oma CAP Onspeed Soh dint tian thak at aR ose nian Pe th ci file dats Ae ine sy PPS at pT sire A Af Bodie wh Fe op eH NPA AE EIA IO er Wa ee ee ee ore IA BD RD PO oe 6 FaSniie hoo ag Tae M Per Mec heed td Bee athe Gein - th HE teeth 8 Dee Reem h- Gee OF TA Pee 4-8. fea - 6 tart Satie hE Bet tr te Rate weer tee eee Rarrn Fim Me MS tle Be Be ie Ree nt Bod Ereoes te $- hee ee a ee ee ~ Pampa Pact dota tt 4s Pn Soe? ia ed ae now T 1d AIX To, 209 oer) wanop yen? “4TLOONTIGVMS IV NOMLOFS 40 MATA a | 550.EH2 /F 73 Geo/o S / Ape QUARTERLY JOURNAL 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 uiteriora 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. VOLUME THE FORTY- ERRIEN LS Se "ON 1889. oe: Potes fo WY / <2 barionnl WS LONDON : LONGMANS, GREEN, AND CO. PARIS; FRIED. KLINCKSIECK, 11 RUE DE LILLE; F. SAVY, 24 RUE HAUTEFEUILLE. LEIPZIG: T. 0. WEIGEL. SOLD ALSO AT THE APARTMENTS OF THE SOCIETY. MDCCCLXXXIX. List OF THE OFFICERS OF THE GEOLOGICAL SOCIETY OF LONDON. PPA OPIN BrestVent. W. T. Blanford, LL.D., F.R.S. Wice-PrestVents. John Evans, D.C.L., LL.D., F.R.S. Prof. J. W. Judd, F.R.S. Prof. T. McKenny Hughes, M.A., F.R.S. | Prof. J. Prestwich, M.A., D.C.L., F.R.S. Suretaries. W. H. Hudleston, Esq., M.A., F.R.S. | J. E. Marr, Esq., M.A. Foreiqu Secretary, Sir Warington W. Smyth, M.A., F.R.S. Creasurer. Prof. T. Wiltshire, M.A., F.L.S. -COUNGIL, Prof. J. F. Blake, M.A. Major-Gen. C. A. McMahon. W. T. Blanford, LL.D., F.R.S. J. E. Marr, Esq., M.A. Prof. T. G. Bonney, D.Sc., LL.D., F.R.S. E. Tulley Newton, Esq. James Carter, Esq. Prof. J. Prestwich, D.C.L., M.A., F.R.S. John Evans, D.C.L., LL.D., F.R.S. F. W. Rudler, Esq. L. Fletcher, Esq., M.A. F.R.S. Prof. H. G. Seeley, F.R.S. A. Geikie, LL.D., F.R.S. Sir Warington W. Smyth, M.A., F.R.S. Prof. A. H. Green, M.A., F.R.S. W. Topley, Esq., F.R.S. Rev. Edwin Hill, M.A. Rey. G. F. Whidborne, M.A. W. H. Hudleston, Esq., M.A., F.R.S. Prof. T. Wiltshire, M.A., F.L.S. Prof. T. McKenny Hughes, M.A., F.R.S. Rev. H. H. Winwood, M.A. Prof. J. W. Judd, F.R.S. Assistant-Secretary, Clerk, Librarian, and Curator. W. S. Dailas, Esq., F.L.S. Assistants in Office, Library, and Mluseum. Mr. W. Rupert Jones. Mr. Francis E. Brown. TABLE OF CONTENTS. Page Baron, Rev. R. Notes on the Geology of Madagascar. With an Appendix on the Fossils by R. B. Newron, Esq. (Plates BUN NON ae nese cre tye agin c rr stor etegeulter coe open eet ta vpsi ony rac Eee 305 Batuer, F. A., Esy. Zrzgonocrinus, a new Genus of Crinoidea, from the “ Weisser Jura” of Bavaria; with the Description of anew Species, 7. luatus. With an Appendix on sudden Devi- ations from Normal Symmetry in Neocringidea. (Plate VI.).. 149 ——. Note on Marsupttes testudinarius, v. Schlotheim, sp. .... 172 fthewbacals ot, Mugeniacrimidcon: qcri ee niet 359 Bonney, Prof. T. G. Notes on two Traverses of the Crystalline MMe SHON MO pm ANUS) ooh ely in: ane thea aie oh sustohivaluSeee ps iets, s ye 67 Brown, Horace T., Esq. The Permian Rocks of the Leicester- SinmenConl-nelds y@blate: DT.) cys.) Wace gear ee eee 1 Buckman, 8. 8., Esq. On the Cotteswold, Midford, and Yeovil Sands, and the Division between Lias and Oolite ............ 440 . The Descent of Sonninta and Hammatoceras. (Plate OIG 6 esr ee, cae rg ee Aliso shes dvaehe Met aebe tanec ehen are 651 CatLtaway, Dr. CuHarutes. On the Production of Secondary Minerals at Shear-zones in the Crystalline Rocks of the Mal- eet of (Ceplate: OV DS) Se alt eee weynin aitecie anes oaeenhee 475 CANDLER, CHARLES, Hsq. Observations on some undescribed Lacustrine Deposits at Saint Cross, South Elmham, in SUDO arerepaeete teererace Care tee cet rbah nasel sets yonatieve evere’@ve, her «career are 504 CHAMPERNOWNE, A., Esq. (the late). Onthe Ashprington Volcanic DELICS OL SOM lye vom Aiea ss WM wae ele bon ts diesen eeleisiels 369 Coz, G. A. J., Esq., and A. Vaueuan JenniNGS, Esq. The Northern Slopes, of Caden lidris. pet. caerek aa chit Sie el oieitiee on 422 IV TABLE OF CONTENTS. Page Crotut, Dr. James. On prevailing Misconceptions regarding the Evidence which we ought to expect of former Glacial Periods . 220 Donatp, Miss. Descriptions of some new Species of Carboniferous Gasteropoda.: 7 (Plate XX.)i 0 nee... cs... ee 619 Dunuop, Dr. ANDREW. On the Jersey Brick-Clay .............. 118 ETHERIDGE, R., Esq., and Henry Wittert, Esq. On the Den- tition of Lepidotus maximus, Wagner, as illustrated by Speci- mens from the Kimeridge Clay of Shotover Hill, near Oxford. GEA COPAQVE) e cens aici te sta e eas Se nan ow een 356 Gregory, J. W., Esq. Cystechinus crassus, a new Species from the Radiolarian Marls of Barbados, and the Evidence it affords as to the Ave and Origin of those Deposits. ..........2.25= meee 640 Groom, T. T., Esq. On a Tachylyte associated with the Gabbro of Carrock Fell in the Lake District. (Plate XII.) ............ 