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Summary of the history of geological research among the rocks of the Birmingham District
SUMMARY OF THE HISTORY OF GEOLOGICAL RESEARCH AMONG THE ROCKS OF THE BIRMINGHAM DISTRICT. This paper has been drawn up mainly for the use of those geologists who took part in the Long Excursion of the Geologists' Association in 1898. Consequently, while it includes a general sketch of th e geology of the district as a whole, only those geological formations visited by the members during the Excursion have been treated of at length. But since those formations of which least is known-where discovery is still in progress, and where opinion for the time being is necessarily divided-are of the greatest interest to outsiders, these have been noticed in fuller detail, while the better known formations have been but briefly touched upon. The history of Geological Discovery in the Birmingham District is intimately bound up with the history of British Geology in general, and dates back to the time of Hutton and Playfair. Playfair, in his" Illustrations of the H uttonian Theory " (1802), noticed the Pebble Beds and pebbly drift of the Midlands, and referred both to the stratified Lickey Quartzite as their probable source of origin. William Smith, between 1780 and 1815, first distinguished the three prominent rock 'systems of the district-the Carboniferous, the New Red Sandstone, and th e Jurassic (Lias and Oolite), and defined and mapped some of the larger divisions of the last named groups. Professor Buckland, in 1821, examined and described the Quartz rocks of the Lickeys, a nd noted the igneous rocks of Barnt Green. He observed th e Transition (Silurian) rocks 011 the flanks of the hills, as well as the associated Carboniferous beds, paralleled the Lickey Quartzite with the Quartzite of the Wrekin and Caradoc, and concluded that the Lower Lickey Hills "existed as a group of Palseozoic Islands surrounded by the New Red sea." He even asserted that " the true place of this Lickey Quartz rock appears to be at the lower extremity of those deposits known as the Greywacke. " These rocks of the Lickey, and also those of the Nuneaton district, were next described by the Rev. James Yat es in 1829, and both were correctly paralleled by him with the Wrekin and Caradoc series of Central Shropshire. Murchison spent much time in the District between 1825 and 1835, and devoted an important part of his great work on the "Silurian System " to a description of the Midland rock s; his account of the Silurian strata of the Dudley and Malvern areas is classical. He gave a full account of the New Red of the Midland region, and carefully distinguished the Midland Permian strata, which Buckland 31 AUGUST, 1898.]
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had confounded' with the Old Red Sandstone, as the lower half of the New Red Sandstone, and paralleled the group as a whole with the Rothliegende of Germany. The Permian" trappoid breccia," however, he believed to mark the outcrop of an igneous rock, and he claimed the Lickey Quartzite as being of Silurian age (Llandovery), believing it to graduate upwards into the Llandovery fossiliferous sandstone of Rubery. He suggested that the Lower Lickey Hills lay along an' old volcanic fissure (marked by an igneous rock occurring at Kendal End, near Barnt Green) by which the Silurian beds had been changed into quartzite. A second period in the history of geological research in the Birmingham District is marked by the work of the National Geological Survey. The mapping of the District by the officers of the Survey was carried out between 1840 and 186o, mainly by Sir A. Ramsay, Prof. Jukes, Prof. Hull, Mr. Howell, Prof. Phillips, Sir A. R. Selwyn, and Mr. Aveline. Prof. Phillips mapped the district of the Malvern and Abberley Hills, and described the rocks in the second volume of the Memoirs of the Geological Survey. Jukes (who was a native of Harborne, near Birmingham), mapped the South Staffordshire Coalfield, and his memoir on "The Geology of the South Staffordshire Coalfield," is a model of what such a work should he; but even the second edition has long been out of print. Hull mapped the Leicestershire Coalfield, and (mainly within the limits of the Birmingham District) fixed the boundary between the Permian and Triassic systems, distinguished and named the accepted divisions of the Midland Permian, Bunter and Keuper formations, and ascertained their sequence in the district. His Memoir (1869), " On the Triassic and Permian Rocks ., of the Midland Counties of England, is still the standard work upon the subject. Howell mapped the East Warwickshire Coalfield and the surrounding country, embodying his results in his well-known" Geology of the Warwickshire Coalfield." Ramsay gave a general superintendence to the whole work, and studied personally the more difficult points and problems. The final result of the work of the Surveyors was to place before the public a complete series of geological maps covering the whole area of the Birmingham district, coloured so as to represent not only the various geological systems recognised, but also their main subdivisions. These maps were upon the scale of one inch to the mile-the only scale then published-and when we have regard to the smallness of this scale, and the minute character of the geological work, the general accuracy of the geological lines inserted upon them is beyond all praise. They were illustrated by many coloured longitudinal sections acrossthe more typical parts of the country (upon a scale of six inches to the mile), and by vertical sections
GEOLOGY OF THE BIRMINGHAM DISTRICT.
