differential deformation of

the dykes.

—

Vol, 60.] GENESIS OF THE GOLD-DEPOSITS OF BARKERVILLE. 389

28. The Genusts of the Goip-Deposirs of BarkeRvILLE (British
Cotumpra) and the Vicrnity. By Austin J. R. Arkin, Esq.
(Communicated by the Secretary. Read April 27th, 1904.)

THe gold-bearing area of Cariboo is roughly confined within a
radius of 20 miles of Barkerville, to the band of varied crystalline
rocks known as the Cariboo Schists.

These rocks show evidences of fragmental origin, notably below
the mouth of Stouts Gulch. They represent in all probability the
silt and detrital matter deposited in a deep ocean lying off the
shores of the ancient Archean ridge, and are generally assigned
to the Lower Paleozoic age.’ They seem to have a tendency
towards fracture in a north-easterly direction, owing to pressure
exerted at right angles to their trend.

The steep northerly escarpments of the mountains are to be
attributed to the inclination of the beds, favouring the erosive
action of adjacent streams.

The whole schist-belt, with the exception of the mountain-tops,
is thickly covered with detritus of Glacial age and origin, which
obscures many features important to a thorough understanding of
the phenomena connected with the distribution of gold in this
district.

The quartz-veins, exposed in those places where Glacial débris
have not covered the original rocks, are all of one general type,
although two systems of fracture traverse the country. Most of
these fissures are infilled with veins, the richness of which has
contributed to the wealth of the placers below. The most striking
feature of a district in which the placers are so rich is that the
reefs at the heads of the gulches and along the sides
are of very low grade. ‘This has led to much speculation as to
the site of the original deposits from which the gold was derived.

The chief characteristics of the reefs of both systems are :—

(a) The veins follow the strike, but not as a rule the dip, of the enclosing
schists : an exception being the Forrest Reef on Proserpine Mountain.

(6) The gangue is similar to that found with the nuggets in the creeks—
lustreless, milky-white quartz, sometimes sugary.

(c) The mineralization is sulphide of iron, distributed in coarsely-crystalline
bunches throughout the reef. A little galena, low in silver, is sometimes
found; but rarely copper-pyrites, or blende. The average contents of
sulphide do not exceed 6 per cent.

Some of the sulphides are of good value, but others are quite worthless.
Their quality cannot be determined, except by assay. Galena has not been
found to exert any beneficial influence on the gold-values of the reefs.

(d) All the reefs show very little oxidized ore, some none at all: which goes

to show that the present outcrops are recent exposures, and cannot have
been the original surfaces presented on the tilting of the schist-bed.

1 The age of these rocks was determined by Mr. A. Bowman, of the Canadian
Geological Survey.

Q.J.G.S. No. 240. Qk

390 MR. A. J. R. ATKIN ON THE GENESIS [Nov. 1904,

The origin of the gold in the reefs is probably the same as the
origin of the reefs themselves. Both were deposited in fissures
formed by strains during the upheaval of the schists. There is
evidence that some of the veins are accretions formed in gradually-
widening fissures, and were not deposited in one gaping chasm.

This is especially apparent in the B.C. ledge, where thin films of
graphitic schist appear as partings in the vein on the hanging-wall
side, giving the reef a banded appearance. These may be taken
as part of the original wall which broke away with the early
accretions of silica, and became enveloped in the subsequent de-
positions as soon as the fissure widened again sufficiently for the
ascending waters to deposit a fresh crust of mineral salts. At
present, the parting on the hanging wall consists of a soft gangue
of frictional débris, among which the acid mine-water may still be
depositing mineral wealth.

These reefs, deposited by waters ascending from profound depths,
holding in solution their minerals dissolved under conditions of great
heat and pressure, would have a tendency to increased richness,
at the depth where the gradually-lessening conditions of their
solubility favoured the precipitation of mineral salts.

As most probably this rich zone is still intact, and awaits the
advent of deep-mining for its discovery, another source must be
looked for in trying to solve the problem of the occurrence of the
gold in the placers.

While all the reefs carry gold in greater or less quantities, none
have been found the richness of which would account for the placer-
gold; yet it is a well-known fact that rich outcrops exist in most
quartz-veins, unless removed by weathering of the enclosing rocks.
This greatly-enriched zone above the water-level must be con-
sidered as of purely-secondary origin: a concentration, in fact,
from the rock-masses of the reef above.

This concentration takes place in two ways. The first by
leaching of the pyrites, while the less soluble gold is left in the
honeycombed quartz, whereby the vein-matter is made lighter
while not reduced in bulk, which so becomes the richer per ton.
The second method is purely chemical, and is an actual enrichment
by precipitation.

The key to this secondary enrichment is found in the solubility
of gold in solutions of ferric sulphate, as pointed out by Le Conte
and Wurtz. The ores of these reefs are such that, on their decom-
position, quantities of this substance would be formed from the pyrites
present. While the pyrites furnishes the solvent for the gold, it acts
also as a precipitant for the same ; and the two processes of solution
and precipitation are going on at the same time, and are taking
place at the present day.

The area of the reef in which these forces come into play is
limited by the level of the circulating surface-waters, which remove
the dissolved gold and carry it down to a lower level, where, coming
into contact with undecomposed pyrites, it is again precipitated.
This process, going on continually—for although Nature works with

Vol. 60.] OF THE GOLD-DEPOSITS OF BARKERVILLE. 391

very dilute solutions, their volume is large and time is unlimited,—
in the course of ages produces a zone of great enrichment in the
neighbourhood of the permanent water-level.

The writer has seen specimens of gold showing the impress of the
pyrites upon which the gold had been precipitated, clearly proving
the order of deposition to have been, first, the pyrites in the reef,
and, secondly, the gold on the pyritic nodule.

While the enriched zone was being formed, the weathering of the
surface continually removed the leached outcrop and constantly
exposed fresh surfaces to the atmespheric influences : these, having
become more active than the solution and precipitation, in time
overtook the latter agencies and wore down the enclosing rocks
until what had been the permanent water-level became a very rich
outcrop.

To the weathering of such outcrops we may assign the rich
placers.

While the comparatively-recent removal has not left time for
another bonanza to be formed, it is only a matter of time when
the present exposed outcrops will become honeycombed gossans,
indicating rich zones below.

With the exception of the Perkins ledge on Burns Mountain, no
free-milling ore has been encountered which in any way adequately
accounts for the splendid placers of Williams’, Lowhee, Lightning,
Grouse, and many smaller creeks.

The gold found in all these placers is of purely-local origin, and,
being to a great extent associated with quartz, must have come from
reefs not far away. Indeed, some of the nuggets show no signs of
attrition, and would seem to have been derived from ledges in their
immediate vicinity. As no such ledge has been discovered in the
creek-bottoms, and any washing, such as a theory of transportation
from up stream requires, would have broken up the delicate
filaments of gold, some other explanation must be looked for to
account for these unwashed grains.

The most probable and satisfactory one is that these nuggets were
brought to their present place in a soluble matrix, and in the course
of time the matrix dissolving away left the gold in the condition in
which we now find it. This matrix was most probably calcite, as
nuggets have been found with limestone attached to them, and
many large beds of limestone traverse the schist-belt.

The origin of the quartz-bearing nuggets is easily accounted for
when we consider the conditions of the country in middle and later
Tertiary times. By the former date the hills now existing had been
swept clear of the pre-Tertiary gravels, and the deep channels
eroded to their present depth. After the hills had been exposed to
the action of frost and weather for many ages, the soft schists
were decomposed and gradually washed into the present creek-
bottoms, together with the gold set free from the rich surfaces of
the quartz-veins that we now see on the mountain-tops; and with
the gold from many others hidden under the Glacial and _ post-

Glacial gravels.
2E2

392 MR. A. J. R. ATKIN ON THE GENESIS | Nov. 1904,

Towards the end of Tertiary times a greatly-increased rainfall
took place, which washed the last remains of the decomposed
quartz-reefs and surrounding rocks into the valleys, together with
the last of the Tertiary gravels, which are at the present day
found associated with the gold in the lowest-known placers.

The present filled condition of these deep cuts is due to deposition
of material in later Glacial and Pleistocene times. In the open
workings of lower Williams’ Creek there is an interesting section
of these formations. Above the old drift-workings is a streak of
flat schist-pebbles, separated from the Tertiary gravels by a seam
of Glacial clay. This streak, about 2 feet thick, indicates a reces-
sion of the ice, and was deposited while Williams’ Creek brought
down the waters from the melting ice-caps on the surrounding
mountains, together with the rock-detritus from their sides.

It would be interesting to know whether this streak carried
much gold farther up. This would be likely, as the upper part of
the creek must have had very little gravel in it at this time, and so
would offer facilities for the gold being washed down on to the first
stratum of Glacial sediment. The auriferous upper streaks some-
times found along this creek are to be attributed to slight reces-
sions of the ice-cap: their limited extent showing merely a short
duration of the period when the creek was bringing down material
from its higher reaches.

Although, viewed in the above light, the occurrence of surface-
bonanzas is unlikely, it must not be forgotten that the reefs
which originated the placers still exist. Deeper exploration will
probably show an enriched zone deposited by the deep ascending
waters which gave the reefs birth, in no way connected with the
secondary enrichments which have made the placers famous, and
are in most gold-veins of doubtful continuity.

Discussion.

Mr. H. W. Moncxron asked whether goid had ever been found
in a calcite-reef.

Mr. Breprorp McNerit remarked that the paper was a very
interesting example of the generally-accepted theory of ‘ secondary
enrichment’ as applied to a particular ore-occurrence. Naturally,
one would have preferred to have visited the locality before dis-
cussing the paper. Our present views were mainly the outcome of
the comparatively-recent work of Posepny and others; but, given
low-grade auriferous iron-pyrites and given descending oxidizing
waters, there was no doubt that the chemical changes alluded to did
take place. In this connection, the experiments mentioned by Mr. T.
A. Rickard,’ as having heen commenced by Daintree in 1871 in
Dr. Percy’s laboratory at the Royal School of Mines, should not be
overlooked. A number of small bottles, each containing solution of
chloride of gold, were taken, and to each a crystal of the more common
metallic sulphides was added, such as pyrites, galena, blende, etc.

1 Trans. Am. Inst. Min. Eng. vol. xxii (1893) p. 313.

Vol. 60.] OF THE GOLD-DEPOSITS OF BARKERVILLE. 393

At the time when Daintree died, a few years later, no results could
be discovered; but one of the bottles was removed to Dr. Percy’s
private laboratory, and there in 1886, or 15 years after the
commencement of the experiment, a cluster of minute crystals
of gold was discovered upon the smooth surface of the iron-
pyrites.

In the case of the New Guston and adjacent mines in Colorado,
with which the speaker was connected some 12 years ago, the ore-
occurrence presented at that time many points of great obscurity,
but, as since pointed out by Emmons, Rickard, and others, if the
theory of secondary or zonal enrichment were applied, these diffi-
culties largely disappeared. As regarded the New Guston mine—
galena was most abundant from the surface down, say, to 300 feet,
the ore carrying 8 to 50 per cent. of lead, 9 to 30 ounces of silver
with a trace of gold. Ata depth of about 180 feet copper-pyrites
with stromeyerite came in, and continued down to about 700 feet,
the assays being : copper 5 to 15 per cent., 25 to 700 ounces of silver,
one-tenth to 3 ounces of gold. At about 600 feet solid bodies of iron-
pyrites were discovered, which continued to the deeper workings,
carrying | to 3 per cent. of copper, 4 to 20 ounces of silver, and two-
tenths of an ounce of gold. Bornite was met with between 700
and 1200 feet, carrying 18 to 25 per cent. of copper, 60 to 175 ounces
of silver, and a quarter to 14 ounces of gold. Free gold, which
was never seen above the 700-foot level or in any other instance,
was found associated with the bornite below the 700-foot level.
The workings were suspended at about 1500 feet.

With reference to the previous speaker’s remark, it might be
stated that calcite was not unknown as a matrix of gold; and
A. G. Lock had stated that most of the rich quartz-reefs at Gympie
(Queensland) contained abundance of calcite in strong veins and
patches, often richly impregnated with gold. A fine specimen from
these showed actual veins of fairly-large gold specks, irregularly
distributed through white opaque calcite.

394 MESSRS. BALDWIN AND SUTCLIFFE ON | Nov. 1904,

29. EHOSCORPIUS SPARTHENSIS, sp. nov., from the Mippie Coat-
Measures of Lancasnire, By Watrer Barpwiy, Esq., F.G.S.,
and Wrirt1am Henry Svrcrirre, Esq., F.G.S. (Read April
27th, 1904.)

ConrTENrs.
Page
I. Locality and Horizon of the Type-Specimen ............ 394
If. Description of the’ Type-Specimen -0y... ic. 7. + .c<cceuee-e 395
III. Comparison with other Species ................i.sceeeeeee 397
IV. Geological Bearing of the Discovery ....................- 398

I. Locatiry ann Horizon or THE T'yPE-SPECIMEN.

Ir reference be made to Sheet 88 of the Geological-Survey Map of
Great Britain, it will be seen that a portion of the Middle Coal-
Measures is repeatedly thrown in, between Rochdale and Heywood,
by several large faults, so as to form two isolated patches and two
large promontories jutting out northward from the general range of
the Middle Coal-Measures. About half a mile to the south-west
of Rochdale Town-Hall there is, at an elevation of 400 feet
above Ordnance-datum, an isolated eminence at Sparth Bottoms,
which is fast disappearing, as the shale is being excavated for the
purpose of making bricks.

This eminence is situated almost in the centre of one of the
before-mentioned promontories. At this point several beds of
greyish-blue shale, containing clay-ironstone nodules, crop out ;
and there is also a bed a few inches thick, with nodules containing
for the most part well-preserved remains of Carbonicola acuta.
These beds dip in a south-westerly direction. The Carbonicola-bed
may perhaps be taken as a fairly-constant horizon above the Royley
or Arley-Mine seam, since we have found it in Dawson’s Wood, about
a mile distant, and have calculated that it occurs about 135 feet
above the Royley-Mine coal-seam.

These beds have yielded remains of well-preserved ferns,
Calamariee,' Sigillarie,” and fine specimens of Merostomata, both
Prestwichia rotundata*® and Belinurus bellulus* have been found
here. A nodule which was found, in October of last year, about
8 feet above the Carbonicola-bed has added a new species to the
list of Carboniferous scorpions.

1 D. H. Scott, ‘Studies in Fossil Botany ’ 1900, p. 35.

* §. Sidney Platt, ‘ Fossil Trees found at Sparth Bottoms, Rochdale’ Trans.
Rochdale Lit. & Sci. Soe. vol. iii (1891-1892).

* Trans. Manch. Geol. Soe. vol. xxvii (1902) p. 149.

* Ibid. vol. xxvii i(1903) p. 198.

Vol. 60.] | ZOSCORPIUS SPARTHENSIS FROM LANCASHIRE. 395

II. Description or rae Typr-Specrmen. (Figs. 2 & 3, pp. 396-97.)

[Registered number in the Manchesier-Museum Collection L. 6271.]

The animal is well represented by both the intaglio and relievo
impressions on the re-

, (pasnsip ) soinsevay-[20D eIPPHAL spective halves of a
aoe Eg THERDE EST) clay-ironstone nodule,
5 Sil which is roughly cireu-

A lee cular in shape, unfor-

tunately showing the
dorsal and not the
ventral aspect of the
animal. We calculate
the length of the whole
animal(when extended),
from the anterior mar-
gin of the carapace to
the point of the tail-
sting, to have been
about 7+ millimetres.
Some portions appear
broader than they really
are, Owing to the spe-
cimen having been
crushed.
Cephalothorax.—
The carapace is sub-
quadrate in form,
shghtly narrower in
front than behind. We
are unable to make out
the character or position
of the eyes; nor can
more be said about the

4 oy
dy Coa

psodus saurotdes, ferns, Calamarice, ete.
, ferns, Calamarice, ete.

Shale

I
Natural Scale 3,700 or 300 feet to One Inch.

===] Sandstone

if the Coal-Measures at Spurth Bottoms (Lancashire).
g Eoscorpius sparthensis, sp. uov.

arbonicola acuta, Belinurus, Luphoberia

parth Bottoms Brickworks ~~;

Drab-coloured shale, with nodules containing Prestwichia. Stre

S ae :
2 3 carapace, owlng to its
= = crushed state.
S ae)
3 en © Appendages, —
‘<5 ‘Traces of the chelicerz
a ‘eS are observed, but are
uA S*5 insufficiently preserved
= wW . z= to admit of determina-
| re Ee tion. The left second
> D -
8 ne appendage is well pre-
* itt Served and is long,
3 slender, and chelate, and
yoy aay = mo xX ) ’
of: 8 free from tubercles.
Zz The hand is long and

ay slender (17 millimetres
in length by 4 in
breadth), and the biting-edge is free from denticulation. The

396 MESSRS. BALDWIN AND SUTCLIFFE ON [ Nov. 1904,

finger is, however, missing. Of the right second appendage, the
coxa only is preserved,

; 4 : : On the left side

Fig. 2.—Koscorpius sparthensis, sp. 0. —_ nortions of the second,

(Natural size.) third, and fourth legs

are preserved. The

fourth exhibits a

chelicera longitudinal crest,

and the segments
appear to be stout.

On the right side
the cox of the first,
second, third, and
fourth legs are clearly
seen, but the legs them-
selves are missing.

Pre-abdomen. —
The anterior seg-
ments of the _pre-
abdomen are short,
each succeeding seg-
ment gradually be-
coming longer, so
that the sixth as a4
little more than twice
the length of the
2, first. The dividing-
Pee line between the
We carapace and _ the

first segment is in-
[The shaded portion shows what is actually seen: determinate, because

chela}coxa of

sy

the dotted portion is restored. | of the crushing of this
portion.
MEASUREMENTS IN MILLIMETRES.
Length. Breadth.
Hirst see Mens \ os. se. ne: 2°5 (?) 10
Second segment ............ 30 1
Third seoment, 22.22.50 «sos: 30 11
Fourth segment ............ 4-0 12
Fifth segment ..............- 4°25, 12
Sixth segment’ J....).2..005< 4°25 12

These are all sub-ovate in shape, and have a smooth articular
border dividing them. The seventh is sub-trigonal in form, and
narrows so rapidly that its posterior border is only half of the breadth
of the anterior border, which is as broad as the posterior border of
the sixth segment. The anterior border is 8 millimetres in length,
the posterior border 4, while the segment is 5 millimetres long.
The whole surface of the animal appears almost smooth to the
naked eye, but when viewed through a lens it is seen to be granular,
with more pronounced granules on the seventh segment.

Vol. 60.] = ZOSCORPIUS SPARTHENSIS FROM LANCASHIRE. 397

A dark stain is observed next to the abdominal portion of the
animal, and probably represents the soft portions which have
been squeezed out by pressure.

Fig. 3.—Abdominal segments of Eoscorpius sparthensis, sp. nov.
(Enlarged 2 diameters. )

1 = First seginent of post-abdomen.
2 = Third segment of post-abdomen.
3 = Sixth and seventh segments of pre-abdomen.

The post-abdomen lies sideways, with the right side upper-
most. The dorsal and lateral keels are well marked on the first
four segments. Nearly all the segments seen are flattened. The
first is 5 millimetres long, 5 mm. broad, and shows a row of
granules on the left lateral keel. The second is 5 mm. long and
4mm. broad. The third and fourth segments are 6°5 mm. long
by 4 mm. in breadth respectively. The fifth segment is only partly
preserved, but may reasonably be inferred to ‘have resembled the
fourth. The tail-spine or sting is absent.

The following are some of the measurements of the specimen :—

Millimetres.
Greatest length of cephalothorax ..................... 10
Greatest breadth of cephalothorax ..................... 10
Total length of pre-abdomen ............... 0.022.605. 26
Greatest breadth of pre-abdomen ................... - 12
Total length of post-abdomen preserved ....... on th
Length of chela of second appendage ............... 18
Greatest width of chela of same ................+0-.. 4

III. CompaRisoN WITH OTHER SPECIES.

It is unfortunate that the carapace is not better preserved, so as
to show the median and lateral eyes, for these are the organs on
which generic classification proceeds. Although deprived of the
chief aids to generic distinction, the general form of the animal
leaves no doubt that it belongs either to Hoscorpius or to Eobuthus.

In appearance, it is almost identical with Lobuthus rakovni-
censis, Fr.,1 though in measurement it differs slightly from that
species. The whole animal is shorter, being about 74 millimetres
when extended, whereas Eobuthus rakovnicensis measures 75 mm.

' Fritsch, ‘ Palzeozoische Arachniden’ 1904, pp. 73, 74, & pl. xii.

398 MESSRS, BALDWIN AND SUTCLIFFE ON [ Nov. 1904,

on stone. ‘The pre-abdomen is shorter and narrower, while the
segments of the post-abdomen are each respectively shorter.

It is upon the length and breadth of the hand that we rely
principally for distinction, and this, too, we find to be slightly less
than that of HKobuthus rakovnicensis, which measures 19 mm. by 5.
The hand also is sufficient to distinguish it from Hoscorpius anglicus,
Woodward,’ /. glaber, or E. euglyptus.” It is longer than that of
i. glaber, and shorter than that of L. euglyptus, but is of almost
the same length as #. anglicus, although it differs in shape from any
of them. The remaining joint of the second appendage is devoid of
tubercles, and differs in this respect from the corresponding joint
of E. glaber or E. euglyptus.

The sculpture on the pre-abdominal segments of F. carbonarvus °
and Hy. tuberculatus * at once distinguishes them from this specimen.

What is preserved of the carapace is sufficient also to distinguish
it immediately from E. inflatus.’

Taken generally, the present specimen differs from all previously-
described Carboniferous species in possessing a more graceful form
and proportion.

At the suggestion of our colleague, Mr. W. A. Parker, of Rochdale
(who has devoted over 20 years to a study of the geology of the
district, and has very kindly brought the specimen before the writers’
notice), we have named the specimen Hoscorpius sparthensis,
the specific name being suggested by the place of its disinterment.

IV. GrotocicaL BEARING OF THE DISCOVERY.

In the eyes of geologists such a discovery has a special interest,
because it not only gives some slight indication of the zoological and
climatic conditions of this Palzeozoic land, but serves to mark roughly
the probable position of an old land-surface, since this scorpion 1s
too well preserved to have been borne far from its original habitat.
Dr. B. N. Peach, F.R.S8.,° writes :—

‘It may be that, as recent scorpions feed extensively on the eggs of various
invertebrates, the Silurian species also visited the shores for the eggs of animals
left bare by the tides, among which . . . the eggs of . . . the Eurypterids (if
the latter had the habits of their near relation, the recent king-crab) would form
a bonne bouche. If this suggestion should prove to be well founded, we
may suppose that it was this habit of frequenting the shores that led the present
specimens to be embedded in marine strata.’

The association of Hoscorpeus with the king-crabs in the beds at
Sparth Bottoms appears to prove that Dr. Peach’s suggestion is
well founded, and that the Carboniferous scorpions, hke the recent
ones, fed extensively on the eggs of various invertebrates.

‘ H. Woodward, Quart. Journ. Geol. Soc. vol. xxxii (1876) p. 58 & pl. viii.
~ B. N. Peach, Trans. Roy. Soc. Edin. vol. xxx (1882) pp. 400-402.

* Meek & Worthen, Geol. Surv. Llinois, vol. iii (1868) pp. 560-62.

' B. N. Peach, Trans. Roy. Soe. Edin. vol. xxx (1882) p. 398.

> Lbid. p. 408.

° * Ancient Air-breathers,’ in ‘ Nature’ vol. xxxi (1885) p. 298.

Vol. 60.] | #OSCORPIUS SPARTHENSIS FROM LANCASHIRE. 399

So interesting an addition to the numerous forms of arthropoda
from the Upper Carboniferous rocks of England deserves to be made
known as widely as possible, in order to stimulate a greater number
of geologists in the neighbourhood of coalfields to pay more attention
to splitting clay-ironstone nodules, by which means they may perhaps
increase our knowledge of the terrestrial air-breathing animals of
the Carboniferous Period.

In conclusion we should like to express our thanks to Dr. B. N.
Peach, F.R.S., for his kind examination of the scorpion; to Dr. A.
Smith Woodward, F.R.S., and Dr. F. A. Bather, whe allowed one
of us every facility to compare personally the specimen with
Eoscorpius anglicus and Eobuthus rakovnicensis in the British
Museum (Natural History); to Mr. R. I. Pocock, who gave much
valuable advice on the partial restoration of the animal; and to
Mr. 8.8. Platt, F.G.S., for particulars of the strata cut through
by the Sparth-Bottoms Colliery-shaft, which enabled us to show
more detail in the section (fig. 1, p. 395) than we otherwise could
have done.

Discussion,

Dr. Barner congratulated the Authors on their find of an
interesting and well-preserved fossil. He would be glad to hear
on what characters they relied for their statement that it was
distinctly a new species. The other fragments exhibited appeared
to belong to arthropods, possibly Merostomata.

Prof. P. F. Kenpatt, in adding his congratulations to those of the
previous speaker, complimented the Authors on the careful manner
in which they were working up these deposits, which were shown
to include three arthropod-horizons. Heasked whether the Authors
had studied the beds above the Arley-Mine seam in other localities,
and cited an exposure of beds of similar age in the Irwell Valley
where air-breathing arthropods had been found.

Mr. Batpwin thanked the Fellows, on Mr. Sutcliffe’s & his own
behalf, for the kind way in which they had received the paper.
In reply to Dr. Bather, he said that the Authors relied principally
on the dimensions of the hand and post-abdominal segments in
describing the scorpion as a new species. The new species, viewed
as a whole, was of a more graceful and slender build than any of
the other Carboniferous species. Replying to Prof. Kendall, he said
that the beds at Sparth Bottoms were the only beds in the district
that were being properly worked by the Authors, in which they had
found remains of arthropoda ; they had no doubt that at other places
on the same horizon arthropodan remains would be discovered, as
specimens of Merostomata had been obtained at Glodwick, near
Oldham. He was not aware that arthropoda had been found near
Bury, in Lancashire.

400 MR. G. BARROW ON THE MOINE GNEISSES _[ Nov. 1904,

30. On the Moinr Gwnetsses of the East-Centrat HigHianps and
theix Postrion m the Hiaatanp Seeuencre.' By Grorce
Barrow, Esq., F.G.8. (Read March 23rd, 1904.)

[Puates XXXIII-XXXVII.|

ConrTENTS.

Page

1. Introduetiony 5c. eet satte tee eee ee ee 400
IT, We. Mone :Giueisses: 5.4-. °5.22 1 Peete rt ee 400
ITI. Mode of Ending-off of the Moine Gneisses.................4+++ 415
LV” Appendix, 3 atc Batic asd eeaethe ack 2 eee eee eee eae 4492

I. Inrropvuction.

Tue object of this paper is: First, to describe the Moine Gneisses in
Perthshire and Aberdeenshire, and to show that in their mode of
occurrence and field-characters, as well as in their composition and
microscopic structures, they are identical with the Moine Gneisses of
the North-Western Highlands.

Secondly, to trace the mode of ending-off of these gneisses, and
to show that, while retaining their characteristic parallel banding
they pass into a smail zone of rocks, locally known as the
Honestones, which, in varying phases, lie persistently for miles
on the white margin of the Central-Highland Quartzite. The
parallel-banded Moine Gneisses are, in fact, simply
the flaggy margin of this Quartzite.

Thirdly, to phew, that in this special area, as the flaggy rocks
thicken, there is usually a small hiatus in the succession, owing
either to the contemporaneous erosion of the finer material that
should lie next them, or to its non-deposition. When this parallel-
banded material, however, attains a certain degree of fineness, this
erosion rarely occurs, and then the other limit of the group is the
Little Limestone. In fact, when the succession is complete, the
Moine Gneisses can be shown to pass laterally into the rocks of
the Honestone Group, and to lie between the white margin of the
Quartzite and the Little Limestone.

Whether these flaggy rocks lie above or below the Quartzite is at
present a matter of dispute. The view here taken is that they come
above the Quartzite, and the evidence for that view will be given
in detail.

The area examined extends from the River Garry, between Blair
Atholl and the summit of the Highland Railway, in a north-easterly
and easterly direction to Glen Girnoch, east of Balmoral in
Aberdeenshire, a distance of some 50 miles.

II. Tae More Gnetss&s.

The district over which the undoubted Moine Gneisses occur may
be divided into three parts: (a) the Struan area, which lies to the

* Communicated by permission of the Director of H.M. Geological Survey.

Vol. 60. ] OF THE EAST-CENTRAL HIGHLANDS. 401

west of the great Glen-Tilt igneous complex; (>) the area lying
between the Glen-Tilt complex and the great Cairngorm mass of
granite ; and (c) a tract which forms a small portion of the ground
to the south-east of the latter intrusion. ‘These masses of granite
are chosen to fix the position of the areas, simply because they are
shown on most small-scale geological maps, and are easily
recognized.

(a) The Moine Gneisses of the Struan Area.

This area is bounded on the west by the River Garry, and, as
the sections are easily accessible, it will be convenient to begin
with a description of the gneisses there exposed, and to use this as
a standard of reference in describing the gneisses elsewhere.

The Garry Section.—Since the days of McCulloch, the River
Garry above Struan has been famous for the sections of flag-like
rocks which are exposed in its bed and banks, from Struan, almost
without interruption, to the summit of the Highland Railway. Its
most striking feature is the extraordinary simulation of a normal
sequence of enormous thickness, the dip being apparently persistent
in one direction (the south-east), at an angle of from 20° to 30°.
As seen from a distance, almost the whole sequence consists of
well-bedded flags, the component bands varying in thickness, the
average of which is about 6 inches, or perhaps less. It will be
shown later that thicker bands predominate at one portion of the
series, and thinner at another.

The imitation of a sequence of enormous thickness, and the perfect
preservation of the parallel banding, together with their highly-
crystalline condition, enable these rocks to be easily identified.
Since the days of McCuiloch, many observers have noted the extra-
ordinary resemblance of the rocks to the flaggy gneisses of the North-
Western Highlands, now known as the Moine Gneisses. Further,
the mapping of the Highlands has progressed far enough to leave
no reasonable doubt that the Struan Flags and the Moine Gneisses
are one and the same group of rocks, and it is consequently
advisable to recognize this identity in describing them. Additional
facilities for their study have been afforded by the cuttings
recently made in widening the Highland Railway above Struan, by
means of which fresher material can now be obtained for
microscopic examination. (See figs. 2 & 3, pp. 404 & 405.)

The Grey Gneiss.—The dominant member of the Moine
Gneisses in this area is an evenly colour-banded and markedly-
granular, acid gneiss, containing a variable, but often considerable,
amount of brown mica. White mica is frequently present in
the typical gneiss, but as a rule in smaller quantity than brown,
while it is in many bands absent altogether. Though the amount of
brown mica varies incessantly, taking the group as a whole, it is for
the most part evenly distributed through small thicknesses of the
gneiss, varying from a fraction of an inch to sometimes as much as

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Vol. 60.] MOINE GNEISSES OF THE EAST-CENTRAL HIGHLANDS. 403

2 feet, or even more. This increase and decrease, in different bands,
of evenly-disseminated brown mica imparts different shades of grey,
pale-grey, or pinkish-grey to the banded gneiss, and is the principal
cause of the evenly colour-banded aspect, which is its most
characteristic feature. The bedded aspect of the series is often
intensified by the arrangement of the individual crystals of
biotite parallel to the colour-banding. But it is still further
accentuated by the presence of films of felted dark mica, which
are always rigidly parallel, and appear on a cross-fractured surface
as fine black lines.

These films decompose more readily than the rest of the rock,
and give rise to planes of diminished coherence, so that when
fragments become detached from a scar-face they break away along
those parallel surfaces. Further, this decomposed material weathers
out, leaving a series of minute paraliel grooves that have the
appearance of dark lines when seen from a distance of a few feet.
It is, indeed, to the presence of these films that the flaggy weather-
ing of the Moine Gneisses is essentially due; and when the gneisses
occur in thicker bands, or the films are much farther apart, the
flaggy character is partly lost. It will be shown later that the
presence of these films is of the utmost importance in tracing these
rocks when they thin away to the south-east.

That these rocks are altered sediments, and that the colour-banding
is coincident with the original bedding, is, in many cases, perfectly
clear from their chemical and mineralogical composition; but, if
any further proof were wanted, it is to be found in the small cross-
cleaved, highly-micaceous bands, originally more of the nature of
shales, that occur at intervals throughout the whole of the
Struan section. This cleavage of the original shale-material
obviously took place prior to any crystallization, and, as a rule, it
ends abruptly against the colour-banded rocks, which, frem their
present composition, must have been of a more sandy nature
originally, and would not cleave. The phenomenon is identical with
that observed so often in cleaved and folded Silurian rocks, although
the latter have not since been crystallized. Equally important, from
this point of view, is the occurrence in the deep cutting at the
Perth 42-milepost of a special type of grey gneiss, in which there
is scarcely any parallel banding; even the parallel arrangement of
the biotite in the rock is not well marked, and the felted films of
biotite are entirely absent. This rock differs from the more common
type of gneiss in its mode of weathering, and on open ground forms
rounded blocks of massive aspect, somewhat resembling a very fine
granite. The absence of any indication of the original bedding
suggests that the material was deposited under somewhat different
conditions from those of the parallel-banded gneisses. It may be
here noted that no thick band of such material ever oceurs near
the south-eastern margin of the Moine Gneisses, or in the ground
where they end off.

It may not be out of place, in concluding this account of the
macroscopic character of these gneisses, to draw attention to the

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Fig. 3.—Typical scar formed of Moine G'neisses, showing the resemblance
to unaltered sandstones : on the River Garry, near Clune, 2 miles

north-west of Struan.

Q.J.G.8. No. 240. 2F

406 MR. G. BARROW ON THE MOINE GNEISSES ___[ Nov. 1904,

fact that their highly-crystalline character is shown, not by the
quartz or felspar, but by the persistently-large size of the micas,
when these are present in notable quantity. Years of study have
proved that this is by far the most sensitive test by which to judge
of the degree of crystallization in altered sediments, such as were
originally normal sandstones and shales.

Microscopic Characters of the Gneisses in the Struan
Area.—Great light is thrown on the structure and composition of
these gneisses by the aid of the microscope. ‘Taking first the
prevalent type—the parallel-banded rocks, we find that they
are essentially felspathic gneisses, the felspar being usually in excess
of the quartz, and in some cases occurring almost to the exclusion of
the latter. As the quartz decreases in amount it tends to assume a
rather rounded form, embedded more or less in the felspar, and con-
stituting ‘quartz-bleb structure.’ It may, when present in very small
quantity, occur as minute globules in the felspar, imitating exactly
the micropoikilitic structure of igneous rocks. The felspar is of two
kinds— microcline, for the most part fresh and showing the typical
cross-hatching; and plagioclase, usually much decomposed. It is
almost impossible, in many cases, to be certain of the nature of the
plagioclase-felspar, but in some instances it is clearly oligoclase.
The relative proportion of microcline to plagioclase in the gneisses
of the Struan area varies greatly. In the lighter-grey varieties
plagioclase seems to be, as a rule, slightly in excess ; in the darker-
grey varieties, microcline often exceeds the other in amount. When
the gneiss weathers with a distinctly-pink edge, the microcline seems.
usually to be the dominant felspar in this area; and it is, at
times, more abundant than plagioclase aud quartz taken together.
A good idea of the general structure may be obtained by selecting
a specimen in which the quartz, microcline, and plagioclase are
present in nearly-equal proportions.’ It will be seen that the
grains are, on the whole, evenly distributed, as if they had been
first mixed in a pepper-pot and then shaken out. This granular
arrangement of the component grains may be described as a
‘granulitic structure*; but it cannot be too clearly understood
that it is unlike the granulitic structure of many of the schists
of the Southern Highlands. The microcline usually retains this
granular mode of occurrence, even when present in large quantity,
and it rarely helps to bring out the foliated character or parallel
structure of the rocks. But, if the plagioclase increases in pro-
portion, it assumes irregular forms, and tends to occur in much
larger and often elongated patches that help to define the parallel
structure. The quartz in the latter case frequently appears
embedded as ‘ blebs’ in the felspar, a mode of occurrence that can
often be made out by the aid of a hand-lens.

The foliated aspect, in hand-specimens, of a single band or flag

' See Pl. XXXTV, fig. 1 (No. 88). The low numbers refer to photographs in
the possession of the Geological Survey; the high ones (10,422) to the micro-
scopic rock-sections,

Vol. 60. | OF THE EAST-CENTRAL HIGHLANDS, 407

of the gneiss is mainly due to the parallel arrangement of the
micas ; and microscopic sections show that, as a rule, these are so set
in the rock as to interfere only to a small extent with the granular
structure shown by the quartz and felspar. It is only when mica
is present in sufficiently-large quantity to impart an almost-tissile
character to the rock, that its influence appears in the rock-
structure. In that case, almost continuous films of biotite or biotite
and muscovite separate well-defined parallel strips of quartz-felspar
material. The edges of the grains in contact with the mica are now
distinctly flattened, and, moreover, the grains within the parallel
strips tend to assume a somewhat quadrangular form (Nos. 85, 89,
& 9V).

ae Struan and adjacent areas, the biotite of the Moine Gneisses,
when fresh, is always of the normal haughtonite-type—that is,
when seen in cross-section and rotated under a single nicol, it
changes in colour from brown to a watery-black. Inclusions with
more or less pleochroic halos occur in the biotite, although they are
not a marked feature of the mineral. Chlorite is present in many
of the rocks, more particularly in the micaceous gneisses. It is very
difficult to say whether this is a replacement-product after brown
mica or not. It is too often forgotten that lime, though in small
quantity, is an essential constituent of normal biotite; and, in many
cases, the more or less chloritic original material from which these
rocks were produced did not contain sufficient lime to form even
biotite when metamorphosed, and then the chlorite is the direct
product of thermal metamorphism. Pleochroic spots are common
in this chlorite. The white mica presents no feature of importance,
except in its mode of occurrence. It does not conform to the
foliation so closely as the biotite, and in some of the rocks it is set
with the basal plane at right angles to the foliation.

In addition to the minerals just enumerated, small crystals of
sphene are common in some of the specimens, and present in almost
all. They are often pointed, elliptical in shape, and are frequently
coated with a film of iron-oxide. They have usually the aspect of
metamorphic sphene, and are never strictly original. Apatite occurs
occasionally, as also zircon. The latter is not nearly so common
as might have been expected in such rocks, which clearly originated
from fine felspathic and micaceous sands. Small garnets occur in
certain dark blotches in one band of very pale gneiss, but the
mineral is not common in this area.

Taking the grey gneisses as a whole, they are remarkable for the
amount of microcline present, and, in this respect, they differ from
the grey gneisses of the areas farther to the north-east (to be
described later), where microcline is less common, despite the close
external resemblance between the rocks in the two areas.

The Pink-edged Gueisses.—In addition to the dominant
grey-banded gneisses, there are also present some that weather with
a pink edge, even though they are grey on a freshly-fractured face.
These pink-edged varieties are especially interesting, because they

2F2

408 MR. G. BARROW ON THE MOINE GNEISSES [| Nov. 1904,

serve, more than any other members, to correlate the Moine Gneisses
of different areas despite local variations of character. It has
been found in the Struan and adjacent areas that these rocks
are especially rich in microcline. Moreover, when the pink colora-
tion is well marked, they asually contain in addition some calec-
silicate, which is most commonly epidote or zoisite, but at times
hornblende is present. Typical examples of the epidote-bearing
variety are abundant in the second cutting above Struan Railway-
station. ‘The most interesting example of this pink type, however,
occurs in the bed of the Garry, immediately in front of Dalnacardoch
Lodge. Like all the rocks close by, it splits into comparatively-thin
slabs, owing to the presence, at short intervals, of the thin films of
felted biotite already mentioned. Between these films the rock 1s
not particularly fissile; indeed, it is rather tough, and shows a
mottled red-and-green coloration, on a cross-fractured surface. A
section shows that it is composed mainly of the typical cross-hatched
microcline. This forms a kind of groundmass, in which are set a
number of aggregates of green mica, the long axes of which are
parallel to, and, indeed, serve to mark, the foliation of the rock.
A small amount of plagioclase (in irregular patches) and a little
white mica are also present. Apatite is fairly common, and occurs
in much the same manner as the quartz. ‘This latter mineral is
present in very small quantity, and most of it is found as tiny blebs
in the microcline, affording a perfect example of micropoikilitic
structure. The occurrence of this rock, so rich in alkali-felspar, is
especially interesting, as it tends to recur again and again over a
very large area, and apparently at a definite horizon.’

The highly-micaceous Gneisses.—These rocks are charac-
terized by abundant white mica and biotite or chlorite. For the
most part they are cross-cleaved, as already stated ; but where only
a very thin parting occurs, the gneiss is at times ‘ rodded,’ that is,
the micas are all elongated in a definite direction, and there is no
specialiy-marked plane of schistosity. This variety serves to show
that the originally-softer parts of the series have often suffered
considerably from dynamic action prior to crystallization.

These micaceous bands possess a somewhat different structure
from that of the other gneisses. In the cross-cleaved variety there
is a tendency to form lenticles, free from mica, as in the true
schists, but the lenticular structure visible in the hand-specimen is
not nearly so obvious under the microscope. Comparatively-little
microcline is present, and only a moderate amount of felspar.
Quartz, on the other hand, is more abundant than would have been
suspected. Apatite is much more common than in the parallel-
banded rocks. The abundance of quartz explains, what is specially
noticeable, the total absence from the micaceous gneisses of silicates
of alumina, such as sillimanite, cordierite, andalusite, etc. Clearly,

' See Pl. XXXVI, fig. 1 (No. 84). Further investigation has shown that
this is the ‘ Pink Felspathic’ rock described on p. 416, and marks the top of
the Moine Gneisses.

Vol. 60.] OF THE EAST-CENTRAL HIGHLANDS, 409

after the formation of the micas, there was not an excess of alumina
sufficient to form such minerals, and the microscope confirms the
inference that the shale was originally somewhat gritty and impure.

Other Exposures in the Struan District.

The flaggy gneisses just described cover a large area on both sides
of the Garry, above Struan. On the open ground, however, good
exposures of them are not numerous, because the flanks of the hills
are much obscured by Drift, and the crests of the hills are frequently
covered by a somewhat angular rubble, which is due to the dis-
integration of the rocks. About the Dalnacardoch area, and for
some distance eastward, the massive grey gneiss is especially
abundant, where it weathers in the form of rounded blocks.
Owing to its greater power of resisting decomposition, it is often
seen in situ. Excellent sections are exposed, however, in the
streams that drain into the Garry, and these are often continuous
for considerable distances. Microscopic examination shows little
variation in the type-rocks ; while the appearance of a continuous
dip is at times even more marked than in the Garry section.

In the area between Struan and Blair Atholl, the gneisses undergo
a slight change, becoming, on the whole, more micaceous, and in
many cases rather more fissile. The latter character is shown by
microscopic sections to be due to the parallel arrangement of the
white mica, as well as of the brown, the two being often in contact.
Good examples of this type occur in the cutting near the Manse,
north-west of Blair Atholl, where the rocks appear to contain rather
less microcline than usual. Around the igneous complex of Glen
Banvie, and for some distance to the south-east, the gneisses are
rather more quartzose than usual, becoming at times almost quartzites.
A typical example of the latter is essentially a granular mosaic of
quartz and felspar, with a little brown and white mica, but it differs
from the Central-Highland Quartzite in the large amount of micro-
cline present. Farther down the Banyie Burn greyer-banded types
occur, well shown in the quarry under the road at the western end
of the Whim Plantation. One of these (10,422) contains many oval
crystals of microcline, within which are numerous poikilitic grains
of quartz, as well as minute flakes of mica and grains of garnet and
epidote. Most of the grey bands, with parallel biotite, contain
much microcline, but when the biotite is abundant it begins to show
a reddish-brown tint. <A little band (10,424) having much the
appearance of the material that forms the more massive rocks about
Dalnacardoch, is also seen here; and it is especially worthy of note
that this contains hardly any microcline, but much plagioclase in
sheets enveloping the quartz.

Before leaving the Garry area, attention may be drawn to two
special rocks. The first occurs in the river-bed at Dalnacardoch, and
has already been described (p. 408); the second is associated with
the typical grey-banded gneiss, and is composed of white quartzose-
looking material, within which are set a number of dark blotches

+10 MR. G. BARROW ON THE MOINE GNEISSES {| Noy. 1904,

The latter was first seen in the railway-cutting below the Perth 42-
milepost, and later on at the Perth -t4-milepost. Mr. Macconochie
found it in the bed of the river at Struan and in a number of other
places, but it does not seem to be associated with the more massive
gneiss. This band, which we propose to call the ‘ Blotch-Rock,’
can be immediately recognized; indeed it has .been met with
over a large area, and serves toshow more than anything else that
the rocks composing the colour-banded gneisses were originally
quite thin.

