Siluria. The history of the oldest known rocks containing organic remains, with a brief sketch of the distribution of Gold over the Earth

Front matter

T SILURIA. THE HISTORY OF THE OLDEST KNOWN ROCKS CONTAINING ORGANIC REMAINS, WITH A B-JJEF SKETCH OF THE DISTRIBUTION OF GOLD OVER THE EARTH. BY SIR RODERICK IMPEY MURCHISON, G.C.S^S.; P.C.L.; M.A.; F.R.S. ; F.LS.; HON. MEM. E.S, ED.; B.I.A.; EX-PRESIDENT OP THE GEOLOGICAL AND ROYAL GEOGRAPHICAL SOCIETIES OF LONDON ; TRUSTEE OP THE BRITISH MUSEUM : HON. MEMBER OF THE ACADEMIES AND NAT. HIST. SOCIETIES OF ST. PETERSBURG, MOSCOW, BERLIN, BRESLAU, COPENHAGEN, HOLLAND, SWITZERLAND, TURIN, BOSTON, NEW YORK, PHILADELPHIA, ETC. ETC. ; AND CORR. INSTITUTE OF FRANCE. " Where were we when these grains of sand were assorted ? Compared with their date, the fall of Babylon has just happened, and the Creation of man is an event of yesterday 1 " Geology, Rev. D. King, 4th edit. p. 116. LONDON: JOHN MURRAY, ALBEMARLE STREET. 1854.

A. and G. A- Spotti swoons, New-street-Square. 2.rt_icalion. TO SIR HENRY THOMAS DE LA BECHE, C.B. F.R.S. DIRECTOR GENERAL OF H. M. GEOLOGICAL SURVEY, &C. &C. &C. To you, my dear De la Beche, who, by your labours and those of your associates, have demonstrated the wide ex tension of the Silurian Rocks in the British Isles, I dedicate this work ; referring my readers to the instructive .National Geological Museum of your foundation, for complete evidence of the truths I have endeavoured to sustain. RODERICK IMPEY MURCHISON. May 1. 1854. A

Preface

. The design of this work is sufficiently explained in the Introductory Chapter. I would here, however, make a few additional remarks, if only to express my great obligations to some of the authors referred to in the subsequent pages. And first to my friend, Mr. J. W. Salter, for his assistance and advice in describing, grouping, and comparing the fossils, all the most characteristic forms of which he has himself selected and drawn on wood. These woodcuts contain small figures either of species which have been discovered in the Silurian rocks of Britain since my former work was published, or of which better specimens have been obtained. The original typical forms so admirably delineated, according to their natural size, by Mr. James De C. Sowerby, in the ' Silurian System,' have been transferred from his etchings on copper to lithographic stones ; and being classified and re-arranged, are presented in thirty-seven plates at the end of this volume.

In regard to its illustrations, therefore, the 'Siluria' now offered to the public is a faithful outline of my previous labours and also of our present knowledge of the older palæozoic rocks, as registered in the noble series of organic life collected in the Government Museum of Practical Geology. The chief deficiency in this part of the work, which my old friends will remark, is the absence of the beautiful lithographs of the Corals of the ' Silurian System,' drawn under the superintendence of my able associate, Mr. Lonsdale, and so lucidly described by him. These zoophytes not having been etched on copper, like the other organic remains, could not be trans ferred ; and a selection has, therefore, been made of the most typical forms only, as represented in certain woodcuts. In naming and describing them, a few errata, alluded to in the volume, would have been avoided, had I A

PREFACE.

. VI submitted the proofs, while going through the press, to the critical eye of the same valued friend, whose assistance was of so much service to me in preparing the original ' Silurian System,' and who, notwithstanding his state of health and absence from London, has kindly enabled me to make those corrections. But passing over these and other defects, which might have been avoided had I been less engaged in different occupations, I trust that my main object will have been obtained, in presenting a clear, general view of the succession of primeval life, and in rendering the earlier pages of geological history accessible to many readers. To render the work a vade mecum of geologists, on which foreigners, as well as my countrymen, might depend, a coloured map is annexed, which is simply a reduction of the geological map of Wales and the adjacent region of Britain prepared by Professor Ramsay and the Government Surveyors, under Sir H. T. De la Beche, and wherein the order of the Silurian Rocks and their relations to overlying deposits are best displayed.