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(upon a scale of forty feet to the inch) of the strata pierced in the shafts of the chief collieries of the Midlands. During the progress of the Survey many fresh discoveries were made and many novel views brought forward. The Surveyors proved beyond doubt that the "trappoid breccia" of the Permian was not the disintegrated surface of an igneous mass, but formed a constituent stratum of the Permian system. To explain the position and probable mode of formation of this breccia, Ramsay wrote his famous paper upon the subject, in which he advanced the theory of its glacial origin. and suggested its derivation from the distant Longmynd, Caradoc and Wrekin areas of Shropshire. Jukes, on the other hand, was led by his field work to the opposite opinion, namely, that the breccia was probably derived from ancient rocks in the immediate neighbourhood, which were exposed to denudation in the Midland areas during Permian time, but were afterwards buried from sight by later deposits. Again, while Buckland had published his opinion that the Lower Lickey Hills had existed as islands in the New Red Sandstone sea, and were enveloped unconformably in the surrounding mass of New Red -sediments, Ramsay held that the field work showed that they were bounded by faults on both sides, along which they must have been relatively elevated since New Red times. Further, as no stratigraphical break was discoverable at Nuneaton between the Hartshill Quartzite with its associated rocks and the overlying Coal Measures, Ramsay felt himself unable to accept the views of his predecessors that they were of the age of the Wrekin and Lickey Quartzites, and they were consequently coloured by him on the Survey Maps as Millstone Grit and Lower Coal Measures. The period (1856- 1 88 1) which followed the publication of the Survey Maps and Memoirs, was marked by the brilliant petrographical researches of the late Mr. Samuel Allport (a native of the district), and by the discoveries and conclusions of those geologists who were busied in developing the Archrean rocks which existed either within the boundaries of the district or in areas more or less related. Allport's description of the Doterites of the South Staffordshire Coalfield, the Diorites of the Nuneaton district, and of the Rhyolitic lavas and agglomerates of the Wrekin and Wrockwardine areas, are classic in the history of British petrology. Dr. Holl'saccount of the so-called metamorphic gneissose and schistose rocks of the Malvern Hills (published in 1865), in which the original suggestion was made that these rocks were probably of Laurentian or Archsean age, was the pioneer of that host of geological papers dealing with the Archrean and preCambrian rocks of Britain which dominated our geological literature for the next twenty years. In 1876 Dr. Hicks distinguished and named the Pebidian rocks below the Cambrian of St. David's. In 1877-8 Professor Bonney and the Rev. E. Hill published the sequence of the Charnwood Forest rocks, and in 1878 threw out
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the sugges tion that the y might be of Pebidian age. During these years, also, Dr. Callaway published acco unts of his original and far-reac hing researches in Central Shro ps hire. He first an nounced (187 7) his discovery of a typic al T re madoc fauna in the Shineton Shales, and showed ( 1878) that the stratigraphical evidences led to the conclusion that th e Wre kin Quartzite (in place of being of Bala age, as previously supposed) was either of Cam brian age, or more probably, Archsean, Discovering th at the Wrekin "lavas and pyroclasti c rocks (aft erwards named by him Uriconian'j underlay thi s Quartzite unc onformably, he drew (1879) the con clu sion that they mu st be of pre-Cambrian (o r Archrean) age, a con clusion which is now almost universally accepted. In 1880 he sho wed that rock s similar to those of the Wrekin occurred in th e Malvern range near H erefordshire Bea con , overlying the gneissose rocks unconformably. Fo r th is underl ying gneis sose series he had already suggested th e title of .M alvernian ; and a few years lat er he employed the title of Longmyndian, as a designation for th e un alt ered pre-Cambrian rocks of the Longmynd. The final period, nam ely, from th e commencement of 1882 down to the present time, has be en marked mainly by discoveries in th e stratigraphy of the various geological formations of the Birmingham D istr ict and by research es among th e Midland Glacial deposits. We may first tr eat of the Cambrian and preCambrian rocks. Early in J 882 the un conformity betwee n the Llandovery Sandstone of Rubery and the Lickey Q uartzite was d iscovered in the field indep enden tly by Mr. F. T . S. H oughton and by Pr ofessor Lapworth. During th e same year Lapworth detected the bedded pyroclastic basement rocks of Barnt Green in the area in wh ich Murchison had recognised intrusive igneous rock s, bu t which had be en mapped as an outcrop of the Permian breccia. A short time afterwards Lapw orth and Mr. W. J. Harrison ascertained th e bedded nature of the suppose d intrusive igneous rocks of Caldecote near Nuneaton , Lapworth next discovered the Cambr ian fossils of the Stockingford Shales,and work ed out the sequ ence of the beds ; and Harrison discovered the Cambrian inlier of Dost Hill. These results led to a revision of the Nuneaton area by the Geological Survey . In 1885 Mr. A. Strahan re-mapped the area, and pro ved, for the first time, the unconformity between the Cambrian and Ca rboniferous. The officers of the Survey made a collection of the Cambrian fossils of the district, and in the next year (1886) a revised ed ition of Sheet No. 63 S.W. was issued to the public, in which th e rocks were coloured as Lower S iluria n (Cambrian), and assigned to the gen eral horizon of the Lingula Flags. The results of th e local stratigraphical work up to th is date will be found summarised in th e chapter (much of which is incorporated in the pres ent paper) on the Geology of the Birmingham D istrict in the "Handbook of Birmingham, " prepared for the members of the Bri tish Association