Area north of Struan, about the watershed of
Perth ana Inverness.

As we approach the watershed, the south-easterly dip slowly
changes, and becomes northerly. In the Gaick Burn, although the
typical grey gneiss is present, most of the bands are thin, and of
the type of those seen at Dalnacardoch. Three varieties of these
thinner bands are worthy of special notice. One is akind of spangled
gneiss, and contains a considerable amount of biotite, and at times a
few crystals of muscovite at right angles to the banding (11,055).
From its mode of occurrence, we may assume that it was almost
certainly a shaly rock originally, but its dominant constituent now
is well-crystallized microcline, which forms 60 per cent. of the rock.
There can be little doubt that this microcline in such a rock
results mainly from the action of finely-divided micaceous material
on finely-divided quartz, thereby forming microcline ; for it will be
seen later that this excessive amount of microcline, in many cases,
characterizes the limestone and the adjacent shales. A specimen,
on the other hand, with much white mica contains little alkali-
felspar, suggesting that in this case no such interaction took place
(11,058). Associated with these, is a little band containing epidote
along certain lines. But one of the most striking features of the
exposures about the Gaick Burn is the frequent repetition of the
little ‘ Blotch-Rock,’ showing that over a large area we do not move
more than a few feet from one horizon in the original sequence.

Near the watershed the more thinly-banded rocks slowly dis-
appear, and the normal grey gneiss is again met with. The most
abundant phase (11,052) is rather light-grey in colour, with quartz-
grains, somewhat rounded ‘quartz-blebs’ set in a matrix of felspar,
most of which is the typical microcline (97). Some plagioclase is
present, mostly decomposed. A somewhat darker phase (11,053)
contains slightly less microcline, with more quartz, and in this the

‘quartz-bleb’ structure is not so well shown. In both, the mica
shows the usual parallel arrangement ; the typical small sphenes
are fairly abundant, while minute zircons are more numerous than
in most of the specimens from the Garry area.

(b) Area East of the Glen-Tilt Igneous Complex.

In the Perthshire portion of the area east of the Glen-Tilt
complex, several important differences in the Moine Gneisses are

Vol. 60. | OF THE EAST-CENTRAL HIGHLANDS. 4th]

visible, as compared with those already described ; and, in addition,
small outcrops of other members of the succession are met with, by
the aid of which the position of the parallel-banded gneisses can be
fixed. A distinct, though slight, change in composition is shown
by the increase of biotite in the rocks as a whole; and this is
accompanied by the development of sillimanite in some of the more
micaceous thin partings, thereby fixing the phase of crystallization.
Obviously, the original material had become more muddy on the
whole, and less of a fine arkose or sand, though the latter character
was still retained in one part of the group.

Two types of the gneiss in this area are worthy of special notice.
The first weathers with rounded outlines, is of somewhat massive
aspect, and resembles a fine granite. It forms the long, rounded
ridge stretching from An Sgarsoch, at the county-boundary, in a
southerly direction to Sron na Macranach, on the north side of the
Tarf. Considerable masses of similar rock occur on Cairn Fidhleir,
farther west. This tract lies in a line with the other outcrops of
the massive, round-weathering gneiss already mentioned, of which
it seems to be a slight modification. Sections of these rocks show
that they contain singularly-little microcline and an unusual amount
of plagioclase (mostly oligoclase), often fringed with vermicular
pegmatite, and at times partly idiomorphic with respect to the quartz
(11,059).’ In both localities, the round-weathering type of gneiss
is succeeded by a singularly-flaggy phase, in which microcline is
abundant and parallel structures are well marked: thus strongly
suggesting that the rock so rich in plagioclase marks a distinct
horizon. As in the Struan area, thin bands of somewhat similar
material occur to the south-east: and in these the plagioclase has
frequently much vermicular pegmatite on its margin, forming
clubbed ends to the narrow crystals (11,066).

The second type of gneiss of special importance in this area is
sharply separated from the normal phases hitherto described by the
occurrence within the individual bands of a lenticular or ‘ thrust-
plane’ structure, similar to that met with in the grits of the Southern-
Highland border, and due to mechanical deformation. <A typical
specimen (11,076) is a grey gneiss with thrust-plane structure, in
which the movement-planes are coated with dark mica. It is
composed of abundant oligoclase and quartz occurring together in
lenticles, separated by films rich in reddish-brown mica. These
films alternately approach and recede from each other, and show
the typical undulatory parallelism of a true schist of the Southern-
Highland type. The occurrence of this structure is highly im-
portant, as it shows that when the material of the Moine Gneiss
was strongly affected by dynamic action, the rocks crystallized as
typical lenticular or phacoidal schists. It is a fair inference, that
the persistent absence of any such structure from the typical grey
gneisses is conclusive evidence that they suffered practically no
mechanical deformation prior to crystallization within the individua]

1 See Pl. XXXV, fig. 2 (No. 107).

412 MR. G. BARROW ON THE MOINE GNEISsES | Nov. 1904,

bands, though considerable sliding may have taken place along the
greasy chloritic parting-films. The belt within which this structure
occurs commences at the Tilt Valley, on both sides of the Tarf,
and stretches to the foot of Sron na Macranach. It. will be
described in detail in-the Survey memoir on the district. |

Aberdeenshire Area, west of the Lochnagar Granite.

The feature of this area, on the whole, is the perfection with
which the parallel structure is shown in the field, especially in
stream-sections; the bands are perhaps thicker than in the Garry
area, and they have a singularly-massive habit, owing to which
they may be described as of the ‘ massive-pavement’ type. These
massive pavements are admirably shown in the bed of the Geldie
above its junction with the Dee, where the river runs approximately
parallel with the strike. The dominant type of gneiss is grey, and
highly crystalline. Granulite and quartz-bleb structures are common
in many of the rocks, and they contain, on the whole, little white
mica. The biotite varies: sometimes it is normal haughtonite, but
more often it is of the reddish-brown type. Garnet occurs in micro-
scopic sections more frequently than the external appearance of the
rocks would lead one to expect. Plagioclase-felspar is far more
abundant than microcline, though here again there is one horizon
at which the latter is fairly abundant. Three types are worthy of
special reference. The first is a banded grey gneiss (8512), in which
Dr. Teall noted a line specially rich in iron-ore and zircon, clearly
indicative of original bedding and parallel to the colour-banding ;
it is a typical granulite, with no trace of quartz-bleb structure.
The second is remarkable for the number of small pink garnets in
it, which enable the band to be easily identified (8510). Like the
‘ Blotch-Rock’ of the Struan area, this ttle garnet-band has been
met with again and again over the area west of the Cairngorm
Granite, thus indicating that the whole group was originally of no
great thickness. The third type is a pink-edged epidotic gneiss
containing much microcline, which, though present over a limited
area, 1s abundant close to the margin of the granite, and specially
so near Monadh Mor, just inside the boundary of Inverness-shire.
A typical specimen (8519) is almost identical with (8518) from
the Allt Unich, south of the Geldie, which, on account of its
linportance, will be referred to again (see p. 436).

Area flanking the Dee above Braemar.

In and about the Allt Unich, just mentioned, a considerable
portion of the Moine Gneisses is highly quartzose, and differs
markedly trom the typical grey- and pink-banded rocks, which are
here present only in subordinate quantity. This is due to the fact
that the flaggy gneisses are here largely composed of the Central-
Highland Quartzite, exhibiting many of the curious structures so
characteristic of the Moine Gneisses. Although these quartzose
rocks possess a flaggy aspect on the whole, it is not so marked as in

Vol. 60. | OF THE EAST-CENTRAL HIGHLANDS. 413

the parallel-banded grey gneisses ; for the typical highly-chloritic
films of the latter were never present in the original quartzite. On
the splitting-face a thin film of fine, evenly-disseminated muscovite
is present, which gives rise to the flaggy aspect of the quartzose
gneiss. It was doubtless developed along buckling-planes from the
felspar in the Quartzite. This type of material is the dominant
constituent of the Moine Gneiss on the south side of the Dee, for a
considerable distance to the east.

Approaching Braemar, the colour-banded pink-and-grey rocks
increase once more in amount; but still, in small openings by the
roadside, portions of the true quartzite can be identified, despite the
new structure developed in it, by certain fine dark lines of heavy
minerals, to which special reference will be made in describing the
-Quartzite.

(c) Area south-east of the Cairngorm Granite.

In that portion of Invercauld Forest which les between the
Sluggan Burn and the ridge of Cairn Liath to the east, the Moine
Gneisses vary somewhat in appearance. Highly-quartzose rocks are
more abundant in the south-eastern part of this ground, and the
bands are distinctly thinner; but farther to the north-west they
thicken and, on the whole, become more felspathic and variable in
composition. Where thinner, they consist essentially of three small
bands: the first being practically quartzite, the second darker with
more brown mica, and the third a kind of pink-edged quartzite.
These three thin bands, by repeated foldings on themselves, form
great rock-masses, which can be admirably studied in the low crags
alongside the Sluggan-Burn footpath, at about a mile above the
junction with the Dee.’

A little to the south-east of these crags, it is again often
impossible to say where the Moine Gneisses end off and the Central-
Highland Quartzite begins; for the latter now occurs in a ‘ Moine-
phase.’ The typical white margin of the latter can be identified on
the tootpath above the house, near the northern end of the plan-
tations; and, starting from this point, it is clear that the greater
part of the quartzose gneiss must be formed of the Main Quartzite.

On the ridge between Meall Gorm and Cairn Liath, little but the
three quartzose bands already mentioned can be seen. The palest
band is met with first, and is just sufficiently banded to be separable
from the true Quartzite. Farther north the greyer band appears,
slowly becoming more felspathic and more like the typical grey
gneiss. On the southern part of Cairn Liath, the pink quartzose
band is the dominant rock, and must be folded on itself to an extent
that is almost incredible, to form so large a portion of this hill.
Farther west, the thickening and the change in composition are soon
well marked: the pink-edged rock in particular having darker and
more felspathic bands in it. One of these has a rather mottled

1 See p. 435 for a description of these bands where the Moine structure is
not developed.

414 MR. G. BARROW ON THE MOINE GNEISSES _—_[ Nov. 1904,

aspect, and possesses the typical granular structure of a Moine
Gneiss ; it is composed of both potash- and plagioclase-felspar, which
together exceed the quartz in amount. Biotite is fairly abun-
dant, and epidote occurs along certain lines. This is the typical
pink-edged epidotic gneiss, which occurs over a wide area. Still
farther west, both angular and round-weathering grey bands
appear; but the pink-edged rocks still predominate, always con-
taining a considerable amount of potash-felspar, the latter often
fringed with vermicular pegmatite. Closer to the head of the
Sluggan Burn, infolds of more highly-quartzose rock are met with,
and increase in size, until the large mass separated-out on the map
is reached, which is once more, in the main, the Central-Highland
Quartzite, with the Moine-Gneiss structure superimposed on it.

On the south side of the Dee, to the east of Braemar, the old
difficulty recurs in separating the true Quartzite from the highly-
quartzose Moine Gneiss; but a faint remnant of the typical,
parailel-banded, grey material is seen in the little quarry, close
to the gate of the footpath that passes on the south side of Creag
Choinnich.

One of the few cases in which the Quartzite in a ‘ Moine-phase ’
can be separated from the quartzose gneiss is met with on the hill-
top above Balloch Farm, some 2 miles north-east of Invercauld ;
the latter being seen practically in contact with the white margin
of the former. The best locality for studying this is between the
limestone and the small mass of diorite and granite,’ farther west.

Summary.

This account of the Moine Gneisses may be summed up briefly as
follows :—

1. These gneisses are a parallel-banded series of sedimentary
origin, usually rich in felspar (largely microcline), and con-
taining dark biotite in variable quantity.

2. The gneisses are thinly-bedded, as a whole ; and their structure
is essentially parallel, but not lenticular or phacoidal. This
parallel structure is in most cases shown by the arrangement
of the biotite.

. Certain types can be recognized again and again throughout
the whole area; and their repeated occurrence shows that
the whole series is really thin, although by intense folding
it simulates a succession of enormous thickness.

4. Although the variation in the typical grey gneisses, as they
are traced eastward, is not great, still it is important.
Biotite is, on the whole, more abundant; and the highly-
micaceous partings become more aluminous, that is, were
more of the nature of fine mud originally.

5. A striking feature of the grey gneisses is seen in the films
of felted biotite, derived from original clastic chlorite, and

Se)

_ | The position of these rocks is shown on the Geological-Survey 1-inch map,
Sheet 65, to be published shortly.

Vol. 60. | OF THE EAST-CENTRAL HIGHLANDS. 415

indicating the former bedding-planes. Their presence is
highly important, especially when we consider the mode
in which the Moine Gneisses end off when traced to the
south-east, as it will be seen that they link the gneisses
with the Dark Schist, of which the same material was an
abundant constituent.

6. Lastly, a considerable mass of highly-quartzose material, which,
for purposes of mapping, must be included in the Moine
Gneiss, can in the eastern part of the area be shown to be
really the Highland Quartzite (in what may be conveniently
called a ‘ Moine-phase’), and should be excluded from the
group in discussing the origin of the grey gneisses.

III. Move or Enpinc-orr oF THE MoINE GNEISSES.

Having shown that these gneisses extend in a south-easterly
direction to the Tilt Valley, the Geldie, and the Dee, almost to
Braemar, we may pass on to consider the question why they do not
appear in their typical phases to the south-east of this long line.
The simplest explanation would be that they have been faulted-out ;
and in the Glen-Tilt area this, at first, seems to be the true one.
That it is not sufficient, however, is clear from the fact that in some
cases the gneisses cease to be recognizable before the main fault is
reached, while in the district east of the Geldie they cross the fault
in mass. Two other causes may be suggested: first, that they become
less crystalline, and so cease to be recognizable as Moine Gneisses ;
or, secondly, that they thin away. It will be shown that both
causes co-operate to render the further tracing of them a matter of
difficulty.

(a) The Belt of Decreasing Crystallization.

The first of the causes above suggested is most important in the
Tilt Valley, where the decrease in crystallization is unusually
rapid. It occurs along a belt that has been traced from the coast
north of Stonehaven to a point north-east of Blair Atholl, a distance
of about 100 miles. This belt passes in a somewhat curving line
from the eastern coast to the head of Glen Isla, where it sweeps
round in a north-easterly direction almost to Ballater; thence it
turns westward, and crosses the Dee somewhere between Balmoral
and braemar. From the latter point it coincides roughly with
the Dee Valley as far as the Geldie Burn, after which it follows,
approximately, the belt of faulting in the Tilt Valley to within
3 miles of Blair Atholl. West of the Geldie, this area of decreasing
metamorphism corresponds approximately with the belt along which
the Moine Gneisses disappear; but east of the Geldie the two are
less intimately connected. When this belt of decreasing metamor-
phism attains its full development, we pass from the ‘sillimanite '-
aureole’ to that characterized by the presence of kyanite and

* See ‘On an Intrusion of Muscovite-Biotite Gneiss in the S.E. Highlands
of Scotland ’ Quart. Journ. Geol. Soe. vol. xlix (1893) p. 332.

416 MR. G. BARROW ON THE MOINE GNEISSES _ [ Nov. 1904,

staurolite; but on either side of the belt the metamorphism remains
singularly constant over very large areas.

In the Tilt Valley, as the gneisses are followed, they lose rapidly
their crystalline character. But, in addition to this, they also thin
away and change in composition, passing into a thin group of
equally parallel-banded rocks, known locally as ‘ the Honestones.’

To establish clearly and fully these changes in the aspect of the
Moine Gneisses, it was necessary to find a more or less continuous
section that should at once show both the decreasing crystallization
and the decreasing thickness. Such a section has been found in the
Tilt Valley, in the neighbourhood of Gilbert’s Bridge, where the river,
instead of continuing its usual rather straight course, makes a big
bend toward the north-west. Now the arch of this bend is at one.
side of the belt of decreasing metamorphism and thickness, while
the two ends are at the other; and it is by means of this section
that the whole explanation was ultimately arrived at.

(6) The Section at Gilbert’s Bridge.
(Map, Pl. XXXIIT & fig. 9, p. 444.)

Standing on Gilbert’s Bridge, and looking up the Tilt, we see
a typical section of the parallel-banded gneissose flagstones or
Moine Gneisses, striking up-stream, and having an even dip to the
south-east, at about 30°. Below the Bridge the same rocks are seen
for a tew yards, but farther down only small patches of gneiss are
exposed, as the rest of the section is composed of numerous infolds
of other beds. An examination of the river-channel shows that
these rocks are intensely folded, one of them, consisting of limestone,
being repeated no less than eight times in a distance of 150 yards.
This bed may be either in contact with the Moine Gneiss (here, at
times, highly quartzose) or separated by one or all of three beds or
bands. Of these, the most striking is a curious ‘pink rock,’ of
which the dominant constituent is obviously felspar. Another is a
dark and often tough schist, which varies somewhat in aspect ;
while the third is a little sill of hornblende-schist, which, by folding
on itself, may attain a thickness of more than 6 feet, but is some-
times not seen owing to a slight change of horizon, one of its
characteristic features. This little sill is of considerable importance,
as fixing, approximately, the horizon with which we are dealing.

The ‘ Pink Felspathic Rock,’ or rather material (for it is found in
the other sedimentary rocks) consists mainly of microcline. Where
purest, it forms a separate band, which, a little below Gilbert’s
Bridge, attains a thickness of 6 feet, owing, partly, to repetition by
folding. Some way below the Bridge it occurs as lenticles in the
quartzose rock. It is evenly disseminated through part of the
limestone in one place, while at another it forms a segregated patch,
which has so completely recrystallized as to simulate a pegmatite,
a mode of occurrence that has been noted over a wide area. A
specimen from the thicker band (10,534) is composed of abundant
microcline, quartz, decomposed felspar, and a considerable quantity
of green and brown mica, with a parallel arrangement. In some

Vol. 6o. | OF THE EAST-CENTRAL HIGHLANDS. 417

portions of this band microcline is even more abundant, the
principal accompaniments being green mica and granular sphene.

The Dark Schist occurs as discontinuous patches that lie next the
Limestone, and between it and the ‘ Pink Felspathic’ material, when
both are present. These dark patches have proved of exceptional
importance, and will be discussed later on.

The Limestone varies greatly in composition. As a rule, however,
it contains some snow-white, coarsely-crystalline calcite, and this
may be present in separate thin bands or mixed with other
minerals. In no case does this rock possess the grey coloration of
the typical Blair-Atholl Limestone and the Loch-T'ay Limestone.
One of the thicker exposures (10,526) contains abundant epidote
and microcline, the latter mineral identical with that of the Pink
Felspathie Rock, and a small quantity of either optically -anomaleus
garnet or idocrase. In one place the calcareous material is obviously
mixed with a pink felspar, forming a coarsely-mottled pink-and-
ereen rock. The green mineral is malacolite, and = pink the
typical microcline.

At the junction of the tough Dark Schist with the base of the
limestone occurs a finely-banded rock. The paler bands are com-
posed of abundant epidote and zoisite, with a smaller quantity of
hornblende and calcite. The darker films were more aluminous
originally, and are now composed of plagioclase and quartz,
associated with chlorite and biotite. There are small spots in this
part of the rock, dusted over with minute biotite-flecks, exactly as
in a typical hornfels.

It is thus apparent that the Limestone has not always the same
rock at its margin, and does not always rest upon the Moine Gneiss;
and there is clear evidence of a slight local erosion, or a small
hiatus in the succession.

Aiter a thorough investigation of the section below the Bridge,
the section above it may be examined. The rather massive and
highly-crystalline Moine Gneisses occupy the bed of the stream,’
but the Limestone lies in the bank above, and its base is ex-
posed in places, while at the mouth of the little burn at the northern
end of Dalginross Wood, both the felspathic rock and the
Limestone are seen. At the base of the latter is a finely-banded,
markedly-fissile rock. This fissility is due to the perfect parallelism
of a large number of pale-brown micas, associated with a small
quantity of actinolite. The rock is structurally a fine quartz-
felspar-biotite-granulite, with a considerable amount of
microcline, and a little carbonate and granular sphene (10,528). It
is of considerable importance, as suggesting a passage to the
felspathic material, and recalling the rock at Dalnacardoch and
the Gaick Burn.

A few yards farther up the main stream the Pink Rock is seen
again in contact with the Moine Gneisses, and continues in this

' See fig. 2, p. 404. For the photographs, from which this figure and
figs. 3 & 5 are reproduced, I am greatly indebted to Mr. Lunn, of the Geological

Survey.

418 MR. G. BARROW ON THE MOINE GNEISSES ___{ Nov. 1904,

position for some distance. Immediately below the big bend at
Auchgoul it changes suddenly in composition, in a manner that
seems to exclude the probability of an igneous origin.

The big bend just mentioned is cut in Drift, but at its northern
end, the Limestone, repeated several times by folding, is seen either
close to or touching the Moine Gneiss. One outcrop of limestone is
so much purer, and more like the normal: Blair-Atholl Limestone,
that it seems at first difficult to believe that we are still dealing
with the same bed.

Opposite the mouth of Glen Mhaire the river once more flows
along the strike of the rocks, and the Moine Gneisses are now seen
to be rather more quartzose and more finely-banded. In the bank
close to and above the river are several infolds of the Limestone,
associated in one case again with the Pink Felspathic Rock. A few
patches of tough Dark Schist, almost a Moine Gneiss at times
(10,548), intervene between the Limestone and thé Gneisses. In the
next long bend, immediately above Glen Mhaire, the river flows
exclusively over the Gneisses, which now le to the north-west of
the last outcrop of the Limestone. Beyond this bend, to the north-
west, the Moine Gneisses stretch for many miles in an unbroken
sheet.

A peculiar interest attaches to this section, for the curve of the
bend penetrates more deeply than usual into the belt of increasing
metamorphism ; and, comparing the rocks at the centre with those
at the two ends, the contrast, both in crystallization and thickness
of the bands, is well-marked. Moreover, if the steep bank at the
south-eastern extremity of this bend be ascended for a short
distance, the decrease in crystallization and the thickness of the
bands are still better seen. A similar change may also be noted in
the small quarry close to the roadside, just at the commencement
of the next bend.

A Jittle faither on, in the river-bank, the Limestone is clearly seen,
lying in an eroded hollow in the now-attenuated representative
ot the Moine Gneisses ; while apparently above the Limestone is
the Dark &chist, but in reality this is a deception, the meaning of
which is explained on p. 431. Still farther up the Tilt, the slow
decrease in the crystallization of the gueisses may be noted, as fold
alter fold of the Limestone is crossed. Accompanying this change is
an alteration of the material of which the gneisses were originally
composed. It is obviously becoming more of the nature of a
sandy mud.

We now reach the famous section of the Glen-Tilt Marble-Quarry,
known to geolegists since the days of Hutton, Playfair, McCulloch,
and Murchison, who noted its 1esemblance to certain limestones and
their associated rocks in the North-Western Highlands. Here the
Limestone is folded again and again on itself,so as to form a rather
thick mass; neat to it comes the little sill of hornblende-schist,

2 See Quart. Journ. Geol. Soc. vol. xvii (1861) p. 228, second footnote.

he

Vol. 60.] OF THE EAST-CENTRAL HIGHLANDS. 419

seen at Gilbert’s Bridge, and many other parts of the section already
traversed. This, in turn, is succeeded by the Parallel-Banded
material (10,556), now obviously an even-banded alternation of fine
sandy and muddy sediment. This rock can be at once identified ;
it is a phase of the Honestones, a well-known member of the
Highland Succession. ‘The Limestone itself is of special interest, not
only for its beauty, for which it was once so famous, but also froma
peculiarity in its composition. It contains a considerable amount
of serpentinized forsterite along certain bands. The rock was cut
parallel to these bands, so that, when set up, it gives the deceptive
appearance of a thick mass of serpentine. A little farther up the
river, the thinness of the parallel-banded Honestones allows the
white margin of the Quartzite to come into view, and the two are
seen folded together again and again, almost to the end of the sharp
bend, where the extraordinarily-straight and deep portion of Glen
Tilt commences. Jn this part of the section it will be noted that
the Honestones vary somewhat in composition, being slightly more
siliceous at one point than at another. They vary also in thickness,
and in one place either thin out entirely or become a mere film, so
that the margin of the Limestone is almost, if not quite, in contact
with the Quartzite. Just before reaching the sharp bend already
mentioned, we suddenly come upon a good-sized exposure of the
typical bluish-grey Blair-Atholl Limestone, and it seems at first
incredible that this can be the same limestone as the one so often
referred to: but in the course of some recent traverses it was
clearly proved that they are really one and the same. A little
farther up the stream the Limestone is succeeded by the Dark Schist,
rich in kyanite, that is so abundant in portions of the Braemar
area, and all trace of the Moine Gneisses close to the Limestone has
now disappeared.

This long section thus clearly shows that the parallel-banded
Moine Gneisses, as they cross the belt of decreasing crystallization,
not only become less crystalline, but that they gradually change in
composition, passing into the ‘ Honestones, which were originally
a finer and more muddy type of sediment, slowly thinning away as
they do so. Where present in mass, the original thickness is so
enormously increased by folding that only one side (that next the
Limestone), whether top or base, can be seen. When, however,
they have become very thin, the other side also is visible, and the
rock that lies next this is the fine white margin of the Quartzite. It
is thus clear that the Moine Gneisses lie between this Limestone and
the Quartzite, and that they may be regarded as the flaggy margin
of the latter. Sections have been made to illustrate the pro-
gressive change in the nature of the original material of the Moine
Gneisses. The first (10,555) was taken from the small quarry close
to the road, above the junction of Glen Mhaire with the Tilt. It
is a fine-grained banded rock, built up of alternate layers of
quartzose and grey granulitic gneiss, or perhaps schist, for the
decreasing crystallization to the south-east already begins to be noted
here. The structure of the part of the rock that has been cut is

420 MR. G. BARROW ON THE MOINE GNEISSES __ [ Nov. 1904,

essentially that of a very fine or less crystalline Moine Gneiss,
but there is little microcline present, and the biotite is reddish-
brown. Another specimen of the more muddy, but still parallel-
banded material, was taken from the Tilt close to Marble Lodge
(10,556). This is grey throughout, but the darker bands were
clearly finer mud originaliy. ‘These are rich in red biotite and
white mica associated with plagioclase, in exactly the same way as
in parts of the Dark Schist to be described later. The hghter bands
are composed of quartz and decomposed plagioclase, with a little
microcline, and possibly some orthoclase. A little biotite, chlorite,
and white mica are also present. This rock thus forms a link
between the more quartzose, banded material and the curious
felspathic and micaceous rock, containing much dark dust, which is
so typical of the Black Schist near the Little Limestone.

Returning to the little stream, above Gilbert’s Bridge, at the
northern end of Dalginross Wood, and examining its bed, we find
the change in the nature of the parallel-banded rocks taking place
far more rapidly, for we now cross this zone at right angles, instead
of diagonally.

The section below Gilbert’s Bridge shows phenomena essentially
similar to those already recorded. It is, however, far more difficult
of access, and the absence of bends, and the fact that the river runs
more nearly along the course of the strike, make the progressive
change less clear. There are, nevertheless, a few points of special
interest. The band nearest the limestone in the Moine Gneisses
is often a pure white quartzite, which can be distinguished from
the white margin of the Main Quartzite only by the fact that it
does not weather rusty-brown. As before, small patches of Dark
Schist occur occasionally between the Limestone and the Gneiss, and
one of these, 250 yards below the bridge, contains a considerable
quantity of kyanite.

At the sharp bend of the Tilt in Crombie Wood (see map,
Pl. XX XIII) there is an especially-fine exposure of the Pink Rock,
partly in thin pure bands, partly commingled with other material.
A little south of Crombie Burn, on the west side of the Tilt, is a
small scar, composed of very finely-banded and much less crystalline
material, showing that a change takes place below Gilbert's Bridge
similar to that already described above it. The stages of the change
are not, however, so well seen, and the decrease in crystallization is
not so rapid.

(c) The Banvie- Burn Section.

A section somewhat similar to that of Gilbert’s Bridge occurs in
Banvie Burn, at the Whim Plantation, to the north-north-west of
Blair Castle. At the western edge of the wood, close to the burn,
the typical Moine Gneisses are exposed in a quarry (already referred
to, p. 409), and, descending the stream from this point, we cross the
usual parallel-banded rocks, locally more siliceous, until we reach

Vol. 60. | OF THE EAS?-CENTRAL HIGHLANDS, 421

the first outcrop of the Limestone. Between this point and the next
bridge, a distance of 250 yards, the Limestone is repeated no less
than seven times by folding. As before, no two of these outcrops
are exactly alike; but in this case the apparent suddenness of the
change is considerably increased, owing to the fact that we now
cross the folds at right angles. Certain materials, such as pale
hornblende, calcite, granular sphene, etc., are rarely wanting ;
microcline may be either abundant or absent. The second out-
crop, above the lower bridge, is mainly composed of very pale-green
hornblende, while that next the small mass of hornblende-schist
contains idocrase, garnet, and pyroxene. Below the hornblende-
schist the limestone is coarsely mottled green-and-white, the green
patches consisting of radial bundles of pale hornblende. The western-
most outcrop is a nearly-white and rather siliceous limestone,
identical with that seen in several places below Gilbert's Bridge,
and in many other localities ; while that part of the Moine Gneiss
which is next the Limestone is also highly quartzose.

Again, as in the Gilbert’s-Bridge section, small patches of Dark
Schist, varying both in thickness and composition, occur locally
between the Limestone and the Moine Gneiss. The ‘ Pink Rock’ is
also present in one place, commencing as a thin infold at either end
of the small mass of hornblende-schist, and thickening towards the
centre of the outcrop. Here it seems to merge insensibly into the
top of the Moine Gneiss, which just appears, in the bed of the
river (19,521).

(d) The Hiatus in the Succession.

The rocks associated together in the sections hitherto described
are as follows :—

1. The Limestone.

2. The Dark Schist (in lenticles).

3. The Pink Felspathic Rock.

4. The Moine Gneisses; elsewhere the Honestones.

). The Epidiorite-sill, not always at the same horizon.

6. The white edge of the Quartzite, succeeded by the main bed.

It has already been noted that the Limestone may be in contact
with any of the first five bands, and in one place it almost touches
the last, if it does not quite doso. There must consequently
be a small hiatus or line of erosion at the base of the Limestone.
But, in addition to the bands enumerated above, there are others
present in certain parts of the Aberdeenshire area, and apparently
absent here. It is consequently advisable now to fix exactly the
order of succession of the rocks, to ascertain the extent of the
hiatus, and see how far it throws any doubt on the fact that we
are dealing in the main with a regular succession. As the full
sequence is exposed in the area south of Braemar, which lies in the
belt of ground under investigation, this succession in the Braemar
area may now be conveniently described.

Q.J.G.S. No. 240. 26

Fig. 4. (See note on p. 423.)

GEOLOGICAL MAP
OF
GLEN :
=Invere
Arms

SCALE
1% inches =1 mile.+
= ———— yy >

ates ae
sve aer,
/ \. we r As
Pe BRC a
7OETS N\A “ant

DE Ge

z
su

ee

Zy
im
;

LK

G00 00d «A
ZPXSSAGY,
aetna arias

whiggin

eg

EXPLANATION Little Limestone ---
———————— Dark Schist

Alluyivm Main Limestone and-=————4
Quartzite-= == === ee Cale -Flintas --~---- pt
Folded Passage -Rocks Granite and
& edge of Quartzite Quartz-Porphyry ---
Vassage-Rocks with In- ; Epidiorite and
folds of Dark Schist &e._ Hornblende-Schist..-

Vol. 60.| MOINE GNBISSES OF THE BAST-CENTRAL HIGHLANDS. 423

(e) The Succession in the Braemar Area.

The Sequence.—One of the most striking features of the
scenery of the EKast-Central Highlands is the great chain of quartzite-
mountains that stretches from Beinn y Ghlo, near Blair Atholl, to
Mor Shron, close to Braemar. Parallel to this are minor chains,
composed of the same material. While the quartzite is intensely
hard, and resists denudation, the rocks associated with it, and
in particular a bed of limestone, are much softer, and yield readily
to erosion. ‘These beds, in consequence, have weathered away to a
great depth, and hence much of the district is characterized by an
alternation of high ridges and deep valleys; the trend of which is
determined by the strike of the outcrops of the Quartzite. It is
with the composition and order of succession of the rocks forming
this special type of scenery that we have now to deal. The locality
selected for the purpose lies 2 miles south of Braemar; but other
parts of the district will be referred to, for the purpose of aiding the
investigation.

The succession in this group of rocks, in this area, whether
ascending or descending, is as follows :—

1. The Central-Higbland Quartzite.

2. The Parallel-Banded Series; Honestones, ete. (passing into Moine
Gneisses).

3. The Little Limestone.

4, The Dark or Leaden Schist.

5. The Main Limestone.

6. The altered, parallel-banded Calcareous Shales (Calc-Flintas).

1. The Central-Highland Quartzite.—The Quartzite was
originally a bed of sandstone, more felspathic in some parts than
others, that has been intensely folded on itself, so as to build up
enormous masses of highly-quartzose rock. It is conveniently
called a ‘ quartzite, because, however much recrystallized, it almost
always retains the angular weathering of an ordinary quartzite.
Often there is no sign of the mechanical deformation usually met
with in the other members of the series ; and it is clear that it was
altered to a quartzite, not only before the crystallization of the
Highland rocks took place, but prior to their crushing. Over almost

Note on the Map, fig. 4, p.422.—In this map the sequence is built up. Here,
again, the stream and scar-sections are mostly clear, but the flatter ground is
greatly obscured by thin peat and Drift; owing to the intense folding, there is
often no sharp junction between the different rock-groups. Starting from the
margin of the Quartzite, we sometimes see, first the edge of the Quartzite
repeatedly folded with the Passage-Beds, then the Passage-Beds folded with the
Little Limestone and Dark Schist, and, finally, the Dark Schist only. There
is, however, in many cases, a fairly-sharp junction with the Quartzite. The
line separating the Passage-rocks from the Dark Schist often implies simply
that one rock is the dominant component on one side of the boundary, the
other rock on the other. The outcrop of the Little Limestone is so narrow as
to be often untraceable. The quartz-porphyry outcrop, shown west and north-
west of Newbiggin, also extends to the east of the burn, immediately north of
the Main Limestone.

262

424 MR. G. BARROW ON THE MOINE GNEISSES __ [{ Nov. 1904,

the entire area, the Quartzite varies little in appearance and com-
position, and can be divided up into three parts, as follows :—

(a) The fine white edge of the Quartzite, characterized by its
whiteness and its generally-fine grain, and usually containing but
little felspar. ‘There is often present, however, a considerable
amount of unevenly-distributed pyrites, which, on decomposition,
imparts a rusty-brown aspect to this portion of the rock, and this
rusty aspect is even more characteristic than the unaltered white
colour. It cannot be too clearly understood that this is the only
margin of the Quartzite ever met with in the whole of the area under
discussion ; the reverse side, whether the top or the base, is never
seen.

(6) The Quartzite, with dark lines of heavy minerals.—This part
contains a little more felspar than the last, although still practically
white. ‘The fine dark lines in which the heavy minerals occur
ndicate the bedding; at times they show that the rock was
originally false-bedded.

(c) The porous Quartzite—This portion of the rock, which
commences some 6 or 8 feet from the outer margin, must have been
coarser originally, and contains more felspar; at times it is
markedly felspathic. Owing to the indestructible nature of the
quartz, the felspar in an exposed face weathers out completely,
leaving a number of small holes in a homogeneous mass of quartz,
and imparting to this weathered face its typical porous aspect.

The white edge of the Quartzite can be recognized in almost
every clear section, south of Braemar, where the junction with the
other members of the series is exposed. In what may be con-
veniently termed the type-locality, it occurs close to the roadside
north of Coldrach. ‘The other parts of the bed may be seen
by ascending almost any of the quartzite-mountains in the neigh-
bourhood.

2. The Parallel-Banded Series.—Immediately next the
white edge of the Quartzite is a rock composed of a few thin,
yellowish, quartzose bands, separated by pale, cross-cleaved,
micaceous films: obviously a passage-rock. This is succeeded by
greyer material, still in alternating layers of more siliceous’ and
more micaceous composition, the latter again often cross-cleaved.
In addition, the face of the micaceous bands is often covered with
small spots or projections, proved in many cases to be minute
garnets. As we recede from the main Quartzite, the micaceous
material darkens in colour, and becomes more like the Dark Schist
above; moreover, it exceeds the grey siliceous material in amount.

The section here seen differs trom the typical Honestones in
the greater proportion of shaly material between the more
siliceous bands in the original rock. Moreover, this softer material
contains much of the dark dust and clastic chlorite characteristic of
the horizon next above. The parallel-banded or passage-rocks are
seen in part near Coldrach, and in the low ground between Glen

* See Pl. XXXVI, fig. 2 (No. 136).

Vol. 60. | OF THE EAST-CENTRAL HIGHLANDS. 425

Clunie and Glen Callater, continuing a short distance up the latter.
Two other exposures occur in the neighbourhood : one in the nose
and crest of the hill overlooking the junction of the two streams ;
the other along the crest of the southern face of the corrie behind
Coldrach. It is easily seen that these passage-rocks, before they
were folded, could not have been more than a few feet thick.

3. The Little Limestone.—The typical form of the Little
Limestone, as seen in Glen Callater and Glen Clunie, is a remarkable
rock, the origin of which becomes clear only after the bed next to it
has been examined. ‘The latter shows conclusively that the Little
Limestone was originally an admixture of calcite, very finely-divided
clastic chlorite, and marcasite, with possibly a small portion of car-
bonaceous material. When raised toa high temperature, an unusual
combination of elements took place, resulting in the production of a
glass-white hornblende (tremolite), in which hme and magnesia are
mixed in equal parts, the iron-ore being rejected. The latter being
dusted through the rock, which is essentially of massive habit,
imparts to it an almost black colour, although the dominant
constituent is glass-white. Occasionally yellowish films, mainly
composed of epidote and zoisite, occur in it. In some cases there
was slightly more lime than was necessary for the formation of the
tremolite, and this is now scattered through the rock in small
grains of crystallized calcite. The rock often bears a close resem-
blance to an epidiorite, and has to be carefully examined in order to
place its identity beyond dispute. So long as the Dark Schist, to be
described next, is of constant composition, the Little Limestone
retains this aspect, and has been recognized as far away as the
neighbourhood of Ben Vrackie, near Pitlochry; but, if the Dark
Schist changes in composition, the Little Limestone changes too.
The rock is met with in Glen Callater at the first small rapid above
the bridge, though another and more interesting outcrop occurs at
the sharp bend farther up, a little beyond the quarry, in the flagg
hornfels. The total number of outcrops in this neighbourhood is
almost incredible, and shows conclusively the intense and com-
plicated folding of the rocks.

4. The Dark Schist, with the ‘twinned-chlorite-rock’
and the ‘felspar-rock.—In a type-area, such as that south
of Auchallater, where the Dark Schist attains its full development,
it is characterized by the presence of an excessive amount of mag-
nesian silicates, due to the existence in the original rock of an
extraordinary quantity of finely-divided clastic chlorite. This
material attained its maximum in the film of rock next the
Little Limestone (the Twin-Chlorite Rock), and this is now seen in
the form of abundant twinned crystals of chlorite. From this zone
upwards, the clastic chloritic material steadily diminishes, on the
whole, attaining its minimum close to the Main Limestone,
where the most characteristic aluminous silicate is kyanite, or
more rarely audalnsite. containining no magnesia, As we descend,

426 MR. G., BARROW ON THE MOINE GNEISSES i Nov. 1904,

staurolite appears, and twin-chlorite and other magnesian silicates
steadily increase in amount. Where the metamorphism is more
intense, the same phenomenon is shown by the greater abundance
of cordierite in the lower part of this bed, while andalusite is more
abundant in the upper.

Another characteristic of the zone a little above the Twin-
Chlorite Rock, is the presence in large quantity of a felspar proved by
Dr. Teall to be of the oligoclase-andesine group, containing curving
lines of dark dust (the ‘Felspar-Rock’). It occurs, to a small extent,
through most of the bed, but appears to be abundant only towards
the lower part. Its distribution seems to be the same as that of
the tremolite-rock ; the two, so to speak, go together, and have been
recognized as far away as the neighbourhood of Druid Farm,
north-west of Ben Vrackie (10,777). The dark dust that occurs in
this felspar is met with throughout the whole of the Dark Schist in
the Braemar area, but as a rule is most abundant about the T'win-
Chlorite Rock. Here, a small portion of it is undoubtedly graphite,
though, in most cases, very little of this material is of that nature.
The dark dust seen under the microscope is often in part leucoxene,
but by far the greater portion of it is iron-ore; its real origin was
suggested by Mr. A. Dick’s examination into the cause of the blue
colour of unweathered London Clay. ‘This proved to be the pre-
sence of a large number of minute spheroids of marcasite, and there
can be little doubt that the dark dust of these rocks had a similar
origin. ‘The iron-ore in these rocks is slightly magnetic, and, if
a specimen be ground to very fine powder, the greater part of the
rock can be picked up with a magnet, owing to the even dissemination
of the iron-ore throughout it.

5. The Main Limestone.—the typical Main, or Blair-Atholl
Limestone, is well seen at the southern end of the corrie opposite
Newbiggin in Glen Clunie, where it possesses the characteristic pale
bluish-grey colour and crystalline aspect. The Clunie area shows
well the tendency of the rock to become more impure as it approaches
the belt along which the Moine Gneisses set in; or where there
is a hiatus in the succession, and parts of the beds are missing,
As a rule, however, only the basal portion is markedly impure,
and as (in many cases) it is this part repeated by folding that is
really seen, it gives the erroneous impression that the whole bed is
impure.

6. The Calc-Flintas, or Parallel-Banded Calcareous
Shales.—This bed consists of thin lamine alternately richer and
poorer in lime. ‘The peculiarity from which it takes its name, is
its more or less persistent flinty aspect, due to the presence of a
variable number of bands composed of quartz, biotite, calcite,
pyrites, and leucoxene. These originally contained much quartz
and clastic chlorite in a fine state of subdivision, which, when
heated, form a kind of hornfels at a specially-low temperature
and this hornfels is so intensely hard, that it resisted shearing

Vol. 60. ] OF THE EAST-CENTRAL HIGHLANDS. 4

movements anterior to the main crystallization of the Highland rocks.’
Associated with the flinty bands are much paler, almost white,
layers. The dominant constituents of these are white pyroxene and
calcite. Other pale bands rich in epidote occur. All these phases
may be found in the Cale-Flintas associated with the Main Lime-
stone at the corrie opposite Newbiggin. They also show another
feature of the rock: here and there special bands occur, differing in
type from the normal. At this locality, g few bands have an almost
micaceous aspect, owing to the presence of a great number of small
parallel crystals, determined by Dr. Flett to be pale hornblende.
he proportion of the more flinty material is small here, but the
parallel banding is well shown. A very small infold of the pyroxene-
bands is associated with the limestone in the bed of the Clunie at the
southern end of Auchyndrine (Braemar).

(f) Further Evidence of the Succession.

It has already been shown that the Quartzite is succeeded by the
Parallel-Banded Rocks; the best locality for ascertaining the nature
and succession of the zones above the latter occurs in Glen Callater,
at the bend of the stream above the quarry in the flaggy hornfels,
above the bridge at Auchallater. At this bend, when the water is
low, we see first the Little Limestone (tremolite-rock, S091); next
this comes the ‘l’'win-Chlorite Rock (8092) of a characteristic
dead-black, due to the presence of graphite ; while next this again
come the various portions of the Felspar-Rock (8094, etc.), often
known as the Felspar-Hornfels” of Glen Callater. At the southern
edge of the quarry (see map, fig. 4, p. 422), in the daggy horntels,
we see again the Felspar-Rock, with its glistening crystals of felspar
rendered dark by the presence of the dark dust, which serves to fix
the horizon of the recks within the quarry. These are characterized
by a flagey habit, the splitting-faces being coated with bronzy mica
and, at times, with small spots. The different bands vary in colour
and compactness. ‘The darkest have a somewhat flinty cross-fracture,
and contain a great quantity of fresh andalusite showing the typical
pink pleochroism. Except on the splitting-face the amount of biotite
present is small, but there is a considerable quantity of shimmer-
aggregate material replacing some alumina-silicate. Quartz is sub-
ordinate in amount, and a small quantity of felspar is present. The
typical dark dust is abundant, and the structure of the rock is
essentially that of a hornfels. A band, in which the flinty cross-

* The hornfels-like aspect of this rock, traceable over half the breadth of
Scotland, is due to the fact that, after induration, it usually escaped crushing
owing to the plasticity of limestone at a high temperature (as proved by the
experiments of Prof. Adams & Dr. Nicolson). ‘The limestone next the flintas gave
way readily and relieved the latter from the crushing stresses. Many other
rocks must have been similarly indurated, but possessing no such yielding
margin they have been since crushed.