The reader who may wish to examine the details of any one district, has only to look at the large figures inscribed on this map, which refer him to each sheet, illustrated in detail by the Government geologists. The friends who supported me when I ventured to prepare my original map of the Silurian region (at a time when a large portion of the country had not even been represented in the Ordnance maps) will observe that the main features of the range of the Silurian Rocks (Lower and Upper), and their relations to overlying deposits, remain as I had traced them. The fundamental change made by my successors is, that nearly all the "Welsh country coloured in my original map as the Cambrian of Sedgwick, and supposed to be occupied by rocks lower than those I described has been shown to be composed of their exact equivalents.

In other words, the tract ex tending westwards from the Longmynd, which I long ago reduced to order, as best exhibiting the Cambrian and Lower Silurian types of Shrop shire and Montgomeryshire, contains the same geological series as the mountains of N. Wales; the Cambrian rocks and the eqnivalent of the Lingula flags, (lowest Silurian of the Survey), both inclusive. It has truly been a subject of deep regret to me, that an old and cherished friend, with whom I had long worked in foreign as well as British lands, and whose powerful mind and brilliant eloquence have thrown so much light on the science which we mutually cultivate, should, of late years, have so strenuously objected to this application of the term Lower Silurian. But here the reader must remember, that the question

PREFACE.

. VII has been determined by many competent and independent authorities, all of them equally the friends of my distinguished associate as of myself. They have, in short, extended to the more complicated regions of Wales, the cession which I originally described in memoirs, map, and sections, illustrative of the adjacent Silurian counties.* Indicating, as I have always done, a great difference in the organic re mains of the Lower and Upper Silurian, I firmly adhere to my old view of the union of these two groups in one system of life. Aloof from their common fades, a careful revision of all the Silurian fossils in the Government Museum, collected from various parts of the British Isles, has led the palæontologists of that institution to the belief, that nearly one hundred species are common to the Lower and Upper divisions of the Silurian system ; even excluding the Upper Caradoc, or intermediate zone, from the estimate. [See also the work, ' The Palæozoic Fossils of the Cambridge Museum,' and the Tabular List, with comments, in the Appendices A., B.] Those persons who may wish to trace the historical evidences relating to the original researches, will do well to read a condensed sketch by that sound geologist, one of my first instructors, Dr. Fittonf, who clearly ex posed the state of the subject in the year 1841, correctly noticing the effect also produced by other early labourers in the same field, among whom my most efficient coadjutor was the Rev. T. T. Lewis, of Aymestry.

On the other hand, in addition to the various communications by Professor Sedgwick and myself, practical geologists will peruse with interest the memoirs of Bowman, Sharpe, and other authors published in the Pro ceedings and Journal of the Geological Society of London ; as well as the work of Professor Phillips ' On the Malvern and Abberley Hills,' a truly philosophical view of that Silurian region. One of the most successful efforts to apply the true palæozoic succession to a distant part of Europe was made by my eminent and lamented friend Leopold von Buch %, who, simply by comparing fossils sent to him by General Tcheffkine with the types published in my former work, demonstrated that true Silurian rocks were developed in various parts of Russia. The work on Russia and the Ural Mountains, by my associates de Ver neuil, von Keyserling, and myself, was, however (I hope I may say it * See some good general recent observations bearing on this question, by J.B. Jukes, F.R.S. (Journ.

Geol. Soc. Dublin, vol. vi;, President's Discourse, p. 88.). t Edinburgh Review, April, 1841, vol. cxlvii. p. 1. ; see also Quarterly Review, 1839, vol. Ixiv., p. 102. X Beitrage Gebirgs-formationen in Eussland, Berlin, 1810. a

PREFACE.