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(in 1886). The subsequent discovery by Lapworth of Olelldlu s and Paradoxides in the Coml ey rocks of Shropshire, led him to assign the Wrekin Quartzite and Comley Limestone to the Lower Cambrian. This was soon followed by the detection of Olendlus in the north-west of Scotland by the officers of the Survey in 1891, led to a renewed search for fossils in the Upper Quartzites of Nuneaton. Casts of fossils were first detected in the bands at the top of the quartzite by Dr. T. Stacey Wilson in 1895 ; and during the same year the more deeply-seated H;'olithus beds of Camp Hill were discovered by Lapworth, and theoretically assigned by him to the Lower Cambrian. In 1895-6 Professor Watts, then of the Geological Survey, revised the geology of the Basement Rock s of Charnw ood Forest, and in the Annua l Report of the Survey for 1896 they are definitely assigned to the pre-Cambrian. In 1897 Mr. Walcot Gibson completed his revision of the Lickey and Barnt Green areas, and in the new edition of Sheet No. 54 N. W. the Barnt Green Rocks are recognised, and the Lickey Quartzite is coloured as Cambrian; while Permian and Bunter beds are shown as existing to the north- east of the Lickey range in ground formerly mapped as Keuper. Coming next to the post-Cambrian formations, we find that the fossils detected by Mr. H. Johnson and Mr. F. G. Meachem in the supposed Permian rocks pierced in the shafts of Sandwell and Harnstead, were studied by Mr. K idston , and the rocks were assigned by him to the Upper Carboniferous. The strata in the neighbourhood of the Forest of Wyre were subsequently investigated by Mr. T. C. Cantrill, who discovered Silurian rocks in all anticline at Trimpley i and a Spirorbts-limestone band, and several distinct coal seams in the so-called Permian rocks of the Enville country. Mr. Wickham King has successfully devoted himself to the investigation of the composition, mode of accumulation, and source of origin, of the Permian Breccia occurring in the many exposures within the limits of the Birmingham District, the Calcareous Conglomerates in the underlying beds, and the remarkable mixed conglom erates of the Upper Coal Measures ; while Mr. R. D. Oldham has published a most interesting comparison of the Permian Boulder beds of the district with the corresponding beds of India, Africa, and Australia. Professor Bonney has investigated the Pebble Beds of the northern part of the distr ict, and Mr. T. Harrison those of the south, and have pu blished their views as to their probable sources and their special mode of origin. The petrology of the rocks of the Permian breccia has been partly worked out by Mr. W. Boulton and by Mr. Harrison, jun., and that of the Pebble Beds by Professor Bonney and by Mr. Waller. Mr. Waller has also published a paper on the intrus ive igneous rocks of the Caldecot e series. Side by side with thi s stratigraphi cal and petrological work,
C. LAPWORTH AND W. W. WATTS ON THE
much has also been done during this period in the study of the Glacial deposits of the District. The original investigations and suggestions of Mackintosh and his predecessors, with regard to the local distribution and probable sources of the Midland erratics, have been greatly extended by the researches and papers of the late Dr. Crosskey and of Mr. W. Jerome Harrison. Mr. Fred Martin has mapped out the main distribution of the Midland erratics, the late Professor Carvill Lewis discussed the arrangement of the Arenig boulders, and Mr. H. G. Mantle has recently investigated the local distribution and probable sources of the erratics in the neighbourhood of Lichfield. REFERENCES. Sheet 8 of the Geological Survey Index Map covers the whole Birmingham area. Price 2S. 6d. Scale, 4 miles to inch. Geological Survey Map (one-inch scale), Sheets 54 N.W. (new edition recently issued), 55 N.E., 61 S.E.,62 S.W.,62 S.E., 63 S.W. (new edition), 3s. each. Ordnance Map, New Series, Sheets 153, 154, 155, 167, 168, 169, 182, 183. Price I s. each. 182 r.
1855·
1856. 1 8 59.
1859· 1865. 1869. 1874. 187+-
1877. 1878.
BUCKLAND, W._u Description of the Qnartz Rock of the Lickey Hill, in Worcestershire, and of the Strata immediately snrronnding it." Trans. Ceo!. Soc., vol. v, p. 5c6. MURCHISON, Sir R. I._H Silurian System." 1839, 4to, London. PHILLIPS, J.- II The Malvern Hills, compared with the Palseozoic Districts of AbberIey." Mem. Geoi, SU1'vey, vol. ii , pt. i, 1848, RAMSAY, [Sir] A. C._uOn the Occnrrence of Angnlar, Subangnlar, Polished, and Striated Fragments and Boulders in the Permian Breccia of Shropshire, Worcestershire, etc." Quart. JOUY1t. Geoi. Soc., vol. xi, 1855, p. 185. BRODIE, P. B._ u Upper Keuper Sandstone of Warwickshire,' Quart. Jour1l. Ceo!. Soc., vol. xii, 1856, p. 374. HOWELL, H. H._u The Geology of the Warwickshire Coalfield." il/em. Geoi. Survey, 1859. JUKES, J. BEETE.-' The Geology of the South Staffordshire Coal. field." Mem. Geoi. Sur~ley, 2nd edition, 1859. BRODIE, P. B._" Lias Outliers at Knowle and Wootton Wawen, etc." Quart. JOU1'1l. Geol. Soc., vol. xxi, 1865, p. 159. HULL, E _" Triassic and Permian Rocks of the Midland Counties of England." Mem. Ceol. Survey, 1869. AL~PORT, S._" The Microscopic Structure and Composition of the British Carboniferous Dolerites.' Quart. Jour1t. Geol. Soc., vol. xxx, 1874, p. 529. MrALL, L. C._" Labyrinthodonts from the Keuper Sandstone in the Warwick Museum.' Quart. Jour1l. Ceo!. Soc., vol. xxx, 1874, p. 4 17. CALLAWAY, C._" On a New Area of Upper Cambrian Rocks in South Shropshire." Quart. Jour1l. Ceol. Soc., vol. xxxiii, 1877, p.65 2. BONNEY, T. G., and Rev. E. HILL.-" On the Pre-Carboniferous Rocks of Charnwood Forest." Quart. JOUI'1t. Geol. Soc., vol. xxxiii, p. 754, etc. CALLAWAY, C._" On the Quartzites of Shropshire." Quart. Jour1l. Gro]. Soc., \'01. xxxiv, 1878, p. 754.
GEOl.OGY OF T HE BJR m N(;HAM DI STRI CT.