> See SIV, p. 442, at the end of which the bearing of this rock on the absence
of metamorphism due to the neighbouring mass of granite is discussed.

428 MR. G. BARROW ON THE MOINE GNEISSES ___[{ Nov. 1904,

fracture is not so marked, contains less andalusite but far more
shimmer-aggregate material. The most micaceous part of the rock,
with numerous spots on the splitting surface, shows marked parallel
structure under the microscope, and is composed of abundant pale
biotite associated with quartz, a little felspar, and some andalusite.
The elongated micas sweep round small patches in which no parallel
structure is seen, and these are probably eyes of material that have
been indurated anterior go the main crystallization of the mass,
and have thus escaped crushing.

Now, the rock so rich in andalusite is seen again close to the Main
Limestone, both at the head of the corrie about a mile to the north-
north-east of Auchallater, and 2 miles to the south-south-west, in
the corrie opposite Newbiggin. It is thus clear that there is not
much more rock present in the whole of the Black Schist than the
few bands above described, and it cannot have been much more
than 15 feet thick originally. This will be understood by following
up Glen-Cailater Burn as far as the ford; there, except the
granite, nothing is seen but the Felspar-Rock and the closely-
adjacent material, repeated incessantly by folding. A difficulty
arises from the different phases of metamorphism ; for, when the
material was considerably heated anterior to the main meta-
morphism and indurated so as to escape subsequent crushing, it is
found, in this area, finally to crystallize as an andalusite-hornfels; but
generally, if much crushed, it finally assumes the form of a kyanite-
schist. In both cases, it will be noted that it is a non-magnesian
silicate that is so abundantly developed in the highest band. In
some cases, the andalusite appears as a number of minute laths that
in their mode of occurrence simulate kyanite, and in other localities
are replaced by kyanite. This gradual diminution in the amount of
clastic chlorite present in the original shales has been noted over a
wide area, and suggests continuous deposition or an unbroken
sequence from the Little Limestone to the rock rich in kyanite or
andalusite next the Main Limestone.

For the purpose of building up the sequence the most valuable
evidence, however, 1s obtained from the association of the Main
Limestone with the Calc-Flintas, or altered, parallel-banded, calcareous
shales. The accumulated experience of years of detailed mapping
makes it certain that in these two rocks we have a record of con-
tinuous deposition, or a portion of an original and unbroken sequence :
no other bed in the series can intervene between them, and in any
account of the succession they must always be taken together.
Again, experience has shown that, with very rare exceptions, the
calcareous shales always overlie or succeed the main bed of Lime-
stone. Now these Calc-Flintas occur in most of the broader valleys
over a very large area, especially where the beds between the
Quartzite and the Main Limestone are wholly missing. It must be
remembered that in the former case it is not merely the original
thickness of the beds that is missing, but the great mass of rock
built up by their intense folding; a large gap is consequently left

Vol. 60. ] OF THE EAST-CENTRAL HIGHLANDS. 42%)

to be filled up by the folded higher beds. This happens along
almost the whole length of the south-eastern side of the Ben-y-Glioe
Mountains, which rise from comparatively low ground to a height
of more than 3600 feet above sea-level. The gap to be filled up is
exceptionally large, and in consequence the largest known outcrop
of the Cale- Flintas occurs here, and we see in addition a small
number of thin infolds of the altered dark shale originally above the
Calc-Flintas. But over the whole of the rest of the country, the
rock on the reverse side of the flintas to the Main Limestone is
never seen; and the flintas must in all other cases be either the
highest or lowest rocks in this part of the South-Eastern Highlands,
and the evidence is conclusive that they are the highest.

This view, that there is a descending succession from the Main
Limestone to the Quartzite, is greatly strengthened by the frequency
with which a hiatus occurs at the margin of the Main Limestone, a
good example of which is shown on the map (fig. 4, p. 422) in the
corrie opposite Newbiggin. Sometimes the whole of the Dark Schist
and the Little Limestone are missing, sometimes portions only; but
as the investigation proceeds, it will be seen that the line of erosion
at the base of the Main Limestone is not by itself sufficient to
explain all the phenomena met with.

(g) Meaning of the Patches of Dark Schist and Proof that
the Sequence is incomplete in the Glen-Tilt Area.

The meaning of the patches of Dark Schist in the Gilbert’s-
Bridge and Banvie-Buarn sections can now be investigated.’ Below
Gilbert’s Bridge, close to Crombie Burn, one of these patches inter-
vening between the limestone and the Moine Gneiss is a kyanite-
garnet-stauroiite-schist, obviously well above the bottom of the
dark shale, but almost certainly a little below the top. There are
several other smal] patches below Gilbert’s Bridge, and these appear
to be approximately at the same horizon. Nearer Gilbert's Bridge
a film of tough schist occurs between the Limestone and the Pink
Felspathic Rock. This (10,549) is a highly-micaceous rock, built
up of alternating films of quartzose and micaceous material ; the
latter consist largely of white mica and chlorite, often env eloping
large cracked and decomposed garnets. Jron-ore is abundant, both
in good-sized grains and as fing dust, and it is often embedded ina
clear, almost glassy material, which is known to be plagioclase
although it here shows no striation. There can be little doubt
that this is a siliceous modification of the Felspar-Rock, and it
illustrates a difficulty that oceurs repeatedly. As the area is
approached where the more sandy material, now forming the Moine
Gneisses, was deposited, the Dark Schist tends to become slightly
more siliceous, and differs slightly in appearance from the rocks of
the type-area. If the siliceous material increases beyond a certain
point, the zone can, of course, be no longer identified. So far as is

‘ See Map, Pl. XXXIII.

(OGRA Oe WF ‘Tu ay) U0 x* YSLAIISD UD hig payowrp St gods au, ) ‘ab poy a1qQ40
mojag ‘BUT, Wayg § awopsoumryT winyy ay? fo asng ay} ay sassiauyy auropy aux wi Uorso.? fo DWT —"G “SLT

Vol. 60. | MOINE GNEISSES OF THE EAST-CENTRAL HIGHLANDS. 431

known at present, this increase is more marked in the lower part of
the Schist than in the upper.

Of all these patches of Dark Schist, the most interesting is that
which lies apparently on the top of the Limestone in the river-
bank at the first bend below Marble Lodge. (See fig. 5, p. 430.)
Here the Limestone is shown resting in an eroded hollow of the
attenuated Parallel-Banded Rocks into which the Moine Gneisses
have slowly passed, while lying apparently above the Limestone
is the patch of Dark Schist now mentioned. It is a dark, somewhat
massive rock, evidently rich in biotite, but containing a number
of very minute lenticular films of quartz, suggesting that, as
we approach an area of more sandy deposition, the Dark Schist

Fig. 6.—Diagraim showing the Dark Schist and Parallel-Banded
Rocks apparently on opposite sides of the Limestone, while in
reality they ave on the same side.

A B
Sante bh yw howe ke Ul el on Ltzzezestarse
“eon on uv ie) et aT

on ee ey at gO) a 0 gam Darl Schist

ee
—
———
SS
—

After folding, so that the point A lies directly
over the point B.

has become more quartzose (10,421). The rock contains much
granulitic quartz, which represents the minute lenticles referred to,
and a great quantity of more or less aggregated crystals of red
biotite ; the typical felspar with much dark dust, like the Glen-
Callater hornfels, is abundant, and there is one crystal of andalusite.
Itis clearly a slightly-siliceous phase of the upper part of the Felspar-
Rock. ‘The occurrence of the Felspar-Rock above a thin band of
Limestone, with the Parallel-Banded Rocks below it, seems, at first,
conclusive evidence that the limestone must be the Little Limestone.
In reality it is an ideal example of the kind of deception so often
produced by folding of a slightly-vague succession in the Central
Highlands. If we consider carefully the meaning of the sporadic
occurrence of lenticular patches of Dark Schist below Gilbert’s
Bridge, it becomes obvious that the folding may so involve one of

432 MR. G. BARROW ON THE MOINE GNEISSES [ Nov. 1904,

these patches, as to make it appear that it is on the opposite side of
the Limestone to the Parallel-Banded Rocks, while, in reality, it is
on the same side. ‘The foregoing diagram (fig. 6, p. 481) shows
clearly both the deceptive structure and its explanation.

Similar patches of dark schist occur in Glen Banvie, and of these
the most interesting lies next the small mass of hornblende-schist
100 yards above the lower bridge, in the Whim Plantation. It
consists of two parts: one very dark, with a dead-black film, and a
fine grey siliceous schist or granulite. Three microscope-slides were
made of the dark portion (10,551-10,553), and these show that part
of the rock contains much dark dust, rich red biotite, while epidote
and zoisite are abundant along certain lines in an adjacent portion.
Another is tougher and darker, intensely chloritic, containing
decomposed garnets and a little andalusite ; a third is composed of
felted white mica and pale chlorite. The dead-blackness of part
of this rock, along with the occurrence of epidote and zoisite along
certain lines, suggest that we may have here a representative,
though very thin, of the Little Limestone; for the Little Limestone
will be shown later to pass into an epidote-zoisite rock, containing
much dark dust, before its outcrop is finally lost. It is the only
known occurrence of this dead-black material within a short
distance of the actual Moine Gneisses. The rock next it is very
fine in grain, and composed of white and dark mica arranged
parallel in a fine granular matrix of quartz and felspar. It can
be very closely matched from the Honestones and, by its texture,
shows how rapidly the rocks become finer in grain as we cross the
belt of decreasing crystallization.

The examination of these patches of schist clearly shows that they
belong to different horizons; not only is there a hiatus at the base
of the Main Limestone, but there is also liable to be one at the top
of the Moine Gneisses, or the Parallel- Banded Rocks into which they
pass. It seems as though, in an area where the originally-coarser
material of the Moine Gneisses was deposited, the currents were
strong enough, either to prevent the deposition of the fine mud, or
to wash it away after it was deposited. Owing to the shifting
nature of the currents, patches of the fine mud were, however, left,
and these lie at different horizons. The finest material of all was
probably that which formed the Little Limestone and the Twin-
Chlorite Rock, and this is the portion of the sequence that is most
persistently missing. But, as already stated, the total thickness of
the Dark Schist was quite small, and the hiatus is of no great con-
sequence. In connection with it, however, we note a remarkable
fact: it is succeeded by a limestone, very impure and very variable
in composition. Now, at the top of the Upper Lias in East York-
shire a similar sifting-away of the fine mud took place, followed
by the deposition of a very impure and very variable limestone, now
altered to ironstone, the Dogger or base of the Lower Oolites.
Proceeding in one direction, the succession beneath this impure
limestone becomes complete at Blea Wyke, on the coast south of
Robin Hood’s Bay. Proceeding in the opposite directicn—inland—

Vol. 60. | OF THE EAST-CENTRAL HIGHLANDS. 433

the sifting-away occasionally takes a stronger form, and large holes
were dug in the soft dark mud, one of which occurs at Bilsdale
(nearly 100 feet deep), the other near Rosedale Abbey; in both
cases, the eroded hollow was filled up with impure limestone.

No further evidence, bearing on this investigation, is met with
till the northern end of the long straight portion of the Tilt Valley is
reached. Here, just above the junction with the An Lochan, a
section occurs closely resembling that at the sharp bend in the Tilt
at Crombie Wood, below Gilbert’s Bridge: the Pink Felspathic
material being again present. Ascending the river-bed from this
point, when the stream is low, the Honestones can be seen to pass
gradually into fine Moine Gneisses. This part of the river is some-
what obscured by numerous small protrusions from the Glen-Tuilt
complex ; but the passage can be well seen a little above Pool Tarf,
along the bed of the Tilt, and in the first small stream south
of the Tarf. Here, the passage of the Honestones into the Moine
Gneisses is practically unbroken. ‘This is due to the lucky accident
that only the less markedly-siliceous part of the Honestones is
present; a single infold of the more markedly-siliceous portion
would have broken the continuity of a gradual change.

On looking at the map, the reason why this gradual change can
be traced becomes at once obvious. As in the Gilbert’s-Bridge
section, the Tilt once more makes a Jarge bow. As before, one end
of the bow lies at one side of the belt of decreasing alteration, the
other almost at the opposite side; it does not quite do so, and this
is why, in addition, the small burn has to be ascended in order to
see the full change.

(h) The Falar Area.

Considerable light is thrown on the present investigation by the
clear, continuous sections in the deep gorges that characterize the
Falar portion of the Tilt drainage-area. The most convenient
starting-point lies at the junction of a little burn with Glen Mohr,
immediately north of Glen Bheag. In the lower part of the little
burn, the small sill of hornblende-schist and part of the Dark Schist
are exposed, repeated several times by folding. In the bed of the
main stream below, is an excellent section of the Honestones with
the Little Limestone next them, and beyond this a high bank
composed of the Dark Schist. The locality was often visited in
former years by farmers and shepherds, who came from considerable
distances to procure a certain portion of the parallel-banded material
to be used as honestones, and it is to this fact that the beds owe their
distinctive name. These Honestones are characterized by their even
colour-banding, and are composed of a number of alternating softer
and harder layers, most of which contain a considerable amount of
biotite, arranged parallel to the banding or bedding. The portion
of the rock nearest the Little Limestone is, on the whole, the
softest; and it at first contained most clastic chlorite. This often
occurred in little felted films, obviously identical originally with the

434 MR. G. BARROW ON THE MOJNE GNEISSHS [ Nov. 1904,

felted biotite-films in the Moine Gneisses, and along which the rock
readily splits. Close to the Quartzite, a few far more siliceous pink
and white bands occur, and in these muscovite is more abundant and
there is less biotite. The intermediate portion is a thinly-banded,
fine-grained, brpwn or grey rock, obviously containing a great deal
of fine brown mica. ‘This is the dominant constituent of the group,
and in a typical example (9797) the more siliceous bands are
composed of a singularly-even admixture of quartz-grains and
minute flakes of biotite, with, possibly, some water-clear felspar ;
the structure is essentially that of a fine biotite-granulite. The
more micaceous portion contains far less quartz or felspar, and is
largely composed of finely-felted brown mica, with which some larger
‘ erystals of muscovite are associated, set athwart the foliation as in
a spangled gneiss. These micaceous films are peculiarly interesting,
for they have been met with over a large area, among others, on
the north-west side of Ben Vuroch.'

The Little Limestone, though still containing the typical dark
dust, differs from the tremolite-rock in the fact that the bulk of the
hornblende is now actinolite. A still more important difference
occurs in the schist forming the steep bank above the stream. It
is lighter in colour thau the typical Dark Schist, and a series of
sections shows that it originally contained far less clastic chlorite
and fine dark dust; still, the maximum amount of chlorite occurs
in the portion of the bed next the Little Limestone (9794, 9792,
9795, 9790). It is thus seen that, although we have here the full
sequence of the beds about the Little Limestone, each band differs
slightly in composition from the type-rocks of the section about
Auchallater. It places the true position of the Honestones, however,
beyond dispute, and is especially important because it will be seen
immediately that this is, so to speak, the most siliceous phase in
which the Honestones are ever known to occur in this area accom-
panied by the full sequence. So soon as they become markedly more
siliceous, the Little Limestone and part of the Dark Schist appear to
be almost always missing in the area here described.

This fact can be seen at once by ascending Glen Mohr. A little
above the junction with Glen Bheag, the stream flows along the
strike of the rocks. In the bank on one side we have the repeatedly-
folded margin of the Limestone, on the other the white edge of the
Quartzite: the bed of the stream being formed by the Honestones,
now somewhat more siliceous, but still unmistakable. In quite a
short distance, the Honestones pass into a small group of quartzite-
bands, with a patch in the centre in which the honestone-character
is still traceable. Of these quartzite-bands, the one nearest the
limestone is quite white and almost indistinguishable from the
margin of the Quartzite; the other bands are pink and grey. When
the ground was first examined, the limestone was taken for the
Little Limestone ; for it appears to be very thin, has a bright pink
colour, and is exactly in the position where the Little Limestone
should be. The recent traverses, however, make it more probable

' See explanation of the Geological Survey l-inch map, Sheet 55 (Scotland).

Vol. 60. | OF THE EAST-CENTRAL HIGHLANDS. 435

that it is the base of the Main Limestone, which has here under-
gone one of the startling changes in appearance so often noted ;
for quite close by, and over much of the Falar area, the Main Lime-
stone has the appearance of the normal rock of Blair Atholl.

This change of the Honestones into a series of quartzite-bands of
variable colour is highly important for two reasons. In the first
place, it is obvious that these are the bands that, repeated incessantly
by folding, form the Moine Gneisses along the Sluggan Road in Inver-
cauld Forest,already described (see p. 413): the highest white band,
in particular, is especially important, for it forms the top of the
Moine Gneisses below Gilbert’s Bridge and in many other localities.
The second point is that a change in composition, similar to that
along the main line where the Moine Gneisses begin, is now taking
place in a south-easterly instead of a north-westerly direction ; in
other words, the change in composition of the rocks, due to powerful
current-actions accompanied by the deposition of more siliceous
material, is repeated to the south-east. The survey of the whole
area has shown that this tendency to revert to more sandy con-
ditions of deposition occurs again and again south-east of the Moine
Gneiss area and, though carried to a far smaller extent, it is almost
invariably accompanied by the silting-away or non-deposition of the
finer clastic material.

Beiow the type-section in Glen Mohr, the Honestones are often
exposed in the bed and sides of the gorge. A little above Falar
Burn they have an almost flinty aspect, and are characterized by
even banding, recalling a very fine phase of the Moine Gneiss
(11,125). Structurally, the rock is a very fine quartz-biotite-
granulite, but its most striking feature is the arrangement of
the crystals of brown mica. ‘Though rigidly parallel, they are
oblique to the bedding, which is clearly seen under the microscope.
Just at the mouth of Falar Burn there is a distinct increase in the
amount of originally-softer material present, and a type-specimen
(9453) could be matched from the mouth of Glen Callater. Near
the foot of Glen Mohr the whole of this softer material has dis-
appeared, and now only a thin film of the more quartzose pink-and-
grey material seperates the Main Limestone from the Quartzite. It
is obvious that there is a slight line of erosion at the base of the
Limestone, showing that it must be above the Quartzite. The pink-
aud-grey material (9406) is singularly like a portion of the Moine
Gneiss, except that it is finer in grain; and the resemblance is
equally marked in a microscopic section.

(2) The Aberdeenshire Area.

Turning now to the Aberdeenshire area, and following these finer
Parallel-Banded Rocks in a direction paraliel to that along which the
coarser Moine Gneisses have been traced, an interesting outcrop
occurs about half a mile up Allt-na-Bronn, to the east of the Bynack.
Here the quartzite is succeeded by a thin series, composed of

436 MR. G. BARROW ON THE MOINE GNEISSES | Nov. 1904,

alternations of yellow or grey quartzose laminz and films of dark
material, the whole bearing an unusual resemblance to unaltered
sediments (8522, 8523, & 8524). The grey siliceous lamine closely
resemble the typical Honestones from Glen Mohr, but as a whole they
are intermediate in composition between these and the parallel-
banded rocks at Glen Callater ; indeed, 8524 can be exactly matched
at Glen Callater. Similar material occurs in several instances in
this neighbourhood next the Quartzite, and at the head of Glen
Chonnie it is succeeded by the Little Limestone (8549). The latter
shows well the change that takes place as the Parallel-Banded
Rocks become more siliceous or the dark partings become thinner.
In place of being built up mainly of white hornblende, the
Limestone is now composed of aggregated patches or crystals of
this mineral set in a matrix of calcite, biotite, quartz, and iron-ores.
The fine dark dust is present in smaller quantity. In this part
of the district the Limestone always loses its typical aspect as
the border of the Moine Gneisses is approached, and in one case
resembles a film rich in epidote noted in the Banvie Burn (8551,
8552).

The Parailel-Banded material just described is obviously the
equivalent of the more micaceous portion of the Honestones. In the
next burn to the north (Allt Unich), the more siliceous pink-and-
grey material next the Quartzite is more persistently exposed.
Starting where the two branches of the burn join, the Quartzite and
the marginal rocks (Honestones) are well shown, the latter being
clearly the same as No. 9406 from the foot of Glen Mohr. These
rocks were obviously part of one bed of sandstone originally, and
they now fold together as one rock, and are quite inseparable.
Farther down the stream they not only become more crystalline,
but the pink-and-grey portion rapidly thickens. The burn is
obscured by Drift for a short distance, but fortunately the rocks can
be followed in the bank to the south-west ; and, returning to the
burn once more, just before the fault is reached we find the coloured
bands now so highly crystalline that a specimen (8518) taken from
a little scar at the burn-side is a typical pink-edged epidotic gneiss,
practically identical with No. 8519 taken 7 miles away from the
heart of the Moine-Gneiss area, and close to the margin of the
Cairngorm Granite. It will be noted that, in this little scar, the
low dip of the Moine Gneiss and its accompanying structures are
met with. ‘To the north-east of this point, towards Braemar and
well up the hill-side, it is evident that the Quartzite is also involved
in the movements that produced the Moine-Gneiss structure; and
this is placed beyond dispute by the distinctive pink-and-grey colour
of the marginal rock. From this burn, then, almost to Braemar, a
large portion of the Moine Gneisses are really the Quartzite, in what
may be conveniently called a ‘ Moine-phase.’

At the northern foot of Morone, rather more than 2 miles south-
west of Braemar, the Limestone and Parallel-Banded Rocks are
exposed in the face of a small scar. In this, the margin of the
Limestone is repeatedly folded on itself, and has almost the typical

Vol. 60. ] OF THE EAST-CENTRAL HIGHLANDS. 437

low dip characteristic of the Moine Gneisses in this area. Close to,
or in contact with it, is the more micaceous portion of the Hone-
stones, which are here thicker and so markedly crystalline that it is
questionable whether they are to be called Honestones or Moine
Gneisses. They contain much biotite, and the characteristic original
films of chloritic material now largely altered to biotite. These
obviously represent the softer, or more micaceous portion of the
typical Honestones that are farthest from the margin of the Quartzite.
The portion closer to the Quartzite forms the lower hill above the
road and is a highly-quartzose, more or less banded gneiss. The flat
ground at the foot of the scar between the two types of rock is
unfortunately obscured by Drift, and their relation to one another is
not at first clear. Briefly put, the doubtful Honestones, or softer
bands, are a little way within the belt of increasing crystallization,
but not sufficiently far to give them a decisive character ; the more
quartzose gneisses farther down the hill are well within the belt,
and their character is unmistakable.

At this locality, the Pink Felspathic material of the Gilbert’s-
Bridge area is again intimately associated with the Limestone and,
to a smaller extent, with the adjacent rocks; the most important
constituent of this pink material is again microcline. Further, the
softer rocks close to the Limestone are identical with the more
crystalline portions of the Honestones below Pool Tarf in the Tilt,
where, as previously stated, the further passage to Moine Gneiss is
practically unbroken.

We may conclude this account of the mode of ending-off of the
Moine Gneisses with a brief description of three sections, in all of
which the horizon of the Parallel-Banded material can be fixed just
before it becomes too thin to be shown on a map.

The first occurs about the hill of Creag-na-Dala Bige, in the
Invercauld Forest, overlooking the head of the Cairn. To the west
of this hill the Moine Gneisses cover a considerable area, although
this is largely composed of a single folded band, characterized by
pink edges and containing much epidote, already referred to. The
gneiss is succeeded to the east by a considerable mass of well-foliated
Dark Schist, here highly crystalline and containing some sillimanite,
and so much cordierite as to show that it was highly chloritic
originally, and is the lower part of the bed (8435). A few small
infolds of the Main Limestone occur within this Dark Schist. On the
opposite or eastern side of the Dark Schist, the Moine Gneisses are
represented by a small thickness of faintly-banded quartzose rock,
quite inseparable from the main Quartzite seen a little farther down
the hill.

The second occurs on the hill above Balloch, about a mile and a half
east-north-east of Invercauld House, and has been already referred
to (p. 414). The thin, faintly-banded, highly-quartzose represen-
tative of the Moine Gneisses is here succeeded directly by the Main
Limestone (9825); and there is clearly a slightly-larger hiatus than
at the locality just mentioned. A little farther west, the Parallel-

Q.J.G.8. No. 240. Qu

438 MR. G, BARROW ON THE MOINE GNEISSES _[ Nov. 1904,

Banded material is seen in the scars to have thinned away, and to
be no longer separable on a map. In this direction the Dark Schist
slowly thickens, until in a few places the full sequence may be seen.

The third section occurs about 3 miles to the south-east of
Balmoral, on the ridge north-west of Girnoch Burn. Here the
Main Limestone (9828) is often separated from the Quartzite by
quite a thin parting of dark siliceous schist, which locally thickens to a
flinty Parallel-Banded rock (9816), resembling the specimen 11,125
of the Honestones from Glen Mohr. It is, however, still more like
a flinty biotite-schist that occurs repeatedly in the corrie behind
Coldrach in Glen Clunie, but is there in contact with the Little
Limestone. The extent of the hiatus at the Girnoch ridge is
thus clearly defined ; the whole of the Dark Schist and the Little
Limestone is missing, and this is exactly the hiatus with which we
started, at Gilbert’s Bridge, 30 miles away.

Fig. 7.—Diagram showing the true succession of the rocks described.

BIGCK coc
pee
Fiintass

Meat
Limestone

Dark =
SCHUSE i. 20: ee ey Clee yee Eee
Little
Limestone =
Honestome |= * =:

=-
a
-

--—.
ms aan) meteor
eos
Ne
=-———
-—
pant en sme Fs
on fee ae et
— =. =.

Quartzite

From the evidence adduced, it will be seen that along a line more
than 30 miles long the Moine Gneisses, when traced to the south-
east, tend both to thin away and to pass into a material which was
originally of a more muddy nature. Along a considerable portion
of this line, the change is accompanied by a rapid decrease in

Vol. 60. ] OF THE EAST-CENTRAL HIGHLANDS, 439

crystallization ; and this materially increases the difficulty of ascer-
taining the mode of ending-off of thesrecognizable gneisses. When
an area of more sandy deposition is approached, there is always a
tendency for a hiatus to occur in the sequence, the Little Limestone
and part of the Dark Schist being almost always missing. Moreover,
the Dark Schist itself tends to become more siliceous and to contain
less dark dust. A similar change undoubtedly occurs in the Little
Limestone before it disappears ; but the bed is so thin that it is often
difficult to find, and its exact mode of ending-off has not been satis-
factorily determined. The hiatus is most frequently noticed at the
base of the Main Limestone, which is clearly above the Dark Schist
and the Moine Gneisses. But the missing beds were originally of
no great thickness, and are only those that lie between the base
of the Limestone and the Parallel-Banded rocks, except where the
latter were originally composed of comparatively-fine mud. Over
the whole belt of ground examined, more than 30 miles long, this
hiatus never exceeds these limits, clearly showing that it cannot
be claimed as an important stratigraphical break in the sequence
of which the Moine Gneisses form a part. Where no hiatus at all
occurs, the Parallel-Banded rocks are succeeded by the Little Lime-
stone ; and the true stratigraphical position of the Moine Gneisses
is thus defined, as lying between the Little Limestone and the
white edge of the Quartzite, of which, indeed, they are simply
the flaggy top. The succession in the group of rocks described
and their mutual relations are briefly expressed in the appended
diagram (fig. 7, p. 438).

(k) Horizon of the Gneisses north-west of the Belt along
: which they thin away.

When well across the line of thinning-away, the upper limit
of these gneisses can often be fixed ; and a few type-localities may
be selected for this purpose. One of the best lies about Derry
Lodge, where both the Limestone and the Dark Schist are present.
Close to the Derry Falls the Moine Gneisses are succeeded by a
small portion of the Dark Schist; but this is so much more
quartzose, and contains so little dark dust, that it is practically
impossible to fix its exact horizon (10,882), although the occurrence
of the Main Limestone next to it shows that this must be a repre-
sentative of part of the Dark Schist. A small quantity of the typical
felspar is present; and the rock possesses the flaser-structure so
characteristic of the Highland metamorphism. Some distance to
the south-east of Derry Lodge, a rather similar section occurs ; but
here the Limestone is associated with the Pink Felspathic material
once more (8274).

Even when no limestone is present, the upper limit of the
eneisses can be approximately fixed by the presence of identifiable
portions of the Dark Schist. Two good illustrations of this occur
in the Tarf Valley. On the south side of the stream the infold is

2u 2

440 MR. G. BARROW ON THE MOINE GNEISSES _[ Nov. 1904,

too large to leave any doubt as to its horizon; but on the north
side the infolds, which occur at the south-western foot of Sron na
Macranach, are so small that they can be identitied only by the
aid of microscopic sections. One of these (11,137) is substantially
identical with another (11,136), taken from the south-west of the
Glen-Tilt complex, and lying between the Limestone and the
Quartzite. Both he well across the belt of increasing crystal-
lization, and both contain a small quantity of sillimanite

The evidence thus shows that here and there small patches or
infolds of Dark Schist and of the Main Limestone may be found
within the main area of the Moine Gneisses ; but, as previously
explained, there is now a tendency for the Dark Schist to become
more siliceous and to contain less dark dust. so that it is difficult to
identify. But, by first studying the more siliceous phases where
the Main Limestone is present to fix their position, such as those
seen at Derry Lodge, the true horizon and meaning of these infolds
become clear.

Attention has already been drawn to the fact that a great deal
of the most highly-quartzose Moine Gneiss is simply the Central-
Highland Quartzite in a Moine-phase; and if this, as well as the
infolds just referred to, be deducted from the areas in which
the Parallel-Banded rocks occur, it is soon seen that the true
Moine Gneisses need have had no great thickness originally. The
evidence of the incessant recurrence of some easily-recognized
small band in a typical area strongly supports this idea.

(2) Slight Reversions to Similar Conditions
of Deposition.

Attention was drawn to the fact that in Glen Mohr a change in
composition in the Honestones takes place in a south-easterly
direction, on similar lines to that seen in a north-westerly, as
the main area of Moine Gneiss is approached. But the change
is more local, and not carried to the same extent. In Glen Ky,
also, the Honestones become locally more siliceous and, moreover,
are occasionally mingled with the Pink Felspathic material, evenly
disseminated through them. Similar small local changes occur in
other areas; and an excellent example occurs in Glen Loch, in the
upper part of Glen Firnate, in Perthshire. Here, on the margin
of the Quartzite, a thin band of material occurs (3838, 3839),
practically identical with that seen in the less-altered rocks of
the Unich section (Pl. XXXVI, fig. 2, No. 150). These small
reversions are of considerable importance, as they afford the
key to the phenomena of the distribution of the Parallel-Banded
material. This distribution has resulted from the natural vanning
of the detrital material brought down by a large river with many
mouths, of widely-different sizes, but all tapping a common source
at A (see fig. 8, p. 441). There must. be a series of points in
front of these streams, at which clastic material of a definite

—— ee ee

Vol. 60. ] OF THE EAST-CENTRAL HIGHLANDS. 441

texture and composition will be deposited, provided local currents
do not intervene. By joining up these points, we obtain the
line shown in the diagram. In this investigation the line

Fig. 8.—Diagram to illustrate the mode of arrangement of the areas
in which the typical flaggy Moine Gneisses now occur, and also
the origin of the film-partings, now rich in felted biotite, to which
the flaqgy aspect of the gneisses is essentially due.

[For convenience of illustration, it is assumed that the distribution of the
detritus brought down is not interfered with by other local currents.
This interference would, of course, occur, and has doubtless added to the
difficulty encountered in unravelling the meaning of the distribution of
the Moine Gneisses. |

may be taken as defining the fans of the more sandy material
from which the Moine Gneisses have been formed. The typical
areas are the larger fans; the instances of slight reversion to
similar conditions of deposition lie within the smaller ones. In
addition, the origin of the fine films of chloritic material now

442 MR. G. BARROW ON THE MOINE GNEISSES [Noy. 1904,

becomes clear. While the coarser material is deposited within
these fans in wet periods, in dry the line of deposition of finer
material would penetrate far within the fans (or towards the
shore-line), and thus the coarser material within them would
be separated by these films at more or less regular intervals.
The origin of the flaggy aspect of the typical colour-banded gneisses
is thus accounted for. In this investigation we have been dealing
with the phenomena along the margin of one of the larger fans ;
but the identity of the Moine Gneisses over large areas makes it
clear that there must be several larger fans.

Briefly, then, the Moine Gneisses are simply the flaggy
top of the Central-Highland Quartzite: this flaggy top is
restricted to certain larger fans of deposition. As we approach
the margin of each fan, the flaggy material becomes of a more
muddy nature originally ; and while the typical parallel banding
is retained, it becomes very much finer and the whole bed thinner.
It is to the fact that this change in original composition has not
been hitherto quite fully grasped, that the difficulty in accounting
for the disappearance of the gneisses is essentially due.

IV. AppEnDIxX.

A peculiar interest attaches to the easily-identified phases of the
Felspar-Rock of Gien Callater, as by means of them it can be proved
that the great masses of newer granite, shown on a geological map
of this area, have rarely produced any serious effect on the already-
metamorphosed Highland rocks. ‘The following series of slides (as
well as a number of others) was cut so as to put this fact beyond
dispute, as wellas to identify the zone in the Dark Schist.

10,777. Quarter of a mile north of Druid Farm, above Killiecrankie, and north-
west of Ben Vrackie. Perth ; 1-inch-sheet 55.
9454, Near the head of the Tilt, north of Falar. Perth; Sheet 64.

8548. Near the head of Glen Choinnich, one of the branches of the Ey Burn.
A branch of the Dee above Braemar. Aberdeen ; Sheet 64.
10,778. Glen Hy, below Aucherrie. Aberdeen ; Sheet 65.

3455. Glen Callater, just outside the Lochnagar Granite. South of Braemar.
Aberdeen ; Sheet 65.

7975. A small Sine of Dark Schist, completely enveloped in the Lochnagar
Granite. Close to the last.

The Lochnagar Granite is 10 miles in diameter, yet this inclusion
of the Felspar-Rock does not appreciably differ from any of the
others. The first specimen was taken 25 miles from this inclusion,
and there is no newer granite anywhere near it. Thus it is evident
that the great mass of the Lochnagar intrusion has produced
practically no effect on the already-altered Highland rocks.
All these specimens have been taken from the south side of the
great belt of increasing metamorphism.

On the north side of the belt similar phenomena are observed.
Here the original chloritic material is absorbed in the formation of
cordierite, but if the right portion of the Dark Schist be selected,

.
—_——_— ee ee —

Vol. 60.] OF THE EAST-CENTRAL HIGHLANDS. 443

the felspar with the dark dust is still seen to be present. A good
illustration of the failure of the newer intrusions to affect the
Highland metamorphism is afforded by the two specimens (11,137
and 11,136) selected to fix the upper limit of the Moine Gneiss.
The first is a small infold on the north side of the Tarf, and a con-
siderable distance from any granite. The second was taken near
the margin of the Glen-Tilt diorite, and forming really part of its
thin roof. The metamorphism of the two is substantially identical ;
indeed, it is not easy to obtain two rocks, so far apart, which have
so nearly the same composition, and show so exactly the same
metamorphism.

The published Geological Survey-Maps of Scotland (sheets 66 &
67) equally show that the course of the great ‘ sillimanite-aureole ’
is entirely unaffected by the Kincardineshire granite, for the aureole
meets the margin of the intrusion at right angles on its eastern
side.

Explanation of Maps and Section.

In order to understand the meaning of the maps and section
that accompany this paper, it is necessary to realize that the out-
crops here shown of such a rock as the Central-Highland Quartzite
are not the outcrops of an ordinary bed. They are really the
outcrop of a great sheet formed by the repeated folding of a bed on
itself, after the manner of the bellows of a concertina when shut up
(concertina-structure).

This concertina-structure was produced by the first and greatest
folding of the Highland rocks, and to it is due the erroneous idea
that the latter were of great thickness originally. A section drawn
across the country, after this folding was completed, would closely
resemble that drawn through a comparatively-undisturbed area,
except that the original beds have to be replaced by these horizontal
sheets. The structure has been considerably blurred, in many cases
by later movements; but over large portions of the typical ‘ Moine-
Gneiss areas,’ this sheet-structure must be still retained, for these
gneisses cover an area of several thousand square miles, and must
obviously, when viewed on a large scale, be still roughly a horizontal
sheet. ‘To the south-east of Glen Tilt these sheets have lost this
horizontality, and been thrown into anticlines and synclines that
give rise to the ridge-and-valley scenery referred to in the section
on the ‘ Succession in the Braemar Area’ (p. 423).

This type of folding, however, attains its full development only
in the harder bands, which must, moreover, have a certain thickness
before its development is possible. A perfect illustration of these
principles is afforded by the little sill of hornblende-schist shown in
the section across Glen Tilt (fig. 9, p. 444), the thickness of which
has to be greatly exaggerated to enable it to be shown. But in one
place, owing to a sudden increase in its original thickness, it was
able to fold on itself, and form a homogeneous mass 13 miles
long, and 300 yards broad at the observed outcrop, having a

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GEOLOGICAL MAP oF THE
GILBERT'S BRIDGE AREA, GLEN TILT.

Vol. 60.] MOINE GNEISSES OF THE EAST-CENTRAL HIGHLANDS. 449

thickness of at least 100 feet. Overa very large area, however,
this little sill rarely exceeds 3 feet in original thickness, and it
~ must often have been less, while its outcrop can in many cases be
crossed in a single stride. It is, of course, still repeated by folding,
but now it and the associated beds fold together as one little group,
or ‘ entity in the folding,’ together building up a sheet, and thus at
each complete fold of the group both the top and the base of the
little sill are exposed in the outcrops.

Now, just as this sill, owing to its original hardness, folds on
itself, and forms a homogeneous sheet when it thickens, so the
Honestones on the margin of the Quartzite form a similar but
larger sheet when they not only thicken to the north-west but were
composed of harder material originally. Here, however, the change
is no longer local, but is maintained over a very large area.

Later Structures.

In a typical quartzite-mountain the original isoclinal folding is
left, and this structure only is shown on the south-east side of Glen
Tilt; but as the line along which the Moine Gneisses set on is
approached a remarkable buckling structure is set up in the rocks,
conveniently known as ‘ Moine-structure,’ shown on the left of
the section. It is obviously impossible to say exactly where this
structure ends off underground.

Considerable light is again thrown on these points by the little
sill where folded on itself. Some little distance north-east of the
line of section there is a scar of hornblende-schist, and in this the
stages in the formation of the mass can be made out as follows :~

I. The sill was folded on itself to forma large mass free from
infolds of the other material (concertina-structure).

II. A fine buckling-structure, reproducing in miniature that of
the Moine Gneiss, has been superinduced on the older folding.
Specimens showing this can be easily found.

Ill. A powerful strain-cleavage was set up in the mass, and
the cleavage-planes intersect the convex faces of the minute
buckles that face the south-east. They never cut those that
face the north-west: an important fact, as showing that the
crushing movements came from the south-east. This cleavage
imparts to the rocks, at first sight, the aspect of a well-bedded
mass, with a steady south-easterly dip of some 10° to 20°; but a
careful inspection of the scar-face already referred to soon shows
how complex the structure and history of the rock-mass really is.
Thus study of this sill throws great light on the history of the
Moine Greisses, which cover so large an area to the north-west.

EXPLANATION OF PLATES XXXIII-XXXVII.
Pirate XXXII.

Map of the Gilbert’s-Bridge area, Glen Tilt. In this the principal small
outcrops of the Main Limestone are shown about the bed of the Tilt. On the
hillside above is a large mass of the same limestone, in a much purer phase,

446 MR. G. BARROW ON THE MOINE GNEISSES _[ Noy. 1904,

greatly folded. Numerous infolds of Dark Schist occur in this, but they
cannot be traced on the ground. A belt of ground to the south-east of the
main mass of the Moine Gneisses, within whiel: the passage from Moine Gneiss
to Honestone occurs, is left blank. The limit of the main mass of the Moine
Gneisses is obtained by joining up the westernmost outcrops of the Main
Limestone, which occur as small infolds. The area is typical of the whole
district ; while the stream-sections are unusually clear, the flanks of the valley
are greatly obscured by downwash and patches of Drift, and the boundaries
between the different outcrops are often uncertain.

Puate XXXIV.

[For the microphotographs from which this and the following three plates are
reproduced, I am greatly indebted to Mr. Hall, of the Geological Survey. ]

Fig. 1 (88). First cutting above Struan Railway-station, Garry area. Moine
Gneiss with typical granulite-structure. (See p. 406.)
2 (86). Bed of the Garry below Dalnacardoch Lodge. Much microcline ;
also showing quartz-bleb structure. (See p. 408.)

PLATE XXXY.

Fig. 1 (99). Gaick Forest. Inverness. Epidotic gneiss. (See p. 410.)
2 (107). Cairn Fidhleir. Tarf Area. The round-weathering oligoclase-
gneiss. (See p. 411.)

Puate XXXVI.

Fig. 1 (84). Bed of the Garry, opposite Dalnacardoch Lodge. Abundant
microcline, containing minute quartz-blebs. Green mica and a
little plagioclase. (See p. 408.)

(136). The Passage-Rocks at Auchallater, Glen Clunie, Braemar. Show-
ing the fine biotite-granulite, always present in the Honestones
or Passage-Rocks, and often their dominant constituent. (See
p- 424.)

bo

Prats XXXVII.

Fig. 1 (118). Just above the road on the west side of Braemar. Highly-
quartzose Moine Gneiss, with lines of heavy minerals (see p. 424).
This is part, probably, of the Quartzite in a ‘ Moine-phase.’ But
it is difficult to say, at this locality, where one rock begins and
the other ends: they were obviously all part of the same bed
originally.

2 (150) Sron-Dias Crags, upper part of Glen Firnate, south-east of Beinn
y Ghlo. An illustration of a slight reversion to conditions of
deposition similar to those south-east of the main area of the
Moine Gneiss, the rock on the margin of the Quartzite having
the composition and structure of a fine Moine Gneiss. (See
p. 440.)

Discussion.

Dr. Horne said that he was glad to have the opportunity of
taking part in the discussion, because he had recently visited the
sections between Blair Atholl and Braemar under the guidance of
the Author, and had the privilege of reading his manuscript now
submitted to the Society. He wished to express his high appre-
ciation of the detailed mapping done by the Author, and of his

prolonged study of the petrographical characters of the rocks of
that region.

Quart. JOURN. GEOL. Soc. VoL. LX, PL. XXXIV.

Fie... x99.

G. B. Photomicro. Bemrose, Collo.

Quart. JOURN. GEOL. Soc. VoL. LX, PL. XXXV.

G. B. Photomicro, Bemrose, Codlo.

Quart. JOURN. GEOL. Soc. VoL. LX, PL. XXXVI.

x 82.

Pia, t:

No. 84.

Fia. 2. x 82

No. 186.

Bemrose, Collo.

G. B. Photomicro.

Quart. JouRN. GEOL. Soc. VoL. LX, PL. XXXVII.

No. 1138.

Fig. O25 * $92:

G. B. Photomicro. Bemrose, Collo.

Vol. 60.] OF THE EAST-CENTRAL HIGHLANDS, 447

It is now recognized that the granulitic gneisses and mica-schists
of Moine type cover wide areas of the Highlands, from the north-
west of Sutherland and Ross to the Grampians; and it is further
admitted that they represent sediments of siliceous and argillaceous
types. The speaker believed that the first part of the paper would
form a valuable addition to our knowledge of the petrography
of the Moine Gneisses. The second part, dealing with the probable
stratigraphical horizon of these altered sediments, raised questions
of great interest and importance. Along their north-western
margin their boundary is defined by the Moine Thrust, while along
their south-eastern limit in the Grampians, where they come into
contact with the sedimentary strata of the Kastern Highlands, no such
line of disruption had been detected. He agreed with the Author
in thinking that no set of faults like that of Glen Tilt and Loch Tay
could explain the relationship, for the obvious reason that the
Moine Gneisses occur to the south-east of that line of disruption in
Perthshire and Aberdeenshire. The Author advanced the ingenious
explanation that the Moine Gneisses pass laterally into the Parallel-
Banded or Hone-Rock group of the East-Highland sequence which,
according to him, lies between the Perthshire Quartzite below and the
Little Tremolite- Limestone (or, when the latter is absent, the Blair-
Atholl Limestone) above. It had been clearly proved, as contended
by the Author, that there is decreasing crystallization of the Moine
Gneisses along their south-eastern margin, and it had been further
conclusively proved that both the Parallel-Banded series and the
Perthshire Quartzite merge into granulitic gneisses along their
junction with the Moine Gneisses. Indeed, this feature is so marked
that several members of the Geological Survey had drawn a line to
guide the colourist, but not a stratigraphical line between theMoine
Gneisses to the north and the schistose Dalradian sediments to the
south.