298 Hateu, Dr. F. H. Notes on the Petrographical Characters of some Rocks collected in Madagascar by the Rev. R. Baron.... 340 Hin, Rey. HE. The Rocks of Alderney and the Casquets ........ 380 Hr, W., Esq., and A. J. Jukes-Browne, Esq. The Occurrence of Colloid Silica in the Lower Chalk of Berkshire and Wilt- Ghitere ten ss hs Sede a sec. nes oe dee Dee 403 Hinpz, Dr.G.J. On Archeocyathus, Billings, and on other Genera, allied to or associated with it, from the Cambrian Strata of North America, Spain, Sardinia, and Scotland. (Plate V.).... 125 JenniInGs, A. VAUGHAN, Hsq., and G. A. J. Cotz, Esq. The Northern Slopes of Cader Idris. ;...........5.. 022 422 JOHNSTONE, ALEX., Esq. On the Action of Pure Water, and of Water saturated with Carbonic Acid Gas, on the Minerals of tmetMica Mamily. ii... ea ee baa dee ben eee 363 Jupp, Prof. J. W. On the Growth of Crystals in Igneous Rocks after their Consolidation. (Plate VIL.)°........)...3.9ee0ee 175 ———. The Tertiary Volcanoes of the Western Isles of Scotland . 187 JUKES-BRrownge, A. J., Esq., and W. Hitt, Esq. The Occurrence of Colloid Silica in the Lower Chalk of Berkshire and Wilt- SUE ccchiateis, adic @ pe ba ab ve baca eee dob dues os ene 40 LampLuGH, G. W., Esq. On the Subdivisions of the Speeton Clay 575 LYDEKEKER, R., Esq. On the Remains and Affinities of five Genera of Mesozoic Reptiles... (Plate 11.) 0.4)... Js een eee 4] TABLE OF CONTENTS. Vv Page LypDEKKER, R. Esq. On Remains of Eocene and Mesozoic Chelonia and 2, Tooth of (?) Ornithopsis. (Plate VIII.) .............. 227 On certain Chelonian Remains from the Wealden and Jig ave ie miter.” See Gadi eet inte vn Naa nee un ge ere 2c, SEA Wee eR Ra 511 Lyons, H. G., Esq. Notes on the Bagshot Beds and their Strati- aren (delene-O9D) lap cateoneoer Sige HHA Nae H mono 633 McManon, Major-Gen. C. A. Notes on the Hornblende-schists and Banded Crystalline Rocks of the Lizard ................ 519 Newton, E. 'I., Esq. Description of a new Species of Clupea (C. vectensis) from Oligocene Strata in the Isle of Wight. GEC IEV) )ip os sotaria catia 2 ele inte Gicapoe ay ance aleedencte che euere eo uMtenen Sere 112 PreEstwicH, Prof. Jos. On the Occurrence of Paleolithic Flint Implements in the Neighbourhood of Ightham, Kent, their Distribution and probable Age. (Plates IX.—XI.) .......... 270 Raisin, Miss C. A. On some Nodular Felstones of the Lleyn .... 247 RopeErts, T., Esq. The Upper Jurassic Clays of Lincolnshire .... 545 Rutiey, FRanK, Esq. On Fulguritesfrom Monte Viso. (PlateIIL.) 60 ——. On Tachylyte from Victoria Park, Whiteinch, near Glasgow. With an Analysis of the Rock by P. Hotiann, Esq. 626 SEELEY, Prof. H.G. Note on the Pelvis of Ormithopsis ........ 391 SHRUBSOLE, W. H., Esq. Notes on the Radiolaria of the London (CIENT ofr ak PDL Chel irr an aia Pura Nae oP RRR 3G Wo 121 Watrorp, E. A., Esq. On some Bryozoa from the Inferior Oolite of Shipton Gorge, Dorset.—Part I. (Plates X VII-XIX.).... 561 WILxetTt, Henry, Ksq., and R. ErHeERIDGE, Esq. On the Dentition of Lepidotus maximus, Wagner, as illustrated by Specimens from the Kimeridge Clay of Shotover Hill, near Oxford. (TEIBWS DOS ER De aa Aran ce acne Pere psi eee ete anima ge maa ah 306 Worth, R. N., Esq. The Elvans and Volcanic Rocks of Dartmoor 398 vi TABLE OF CONTENTS. PROCEEDINGS. Page PATA ENE OTe eeses en Sot what steie Ae aptels Bie ave pie go aa sree eee ojo See iastronmbyell Medallists.) 2.4.3 eee ovis oe ss os oe Pri itistiot iesby Medalists... 61... ees sccenr snes re so: siete Meas Applications of the Barlow-Jameson Fund ..............00. o See BSinenpiAFRCADLE «uci. . oS ace ee od eae d ae owe oes Coe ee eee 24 Aavard oohe Medals Gc. 2... 2.6 20% 0.0 +565 » wees apie 30 Aanmiyersary AGOress i. 2.40.22 ee eet ee ees tee ees 27 Donations to the Library (with Bibliography) .................. 87 ByzE-Laws, notices as to alterations in the...... 6, 7) 785 79, 235 o22085 Gzotocists’ AssoctaTion. Notice of intended Excursion to the Voleanie Regions of Italy .. 0... 00... 1. 5. cee eee 85 Dawson, Sir J. W. Supplementary Note to a paper on the Rocks ot the Atlantic Coast of Canada ......:...:..:- 223 eee 80 Hinpz, Dr. G. J. On some Fossil Siliceous Sponges from the Quebec Group of Little Métis, Canada ..............e000e- 84 KiRog, J. R., Esq. Origin of Movements in the Earth’s Crust.... 