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BONNEY, T. G., and E. H ILL II On the Pre-Ca rbonife rous Rocks of Chamwood F orest," Part I I. Qnart. Y our1I. Geo!. S()('., "01. xxxiv, p. 199· 1879. ALLPORT, S _ " The Diorites of t he War wickshire Coalfiel d." Quart, y OI41·n. Geoi. Sc c., vol. xxxv, 1879, p. 637. 187<). CALLAWAY, C .-" T he P re-Cambrian Roc ks of Shropshire," Pa rt r. Quart. :lourn . Geo!. Soc., vol. xxxv, 1879, p. 643. 1879. MAcKrNTosH, D.-" Direct ions a nd Li mits of Dispe rsion, Mode of Occurre nce a nd Relations to D rift Depos its of E rratic Blocks of \V. England and E \Va les." Qllart. 7 0un l. Geo/. Soc., vol. xxxv, 1879, p. 425 . r880. BO:-l NEY, T. G._" On the Pebbles in the Bu nter Bed s." Geol. ltfOf,'., Dec. I I , vol. vii, 1880, p. 404. r880. BONNEY, T . G., and E. H I I. L. "O n the P re-Carbon iferous Rocks of C harnwood Forest," Pa rt I ll . Qsar), ] OU1'1l. Geoi. S oc., vol. xxxvi, p. 33· 1880. ;\f ACKI NTOSH, D ._" Correlation of the Drifts of N. W. E ng land with those of t he Midla nd and East ern Co unties." Qua rt. J Ollrn. Geo!. Soc., vol, xx x vi, p. 178. r882. LAPWORTH, C.-" On the Discovery of Cambrian Rock s in the Neighbourhood of Birmingham." Geo!. Mag, Dec. II , vol, ix, r882, p. 563, an d Proc. B ,-,.111, Ph'-/. Soc., vol. iii, r88r-83, P·234· r882. CALLAWAY, C.-" The ·P re-Cambria n R ocks of Shropsh ire." Part II. Quart. yourn . Geo!. Soc., vo l, xxxviii, 1882, p. rI9. r88 3. CROSSKEY, H . W .- " The Gro oved Blocks and Boulder Clays of Rowley H il L" Pr oc. S'-rm . Phi!. Soc., vol. iii, 188 r-3, p. 459, and vol, iv, P: 69. ' 1883. - - - -- - - - -" O n a Section of Glacia l Drift recen tly exposed in Icknield Street, Birmin gham." Proc, Binn. Phi!. Soc., vol. iii , r88r-3, p. 209. 188 3. H ARRISO N, W . .\.- " On the Qu artz ite Pe bbles contai ned in the Drift and in t he T riassic Strata of E ngb nd, a nd on their Deri vation from an Ancie nt Lan d Ba rrier in Cent ral Eni;la nd." With an addendum by ]. ]. H, Teall. Proc. Birm. Phil. S oc., vol. iii, r881-83, p. 157. IS.o 3. HOUGHTON, F . T . S .-" N ot e 0 11 the Age of the Quartzite of the Licke y. ' Proc, B irm. Phil. S oc., vol. iii, 188r-83, p. 206. (r 882.) r 8 .~3 ·85. MARTIN, F. W. -" T he Geological Sec tion a long th e Wes t Sub urban Rai lway from Birmi ngh am to King's Norton." Proc. B irm. Phi! . Soc., vol. iv, p. 257. r83, . H ARRISON, W .].- " On the Pre-Carboniferous Floor of the Midla nds.' /IIid. Na t., ' -01. viii , p. 38. r885. WALLER, T , H ._ " Ob servations on the Struct ure of tile Rowley Rag." Mid. Nat., vol, viii, p. z6r. r886 H ARRISON, W . J.- " On the Discovery of R ocks of Cambria n Age at Dost hill in Warwicks hire," . Mid. N at., vol, ix, r886, p. 26 r. r8 86. LAPWORTH, C.- H andbook of Birming ham, prepared for the mem bers of the Bri tish Associa tion , 1886. Part III , Geo logy a nd Physiography (Birmi ng ham District) . Edited by Pro f. C. Lapworth, with contributions by S. Allport, W. E. Benton, P. B. Brodie, H. W. Crosskey, W. J. Harrison, and C. J. Wo odwar d. Pp. 213-z65 an d 353-357. With Map, Birmingham. [ Cont ains a Bibliography. ] - - -" On th e Sequence a nd Sys tema tic Position of the r886. Cambrian R ocks of N uneat on. " Geoi. Mag. , Dec., 3, vol, iii, r886, p. 3r9 ; also R ep . Brit. A ssoc., r886 , p. 622. r886. BONNEY, T . G. - Presidential Address to Geological Sec tion, Briti sh Association .
THE GEOLOGY OF THE
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1886. r888. r889· r889· r89I. r89I. r89I.
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STRAHA:-l, A.-" On the Rocks Surrounding the Warwickshire Coalfield and on the Base of the Coal-measures." Geoi. Mag., Dec. 3, vol. iii, r886, p. 540. Rep. Brit. Assoc., 1886, p. 624. With an appendix by F. Rutley. WALLER, T. H.-" Preliminary Note on the Volcanic and Associated Rocks of the Neighbourhood of Nuneaton," Geot, Mag., Dec. 3, vol. iii, r886, p, 322. R. KIDSTON. "On the Fossil Flora of the Staffordshire Coalfields." Trans, Roy. Soc. Edin., vol, xxxv, 1888, pp. 317-335. CROSSKEY, H. W.-" Notes on the Glacial Geology of the Midlands." Proc. Birm, Phil. Soc., vol. vi, 1887-89, p. 169. WALLER, T. H.-" The Petrology of our Local Pebbles," Mid. Nat., vol. xii, 1889, p. 214. LANDON, J.-"The Barr Beacon Beds." Proc. Birm. Phil. Soc., vol. vii, r889-9r, p. II3. BONNEY, T. G., and E. HILL. "On the North-west Region of Charnwood Forest," etc. Quart yourn. Geol. Soc., vol. xlvii, p. 78. MARTIN, F. V\f.-" The Boulders of the Midland District." Proc; Birm Phil. Soc., vol. vi. 1887-89, p. 93, and vol. vii, r889-9r, p.85. KING, W. WICKHAM.-" Clent Hills Breccia." Mid. Nat., vol, xvi, r893, p. 25. OLDHAM, R. D.-" A Comparison of the Permian Breccias of the Midlands with the Upper Carboniferous Glacial Deposits of India and Australia." Quart. Yourn. Geol. Soc., vol. I, r894, p. 463. BONNEY, T. G.-" A Comparison of the Pebbles in the Trias of Budleigh Salterton and of Cannock Chase." Geol. Mag., Dec 4, vol. ii, 1895, p. 75. CANTR11.L, T. C. "On the Occurrence of Spirorbis-Limestone and Thin Coals in the so-called 'Permians' of Wyre Forest," etc. Quart. Journ. Geoi. Soc., vol, li, p. 528. HARRISON, W. J.-" A Bibliography of Midland Glaciology." Proc. Birm, Phil. Soc., vol. ix, r895, p. II6, MANTLE, H. G.-" The Glacial Boulders East of Cannock Chase," with an Appendix on the Petrology by W. Boulton. Proc, Birm. Phil. Soc.,vol. x, 1897, p. 33. WATTS, W. W.-" Notes on the Ancient Rocks of Charnwood Forest." Rep. Brit. Assoc., r896. GEIKIE, SIR A. "Summary of Progress of the Geological Survey," pp. 68 and 69.