Regarding the section at Gilbert’s Bridge, in Glen Tilt, it was
doubtless true that a band of limestone with dark schists is there
repeatedly infolded with the Moine Gneisses, as the Author showed,
and the speaker agreed with him in thinking that it represented the
Main Limestone of Blair Atholl. Similar evidence had been obtained
in the valley of the Tarf, north of the Tilt ; while north of the Dee
the Blair-Atholl Limestone, the Dark Schist, and even the Perthshire
Quartzite, had been found within the area of the Moine Gneisses,
and infolded with the latter. The Author’s reading of the section at
Gilbert’s Bridge involved his interpretation of the East-Highland or
Dalradian sequence. But some of his colleagues had been led by
their detailed mapping to the same conclusion as that of Prof. Nicol,
namely, that the Perthshire Quartzite overlies the Black Schist with
the Little Limestone. The speaker referred to the transgression of
the Quartzite and to the evidence furnished by the Boulder-Bed at
Newbiggin, south of Braemar, where it rests upon the eroded edges
of the Parallel-Banded series, and is folded over an arch of the
Tremolite-Limestone. In the opinion of the speaker, the view that
the Quartzite is the highest member of the series, although not free

448 Mh. G. BARROW ON THE MOINE GNEISSES [ Nov. 1904,

from difficulties, was a more reasonable interpretation of the sequence
than that adopted by the Author. He therefore inferred that the
Author had not proved his main point regarding the stratigraphical
horizon of the Moine Gneisses. Indeed, he considered it improbable
that the latter were represented by a few feet, and at one locality
by a few inches of the Parallel-Banded series. The speaker then
referred to the resemblance of part of the Moine Series to the pre-
Torridonian sedimentary schists north of Loch Maree, and to the
development of structures akin to those of the Moine schists in the
basal division of the Torridon Sandstone. In conclusion, he expressed
the hope that the paper would be published with the- necessary
illustrations, as it embodied the views of one who had studied the
crystalline schists in the areas mapped by him with great energy,
enthusiasm, and ability.

Sir ArcHIBALD GeETkIx remarked that, although it had been satis-
factorily proved that the main mass of the rocks of the Central
Highlands is of sedimentary origin, great difficulties still remained
in the determination of their true order of succession. He had had
the advantage of traversing some of the Author’s ground with him
in former years, and could bear testimony to the zeal, capacity, and
ingenuity with which he attacked the complex problems which these
rocks present. The speaker, however, thought that the difficulties
involved in the Author’s present .theoretical explanation were too
formidable, and he preferred the view of the structure of the ground
which had commended itself to the rest of the members of the
Geological Survey. In the exposition of his paper given by the
Author that evening, no reference had been made to the Boulder-
Bed which formed so conspicuous a band across the Highlands,
although no doubt this band had been fully dealt with in the paper
as written. The speaker was disposed to attach great importance
to this horizon as aclue to the sequence of the formations. Yet it
illustrated some of the perplexing features of the region. Though
conspicuous along the northern margin of the central chain’ of
quartzite-ridges, it had not been recognized along the southern
margin. But, even along its line of outcrop, it appeared not to be
a continuous sheet of conglomerate; it disappeared for considerable
distances, and came in again on the same horizon, even as far as the
islands of Islay and Garvelloch. Probably it represented a series of
local shingle-beaches which were not developed farther south. The
paper would be a valuablerecord of the observations and conclusions
of one of the most active and enthusiastic among the workers who
had given their time and energy to the elucidation of Highland
geology.

Mr. Greeny felt that 1t was impossible at that late hour to deal
with the many points of great interest which were raised by this
paper, the question of the relation of the gneisses of Moine type
being one of great magnitude. In Sutherland, where the speaker
had worked, they certainly appeared to represent a very large
formation. He drew attention tothe unique opportunity for
geological science presented by the work of the Geological Survey

Vol. 60.1] OF THE EAST-CENTRAL HIGHLANDS. 449

in the Highlands. ‘Tracts of metamorphic rocks with which single
workers could deal were too small for general purposes: while the
great continental masses of them in other countries could only be
sketch-mapped during the lifetime of the present generation. In
the Scottish Highlands we had a metamorphic region large and
varied enough to be of world-wide interest and application, and yet
it could be mapped in great detail, because it was possible to bring
the united efforts of a whole staff of surveyors to bear upon it.
Herein lay the very great value of the work of the Author and his
colleagues, work which might have other applications than those of
pure science.

The Autor thanked the Fellows present for the kindly way in
which they had received his paper. With regard to the suggestion
that rocks of various ages might be involved in what may be termed
a ‘ Moine-Gneiss’ area by folding, the Author pointed out that the
newest or most recent must be older than the oldest intrusion that
cuts the folding. As an illustration of this important point, he
referred to the Meall-Gruaim ‘augen-gneiss’ shown on the map to
the south of Gilbert’s Bridge, and suggested its pre-Torridonian
age.

450 PROF. W. 8. BOULTON ON THE [Nov. 1904,

31. The Iaxnous Rocks of PonrEesrorp Hitt (Suropsurre). By
Wit1am 8. Bourton, Esq., B.Sc., A.R.C.S., F.G.S., Professor
of Geology in University College, Cardiff. (Read June 22nd,

1904.)
[Prates XXXVIII-XLIII.]
ConreEnts.
Page
I. Introduction and Previous Literature.............--scececesess: 450
II. General Structure of Pontesford Hill ...................2c.0000 452
JIT. Detaiied Description of the Rocks :—
(1) The Norther Bhyolite... S1...-- -secnseseeere eee ae 455
(2) Nodular Structure of the Northern Rhbyolite............ 457
(3) The Andesite-Group :- -

(a) The more Acid Grits and Putls) 2. 322-Gaee sedan ses- 463
(6) Palagonite-Tuffs, Grits, and Halleflintas ......... 464
(e) Andesite-Dawas. -0- 3. o-scsns es Sn eae votes mee eee ee 470
(d) Summary of the Andesite-Group ..................... 472

(4) Rhyolite-Breccias and Grits associated with the
South-Hastern Rhwyolite.2:-.).ctis-c.0c0cc.e- cae seen teak 474
(5) The South-Kastern Rhyolite. . 2.0.6: 005) .scc-ran--ceee een 476
(6) Summary of the Bedded Rocks .................-.eececees 477
(7) The: Intraswve Baste Rocks. <2 s.)2.<.cces. scene eee 478

(8) Relation of the Intrusive Basic Rocks to the Bedded
FROGIG 1. 5205 sd coals van cee ae cide se beet ee eee te etc 482
LY. General Summary of Conclusions ......25.<2-.s02---csaesccrses 482

L. InrrRopuction AND Previous LITERATURE.

PonresForD Hirt is situated on the north-western fiank of the
Longmynd range of Shropshire, about 7 miles south-west of
Shrewsbury. With a length of about a mile, and a breadth of
half a mile, it rises to a height of just over 1000 feet, and from
its summit, which is the site of a weli-preserved Roman camp, a
fine view of the surrounding country is obtained. A mile to the
west, and running through the village of Pontesbury, the Stiper-
Stones Quartzite, the local base of the Ordovician System, crops
out; while to the south-west stretches nearly the whole sweep of
the Ordovician district of Shelve and the Corndon. Immediately
to the east and south rise abruptly the conglomerates and purple
grits of the Western Longmynd, making up the conspicuous woody
ridges of Radlith and Oakswood. Between these and Pontesford
Hill is a deep and picturesque wooded gorge, cut by the Habberley
Brook. Here, about a third of a mile east of the northern end
of Pontesford Hill, is the Lyd Hole, a big, circular pot-hole, at
and near which are some conspicuous exposures of rocks referred
to by Mr. Blake and Dr, Callaway in their papers dealing with
the geology of the district. Northward stretches the great plain of
Shrewsbury and Chester.

The hill, which is nearly severed into two roughly-equal portions
by a north-eastern and south-western gulley, rises from the valley

Vol. 60. ] IGNEOUS ROCKS OF PONTESFORD HILL. 451

with abrupt and steep slopes, but with a general rounded outline. On
the north-eastern side it 1s thickly clothed with fir and larch, while on
the south-eastern flank the rocks stand out in bold, bare crags, at the
foot of which a thick deposit of coarse screes has accumulated. On
the 1-inch map of the Geological Survey the hill is marked as ‘ green-
stone, surrounded by Lingula-Flags, but for a long time rocks other
than greenstone have been known to exist in the hill. Murchison,
in his ‘ Silurian System’ 1839 (p. 264), describes the ‘ fine-grained,
crystalline. dark-coloured greenstone,’ and remarks on the previous
page: ‘ Other veined and altered rocks adhere to the north-eastern
face of Pontesford Hill.’

In 1882 some of the rocks of Pontesford Hill were recognized by
Dr. Callaway as belonging to his Uriconian Series.’

The resemblance of the banded and spherulitic rhyolites of the
northern end of the hill to the Wrekin lavas, especially to the type
of Lea Rock near Wrockwardine, is pointed out; while the pro-
nounced flow-lines in the rhyolite are said to

‘ dip to the south-south-west at 45°. . .. [The basalt] is apparently intrusive ; and
as it is not found in the neighbouring Cambrian conglomerates it is probably
post-Cambrian.’ (Op. ciz. p. 121.)

In a synopsis of the microscopic characters of the rocks
collected by Dr. Callaway, Prof. Bonney (in an appendix to the
same paper) describes a specimen of the nodular rhyolite at the
northern end of the hill and of the basalt of the camp at the
summit. (These are referred to on pp. 4597 and 479 respectively of
the present paper.)

In 1890 the Rev. J. F. Blake, in a paper dealing with the Long-
myndian and associated rocks, refers to Pontesford Hill, and says:

‘ The igneous portion of the hill consists of two masses of acid rock, everywhere
separated by a mass of basic rock..... The whole of the western slope (of
Habberley Brook), which is formed by Pontesford Hill, is occupied by well-
bedded, soft, compact, pale slate, with a moderate dip of about 30° to the west.
It is above these slates, on the higher slopes of the hill, that the igneous
rocks are met with. On the other, or western, side of the hill only part
of the slopes is occupied by a spur of decomposed basic rock; the rest of
the ground between the two masses of acid rock shows numerous exposures of
pale slates and grits of varying coarseness, with the usual high dip and strike
of the district. (Op. czt. p. 402.)

After referring to the section at Lyd’s Hole, in which he endeavours
to show that the rhyolite there is intrusive in the ‘ purple slates
and grits, which are recognized as Cambrian,’ he further says:
‘On the other, or eastern, side of the hill the slates and grits are
of a different character’ (op. cit. p. 403). In the sketch-map
accompanying Mr. Blake’s paper (pl. xvi) the hill is shown with
‘volcanic acid rocks’ to the north and south, ‘higher Cambrian

1 «The Pre-Cambrian (Archzan) Rocks of Shropshire, Part II, with Notes
on the Microscopic Structure of some of the Rocks by Prof. T. G. Bonney’
Quart. Journ. Geol. Soc. vol. xxxvili (1882) pp. 119 ez segg.

2<On the Monian & Basal Cambrian Rocks of Shropshire ’ Quart. Journ.
Geol. Soc. vol. xlvi (1890) p. 386.

452 PROF. W. S. BOULTON ON THE | Nov. 1904,

rocks’ in the middle of the hill, with ‘ volcanic basic rocks’ and
‘crystalline basic rocks’ in amongst the latter.

Thus it will be seen that Dr. Callaway regards Pontesford Hill
as made up in part of Archean rhyolite and hornstone belonging to
his Uriconian Series, with intrusive basalt of post-Cambrian age,
the whole faulted against the Shineton (Upper Cambrian) Shales,
which occupy much of the valley between the Longmynd and Stiper
Stones. Mr. Blake, on the other hand, regards the hill as made up
of slates and grits of Upper Cambrian age, with two felsites and a
basic group, all of which are intrusive in these Cambrian rocks.

My attention was first directed to the Pontesford district, when
assisting Prof. Lapworth in its mapping; and in 1890 I commenced
the detailed study of its petrology. At that time Prof. Lapworth
had ascertained that the hill is practically made up of igneous
rocks, both bedded and intrusive ; and that there are two acid and
two basic groups present, the older basic group forming an inter-
bedded part of the local, so-called ‘ Uriconian ’ volcanic group, while
the newer basic is intrusive in this older series. His microscopic
sections of some of the lower basic rocks had been identified as
palagonite-tuffs by Dr. Teall. As it appeared that most of the
lithological types of the so-called ‘ Uriconian * Series of Shropshire
exist within the limits of the hill, Prof. Lapworth urged that I
should work the petrology of its rocks in detail as types for other
Shropshire areas; and, as Pontesford Hill is isolated and circum-
scribed by faults, such a study had also this further advantage,
that it did not involve the stratigraphical relation of its rocks to
those of the neighbouring Shropshire formations.

Il. Generat Structure oF PonresFrorpD Hitt.
(Map, Pl. XXXVIII, & Sections, Pl. XX XTX.)

The hill is diamond-shaped in plan and bounded on all sides by
faults. Although, so far as 1 am aware, a boundary-fault is
actually visible at one place only (see p. 465 & fig. 3), the line of
the faults can be precisely traced: partly by the sudden change in
the slope of the ground, owing to the hard volcanic rocks of the hill
coming against the relatively-soft shales of the valley, and partly
by a line of springs, which occur at short intervals along the foot
ot the hill. Along the western flank the rocks brought down against
the Pontesford volcanic rocks are dirty-green, or pale-buff, well-
laminated, shivery shales, exposed only in very few places. In
these I have so far failed to detect fossils, but they are classed
by Dr. Callaway as Shineton (Tremadoc) Shales.* At one place
(see p. 465) these shales are seen faulted against the andesite-tuffs
and intrusive dolerite of the hill; while, in a stream-course a little
to the west, the same weathered shale is visible in situ, with loose
fragments of drifted fossiliferous Bala rock. Still farther west and

1 Quart. Journ. Geol. Soc. vol. xxxviii (1882) pp. 121, 126.

Vol. 60. ] IGNEOUS ROCKS OF PONTESFORD HILL. 453

to the north thin Coal-Measures, consisting largely of blue brick-
clays, wrap round the hill; while on the eastern side, between the
hill and Habberley Brook, no bedded rocks are visible, everything
being buried up in a thick mantle of screes from the rocks of Pontes-
ford Hill. To the north-east around Earlsdale, the tumpy nature
of the ground, and the loose, fragmental, and varied character of the
rocks, point strongly to the morainic origin of much of this ground.
Immediately to the south-west of Pontesford Hill, a narrow wooded
ridge, nearly half a mile in length, extends as far south as the
village of Habberley, made up of the intrusive amygdaloidal
dolerite of Pontesford, and apparently faulted on both sides against
the Cambrian shales of the valley.

The general trend of the hill is north and south, while the
average strike of its beds is north 30° E., south 30° W., with a high
dip towards the east-south-east. In his account of the hill already
referred to, Dr. Callaway states’ that the strike of the beds in
Pontesford is east and west, and indicates it thus on the map which
~ accompanies his paper. Further, he lays stress upon this east-and-
west (or south-east and north-west) strike of the Uriconian rocks of
Pontesford and elsewhere in Shropshire, as emphasizing a strong
discordance between them and the Longmyndian (‘ Cambrian ’)
rocks, which strike roughly north and south. As regards Pontes-
ford Hill, the dominant strike, as above stated, is not east and
west, but nearly north-north-east and south-south-west : practically
parallel, indeed, to that of the purple grits and conglomerates of
the Longmynd on the eastern side of Habberley Brook.

Running from north to south through the northern and central
part of the hill, there appears to be a fault with probably a smaller
branch-fault immediately to the west of it. Although at no point is
it possible to prove the existence of either of these faults, the surface-
features of the ground, together with the sudden displacement of
the edge of the dolerite (see map, Pl. XX XVIII), seem to demand
the existence of the larger of the two; while the sudden change of
direction of the banded structure along a definite line in the Northern
Rhyolite appears to be adequately accounted for by the smaller fault.
A small west-north-westerly cross-fault brings down the basic
group, at the extreme southern end of the hill, against the andesitic
and rhyolitic tuffs and lavas.

In carefully following single beds in the rhyolite or andesite-
group along the strike, say from south-west to north-east, numerous
small breaks are encountered, where the bed slightly but suddenly
changes its strike, generally adopting a more easterly course.
Indeed, the rocks as a whole seem to have settled down into a posi-
tion of compromise between a northerly and southerly, and north-
easterly .and south-westerly trend, and the result has been that,
while the general or average strike is nearly north-north-east
and south-south-west, the beds, owing to the slight jumps referred to,
may havea local strike nearly due north and south, or north-east and

2 Quart. Journ. Geol. Soe. vol. xxxviii (1882) p. 123 & ibid. vol. xlvii (1891)
pp. 119-22.

Q.J.G.8. No. 240. 21

454 PROF. W. S. BOULTON ON THE [| Nov. 1904,

south-west. The more easterly strike becomes more pronounced as
we pass from south-west to north-east, and therefore, as already
pointed out, it is nearly east and west in the rhyolite at the
extreme north-eastern end of the hill.

A pronounced jointing, affecting both the older bedded series and
the newer intrusive dolerite and basalt, runs from west-north-west
to east-south-east, that is, at right angles to the average strike.

The general sequence of the rock-groups in the hill, beginning
from below at the northern end, may be summarized as follows (see
sections, Pl. XX XIX) :—

A. Bedded Rocks.

(1) The Northern Rhyolite.— A pale-pink and purple
rhyolite with much epidote, chlorite, and secondary quartz, showing
vesicular, spherulitic, pyromeridal, and banded structures. Thick-
ness about 1000 feet.

(2) The Andesite-Group.—This is made up of felsitic-looking
gritty tuffs, pink and green in colour, passing up into and inter-
bedded with andesitic glassy (palagonite) and crystal-tuffs, hiille-
flintas, and lavas. Thickness about 1800 feet.

(3) Rhyolite-Breccias (glassy and crystal-tuffs) and grits.
Thickness about 150 feet.

(4) The South-Eastern Rhyolite.—Dark-red or purple
in colour, coarsely vesicular, often with bright-green and white
amygdules, and well-banded. Thickness about 250 feet.

B. Intrusive Olivine-Dolerite and Basalt, making up the
higher portions of the hill.

At the extreme north-western end the rhyolite is dipping at
about 30° south-eastward, but the banded and flaggy rhyolite a
little higher up dips 40° southward. ‘The average dip of the
andesite-tuffs and lavas is from 70° to 80°, while the South-Eastern
Rhyolite and its associated breccias and grits dip at about 85° west-
north-westward, a dip opposite to that of the rest of the bedded
rocks.

This arrangement of the beds, together with the general similarity
in composition of the acid rocks at the northern and southern ends
of the hill respectively, might suggest that the acid rocks of the
north are on the same horizon as those on the south; and that we
are dealing, either with a steep (and probably faulted) syncline, or
with the anticlinal limb of a fan-fold. But, as will appear when
these rocks are dealt with in detail, important differences exist
between the northern and southern rhyolite-rocks, and we must
regard the whole of the bedded tuffs and lavas, with the possible
exception of the Northern Rhyolite (see pp. 477 & 478), asa regular
upward succession. But whether the Northern Rhyolite is really the
stratigraphical base of the series, as would appear probable from
the evidence within the limits of Pontesford alone, or whether all
the bedded rocks, except the South-Eastern Rhyolite and breccias,

Vol. 60. | IGNEOUS ROCKS OF PONTESFORD HILL. 455

are inverted, can only be definitely determined after the entire
Uriconian and Longmyndian groups of the Longmynd, etc. have
been mapped in detail.

The bedded rocks of the hill, including the rhyolites, andesites,
and tuffs, thus have a total thickness of about 3200 feet.

All the higher portions of the hill are made up of olivine-dolerite
and basalt, that has forced its way up, mainly along two planes,
overspreading the bedded rocks, and forming a laccolite-like mass,
now separated into two parts by the north-easterly and south-
westerly cross-gulley.

Ill. Derattep Descriprion oF THE Rocks.

(1) The Northern Rhyolite.

This is typically a hard, massive, highly-siliceous rhyolite of a
pale-pink or purple colour, and showing many of the characters of
Uriconian rhyolites, which have been so admirably described by
Allport... Throughout the rock there is much yellow epidote,
green chlorite or viridite, together with calcite and secondary
quartz and chalcedony, either filling vesicles, or in veins traversing
the rock in all directions.

On the north-western flank of the hill, and in the upper part of
the mass, as far east as the larger of the two faults marked on the
map, the rock is in general well banded, with very small elongated
vesicles filled with quartz, the lines of flow running round them | (6),
The gnarled fluxion-banding is well shown at (432), where the
strike of the bands is north- east and south-west. Hast of the
smaller of the two faults, however, the banding runs nearly due
east and west, as may be well seen at (42) and (43). The dip
of these bands is 30° or less at the extreme northern end, but it
increases southward, so that at (42) it is 40°.

On the north-eastern side of the hill, nearly halfway up the
steep slope, there is an exposure of the rhyolite some 60 yards
wide, separated from the main mass by about 150 yards of dolerite.
It is hard, dense, and pink in colour, and has a brecciated look, as if
it might be a tuff. At the junction with the dolerite, the rhyolite
is considerably discoloured, and shows clear marks of having been
affected by the basic intrusion. Microscopically, this rock (559)
has a very breccia-like appearance, made up of small equal-sized
grains measuring about 0-001 inchin diameter, but without distinct
outlines. Between crossed nicols the whole mass is seen to be micro-
crystalline, with here and there angular and broken crystals of
felspar and quartz. The rock is clearly either a very fine-grained
rhyolite-tuff, or a rhyolite which has become finely brecciated

‘} “On certain Ancient & Devitrified Pitchstones from the Lower Silurian
District of Shropshire’ Quart. Journ. Geol. Soc. vol. xxxiii (1877) p. 449.

* Throughout this paper the numbers in parentheses refer to rock-specimens

and sections in the author’s Pontesford collection, the localities of the more

important of these being indicated on the map (Pl. XX XVIII).
Oi | ee

456 PROF, W. S. BOULTON ON THE [Nov. 1904,

during its movement and consolidation." From the map it will be
seen that, allowing for the displacement produced by the fault,
this outlying mass of rhyolite is in the line of strike with the upper-
most beds of banded rhyolite (43), or possibly the more acid of the
tuffs of the Andesite-Group.

A specimen (4) about 70 yards from the dolerite, of a dark
purple-red colour, and showing vesicles and white veins, has the
following microscopic characters :—The slide shows much veining
with infilings of quartz and calcite, and cavities (originally
elongated vesicles or spaces occupied by phenocrysts), which are
now filled with quartz and calcite, some of the quartz-crystals
containing needles of rutile. Patches of secondary ilmenite
altering to leucoxene occur ; while, under a high power, the matrix
is seen to be eryptocrystalline, with minute needles of felspar and
erains of magnetite. Much brown colouring-matter occurs through-
out the matrix, but especially around the filled-up cavities and
bordering the veins; it consists of minute rhombs of chalybite,
now oxidized to limonite, and in some cases hematite. Pheno-
crysts of felspar up to 0°05 inch in length are plentiful, mostly
with Carlsbad twinning, but with occasional albite-lamellation.
The abnormal quantity of calcite and oxidized chalybite, together
with the presence of ilmenite, clearly points to metasomatic
changes brought about in the rhyolite by the proximity of the
dolerite, which at one time probably covered the former. (See
p- 482.

The silica-percentage and specific gravity of the Northern Rhyolite,
together with the silica-percentage and specific gravity of the South-
Eastern rhyolite are tabulated below.” Some pre-Cambrian and
Ordovician rhyolites are included in the same table for comparison.

|

1) RE aA DW) Ve ves ria evan

ae

| i

| | |
Silica-percentage | 81:93 |'75°78 | 72:18 | 72-57 | 83802
Specific gravity ...| 2°61 | 2°63 | 9-69" | en. ! RE Wem ha ig

I. Pale-pink, finely-nodular rhyolite, northern end of Pontesford Hill.
II. Dark purple-red, compact rhyolite, south-eastern end of Pontesford
Hill.
III. Devitrified perlitic pitchstone, from the ‘Lea-Rock’ Quarry. J. A.
Phillips, Quart. Journ. Geol. Soc. vol. xxxiii (1877) p. 457.
IV. Purple quartz-felsite (pre-Cambrian), from Brithdir Farm, near Bangor.
J.J. H. Teal!, Quart. Journ. Geol. Soc. vol. xxxix (1883) p. 485.
V. Felsophyre, from the summit of Aran Mowddwy, containing porphyritic
felspar-crystals ina felsitic matrix. John Hughes, Quart. Journ. Geol.
Soe. vol. xxxi (1875) p. 400.

* Mr. John Parkinson, F.G.S., who has examined this slide, is of opinion
that the rock is a rhyolite-tuff.

* Iam indebted to Miss Maud Lightfoot, B.Sc., late of University College,
Cardiff, for the silica-percentages of some of the acid rocks of Pontesford Hill.

Vol. 60.] IGNEOUS ROCKS OF PONTESFORD HILL. 457

VI. Matrix of nodular felsite, from the Lledr Valley, near Conway-Falls
Inn. F.H. Hatch, Quart. Journ. Geol. Soc. vol. xxxix (1883) p. 489.
VII. Matrix of a nodular rhyolite, Boulay Bay (Jersey). Hyndman & Bonney,
Geol. Mag. 1896, p. 367.
VIII. Spherulite of same.

It will be seen that the rhyolites of Pontesford, especially the
Northern Rhyolite, are more acid than those of the ‘ Lea Rock’
(Shropshire) and Brithdir Farm, both of which are of reputed
pre-Cambrian age. On the other hand, they are in fair agreement
with some of the Ordovician felsites; while the mean silica-
percentage of the spherulites and matrix of the rhyolite from Boulay
Bay (Jersey), which is very similar in character to the Northern
Rhyolite of Pontesford, agrees almost exactly with that of the
South-Eastern Rhyolite. Although every care was taken in selecting
varieties as little altered as possible, it may be that the specimens
of the Pontesford rhyolites analysed contain more or less secondary
silica than some of the others quoted in the foregoing table. In
any case, without an analysis of a large number of specimens
taken from different parts of the mass in all these localities, it
would be unsafe to decide finally as to the relative acidity of these
different felsites.

(2) Nodular Structure of the Northern Rhyolite.

A very pronounced feature of the Northern Rhyolite is the
abundance of * nodules,’ which include some of the largest hitherto
described in Britain. They are nearly all confined to the centre of
the rhyolite-mass, the best specimens occurring on the north-
western slope, immediately under the Lower Camp (433), and thence
along a line to the Old Quarry (561). The diameter varies up to
8 inches or more, and there is considerable variation in their
internal appearance and structure. In this part of the rock, where
the pyromerides occur, there is practically no sign of flow-structure.

Prof. Bonney* has described the microscopic characters of a
specimen of the nodular rhyolite, from the North-End Quarry,
probably (561). He speaks of ‘hollow spherulitic concretions,
subsequently partially or wholly filled by infiltrated minerals,’ and
says that the rock of Lea Hill is very similar in structure to this
one from Pontesford Hill.

More recently, a reference has been made to the Pontesford
pyromerides by Mr. Parkinson,* who points out their strong re-
semblance to those of Wrockwardine and Boulay Bay.

Specimen 15 is a pale-pink, finely-nodular rhyolite, which,
under the microscope, shows a light-brown matrix with bright-
green and reddish-brown patches, highly coloured in places with
bright-blue ferrous sulphate. Between crossed nicols, the whole
mass is seen to be devitrified. The matrix has a spongy appearance,
* Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 124.

9

* «The Hollow Spherulites of the Yellowstone & Great Britain’ Quart.
Journ. Geol. Soe. vol. lvii (1901) p. 228.

458 PROF. W. S. BOULTON ON THE [ Nov. 1904,

with an evident perlitic structure (see Pl. XL, fig. 1). It is made
up of little bodies measuring 0-05 inch across, each consisting of
roughly-concentric arcs of glassy material, often of a bright-green
colour, alternating with crescentiform spaces, which are now filled
with clear quartz, or hght-brown dusty material. Centrally there are
often irregular or roughly-circular spaces, usually filled with clear
quartz. Sometimes the peripheral, crescentiform, glassy portions
are very irregular in shape, though retaining their sharp edges and
curvilinear outline, strongly resembling in shape the cavities
and intervening glassy matter of the Wrockwardine lthophyses
figured by Mr. Parkinson." ‘The crescentic arcs of glass above
mentioned resemble closely the vitreous splinters, with sharp,
curvilinear edges, so characteristic of the rhyolite-breccias and tufts
immediately to the north-west of the South-Eastern Rhyolite (see
p. 475 & Pl. XLIIT, fig. 4). In common with these, they often
show the characteristic longitudinal tension-lines in the glass, as if
formed by its distension; but these might be explained by con-
traction during the development of the perlitic structure.

It seems possible that some of these small bodies represent
vesicles (lithophyses), similar in structure to the much larger
vesicle in artificial slag shortly to be described (fig. 2, p. 461),
and now filled with secondary quartz. At the same time, it is
clear that the structure of the matrix is largely perlitic, much of
the original glass having been replaced by silica, the remaining
devitrified portions (green and brown in colour) showing the charac-
teristic outlines of the perlitic structure.”

Prof. Bonney, in describing the nodular felsites of North Wales,’
holds that the nodular structure has been produced
‘by simple contraction and roughly-concentric cracking of the mass in cooling,
being thus intermediate between the perlitic structure common in glassy acid

lavas and the spheroidal structure common in basalt...’ or ‘by similar con-
traction in cooling, which is determined by the presence of a cavity.’

It may be that the matrix of this Pontesford rock with perlitic
structure, and what appears in places as a microlithophysal structure
as well, owes its finely-nodular character to the causes referred
to by Prof. Bonney.

The nodules proper in this specimen (15) are quite small (0-1 to
0-3 inch) and usually imperfect and irregular. ach consists of a
fibrous growth, in some cases, apparently, round one or more
vesicles; but in the absence of flow-lines curving round them, or
other direct evidence of the gaseous origin of the cavities, it is
possible that these cavities may have been occupied originally by
spherulitic growths. Into these cavities, and around them, the
brown fibrous material has developed, forming tufted or mushroom-
shaped growths. The same fibrous material has finally surrounded

* Quart. Journ. Geol. Soe. vol. Ivii (1901) p. 221.

~ 'T. G. Bonney & J. Parkinson ‘On Primary & Secondary Devitrification
in Glassy Igneous Rocks’ Quart. Journ. Geol. Soe. vol. lix (1903) p. 440.

% Quart. Journ. Geol. Soe. vol. xxxviii (1882) p. 295.

Vol. 60.) IGNEOUS ROCKS OF PONTESFORD HILL. 459

the whole mass, though often very imperfectly. In the brown
fibres are many circular clearer spaces, which were originally
spherulites (in some cases possibly vesicles) with the brown fibres
crossing them, but now filled with a mosaic of irregularly-outlined
quartz-crystals. The brown fibrous growth is by no means confined
to the nodules: it occurs sporadically in small and often quite
irregular patches anywhere in the perlitic, and what I have termed
the microlithophysal, matrix. But usually it seems to have started
to develop along a definite line, such as a crack,‘ or the edge of a
vesicle or crystal, and then gradually spread, fungus-like, through
the surrounding material.

The following descriptions are from slides kindly lent to me by
Mr. Parkinson :—

(a) Pyromeridal nodule from the north-west of the hill, about
1-3 inch across, with a roughly-oval cavity filled with quartz and
pale-brown angular chips, and with a double fractured border of
yellowish and reddish-brown fibrous material (Pl. XLI, fig. 1).
Under the microscope, the matrix, in which the nodule is em-
bedded, is greenish and yellow-brown, and much stained with iron-
oxide, and it shows in polarized light a microcrystalline aggregate
largely made up of secondary quartz-grains. The wall or border
of the nodule is much fractured and veined with secondary silica,
while angular, broken portions of the wall appear towards the
centre of the amygdaloid. This border is made up of the usual
brown microfelsitic fibrous matter, often in radiating tufts, and
spreading out into mushroom-like growths, where it has had a free
space in which to develop. Groups of felspar-phenocrysts or
isolated individuals, showing simple or albite-twinning, occur in
the fibrous border; and the fibres are usually deflected round the
crystals, and not infrequently radiate outward from their walls.
The cavity is now filled with a mosaic of clear quartz-grains,
enclosing small brown spherules, generally with a well-marked
radial structure, and showing the black cross in polarized light.
Usually, these spherulitic bodies are surrounded by a border of
perfectly-clear quartz, the smaller ones by perfect little hexagons
of quartz. Often chalcedonic silica is arranged in agate-like bands.

(>) Another nodule from the same locality, about 1°5 inch long,
contains an irregular quartz-amygdaloid, and shows a much-
fractured border, looking, indeed, as if the fracturing occurred when
the nodule was hollow (Pl. XL, fig. 2). Under the microscope,
many felspar-crystals, some 0:1 inch long, are seen in the fibrous
border, and the material of the latter is often arranged in radial
bunches, like that of the spherulitic bodies of the Lea Rock. The
central cavity is now filled with a brightly-polarizing mosaic of quartz,
in which are crowds of small brown spherules, with a pronounced
radial structure and showing the usual black cross with crossed
nicols. Lining the inside of the surrounding fibrous border is a
thin band of clear silica, and then a layer of the small, brown,

There is, of course, the possibility that, in some cases, such cracks are the
result of contraction due to the crystallization of the fibrous material.

460 PROF, W. S. BOULTON ON THE [ Nov. 1904,

spherulitic bodies, while these latter are sometimes arranged in
bunches radiating from the wall of the amygdaloid towards its
centre. It is clear that the brecciation of the wall of the nodule
occurred before the infilling of this silica and brown spherulitic
matter, for they are arranged in concentric borders around the
angular and isolated fragments of the wall.

Fig. 1 is a sketch of a nodule 7 inches across, collected by myself
from locality (433). There appear to be three generations, as it were,

Fig. 1.—Sketch of a nodule of complex structure,
measuring 7 inches across.

I @ \ ve)

A= Fibrous border,
B=Quartz-amygdaloid.
C=Quartz and brown spherulites.

in the formation of this nodule. Fibrous borders have been formed
apparently around two small vesicles; one nodule thus formed,
containing a more or less rounded amygdaloid, has become partly
enveloped by a larger, including an irregularly-stellate quartz-
amygdaloid, while all three have been enveloped in a dark-brown
fibrous layer, which forms the outer wall of the nodule.

A specimen of slag given to me some years ago by Mr. H. T. Waller
is interesting in this connection, and seems to have some bearing
upon the origin of these pyromeridal and lithophysal structures. It
is a compound vesicle or lithophyse, 14 inches across, in a bluish-
grey glassy slag (fig. 2, p. 461). The main vesicle is surrounded by
roughly-concentric ares of light-brown transparent glass, and be-
tween these glassy layers are crescentiform spaces. If this structure
occurred ina rhyolite, if the glass then devitrified, and brown fibro-
radiate microfelsitic matter developed in and around it, and the

Vol. 60.) ° IGNEOUS ROCKS OF PONTESFORD HILI. 461

empty spaces subsequently filled with quartz, we should get a very
close resemblance to some of the nodules that are found in the
ancient rhyolites of Pontesford and elsewhere.’

Without entering, for the present, into a further detailed account
of these pyromeridal structures, the general conclusions so far arrived
at may be thus briefly summarized. In many cases, though
certainly not in all, the nodule appears to have commenced as
a vesicle, often irregular in shape, and sometimes, possibly, with

Fig. 2.—Complex vesicle in artificial slag. (Natural size.)

crescentiform spaces around the main cavity, and separated from it
by similarly-shaped portions of the glass. Such vesicles probably
occur, on a very small scale, in the matrix of the rhyolite, and
show little or no further change, beyond the infilling of the
cavities with quartz and other secondary minerals, the fracturing
and deformation of their walls by subsequent movements of the

* There is a striking similarity between this lithophyse in slag and many of
those in the rocks of Obsidian Cliff described by Prof. J. P, Iddings, 7th Aun.
Rep. U.S. Geol. Surv. 1885-86 (1888) pp. 265 e¢ segg. It should be noted that
while this vesicle occurs at the surface of the slag, and was due solely to
the rapid distension and cooling of the slaggy magma, the lithophyses of
Obsidian Cliff, and of the ancient rhyolites of Pontesford, Boulay Bay, etc., are
in the body of the rock, and may have been produced, in some cases, by the
progressive crystallization in a ‘hydrous patch,’ as explained by Prof. Iddings
and Mr. Parkinson.

462 _ PROF. W. S. BOULTON ON THE [ Nov. 1904,

mass, and, in some cases, a slight development of the brown fibrous
material. But, in the case of the larger cavities, the brown fibrous
growth has developed conspicuously, encroaching upon the cavity,
as well as the surrounding matrix, evidently in much the same way
as in the admirably-described cases of the much smaller lithophyses
of the obsidian of the Rocche Rosse, Lipari. Thus, fibrous,
radiating, or mushroom-shaped masses can frequently be seen
penetrating the ‘vesicle,’ now filled with quartz, and spreading
across smaller cavities in the surrounding matrix. This fibrous
growth starts in general from the wall of the vesicle or cavity, but
it may develop from other lines or points. Thus felspar-phenccrysts,
which appear to be more numerous in the vicinity of the vesicles
than elsewhere, frequently form the centres for radiating growths,
which, by their coalescence, help to form the boundary-wall of a
nodule. Possibly, some of the vesicles, with their borders of brown
fibrous and often spherulitic matter, remained empty for a long
time, for the wall is often much fractured, angular fragments of it
occurring in the cavity, and now surrounded by concentric layers
of quartz and brown dusty or fibrous felspathic or microfelsitic
matter, usually with a well-marked spherulitie structure. Thus
the fibrous growth probably represents a phase of
the early devitrification of the glass, while the quartz,
chalcedony, and brown spherulitic aggregates were
introduced subsequently. Indeed, some of this fibrous matter
may represent the original crystallization of the magma during
cooling, rather than the devitrification of solidified glass.” At the
same time, it would seem that the formation of the fibrous material
is not confined to one stage in the process of devitrification, for,
as already remarked, it is found traversing old spherulites, now
occupied by secondary quartz.

There seems to be no limit to the size of such nodules,
for the fibrous material may successively surround smaller
individuals, producing composite nodules, of which the smaller
constituents may be of true lithophysal origin, their amygdaloids or
filled-up vesicles having a definite relation to their boundary-walls :
while the outer enveloping walls have no such related amygdaloids,
but, instead, smaller nodules which have played the part of vesicles
or phenocrysts in inducing devitrification in the form of a fibrous
layer.

Nevertheless, it is clear, from a study of the Pontesford nodules,
that some are quite solid to the core, without any quartz-amyg-
daloid, and with a more or less irregular, radial-fibrous structure.
These may be looked upon as imperfect spherulites or ‘skeleton-
spherulites,’ that probably commenced to develop from the centre
outward, as in the ordinary type of small spherulite. Further,
it would be rash to deny that in some cases the centres of these

’ G. A. J. Cole & G. W. Butler ‘On the Lithophyses in the Obsidian of
the Roeche Rosse, Lipari’ Quart. Journ. Geol. Soe. vol. xlviii (1892) p. 438.

2 See J. Parkinson ‘Some Igneous Rocks in North Pembrokeshire’ Quart.
Journ. Geol. Soe. vol. liii (1897) pp. 469-71.

Vol. 60.] IGNEOUS ROCKS OF PONTESFORD HILL. 463

once solid spherulites (as contended by Prof. Cole and Mr. Harker) *
have been destroyed, and replaced by secondary mineral matter,
generally quartz, which now forms the so-called amygdaloid.
If the mass is coarsely vesicular or lithophysal, there will be a
strong tendency for the fibres to surround these cavities, extending
outward into the matrix and inward towards the centre of the
vesicle. Similarly, fibrous matter may develop radially outward
from phenocrysts, or, as in ordinary spherulites, from central
points or lines, where the conditions have been such as to induce
erystallization.

It would seem, then, that many of the nodules are spherulitic
growths, where the spherulitic fibres develop in general, not from
a central point outward, as in the small, true spherulites, but
locally from vesicles or other cavities, crystals, etc., coalescing finally
to form in some cases larger and larger growths. Those nodules
which have roughly-concentric or crescent-shaped cavities, now filled
with quartz, may be due in some cases to a progressive or ‘ spas-
modic’ crystallization of a ‘hydrous patch’ during the solidification
of the rhyolite-magma (see p. 461). But in other cases, they may
have arisen as compound vesicles, due to the local distension of the
magma, and the subsequent development of the brown, fibrous and
spherulitic material. The spherulitic type of devitrification is not all
of the same age, for fibrous growths undoubtedly traverse small
and earlier-formed spherulites, which have been dissolved out and
replaced by quartz.

In a specimen of the South-Eastern Rhyolite, a spherulitic growth
has taken place around an undoubted vesicle, now filled with
quartz, for the flow-lines can be seen distinctly curving round it.

(3) The Andesite-Group.

(a) The more Acid Grits and Tuffs.—The actual junction
of the Northern Rhyolite and the succeeding tuffs is not seen, but
the felsitic-looking grits and tuffs follow on immediately, the line of
junction being marked by a hollow in the ground with springs. No
reliable dip in these basement-tuffs can be made out, but when a
good dip is seen higher up in the andesite-series, the beds are
dipping at about 80°. These acid-looking tuffs crop out along the
road and lower skirts of the hill (537, 566, 556, 555, 554, 553, 552,
551). They are pink and green, fine-grained, gritty tufts, with a
distinctly-acid look, though containing very few quartz-grains.

No. 566 is a fine-grained grit, the grains being pink, set in a
greenish matrix. Under the microscope the grains, measuring up
to 0°04 inch across, are seen to consist of lapilli of vesicular,
devitrified glass with well-marked fluxion-banding, together with
broken crystals of felspar with lamellar twinning. One fragment,
0°05 inch across, contains skeleton-crystals of orthoclase in a de-
composed greenish glassy matrix, a few subangular quartz-grains,

' G, A. J. Cole, Geol. Mag. 1877, p. 299; A. Harker, ‘The Bala Volcanic
Series of Caernarvonshire’ [Sedgwick Prize Essay for 1888] 1889, pp. 28-40.

464 PROF. W. S. BOULTON ON THE [ Nov. 1904,

and some secondary silica. The rock is undoubtedly a tuff, and
from the abundance of simply-twinned felspar, and the felsitic
look of the lapilli, apparently more acid than the andesite-tuffs
higher up.

No, 554.—A dull-green and red ashy-looking rock, with
55°8 per cent. of silica and a specific gravity of 2-694. Micro-
scopically, it is clearly a fine ash with lapilli measuring up to 0°05
inch across, made up mostly of decomposed glass with skeleton-
crystals and microlites of felspar, most with simple twinning, but
some (one 0:05 inch long) showing jamellar twinning. ‘The rock is
rather more basic-looking than No. 566, aud the fragments are
much stained with iron-oxide.

No. 551, of pinkish colour, much-jointed, fine-grained, weathering
a dull green, is exposed at the back of a ruined cottage, near the
road. (Silica-percentage = 57°07; specific gravity =2°57.) Under
the microscope, it is seen to be a very fine-grained tuff, made up
largely of broken crystals of felspar with simple and lamellar
twinning (0-001 inch or less), minute particles of reddish-brown
glass, with sharp edges and curvilinear outlines, and containing
minute vesicles, together with very few quartz-grains.

All these tuffs and grits clearly belong to the Andesite-Group,
for they pass at once without a break into the typical palagonite-
tuffs, and indeed are interbedded to some extent with them. From
their colour and texture and lower specific gravity, one is tempted
to class them with the rhyolite as a group of felsite-tuffs, rather
than with the andesites; but they contain, on an average, only
about 5 per cent. more silica than the palagonite-tuffs, and their
microscopic characters are practically the same as those of many of
the andesite-tuffs higher up the series. It may be here remarked
that many of the small pink chips and lapilli in these tuffs, of a
pronounced rhyolitic or felsitic appearance in the hand-specimen,
generally show under the microscope precisely the same characters
as those in the tuffs which, on analysis, prove to be of andesitic
composition. The felsitic appearance is doubtless due, in part, to
the smallness of the grains allowing of the complete oxidation of
the iron to the ferric state.