83 WHuitTaAKER, W., Iisq. On the results of the Streatham Boring .. 2 LIST OF THE FOSSILS FIGURED AND DESCRIBED IN THIS VOLUME. [In this list, those fossils the names of which are printed in Roman type have been previously described. | Name of Species. Formation. Locality. Page. RHIZOPODA. (Radiolaria.) Eucyrtidium Hammondi .... ee Monosphera toliapica ............4.. London Clay ...|\Sheppey ......... 123 SPONGOMISCUS ASPEP.......eececveceeeees (Foraminifera.) Alveolina oblonga. Pl. xiv. f. 18, \ 19 Assilina spira. Pl. xiv. f. 16......... DOYS Nejeososonnade Madagascar ...... 332 Nummulina biarritzensis. Pl. xiv. | USE RE Ee arsisca en csrocesvacdee sess. cs I AMORPHOZOA. Archeoscyphia minganensis. Pv. ee WAL De cieiicisicin taicislctee ehs's eetecincleiaaie Cambrian ...... N. America ...... 143 Nipterella paradoxica. Pl. v. f. 15 144 C@LENTERATA. ( Actinozoa.) Archzocyathus ichnuse. PI. v. f. 3 | (|Sardinia ......... 132 profundus. Pl. v. f.1-5...... i Canada ieee cna. 131 Ethmophyllum Whitneyi. PI. v. f. 7 . N. America ...... 133 Protopharetra, sp. Pl. v. f. 11...... Cambrian...... : Sanginiauecseses 135 Spirocyathus atlanticus. PI. v. f. | | eT cacy Snr }| | [Labrador......... | 136 Vill FOSSILS FIGURED AND DESCRIBED. Name of Species. | Formation. | Localit . ECHINODERMATA. Cystechinus crassus ...........++<+.+- (Pliocene ?......... ‘Barbados ....... Eugeniacrinus caryophyllatus ...... | (Bavaria ....... Pep ND). Soinoce saw inceceencie secs sins Stomechinus bigranularis ? Pl. xiv. Jurassic Trigonocrinus liratus. P|. vi. f. 1-7 PoLYZOA. Bisidmonea tetragona, var. ovalis. \ ls San By ee Entalophora magnipora. PI. xix. f. MEU ae eee ea eio cis san csietgacene mairipotan PL xix. £10. 20.6. PV Are AROMA... ccecee- as ——- richmondiensis .................. —— subgracilis, var. corrugata. 1 LL SUT gel I ae ee Idmonea claviformis. Pl. xix. f. 1, 2 stomatoporoides. P1. xix. f. 5, 6 triquetra, var. Parkinsoni. Pl. TULL, a Se ee es ee ——, var. Y-formis. PI. xix. 12, ly SRA CECOn Aen amar ce een er Proboscina incrustans. Pl. xvii. f. } Oolite ............ Dorsetshire .... Be a eae ake ho wn cama spatiosa. P).xvii.f. 1-3 ...... , var. brevis. Pl. xviii. f. , var. brevior. Pl. xviii. | Stomatopora dichotoma............... —-— dichotomoides .................. tbs Oe oo aa ae porrecta. Pl. xviii. f.7,8 ... spuiias, Tl xviii. £.16.5.002..2 LL Te ak, A a Ae Aa Sener MoLuusca. (Lamellibranchiata.) Alectryonia ungulata. Pl. xiv. f. Me tec ce nica ssa cae ctw arises Cretaceous ...... Madagascar .... Astarte(?) Baroni. Pl. xiv. f. 9- oF aah eee ee mee eee sees eerer Sete sseeeseetee Ae Madagascar uae 1B Ces he Sae ce stenne ave erent ie Cap rer ‘Madagascar .... [Bavaria <2csee TT aS mts ence tN A ep ee Page. 641 362 338 161 333 336 336 FOSSILS FIGURED AND DESCRIBED. 1x Name of Species. Formation. EMou.usca (continued). ( Gasteropoda.) Murchisonia (Goniostropha) turri- ) Bilatase Ply xx. fo 0" easei coe. Or ( ) , var. scotica. Pl. POMBO tess teicsineisie sess ciadnccne esas — (Stegocelia) es oe - ; x. f. 9-13 Nerita Buvignieri. Carboniferous 4 | \ eee eee ses POSES ees eee eteees Pl. xiv. f.5 ... {Jurassic Locality. Yorkshire Ayrshire .... Ayrshire Bitalneeeseseeee seeoars ste Madagascar...... | F Orthonema pygmeum. Pl. xx. f.| 7 24 noosdepenngopnonsereneeasseancaanse: ‘Carboniferous ...|Ayrshire ......... ——- ? Youngianum. PI. xx. f.3, 4. ( Cephalopoda.) Amalthens margaritatus. Pl. xxii. ARBOR DO! dieys Sviacnirsteleac Wlewinties Absit IGIIENS ede qcacoasaceee England ......... Belemnites polygonalis. Pl. xiv. f. oe cclenc(aniain Sele rae ea dee Saleen iale’s Cretaceous ...... Madagascar...... Hammatoceras amplectens............ } door) Plixxa to 17, 18)... | Sonninia acanthodes. P\. xxii. f. 6, }|Lias............... LSTA ENT, Socoseaoe READ ace aaierc's vais eseleneiaiasion «vac | SUGUIGONOUG 3.0 eqcuncaet eins) + Stephanoceras Herveyi. Pl. xiv. f. RR ce scons nak Salta sinlo ate JuTassiy esas: oe: Madagascar...... Witchellia leviuscula. Pl. xxii. f. CAS ois pes Se a ae ene i Aaa LIES erscoscoaccnace England se.cseee VERTEBRATA. (Pisces. ) Ciupeaveciensis. “PY. iV... .6.00+2-- Oligocene .... -jisle of vee 3c8 Lepidotus maximus. Pl. xv. ...... ‘Kimeridge ...... England .. (Reptilia.) Argillochelys cuneiceps ............4.- London Clay ...;/Sheppey ......... Camptosaurus Leedsi ............000005 Oxford Clay ...|/Peterborough ... Ciielane JESSONG cies n dee canst teaser Cretaceous ...... Cambridge ...... GWlvelonrany 3255 25 coe setae aco «220 Shaaiac Wieald enteecssce-: DLISSO Meee ae Dacochelys Delabechei ........0...00. London Clay ...