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had confounded' with the Old Red Sandstone, as the lower half of the New Red Sandstone, and paralleled the group as a whole with the Rothliegende of Germany. The Permian" trappoid breccia," however, he believed to mark the outcrop of an igneous rock, and he claimed the Lickey Quartzite as being of Silurian age (Llandovery), believing it to graduate upwards into the Llandovery fossiliferous sandstone of Rubery. He suggested that the Lower Lickey Hills lay along an' old volcanic fissure (marked by an igneous rock occurring at Kendal End, near Barnt Green) by which the Silurian beds had been changed into quartzite. A second period in the history of geological research in the Birmingham District is marked by the work of the National Geological Survey. The mapping of the District by the officers of the Survey was carried out between 1840 and 186o, mainly by Sir A. Ramsay, Prof. Jukes, Prof. Hull, Mr. Howell, Prof. Phillips, Sir A. R. Selwyn, and Mr. Aveline. Prof. Phillips mapped the district of the Malvern and Abberley Hills, and described the rocks in the second volume of the Memoirs of the Geological Survey. Jukes (who was a native of Harborne, near Birmingham), mapped the South Staffordshire Coalfield, and his memoir on "The Geology of the South Staffordshire Coalfield," is a model of what such a work should he; but even the second edition has long been out of print. Hull mapped the Leicestershire Coalfield, and (mainly within the limits of the Birmingham District) fixed the boundary between the Permian and Triassic systems, distinguished and named the accepted divisions of the Midland Permian, Bunter and Keuper formations, and ascertained their sequence in the district. His Memoir (1869), " On the Triassic and Permian Rocks ., of the Midland Counties of England, is still the standard work upon the subject. Howell mapped the East Warwickshire Coalfield and the surrounding country, embodying his results in his well-known" Geology of the Warwickshire Coalfield." Ramsay gave a general superintendence to the whole work, and studied personally the more difficult points and problems. The final result of the work of the Surveyors was to place before the public a complete series of geological maps covering the whole area of the Birmingham district, coloured so as to represent not only the various geological systems recognised, but also their main subdivisions. These maps were upon the scale of one inch to the mile-the only scale then published-and when we have regard to the smallness of this scale, and the minute character of the geological work, the general accuracy of the geological lines inserted upon them is beyond all praise. They were illustrated by many coloured longitudinal sections acrossthe more typical parts of the country (upon a scale of six inches to the mile), and by vertical sections
GEOLOGY OF THE BIRMINGHAM DISTRICT.
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(upon a scale of forty feet to the inch) of the strata pierced in the shafts of the chief collieries of the Midlands. During the progress of the Survey many fresh discoveries were made and many novel views brought forward. The Surveyors proved beyond doubt that the "trappoid breccia" of the Permian was not the disintegrated surface of an igneous mass, but formed a constituent stratum of the Permian system. To explain the position and probable mode of formation of this breccia, Ramsay wrote his famous paper upon the subject, in which he advanced the theory of its glacial origin. and suggested its derivation from the distant Longmynd, Caradoc and Wrekin areas of Shropshire. Jukes, on the other hand, was led by his field work to the opposite opinion, namely, that the breccia was probably derived from ancient rocks in the immediate neighbourhood, which were exposed to denudation in the Midland areas during Permian time, but were afterwards buried from sight by later deposits. Again, while Buckland had published his opinion that the Lower Lickey Hills had existed as islands in the New Red Sandstone sea, and were enveloped unconformably in the surrounding mass of New Red -sediments, Ramsay held that the field work showed that they were bounded by faults on both sides, along which they must have been relatively elevated since New Red times. Further, as no stratigraphical break was discoverable at Nuneaton between the Hartshill Quartzite with its associated rocks and the overlying Coal Measures, Ramsay felt himself unable to accept the views of his predecessors that they were of the age of the Wrekin and Lickey Quartzites, and they were consequently coloured by him on the Survey Maps as Millstone Grit and Lower Coal Measures. The period (1856- 1 88 1) which followed the publication of the Survey Maps and Memoirs, was marked by the brilliant petrographical researches of the late Mr. Samuel Allport (a native of the district), and by the discoveries and conclusions of those geologists who were busied in developing the Archrean rocks which existed either within the boundaries of the district or in areas more or less related. Allport's description of the Doterites of the South Staffordshire Coalfield, the Diorites of the Nuneaton district, and of the Rhyolitic lavas and agglomerates of the Wrekin and Wrockwardine areas, are classic in the history of British petrology. Dr. Holl'saccount of the so-called metamorphic gneissose and schistose rocks of the Malvern Hills (published in 1865), in which the original suggestion was made that these rocks were probably of Laurentian or Archsean age, was the pioneer of that host of geological papers dealing with the Archrean and preCambrian rocks of Britain which dominated our geological literature for the next twenty years. In 1876 Dr. Hicks distinguished and named the Pebidian rocks below the Cambrian of St. David's. In 1877-8 Professor Bonney and the Rev. E. Hill published the sequence of the Charnwood Forest rocks, and in 1878 threw out
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C. LAPWORT H ON TH E