(6) Palagonite-Tuffs, Grits, and Halleflintas.—Behind
the cottage at the top of the road leading to Pontesbury (201 on
the map, Pl. XXXVIII) occurs an interesting exposure, showing
the newer basic rocks penetrating the tufts, and both faulted against
the buff-green shivery Shineton Shales, that abut against the hill
(see fig. 3, p. 465). Here (201 a, 6, ¢, d, «) we get, for the first
time, the palagonite-tutts of the Andesite-Group. ‘They are dull-
green, bluish when fresh, but weathering yellowish-green, and fine-
grained with white flecks.

No. 201 a consists of irregular fragments of yellow and greenish-
yellow decomposed glass measuring up to 0:04 inch across, including
small round vesicles and minute felspar-microlites, and with curved,

Cambrian,

.
Vol.60.] © | IGNEOUS ROCKS OF PONTESFORD HILL. 465

sharp outlines, set in a matrix of very fine glassy dust, containing
in places much secondary calcite. The lapilli of palagonitized glass,
often covered with minute brown pigment-spots, like spots on a
leopard’s skin, show no reaction with crossed nicols. The round
vesicles have a clear transparent border of a doubly-refracting
zeolite, and a faintly-polarizing substance in the centre, while many
elongated vesicles have a yellow border of palagonite, and enclose a
colourless zeolite in the centre. Broken crystals of felspar, measur-
ing up to 0:02 inch, occur, as also occasional angular grains of
quartz.

Fig. 3.—Sketch-map showing Pontesford rocks faulted against
Cambrian shales, at the top of the road leading to Pontesbury
[ 207}.

Palagonite-Tuffs. Intrusive Dolerite. Tuffs.
eC e,

Y lan Py eas 2 ee

[Scale: 1 inch=about 20 feet. ]

No. 2016, though occurring quite close to 201 a, is very different
in colour and texture. It is made up of lapilli of yellowish-green
vesicular palagonite and crystal-fragments. A fragment of brown
glass (0°0025 inch) contains minute needles of felspar and larger
laths of the same mineral showing distinct lamellar twinning,
together with small green patches that may be decomposed pyroxene.
Lapilli, measuring up to 0-1 inch across, vesicular, slaggy, and
twisted, are common, with some secondary calcite in the matrix.

No. 201d is harder, and paler in colour with pink and green
flecks, and contains lapilli of greenish andesite-glass with minute
black vesicles. Microscopically, it shows good felspar-crystals,

466 PROF. W. S. BOULTON ON THE | Nov. 1904,

measuring up to 0°05 inch across, with simple and lamellar
twinning, and an extinction-angle up to 16°.

No. 2U1® is a buff rock with pink grains, which microscopically
shows decomposed glassy particles and many broken crystals of
felspar (0°05 inch), parts of short rectangular prisms with albite-
lamellation. A lapillus, 0-03 inch across, is much stained with
red iron-oxide and is crowded with minute felspar-laths.

In among these tuffs the coarsely-amygdaloidal intrusive dolerite
has made its way. No. 201 is a fine-grained, granulitie dolerite
with serpentinized olivine-phenocrysts, 1n general character similar
to No. 28, described on p. 481. No. 201 y is a somewhat doubtful
rock. Itis dull yellowish-green, fine-grained, with green needles and
larger greenish-black patches with a dull pitchy lustre, made up of
a soft substance which is greenish-yellow when scratched—probably
palagonite. Microscopically, it is of uneven texture and colour,
with small laths of cloudy plagioclase, milk-white in reflected light,
oceurring ophitically with pale-green, much-cracked augite, altering
to a dark-green chloritic mineral. There isa good deal of pale-green
and yellow substance,, with cracks that suggest olivine, and red,
slightly-pleochroic depositsin small flakes and needles along the cracks.
The description of this rock would seem to apply equally well to
the ophitie dolerite with serpentinized olivine, and the andesite-lava
with patches of palagonitized glass. On the whole I am inclined to
put it in the latter group (see p. 471).

At (434), in a small opening near the road, is a dull purplish-
red, fine-grained rock, which, microscopically, is seen to be much
stained yellow, brown, and black, and made up of minute angular
chips of felsite and quartz, in a fine brown dust. Fragments
measuring 0-1 inch across, composed of these chips, are embedded
in a matrix of the same material, with crystals in nests or clusters,
the whole showing traces of bedding. ‘This rock is distinctly more
acid-looking than the palagonite-tuffs just described, and shows a
temporary return to the more acid type which follows the Northern
Rhyolite.

A conspicuous crag on the south-west of the gulley, referred to
as ‘ Agglomerate-Crag’ in my field-notes, is made up of a coarse
andesite-agglomerate or tuff, but very varied in colour and texture.
Some parts consist of yellowish-green palagonite-tuff with minute
angular dark-grey patches, with a flaggy and slightly-schistose struc-
ture, crumbling readily when struck with a hammer, others being of
harder, fine-grained, pink and green, gritty tuff; or again extremely
fine-grained, purple, yellow, or green hilleflinta. Angular fragments,
sometimes several inches across, of purple amygdaloidal andesite,
often showing most pronounced fluxion-banding, are embedded in a
green or pink, fine-grained matrix. The entire crag is much
jointed, the fragments showing elaborate faulting on a small scale,
and epidote and chlorite are common as secondary products.
Immediately behind the main crag, the tuff, with banded and
vesicular purple andesite-lapilli, embedded in a fine matrix of the

Vol. 60.] | IGNEOUS ROCKS OF PONTESFORD HILL. 467

same material, is well seen; while to the south-east of it is a bright-
yellow, hard, and exceedingly fine-grained hialleflinta, 2 feet thick,
which can be traced along the hillside for many yards, thus accu-
rately fixing the strike.

The followmg examples show the more typical microscopic
characters of these rocks :—

(Agg. Crag, a.)—Red and green gritty tuff, with fragments
measuring. up to 0:2 inch across, of decomposed glass, crowded with
minute round vesicles, now filled with pale-green doubly-refracting
zeolite, together with microlites of felspar showing very low ex-
tinction-angles; crystals of felspar, partly broken, measuring up to
0-04 inch, with good lamellar twinning; occasional angular grains
of quartz ; twisted pieces of vesicular glass; lapilli of previously-
consolidated glassy tuff, one being made up of a granular bright-green
matrix, full of minute felspar-laths with a parallel arrangement.

(Agg. Crag, b.)—A good specimen of palagonite-tuff, with lapilli
of reddish-brown and bright orange-yellow palagonite (pale-yellow
by incident light) of curvilinear outline, and crowded with minute
felspar-laths, and vesicles which are as a rule perfectly circular, but
sometimes much elongated. These have usually a ring of clear
doubly-refracting zeolite, with a similar material, or, in some cases,
a yellow isotropic substance, in the centre. Some amygdules show a
black cross with polarized light; and there is much dirty-white
ealcite in the matrix. (Pl. XLII, fig. 2.)

(Agg. Crag, c.)—Shows a fragment, 0°75 inch across, with fine
red and green bands, embedded in a matrix of pink and green
grains. This matrix is a fine crystal-tuff, made up of broken
erystals of plagioclase with repeated twinning, pinkish-brown in
colour, and set in a fine green dust, while the lapillus consists of
alternating bands of purplish-red dust and crystal-fragments.

(Agg. Crag, d.)—A green tuff, with dull green and pinkish-brown
lapili measuring upwards of 0°75 inch across. These consist of
black glass with felspar-microlites; pale-red, altered glass with
many round vesicles filled with a green substance, one pear-shaped
fragment of glass 0-06 inch long showing marked perlitic structure.

No. 205—near Agglomerate Crag—is a coarse, pink-and-green
gritty tuff, showing well all the different kinds of lapilli, which
measure generally about 0-1 inch across (Pl. XLII, fig. 1). An
included fragment in the tuff, of a pale yellowish-green, is a piece of
decomposed andesite-lava, the matrix being crowded with felspar-
needles, milky-white by incident light, and containing vesicles filled
with pale yellowish-green, doubly-refracting zeolite with spherulitic
structure.

A buff-yellow finely-laminated hilleflinta,’ near by, shows bands
of very fine glassy dust, alternating with coarser bands made up of

| The term ‘halleflinta’ is here used, as elsewhere in this paper, as a general
field-term for a hard, felsitic, fine-grained, laminated rock. In Pontesford
Hill all the halleflintas are fine glassy and crystal-tuffs of andesitie com-
position.

468 PROF. W. 8. BOULTON ON THE [Nov. 1904,

erystal-fragments, and splinters of yellow palagonite enclesing
felspar-needles (Pl. XLITI, fig. 3).

These rocks can be easily followed cropping out along the south-
western face of the gulley, but higher up the slope towards the
wood at the top of this part of the hill, the beds are found to be
harder, more massive and fine-grained, less flaggy and niore gritty,
until at the top near the wood (512) the rock is a very hard
massive grit, dark green with pink grains, having a specific gravity
of 2:79, and dipping at 80°. Microscopically, it resembles No. 205,
but is not so coarse, and contains many grains of ilmenite altering
to leucoxene, a constituent which probably accounts for its rather
high density.

A band of these hard grits, 70 yards thick, can be traced all
down the north-eastern slope of the gulley, dipping about halfway
down at 60°. They are followed at once on the south side by
beautifully-laminated green and yellow hialleflintas, with inter-
bedded andesite-lavas ; while on the other, or north-west, side they
are covered by the newer basic rocks.

Some of the best and most accessible spots for observing the
typical andesite-rocks are along the foot of the western slope of
the hill, south of the gulley, in the little gardens behind the cottages
that occur at intervals along the road. Thus at (209) the foilowing
section is seen :—

Fig. 4.—Section under the fence, western flank of
Pontesford Hill {209}.

“SS QA SS Ss

WN SS S SON MW
ma . AX WAN SS SS ve

{Length of section = about 30 feet; dip = 85°.]

a=Finely-laminated green hilieflintas, 8 feet thick, striking obliquely with
the fence and dipping at 85°, containing a red and white siliceous band
12 inches thick (4), which, under the microscope (530), appears to be a
tuff-band with broken felspar-crystals, but very largely replaced by a
mosaic of secondary guartz- -crystals.

c—A coarser, andesite- tuff with circular, oval, and subangular lapilli of ande-
site- glass, 2 or more inches across; and interbedded with beautifully
banded red, blue, and yellow hilleflinta.

The lapilli of andesite-glass occur also in the fine halleflinta, the
lines of which flow round them, showing some resemblance to a
finely-banded lava with phenocrysts. A lapillus of andesite (531),
taken from the finely-banded tufts, shows microscopically an andesite-
glass, pale yellowish-white by reflected light, containing Jaths of
felspar 0-05 inch long, often in radiating groups, much decomposed,
but some showing lamellar twinning. Crystals of a pyroxene-like
mineral, now replaced by a yellowish-green product, have evidently

Vol. 60.] © | IGNEOUS ROCKS OF PONTESFORD HILL. 469

erystallized out after the felspars, for they often enclose the latter.
Irregular, but rounded portions, which macroscopically might be
taken for filled-up vesicles, are found to be fragments of previously-
consolidated palagonite-tuff, with minute angular bits of palagoni-
tized vesicular glass, enclosing needles of felspar, and occasional
crystals of augite. These fragments of tuff embedded in the lava
have been partly re-fused: for, although of irregular shape, their
edges are quite rounded.

Along the same line (305, 308) are very typical examples of the
palagonite-tuff. In (3505) angular lapilli, measuring up to 0°15 inch
across, of green and orange-coloured palagonitized glass are present,
containing abundant circular vesicles filled with zeolites, together
with minute needles of felspar. Many of these lapilli have amarkedly-
twisted and slaggy appearance, and some are strongly stained with
iron-oxide. The matrix of the rock is a very fine dust, now largely
replaced by calcite and other secondary minerals. (Pl. XLII, fig 3.)

Ascending the hill from the gulley towards the Higher Camp on
the main summit, the andesite-lavas, coarse and fine andesite- and
palagonite-tuffs, with hialleflintas, are met with in many isolated
crags, all along the north- western and western face, extending half-
Way, in some places two-thirds of the way, up the slope, where they
are covered irregularly by the basic rocks (520, 522, 523, 524, 525,
etc.). These tuffs are of types already described, but the finer tuffs or
halleflintas are hereabouts more common, and are especially well-
displayed at intervals along the lower slope, where crags showing
beautiful lamination may be seen, as well as quantities of hiilleflinta-
débris brought to the surface by rabbits.

The following is a complete analysis of palagonite-tuff from
Agglomerate Crag, by Dr. C. F. Baker, late of the University of
Birmingham :—

Per cent.
a nthe ert Beacia fag 53°41
LUE SR Re tae eee Re. 11°52
i Ea) eee eal Coxe canopy apa TE Sa sine i 8:36
1 oS gla li SAUER ERE eae SR aera H 3°38
Bess Ce) ee sy 1-48
Oe eee do, Hee Sh Bn at 13:16
0 EE a eee ie ee oot 2°63
__# 3 tiger opted are argo 0-63
RR ee ose oo eee ee re O71
Loss at about 110° Centigrade ... 1°54
Loss, extra, at dull-red heat ...... 3°56
(Specific gravity = 2-743.) 100°38

Sir John Murray & the late Prof. Renard,’ in comparing an
analysis of palagonitic matter with that of the anhydrous silicate
(basic glass), from which the palagonitic substance was derived, say :

‘The transformation which has taken place seems to tend to the formation
of a zeolitic substance ; lime and magnesia are eliminated, the protoxide of iron

* Challenger Reports: ‘ Deep-Sea Deposits’ (1891) p. 307.
Q.J.G.8. No. 240. 2k

470 PROF. W. S. BOULTON ON THE [ Nov. 1904,

passes into peroxide, alkalies derived from the action of sea-water enter into
combination, the quantity of alumina remaining almost constant.’

In the palagonite-tuff of Pontesford most of the iron is in the
peroxide-state, while the percentage of lime is high, and magnesia
low. It must be remembered that the rock contains a fair amount
of secondary calcite, so that both original lime and magnesia may
have been removed from the glass during the formation of pala-
gonite. It would be difficult, or impossible, however, to demonstrate
these changes in a tuff with secondary deposits (calcite and zeolites)
in the matrix, as is the case with this Pontesford specimen.

(c) Andesite-Lavas.—The andesite-lava, which, as already
noted, occurs as lapilli in the tuffs, is also found interbedded with the
tufts, though covering a relatively-small area. It has been found very
difficult, in the field, to separate some of these andesite-lavas from the
newer basic rocks, for both may be fine-grained, with a dull blue- or
grey-greenish colour. Typically, however, the andesite is bluish-
green, weathering yellowish-green, fine-grained, with small white, and
often squat-shaped, felspars, easily recognized with a lens, and small
soft black specks, giving greenish scratches, which under the micro-
scope are found to be portions of the interstitial glassy matrix con-
verted into palagonite, together with vesicles filled with a chloritic
substance ; while the compact varieties of the intrusive dolerite
usually weather reddish-brown, and the felspars are less prominent.
Where the andesite occurs near to the intrusive dolerite (and indeed
it is never far from it) it is often darker than usual, owing, as
microscopic examination shows, to the development of large numbers
of minute magnetite- or ilmenite-grains, so that it becomes increas-
ingly difficult to distinguish it from the finer dolerite. Moreover,
there is always the possibility of the dolerite showing through among
the andesite-lavas, as, indeed, it actually does in one or two places
(516d). The difficulty of separating these rocks does not completely
disappear when a microscopic examination is made: for, as will
appear in the following descriptions, many of the mineralogical and
structural characters are common to some specimens in both groups.
By slicing a large number of rocks at all the doubtful points, and
repeatedly noting their field-relations in the light of the knowledge
obtained from an examination of these rock-sections, it has been
found possible to distinguish the two groups, and map their
boundaries with tolerable accuracy.

At the south-western end of the gulley, at the foot of the northern
face and opposite ‘ Agglomerate-Crag,’ is a typical specimen of
the andesite-lava (57), interbedded with green-and-yellow finely-
laminated hilleflinta ; and a few yards to the west (516) is a group
of crags showing two similar thin beds of lava (5164, 516¢), a few
yards wide, separated by relatively-soft green palagonite-tuff (516 5),
while a small sill of intrusive dolerite abuts against 516c. The
same lavas are seen in among the hiilleflintas and palagonite-tuffs
all along the lower slope of this part of the hill, and up to the line
of the intrusive dolerite (525, etc.).

Vol. 60. | ' IGNEOUS ROCKS OF PONTESFORD HILL, 471

Under the microscope, the andesite-lava (516c, 57 a) is found to be
made up of a felted mass of felspar-laths about 0:02 inch in length,
milky-white by reflected light, but still showing both simple and
lamellar twinning, generally extinguishing parallel to their length,
or nearly so, indicating a felspar of the oligoclase-series. A good
deal of very pale-green, nearly-colourless, highly-refractive and
much-cracked augite (malacolite) occurs in short prisms, usually with
octagonal sections, and exhibiting a well-marked prismatic cleavage.
It is frequently twinned, and occasionally encloses felspar-prisms.
These minerals are embedded in a dull, greenish-brown, glassy
matrix, largely converted into yellow-and-green palagonite, which
in its turn has been replaced in part by zeolites. Small magnetite-
or ilmenite-granules are plentiful. The ilmenite, which is evidently
secondary, occurs in minute rhombs and hexagonal plates, with the
ordinary white leucoxene-products, some of the skeleton-crystals
showing very good examples of the characteristic mesh of white
rods. The altered glass has the same general character as that of
the palagonite-tuffs; it occurs in roundish patches, portions of
which are milk-white in incident light, and with weak chromatic
polarization, and sometimes exhibits a fibrous or spherulitic structure.
Minute green granules, milk-white in reflected light, are common
in these palagonite-areas, especially along their borders, representing
a further change in the alteration of the glass. It is possible that
some of the larger circular areas represent vesicles. The rock is an
augite-andesite with a hyalopilitic groundmass, in which much
of the residual glass is converted into palagonite, and a good deal
of secondary ilmenite occurs (Pl. XLIIT, fig. 5).

In some cases (516 a, 528) phenocrysts of felspar measuring up
to 0:05 inch, as a rule simply twinned, and often arranged in radial
groups, are embedded in a mesh of much smaller crystals; while in
(528) many elongated vesicles are seen, filled with a pale-green,
spherulitic, brightly-polarizing substance, often with a bordering
zone of colourless zeolite, which, between crossed nicols, shows
a fibro-radiate or minutely-spherulitic structure.

No. 525, just below the dolerite, is much darker in colour than
the typical andesite, very fine-grained, with pale-green flecks, and
in the hand-specimen it is almost impossible to distinguish it from
the fine-grained compact dolerite. Under the microscope, the
matrix is nearly black, and, with a high power, appears dusted all
over with very minute grains of secondary magnetite and ilmenite,
which appear not only in the matrix, but covering largely the
phenocrysts. Much pale augite is present, together with squarish
felspar-phenocrysts of low extinction-angles, as well as felspar-
microlites in the glassy matrix, and many vesicles filled with a
pale-green, faintly-polarizing substance (? delessite), often showing
zonary banding, and a fibrous or spherulitic structure. In spite of
the close microscopic resemblance of this rock to some of the finer
dolerites or basalts, there can be no doubt that it belongs to the
Andesite-Group.

At the top of the gulley, a little way down the north-eastern

DE 2

472 . PROF, W. S, BOULTON ON THE [ Nov. 1904,

slope, and just outside the wood (573, 513), are dark, fine-grained,
basic-looking rocks of much the same type as No. 525, which, in
my first examination of the hill, were mapped as intrusive basalt.
Microscopically the felspars are milky-white by reflected light, in
places blotched with hematite, while the matrix is of a pale
yellowish-green. Much secondary ilmenite with leucoxene; the
pale, much-cracked augite of the andesite-lava ; and a hyalopilitic
groundmass, with much of the glass converted into green palagonite,
are also seen. Circular vesicles are common, filled with concentric
zones of a green substance exhibiting well-marked spherulitic
structure, a colourless, brightly-polarizing substance, and calcite.
These rocks are associated with hard hilleflintas, as appears to be
the case generally. The close proximity of the newer basic group
probably accounts for the large quantity of secondary iron-ore
present, and the consequently more basic appearance of the rock.

The silica-percentage of No.516¢, a typical specimen of the augite-
andesite, is 50°67; while the specific gravity of five different specimens
from various points on the hill varied from 2°76 to 2°83, giving
an average of 2°80. The rock is thus practically basic ; but, from
the comparative abundance of felspar (probably oligoclase) and the
absence of olivine, it is perhaps more convenient to style it a
basic augite-andesite, or andesitic basalt.

(qd) Summary of the Andesite-Group.—aA marked feature
of the Andesite-Group just described is the preponderance of tufts,
generally glassy, but sometimes made up almost entirely of broken
crystals of oligoclase or andesine. These tuffs are the fragmenial
representatives of a basic augite-andesite lava, which in places is
interleaved with the tuffs. From the blade-like character of some
of these masses of andesite, and, in places, their tendency to an
ophitic structure, it would be unwise to ignore the possibility of
the intrusion of some of them into the tuffs. But the evidence,
both petrological and in the field, and especially the occurrence of
lapilli of similar andesite in the associated tuffs, seems to point
to their bedded origin ; and, in any case, there can be little doubt
that both tuffs and andesites belong to the same petrological series,
and are of the same general age.

The quantity of palagonitized glass in these tuffs and lavas is
remarkable, and equally so the comparative freshness of the
palagonite, considering the great antiquity of the rocks.

The substance, palagonite, is not uncommon in the older glassy
volcanic rocks of Britain and elsewhere, both in basic tuffs, and as
an alteration-product of the glassy residue of basic lavas. Thus
Prof. Cole has described and figured it in the andesite-tuff of Snead
near Bishop’s Castle, as well as in the associated andesite-lavas !;
and palagonite-tuffs in the Carboniferous rocks of the Forth Basin,

* “On some Additional Occurrences of Tachylyte’ Quart. Journ. Geol. Soc.
vol, xliv (1888) pp. 305-306 & pl. xi, fig. 5.

Vol. 60.] | IGNEOUS ROCKS OF PONTESFORD HILL. 473

and the Pebidian of St. David’s (Pembrokeshire), have been figured
and described by Sir Archibald Geikie'; while Prof. Zirkel has
described tuffs of this nature from Nevada and elsewhere.” But
the finest palagonite-tuffs are the more recent ones of Sicily,
Iceland, the Canary Islands, etc., including those of Palagonia with
the type-palagonite of Waltershausen, the characters of which
have been summarized by Prof. Penck.* Through the kindness of
Prof. Judd, 1 have been able to examine some of these rocks, as
well as specimens from Samoa, given to me by Mr. H. T. Waller.

In the palagonite-tuff from Galdar (Grand Canary), lapilli of
orange, reddish-brown, and yellow palagonite (average measurement
= 2 inch across), contain fresh clear olivine-phenocrysts ; circular
vesicles lined or filled with zeolites; and the same zeolite (phillipsite)
forms a fibro-radiate, mammillated border round the lapilli, the
outside margin of this border having a bright-yellow colour.*

In the Samoan rocks the palagonite is yellow, orange, or reddish-
brown, with a singular absence of separated iron-oxide, and enclosing
microlites of felspar, and phenocrysts of fresh, nearly colourless
olivine, together with round or elongated vesicles filled with
zeolites.

The tuff from Samoa contains lapilli, up to half an inch across,
of yellow and orange-yellow, faintly-polarizing palagonite, crowded
with minute and perfectly-round or much-elongated vesicles, and
containing fresh, nearly-colourless phenocrysts of olivine. The
vesicles are mostly filled with zeolites, a clear, colourless border of
a doubly-refracting substance, and a dark, nearly-opaque centre
of minute brown granules, possibly iron-oxide, the whole giving a
dusky cross in polarized light. Distinct from these vesicles, and
much smaller, minute gas-pores are visible, often tilled with pala-
gonite ; while others, with a faintly-marked radial and concentric
structure, are slightly affected by polarized light, and probably
represent globulites, or the variolitic structure on a small scale.
In one specimen from Samoa, each fragment of pale yellowish-brown
palagonite, crowded with microlites and skeleton-crystals of felspar,
is ringed round with a darker border of orange-yellow palagonite,
and the vesicles have a border of the same brown material, the
centres being filled with colourless zeolite. Except for the presence
of olivine in these rocks, and the somewhat fresher, clearer, and
almost isotropic character of this palagonite, there is scarcely a
detail of structure and appearance that cannot be matched in the
palagonite-tuffs of Pontesford.

In the volume on the Deep-Sea Deposits of the Challenger

1 Trans. Roy. Soc. Edin. vol. xxix (1880) pp. 513-16 ; and ‘ On the supposed
pre-Cambrian Rocks of St. David’s’ Quart. Journ. Geol. Soc. vol. xxxix (1883)
pp. 295-300.

* U.S. Geol. Explor. Fortieth Parallel, vol. vi ‘ Microscopical Petrography
(1876) pp. 272-75 & pl. xii, figs. 3-4.

3 * Ueber Palagonit- und: Basalttuffe ’ Zeitschr. d. Deutsch. Geol. Gesellsch.
vol. xxxi (1879) pp. 504-77.

* Compare Challenger Reports: ‘ Deep-Sea Deposits’ (1891) pl. xviii.
figs. 2 & 3.

474 PROF, W. 8. BOULTON ON THE [Nov. 1904,

Reports,’ Sir John Murray & the late Prof. Renard described
palagonite-, glassy-, and crystal-tuffs, dredged from the bottom of
the ocean, which again show characters almost identical with
those of the Pontesford rocks.

It seems probable that the conversion of the basic andesite-glass
into palagonite, in the case of the Pontesford rocks, took place
soon after their eruption, and that further and later changes in
the rocks have affected the crystalline constituents and fine matrix
of the tuffs, rather than this palagonitized glass. It has been con-
tended by Prof. Penck, Sir John Murray & the late Prof. Renard,”
and others, that the conversion of basic glass into palagonite is
brought about largely by the hydrochemical action of sea-water,
whereby changes take place which tend to the formation of zeolites.
That the tuffs of Pontesford were deposited in water is abundantly
clear, from the fine and regular lamination of some of the tuffs and
halleflintas, and the pronounced bedding of some of the voleanic
grits.

(4) Rhyolite-Breccias and Grits associated with the
South-Hastern Rhyolite.

It will be seen from the map (Pl. XX XVIII) accompanying this
paper that a strip of dolerite at the southern end of the hill inter-
rupts the succession of the bedded volcanic group. Andesite-tuffs
and lavas can be traced right up to this dolerite on the western
side, and the same rocks are met with along the footpath in the
adjacent field (535) cropping out through the dolerite, which makes
up nearly all the ground at this extreme southern end. On the
eastern side of the dolerite, along the footpath by the side of the
fence, which roughly corresponds to the little cross-fault marked on
the map, the andesite-rocks are again met with in smail and rather
obscure outcrops (536, 537). No. 536 is much brecciated, iron-
stained, and under the microscope shows a large amount of
secondary quartz (it yielded on analysis 84°70 per cent.). If the
longitudinal fault through the centre of the hill (see p. 453) runs as
far south, it would probably come through this point.

No. 537 is a pale, siliceous-looking rock, with a distinct banded
appearance, the bands running parallel to the general strike of the
andesite-group. Under the microscope it is found to be a crystal-
tuff, with broken crystals of felspar 0-01 to 0-07 inch long, showing
both simple and lamellar twinning, and set in a finely-banded,
dusty matrix, containing a few lapilli of decomposed vesicular
glass.

No. 17 L is a fresher-looking rock, but with much iron-staining,
and yellow and green secondary products. It is full of small
felspar-laths with a parallel arrangement, extinguishing parallel
(or nearly so) to their length, with a few larger crystals showing

1 Pp. 304-311 & pl. xviii.
? Ibid, p. 307.

‘

Vol.60.] . IGNEOUS ROCKS OF PONTESFORD HILL. 475

extinction-angles up to 15°. The structure is typically pilotaxitic,
though in places, where there is more residual glass, it might be
more exactly termed ‘ hyalopilitic.’

These rocks, which are evidently of the andesite-series, though
perhaps originally more acid than those in the same series farther
north, pass at once into typical acid tuffs or breccias,
which culminate in the South-Eastern Rhyolite.

A hard, flaggy, pink, felsitic-looking rock with green angular
chips (538, 540, 543, 545) is the first band of these markedly-acid
tuffs, with structures generally like those in the Westphalian
Devonian tuffs described by Miigge.*

No. 538 is a rather fine-grained variety, made up of very small
fragments of red, vesicular, altered glass with the typical ‘ Bogen-
struktur, set in a dirty-green matrix of fine glassy and crystal
dust. Larger crystals of felspar, showing both simple and lamellar
twinning, are present, together with rounded lapilli of vesicular
glass measuring up to 0°14 inch across; in one place the vesicles
have been drawn out into long and extremely-fine tubes. The
rock has the same general structural character as the palagonite-
tuffs, and was evidently formed under much the same conditions,
in this case by the breaking up of a perlitic and very vesicular
acid glass, the glass becoming afterwards strongly coloured with
iron-oxide. Its percentage of silica is 74°83, and the specific gravity
is 2°64.

No. 540 is in the same band as 538, but is coarser in texture,
with green chips measuring up to 0°3 inch in length. The matrix,
greenish in colour, is made up of fine glassy dust, embedded in
which are many minute red splinters of glass, with curved edges,
and often showing the optical phenomena of tension, like those
observed in Rupert’s drops; together with phenocrysts of orthoclase-
felspar (some 0-03 inch long), and irregularly-shaped lapilli of
green, fine-grained, banded tuff.

This glassy breccia is followed by a bright-red and green flagg
grit (839, 541), in places dipping north-westward into the hill
at about 80°. A specimen (539) isa very striking rock under the
microscope (Pl. XLIII, fig. 4). It is made up of lapilli measuring
about 0-02 inch across, mostly of green and brownish-red vesicular
glass, often showing what looks like perlitic structure, but may be
the vesicular structure previously described in the matrix of the
Northern Rhyolite (pp. 457, 458); others are fragments of dark-
brown, nearly black glass, crowded with felspar-microlites ; others
again of felspar-crystais, more or less broken, usually exhibiting
simple twinning, together with occasional rounded blebs of quartz
0-05 inch across. The rock bears a general structural resemblance
to the grit in the Andesite-Group at the top of the gulley (512),
but the fragments are more glassy and the rock as a whole more
acid. The bright-red colour of this rock is due to the large amount
of hematite that has developed in the glass.

* ¢ Untersuchungen iiber die Lenneporphyre in Westfalen & den angrenz-
enden Gebieten’ Neues Jahrb. Beilage-Band viii (1893) p. 642.

476 PROF, W. 8. BOULTON ON THE | Nov. 1904,

The red-and-green grit is followed by a breccia of the type
of that on the other side of it (538, etc.), but distinctly coarser,
with a pinkish matrix containing angular yellow and green
splinters measuring | inch or more across. Sometimes the rock
is bright bluish-green with pink glassy splinters, making up one of
the most striking rocks of Pontesford Hill.

These three bands (the red grit and glassy breccias above and
below it) can be followed along the south-eastern flank of the hill,
extending nearly up to the Camp, where they abut irregularly
against the basalt. In the glassy breccia (545) a vein of barytes
about a foot thick, running nearly east and west, has been partly
exposed.

(5) The South-Eastern Rhyolite.

The bedded rocks of the hill end southward in a rhyolite which
skirts it on the south-eastern side, and extends to the eastern
boundary-fault. It isa dark purple-red rhyolite, in some places
compact, but generally slaggy and coarsely vesicular and amyg-
daloidal, the vesicles measuring often 1 inch or more in length,
sometimes drawn out into fine tubes, and filled with yellow and
green secondary minerals.

Under the microscope, the vesicular, slaggy and banded structures
are very pronounced ; there is much staining with red iron-oxide, and
occasionally phenocrysts of felspar are present, generally showing
albite-lamellation. Much secondary quartz, yellow epidote, and
green chlorite, frequently in spherulitic aggregates, together with
radial growths of a colourless, brightly-polarizing, fibrous substance,
fill cracks and vesicles. Some of the larger irregular vesicles are
partly filled with highly-vesicular and spongy rhyolite, squeezed in
while the rock was still plastic ; while, in other cases, sharp, angular
portions of the felsitic matrix have been forced in by movement
more probably after partial or entire consolidation, as in the case of
the more angular fragments of fibrous felsitic matter in the quartz-
amygdaloids of the Northern Rhyolite.

In some specimens, the rock appears to consist of two magmas
that have imperfectly mixed, a darker and more ferruginous one
irregularly penetrating a paler variety; while, in other cases, the
bands vary considerably in colour, owing to the irregular distribu-
tion of the iron-oxide, so that the rock has a peculiar gnarled and
twisted appearance, suggestive of the knotty or grained structures
of wood. This gnarled structure is doubtless to be explained by
the partial separation of a more basic and ferruginous constituent
of the original rhyolite-magma before the extrusion of the lava.

In one place there is an included fragment, 0°05 inch across, of
nearly-black glass with clear vesicles. In a slice (1 Y 1) of one of
several of these rocks kindly lent to me by Mr. Parkinson, a well-
marked spherulitic structure is visible to the naked eye, the sphe-
rulitic bodies measuring 0°1 inch across. The rock was originally
the usual highly-vesicular and slaggy type of this South-Eastern

: Led
Vol. 60. | IGNEOUS ROCKS OF PONTESFORD HILL. ATT

Rhyolite, but a fibro-radiate structure, which is almost invisible
until the specimen is examined with crossed nicols, has developed :
in one place round an elongated vesicle, and in other places around
felspar-phenocrysts. A mosaic of secondary, colourless quartz,
possibly due to solfataric action, has largely replaced some of the
original brown glassy matter of these spherulites, but more espe-
cially the spaces between them, so that the spherulitic bodies appear
light-brown in a nearly-colourless matrix (Pl. XU, fig. 2).

The rock, as a whole, is more basic and slaggy-looking than the
Northern Rhyolite, contains little or no visible primary quartz, and
the felspars have more generally the albite-twinning. Its per-
centage of silica is 75°78, and its specific gravity 2°63.

(6) Summary of the Bedded Rocks.

TABLE SHOWING SrxicA-PERCENTAGES AND SPECIFIC GRAVITIES.

Percent.| Sp. Average |

Rock-specimens. of silica. | practi: sp. i |

pea orthernm Rhyolite (15) .2...25 i.e eee | 81-93 | 2°610 2°61

2. Andesite-Group. ae | a

(a) Red-and-green grits { (350) w"| Bro a570 f| 263

f (Age. Crag) .2...:-)...- | 53°45 2-743

(5) Palagonite-tuff4 (green, flaggy) .........) .... 2°837 | |
(coarse agg.-breccia)...| ...... 2700 $| 2°75

ep taeeen allen idita o.oo ce ccc. cecttaatess:| caoves 2-670 | |

le ASL PENT ca he) as a ee oe a 2-790 }

SR MOL a Pn Re 50°67 | 2°760)

f RO steer satierehsacsent | sehr ce | 2°800 |

(eyemdesite-tava 4) (57 @) site s2 elec dst | 2820+) 2:80 |

b ABS) ot opto. seate parreres: | 2-800 |

OE eee eee eee ha eee | 2-880 ) |

3. Rhyolite-grits and breccias ..................06- | 7483 | 2:640 2°64 |

| 4. South-Eastern Rhyolite.....................-.000-| 7578 | 2°630 | 2°63 |

The foregoing table shows that a considerable gap in silica-
percentage occurs between the Northern Rhyolite and the more acid
of the andesite-tuffs that immediately follow. This fact, combined
with the discordance in strike between the banding of the Northern
Rhyolite and the succeeding tuffs (see map, Pl. XX XVIII), might
be taken to imply, either that a considerable break in the volcanic
history here exists at the base of the tuffs, or that the junction is a
disturbed one. Unfortunately, the junction is largely obscured by
the dolerite, and where this is not the case, it is impossible to see
the relation of the two rock-groups. There still remains another
alternative, namely that the Northern Rhyolite is intrusive, as stated
by Mr. Blake,* and does not belong to the bedded volcanics of the

1 See ante, pp. 451, 452.

478 PROF. W. S. BOULTON ON THE [ Nov. 1904,

hill. While it may be impossible to disprove its intrusive origin
(for the banded and pyromeridal structures do not necessarily
negative its intrusion), it seems more in accordance with the
facts* to consider the rhyolite as an outpouring of lava, and to regard
its junction with the andesite-tuffs as a break in the history of the
volcanic activity represented by the Pontesford rocks.*

After leaving the Northern Rhyolite, the whole of the tuffs and
lavas, including the acid breccias and rhyolite at the south-eastern
end, form a continuous bedded series, despite the great difference
in the average silica-percentage of the Andesite-Group and the
Rhyolite-Breccias near the South-Eastern Rhyolite. Commencing
with a silica-percentage of nearly 60, these andesite-tuffs (together
with their associated lavas) become practically basic, with a little
over 50 per cent., and end with tuff and lava of a pronounced acid
type, with a percentage of about 75.

Thus, even if the Northern Rhyolite should be regarded as
intrusive (and to determine this finally, evidence from adjacent
Uriconian areas may have to be considered), the South-Eastern
Rhyolite must be regarded as bedded.

It is impossible to point definitely to the source of these bedded
volcanic rocks, but from the thinning of the tuffs towards the north-
east, and the diminution of the size of their lapilli, together with
their more gritty and washed appearance, when followed in this
direction, it might be inferred that they had their origin in some
vent or vents to the west of the present site of Pontesford Hill.

(7) The Intrusive Basic Rocks.

The basaltic rocks that make up the higher ground of the hill
vary considerably in colour and texture from point to point.
Typically, the rock is a dark or purplish-red, coarsely-amygdaloidal
dolerite or diabase, well shown along the eastern side, where it has
weathered into bare, bold cliffs. But in other places it is iron-
grey, very hard, fine-grained, and compact (60), or again somewhat
coarsely crystalline, and showing to the naked eye a marked
ophitic structure (35, 514, etc.). In places along the Camp at the
top of the hill, and elsewhere, the rock has an intense red colour,
due to the large amount of hematite contained in it. Specimens
may be collected showing a breccia-like appearance, the angular
fragments differing slightly in texture and colour from the sur-
rounding material, as if a partly-consolidated mass had been broken
up by subsequent intrusion. In other places the rock exhibits
a spheroidal structure (424), the spheroids measuring sometimes a
foot across.

* Tf the ‘inlier’ of rhyolite-rock (559), described on pp. 455-56, be a true
tuff, the evidence for the extrusive origin of the rhyolite would seem fairly
complete.

* For a description of an ancient, bedded, volcanic group, with sudden and
marked changes in chemical composition, see Sir Archibald Geikie’s ‘ Ancient
Volcanoes of Great Britain’ vol. i (1897) pp. 145 e¢ segg., and Quart. Journ.
Geol. Soc. vol. xxxix (1883) pp. 300 e¢ seqq.

Vol.60.] «IGNEOUS ROCKS OF PONTESFORD HILL. 479

The amygdaloidal type shows vesicles generally elongated in a
direction parallel to the strike of the bedded tuffs, sometimes 2
or more inches long, and filled with calcite and other secondary
minerals, which, however, have in some cases been dissolved out,
giving to the rock a very vesicular, slaggy appearance.

In a small quarry at the extreme south-western end of the hill
(431), very fine specimens of the amygdaloidal rock may be seen.
The vesicles, up to 2 inches across, which are here quite round,
have been filled with small spherulitic growths of red iron-oxide
and chalcedony with pronounced concentric rings, the clearer
siliceous portions showing a dark cross in polarized light. These
bodies generally line the wall of the vesicle, while the inter-
vening spaces have been filled mostly with calcite, but also
with chalcedony, chlorite, and, in some cases, further spherulitic
aggregates of iron-oxide. The rock is here much veined, showing
slickensides, and calcite has been deposited in large quantities.

Microscopic sections of the rock often show the felspars orien-

tated in the direction

Fig. 5.—Roughly-parallel wavy ridges on a of strike of the an-
weathered surface of basalt. (Natural desite-tuffs, and at
size.) one place in the
eee ee basalt of the Camp
(53), curious roughly-

en SCS parallel and wavy
I er lines, about one-
eighth of an inch

ee ee aaa apart, are visible on
the weathered sur-

face, and have the
same direction. They stand out as thin ribs, as if made of harder
material than the rest of the rock (fig. 5).°

Prof. Bonney has described a specimen from the Camp. He
says :—

‘The groundmass is full of elongated microliths of felspar with a slightly-
parallel grouping, generally plagioclase, but possibly in one or two cases ortho-
clase, with dark granules, probably in many cases hematite, and numerous
grains (generally rather irregular in outline) of augite. One of more definite
form is a compound erystal, about 0°02 inch in diameter. The rock is a basalt,
and more resembles that of a flow than of a dyke.’®

It may be added that the rock is a type of the finely-granular
dolerite or basalt, and that very little of the original material of
the felspars or augite remains, although the outlines of the crystals
are perfectly preserved. Silica-percentage = 47:62 ; specific gravity
= 2°84,

1 This is the opening referred to by Murchison: see p. 451.

2 A thin slice, taken across a selected specimen of the rock, did not reveal
any difference in structure or composition such as might account for these
curious ribs. The same structure, but on a larger scale, is to be seen in some
of the igneous rocks of Llanvawr, in the Ordovician of the Corndon district.

3 Quart. Journ. Geol. Soc. vol. xxxviii (1882) p. 124.

480 PROF. W. 8. BOULION ON THE [Nov. 1904,

A typical specimen of the granulitic dolerite (28) is from the
northern slope of the hill. It contains laths of felspar measuring
up to 0°05 inch in length, showing simple, but generally lamellar
twinning, and atendency to a parallel arrangement, with extinction-
angles as high as 40°, indicating a felspar of the basic labradorite-
series; plates of yellowish-brown augite measuring 0-04 inch across,
sometimes enclosing felspar-laths, and in one or two places sur-
rounding phenocrysts of olivine. Numerous large crystals of olivine,
0-06 inch long, showing the typical crystal-outlines and cracking,
are now converted into pale-green, faintly-polarizing serpentine,
with the characteristic heematite-rods and plates along the edges
and cracks. Frequently the phenocrysts are aggregated, so as to
approach the ‘ glomeroporphyritic’ structure of Prof. Judd. The
groundmass is made up of a fine mesh of felspar-laths having very
low extinction-angles, surrounded by much light-brown and greenish
augite in a finely-granular condition, and possibly some minute
olivine-crystals, together with grains of magnetite and ilmenite,
forming the pilotaxitiec structure of Rosenbusch.

The rock appears to be a typical example of a granulitic
augite-olivine-dolerite with two generations of felspar, the
earlier consisting of phenocrysts of labradorite, the later, forming the
matrix, a more acid feispar allied to oligoclase (Pl. XLIII, fig. 6).
For the full analysis and the specific gravity see p. 481.

No. 60, at the extreme southern end of the hill, may be taken as a
type of the ophitic dolerite. Itis made up of plates of yellowish-
brown, almost colourless augite nearly 0:1 inch across, enclosing laths
of labradorite measuring up to 0-08 inchin length. Olivine-pheno-
crysts are abundant, but are all converted into pale-green serpentine,
in some cases with a distinct spherulitic or fibrous structure, and
with the usual separation of magnetite and hematite along the
borders and cracks. The felspars have been largely replaced
by secondary substances, while the augite is relatively fresh ; but
this, too, in places has degenerated into a serpentine-product. Silica-
percentage=45°64 ; specific gravity = 2°84.

No. 569, from the edge of the dolerite-mass on the western
slope, shows pronounced ophitic structure, and the olivine, which is
plentiful, has completely degenerated ; much green serpentine, with
pale-yellow granules, white by reflected light, and plates and rods
of hematite and magnetite resulting from its decomposition.
Specific gravity =2°85.

No. 514, from the north-western slope, near the gritty tuffs of
the Andesite-Group, shows the ophitic structure to the naked eye,
with much green material, little laths of felspar, and occasional
round vesicles filled with a dark-green substance. Microscopic
examination reveals large plates of augite, of a deeper brown than
usual, enclosing felspar-laths measuring up to nearly 0-1 inch in
length. No recognizable olivine occurs, but much greenish-yellow
serpentine-material, often minutely spherulitic, and containing small
pale-brown granules, white by reflected light, as well as grains
iron-ore. A good deal of ilmenite with leucoxene occurs in this
rock. Specific gravity =2°86.