|Sheppey ......... Lytoloma cantabrigiense ............ Cretaceous ...... Cambridge ...... Wes alosaiimuse Spe os 4 nace saecise ie Weald Isle of Wight ... Ormichopsis? Tooth. ...2. .ca-sedeecses crete ile IGEN Gia ine yesecnietee Peloneustes philarchus. eM ween. Oxford Clay...... Bedtoxd seer eee VOL. XLY. 622 622 623 624 339 620 620 113 356 x FOSSILS FIGURED AND DESCRIBED. Name of Species. Formation. Locality. Page. VERTEBRATA (continued). ( Reptilia, continued.) Plesiochelys Brodie? J..s0.0-0:-21---+- r mee 238. DOILENSIS Fs wrgestnge a ok sence san \ ee islevol Waa | “2ae Pleurosternum Bullocki............... Purbeck "2. 2%s2.-- ‘Dorsetshire ...... _ o16 Rhinochelys brachyrhina. P}. viii. | (\ Le eg tees aeReN EN lo tiavs Sales | “Zatl -—— cantabrigiensis. P. viii. f. 2. | | | 230 dlegans. blew. £.°5. <.....26 - Ce * 2 I | je Wecini SPE. 6 |... (Cretaceous, -..._ Cambrai. macrorhina. Pl. vii.f.7 ... | 231 pulchriceps. PI. viii. f. 1 | 230 Syngonosaurus macrocercus ......... ) \|. 45 EXPLANATION OF THE PLATES. PLATE Paar Szctron at SwaDLiIncoTE In Marcu 1888, to illustrate Mr. H. I. T. Brown’s paper on the Permian Rocks of the Leicester- plore: Coaleticl dive urs atcce sec canes rete Wg thin cae nda eee 1 PELONEUSTES PHILARCHUS, MANDIBLE AND VERTEBRZ, to il illustrate Mr. R. Lydekker’ S paper on Five Canon of IMIS OZ OUCH EVE LUNs s caa-ntr cen ect corona Raion caine eae a aero 41 Ir Funeurites rrom Monte Viso, to illustrate Mr. T. Rutley’s : Oey CSO a) 12 Me he GUI O XC noe paacnua ogBemtbeonne Socoeadacamonbecbsouont 60 CLUPEA VECTENSIS, to illustrate Mr. EH. T. Newton’s paper on IV tat S Pe Ctes ese /A. cus ak dan aculcn cap lstsen cece e ee eee aoe eee 112 Vv CaMBRIAN ARCHAOCYATHIN[E AND SponcGeEs, to illustrate Dr. G. J. Hinde’s paper on Archeocyathus and allied Genera. 125 TRIGONOCRINUS LIRATUS ETC., to illustrate Mr. F. A. Bather’s I. : Mi PAPE OM L7G OMOCTUNUS santo ncn eemne teen eee eee eee eee 149 poriTE-ANDESITE, Isuzu or Mutu, to illustrate Prof. J. W. | SEconDARY OUTGROWTHS TO F'ELSPAR-CRYSTALS IN LABRA- VII Judd’s paper on the growth of Crystals in Igneous Rocks 175 CraniA oF Rurnocuetys, to illustrate Mr. R. Lydekker’s aut { paper on Hocene and Mesozoic Chelonia ............4.:60 00 227 IX. (Mar or toe Drirt-peps ArounD IcuTHAM AND Furnt Inpre- X. MENTS FROM THEM, to illustrate Prof. J. Prestwich’s paper PRO Gon tatisubyecticcueanic (cues smectic cstee. case teacher cnecere 270 XIL. TACHYLYTE FROM CaARRocKk Fett, to illustrate Mr. T. T. Groomis;paperony tiatssulbject a su. ice- cst ee seee eee anaes 298 GeEoLocgicAL Map oF THE NorTHERN Part or MADAGASCAK, XIII. to illustrate Rev. R. Baron’s paper on the eee of that Mislead Bere vn stout strc ec ease at cence ae eater dete eee ee aN cite RACs . 305 XIV. Fossius ¥rroM Mabacascar, to illustrate Mr. E. T. Newton’s Jhroporsvacaline WO) IMU, Ter uONVS) JORY OE brceocgn oraddnecbebousanaedcbooc. 331 Xii EXPLANATION OF THE PLATES. PLATE PAGE XV DentiTION oF LEPIDOTUS MAXIMUS, to illustrate Messrs. Etheridge and Willett’s paper on that subject ............... 306 J Sections oF Rocks From THE Matvern Cunatn, to illustrate XVI. Dr. C. Callaway’s paper on Secondary Minerals at Shear- ZONES In THOSE TOCKS fo. 522~..cosecr senses recess elncsaeee eee eae 475 ea Inrerior Oouite Bryozoa From Surpton Gores, Dorszt, to : illustrate Mr. E. A. Walford’s paper on those fossils ...... 561 pap XIX. xx ‘ CARBONIFEROUS GAsTEROPODA, to illustrate Miss Donald’s ; | paper ON some New Species ......02.-- --00--secenrennsoneaswanras 619 XXI Sxrercu Mar or tHE COUNTRY BETWEEN ALDERSHOT AND ASCOT, 3 | to illustrate Mr. H. G. Lyons’s paper on the Bagshot Beds 633 SuTURES AND INNER WHORLS oF AMMONITES, to illustrate Mr. XXII. S. S. Buckman’s paper on the descent of Sonninia and PLAMMOLOCEVAS cen ereslden cunwans easce ones ase cb onbeeeeeeE eee 651 ERRATA ET CORRIGENDA. Proc., page 48, line 12 from bottom, after ‘ composed ” znsert “ of.” Page 182, line 6, for “anges” read “ changes.” Page 220, last line, for “Rr” read “a.” Page 229, line 21, for “ skulls” read “ shells.” Page 238, fig. 4, twelve marginals shown ; there should be only eleven on each side. Page 310, line 24 from bottom, after “ that” read “the.” Page 546, in index to Map, symbols of Kimeridge Clay and Corallian transposed, Page 571, line 10 from bottom, for “ R1cHMoNDIENSE” read ‘‘ RICHMONDIENSIS. THE QUARTERLY JOURNAL OF THE GEOLOGICAL SOCIETY OF LONDON, Vout. XLV. 1. The Permian Rooxs of the LetcesteRSHIRE CoAL-FIELD, By Horace T. Brown, Hsq., F.G.8., F.I.C. (Read Nov. 7, 1888.) [Puarte I.] ConTENTs. Page PO SerauieTa PHICA GP Aes. tesa crest oeceae satedonoce aeaels 1 (2) Lithological Characters of the Beds .................. 