the sugges tion that the y might be of Pebidian age. During these years, also, Dr. Callaway published acco unts of his original and far-reac hing researches in Central Shro ps hire. He first an nounced (187 7) his discovery of a typic al T re madoc fauna in the Shineton Shales, and showed ( 1878) that the stratigraphical evidences led to the conclusion that th e Wre kin Quartzite (in place of being of Bala age, as previously supposed) was either of Cam brian age, or more probably, Archsean, Discovering th at the Wrekin "lavas and pyroclasti c rocks (aft erwards named by him Uriconian'j underlay thi s Quartzite unc onformably, he drew (1879) the con clu sion that they mu st be of pre-Cambrian (o r Archrean) age, a con clusion which is now almost universally accepted. In 1880 he sho wed that rock s similar to those of the Wrekin occurred in th e Malvern range near H erefordshire Bea con , overlying the gneissose rocks unconformably. Fo r th is underl ying gneis sose series he had already suggested th e title of .M alvernian ; and a few years lat er he employed the title of Longmyndian, as a designation for th e un alt ered pre-Cambrian rocks of the Longmynd. The final period, nam ely, from th e commencement of 1882 down to the present time, has be en marked mainly by discoveries in th e stratigraphy of the various geological formations of the Birmingham D istr ict and by research es among th e Midland Glacial deposits. We may first tr eat of the Cambrian and preCambrian rocks. Early in J 882 the un conformity betwee n the Llandovery Sandstone of Rubery and the Lickey Q uartzite was d iscovered in the field indep enden tly by Mr. F. T . S. H oughton and by Pr ofessor Lapworth. During th e same year Lapworth detected the bedded pyroclastic basement rocks of Barnt Green in the area in wh ich Murchison had recognised intrusive igneous rock s, bu t which had be en mapped as an outcrop of the Permian breccia. A short time afterwards Lapw orth and Mr. W. J. Harrison ascertained th e bedded nature of the suppose d intrusive igneous rocks of Caldecote near Nuneaton , Lapworth next discovered the Cambr ian fossils of the Stockingford Shales,and work ed out the sequ ence of the beds ; and Harrison discovered the Cambrian inlier of Dost Hill. These results led to a revision of the Nuneaton area by the Geological Survey . In 1885 Mr. A. Strahan re-mapped the area, and pro ved, for the first time, the unconformity between the Cambrian and Ca rboniferous. The officers of the Survey made a collection of the Cambrian fossils of the district, and in the next year (1886) a revised ed ition of Sheet No. 63 S.W. was issued to the public, in which th e rocks were coloured as Lower S iluria n (Cambrian), and assigned to the gen eral horizon of the Lingula Flags. The results of th e local stratigraphical work up to th is date will be found summarised in th e chapter (much of which is incorporated in the pres ent paper) on the Geology of the Birmingham D istrict in the "Handbook of Birmingham, " prepared for the members of the Bri tish Association
GEOLOGY OF THE BIRlIIrNGHAlII DISTRICT.
413
(in 1886). The subsequent discovery by Lapworth of Olelldlu s and Paradoxides in the Coml ey rocks of Shropshire, led him to assign the Wrekin Quartzite and Comley Limestone to the Lower Cambrian. This was soon followed by the detection of Olendlus in the north-west of Scotland by the officers of the Survey in 1891, led to a renewed search for fossils in the Upper Quartzites of Nuneaton. Casts of fossils were first detected in the bands at the top of the quartzite by Dr. T. Stacey Wilson in 1895 ; and during the same year the more deeply-seated H;'olithus beds of Camp Hill were discovered by Lapworth, and theoretically assigned by him to the Lower Cambrian. In 1895-6 Professor Watts, then of the Geological Survey, revised the geology of the Basement Rock s of Charnw ood Forest, and in the Annua l Report of the Survey for 1896 they are definitely assigned to the pre-Cambrian. In 1897 Mr. Walcot Gibson completed his revision of the Lickey and Barnt Green areas, and in the new edition of Sheet No. 54 N. W. the Barnt Green Rocks are recognised, and the Lickey Quartzite is coloured as Cambrian; while Permian and Bunter beds are shown as existing to the north- east of the Lickey range in ground formerly mapped as Keuper. Coming next to the post-Cambrian formations, we find that the fossils detected by Mr. H. Johnson and Mr. F. G. Meachem in the supposed Permian rocks pierced in the shafts of Sandwell and Harnstead, were studied by Mr. K idston , and the rocks were assigned by him to the Upper Carboniferous. The strata in the neighbourhood of the Forest of Wyre were subsequently investigated by Mr. T. C. Cantrill, who discovered Silurian rocks in all anticline at Trimpley i and a Spirorbts-limestone band, and several distinct coal seams in the so-called Permian rocks of the Enville country. Mr. Wickham King has successfully devoted himself to the investigation of the composition, mode of accumulation, and source of origin, of the Permian Breccia occurring in the many exposures within the limits of the Birmingham District, the Calcareous Conglomerates in the underlying beds, and the remarkable mixed conglom erates of the Upper Coal Measures ; while Mr. R. D. Oldham has published a most interesting comparison of the Permian Boulder beds of the district with the corresponding beds of India, Africa, and Australia. Professor Bonney has investigated the Pebble Beds of the northern part of the distr ict, and Mr. T. Harrison those of the south, and have pu blished their views as to their probable sources and their special mode of origin. The petrology of the rocks of the Permian breccia has been partly worked out by Mr. W. Boulton and by Mr. Harrison, jun., and that of the Pebble Beds by Professor Bonney and by Mr. Waller. Mr. Waller has also published a paper on the intrus ive igneous rocks of the Caldecot e series. Side by side with thi s stratigraphi cal and petrological work,
C. LAPWORTH AND W. W. WATTS ON THE
much has also been done during this period in the study of the Glacial deposits of the District. The original investigations and suggestions of Mackintosh and his predecessors, with regard to the local distribution and probable sources of the Midland erratics, have been greatly extended by the researches and papers of the late Dr. Crosskey and of Mr. W. Jerome Harrison. Mr. Fred Martin has mapped out the main distribution of the Midland erratics, the late Professor Carvill Lewis discussed the arrangement of the Arenig boulders, and Mr. H. G. Mantle has recently investigated the local distribution and probable sources of the erratics in the neighbourhood of Lichfield. REFERENCES. Sheet 8 of the Geological Survey Index Map covers the whole Birmingham area. Price 2S. 6d. Scale, 4 miles to inch. Geological Survey Map (one-inch scale), Sheets 54 N.W. (new edition recently issued), 55 N.E., 61 S.E.,62 S.W.,62 S.E., 63 S.W. (new edition), 3s. each. Ordnance Map, New Series, Sheets 153, 154, 155, 167, 168, 169, 182, 183. Price I s. each. 182 r.