Vol. 60.] » IGNEOUS ROCKS OF PONTESFORD HILL. 481

The following table gives the percentage of silica and specific
gravity of varieties of the intrusive dolerite, taken from different
parts of the mass :—

No. of Percentage Specific

specimen. of silica. gravity.
Fs eee Be SE 48°30 2°88
GAN sak) as eee 3 45°64 2°84
rij eM Oe Tov a 47°62 2°84
BO Sagwdaed pacasnndant 45°81 2°84
EF gah gh 8 GBA cha el 50°15 2°83
<i fe esa ee 2°85
Te ee ee) Se eee na 2°86
nee oer ee gee 2°86
Average ......... 47°50 2°85

The following complete analysis of a compact, relatively-fresh-
looking sample of the granulitic dolerite (28) was kindly made for
me by Dr. C. F. Baker, to whom I am also indebted for the
determination of the silica-percentages in the foregoing table :—

E Il. III.
is Re PERE eae ee 48°30 49°860 48°8
2) Oia Se not est. 1:330 not est.
LT 1 ee eee 19-00 12°750 18-1
La |» ESO is 6-72 3°360 35
1 «| Epa ae Beak tee 397 11-380 72
SS ee: 8:93 8-710 8-4
|) ERS ee rere 3°03 4395 49
(ee ae aks 5°01 5°250 37
: i (eS RIE 2°38 0-570 ‘9
8 a als — 0-580 --
_) RRA Senso 2-05 (ignit.) 2°560 3°6 (ignit.)

Totals ...... 99°89 100-745 100°1
Specific gravity...... 2°88 2-907 2°79

I. Compact granulitic dolerite, Pontesford Hill.
Il, Dolerite, Rowley. (See J. J. H. Teall‘ Brit. Petrogr.’ 1888, p. 213.)
III. Dolerite, Hailstone Hill, Rowley. (Do.)

By the side of this analysis I have placed two analyses of the
dolerite, intrusive in the Coal-Measures of Rowley (Staffordshire),
with which the Pontesford rock seems to show some points of
resemblance. It will be noted, however, that the iron is mainly in
the ferric state in the case of the Pontesford dolerite, and the
minerals in the latter rock are not nearly so fresh, in general, as in
the Rowley rock. This is particularly the case with the olivine
and the felspars, while the augite has not the deep purplish-brown
colour that characterizes that mineral in most of the Rowley rocks.’
In this connection it should be borne in mind that the Rowley
specimens, especially those collected by Allport, were obtained from

1 Probably due to an absence of titanic acid in the Pontesford rock. Un-
fortunately, in the above analysis, titanic acid was not looked for.

482 PROF. W. S. BOULTON ON THE [Nov. 1904,

a relatively-fresh and unaltered portion of the rock, whereas, owing
to the absence of quarries or other deep openings, these from
Pontesford were taken from near the surface. The general resem-
blance in chemical composition, mineral contents, and structures of
the Pontesford rock and that of Rowley would apply also to the
dolerites of the Clee Hills, Kinlet, and the east of the Wrekin,
and applies almost equally well to some of the Tertiary dolerites
of Scotland, described by Prof. Judd.1. On the other hand, it
differs from most of the intrusive dolerites of North Wales, mainly
in the absence of olivine in these latter rocks; while the olivine-
diabase or basalt-lava, associated with the Pebidian rocks of
St. David’s (Pembrokeshire), described by Sir Archibald Geikie,*
differs from the Pontesford rock, mainly in the much greater amount
of magnesia and smaller quantity of potash in the Pembrokeshire
rock.

(8) Relation of the Intrusive Basic Rocks to the
Bedded Rocks.

Although the general trend of the dolerite-masses of the hill is
with the bedding of the tuffs, there can be no doubt that the
dolerite is intrusive in the latter, notwithstanding that some of the
characters, such as the coarsely-vesicular structure and the parallel
arrangement of vesicles and felspar-crystals, are those generally
associated with bedded lava-flows. In some places (516d, 201)
the dolerite can be seen penetrating, and enclosing masses of, the
andesite-tuffs and lava, while the irregular junction of the dolerite
and the bedded rocks (see map, Pl. XX XVIII) would preclude the
possibility of its being interbedded with the latter.

It is highly probable that the dolerite forced its way into the
underlying tuffs and lavas, mainly along two lines of weakness,
near the south-eastern margins of the two dolerite-masses shown on
the map, and, with relief of pressure, spread out among the bedded
rocks. But whether the dolerite actually came out at the surface,
or formed a laccolitic mass between the tuff-series and newer beds
now removed (possibly Cambrian or Bala, both of which are in the
immediate vicinity), there is no direct evidence to show. It would
seem more probable, however, that the dolerite invaded the bedded
rocks during the disturbance of the latter, which resulted im their
present high inclination (see map and sections, Pls. XX XVIII &
XXXIX).

LTV. GENERAL SUMMARY OF ConcLUSIONS.

The present paper is confined to a description of the characters
and sequence of the rocks within the limits of Pontesford Hill, and
no attempt is here made to correlate them with those of other
Uriconian areas.

1 Quart. Journ. Geol. Soe. voi. xlii (1886).
* Ibid. vol. xxxix (1883) p. 293,

GEOLOGICAL SKETCH-MAP
OF
PONTESFORD HILL, SHROPSHIRE
BY
W.S. Boulton.

Seale of Feet
190 290390400 “590

LG
ae i Re j
: Ns t;
— WN,

Note The different types in the Andesite.
that itis impossible to represent them
The Numbers (@568) mark the chief outcrops referred to in the.text

Explanation
———

Northern Rhyolite
Red & Green Grits (‘‘Felsitic’)
Andesite
Group

Halleflintas
Palagonite-Tuffs
Andesite-Lavas
Rhyolite-Breccia

Red & Green Rhyolite-Grit
South-Eastern Rhyolite

Intrusive Basalt & Dolerite

—~——— Contour-Lines ee ee ee eee, Fait

-Group are so confusedly interbedded,
diagrammatically on the Map.

Joop ‘umoryenh
: ok mn 5

pd

.

RAG yee

=

~~

a. Geol. Soc, Vol. LX, Pl. XXXIX.

RALIZED SECT

¥
S
=
ron
%
=
rx}
%
‘a

5.S.E.

ALONG LOWE

Felsitic-Looking’) Grit

reen Rhyolite-Grit. & Vertical Scale

300. 400 soofeet

Quart. Journ, Geol. Soc, Vol. LX, Pl. XXXIX.

GENERALIZED SECTION THROUGH PONTESFORD HILL FROM N.N.W. To S.S.E.

SECTION ALONG LOWER WESTERN AND SOUTHERN FLANK OF PONTESFORD HILL.

RAY

4

1, Northern Rhyolite. 2,Red and Green (‘FelsiticLooking’) Grits, 3.Red Andesite-Tuff. 4.Palagonite-Tuff, Red and Green Grits, Halleflintas and Andesite-Lava,

5.Pink Rhyolite-Breccia. 6,Red and Green Rhyolite-Grit. 7.South-Eastern Rhyolite. 8.Intrusive Basalt and Dolerite. Horizontallg: Vertical Scale

© 00 ap goo goo soofeet

Vol. 60. | _ IGNEOUS ROCKS OF PONTESFORD HILL, 483

Pontesford Hill is a ‘ plagioclinal ridge’, bounded on all sides by
faults, consisting entirely of igneous rocks, though some of the fine
tuffs and volcanic grits show unmistakable signs of deposition in
water.

Two distinct groups of igneous rocks are found :—

1. A Bedded Group, consisting of the Northern and South-
Eastern Rhyolite respectively, differing in composition and structural
characters. Of these, the Northern Rhyolite, of Uriconian type, is
probably bedded, but may be intrusive in the Andesite-Group, while
the South-Eastern Rhyolite, which is associated with breccias and
grits of the same composition, is certainly bedded. Between these
acid rocks intervenes a thick series of basic andesite-tuffs (palagonite,
halleflinta, crystal, and gritty), interbedded with basic augite-
andesite lava.

Leaving out of account the highly-siliceous Northern Rhyolite,
the bedded tuffs and lavas begin with a silica-percentage of about 56
and pass gradually into rocks, which form the bulk of the Andesite-
Group, with a little over 50 per cent.; these again become somewhat
more acid, and then pass up abruptly into true rhyolite-grits and
breccias and rhyolite-lava, with about 75 per cent. of silica.

The general strike of these bedded rocks is north-north-east and
south-south-west, parallel to that of the neighbouring Longmynd
rocks, with an average dip of about 80° east-south-eastward ; while,
at the extreme south-east of the hill, the rhyolite and associated
breccias dip in the opposite direction (west-north-westward) at
about the same angle.

2. Olivine-Augite Dolerites (granulitic, ophitic, or coarsely
amygdaloidal), having a chemical composition and mineralogical
characters similar to those of the dolerites of the Carboniferous
districts of Staffordshire and Shropshire, are intruded among the
bedded rocks in laccolite-like masses.

I have to express my gratitude to Prof. Lapworth for the en-
couragement and assistance which he has so readily accorded to me
during the progress of this work, and also to Prof. Sollas for his
kindness in allowing the micro-photographs for the plates to be
taken in the Geological Laboratory at the University Museum,
Oxford.

EXPLANATION OF PLATES XXXVIII-XLIII.

PuaTE XXXVIII.
Geological sketch-map of Pontesford Hill, on the scale of 400 feet to the inch.

PiuatE XXXIX.

- Generalized section through Pontesford Hill, from north-north-west to
south-south-east ; and section along the lower western and southern flank of
Pontesford Hill.

Fig.

Fig.

bo

Ts

bo

Ay

ho

iw)

Co

dS

~

6.

PROF. W. S. BOULTON ON THE [Nov. 1904,

Puate XL.

. Northern Rhyolite (15), showing part of a nodule with mushroom-

growths and fibrous matter traversing small spherulitic spaces. The
matrix exhibits a perlitic structure with ‘ micro-lithophyses. X 17.
(See pp. 457-58.)

. Northern Rhbyolite, showing part of the fibrous wall of a nodule

(in the upper part of the figure), enclosing felspar-phenocrysts, with
angular portions of the wail in the quartz-amygdaloid (to the right
of the figure). Bands of chalcedony and spherulitic felsitic matter
surround the fibrous wall and detached angular portions, the rest of
the amygdaloid consisting of quartz and brown spherulites. x 17.
(See pp. 459-60.)

Pirate XLI.

Northern Rhyolite, showing part of the double wall of a nodule, in
which felspar-phenocrysts and radiating tufted growths are visible.
The light space between the brown fibrous walls is filled with a quartz-
mosaic, enclosing small brown spherulites. x 17. (See p. 459.)

. South-Eastern Rhyolite. Definite spherulitic growths are seen, but the

radial structure is only faintly visible in polarized light. Secondary
quartz has largely replaced the substance in the spaces between the
spherulites. X17. (See p. 477.)

PuatEe XLII.

Andesitic gritty tuff (205), with lapilli of andesite-glass filled with
felspar-microlites, vesicles, etc. x 25. (See p. 467.)

. Palagonite-tuff (Agg. Crag, 6). At the top of the figure is a frag-

ment of palagonite of a bright orange-yellow colour, enclosing felspar-
microlites and vesicles with well-marked zonary banding. The dark
border round this glass-fragment is made up of a mass of small frag-
ments of the same palagonite. The rest of the field consists of small
fragments of palagonite, in a light-grey matrix of secondary zeolitic
matter. x 25. (See p. 467.)

. Palagonite-tuff (308), showing abundant, green, vesicular palagonite-

fragments, in which decomposed felspars are embedded ; zeolites fill the
vesicles, and make up the bulk of the groundmass. Xx 25. (See p. 469.)

. Coarsely-laminated halleflinta (574), showing finer bands of glassy dust

and coarser bands of yellowish-green palagonite-tuff. (x 25.)

Puatre XLITI.

. Palagonite-tuff (518), with characteristically-shaped glassy fragments

turned into green palagonite and filled with microlites of felspar and
round vesicles, showing zonary banding, and now filled with zeolites.
Cx 24.)

. The same, showing in the lower half of the figure a portion of a large

lapillus of very vesicular light-brown glass. (x 29.)

. Finely-laminated halleflinta, with grey (coarser) and yellow (finer)

bands of fine-grained glassy and erystal-dust. The glassy particles
are all converted into palagonite. x 25. (See pp. 467-68.)

. Red-and-green grit (539), associated with the South-Eastern Rhyolite,

showing cloudy felspars, rounded grains of quartz, and dark curvi-
linear splinters of altered glass, which are yellow, green, or red in
colour. X 233. (See pp. 458, 475.)

. Andesite-lava (516 ¢) showing a mesh of felspar-laths in a matrix which

is now largely converted into orange-yellow palagonite (the nearly-
black portions in the figure). In the centre is a group of pale-yellow
augite-crystals. x 24. (See p. 471.)

Granulitic olivine-dolerite (28). There is a cluster of labradorite- and
olivine-crystals, the latter converted into pale-green serpentine, with
heematite-rods and fibres along the cracks and borders. The matrix
consists of a ‘granulitic’ aggregate of felspar and augite. x 233.
(See p. 480.)

Quart. JourRN. GEOL. Soc. VoL. LX, PL. XL.

THE IGNEOUS ROCKS OF PONTESFORD HILL (SHROPSHIRE).

Photomicro, VW”. S. Boulton Bemrose, Colle.

Quart. JouRN. GEOL. Soc. Vor. LX, PL. XLI.

% 11.

Fig. 2.

THE IGNEOUS ROCKS OF PONTESFORD HILL (SHROPSHIRE)

Benrose, Collo.

Photomicro, W. S. Boulton.

QuarT. Journ. GEOL. Soc. Vor. LX, PL. XLII.

x O25:

Fig. 2.

x 25.

Fig. f.

x 95.

4.

Fic.

x 25.

Fic. 8.

THE IGNEOUS ROCKS oF PONTESFORD HILL (SHROPSHIRE).

a }

Bewroce.

Photomicro, W. S. Boulton,

, : ef | Quart. Journ. GEOL. Soc. VoL. LX, PL. XLII

THE IGNEOUS ROCKS OF PONTESFORD HILL (SHROPSHIRE).

Photomicro, W.S. Boulton. Bemrose, Colic.

Vol. 60. ] | IGNEOUS ROCKS OF PONTESFORD HILL. 485

Discussion.

The PresipENT said that he felt that the detailed petrographical
descriptions given by the Author were of much value. He stated
that hopes had been held out that Prof. Lapworth would come to
the Meeting, and he felt sure that all the Fellows present would
regret his absence and the cause of it. In these circumstances, he
asked the Secretary to read some remarks which Prof. Lapworth
had kindly contributed to the discussion.

Prof. Warts said that Prof. Lapworrn had hoped to attend the
Meeting, and to speak upon the stratigraphical aspect of the question,
but unfortunately he was not well enough to be present. He had,
however, asked him to say that

‘the tuffs and lavas of Pontesford were clearly faulted against Cambrian strata
on the western side of the hill, while Bala Beds were exposed at several points
in the valley running practically all along its eastern side. These Pontesford
rocks, however, were merely a portion of a broken band of Uriconian rocks
occurring at intervals from Plealey on the north to Linley on the south, and
following at once in contact with Upper Longmyndian strata near both ends
of this line, inverted in position, however (like the Longmynd generally), in
the northern half. Uriconian volcanic rocks also occurred on the eastern side
of the Longmynd, as at Ragleth, Caradoc, and elsewhere, where, however,
they rested transgressively upon the Lower Longmyndian and began with the
so-called Helmeth Grits.

‘The Longmyndian formation itself (which was made up of a Lower division
of grey, green, and red shales and grits, reminiscent of the Charnian of
Leicestershire; and an Upper division of red sandstones, grits, and conglo-
merates, reminiscent of the Torridonian of Scotland, with an intermediate
zone—the Bayston Group—combining characteristics of both) was certainly
sedimentary throughout. But the materialsof which the beds were made up
appeared to have been largely pyroclastic in origin, and were often suggestive
of simultaneous volcanic action at no great distance outside the Longmyndian
area. Broadly speaking, the amount of this ashy or felspathic material in-
creased as the succession was ascended, and the typical volcanic rocks of the
so-called Uriconian marked apparently the local incoming or culminating
phase of this volcanic action, connected perhaps with the movements which
brought the Longmyndian to a close and prepared the way for the Cambrian.

‘The igneous rocks of Pontesford Hill, both bedded and intrusive, although
perhaps not more varied, were less involved than those of the other Uriconian
areas ; and now that the Author had so admirably cleared up their character
and inter-relations, he hoped that he would carry on his researches into the
more complicated Uriconian areas in other parts of Shropshire.’

The Rev. J. F. Brake said that he had not been able to follow
the details so rapidly given by the Author, but he hoped to read
them more at leisure. Although he (the speaker) had referred to the
relations of Pontesford Hill, he had not attempted any complete
account of it, and he would only venture the remark that volcanic
tuffs and ashes appeared to him in many cases to be somewhat
too ireely quoted, considering the difference that they showed when
compared with those exposed among recent volcanoes.

Mr. Parkinson, referring to the great difficulty, from a petro-
graphical point of view, of the Pontesford rhyolites, said that he
felt that all students of this group of rocks would be grateful to the
Author for the able paper which he had submitted to the Society.

Q.J.G.8. No. 240. 2.

4386 THE IGNEOUS ROCKS OF PONTESFORD HILL. _[ Nov. 1904.

The Author had mentioned that the spherulitic type of devi-
trification was not all of the same age, and the speaker asked
whether this, in part, might be connected with intrusion, as in the
well-known instance described by Prof. Bonney. The possibility
that these lithophysal rhyolites might be intrusive was a point of
considerable interest.

Prof. Groom drew attention tothe apparent resemblance between
the rocks described by the Author and these occurring as pebbles
in the Cambrian and Silurian Series of the Malvern Hills.

The AvrHor, in reply, said that he was not aware that the
spherulitic structure in the South-Hastern Rhyolite was due to
the intrusion of the dolerite. He agreed with Mr. Parkinson
that the presence of spherulitic and pyromeridal structures in the
Northern Rhyolite would be additionally interesting, if the latter
turned out to be intrusive; but the weight of evidence was in
favour of its bedded origin. Some years ago the Author collected,
and had sliced, a large number of specimens from the ‘ Warren-
House’ rocks, on the eastern flank of the Malverns, and he could
endorse what Prof. Groom had said with regard to the points
in common between them and some of the Pontesford rocks. He
thanked the Fellows present for their reception of his paper.

GENERAL INDEX

TO

THE QUARTERLY JOURNAL

AND

PROCEEDINGS OF THE GEOLOGICAL SOCIETY.

Aber-Dinlle Fault (& Caernarvon
earthquake), 241-42.

Aberdeenshire Area, Moine Gneisses
in, 412-14 ; evidence as to the High-
land sequence in, 423-29, 435-39.

Aberfoil (Perth), sect. to Allt
a’choinn, 15.

Aberfoil Slates, 13, 16-17 ; limestones
among, 28, 29.

Actanp, H. D., on a new Cave on the
Hi. side of Gibraltar, 30-35 figs. &
pl. vi (plan & sects.).

Acrodus minimus, 209.

After-shocks of Derby earthquake of
March 1903, 229-31 ; of Caernarvon
earthquake of June 1903, 239-40
& map.

Agglomerates of Spring Cove, 159 e¢
seqq., 164 figs.

Agglomerate-Crag (Pontesford Hill),
petrography of, 466-70 fig., pls. xlii-
xliii, & chem. anal.

Agnano (Italy), volcano of, 310.

Albite-gneisses of Loch-Lomond dis-
trict, 19-21 fig. & pls. iv—-v ; nature
of metamorphism of same, 26-27 ;
chem. anal. of, 23-24.

Allt a’choinn (Scotland), sect. to Aber-
foil, 13.

Alluvion ancienne, restriction of term,
316.

Almandine- garnets in Borrowdale
Volcanic Series, 101-102.

Alps, age of lake-basins between the
Jura & the, 65-69, 316-18.

Ammonites, Upper Jurassic, in Oxford
University Museum, &c., 54-64 figs.
& pls. ix—xii.

Amphiboles in Llyn-Padarn dyke-
rocks, 384-85; see also Horn-
blende.

Ampthill Clay, Perisphinctes vario-
costatus from, 59.

Amygdaloidal basalt at Middle Hope,
&e.. 140, 142-48 figs., 146, 152; at
Spring Cove, 152-53 & pl. xvii
(microscop. sect.), 158 e¢ seggq. figs. ;
a. b. of Pontesford Hill, 479.

Analyses, chemical, of Loch-Lomond
rocks, 22-24; of Pontesford- Hill
rocks, &e., 456, 469.

Andalusite in rocks of Moine Series,
427, 428.

Andesites of Dardanelles area, 253 e¢
seqg., 276-77.

Andesite- Group of Falcon Crag,
garnetiferous rocks in, 86-89 &
pl. xiii; A.-G. of Pontesford Hill,
454, 463-74 figs., pls. xlii-xlin, &
chem. anal.

Angle-Tarn Gill (Lake District), dykes
of, 74, 76.

‘Annealing’ of flints, 114.

Annual General Meeting, ix.

Anomia sp. (Rheetic), 201 & pl. xviii.

Anthracotherium cf. minus, 286 &
pl. xxiv.

Anticlines in the Loch-Lomond dis-
trict, 13-14; in N.W. Gloucester-
shire & Worcestershire, 355 ef
seqq.

Apatite in Llyn-Padarn dyke-rocks,
379; in rocks of Moine Series, 407,
408.

Aquitanian foss. fr. Dardanelles area,
285, 288 ; see also Oligocene.

age

488

Arabli (Turkey), Sarmatic freshwater
fossils from, 283.

Ardlui (Loch Lomond), metamorph-
osed albite-gneiss of, 26 & pl. v.

Arley-Mine coal-seam, 394.

Armboth Dyke, garnets in the, 86 &
pl. xiii.

Arnoup-Bemrossz, H. H., 216, 221,
227; on some Quartzite-Dykes in
Mountain-Limestone near Snelston
(Derbyshire), 364-69 & pls. xxx-
XXXi. ;

Artaki Peninsula (Marmora), 244.

Ascension I., specims., &c. from, ex.

Ashburton (Devon), map of the neigh-
bourhood of, 329.

Ashes above ‘ streaky’ rocks in Borrow-
dale Vole. Series, 97-98 & pl. xiv;
banded ashes in Haweswater dis-
trict, 99; do. at Great Crag, 92
fig.; ashes assoc. w. Carb. Limest.
of Bristol district, 140 e¢ segq.,
154-55 & pl. xvii; see also Tuffs.

Assets, statement of, xl.

Astroni (Italy), volcano of, 510-11.

Arkin, A. J. R., the Genesis of the
Gold- Deposits of Barkerville
(British Columbia) and the Vicinity,
389-92.

Auditors elected, v.

Augite-andesite of Pontesford Hill,
471 & pl. xiii, 472.

Augite-porphyrite, rock intermediate
betw. granophyre and, 78.

Auriferous deposits of Barkerville
(B.C.) & vicinity, 389-93.

Aust (Gloucest.), Rheetic at, 178-79.

Austria-Hungary, Geol. Surv. maps
presented, 11.

Avene, W. T., obituary of, Ixvi-
lxyili.

Avernus, Mt. (Italy), 309, 312-15.

Avicula contorta, 200, 202-203 ; zone
of, 189; see also Black Shales.

fallax, 203.

Axinus cloacinus, see
Hwaldi.

Awards of medals & funds,

xlviii.

Schizodus

<o—

Baker, ©. F. [chem. anal. of Pontes-
ford Hill rocks], 469, 481.

Bala age of most of the Llyn-Padarn
dykes, 373, 387.

Balance-sheet for 1903, xxxvi-xxxvii.

Bautpwin, W. (&-W. H. Surcuirrs),
Eoscorpius sparthensis, sp. nov.,
from the Middle Coal-Measures of
Lancashire, 394-99 figs.

Balloch Farm (Invercauld), quartzite,
&e. near, 414, 437-38.

GENERAL INDEX,

[Nov. 1904,

Balmoral (Aberdeen), Moine Series
near, 4388.

Balouk-keui (Turkey), Miocene, &c.
at, 245.

Banvie Burn (Perth), Moine Gneisses,
&e. of, 420-21, 432.

Barkerville (B.C.), genesis of gold-
deposits of, 389-93.

Barwiow-J AMEsSoN Fund, awards from,
XXMiil.

Barnwell (Cambs), Upper Gault lime
stone of, 860-63.

Barrow, G. [exhibits striated boulder
fr. Scilly Is.], evi; on the Moine
Gneisses of the East-Central High-
lands and their Position in the
Highland Sequence, 400-44 figs. &
pls. xxxili-xxxvii (map & microscop.
sects.).

Baryto-celestine at Redland, 175; at
Cotham Road, 178.

Basalts assoc. w. Carb. Limest. of
Bristol district, 137 et segg. figs.
& pls. xvi—xvii, 158-69 figs. ; basalts
of Pontesford Hill, 454, 478-82 fig.,
pl. xliii, & chem. anal.

‘Bastard limestone,’ 365.

Batuer, F. A., 34, 399.

Beaches, raised, sce Raised beaches.

Berapnewu, H. J. L., Barlow-Jameson-
Fund award to, xlviii.

Beaver, as a factor in alteration of
river-landscapes, 121.

Beinn-Ledi Group, 13 et segg., 17-
21.

Bruinrante, L. L., translates G. de
Lorenzo’s paper, 296.

Belinurus bellulus, assoc. w. Hoscorpius,
394, 398.

Beit, A. M. {on flint-implemts. fr.
Surrey], v; Implementiferous Sec-
tions at Wolvercote (Oxfordshire),
120-30 figs.

Bett, M., obituary of, lxxviii.

Bending, zonal, in the region of the
Alps, 66.

Bettws-Garmon & Clynnog Fault,
241.

Bibliography of the Edestide, 7-8;
of the glacial geology of Tasmania
38 et segg.; of igneous rocks assoc.
w. Carb. Limest. of Bristol district,
137 e¢ seqqg.; of the Rhetic Series,
190-92, 201, 212-15; of geology of
the district surrounding the Dar-
danelles, 274-75; of Pontesford
Hill, 450-52.

Bidston (Cheshire), Derby earthquake
recorded at, 222-23; Caernarvon
earthquake recorded at, 235, 237,

Biassy medallists, list of, xxxiil,

Vol. 60.]

Bitpt, Baron C. de, receives Lyell
medal for A. G. Nathorst, xliv.
Biotite in Llyn-Padarn dyke-rocks,

385; of the Moine Gneisses, &c.,
407, 412, 414 et seqq., 487.
Biotite-andesites of Dardanelles area,
253 et segg., 276-77.
Biotite-granulite of the Falar area,
434

Birmingham (Warwick), Derby earth-
quake recorded at, 220 fig., 221-22;
Caernarvon earthquake recorded at
235-37 fig.

Birnbeck Cove, see Spring Cove.

Black Shales (Rhetic) at Redland,
171 ef segg.; at Cotham Road, 177,
178; at Aust, 179 ; at Stoke Gifford,
195 ; condits. of deposit. of, 182-83 ;
nr. Chipping Sodbury, 195 ez segq.
figs., 215; in N.W. Gloucestershire
& Worcestershire, 349 ez seq.

Blair Atholl (Perth), Moine Gneisses
of, 409.

Buake, Rev. J. F., exhibits Amm.
variocostatus fr. Osmington, ii.

‘Blea Crag (Langstrath), intrusive
complex of, 70-76 fig. & pl. xiii
w. chem. anal.

Blotch-Rock of Moine Series, 409 e¢

seqq.

Bone Bed (Rhetic) at Redland, 172-
73, 174; at Aust, 179; B.-B. de-
fined, 179-80; condits. of deposit.
of same, 180-82; absent at Stoke
Gifford, 195; present nr. Chipping
Sodbury, 197; position of B.-B.,
210-12, 214; B.-B. & equivalents
in N.W. Gloucestershire & Wor-
cestershire, 349 ef segg.

. Bonney, T. G., ev.

Borrowdale Volcanic Series, garnet-
bearing & associated rocks of the,
70-105 figs. & pls. xiii-xiv (micro-
scop. sects. ).

Bosphorus, Devonian of the, 244;
format. of channel of, 261- 63 &
fig. (sects.).

Boulder, striated, fr. Scilly Is., evi,
118; do. fr. Gormanston Moraine
(Tasm.), 44 fig., 45.

Boulder-Bed of the Highland area,
448.

Boulder-Clays, typical, in Tasmania,
45, 51, 52.

Bourton, W.S., on the Igneous Rocks
at Spring Cove, ur. Weston-super-
Mare, 158-68 figs.; the Igneous
Rocks of Pontesford Hill (Shrop-
shire), 450-84 figs. & pls. xxxviii—
xliii (map, sects., & microscop.
sects.).

GENERAL INDEX.

489

Bourne Bank (Worcest.), Rhetic, &e.
at, 351.

Bow Fell (Lake District), intrusions
in the neighbourhood of, 76-79.

Braemar (Aberdeen), Moine Gueisses
of area flanking the Dee above,
412-13; evidence as to Highland
sequence in the area, 423 e¢ segg. &
pl. xxxvil.

Braaeg, G. S., 228.

Brassington (Derby) ), pipes in limest.
near, 370-71.

Breccia in new cave at Gibraltar, 30 e¢
segqg., 836; of Ore Gap, 77, 97 : gar-
netiferous, of Frith Wood, 87, 88;
of Glaramara, &c., 97-98; rhyolitic,
of Pontesford, 454, 474-76 & pl.
xlili.

Bristol District, igneous rocks assoc.
w. Carb. Limest. in, 137-57 figs. &
pls. xvi—xvii, 158-69 figs. ; Kheetic
sects. in, deser ibed, 170-79.

British Association geol. photographs,
evili.

British Coal-Measures, oceurr. of Edes-

tws in, 1-9 figs. & pl. i; see also
Coal-Measures.

Brooke, J. W., cx.

Brown, J.A., obituary of, Ixxv—Ixxvi.

Buckling structure in rocks of East
Central Highlands, 445.

Bull Crags (Langstrath), (E32

Burrows, H. W., 294.

Burtness Combe (Buttermere), intru-
sive complex of, 83-85.

Buscoe Sike (Bow Fell), porphyrite
of, 77.

Bushley (Worcest.), Rhztic, &. near,
301

Buttermere (Lake District), intrusive
complex of Burtness Combe, 83-
85.

Bye-laws, alterations in, vi—vil,
ev-CVl.

Viii,

Cadbury Camp (Somerset), igneous
rocks near, 147, 151.

Caernarvon earthquake of June 19th,
1903, & its aecessory shocks, 233-
42 figs. & pl. xx (map).

Cairngorm Granite, Moine Gneisses
of area south-east of the, 413-
14.

Calc-flintas of the East-Central High-
lands, 426-27, 428 et segq.

Calcite as a matrix of gold, 391, 392,
393.

Callater, Glen (Aberdeen), ‘ felspar-
rock’ of, 442-48.

Catverr, F., quoted, 255 et segg. 265
270, 272.

49()
Camaldoli (Italy), yellow tuff-volcano,
306.

Campana (Italy), volcano, 311.

Campyloprion, 3, 7.

Capodimonte (Italy), yellow tuff-vol-
cano, 306.

Caprara (Italy), trachyandesite of 510.

Carbonicola acuta, horizon of, 394.

Carboniferous glacial beds in Tas-
mania, 43, 49 & map (p. 50), 52.

Carboniferous Limestone, igneous
rocks assoc. with, in Bristol dis-
trict, 1387-57 figs. & pls. xvi-xvii,
158-69 figs.; sequence of C. L.
Series, 148; see also Mountain-
Limestone.

Cardinia concinna aff. regularis, 204—
205 w. fig. & pl. xviii.

Cardium cloacinum, 201, 207-208 fig.

—— protractum, 282-83 & pl. xxiv.

rheticum, 201, 208.

Cariboo Schists, 389.

Catalogue of Library, x, xiv.

Cave, new, at Monkey’s Quarry (Gib-
raltar), 30-36 figs. & pl. vi (plan &
sects.) ; see also Gough’s Cavern.

Cave-earth in Gough’s Cavern, 338-
39.

Celestine-bed at Redland, 175.

Central Highland Quartzite, 415 e¢
seqq.

Centrobatidee, families included in,
138.

Ceratodus latissimus, 209.

Chagford basin (Devon), so-called,
319,

Chalk (Lr.), Ptychodus decurrens from,
133-36 fig. & pl. xv.

Chalk-flints in Gunwalloe shingle-
beach, & in other Cornish localities,
118 e¢ seqgq.

Changes of level, continental, Ixxx—civ ;
in Dardanelles area, 261 e¢ segqq.,
272-73 & table i; in Neapolitan
area, 297-98.

Chaxhill (Gloucest.), Rheetic, &c. at,
OOO.

Cheddar (Somerset), human remains
found in Gough’s Cavern, 335-48
figs. & pl. xxix.

Chipping Sodbury (Gloucest.), Rheetic,
&e. near, 195-98 figs.; sandstone-
dykes at, 370.

Chlorite in Llyn-Padarn dyke-rocks,
385 & pl. xxxii.

Cigliano (Italy), voleano of, 311.

Cladocora ef. articulata, 290.

Crark, W. B., elected For. Corresp.,
cx.

Clay-beds, barren (Rhetic), 171 e¢
seqg., 184-85.

GENERAL INDEX.

[Nov. 1904,

Cuincu, G. [on flint-implements fr.
Surrey], v; exhibits palzoliths fr.
Marlborough, ex.

Cuosz, M. H., obituary of, Ixxi-
Ixxiv.

Clune (Perth), crag of Moine Gneisses,
405 fig.

Clunie, Glen (Aberdeen), geol. map of,
422; note on same, 428.

Coal-basin, Oligoc., of Keshan, 246-
47; of Tchatal Tepé, &c., 249.

Coal-Measures of Britain, occurr. of
Edestus in, 1-9 figs. & pl. i; C.-M.
(Middle), of Lancashire, Hoscorpius
from, 394-99 figs.; C.-M. round
Pontesford Hill, 453.

Cockshead Lane, see Snelston.

Colour-banding in gneisses coincident
w. bedding, 403.

Combos (Turkey), Oligoc., &e. at, 251,
252 fig.

Como, Lake of, origin discussed, 67.

‘Concertina-structure ’ in the Moine
Series, 443.

Concretion fr. Vancouver I., u.

Conglomeratic vole. rocks of the
Phlegrean Fields, 302-303.

Constructive metamorphism, 12-13.

Contact-metamorphism in the Loch-
Lomond district, 25-26.

Contemporaneous origin of igneous
rocks assoc. w. Carb. Limest. of
Bristol district, 1589-47 figs.

Continental elevation & subsidence,
lxxx-civ.

Coomb Hill (Gloucest.), Rhetic at,
Bol.

‘Coombe-Rock,’ possibly equiv. to
‘head’ of Cornish coast, 110.

Corallian (Upper) age of Perisphinctes
plicatilis, 56.

Corbicula semistriata, 287 & pl. xxiv.

Corbula sp. (Stampian), 227-88.

CorrrELp, W. H., obituary of, Ixxiv-
Ixxv.

Cornwall, probable Hocene outlier off
coast of, 113-19 figs.

Corrosion of flint-pebbles, 114, 118-19.

Cotham Marble at Redland, 171 ef
segg.; at Stoke Gifford, 175, 176,
195; at Cotham Road, 177, 178;
at Aust, 178; nr. Chipping Sod-
bury, 197; origin, &e. of, 185.

Cotham Road (Bristol), Rhetic at,
177-78.

Council, report of, ix; Council &
Officers elected, xxili-xxiv.

Craignahuillie (Scotland),
morph. grit from, 16 & pl. i.

Craters, concentric & excentric, 308
et segg.; do. of explosion, 309.

meta-

Vol. 60. ]

Creep along faults & earthquake-
phenomena, 242.
Cretaceous pebbles

shingle-beach, 113.
Crick, W. D., obituary of, xxx.
Crisci (Italy), Hill of the, 312.
Criscliffe Knotts (Lake District), dykes

below, 79, 82.
pat (Woreest.), Rheetic, &e. at,

in Gunwalloe

Croydon (Surrey), palzolith from, v.

Crush-brecciation, zone of, in Borrow-
dale Vole. Series, 97.

Crush-zone in Llyn-Padarn area,
378-79.

Crust-movements & changes of level,

civ.

‘ Crystal-tuffs’ of Pontesford Hill, see
Tuffs.

Crystallization, decreasing, belt of (in
Kast-Central Highlands), 415 ef
seqq.

CunntncHam-Craic, E. H., Metamor-
phism in the Loch-Lomond Dis-
District, 10-28 figs. & pls. ii-v.
(microscop. sects.).

Cycloseris ef. Perezi, 290 & pl. xxiv.

Dalnacardoch (Perthshire), pink-
edged gneiss of, 408 & pls. xxxiv,
XXXVi; Massive grey gneiss near,
409.

Dantet-Pincron Fund, awards from,
XXX, CIX.

Dardanelles (Turkey), Eocene & later
formations surrounding the, 243-75
figs. & pls. xxi-xxiii (maps); rock-
specims. & foss. fr. do., 276-95 &
pls. xxiv—xxv.

Dark Schist of East-Central High-
lands, 417 ef segg., 425-26 ; signifi-
cance of patches of same, 429-31.

Davizs, H. N., the Discovery of
Human Remains under the Stalag-
mite-Floor of Gough’s Cavern,
Cheddar, 335-47 figs. & pl. xxix.

Davison, C., the Derby Earth yuakes
of March 24th & May 3rd, 1903,
215-32 figs. & pl. xix (map); the
Caernarvon Earthquake of June
19th, 1903, & its Accessory Shocks,
233-42 figs. & pl. xx (map).

‘ Deep-sea’ deposit at Kilacheri, viii.

Defford (Worcest.), Rhetic, &c. near,
dol.

Denny Hill (Gloucest.), Rhetic, Kc.
at, 353.

Derby earthquakes of 1905, 215-32
figs. & pl. xix (map).

Destructive metamorphism, 11.

GENBRAL INDEX.

491

Devitrification-phenomena in Pontes-
ford-Hill rocks, 457 e¢ seqq.

Devonian rocks of the Bosphorus, &c.
244.

Diabase nr. Criscliffe Knotts, 79; of
Stony Tarn, 81; of Burtness Combe,
83-84.

Didacna crassa, 280 & pl. xxiv.

Diplomystus marmorensis, sp. NOv.,
284-85 & pl. xxiv.

Dixon, H. N., 124.

Dock Tarn (Lake District), garnet-
iferous andesite &e. of, 85, 88, 91,
92 fig.

Dolomitized limestone nr. Snelston,
364-65, 366.

Dome-like masses in Gough’s Cavern,
338 fig.

Donors to Library & Museum, lists of,
XiV-Xx.

Double shock in Derby earthquake,
218-21; relat. of sound to same,
225-26 ; double shock in Caernarvon
earthquake, 235.

Drainage-area of the Teign, map of,
320.

Dreissensia polymorpha, 280 & pl.
XXly.

rimestiensis, 281 & pl. xxiv.

Tschaude, 280 & pl. xxiv.

Drift-deposits at Wolvercote, &c.,
125-30; view of same at Peartree
Hill, 128; see also Boulder-Clay.

Driftwood, fossil, at Redland, 175.

Drygatsxt, E. D. von, elected For.
Corresp., cvili.

Dunhampstead (Worcest.), Rheetic at,
352.

Dunsford (Devon), map of neighbour-
hood, 527.

Dykes of sedimentary material in
limest., &e., 364 e¢ segg., 367, 369-
71; dykes of Llyn Padarn, age of,
372-88 & pl. xxxii (microscop.
sects. ).

Dynamic metamorphism, use of term,
378; d. m. in the Loch-Lomond
district, 11-12.

Eagle Crag (Langstrath), felspar-
garnet rock of, 94.

Earth-movements in the South of
England, 524, 332, 534; in N.W.
Gloucestershire & Worcestershire,
305 et segg.; of post-Bala age, in
Llyn-Padarn district, 372, 374-75,
388 ; see also Crust-movements.

Earthquakes, in Derbyshire in March
& May 1903, 215-52 figs. & pl. xix
(map); at Caernarvon, &c., in June

492

1903, 233-42 figs. & pl. xx (map) ;
earthquakes indicating falling-in of
Marmora sea-bed, 263.

Edestus, occurr. of, in Coal-Measures
of Britain, 1-9 figs. & pl. i.

Heinrichsii, 2, 6.

minor, 2 et segg. & fig.

triserratus, sp. nov., 4-8 fig. &
pli 1.

Egypt, Geol. Surv. maps presented,
iil.

Election of Auditors, v; of Council &
Officers, xxiv; of Fellows, i, ii, iii,
iv, Vil, CV, Cvli, Cix, cx, cxii; of For.
Corresp., evil, cxi; of For. Membs.,
iV, CVlil, cx.

Electrotypes of medals, xiii.

Hlevation (& subsidence), continental,
lxxx-clv.

Ehias, Mt. (Turkey), Hoc. foraminifera
from, 289.

Espun, J. V., on the Age of the
Llyn-Padarn Dykes, 372-88 w. map
& pl. xxxii (microscop. sects.).

Elvan, hearths of, at Prah Sands, 108,
109, 111-12.

Emergence (& submergence) of land,
lxxxili-civ.

Eneuisu, T., Eocene & later Forma-
tions surrounding the Dardanelles,
243-75 & pls. xxi-xxili (maps).

Enrichment, secondary, of metalli-
ferous deposits, 8390-91, 393.

Eobuthus rakovnicensis, contrasted w.
Eoscorpius sparthensis, 897-98.

Kocene (?) outlier off coast of Cornwall,
113-19 figs.; Eocene surrounding
the Dardanelles, 244-55 figs. &
pls. xXxi-xxlli (maps); Eocene
history of Devon, &c., 823-25.

Koliths (?) fr. Surrey, v.

Eoscorpius sparthensis, sp. nov., 894-
99 figs.

Epicentres of Derby earthquakes, 221,
230; of Caernarvon do., 234,
240.

Epidosite of Blea-Crag complex, 75-
76.

Epidote in Llyn-Padarn dyke-rocks,
381, 386 & pl. xxxii; in rocks of
Moine Series, 408, 410 et segg. &

lL. xxxy,

Eregli (Turkey), Miocene of, 255-56 ;
shells fr. same, 285.

Erratics, see Boulders, Glaciation, &c.

Eruptions in the Phlegrzan Fields,
300-13.

Eruptivity, shifting of axis of (in
Phlegrzan area), 509-10, 314.

Eskdale Granite, basic offshoots from
the, 79-83.

GENERAL INDEX.

[Nov. 1904,

Estheria minuta var. Brodieana, zone
of, 189.

Hstimates for 1904, xxxiv—xxxy.

Erueripe8, Mrs., resolut. of sympathy
with, vi.

Erueripes, R., obituary of, lxviii-lxxi.

Ethie (Cromarty), sandstone-cykes at,
369, 370.

Evans, Sir Joun, presents portrait of
himself, i.

Exhibits at meetings, regulations as
405 (OXI:

Exvron, H., obituary of, lxxviii-Ixxx.

Eycott Lavas, altered, 83; general
absence of garnets in, 89; E. L.
nr. Lingmell, 97.

Falar area (Glen Tilt), evidence as to
Highland sequence in, 433-35.

Faleon Crag (Lake District), garneti-
ferous rocks in andesite-group of,
86-89 & pl. xiii.

Fatconer, J. D., 15.

Fans of deposition illustrating format.
of Moine Gneisses, 440 ez seggq. figs.

Faults in Pontesford Hull, 453.

Fault-slips originating Derby earth-
quakes, 231-32; do. originating
Caernarvon earthquake, 241.

Faulted slate, fr. Ulpha, v.

Ferarnsipes, W. G., 238; on the Oc-
currence of a Limestone w. Upper
Gault Fossils at Barnwell near
Cambridge, 360-63.

Fellows elected, 1, ii, ili, iv, vil, ev,
cyli, ClX, CX, CXill; names read out,
exi, exli ; number of, ix—x, xxi.

Felsite, banded, of Burtness Combe,
84.

Felspar, significance of its associat. w.
garnet, 94-95; felspars in Llyn-
Padarn dyke-rocks, 380-82.

Films of mica in Moine Gneisses, 403,
407, 411 et segg., 434.

Fimbria subpectunculus, 289-90.

Financial Report, xxxiy—xl.

Firnate, Glen (Perth), Moine Series
in, 440 & pl. xxxvii.