21 (3) The Rock-fragments of the Breccias, with their pe- PrLOlopical ExamInatlOMs, .... ...20<5.neaeacdsaeeeeetss 22 (4) The origin of the brecciated fragments ............... 27 (5) Correlation of the Beds with the Permians of sur- rounding districts, and a consideration of the physical conditions attending their deposition ... 35 (6) Appendix. The igneous rocks of the Market BOSwOLt DOLINGEcs.5c.0s2.-0c 22 soccssteoe are ov (1} SrraTIGRAPHICAL. Tas exposed Carboniferous strata of the Leicestershire Coal-field are bounded on their western edge by a narrow strip of coarse current- bedded sandstones and conglomerates, which form the base of the Trias in this part of the country, and which are doubtless homo- taxial with the typical Bunter Conglomerate of South Staffordshire, Shropshire, and Cheshire. These sandstones and conglomerates are about 120 feet in thickness on the extreme margin of the Coal- field, but when traced eastward for two or three miles, by the aid of several small outliers, they are found to thin out rapidly, and, Q.J.G.8. No. 177. B 2 MR. H. T. BROWN ON THE PERMIAN east of a line drawn north and south through Ingleby and Measham,, are conformably overlapped by the Lower Keuper *. The Trias, throughout the greater part of the area, rests upon the truncated edges of Carboniferous rocks, either upon Coal-measures,. or, in the northern part of the district, upon Millstone Grit or even Yoredale Shales; there are, however, found here and there, intercalated between the Bunter and the Carboniferous, some thin beds of purple marls, breccias, and sandstones, seldom exceeding in agetegate thickness 30 or 40 feet, but differing remarkably, in lithological characters, from both the overlying and the underlying rocks. My attention was first seriously directed to these rocks during a. re-survey, on the six-inch scale, of a tract of country lying imme- diately to the east of Burton-on-Trent, and the results obtained induced me to make a careful examination of the beds throughout the Coal-field; for, although described and mapped as Permian by the Survey geologists, doubts have been from time to time expressed by various observers as to the true stratigraphical relations of these somewhat obscure rocks. About the true relation of this brecciated series to the Carboniferous there cannot be the slightest doubt ; for when its various members- are traced for a little distance along their line of strike they are found to repose successively on Carboniferous strata belonging to very different horizons. This well-marked unconformity has been referred to by Professor Hull in his Survey Memoir, and, so far as I know, only one geologist, the late Mr. W. Molyneux, F.G.S., has attempted to link the brecciated series with the Carboniferous System. In his ‘ Burton on Trent, its History and its Waters,’ Mr. Moly- neux regards these rocks as Upper Coal-measures, and correlates them with the breccias and clays of the upper division of the Coal- measures of North and certain parts of South Staffordshire. He bases. this opinion, in the first place, upon a fancied lithological resemblance between the beds of the two districts, and, secondly, upon the supposed fact that the breccias of the Leicestershire Coal-field do not appear “in any section beneath the highest known workable seams of coal of the Ashby Coal-field” (op. cit. p. 153). This state- ment certainly does not bear close examination; for besides being lithologically very dissimilar to the Upper Coal-measure breccias of the North-Staffordshire Coal-field, which are well shown in the neighbourhood of Stoke-on-Trent, these brecciated rocks of the Lei- * The disappearance of the Bunter eastwards was first noticed by Prof. Hull, and is mentioned at p. 61 of the Memoir on the Geology of the Leicestershire Coal-field. As we have not the slightest evidence of any unconformity between the Bunter and the Keuper in this part of the country, the thinning-out of the former, and its complete overlap by the Lower Keuper, can only be satis- factorily explained by assuming the proximity of an old coast-line of early Triassic times, or, if we accept the views of Prof. Bonney as to the origin of the Bunter, of a portion of the left bank of that great northern river which brought down, from beyond the Scottish border, the rounded pebbles of the Middle Bunter. ROCKS OF THE LEICESTERSHIRE COAL-FIELD. 