. without presumption), the first which, in extending those results to the north-western edge of Asia, developed a complete ascending series over the larger half of Europe, from the oldest known fossiliferous strata to the youngest tertiary deposits. In perusing the fifteenth and sixteenth chapters, which indicate the parallelism of the palæozoic rocks of France, Spain, and the United States of America to those of Britain, geologists will at once recognize the vast amount of knowledge which has been contributed by my dear and en lightened companion, M. Edouard de Verneuil. To my other numerous foreign contemporaries, and especially to M. Bar rande, who have seen reason to apply to their own lands the classification and nomenclature first elaborated in the ancient kingdom of the Silures, I also tender my grateful acknowledgments.

May the following pages not be without use in stimulating them to bring the older rocks of their re spective countries into a closer comparison with our British types, than I have been able to effect in the present outline! i TABLE OF CONTENTS.

Chapter I

Page 1 Introduction — Original Silurian Researches. — Design of this work CHAP. II. Babe op the Silurian Rocks, and Earliest Zone of former Life. Outlines, Structure, and Order of the older Rocks. — Earliest Crystalline Rocks. — The lowest Deposits in which a true Sedimentary Origin is seen are usually void of Signs of former Life. Order of Succession from such Unfossiliferous Strata upwards to the lowest Zone in which Fossil Remains have been detected in Great Britain - - - - 17 CHAP. III. Lower Silurian Rocks — continued. The Llandeilo Formation, its Slates, Schists, Sandstones, Limestones, and Interpolated Igneous Rocks. (2" and 2 of Map and Coloured Sections.) - 45 CHAP. IV. Lower Silurian Rocks — continued. The Caradoc Formation. Caradoc Sandstone as developed in North Wales and Radnorshire.

Types of the Formation in Shropshire, Herefordshire, &c. The Caradoc strictly united with the lower Deposits by its Structure and Fossil Contents ------- TABLE OF CONTENTS. X CHAP. V. Upper Silurian Rocks. Page General Character of the Upper Silurian Rocks, as divided into the Wenlock and Ludlow Formations The Wenlock Formation of Shale and Limestone, with its chief Fossils, described in ascending Order ----------- 100 CHAP. VI. Upper Silurian Rocks — continued. The Ludlow Formation, General Character of. Its Subdivision in the Typical Districts, into Lower Ludlow Rocks, Aymestry Limestone, and Upper Ludlow Rocks --..---- 124 CHAP. VII. Silurian Rocks of Britain beyond the Ttpical Region of England and Wai.es, as seen in Cornwall, the North-west of England, Scotland, and Ireland .---_----.-. 144 CHAP. VIII.

Organic Remains of the Lower Silurian Rocks - - - - -176 CHAP. IX. Fossils of the Upper Silurian Rocks ------- 207 CHAP. X. The Devonian Rocks, or Old Red Sandstone, as Exhibited in the British Isles - .-----------_. 241 CHAP. XL Carboniferous Rocks. Great Primeval Flora the Source of the Old Coal Deposits. — General View of these Deposits and their Organic Remains in the British Isles ----- TABLE OF CONTENTS. XI CHAP. XII. Permian Rocks. Page Changes of the Surface before the Permian Deposits were accumulated. — Origin of the Term Permian as applied to the highest Group of Primeval Deposits. — The Permian Rocks of Russia, Germany, and England. — The Organic Remains of the Group ------ ---... 289 CHAP. XIII. General View of the Silurian, Devonian, and Carboniferous Rocks of Scandinavia and Russia --- -.-. ... 315 CHAP. XIV.

Primeval Succession in Germany and Belgium. General Sketch of the Character of the Older Rocks extending westwards from Poland and Turkey in Europe into the Alps and Carpathians. Devonian, Carboniferous, and Permian Rocks of Silesia and Moravia. Silurian Rocks (Lower and Upper) of Bohemia. Lower Silurian, Devonian, Carboniferous, and Permian Rocks of Saxony, the Thuringerwald, &c. General View of the Succession of Devonian and Carboniferous Rocks in the Rhenish Provinces and Belgium - 336 CHAP. XV. Silurian, Devonian, and Carboniferous Rocks of France, Spain, Portugal, and Sardinia ----------- 383 CHAP. XVI. Succession of Primeval Rocks in America. Order of the Palæozoic Strata in South America, the United States, and British North America ------------ 408 CHAP. XVII. On the Original Formation of Gold, and its Subsequent Distribution in Debris over Parts of the Earth's Surface TABLE OF CONTENTS.