1855·
1856. 1 8 59.
1859· 1865. 1869. 1874. 187+-
1877. 1878.
BUCKLAND, W._u Description of the Qnartz Rock of the Lickey Hill, in Worcestershire, and of the Strata immediately snrronnding it." Trans. Ceo!. Soc., vol. v, p. 5c6. MURCHISON, Sir R. I._H Silurian System." 1839, 4to, London. PHILLIPS, J.- II The Malvern Hills, compared with the Palseozoic Districts of AbberIey." Mem. Geoi, SU1'vey, vol. ii , pt. i, 1848, RAMSAY, [Sir] A. C._uOn the Occnrrence of Angnlar, Subangnlar, Polished, and Striated Fragments and Boulders in the Permian Breccia of Shropshire, Worcestershire, etc." Quart. JOUY1t. Geoi. Soc., vol. xi, 1855, p. 185. BRODIE, P. B._ u Upper Keuper Sandstone of Warwickshire,' Quart. Jour1l. Ceo!. Soc., vol. xii, 1856, p. 374. HOWELL, H. H._u The Geology of the Warwickshire Coalfield." il/em. Geoi. Survey, 1859. JUKES, J. BEETE.-' The Geology of the South Staffordshire Coal. field." Mem. Geoi. Sur~ley, 2nd edition, 1859. BRODIE, P. B._" Lias Outliers at Knowle and Wootton Wawen, etc." Quart. JOU1'1l. Geol. Soc., vol. xxi, 1865, p. 159. HULL, E _" Triassic and Permian Rocks of the Midland Counties of England." Mem. Ceol. Survey, 1869. AL~PORT, S._" The Microscopic Structure and Composition of the British Carboniferous Dolerites.' Quart. Jour1t. Geol. Soc., vol. xxx, 1874, p. 529. MrALL, L. C._" Labyrinthodonts from the Keuper Sandstone in the Warwick Museum.' Quart. Jour1l. Ceo!. Soc., vol. xxx, 1874, p. 4 17. CALLAWAY, C._" On a New Area of Upper Cambrian Rocks in South Shropshire." Quart. Jour1l. Ceol. Soc., vol. xxxiii, 1877, p.65 2. BONNEY, T. G., and Rev. E. HILL.-" On the Pre-Carboniferous Rocks of Charnwood Forest." Quart. JOUI'1t. Geol. Soc., vol. xxxiii, p. 754, etc. CALLAWAY, C._" On the Quartzites of Shropshire." Quart. Jour1l. Gro]. Soc., \'01. xxxiv, 1878, p. 754.
GEOl.OGY OF T HE BJR m N(;HAM DI STRI CT.
rS7S.
BONNEY, T. G., and E. H ILL II On the Pre-Ca rbonife rous Rocks of Chamwood F orest," Part I I. Qnart. Y our1I. Geo!. S()('., "01. xxxiv, p. 199· 1879. ALLPORT, S _ " The Diorites of t he War wickshire Coalfiel d." Quart, y OI41·n. Geoi. Sc c., vol. xxxv, 1879, p. 637. 187<). CALLAWAY, C .-" T he P re-Cambrian Roc ks of Shropshire," Pa rt r. Quart. :lourn . Geo!. Soc., vol. xxxv, 1879, p. 643. 1879. MAcKrNTosH, D.-" Direct ions a nd Li mits of Dispe rsion, Mode of Occurre nce a nd Relations to D rift Depos its of E rratic Blocks of \V. England and E \Va les." Qllart. 7 0un l. Geo/. Soc., vol. xxxv, 1879, p. 425 . r880. BO:-l NEY, T. G._" On the Pebbles in the Bu nter Bed s." Geol. ltfOf,'., Dec. I I , vol. vii, 1880, p. 404. r880. BONNEY, T . G., and E. H I I. L. "O n the P re-Carbon iferous Rocks of C harnwood Forest," Pa rt I ll . Qsar), ] OU1'1l. Geoi. S oc., vol. xxxvi, p. 33· 1880. ;\f ACKI NTOSH, D ._" Correlation of the Drifts of N. W. E ng land with those of t he Midla nd and East ern Co unties." Qua rt. J Ollrn. Geo!. Soc., vol, xx x vi, p. 178. r882. LAPWORTH, C.-" On the Discovery of Cambrian Rock s in the Neighbourhood of Birmingham." Geo!. Mag, Dec. II , vol, ix, r882, p. 563, an d Proc. B ,-,.111, Ph'-/. Soc., vol. iii, r88r-83, P·234· r882. CALLAWAY, C.-" The ·P re-Cambria n R ocks of Shropsh ire." Part II. Quart. yourn . Geo!. Soc., vo l, xxxviii, 1882, p. rI9. r88 3. CROSSKEY, H . W .- " The Gro oved Blocks and Boulder Clays of Rowley H il L" Pr oc. S'-rm . Phi!. Soc., vol. iii, 188 r-3, p. 459, and vol, iv, P: 69. ' 1883. - - - -- - - - -" O n a Section of Glacia l Drift recen tly exposed in Icknield Street, Birmin gham." Proc, Binn. Phi!. Soc., vol. iii , r88r-3, p. 209. 188 3. H ARRISO N, W . .\.