3 cestershire Coal-field rest with the most striking unconformity upon the true Coal-measures. In proof of this, I will mention the following facts :—At Brizlincote the breccias rest upon the “ Well” coal, whilst, when followed along their line of strike for a distance of only 2000 yards further south, they are found, at the Newhall Park Col- liery, in contact with the Nether Main Coal, having consequently overlapped the Coal-measures in this short distance through a ver- tical thickness of 450 feet. Again, only 27 miles east of Newhall Park, at Swadlincote, the breccias immediately overlie almost the highest known coals of the district, occurring at a horizon 861 feet above the Main Coal. So that within a very small areathe brecciated series occurs in contact with Coal-measures separated from each other by a vertical distance of over 1300 feet, almost the entire thickness of the productive portion of the Coal-field. If any further proof of unconformity were necessary, it is afforded by the detailed sections to be referred to later on, and by the fact that the great Boothorpe fault, which traverses the Coal-field ina N.N.W. and S.S.E. direc- tion, whilst dislocating the Coal-measures near Woodville to the extent of at least 1000 feet, affects the overlying brecciated series at the most 20 or 30 feet. There cannot, therefore, be the slightest doubt that the view expressed by Professor Hull (Survey Memoir, p. 57) that these strata “‘do not form part of the coal-formation, but are of more recent origin,” is the correct one. On the other hand their relation to the overlying Bunter Con- glomerates is not at first sight quite clear. It has been noted that the Bunter Conglomerates do not occur east of a line drawn from Measham to Ingleby; the brecciated series, however, does occur in one or two spots east of this line, and in these cases is succeeded upwards by the Lower Keuper Sandstone. From the fact of this eastward overlap by higher beds of the Trias, Prof. Hull concludes (Survey Memoir, p. 58) that the breccias do not belong to this latter formation, and doubtfully refers them to the Permian. This evidence is, however, no absolute proof in itself of the ex- istence of a stratigraphical break, amounting to an unconformity, between the brecciated series and the Trias; for we must bear in mind that we are in close proximity to an old shore-line, which we know gradually receded eastward during subsidence of the old Carboniferous land: hence it seemed to me by no means improbable that the breccias might, after all, belong to the base of the Trias, and represent marginal deposits which swept up the sides of the gradually submerged land, bearing the same relation to the several divisions of the Trias in this part of the country as the Dolomitic Conglom- erate of Gloucestershire and the neighbourhood of the Mendips bears to that of the south-west of England *. This appeared to me to be an alternative and by no means impro- bable explanation of the facts as known until recently; but I have, within the last few years, been able to accumulate a mass of evidence * The Keuper breccias at Thringstone, on the borders of Charnwood Forest, are undoubtedly marginal deposits of this kind. They are composed of angular fragments derived from the adjacent Forest-rocks. BQ 4 MR. H. T. BROWN ON THE PERMIAN which leaves no doubt that Professor Hull’s surmise as to the Per- mian age of at least some of these beds is quite correct. Whilst engaged in mapping the Coal-measures and overlying rocks on the north-western boundary of the Coal-field between Bretby and Gresley, I obtained many indications of the brecciated series cropping out at the base of the Trias. These small patches were, for the most part, discovered by the constant use of a small hand- borer, consisting of a light jointed steel rod, armed at the end with an auger about 2 inch in diameter. The surface appearances very often afford no indications of the existence of the breccias and their associated rocks ; but by adopting this method, which is easily and rapidly carried out in the field if one has a little assistance, I have been able to discover the existence of the rocks in question in many places hitherto unsuspected, and to delineate their boundaries with absolute accuracy on a large scale map. In tracing the beds by these means from north to south, I have found the intercalation of the breccias between the Trias and the Carboniferous so extremely