Fuert, J. 8., Notes on the Collection
of Rock-Specimens made by Col.
English in European Turkey &
Asia Minor, 276-77.

Flexuring as primary cause of lake-
basins, 316 e¢ segg.; flexuring in
the South of England, 330, 332-33;
in N.W. Gloucestershire & Worces-
tershire, 355 et segq.

Flint, ‘ palzofractured,’ fr. the Mall,
ii; flint, veget. remains in, vi;
flint-flakes found in Gough’s Cavern,
345, 345 figs. ; flint-pebbles, corrosion

Vol. 60. ]

of, 114, 118-19; see also Paleoliths,
&e.

Fluxion-tuff, see Agglomerates.

Folding in Loch-Lomond district,
13-15; Lr. Tertiary, in Dardanelles
area, 250-252, 272 & pls. xxi—xxii
(maps); in Neapolitan area, 297-
99

Foraminifera (Middle Eocene) fr.
country surrounding the Dardan-
elles, 288-89, 292-95 & pl. xxv.

Foreign Correspondents elected, eviii,
ex—cxl ; number of, x, xxi; list of,
XXV;

Forests, submerged, xeviii-cii.

Forrest Reef (B.C.), 389.

Foster, C. Le Neve, decease an-
nounced, cix.

Fox Tarn (Scawfell), quartz-porphyry
of, 85.

Fractures in the Neapolitan area, 297
et seqq.

Francis, W., obituary of, lxxviii.

Frith Wood (Cumberland), garnet-
iferous breccia of, 87, 88.

Gaick Burn (Perth), Moine Series in,
410 & pl. xxxv.

Galdar (Grand Canary), palagonite-
tuff of, 473.

Galleny Force (Lake District), chem.
anal. of ‘ streaky’ rock W. of, 96.
Gallipoli Conglomerate, 263, 265;

shells from, 280, 281.

Gallipoli Peninsula (Turkey), Oligoc.
coal-seams, &c. in, 249; marine
post-Plioc. shells from, 278.

Garden Cliff (Gloucest.), correlat. of
Rheetic at, 200.

Garnets in the Borrowdale Volcanic
Series, characters of the, 101-102.
Garnet-bearing rocks, &c. of the Bor-
rowdale Volcanic Series, 70-105
figs. & pls. xiii-xiv (microscop.

sects. ).

Garry River (Perth), flaggy gneisses
in, 401, 404-405 figs.

Garry, C. H., obituary of, Ixxvii.

Gault (Upper) limestone at Barnwell,
360-65.

Gauro, Monte (Italy), yellow tuff-vol-
cano, 307

Grizrn, Sir ARCHIBALD, presides at
Ann. Gen. Meeting, ix; vote of
thanks to, xxiii ; addresses to medal-
lists & recipients of awards, xli
et segg.; obituaries of deceased
Fellows, &c., xlix-Ixxx ; on Conti-

nental Elevation & Subsidence, -

lxxx—civ ; communicates G. de

Lorenzo's paper, 296.

GENERAL INDEX.

493

Geldie Burn (Aberdeen), 415.

Geneva, Lake of, phenomena bearing
upon its age, 316-18.

Geological photographs (Brit. Assoc.),
eviil.

Geological Survey maps presented, ii,
iv, cix, cxi.

Gepp, A., 124.

Gherme Tepé-(Turkey), Cardium pro-
tractum from, 258, 282-83 & pl.
XXlv.

‘Ghosts’ of clastic grains, &c. in
metamorphosed rocks, 18, 161.

Gibraltar, new cave on E. side of,
30-36 figs. & pl. vi (plan &
sects.).

Gilbert’s Bridge (Glen Tilt), sect. at,
descr. 416-20; fig. of same, 446 &
map, pl. xxxiii.

Glacial geology of Tasmania, 37-53
figs. & pls. vii-viii; Glacial (?) red
clay of Dardanelles area, 271-72,
275 & pl. xxiii (map).

Glacier-lakes, ancient shore-lines of,
lxxxv ef segq.

Glen Roy, &e., see Roy, Glen, &e.

Gloucestershire (N.W.), non-sequence
betw. Keuper & Rhetic in, 349-58
w. map & sect.

Glynde (Sussex), Ptychodus decurrens
from, 133-36 fig. & pl. xv.

Gneisses, of East-Central Highlands,
sedimentary origin of, 405.

Goblin Combe (Somerset), igneous
rocks of, 146-47, 150-51; petrology
of same, 152, 154-55 & pl. xvii
(microscop. sects.).

Geettingen (Hanover), Derby earth-
quake recorded at, 225.

Gold-deposits of Barkerville (B.C.) &
vicinity, genesis of, 589-93.

Gorgona Deré (Turkey), Eoc., &c.,
of, 245; measured sect. at, (table ii)
273; Sarmatice freshwater fossils
from, 283-85 & pl. xxiv; Cladocora
from, 290 & pl. xxiv.

Gormanston Moraine (Tasmania), 45
46 ; views of, pl. viii.

Gough’s Cavern (Cheddar), human
remains found in, 335-48 figs. &
pl. xxix.

Granophyres of Blea Crag, 72 e¢ segq.
& pl. xiii; chem. anal. of same, 75;
granophyre nr. Criscliffe Knotts &
Lingmell, &e., 80, 81.

Granulitiec structure,
Moine Gneisses, 406.

Great Crag (Dock Tarn), banded ash
& .garnetiferous intrusive rock at,
92 fig.

Green, A. H., quoted, 125-26.

so-called, of

494 GENERAL INDEX.

Green Beds of Loch-Lomond district,
14, 15, 22.

‘Greenstone ’-dykes of Llyn Padarn,
age of, 372-88 & pl. xxxii (micro-
scop. sects.).

Greoeory, J. W., a Contribution to
the Glacial Geology of Tasmania,
37-53 figs. & pls. vii-viil.

Grey gneiss (of Moine Series), 401-
406 et seqgqg; grey tuff, volcanoes
of, in the Phlegrzan area, 310-13.

Greywethers (?) at Wolvercote, 120.

Grits of Pontesford Hill, see Tuffs.

Grossularia in SBorrowdale Vole.
Series, 103.

Gunwalloe (Cornwall), material of
sbingle-beach at, 115, 119.

GwINNELL, W. F., on a small Plesio-
saurus-skeleton fr. the White Lias
of Westbury-on-Severn, 359.

Gyrolepis Albertit, 210.

Habberley Brook (Shropshire), 450,
453.

Hematite in Pontesford-Hill rocks,
475, 478.

Hagio-Strati I. (Levant), hornblende-
andesite of, 253, 277.

Hau, —, 446.

Halleflintas of Pontesford Hill, 464
et segg., & pls. xlii-xlii; use of
term, 467:

Harmanly (Turkey), Oligoc. coal at,
246.

Harrop Tarn (Lake District), quartz-
garnet-porphyrite of, 85-86.

Hatcn, F. H., presents map of S.
Transvaal, cix.

Haughtonite-type of mica in Moine
Gneisses, 407.

Haweswater (Lake District), ‘ streaky’
rocks of the neighbourhood, 98-
101.

‘ Head’ at Prah Sands, 107, 110, 112.

Heatry, Miss M., Notes on Upper
Jurassic Ammonites, w. spec.
reference to Specims. in University
Museum, Oxford: No. I, 54-62
figs. & pls. ix-xil, 63-64.

Hearths, palxolithic (?), at Prah
Sands, 108-109, 111-12.

Hesgpon, W.., cx.

Herm, A., Wollaston medal awarded
to, xli—xlii.

Helicoprion, contrasted w. Edestus, 3,
43-9.

Helvetian-Tortonian of Dardanelles
area, 255 et seqg.; fossils fr. same,
285.

Hiatus in the succession in the East-
Central Highlands, 400, 421, 438-39.

[Nov. 1904,

Highlands (Hast-Central), Moine
Gneisses of the, 400-449 figs. &
pls. xxxlii-xxxvii (map & micro-
scop. sects.).

Hindside (Seathwaite), ‘ streaky’ rock
of, 95 & pl. xiv.

Hoae, A. J.) v.

Hognaston (Derby), effects of earth-
quake on well at, 228-29.

Holaster-subglobosus zone, Ptychodus
decurrens from, 135-386 fig. & pl.
xy.

Houuanp, R., Notes on Nummulites
in the Turkish Rocks described by
Col. English, 292-95 & pl. xxv.

Honestone Group of Highland Series,
400, 416, 419 e¢ segq.

Hora (Turkey), raised beaches at,
263, 264 fig., 265, 268 fig., 269 ;
Plioc. & post-Plioc. shells from,
279, 281; Oligoc. do. from near,
286, 287.

Hornblende-andesites of Dardanelles
area, 253 et seqq., 276, 277.

Hornblende-porphyrite of Bull Crags,
rie

Hornblende-porphyry, fragments in
dyke near Esk House, 78.

Hornblende-schist of Glen Tilt, 445-
45.

Horne, J.[on the Highland sequence],
446-48.

Hornfels-like cale-flintas of the High-
land sequence, 426-27.

Human remains found in Gough’s
Cavern, 335-48 figs. & pl. xxix.

Hourcutnson, <A., Murchison-Fund
award to, xlvi.

Hybodus cloacinus, 209.

minor, 209.

Hydrothermal type of metamorphism
in Loch-Lomond district, 27.

Tce-action in the Thames Valley, 126
et seqgq.

Ice-sheet, ancient Scandinavian, re-
treat of the, Ixxxv e¢ segq.

Ippines, J. P., elected For. Memb.,
Cx:

Iffley (Oxon), implementiferous gravel
at, 129.

Igneous rocks assoc. w. Carb. Limest.
of Bristol district, 137-57 figs. &
pls. xvi-xvii, 158-69 figs.; igneous
rocks of Pontesford Hill, 450-86
figs. & pls. xxxviii—xliii (map, sects.,
& microscop. sects.) ; see also Basalt,
Diabase, Granite, fe.

Tllinois (U.S.A.), Hdestus Heinrichsit

from, il.

Vol. 60.)

Ilmenite as an index of metamor-
phism, 380; ilm. in andesite-lavas
of Pontesford Hill, 470 e¢ segq.

Imbros I. (Levant), coal-seams in, 249 ;
Tert. vole. rocks of, 253, 277;
andesitic hills of, 253, 254 fig. ;
Sarmatic strata of Megalai Kepha-
lai, 259-60 fig.

Implements found in Gough’s Cavern,
343-345 figs. ; sce also Paleoliths.
Implementiferous sections at Wolver-

cote, 120-32 figs.

Infra-Bone-Bed Series (Rheetic), 179.

Inoceramus-limestone (Gault) at Barn-
well, 360-65.

Invercauld Forest (Aberdeen), Moine
Series in, 413, 437.

Inversnaid (Loch Lomond), albite-
gneiss from, 20 & fig.

Inveruglas (Loch Lomond), quartzose
schist from, 19 & pl. ii.

Tron-ores in Llyn-Padarn dyke-rocks,
379-80.

Isacoustic lines of Derby earthquake,
225-24 ; of Caernarvon earthquake,
237 & pl. xx.

Isoseismals of Derby earthquakes, 217-
18, 229-30 map & pl. xix (map); of
Caernarvon earthquake, 234-35.

Italy, Geol. Surv, maps presented, cix.

Japan, Geol. Surv. maps presented,
exil.

Jedikulé (Turkey), non-existence of
Levantine Beds at, 258.

Jupp, J. W., 473.

JuKes-Browne, A. J., 363; the Valley
of the Teign, 319-33 w. maps.

Jura, age of lake-basins between the
Alps & the, 65-69, 316-18.

Jurassic (Upper) ammonites, in Oxford
Univ. Museum, &c., 54-64 figs. &
pls. ix—xil.

Kamir (Turkey), Oligoc. coal near, 249.

Karak Deré (Turkey), post-Plioc.
shells from, 279.

Karrer, F., obituary of, lxiv—Ixv.

Kerassia (Turkey), Sarmatic fresh-
water shells from, 283.

Keshan (Turkey), Oligoc. coal-basin
of, 246-47 ; foss. fr. same, 285 ef
segg. & pl. xxiv; measured sect. at
(table iii), 274; andesites, &e. of,
253, 254, 277; Pontian near, 261,
272; shells fr. same, 281.

Kester Brook (Devon), valley of the,
328, 331.

Keuper, non-sequence betw. Rhetic
and, in N.W. Gloucestershire &
Worcestershire, 349-58 w. map &

sect.

GENERAL INDEX.

495

Kewstoke, see Milton Hill.

Kilacheri (India), ‘deep-sea’ deposit
at, Vil.

Kimeridgian (?) age of Perisphinctes
biplex, 58; (Upper) age of Olco-
stephanus Paliasianus, var. nov., 61.

Kineraig Hill (Fife), seter of, xcu—
X¢iii.

King Valley (Tasmania) glacial de-
posits in, 43-48; origin of King-
River Glacier, 48-49.

Kingrove Farm (Gloucest.), 197.

Kirkfeli (Lake District), dykes of, 80,
82.

Knowle (Wilts), paleoliths from, ex ;
rainwash-drift at, 130.

Kocn, A., elected For. Memb., iv.

Lacustrine conditions at close of
Keuper Epoch, 355, 557.

Lake-basins betw. Jura & Alps, age
of, 65-69, 316-18.

Land, evidence for emergence & sub-
mergence of, lxxxiii—cii.

Land-surface, palzolithic (?) at Prah
Sands, 107 et segq.

Langstrath (Lake District), intrusive
complex of Blea Crag, 70-76 fig. &
pl. xiii (microscop. sects.), w. chem.
anal.

Eapwortu, C., 452, 483; [letter o1
farewell as President], ix, ev; [on
Pontesford-Hill rocks], 485.

Lassington (Gloucest.), Rhetic, &c.
at, 352-53.

Lavas assoc. w. Carb. Limest. of
Bristol district, 140 ef segg., 151-54
& pl. xvii (microscop. sects.) ; an-
desitic, of Pontesford Hill, 470-72
& pl. xliii.

Lesour, G. A. L., Murchison medal
awarded to, xlii-xliv.

Lemmon R. (Devon), ancient course
of the, 328-29, 331.

Leny Grits, 13, 15-16.

Lestey, J. P., obituary of, xlix—lv.

Leucotephrite of Avernus, 309, 312-

Levantine formation, non-existent at
Jedikulé, &c., 258.

Level, changes of, in Dardanelles
area, 261 et segg., 272-73 & table i;
in Neapolitan area, 297-98.

Library, lists of donors to, xiv—xx;
progress of new Card-Catalogue,
Xiv.

Library & Museum Committee, report
of, Xli—xiv.

Lieutroot, Miss M., 456.

Lilliput, sect. fr. bridge to nr. Chip-
ping Sodbury Station, 198; see also
Chipping Sodbury.

496

Lima valoniensis, 202.

Limestones in Aberfoil-Slate Group,
28, 29; relations of limest. to
basalt at Spring Cove, 160 e segq.,
164 et segg. figs.; of East-Central
Highlands, 417 ef segqg., 425, 426
et seqg.; see also Carboniferous
Limestone.

Limpsfield Common (Surrey), ice-
drift at, 150.

Linda Valley (Tasmania), glacial de-
posits of, 45-48.

Lithophyses in Pontesford-Hill rocks,
see Pyromerides.

Llyn Padarn (Caernarvon), age of the
dykes of, 372-88 & pl. xxxii (micro-
scop. sects.).

Loch- Lomond district (Scotland),
metamorphism in, 10-29 figs. &
pls. 1i-v (microscop. sects.).

Lochnagar Granite, Moine Gueisses
of area west of the, 412-13; in-
trusion producing no effect on
Highland rocks, 442.

Lomas, J. [on faulted slate fr. the
vole. slates of Ulpha]., v.

Longmyndian of Pontesford area, 450,
453.

Lorenzo, G. pg, the History of Vol-
canic Action in the Phlegrean
Fields, 296-315 & pls. xxvi-xxviii
(maps & sects.).

Lucerne, Lake of, its parallelism w.
Lake of Geneva discussed, 317, 318.

Lunn, —-, 417.

Lutetian of the district surrounding
the Dardanelles, 244-46; foss. fr.
same, 288-95 & pls. xxiv—xxv.

Lyd or Lyd’s Hole (Shropshire), 450,
451.

Lye. Geological Fund, awards from,
XXXiL.

Lyetu medallists, list of, xxxi.

Lyell, Mt. (Tasmania), glaciated area
around, 49-47 & pl. vii (map).

Lyrcea Bonelli, 281 & pl. xxiv.

McManoy, Mrs., resolut. of sympathy
with, ey.

Mactra podolica, 282 & pl. xxiv.

Mactra-limestones of Dardanelles
area, 255 et seqq.

Magnetite, peroxidized needles of,
152, 153.

Main or Blair-Atholl Limestone, 426.

Maitos (Dardanelles), ancient river-
channel at, 264 fig., 265.

Mall, the (London), ‘ palzofractured’
flint from, ii.

Mammalian remains

in Gough’s
Cavern, 337, 346.

GENERAL INDEX.

[ Noy. 1904,

Man, remains of, found in Gough’s
Cavern, 335-48 figs. & pl. xxix.

Manganiferous ash in the Phlegrzan
area, 309.

Map of Loch-Lomond district, 25 ;
of N.W. Tasmania, 50; of glaciated
area around Mt. Lyell (Tasm.),
pl. vii; of S.W. Cornwall, 115; of
Middle Hope or Woodspring, 140;
illustrat. distrib. of Carb. vole.
rocks in Bristol district, pl. xvi; of
Derby earthquake of May 3rd, 1903,
230; of D. e. of March 24th, 1903,
pl. xix; of Caernarvon earthquakes
of June 19th, 1903, 239 & pl. xx;
(geol. & topogr.) of country sur-
rounding the Dardanelles, pls. xxi-
xxiii ; (geol.) of the Bay of Naples,
pl. xxvi; of the Phlegrzan Fields,
pl. xxviii; of the drainage-area of
the Teign, 320; of Dunsford district,
327; of Ashburton district, 329;
(geol.) of N.W. Gloucestershire &
Worcestershire, 350; of Llyn-
Padarn area, 376; of East Central
Highlands, 402; (geol.) of Glen
Clunie, 422 ; of Gilbert’s Bridgearea,
pl. xxxiii; of Pontesford Hill,
pl. xxxviii.

Maps presented, ii, iii, iv, cviil, cix,
exi, exii.

‘Mappamonte’ (grey tuffy material),
309.

Marble Quarry (Glen Tilt), sect.
deser., 418-20; line of erosion in
Moine Gneisses below, 430 fig., 431.

Marl Cliff (Worcest.), Rheetic, &c. at,
302.

Marlborough (Wilts), palzoliths from,
cx.

Marmora, Sea of, geol. of country sur-
rounding the, 243 e segq., figs. &
pls. xxi-xxill (maps).

Marr, J. E., elected President, xxiv;
receives Wollaston-Fund award for
Miss E. M. R. Wood, xlv; com-
municates the late E. E. Walker’s
paper, 70.

Marston-Common Farm (Derby),
rocks fr. well-sinking at, 367-68.
Martin, E. A., exhibits flint w. plant-

remains, Vl.

Masatly (Turkey), Oligoc. coal, &e.
at, 246; Anthracotherium, &c. from,
285-87 & pl. xxiv.

‘Massive-pavement’ type of Moine
Gneisses, 412.

Mar ey, C. A., Lyell-Fund award to,
xlvii—xlviii.

Mavris I. (Marmora), 270; post-
Plioe. shells from, 279.

Vol. 60.]

Medals, electrotypes of, xiii.

Mediterranean shell-beaches at Hora,
&e., 268 fig., 269-70.

Megalai Kephalai (Imbros), Sarmatic
strata of, 259-60 fig.

Melania cf. Escheri, 283 & pl. xxiv.

Melanopsis costata, 254 & pl. xxiv.

— ef. fusiformis, 286-87.

incerta, 283 & pl. xxiv.

Metamorphism in the Loch-Lomond
district, 10-29 figs. & pls. ii-v
(microscop. sects.) ; metamorphism
of vole. rocks of the Borrowdale
Series, 102-104.

Metoposaurus diagnosticus (?), 208-
209.

Mezzogiorno (Italy), yellow tuff-vol-
eano, 805.

Mhaire, Glen (Perth), Moine Series
of, 418.

Mica-films in Moine Gneisses, 403,
407, 411 ez seqq., 434.

Mica-porphyrite ur. Criscliffe Knotts,
79, 82.

Mickle Moss (Haweswater), rhyolite
of, 90.

Microcline, in Moine Gneisses, 406,
407, 408, 410 ez seqq.

Middle Hope (Somerset), igneous
rocks at, 139-44 figs.; petrology
of do., 153 e¢ seqg. & pl. xvii
(microscop. sects.).

Millstone Grit, secondary growth of
quartz in, 370.

Mitne seismograph, Derby earth-
quake recorded by, 222-23; Caern-
aryon earthquake recorded by, 235,
257.

Milton Hill (Somerset), igneous rocks
at, 145-46, 149-50; petrology of
do., 153 & pl. xvii.

Mines, Derby earthquake observed in,
227-28; Caernarvon earthquake
do., 238.

Miocene of the district surrounding
the Dardanelles, 252 fig., 255-61
fig., 266 fig.; foss. fr. same, 281-85
& pl. xxiv.

Miseno, Cape & Porto di (Italy), yel-
low tuff-voleano, 507.

Mitcham (Surrey), palzoliths from, v.

Modiola minima, 204.

sodburiensis, sp. nov., 203 &
pl. xviii.

Moine Gneisses of the East-Central
Highlands & their position in the
Highland sequence, 400-49 figs. &
pls. xxxiii-xxxvii (map &microscop.
sects.).

Mollusca, typical Rhetic, ranges of,
200, 206; see also Anomia.

GENERAL INDEX.

497

Moncxton, H, W., cv.

Monkey’s Quarry (Gibraltar), new
cave at, 30-36 figs. & pl. vi (plan &
sects. ).

- Monotis decussata, zone of, 189.

Montagna Spaccata or Cleft Moun-
tain (Italy), 312.

Morean, C. Luoyp (& S. H. Rey-
NoLDs), the Igneous Rocks asso-
ciated with the Carboniferous Lime-
stone of the Bristol District, 137—
56 figs. & pls. xvi-xvii.

Mosses, from peat at Wolvercote,
124-25.

Mountain-Limestone, quartzite-dykes
in, nr. Snelston, 364-71 & pls. xxx-
xxxi; see also Carboniferous Lime-
stone.

Movements of earth’s crust & changes
of level, civ; see also Earth-move-
ments.

Morcutson Geological Fund, list of
awards, xxx.

Morcuison medallists, list of, xxix.

Museum (annual report), xiv.

Museum Breccias of the Phlegrean
Fields, 302-303.

Myophoria postera, 204.

Myrica lignitum (2), 288.

Myriophyto (Turkey), Mioc. of, 256,
289.

Naiadita-Beds at Redland, 171 e
segg.; at Stoke Gifford, 176, 195;
at Cotham Road, 177, 178; at
Aust, 178, 179; conditions of de-
position of, 184.

Names of Fellows read out, exi-exii.

Naphtha in Sarmatic strata of Dar-
danelles area, 259.

Naples (Italy), origin of Bay of, 297-
300; section at Royal Gardens,
deser., 300.

Natnuorst, A. G., Lyell medal awarded
to, xliv—xlv.

Neolithic age of human remains fr,
Gough’s Cavern asserted, 347-48 ;
Neol. remains at Wolvercote, 120,

Nettlebank (Staffs), Hdestus from, 1 e¢
segq.

New Guston Mine (Colorado), exem-
plification of secondary enrichment
in, 393.

Newbridge Hill (Somerset), Rhetic
Bone-Bed (?) at, 214,

Newton, E. T. [exhibits implemts. fy.
N. Carolina], vi; on the Occurrence
of EHdestus in the Coal-Measures of
Britain, 1-8 figs. & pl. i.

Newton, R. B., Noteson post-Tertiary
& Tertiary Fossils obtained by Col.

498

English fr. the District surrounding
the Dardanelles, 277-92 & pl. xxiv.

Nicuouison, Sir CuARtes, obituary of,
Ixxy.

Nisida I. (Italy), yeliow tuff-volcano,
305.

Nodular rock of Pinnacle Howe, &c.,
99; nodular structure of Northern
Rhyolite of Pontesford Hill, 457-
63 figs. & pls. xl-xli.

Non-sequence betw. Keuper & Rhetic
in N.W. Gloucestershire & Worces-
tershire, 349-58 w. map. & sect.

Northern Drift at Wolvercote, &c.,
125-27.

Northern Rhyolite of Pontesford
Hill, 454, 455-68 figs., pls. xl-xli, &
chem. anals.

Norton (Gloucest.), Rheetic, &e. at,
349.

Number of Fellows, &c., ix—x, xxi.

Nummulites distans, 293-94 & pl. xxv.

Dufrenoyi, 292-93 & pl. xxv.

— Heberti (?), 294.

variolaria (2), 294.

Nuovo, Monte (Italy), 312, 313.

Obituaries, xlix—lxxx.

Obsidian-Cliff (U.8.A.), lithophyses
compared w. those in artificial
slag, 461.

Obsidian-dykes of Imbros, 253.

Olcostephanus Pallasianus, var. nov.,
60-61 fig. & pl. xii.

Old Red Sandstone unconformably
overlain by Rheetic Black Shales,
nr. Chipping Sodbury, 196 fig.,
197, 218.

Oligocene of the district surrounding
the Dardanelles, 246-50 fig., 252
fig.; foss. fr. same, 285-88 &
pl. xxiv; Oligoc. age of the present
river-system of Devon, 323 et seqq.

Olivine-b: salts of Goblin Combe, &c.,
152 & pl. xvii; of Spring Cove, 158
et seqgg. figs.; of Dardanelles area,
254, 277.

Olivine-dolerite of Pontesford Hill,
454, 466, 480-82, 483, pl. xiii, &
chem. anal.

Omori horizontal pendulum, record
of Derby earthquake given by, 220
fig., 221-22; do. of Caernarvon
earthquake, 235-37 fig.

Oolitic structure of limest. at Goblin
Combe, Spring Cove, &c., 154, 155,
160 et segq., 164 et seqq.

ee (Discocyclina) dispansa,
294.

(——) papyracea, 294,

GENERAL INDEX.

[ Nov. 1904,

Ore Gap (Bow Fell), breccia of, 77
o7:

Osporn, H. F., elected For. Memb.,

evill.

Osmington (Dorset), Amm. variocos-
tatus from, 11.

Ostrea-Cyrnusii-bed, ny.
270, 278.

Oxford Clay, pittings in, at Wolver-
cote, 121.

Owen, Mt. (Tasmania), glaciation of,
47 ; views of, pl. viii.

Gallipoh,

‘ Paleofractured ’ flint, ii.

Paleoliths fr. Surrey, v; fr. Wilts,
x; (?) of vein-quartz, at Prah
Sands, 108-109 fig., 110 e seggq.;
paleoliths at Wolvercote, 123, 131 ;
two classes of, 129; paleoliths (?)
found in Gough’s Cavern, 343,
345 figs., 546 et seqq.

Paleolithic floor at Prah Sands, 106-
12 figs.; Paleolithic Period, sub-
divisions of, 131, 132.

Palagonite-tuffs of Pontesford Hill,
&e., 464-70 figs., pls. xlii-xlin, &
chem. anal., 472-74.

Paper-Shales, see Black Shales.

Parallel Roads of Glen Roy, &c. con-
trasted w. raised beaches, Ixxxvli
et seqq.

Parallel-banded rocks of Moine Series,
400, 406 et segg., 424-25.

Parker, W. A., 398.

Parkinson, J. [on Pontesford-Hill
rocks], 456 e¢ seqg., 485-86.

Parsons, J., 190.

Pasha Liman I. (Marmora), 243-44.

Passage-rocks of Moine Series, 424 &
pl. xxxvi.

Paulo Liman (Turkey), post-Plioc.
shells from, 279.

Pracu, B. N., 399.

Peartree Hill (Oxon), sect. in Drift at,
descr. & fig., 127, 128.

Peaty, A. K., 30, 35.

Pecien valoniensis, 202 & pl. xviii.

Pecten-valoniensis limestones, at Red-
land, 171 e¢ segg.; at Stoke Gifford,
176; at Cotham Ruad, 177; “at
Aust, 179; condits. of deposition of
P.-v. 1., 184.

Peléan type of eruption, 169.

Penck, A., elected For. Memb., iv.

Penta Palummo (Italy), yellow tuff-
voleano, 305.

Perisphinctes biplex, 57-58 & pl. x;
confused w. P. plicatilis, 62 et seqq.

-—— plicatilis, 55-57 fig. & pl. ix.

— variocostatus, 58-60 fig. & pl. xi.

Vol. do. ]

Perlitic structure in Pontesford-Hill
nodular rhyolites, 458 & pl. xl.

Perowskite in ILlyn-Padarn dyke-
rocks, 580 & pl. xxxii.

Petrography of Loch-Lomond rocks,
15-22 fig. & pls. ii-v; of rocks
fr. district surrounding the Dar-
danelles, 276-77; of igneous rocks
assoc. w. Carb. Limest. of Bristol]
district, 151-55 & pl. xvii.

Phlegrean Fields (Italy), history of
vole. action in, 296-315 & pls. xxvi-
Xxvlli (maps & sects.).

Pholidophorus at base of Black Shales
(Rheetic), 214.

Phonolite of Wolf Rock, Eocene (?)
age of, 117.

Phosphatic nodules in
Gault, 360-61.

Photographs, geological (Brit. Assoc.),
cviii.

Physical geography of Rheetic Period,
179-87.

Piano di Quarto (Italy), 307, 509.

Piano di Teano & di Torre Poerio
(Italy), 309.

Pingscon Fund, see Daniel-Pidgeon
Fund.

Pieman Valley (Tasmania), glacial
deposits in, 51, 52.

‘Pillowy’ basalts of Spring Cove,
159, 162 et segq. figs.

Pink felspathic rock (Moine Gneiss
Series), 416 e7¢ seggq.

Pink-edged gneisses (Moine Gneiss
Series), 407-408, 412 ez segq.

Piperno & pipernoid tuff, phase of
the, 301-302.

Placers (auriferous) of Cariboo, genesis
of, 390 et segg.

Plant-remains in flint, vi; plant-
remains (fr. peat at Wolvercote),
123-25; (Oligoc.) fr. Keshan,
288.

Pratt, 8. S., 399.

Platyenemic tibia found in Gough’s
Cavern, 343-44 figs., 347.

Pleistocene glaciation in Tasmania,
38 et segg.; range of same, 49-52
w. map; Pleistoc. mosses in Wol-
vercote peat, 124-25; Pleistoc. of
district surrounding the Darda-
nelles, 265-72 figs.; foss. fr. same,
278-80; Pleistoc. submarine erup-
tions in the Phlegrzan Fields, 298
et seqgq.

Plesiosaurus cf. bibractensis fr. West-
bury-on-Severn, 359.

Plesiosaurus costatus, 208.

Pleuromya Crowcombeia, 188; zone
of, 189.

Barnwell

GENERAL INDEX.

499

Pieurophorus elongatus, 205-207 fig.

Plicatula cloacina, sp. nov., 202 fig.
& pl. xvili.

Pliocene shelf in W. Cornwall, 116;
Plioe. of district surrounding the
Dardanelles, 261-65 figs. ; foss. fr.
same, 281-84 & pl. xxiv; Plioc.
history of the Phlegrzean area, 298.

Puiummemr, W. E. [on Bidston record of
Derby earthquake], 222-25; [on
do. of Caernarvon earthquake], 235.

Pococg, R. I., 399.

Poggioreale (Italy), yellow tuff-vol-
cano, 306.

Polishing of stones by animal agency,
339.

PoxtiarD, W., quoted, 3; chem. anal.
by, 23, 24.

Pontesford Hill (Shropshire), igneous
rocks of, 450-86 figs. & pls. xxxviii-
xliii (map, sects., & microscop.
sects. ).

Pontian, near Keshan, 261, 272; fess.
fr. Dardanelles area, 281 & pl. xxiv;
see also Miocene.

Ponto-Caspian Lake, history of the,
261 et segq., 272.

Porpiyrite of Buscoe Sike, 77; of
Lingmell, 81; see also Hornblende-
porphyrite, fc.

Posillipo (Italy), yellow tuff-voleano,
306.

Post-Pliocene foss. fr. Dardanelles
area, 278-79.

Potamina Deré (Turkey), Sarmatic
freshwater shells from, 283.

Prah Sands (Cornwall), paleeolithic (?)
floor at, 106-12 figs.

Pre-Cambrian ‘greenstone’ of Llyn
Padarn, 375-77.

Pre-Hocene of the district surround-
ing the Dardanelles, 245-44.

Preis, C. 8. Du Ricns, the Age of
the Principal Lake-Basins between
the Jura & the Alps, 65-66, 68-69 ;
Phenomena bearing upon the Age
of the Lake of Geneva, 316-18.

PrestWwicu medallist, xxxii.

Prinaeue, J., 1, 3.

Prior, G. T., elected Auditor, v.

Progressive metamorphism in the
Loch-Lomond district, 24-25.

Prosodacna cf. stenopleura, 281 &
pl. xxiv.

Psara I. (Levant), absence (?) of vole.
rocks in, 250.

Pteromya Crowcombeia distinct fr,
Pleuromya C., 188.

Ptychodontinz, new sub-family, 135.

Ptychodus decurrens, jaws of, 1383-36
fig. & pl. xv.

500 GENERAL INDEX.

Pyrites, leaching of, & the precipita-
tion of gold, 390-91, 392-93.

Pyromerides of Pontesford Hill, 457-
63 figs. & pls. xl—xli.

Pyroxenes in Llyn-Padarn dyke-rocks,
382-84 & pl. xxxii.

Quarries, Caernarvon
observed in, 238.

Quartz-bleb structure in Moine
Gneisses, 406.

Quartz-diabase of Blea Crag, 73; of
Burtness Combe, 84; in Hawes-
water district, 99.

Quartz-felspar-biotite-granulite, in
Gien Tilt, 417.

Quartz-garnet-porphyrite (passing into
granopbyre), 73-74 & pl. xiti ; chem.
anal, of same, 75; q.-g.-p. of Harrop
Tarn, 85-86; quartz-augite-por-
phyrite in Bowfell area, 78.

Quartz-pebbles in Rheztic Bone-Bed,
origin of, 182.

Quartz-porphyries of Yeastrigg Crags,
78; offshoots of Eskdale Granite,
80, 81, 82; of Fox Tarn, 85.

Quartz-porphyrites, near path to
Scawfell Pike, 79; near Criscliffe
Knotts, 79-80.

Quartzite (the Central Highland),
400, 412 et segg., 423-24, 427 et
seqq.

Quartzite-dykes in Carb.-Limest. nr.
Snelston, 8364-71 & pls. xxx-xxxt.

Quartzose limestone of Snelston, 366.

earthquake

Rainfall, heavy, in Pleistoc. time, 125.

Rainwash-drifts, 130.

Raised beaches, as evidence of emer-
gence, Ixxxiv e¢ seqgg.; distribution
of, in British Is., xciii-xevi; r. b. of
Prah Sands, 106; of Cornish &
Welsh coasts, 110,111; on Turkish
coasts, 263-65 fig., 268 fig., 269-
70.

Ranges of Rhetic mollusca, 200, 206.

Rastauu, R. H., 363.

Rav, H.N., on a Deep-Sea Deposit
from an Artesian Boring at Kila-
cheri, near Madras (‘itle only), viii.

Reaver, T. W., exhibits concretion
fr. Vancouver [., ii.

Red loamy clay (or rubble-drift) of
Dardanelles area, 271-72 & pl. xxiii

(map).
Redland (Bristol), Rhetic at, 170-75.
Reefs, auriferous, of Cariboo, charac-
teristics & origin of, 389-90.
Regulations as to admission of visi-
tors, cvi-cvii; as to exhibits at
Meetings, cxi.

[Nov. 1904,

Rew, C., quoted, 123; on the Pro-
bable Occurrence of an Eocene
Outlier off the Cornish Coast,
113-17 figs.; & E. M. Ret, on
a Probable Paleolithic Floor at
Prah Sands (Cornwall), 106-110
figs.

Renarp, A. F., obituary of, lix-lxiv.

Reynoips, 8. H., Lyell-Fund award
to, xlvi-xlvii; communicates A. R.
Short’s paper, 170; (& C. Luoyp
Morean), the Igneous Rocks asso-
ciated with the Carboniferous Lime-
stone of the Bristol District, 137-
56 figs. & pls. xvi-xvii; (& A.
Vaueuan), the Rhetic Beds of the
South-Wales Direct Line, 194-213
figs. & pl. xviii (fossils).

Rhetie sections in Bristol district
described, 170-79; physical geo-
graphy of Rh. Period, 179-87 ;
stratigraphy of Rh. Series, 187-89;
bibliography of same, 190-92, 201,
212-15; zoning of same, 187-89,
199-201; Rh. of S. Wales Direct
Line, 194-214 figs. & pl. xviii; evid.
for non-sequence betw. Keuper &
Rh., in N.W. Gloucestershire &
Worcestershire, 349-58 w. map
& sect.

Rhyolites fr. Boz Tepé, 276; of
Pontestord Hill, 454, 455-463 figs.
& chem. anal., 476-77 & pls. xl-
dhe

Rhyolite-breccias of Pontesford Hill,
454, 474-76 & pl. xliii.

Rhyolitic rocks of Haweswater dis-
trict, 90, 97; in Lining-Crag &
other breccias, 98.

Ricnarpson, L., 190; award fr.
Daniel-Pidgeon fund to, cix; the
Evidence for a Non-Sequence be-
tween the Keuper & Rheetic Series
in North-West Gloucestershire &
Worcestershire, 349-58 w. map &
sect.

Ridge-&-valley scenery in Braemar
area, 423, 443.

River-bed, ancient, at Wolvercote,
120 et segg. ; view of same, 122.

River-development, see Teign R.

Rosarts, N. F. [on flint-implements
fr. Surrey], v.

Rochdale, sce Sparth Bottoms.

Roches moutonnées in Tasmania, 47,

49, 51.

Roman Campagna, similarity of vole. '

phenomena in, to those of the
Phlegrzan area, 315.

Rosewall Hill (Cornwall), sect. to
Tregonning Hill, 116.

—-_ ss

Vol. 60. |

Rosthwaite Fell (Cumberland), cleaved
garnet-lava of, 88; sect. through
R. F., 89; ‘streaky’ rocks of, 95 &
pl. xiv.

Round-weathering gneisses of Moine
Series, 409, 411, 414 & pl. xxxv.
Roy, Glen (Inverness), orig. of Parallel

Roads of, Ixxxvii—-lxxxix.

Royley-Mine coal-seam, 394.

Rubble-drift, see ‘ Head.’

Rudha Ban (Loch Lomond), albite-
gneiss from, 21 & pl. iv; chem.
anal. of same, 23.

Rudha Dubh (Loch Lomond), chem.
anal. of schistose grit from, 23.

Rudha Mor (Loch Lomond), schistose
grit from, 17 & pl. iii.

Rup er, F. W., elected Auditor, v.

Rysosteus Owent, 208.

St. Erth Valley (Cornwall), diagramm.
sect. across, 116.

Satter, A. E., exhibits specims., &e.
fr. Ascension I., ex.

Samoa (Polynesia), palagonitie rocks
compared w. those of Pontesford
Hill, 473.

San Stefano (Turkey), Sarmatic shells
from. 257, 282, 284 & pl. xxiv.

Santa Teresa (Italy), vulcanetto of,
3li.

Sargodon tomicus, 210.

Sarkeui (Turkey), Eoc., &e. at, 245;
measured sect. at Gorgona Deré
near (table ii), 273; see also Gor-
gona Deré.

Sarmatic sea, geol. vicissitudes of,
256-57 ; foss. fr. Dardanelles area,
282-85 & pl. xxiv; sce also Miocene.

Saurichthys acuminatus, 210.

Saxony, Geol. Surv. maps presented,
eviil.

Schizodus Ewaldi, 201, 208.

Schlenbachia varicosa, zone of, at
Barnwell, 360, 362.

Screes, movement of, & Caernarvon
earthquake, 238.

Secondary enrichment of metalliferous
deposits, 390-91, 593.

Sedgwick, Mt. (Tasmania), glaciation
of, 47.

Seismographic records of Derby earth-
quake, 220 fig., 221-28; of Caer-
narvon earthquake, 235-37.

Serpentines of Dardanelles area, 277.

Seter or rock-shelves of Norway, &c.,
lxxxiv e¢ segg.; originated by marine
erosion, XCili.

Shallow-water conditions of Rhetic
Bone-Bed epoch, &c., 180-81, 186-
8

Shear, effects of, 11-12.
Q)7.G.8. No. 240.

GENERAL INDEX,

501

Suerporn, C. D., x; [on progress of
Library-Catalogue], xiv.

Shineton Shales of Pontesford Hill,
452, 464, 465 (map).

Suort, A. Reypie, a Description
of some Rhetic Sections in the
Bristol District, with Considera-
tions on the Mode of Deposition
of the Rhetie Series, 170-92.

Sicilian foss. fr. Dardanelles area,
280-81 & pl. xxiv ; see also Pliocene.

Silica- percentages in Pontesford -
Hill rocks, 456, 477.

Skull, palzolithic (?) found in Gough’s
Cavern, 342-43 & pl. xxix.

Slag, artificial, complex vesicle in,
461 fig.

Slate, faulted, fr. Ulpha, v.

Smallthorne (Staffs), Hdestus from,
1 et seqq.

Smitu, Cuarues, 102.

Situ, Enear, 280.

Snelston (Derby), quartzite-dykes in
Carb. Limest. near, 364-71 &
pls. ¥¥x—xxxi.

Solfatara (Italy), voleano of, 310-11.

Sottas, W. J., 483; communicates
Miss Healey’s paper, 54.

Sound-phenomena of Derby earth-
quakes, 223-28, 231 ; of Caernarvon
earthquakes, 237-38.

South-Eastern Rhyolite of Pontesford
Hill. 454, 476-78 & pl. xli.

South-Wales Direct Line, Rheaetic of,
194-214 fig. & pl. xviii (fossils).

Sparth Bottoms (Lanes), Eoscorpius
fr. Coal-Measures at, 394-99 figs. ;
sect. at, 395.

Special General Meeting, ev-evi.

Specific gravities of Pontesford-Hill
rocks, 456, +77.

Spheroids in basalt of Pontesford Hill,
478.

Spherules & spherulites in Pontes-
ford-Hill rocks, see Pyromerides.
Spondylus subspinosus, 289 & pl. xxiv.
Spring Cove (Somerset), igneous rocks
at, 145, 149, 158-69 figs.; petro-

logy of same, 152-53 & pl. xvii.

Sprincer, F., elected For. Corresp.,
ex,

Stalagmite, upper, in Gough’s Cavern,
337-38 ; lower, ibid., 339.

Stampian foss. fr. Dardanelles area,
285-88 & pl. xxiv; see also Oligo-
cene.

Static metamorphism, use of term,

78.

Srosss, J. T., 1.

Stoke Gifford (Gloucest.), Rheetie at,
175-76, 195.

Stokes, A. H., 215, 227.

2M

502

Rony Tarn (Lake District), diabases

of, 81.

Storm-deposit, Rhetie Bone-Bed re-
garded as a, 181-82, 186.

Strain-cleavage in Moine Series, 445.

Strand-lines, ancient, of Norway, &c.,
Ixxxiv e¢ seqq.

‘Streaky’ rocks of the central Lake
District, 89-98 figs. & pl. xiv
w. chem. anal. ; of Haweswater Dis-
trict, 98-101.

Striated boulder fr. Scilly Is., evi,
118; fr. Gormanston Moraine
(Tasm.), 44 fig., 45.

Striations due to sand-blast, 34.

Struan (Perth), Moine Gneisses of
the district, 401-10 figs. & pl. xxxiv ;
do. of area north of same, 410.

Sty-Head Tarn, ‘streaky’ rock on
path betw. Seathwaite and, 96-97 &
pl. xiv.

Subaérial eruptions in the Phlegrean
area, 308 e¢ segq., 314.

Submarine land-valleys, xevii-xcviii ;
submarine origin of volcanic rocks
at Spring Cove, &c., 156, 164, 168,
169; submarine eruptions in the
Phlegrzan area, 301-807.

Submerged forests, xcviii-cii; sub-
merged land-valleys, xevii—xcviii.

Submergence (& emergence) of land,
lxxxiii-civ; in Dardanelles area,
271.

Subsidence (& elevation), continental,
Ixxx-civ.

Sulphidic ores of Cariboo, 389.