- " On the Qu artz ite Pe bbles contai ned in the Drift and in t he T riassic Strata of E ngb nd, a nd on their Deri vation from an Ancie nt Lan d Ba rrier in Cent ral Eni;la nd." With an addendum by ]. ]. H, Teall. Proc. Birm. Phil. S oc., vol. iii, r881-83, p. 157. IS.o 3. HOUGHTON, F . T . S .-" N ot e 0 11 the Age of the Quartzite of the Licke y. ' Proc, B irm. Phil. S oc., vol. iii, 188r-83, p. 206. (r 882.) r 8 .~3 ·85. MARTIN, F. W. -" T he Geological Sec tion a long th e Wes t Sub urban Rai lway from Birmi ngh am to King's Norton." Proc. B irm. Phi! . Soc., vol. iv, p. 257. r83, . H ARRISON, W .].- " On the Pre-Carboniferous Floor of the Midla nds.' /IIid. Na t., ' -01. viii , p. 38. r885. WALLER, T , H ._ " Ob servations on the Struct ure of tile Rowley Rag." Mid. Nat., vol, viii, p. z6r. r886 H ARRISON, W . J.- " On the Discovery of R ocks of Cambria n Age at Dost hill in Warwicks hire," . Mid. N at., vol, ix, r886, p. 26 r. r8 86. LAPWORTH, C.- H andbook of Birming ham, prepared for the mem bers of the Bri tish Associa tion , 1886. Part III , Geo logy a nd Physiography (Birmi ng ham District) . Edited by Pro f. C. Lapworth, with contributions by S. Allport, W. E. Benton, P. B. Brodie, H. W. Crosskey, W. J. Harrison, and C. J. Wo odwar d. Pp. 213-z65 an d 353-357. With Map, Birmingham. [ Cont ains a Bibliography. ] - - -" On th e Sequence a nd Sys tema tic Position of the r886. Cambrian R ocks of N uneat on. " Geoi. Mag. , Dec., 3, vol, iii, r886, p. 3r9 ; also R ep . Brit. A ssoc., r886 , p. 622. r886. BONNEY, T . G. - Presidential Address to Geological Sec tion, Briti sh Association .
THE GEOLOGY OF THE
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1886. r888. r889· r889· r89I. r89I. r89I.
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r897· r898.
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STRAHA:-l, A.-" On the Rocks Surrounding the Warwickshire Coalfield and on the Base of the Coal-measures." Geoi. Mag., Dec. 3, vol. iii, r886, p. 540. Rep. Brit. Assoc., 1886, p. 624. With an appendix by F. Rutley. WALLER, T. H.-" Preliminary Note on the Volcanic and Associated Rocks of the Neighbourhood of Nuneaton," Geot, Mag., Dec. 3, vol. iii, r886, p, 322. R. KIDSTON. "On the Fossil Flora of the Staffordshire Coalfields." Trans, Roy. Soc. Edin., vol, xxxv, 1888, pp. 317-335. CROSSKEY, H. W.-" Notes on the Glacial Geology of the Midlands." Proc. Birm, Phil. Soc., vol. vi, 1887-89, p. 169. WALLER, T. H.-" The Petrology of our Local Pebbles," Mid. Nat., vol. xii, 1889, p. 214. LANDON, J.-"The Barr Beacon Beds." Proc. Birm. Phil. Soc., vol. vii, r889-9r, p. II3. BONNEY, T. G., and E. HILL. "On the North-west Region of Charnwood Forest," etc. Quart yourn. Geol. Soc., vol. xlvii, p. 78. MARTIN, F. V\f.-" The Boulders of the Midland District." Proc; Birm Phil. Soc., vol. vi. 1887-89, p. 93, and vol. vii, r889-9r, p.85. KING, W. WICKHAM.-" Clent Hills Breccia." Mid. Nat., vol, xvi, r893, p. 25. OLDHAM, R. D.-" A Comparison of the Permian Breccias of the Midlands with the Upper Carboniferous Glacial Deposits of India and Australia." Quart. Yourn. Geol. Soc., vol. I, r894, p. 463. BONNEY, T. G.-" A Comparison of the Pebbles in the Trias of Budleigh Salterton and of Cannock Chase." Geol. Mag., Dec 4, vol. ii, 1895, p. 75. CANTR11.L, T. C. "On the Occurrence of Spirorbis-Limestone and Thin Coals in the so-called 'Permians' of Wyre Forest," etc. Quart. Journ. Geoi. Soc., vol, li, p. 528. HARRISON, W. J.-" A Bibliography of Midland Glaciology." Proc. Birm, Phil. Soc., vol. ix, r895, p. II6, MANTLE, H. G.-" The Glacial Boulders East of Cannock Chase," with an Appendix on the Petrology by W. Boulton. Proc, Birm. Phil. Soc.,vol. x, 1897, p. 33. WATTS, W. W.-" Notes on the Ancient Rocks of Charnwood Forest." Rep. Brit. Assoc., r896. GEIKIE, SIR A. "Summary of Progress of the Geological Survey," pp. 68 and 69.