uncertain, and their more or less complete overlap by the Bunter so frequent and abrupt, that the facts are not capable of being satisfactorily explained by anything short of an unconformity between the brecciated series and the Bunter. Better proof of this unconformity is afforded by certain sections which areto be seen on the western boundary of the visible coal- field, at the Newhall Park Colliery, about one mile north of Gresley station *. Here, in a railway-cutting about 150 yards in length, running in a direction approximately E.S.E. and W.N.W., the Nether Main Coal comes into view near the colliery-shaft, with an apparent easterly dip of 13°. The coal-seam does not quite reach the surface, but is cut off by a fault with a downthrow of 36 feet to the west, thus causing a repetition of the coal outcrop about 70 yards further west. At this point the Nether Coal is covered with a few feet of brightly coloured and strongly variegated red, yellow, and white clays, rapidly giving place, further west, to a bed of dull red breccia. This breccia consists of large and small angular and subangular frag- ments of rock, imbedded in a red calcareous matrix. In places it is consolidated, but near the surface forms a loose rubbly mass showing little or no signs of stratification. The following sketch (fig. 1) indicates the position of the beds on the south side of the cutting. On the opposite side of the railway the breccias are to be seen resting, apparently horizontally, upon an eroded surface of light-coloured Coal-measure clay which appears to dip 18° E.S.E. The line of junction of the two series of beds is marked by a thin band of coal-smut, the triturated remains of a portion of the Nether Coal which cropped out at this spot on the old Permian beach. In the underground workings of the colliery the breccias were * The beds here described do not appear in our one-inch Survey map. ROCKS OF THE LEICESTERSHIRE COAL-FIELD. 5. struck, whilst driving a heading, at a depth of 70 ft. from the sur- face, and about 700 ft. south-west from the mouth of the shaft. This is as nearly as possible the position they ought to occupy from the surface indications, their true dip being 10° due 8. In the pit-section the breccias exactly resemble those of the sur- face except in colour, the matrix of the former being bluish-grey variegated with a little red, whilst that of the latter is a dull red throughout. This is merely a question of weathering, and the difference is ex- tremely well shown in the Swadlincote section pre- sently to bedescribed. The iron, in the freshly cut and unweathered surfaces, is mainly in the ferrous state and becomes oxidized on exposure. Although the Bunter Con- glomerates are seen to over- lie the breccias of Newhall Park afew yards south of the railway-section, the actual line of junction has not been laid bare. The Bunter has a dip of 7° to 10°S. 63° W. ; we consequently have the three series of rocks, in sections within a few yards of each other, showing the following angles and direc- tions of dip, sufficiently in- dicating a double unconfor- mity :— Bunter Conglomerate 7° to 10° S. 63° W., (Permian) Breccias 10° 8. Coal-measures 15° S. 26° EH. In the neighbourhood of Swadlincote and Woodville two sections have recently “SOINSBVIUL-[BOD *‘TeoD 19q99 Ne “qUIS-[BOD ‘s{v[Q oANSvaUI-[VOg aC BCE “kvTO poyedorse A_ — ee ee ‘SHOOUY NVINUT JOOF QT OTVOS [VOIYIOA © POUT T 2 =) NG 400} FG o[BOs [e}WOZ110 77) "hiaypoyn yn yoymayy ‘hnaymay fo apis yynoy uo uon»g9—'T *B1q — (qu | been opened out which must completely set at rest any doubts which may still be entertained as to the true stratigraphical position of the brecciated series *. * These breccias, which are known to the workmen as “Grout,” are not indicated on our one-inch Survey maps of the district. 6 MR. H. T. BROWN ON THE PERMIAN The first which I shall describe occurs at the Boothorpe Sanitary Pipe Works at Woodville, 500 yards 8.W. of the Waterworks tower. The details of the section are as follows (see fig. 2) :— Fig. 2.—Section at Boothorpe Clay Works, Woodville. ft. in. ft. in. Beates eae. Sandstone and Conglomerate, with a hk Aaa few elay-partings' (¢)i.....-.2e-sfasqosse eee ee ( Breccia—Fragments of quartzite, fine grit, | slate, &c., in a bluish-grey calcareous [ -amvatiin’ (6) Ai. tests esSeet ee ene ee eee 0 Oto3 0 Permian, .....0.0: | Grey Marl with occasional seams of very |. ‘small pebblés:..<... ssscumeecnaee atest eee eeee 1° © | Red and variegated Marls (6')...........,.....