Sunningdale (Berks), flint w. plant-
remains from, vi.

Sutcuirre, W. H. (& W. Batpwiy),
Eoscorpius sparthensis, sp. nov.,
from the Middle Coal-Measures of
Lancashire, 394-99 figs.

Sydney Cove (Cornwall),
descr. & fig., 106-108.

Synclines in the Loch-Lomond dis-
trict, 14; in N.W. Gloucestershire
& Worcestershire, 355 et segq.

sect. at,

Talargoch (Flint), quartzite-dyke at,
369.

Tapes Calverti, sp. nov., 278-79.

Tarf, Glen (Perth), Moine Series in,
411, 439-40 & pl. xxsiv.

Tasmania, glacial geology of, 37-53
figs. & pls. vii—viil.

Tehardak (Turkey), post-Plioc. of,
269-70 ; shells fr. same, 278, 279.
Tea-Green Marls in N.W. Gloucester-
shire & Worcestershire, 349 ef segq.

‘Tea-leaf’ structure in clay, 131.

GENERAL INDEX.

[Nov. 1904,

Tray, J. J. H., votes of thanks to,
xxiii; receives Wollaston Medal
for A. Heim, xli.

Teign R. (Devon), geol. history of the
valley, 319-34 w. maps.

Teke-Keui (Turkey), Pontian shells
from, 281.

Tekfur Dagh (Turkey), coast-cliffs of
the, 247-49 & fig.

Tenedos I. (Levant), 243, 255.

Thames Valley, ice-action in, 126 e¢

seqq:

Tose Heath (Surrey), paleolith
from, v.

Thrust-plane structure in
Gneisses, 411.

Tibia, platyenemic, found in Gough’s
Cavern, 343-44 figs., 347.

Tilt of the ground, its effect on drain-
age-systems, 325, 334.

Tilt, Glen (Perth), Moine Gneisses, &c.
of surrounding area, 400 et segq.;
view in river-bed, 404; line of
erosion in Moine Gneisses, 430 fig.,
431.

Time-relations of sound & shock in
Derby earthquake, 226.

Transvaal (S.) geol. map presented,
Gin

Tregonning Hill (Cornwall), sect. to
Rosewall Hill, 116.

Tremadoc (Caernarvon), age of the
sills of, 388.

Trochocyathus sp. (Lutetian), 290.

Trust-funds, statement of, xxxvuii-
XXXxIX.

Tuffs assoc. w. Carb. Limest. of
Bristol district, 140 et segg., 154-55
& pl. xvii, 159 et seq. figs. ; tuffs
of Dardanelles area, 254, 276;
pipernoid, 301-302; of the Phle-
grean Fields, yellow, 305-307 ;
grey do., volcanoes of, 310-13; of
andesite-group of Pontesford Hill,
454, 463-74 figs. pls. xlii—xlili,
& chem. anal.

‘Tuff-porphyroid’ of Rosthwaite Fell,
95 & pl. xiv.

Tourcuer, J. W., 213.

Twin-chlorite Rock of the Hast-Cen-
tral Highlands, 425, 427.

Tzenguerli Deré (Turkey), Mioc. &
Eoe. fossils from, 285, 288 e¢ segg.
& pl. xxiv.

Moine

Ulpha (Cumberland), faulted slate
from, Vv.

Underground water, effects of Derby
earthquake on, 228-29.

Unich, Allt (Aberdeen), 412, 436.

Unio Delesserti, 283 & pl. xxiv.

Vol. 60. ]

Uphill (Somerset), igneous rocks of,
146, 150.

Uralite, conditions of development of,
384.

Uralite-diabase nr. Kirkfell Tarns,

82.

Uriconian of Pontesford Hill, 451,
452.

Ussurr, W. A. E., 330.

Valleys extending beneath the sea,
xevii—xceviii.

Vancouver I. (B.C.), concretion from,
exhibited, ii.

Variolitic basalt of Spring Cove, 152-
53 and pl. xvii, 157, 165.

Vaucuay, A., 189- 90; [sequence of
Carb. Limest. Series], 147-48, 149,
Eos (& S:. H. ReryNoups), the
Rhatie Beds of the South-Wales
Direct Line, 194-213 fig. & pl. xviii
(fossils).

Vein-quartz, implements (?) of, at
Prah Sands, 108-109 fig., 110 e¢
seqq.

Velocity of transmission of Derby
earthquake, 223.

Vernitza (Turkey), Eocene of, 246;
foss. fr. same, 288, 290 & pl. xxiv,
292-95 & pl. xxv.

Vesicle, complex, in artificial slag, 461
fig.; see also Pyromerides.

Vesicular lavas of Little Birkhouse
Hill, &e., 99; of Spring Cove, 163.

Vicary, W.. obituary of, Ixxvi.

Vindobonian fossils fr. Dardanelles
area, 285; see also Miocene.

Visitors, regulations as to admission
of, cvi-evii.

Voleanic action in the Phlegreean
Fields, history of, 296-315 & pls.
XXVi-xxvili (maps & sects.); rocks,
Tertiary, in the Dardanelles area,
252-55 fig., 276-77; see also Bor-
rowdale, Teneous, §c.

Volcanoes of concentric accumulation
(vuleani a recinto), 296, 308,
311.

Vomero (Italy), yellow tuff-volcano,
306.

Vuleanicity in the Phlegrean area,
synopsis of, 3135.

Wainlode Cliff (Gloucest.), Rhetic,
&e. at, 349.

Watker, the late E. E., Notes on the
Garnet-bearing & Associated Rocks
of the Borrowdale Volcanic Series,
70-104 figs. & pls. xiii-xiv (micro-
scop. sects.).

GENERAL INDEX.

503

Waker, J. F., exhibits specims. of
Spir ifer, Cxi.

Watter, H. T., 460, 473.

Wan dleValley(Surrey), flint-implemts.
from, v.

Warner, C., 269, 286.

Wasuineton, H. S., elected For. Cor-
resp., CViil.

Water, subterranean, effects of Derby
earthquake on, 928-29, aaa ac

Warts, W. W., receives Lyell-Fund
award for C. A. Matley, xlvii; ex-
hibits Brit. Assoc. geol. photographs,
cvlii; communicates A. J. R. Atkin’s
paper, 389.

Wesster, T. 228.

Westbury -on- Severn (Gloucest.),
Plesiosaurus ef. bibractensis from,
309.

Weston-super-Mare, see Spring Cove.

Whelpside Gill (Helvellyn), vole. ash
from, 98 & pl. xiv.

Whelter Crag (Haweswater), rhyolitic

ash of, 90; chem. anal. of rock from,
96.

Wuire, —. 245, 247.

White I. (Scilly), striated boulder

from, cvi.

White Lias, 185; Plesiosaurus cf. bi-
bractensis from, 359.

Wiecuert pendulum, Derby earth-
quake recorded by, 22

Witett, H., 133.

Williams Creek (B.C.), 392.

Winwoop, Rev. H.H., exhibits ‘paleo-
fractured ’ flint, ii.

Wolf-Rock phonolite, Koc. (?) age of,
jl by és

Wo.taston Donation-Fund, list of
awards, xXVili.

Wo.taston medallists, list of, xxvii.

Wolvercote (Oxon), implementiferous
sections at, 120-32 figs.

Wood, fossil drifted, at Redland,
175.

Woop, Miss EK. M. R., Wollaston-
Fund award to, xly—xlvi.

Woops, H., 363.

Woodspring, see Middle Hope.

Woopwarp, A. S., 190, 399; exhibits
Edestus Heinrichsii fr. Illinois, ii;
on the Jaws of Ptychodus from the
Chalk, 1338-35 fig. & pl. xv; [on
Diplomystus marmorensis, sp. noy.],
284-85 & pl. xxiv.

Worcestershire, non-sequence _ betw.
Keuper & Rhetice in, 349-58 w.
map « sect.

Worm-tracks in Rhetic at Redland,
174.

504

Xenoliths in Blea-Crag rocks, &e., 72
et seqgq.
Xeros, Gulf of (Turkey), 253 et segg.

Yadkin R. (N. Carolina), implemts.
from, vi.
Yeastyrigg Crags (Bow Fell), quartz-
porphyry of 78.
Yellow tuff of the Phlegrzan Fields,
304-307.
Yeo R. (Devon), ancient course of the,
28-29, 331-32.

GENERAL INDEX.

[Nov. 1904.

Zaphrentid-limestonesat Middle Hope,
&e., 140, 148 et seggq.

Zeehan district (Tasmania), glacial
deposits in, 49 et segq.

Zittsei, K. A. von, obituary of, lv-lix.

Zonal bending in the region of the
Alps, 66.

Zoning of the Rhetic Beds in Eng-
land, 187-89, 199 et segg. ; of Carb.
Limest. Series, 147-48, 149, 150.

Zurich, Lake of (Switzerland), age of,
65 et segg.; parallelism w. Lake of
Geneva, 316 e¢ segg.

END OF VOL. LX.

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year. The Annual Contribution may at any time be compounded for by a payment of
Thirty-Five Pounds,

The Fellows are entitled to receive gratuitously all the volumes or parts of volumes
of the Quarterly Journal of the Society that may be published after their election,
so long as their Annual Contributions are paid; and they may purchase any of the
publications of the Society at a reduction of 25 per cent. under the selling-prices.

The Library is open daily to the Fellows between the hours of 10 and 5 (except
during the fortnight commencing on the first Monday in September; see also next
page), and on Meeting-Days until 8 p.m. Under certain restrictions, Fellows are
allowed to borrow books from the Library.

Publications to be had of the Geological Society, Burlington House.

Reduced Price Reduced Prices

TRANSACTIONS. tothe oe TRANSACTIONS. to the ipso

8. d. aside

ES ORAL Gr oda ta cnavsscccveccnevscesescss Es 6 WiGlen Wee Part DY .6 cos oc aiatcessee eee 010 6

EBSA Prion civnac caccsasecnenaccaee 0 4 0 | Le Oa a oF See eee eee oe 010 0
4 Sea ce aeceaedecneaenarcsscon 040

QUARTERLY JOURNAL. (Vols. III to LIX, inclusive.)

Price to Fellows, 13s. 6d. each (Vols. XV, XXIII, XXX, and XXXIV to LIX,
16s. 6d.), in cloth.

CLASSIFIED INDEX TO THE TRANSACTIONS, JOURNAL,

&e., by G. W. Ormzrop, Esq. New Edition, to the end of 1868, with First, Second, and
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GENERAL INDEX TO THE FIRST FIFTY VOLUMES OF THE
QUARTERLY JOURNAL (1815-1894). Part I (A-La). Part IT (Ia~Z).
Price 5s. each. To Fellows 3s. 9d. each. [Postage 3d.]

CATALOGUE OF THE LIBRARY, 1880. (620 pages 8vo.) Price 8s.

To Fellows 5s. [Postage 6d.]

ae

GEOLOGICAL LITERATURE added to the Geological Societys Library
during the years ended December 31st, 1894-1902. Price 2s. each. To Fellows ls. 6d.
each. [Postage 23d. |

LIST OF THE TYPE- AND FIGURED SPECIMENS RECOG-
NIZED BY C. D. SHERBORN IN THE COLLECTION OF THE
GEOLOGICAL SOCIETY, verified and arranged, with additions, by the
Rey. J. F. Buake. 1902. Price 3s. 6d. (bound in cloth), 3s. Od. (in paper wrappers).
To Fellows 2s. Gd. and 2s. 0d. [Postage 3d.]

HUTTON’S ‘THEORY OF THE EARTH,’ Vol. IIL. edited by Sir .
ArcupaLp Geikie, D.C.L., F.R.S. Price 3s. 6d. To Fellows 2s. [Postage 4d.]

THE GEOLOGY OF NEW ZEALAND. Translated by Dr. O. F. Fiscurr,
from the works of MM. Hocustrerrer & Pereruann. With an Atlas of Six Maps.

Fellows may purchase One Copy of this book at 2s.; additional copies will be
charged 4s. [Postage dd.]

LN

5 eee ts ee) ae eS oe Ee | ee er ae - hy
SS ee. ee Oa Tie pete bap Nea
a ies Seo Ree ate
r a jaz eo - > > epee

CONTENTS.

Pages

Proceedings of the Geological Society, Session 1903-1904 ........ cc csceceeseeneee i-vili
PAPERS READ.

Page

1. Mr. E. T, Newton on Edestus in the British Coal-Measures. (Plate I.)......... 1

2. Mr. Cunningham-Craig on Metamorphism in the Loch-Lomond Disirict.
(Plates; FTV -): aie c0 ines pave = duatadatads dnatis vet oOhane eae gee 10

5. Mr. Acland on a New Cave at Gibraltar. (Plate VI.) ............ccccececececeeees 30
4, Prof. Gregory on the Glacial Geology of Tasmania. (Plates VII & VIII.) ... 37
5. Miss Healey on some Upper Jurassic Ammonites. (Plates IX-XII.)
6, Dr. Preller on Lake-Basins between the Jura and the Alps. (Adstract.) ...... 65

7. The late Mr. E. E. Walker on the Garnet-bearing and Associated Rocks of
the Borrowdale Volcanic Series. (Plates XIII & XIV.) .............cccc0ceees ‘ 70

8. Mr. & Mrs. Reid on a probable Paleolithic Floor at Prah Sands

[No. 238 will be published next May. |

a

[The Editor of the Quarterly Journal is directed to make it known to the Public that the a
Authors alone are responsible for the facts and opinions contained in their respective
Papers. |

*,* The Council request that all communications intended for publication by the —
Society shall be clearly and legibly written on one side of the paper only, with © 4
proper references, and in all respects in fit condition for being — 2
at once placed in the Printer’s hands. Unless this is done, it will be in © “|
the discretion of the Officers to returnthe communication to the Author for revision.

The Library and Museum at the Apartments of the Society are open every wea ;
from Ten o’clock until Five, except during the fortnight commencing on the
first Monday in September, when the Library is closed for the purpose ofta
cleaning; the Library is also closed on Saturdays at One p.m. during the 4
months of August and September. It is open until Eight p.m. on the Days of
Meeting for the loan of books, and from Hight p.m. until the close of each
Meeting for conversational purposes only.

LLL Las

Vol. L&. MAY 14th, 1904. No. 238.
Part 2,

THE

QUARTERLY JOURNAL

OF THE

GEOLOGICAL SOCIETY.

EDITED BY

Ee tis

THE ASSISTANT-SECRETARY.

[With Five Plates, illustrating Papers by Dr. A. Smith &

Woodward, Prof. Lloyd Morgan & Prof. Reynolds;-Prof— =

LONDON: National WY
LONGMANS, GREEN, AND CO.
PARIS:—CHARLES KLINCKSIECK, 11 RUB DE LILLE.

SOLD ALSO AT THE APARTMENTS OF THE SOCIETY,
Price Five Shillings.

DR RRR a OOOO

LISt OF THE OFFICERS OF THE
GEOLOGICAL SOCIETY OF LONDON.

~nasnneoeneeeoeeeeere

Elected February 19th, 1904.

WYIYyy vw

President.
John Edward Marr, Sc.D., F.RB.S.

Gice-Prestdents.
Prof. Thomas George Bonney, Sc.D., LL.D., | Edwin Tulley Newton, Esq., F.R.S.

E.R.S., F.S.A.

Sir Archibald Geikie, Se.D., D.C.L., LL.D.,

Sec.R.S.

Horace Bolingbroke Woodward, Esq.,
F.R.S.

Secretaries.

Robert Stansfield Herries, Esq., M.A.

Foreign Secretary.

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

Prof. William Whitehead Watts, M.A.,
M.Sce., F.R.S.

Treasurer.

William Thomas Blanford, 0.1.E., LL.D.,
F.R.S.

COUNCIL.

The Rt. Hon. the Lord Avebury, P.C.,

D.O.L., LL.D., F.R.S., F.L.S.
Francis Arthur Bather, M.A., D.Sc.

William Thomas Blanford, C.I.E., LL.D.

F.R.S.

Prof. Thomas George Bonney, Se.D., LL.D.,

F.R.S., F.S.A.

Sir John Evans, K.C.B., D.O.L., LL.D.,
E.R.S.

Prof. Edmund Johnstone Garwood, M.A.

Sir Archibald Geikie, Sc.D., D.C.L., LL.D.,

Sec.R.S.
Prof. Theodore Groom, M.A., D.Se.
Alfred Harker, Esq., M.A., F.R.S.
Robert Stansfield Herries, Esq., M.A.

Prof. John W. Judd, C.B., LL.D., F.B.S.
Percy Fry Kendall, Esq.
Philip Lake, Esq., M.A.

,| Prof. Charles Lapworth, LL.D., F.R.S.

Bedford McNeill, Esq., Assoc. R.S.M.
John Edward Marr, Sc.D., F.R.S.
Prof. Henry Alexander Miers, M.A., F.R.
Horace Woollaston Monckton, Ksq., F.L.
Edwin Tulley Newton, Esq., F.R.S.
George Thurland Prior, Esq., M.A.
Prof. William Whitehead Watts, M.A.,
M.S8c., F.R.S.
The Rey. Henry Hoyte Winwood, M.A.
Horace Bolingbroke Woodward, Esq.,
F.RBS.

s.
Ss.

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

Assistants in @ffice, Library, and {Museum.

W. Rupert Jones.

Clyde H. Black.

Alec Field.

EVENING MEETINGS OF THE GEOLOGICAL SOCIETY
TO BE HELD AT BURLINGTON HOUSE.
SEsstion 1903-1904.

Wednesday, May

Soe eereseeeseneeeses

a UNE. sis tus keer oan eee

Seer eeeeeeeeeneseeseeeeesesese

25
g*_99%

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

- ADMISSION AND PRIVILEGES

OF
FELLOWS OF THE GEOLOGICAL SOCIETY OF LONDON.

Every Candidate for admission as a Fellow must be proposed by three or more Fellows,
who must sign a Certificate in his favour. The Proposer whose name stands first upon
the Certificate must have a personal knowledge of the Candidate.

Fellows on election pay an Admission-Fee of Six Guineas. The Annual Contribu-
tion paid by Fellows is Two Guineas, due on the Ist of January in every year, and
payable in advance; but Fellows elected after the month of February are subject only
to a proportionate part of the Contribution for the year in which they are elected,
and Fellows elected in November or December pay no Contribution for the current
year. The Annual Contribution may at any time be compounded for by a payment of
Thirty-Five Pounds.

The Fellows are entitled to receive gratuitously all the volumes or parts of volumes
of the Quarterly Journal of the Society that may be published after their election,
so long as their Annual Contributions are paid; and they may purchase any of the
publications of the Society at a reduction of 25 per cent. under the selling-prices.

The Library is open daily to the Fellows between the hours of 10 and 5 (except

_ during the fortnight commencing on the first Monday in September; see also next

page), and on Meeting-Days until 8 p.m. Under certain restrictions, Fellows are
allowed to borrow books from the Library.

Publications to be had of the Geological Society, Burlington House.

Reduced Price Reduced Price

TRANSACTIONS. tothe Ege TRANSACTIONS. to the Bg

et a: oat & d,

“ale 9 SEES SP eee oe Pies) Oe iMobr VAs: Park 2 cK ccc hegateiok ke opetee 010 0

“SLSR 3 See ee Se 0 4 0 Wel. Vill, ‘Part 4 /20.20.5 225, Sere ee 010 0
“ LS DENS BS ie ee eee 0 4 0

QUARTERLY JOURNAL. (Vols. III to LIX, inclusive.)

Price to Fellows, 13s. 6d. each (Vols. XV, XXIII, XXX, and XXXIV to LIX,
16s. 6d.), in cloth.

CLASSIFIED INDEX TO THE TRANSACTIONS, JOURNAL,
&e., by G. W. OrmExop, Esq. New Edition, to the end of 1868, with First, Second, and
Third Supplements to the end of 1889. Price 8s. 6d. To Fellows, 5s.6d. [Postage
5d.|—The First, Second, and Third Supplements may be purchased separately.

GENERAL INDEX TO THE FIRST FIFTY VOLUMES OF THE
QUARTERLY JOURNAL (1845-1894). Part I (A-La). Part IT (Ia-Z).
Price 5s. each. - To Fellows 3s, 9d. each. [Postage 3d.]

CATALOGUE OF THE LIBRARY, 1880. (620 pages 8vo.) Price 8s,
To Fellows 5s. [Postage 6d.]

GEOLOGICAL LITERATURE added to the Geological Society's Library
during the years ended December 31st, 1894-1902. Price 2s. each. To Fellows ls. 6d.
each. [Postage 23d. ]

LIST OF THE TYPE- AND FIGURED SPECIMENS RECOG-
NIZED BY C. D. SHERBORN IN THE COLLECTION OF THE
GEOLOGICAL SOCIETY, verified and arranged, with additions, by the
Rey. J. F. Buaxe. 1902. Price 3s. 6d. (bound in cloth), 3s. Od. (in paper wrappers).
To Fellows 2s. 6d. and 2s. 0d. [Postage 3d.]

HUTTON’S ‘THEORY OF THE EARTH,’ Vol. III., edited by Sir
ArcuipaLp Gerxisz, D.C.L., F.R.S. Price 3s. 6d. To Fellows 2s. [Postage 4d.]

THE GEOLOGY OF NEW ZEALAND. Translated by Dr. O. F. Fiscuzr,
from the works of MM. Hocusterrer & Perermany. With an Atlas of Six Maps.

Fellows may purchase One Copy of this book at 2s.; additional copies will be
charged 4s. [Postage 5d.]

CONTENTS,

Pages
Proceedings of the Geological Society, Session 1903-1904, including the Pro-
ceedings at the Annual General Meeting, the Anniversary Address, etc.... ix-cviii

PAPERS READ.

Page
9. Mr. Clement Reid on a probable Eocene Outlier off the Cornish Coast ........ 113
10. Mr. A. M. Bell on Implementiferous Sections at Wolvercote .........scccececeees 120

11. Dr. A. Smith Woodward on the Jaws of Ptychodus from the Chalk.
CP late PAV) Se ascasacenceces -stcvnsaeedte S ccatategssahycasavearaecuptaetscches se cnee er eamsee 133

12. Prof. Lloyd Morgan & Prof. Reynolds on the Igneous Rocks associated with
the Oarboniferous Limestone of the Bristol District. (Plates XVI & XVII.) 137

13. Mr. Boulton on the Igneous Rocks at Spring Cove ...........csecsecsecsceseeeeeees 158

14. Mr. Rendle Short on Rbeztic Sections in the Bristol District, and on the Mode
of Deposition of the Bhsstic Series «2. ..2i...s.0.c.cc 000 deans ovsbee ee «codseae eens 170

15. Prof. Reynolds & Mr. Vaughan on the Rhetic of the South-Wales Direct
Sume.\* (CEelate SOVAILE) fe. o.oo cisss caves canteves teal bath oct shaw ese eee 194

16. Dr. Davison on the Derby Earthquakes of March 24th and May 3rd, 1903.
(PIAfie Aa) seeped Sec adl o cesa've see tsnonatsyaaite dapccaee soecec tae) diaet aan Dae eee 215

[The List of Geological Literature for 1903 will be issued shortly.—
No. 239 of the Quarterly Journal will be published next August. |

[The Editor of the Quarterly Journal is directed to make it known to the Public that the
Authors alone are responsible for the facts and opinions contained in their respective

Papers. |

*.* The Council request that all communications intended for publication by the
Society shall be clearly and legibly written:on one side of the paper only, with
proper references, and in all respects in fit-condition for being
at once placed in the Printer’s hands. Unless this is done, it will be in
the discretion of the Officers to return the communication to the Author for revision.

The Library and Museum at the Apartments of the Society are open every Weekday
from Ten o’clock until Five, except during the fortnight commencing on the
first Monday in September, when the Library is closed for the purpose of
cleaning; the Library is also closed on Saturdays at One'p.m. during the
months of August and September. It is open until Hight p.m. on the Days of
Meeting for the loan of books, and from Hight p.m. until the close of each
Meeting for conversational purposes only.

Bt Mea Soy BS Re SD BLS OY CGAY es; BEES AEE eee al tS =
| Vol. LX. AUGUST 15th, 1904. No. 239. :
3 Part 3.
| THE
|
|) QUARTERLY JOURNAL i
:
OF THE ,

;
| GEOLOGICAL SOCIETY.
:

EDITED BY

THE ASSISTANT-SECRETARY.

[With Thirteen Plates, illustrating Papers by Dr. Davison,
Col. English, Mr. R. B. Newton, Mr. R. Holland,
Prof. G. de Lorenzo, Mr. H. N. Davies, Mr. Arnold-
Bemrose, and Mr. J. V. Elsden. | ,

LONDON :

LONGMANS, GREEN, AND CO.
PARIS:—CHARLES KLINCKSIECK, 11 RUE DE LILLE.

SOLD ALSO AT THE APARTMENTS OF THE SOCIETY,

Price Five Shillings.

Oil Ol OO LOLOL GLO OOOO LOLOL OOOO OOOO MOO OOOO NO DDO ws

SOO ore

.
»
=

LIST OF THE OFFICERS AND COUNCIL OF THE ~

~ ee
ry Me
=
4 aq

GEOLOGICAL SOCIETY OF LONDON.

—_—, eee

Elected February 19th, 1904.

Wy yw

PrestVent.
John Edward Marr, Se.D., F.R.S.
Gice-PBresidents.
Prof. Thomas George Bonney, 8c.D.,LL.D., | Edwin Tulley Newton, Esq., F.R.S.
E.R.S., F.S.A. Horace Bolingbroke Woodward, Esq.,
Sir Archibald Geikie, Se.D., D.C.L., LL.D., F.R.S.
Sec.R.S.
Secretaries.
Robert Stansfield Herries, Esq., M.A. | Prof. William Whitehead Watts, M.A.,
| M-Se., F.R.S. .
Foreign Secretary, Creasurer.
Sir John Evans, K.C.B., D.C.L., LL.D., | William Thomas Blanford, C.I.E., LL.D.,
E.R.S., F.L.S. F.R.S.
COUNCIL.
The Rt. Hon. the Lord Avebury, P.C.,| Prof. John W. Judd, C.B., LL.D., F.RS.
D.C.L., LL.D., F.R.S., F.L.S. | Prof, Percy Fry Kendall.
Francis Arthur Bather, M.A., D.Sc. | Philip Lake, Esq., M.A.
William Thomas Blanford, C.I.E., LL.D.,| Prof. Charles Lapworth, LL.D., F.R.S.
FE.R.S. | Bedford McNeill, Esq., Assoc. R.S.M.
Prof. Thomas George Bonney, Se.D., LL.D.,| John Edward Marr, Se.D., F.B.S.
E.R.S., F.S.A. Prof. Henry Alexander Miers, M.A., F.R.S.
Sir John Evans, K.C.B., D.O.L., LL.D.,) Horace Woollaston Monckton, Esq., F.L.S.
F.B.S. | Edwin Tulley Newton, Esq., F.R.S.
Prof. Edmund Johnstone Garwood, M.A. | George Thurland Prior, Esq., M.A.

Sir Archibald Geikie, Se.D., D.C.L., LL.D.,, Prof. William Whitehead Watts, M.A.,

Sec. B.S. | MSce., F.R.S.
Prof. Theodore Groom, M.A., D.Se. |The Rey. Henry Hoyte Winwood, M.A.
Alfred Harker, Esq., M.A., F.R.S. |Horace Bolingbroke Woodward, Esq.,
Robert Stansfield Herries, Esq., M.A. | ERS.

Assistant-Secretarp, Clerk, Librarian, and Curator.
L. L. Belinfante, M.Se.
Agsistants tn @ffice, Library, and Huseum.

W. Rupert Jones. Clyde H. Black.
Alec Field.

STANDING REFERENCE COMMITTEE.
Dr. J. E. Marr, President.
R. S. Herries, Esq. By oe
Prof. W. W. Watts. } ag sa

Dr. F. A. Bather. Prof. J. W. Judd.
Dr. W. T. Blanford. Prof. H. A. Miers.
Prof. T. G. Bonney. Mr. E. T. Newton.
Prof. E. J. Garwood. Mr. A. C. Seward.

Lj Sir Archibald Geikie. Mr. H. B. Woodward.

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

Session 1904-1905.

1904. 1905.
Wednesday, November ......... 9*—23* | Wednesday, March ............ 8*—_22
” December ......... 21 a AGRA: Oh eset 5*—19
1905. BE: Ey Pe Suen 10*—24
; ee
Wednesday, January ............ 4*_]8* 4 bee: Pitas > Lite

“ Feb. (Anniversary,
Friday, Feb.17th) 1*—22*
[Business will commence at Eight o’ Clock precisely each Evening.]
The dates marked with an asterisk are those on which the Council will meet.

4
ve
>|
t

3
+

wr .

ee AS ee ut es | v ~ & ) na , al

ADMISSION AND PRIVILEGES
OF

FELLOWS OF THE GEOLOGICAL SOCIETY OF LONDON.

Every Candidate for admission as a Fellow must be proposed by three or more Fellows,
who must sign a Certificate in his favour. The Proposer whose name stands first upon
the Oertificate must have a personal knowledge of the Candidate.

Fellows on election pay an Admission-Fee of Six Guineas. The Annual Contribu-
tion paid by Fellows is Two Guineas, due on the Ist of January in every year, and
payable in advance; but Fellows elected after the month of February are subject only
to a proportionate part of the Contribution for the year in which they are elected,
and Fellows elected in November or December pay no Contribution for the current
year. The Annual Contribution may at any time be compounded for by a payment of
Thirty-Five Pounds.

The Fellows are entitled to receive gratuitously all the volumes or parts of volumes
of the Quarterly Journal of the Society that may be published after their election,
so long as their Annual Contributions are paid; and they may purchase any of the
publications of the Society at a reduction of 25 per cent. under the selling-prices.

The Library is open daily to the Fellows between the hours of 10 and 5 (except
during the fortnight commencing on the first Monday in September ; see also next
page), and on Meeting-Days until 8 p.m. Under certain restrictions, Fellows are
allowed to borrow books from the Library.

Publications to be had of the Geological Society, Burlington House.

Reduced Price | Reduced Price

TRANSACTIONS. tothe Fellows. | TRANSACTIONS. to the apd

5 8. a, &. d,

Vyas a FA] 1 esse. 0 Oly VAL IR ATG) vececsesaccnsscuceus aontentos 010 0

Te AUT 9g ed ae 0 4 0 WoL GV ES Parti 4s yc acccsoccacahoaseesensacct a 010 0
~ AACR c cee dete oa. cee iicdc ae ocecendsens> 0 4 0

QUARTERLY JOURNAL. (Vols. III to LIX, inclusive.)

Price to Fellows, 13s. 6d. each (Vols. XV, XXIII, XXX, and XXXIV to LIX,
16s. 6d.), in cloth.

CLASSIFIED INDEX TO THE TRANSACTIONS, JOURNAL,

&e., by G. W. OrmeErRop, Esq. New Edition, to the end of 1868, with First, Second, and

Third Supplements to the end of 1889. Price 8s. 6d. To Fellows, 5s. 6d. [Postage
5d.|—The First, Second, and Third Supplements may be purchased separately.

GENERAL INDEX TO THE FIRST FIFTY VOLUMES OF THE
QUARTERLY JOURNAL (1845-1894). Part I (A-La). Part II (La-Z),
Price5s, each. To Fellows 3s. 9d. each. [Postage 3d.]

CATALOGUE OF THE LIBRARY, 1880. (620 pages 8vo.) Price 8s,
To Fellows 5s. [Postage 6d.]

GEOLOGICAL LITERATURE added to the Geological Society’s Library
during the years ended December 31st, 1894-1903. Price 2s. each. To Fellows ls. 6d.
each. {Postage 23d. |

LIST OF THE TYPE- AND FIGURED SPECIMENS RECOG-
NIZED BY C. D. SHERBORN IN THE COLLECTION OF THE
GEOLOGICAL SOCIETY, verified and arranged, with additions, by the

‘Rey. J.F. Brake. 1902. Price 3s. 6d. (bound in cloth), 3s. Od. (in paper wrappers).

To Fellows 2s. 6d. and 2s. Od. [Postage 3d.]

HUTTON’S ‘THEORY OF THE EARTH,’ Vol. III., edited by Sir
ArcuIBaLp Gerkie, D.C.L., F.R.S. Price 3s. 6d. To Fellows 2s. [Postage 4d.]

THE GEOLOGY OF NEW ZEALAND. Translated by Dr. O. F. Fiscusr,
from the works of MM. Hocusterrer & Perermann. With an Atlas of Six Maps.

Fellows may purchase One Copy of this book at 2s.; additional copies will be
charged 4s, [Postage 5d.]

CONTENTS.

Pages

Proceedings of the Geological Society, Session 1903-1904 ...........ccccceeeeeees cix—cxii
PAPERS READ.

Page

17. Dr. Davison on the Caernarvon Earthquake of June 19th, 1903, and its —

Accessory Shocks.:,/(Plate"KX.) 2.icc ce ceiecs deste dhentne aaeteeeee 233

18. Col. English on Eocene and later Formations surrounding the Dardanelles,
with Appendices by Dr. Flett, Mr. R. B. Newton, and Mr. R. Holland.

(Biates AAT ON KY 5) ga cva. sege sens qe agehatparesseyecctee tesa, agee eee eee ee 245
19. Prof. De Lorenzo on the History of Volcanic Action in the Phlegrean Fields.

(Plates ARV I- ANVIL.) evita eaves cesels slacy des cucteviebs cannes ee 296
20. Dr. Preller on the Age of the Lake of Geneva. (Adstract.) ......c.ccceccececeee 316
21. Mr. Jukes-Browne on the Valley of the Teign .........60. ..cceccsecececcoccssueenee 319
22. Mr. H. N. Davies on Human Remains in Gough’s Cavern, Cheddar. (Plate

RAE enka czdn te none sane denn sibs 2 Canta olde an2otontsn cal acaiee ves is oak ae aoe ern 335

23. Mr. L. Richardson on a Non-Sequence between the Keuper and the Rheetic... 349
24, Mr. W. F. Gwinnell on Plesiosaurus from the White Lias of Westbury-on-

Severs” (Abstract) 3.5.2 oon cra peannevnckctods. (aes eee et 359
25. Mr. Fearnsides on Upper Gault Limestone at Barnwell .....................ceeeee 360
26. Mr. Arnold-Bemrose on Quartzite-Dykes in Mountain-Limestone. (Plates

Pe A RR tec de nae dic acuanes bode ape teens ucegiaes pease seus aa 364
27. Mr. Elsden on the Age of the Llyn-Padarn Dykes. (Plate XXXII.) ......... 372

[No. 240 of the Quarterly Journal will be published next November. |

[The Editor of the Quarterly Journal is directed to make it known to the Public that the
Authors alone are responsible for the facts and opinions contained in their respective
Papers. |

*,* The Council request that all communications intended for publication by the
Society shall be clearly and legibly written on one side of the paper only, with
proper references, and in all respects in fit condition for being
at once placed in the Printer’s hands. Unless this is done, it will be in
the discretion of the Officers to returnthe communication to the Author for revision.

The Library and Museum at the Apartments of the Society are open every Weekday
from Ten o’clock until Five, except during the fortnight commencing
on the first Monday in September, when the Library isclosed for
the purpose of cleaning; the Library is also closed on Saturdays
at One p.M. during the months of AugustandSeptember. It is open
until Eight p.m. on the Days of Meeting for the loan of books, and from Hight
p.M. until the close of each Meeting for conversational purposes only.

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No. 240,

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THE

NOVEMBER 23rd, 1904.

QUARTERLY JOURNAL

OF THE

GEOLOGICAL SOCIETY.

EDITED BY

THE ASSISTANT-SECRETARY.

[With Eleven Plates, illustrating Papers by Mr. Barrow
and Prof. Boulton. |

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PARIS:—CHARLES KLINCKSIECK,\11 RUE DE LILLE. the )

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LIST OF THE OFFICERS AND COUNCIL OF THE

GEOLOGICAL SOCIETY OF LONDON.

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

ices Presidents.

Prof. Thomas George Bonney, Se.D.,LL.D.,

F.R.S., F.S.A.

Sir Archibald Geikie, Sc.D., D.C.L., LL.D.,

Sec.R.S.

Edwin Tulley Newton, F.R.S.
Horace Bolingbroke Woodward, F.R.S.

Secretaries.

Robert Stansfield Herries, M.A.

Foreign Secretary.
Sir John Evans, K.C.B., D.C.L., LL.D.,
E.R.S., F.LS.

Prof. William Whitehead Watts, M.A,,
M.Sce., F.R.S.

Creasurer,

William Thomas Blanford, O.I.E., LL.D.,
PRS:

COUNGIL.

The Rt. Hon. the Lord Avebury, P.C.

D.O.L., LL.D., F.R.S., F.L.S.

Francis Arthur Bather, M.A., D.Sc.

William Thomas Blanford, C.I.E., LL.D.,
E.R.S8.

Prof. Thomas George Bonney, Sc.D., LL.D.,,
F.R.S., F.S.A.

Sir John Evans, K.C.B., D.O.L., LL.D.,
E.R.S.

Prof. Edmund Johnstone Garwood, M.A.

,| Prof. John W. Judd, C.B., LL.D., F.B.S,
| Prof. Perey Fry Kendall.

Philip Lake, M.A.
| Prof. Charles Lapworth, LL.D., F.R.S.

| Bedford McNeill, Assoc. B.S. M.

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

| Prof. Henry Alexander Miers, M.A., F.RB.S.

Horace Woollaston Monckton, F, L. S.
Edwin Tulley Newton, F.R.S.
George Thurland Prior, M.A.

Sir Archibald Geikie, Sce.D., D.C.L., LL.D. | Prof. William Whitehead Watts, M.A.,

Sec.R.S.
Prof. Theodore Groom, M.A., D.Sc.
Alfred Harker, M.A., F.R.S.
Robert Stansfield Herries, M.A.

M.&c., F.R.S.
The Rev. Henry Hoyte Winwood, M.A.
Horace Bolingbroke Woodward, ERS.

Assistant-Secretary, Clerk, Librartan, anv Curator.
L. L. Belinfante, M.Se.

Agsistants tn @ffice, Library, and Mluseum.

W. Rupert Jones.

Clyde H. Black.

Alec Field.

STANDING REFERENCE COMMITTEE.
Dr. J. E. Marr, President.

Mr. R. S. Herries.
Prof. W. W. Watts.

Dr, F. A. Bather.
Dr. W. T. Blanford.
Prof. T. G. Bonney.
Prof. E. J. Garwood.
Sir Archibald Geikie.

\ Secretaries.

Prof. J. W. Judd.
Prof. H. A. Miers.
Mr. E. T. Newton.
Mr. A. C. Seward.
Mr. H. B. Woodward.

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

1904.
Wednesday, November ......... 23*
3 December ......... 7*—21
1905.
Wednesday, January ............ 4*_]8*
is Feb. (Anniversary,

Friday, Feb.17th) 1*—22*

Session 1904-1905.

1905.
Wednesday, March ............ 8*—22
yy girl Siac voneoseane 5*—19
. May roc cdaectaevanere 10*—24
. TUNE ~ chcas aren eae 7*—21*

[Business will commence at Eight 0’ Clock precisely each Evening. |
The dates marked with an asterisk are those on which the Council will meet.

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ADMISSION AND PRIVILEGES

OF
FELLOWS OF THE GEOLOGICAL SOCIETY OF LONDON.

Every Candidate for admission as a Fellow must be proposed by three or more Fellows,
who must sign a Certificate in his favour. The Proposer whose name stands first upon
the Certificate must have a personal knowledge of the Candidate.

Fellows on election pay an Admission-Fee of Six Guineas. The Annual Contribu-
tion paid by Fellows is Two- Guineas, due on the Ist of January in every year, and
payable in advance; but Fellows elected after the month of February are subject only
to a proportionate part of the Contribution for the year in which they are elected,
and Fellows elected in November or December pay no Contribution for the current
year. The Annual Contribution may at any time be compounded for by a payment of
Thirty-Five Pounds,

The Fellows are entitled to receive gratuitously all the volumes or parts of volumes
of the Quarterly Journal of the Society that may be published after their election,
so long as their Annual Contributions are paid; and they may purchase any of the
publications of the Society at a reduction of 25 per cent. under the selling-prices.

The Library is open daily to the Fellows between the hours of 10 and 5 (except
during the fortnight commencing on the first Monday in September; see also next
page), and on Meeting-Days until 8 p.m. Under certain restrictions, Fellows are
allowed to borrow books from the Library.

Publications to be had of the Geological Society, Burlington House.

Reduced Price | Reduced Price

TRANSACTIONS. tothe ieee TRANSACTIONS. to the Pps be

ae B 8. d.

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MMENEED Pari Ec. occapsccccesensiaes-.-cpiee 040 | se 0 aa eo acs esc cceaphesde casies 010 0
- BETH one's can ecccansseenssecccest 0 4 6

QUARTERLY JOURNAL. (Vols. III to LX, inclusive.)

Price to Fellows, 13s. 6d. each (Vols. XV, XXIII, XXX, and XXXIV to LX,
16s. 6d.), in cloth.

CLASSIFIED INDEX TO THE TRANSACTIONS, JOURNAL,
&e., by G.W. Ormerop. New Edition, to the end of 1868, with First, Second, and
Third Supplements to the end of 1889. Price 8s. 6d. To Fellows, 5s.6d. [Postage
5d.]—The First, Second, und Third Supplements may be purchased separately.

GENERAL INDEX TO THE FIRST FIFTY VOLUMES OF THE
QUARTERLY JOURNAL (1845-1894). Part I (A-La). Part II (La-Z).
Price 5s. each. To Fellows 3s. 9d. each. [Postage 3d.]

CATALOGUE OF THE LIBRARY, 1880. (620 pages 8vo.) Price 8s,
To Fellows 5s. [Postage 6d.]

GEOLOGICAL LITERATURE added to the Geological Society's Library
during the years ended December 31st, 1894-1903. Price 2s. each. To Fellows 1s. 6d.
each. [Postage 23d. ]

LIST OF THE TYPE- AND FIGURED SPECIMENS RECOG.-
NIZED BY C. D. SHERBORN IN THE COLLECTION OF THE
GEOLOGICAL SOCIETY, verified and arranged, with additions, by the
Rey. J. F. Brake. 1902. Price 3s. 6d. (bound in cloth), 3s, Od. (in paper wrappers).
To Fellows 2s. 6d. and 2s. 0d. [Postage 3d.]

HUTTON’S ‘THEORY OF THE EARTH,’ Vol. III, edited by Sir
ARCHIBALD Garkie, D.C.L., F.R.S. Price 3s.6d. To Fellows 2s. [Postage 4d.]

THE GEOLOGY OF NEW ZEALAND. Translated by Dr. O. F. Fiscugr,
from the works of MM. Hocusterrer & Perermann. With an Atlas of Six Maps.

Fellows may purchase One Copy of this book at 2s.; additional copies will be
charged 4s. [Postage 5d.]

a
T :
CONTENTS,
PAPERS READ.
Page
28. Mr. A. J. R. Atkin on the Genesis of the Gold-Deposits of Barkerville and
the V LITA by © «ss nccsoncedtaicosgeeenc oiadauand tenet aes Gar aneeeee Ee en ane ee ee 389

29. Messrs. Baldwin & Sutcliffe on Loscorpius sparthensis .......6..eccesveceenneeeenees 394

30. Mr. Barrow on the Moine Gneisses of the East-Central Highlands and their
Position in the Highland Sequence. (Plates XXXIII-XXXVII.) ............ 400

31. Prof. Boulton on the Igneous Rocks of Pontesford Hill. (Plates XXXVIII-
ME TET)): = vowcesceundas ocviberpeytvauun dushpmatstaeeeetas omban caves ten eaLac neha: eee 450

(TirLepacn, Contents, and Inpex to Vol. LX.)

[No. 241 of the Quarterly Journal will be published next February. |

[The Editor of the Quarterly Journal is directed to make it known to the Public that the
Authors alone are responsible for the facts and opinions contained in their respective
Papers. |

*,* The Council request that all communications intended for publication by the
Society shall be clearly and legibly written on one side of the paper only, with
proper references, and in all respects in fit condition for being
at once placed in the Printer’s hands. Unless this is done, it will be in
the discretion of the Officers to returnthe communication to the Author for revision.

The Library and Museum at the Apartments of the Society are open every Weekday
from Ten o’clock until Five, except during the fortnight commencing on the
first Monday in September, when the Library is closed for the purpose of
cleaning; the Library is also closed on Saturdays at One p.m. during the

months of August and September. It is open until Eight p.m. on the Days of -

Meeting for the loan of books, and from Hight p.m. until the close of each

Meeting for conversational purposes only.

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