- 3 0 Coal-measures... Highly disturbed purple and grey mottled Clay (@)\ 0.2.3) sstaceeeat acct eee cae ean 3 0 The Coal-measure clays at the base of this section are highly disturbed and exhibit a very strongly marked slickensided appear- ance, doubtless produced by the forces which brought about the great Boothorpe fault, which passes within 100 yards of this exposure and throws the Coal-measures to the extent of at least 1000 ft. The red and grey marls and breccias, which follow in upward order, rest upon an uneven floor of Coal-measure clays, and dip * 5°8., whilst the evenly bedded Bunter Sandstones and Conglomerates overlying them have a dip of only 4°S. In consequence of this the Bunter, as the northern end of the section is reached, gradually oversteps the truncated edges of the overlying brecciated series until it rests directly on the Coal-measures. A careful examination of the exposure renders it perfectly certain that the brecciated series must have been subjected to very consider- A short distance south of this section the beds have a regular dip to the E. ROCKS OF THE LEICESTERSHIRE COAL-FIELD. a able denudation prior to the deposition of the Bunter, and that the phenomena cannot be explained by contemporaneous erosion. This section, in fact, exhibits in a very beautiful manner a double uncon- formity, and clearly proves that we may without doubt refer the series of strata to which the Breccias belong to the Permian; for they are not stratigraphically connected either with the Carboniferous or with the Trias. Swadlincote (fig. 3 and Pl. I.).—The stratigraphical break between the Permians of the Leicestershire Coal-field and the Trias is still more strikingly evidenced by an exposure in an open-working at Swadlincote, about 1 mile north-west of the section last described. The pit has been excavated for the purpose of procuring fire-clay, and is 750 yards south-east of Swadlincote Station. This is the exposure referred to by Mr. W.S. Gresley, F.G.S., in his paper “ On the Occurrence of Fossiliferous Hematite Nodules in the Permian Breccia of Leicestershire ”’ (‘ Midland Naturalist,’ vol. ix. 1886). The ridge of ground on the side of which the pit is situated is correctly shown on the one-inch Survey maps as an outlier of Bunter Conglomerate. The magnificent section is from 70 to 80 ft. in height, and shows about 8 ft. of horizontally bedded Bunter Conglomerates of the usual type of the district, resting upon about 26 ft. of Permian beds made up of sandstones, breccias, and marls. The Permians, together with the underlying Coal-measure clays and their associated coal-seams, dip into the side of the hill at an angle of 23°, in a direction N.50° E., so that the unconformity between the Trias and the underlying beds is most striking. That there is any great break between the Coal-measures and the Permian in this section is not very apparent at first sight, as both seem to dip at the same angle of 23°; but since the section is almost along the line of strike it is possible that there may be a little discordance of dip which is not evident in the present state of the excavation. The unconformity in this case is, however, indicated clearly by the abrupt change in the lithological characters of the beds and by the occurrence at the line of junction of an eroded and impersistent bed of hard, fine-grained, Coal-measure sandstone (“cank”). The following are details of the section as taken in July, 1886; but since that time the face of the excavation has been carried some yards further into the hill, thus exposing a considerable thickness of Lower Keuper Sandstones and Marls above the Bunter Conglomerate, besides showing a considerably greater thickness of Permian and rendering still more evident the distinct break between this series of rocks and the Coal-measures. 8 MR. H. T. BROWN ON THE PERMIAN Fig. 3.—Section at Swadlincote*. Lower Keuper .. Es) ee 6 ae Z| a‘ Permian ......... % a € at. Z EA Coal-measures . S LBAZEAAAAZAZX@ = a, Breccias. b. Buff-coloured Sandstones. c. Red and white marls. ft. in. ft. in. Bumter......<2<00% Soil and disturbed ground. ..............0.2006+ 4 0 ft. in. ft. in. 4 Pebbly Conglomerate with a few thin beds 5 Oto8 0 of eoarse'’sandstone, 222i... cote. 5 0to8 0 ( Sandstone, soft and light buff-colour ......... 4 0to0 O Red and Grey Clay, becoming sandy upwards. 1 6 Sandstone, grey, tinged with red; evenly bed- | ded, fissile and beautifully rippleemarked. 3 3 Sheht clay parting “2. ...3:. 6c 0 3 Breccia; divided in middle by 13 in. clay dnd sand parting!) 2.05. .ccsc-c