CHAP. XVIII. Conclusion. Page Recapitulation — General View of the Succession of Life from a Beginning as based on positive Observation — The Progress of Creation — Theoretical Speculations distinguished from absolute Geological Results ----- 459

Appendix

. A. Vertical Range of Silurian Fossils -------- 485 B. Recent Surveys of the British Silurian Rocks ------ 490 C. Traces of Vegetable Matter in the Silurian and older Rocks - - - - 492 D. Unconformity in Ireland of the Longmynd or Bottom Rocks (' Cambrian ' of the Survey) to the Lower Silurian -------- 493 E. Barrande's Silurian System in .Bohemia -------- 493 F. Depth of the Primeval Seas, and Colouring of the Shells of the Mollusca which lived in them ----------- 495 G. Extension of Silurian Rocks in Spain -------- {J, H. Foraminifera in the Silurian Rocks -------- 496 I. Supposed Anomaly at Neffiez in France explained - - - - .. - 497 K. Australian Gold ------------ ;*J.. L. Produce of Silver ----------- ,J, M. Silurian Rocks in Silesia ---------- ig. N. Palæozoic Rocks in Asia Minor --------- 498 0.

Discoveries along the Flanks of the Malvern Hills ------ ij. P. Other Reptilian Remains in the Permian Rocks of Russia - ib. Q. On the former Changes of the Alps - - - - - . - -499 INDEX LIST OF ILLUSTRATIONS. Geological Map Frontispiece WOODCUTS, Page General Order of the Primeval Rocks 22 Contorted Schists at the South Stack Lighthouse, Anglesea - - 24 The Longmynd - - - 26 Section from the Longmynd on the E.S. E. across the Stiper Stones to the Tract of Shelve and Corndon on theW.N.W. - - - 29 Pass of Llanberis from the Lower Lake - - - - 30 Oldhamia antiqua, from Bray Head, Ireland - - - - 32 Slaty Cleavage and Bedding - - 34 The Western Face of the Stiper Stones 37 The Eastern Face of the Stiper Stones ib. Section of Rocks at Barmouth - 40 Lingula Flags, North Wales - - 42 Hymenocaris vermicauda, Salter.

Lingula Flags, Dolgelly - - 42 Paradoxides Forchhammeri, Angelin? Black Schists of North Wales - 43 Trilobites from the Black Schists of the Malverns - - 43 Lower Silurian Graptolites - - 46 Section at Llandewi Felfrey, Pembrokeshire - - - - 49 Whittery Quarries in Marrington Dingle - - - - 55 Volcanic Breccia - - -56 Ideal Representation of the Manner in which submarine Volcanic Dejections were formed in tti2 Lower Silurian Period - ib. Lower Silurian and bedded Trap, traversed by eruptive Rocks, the Corndon Mountain in the Distance - 57 Alternations of Llandeilo Flags and Schists with Volcanic Grits - ib. View of the Breidden Hills near Welshpool, from Powis Castle - 59 Section across the Breidden Hills - 60 Section across the Gelli Hills - - 61 Lower Silurian Rocks in Abereiddy Bay - - - -6* Llandeilo Schists in Musclewick Bay - 65 View of Skomer Isles, seen from the Mainland - "- - - 66 Page Silurian Rocks of Marloes Bay, Pembroke, dipping under the Old Red Sandstone of 3Hook Point - - G6 Section at Llandewi Felfrey, Pembrokeshire - - - - 68 View from Dynevor Park, Llandeilo, looking to the Hills above Golden Grove - - _ - 69 Noeth Griig - - . - 72 Section near Llangadock.

From the Lower Silurian to the Old Red Sandstone - - - - 73 Section near Llandeilo. From the Lower Silurian to the Edge of the great South-Welsh Coal-field - ib. Llanwrtyd Wells - - - 75 Cader Idris - - - - 77 Llandeilo Schists supporting Caradoc Sandstone - - - - 79 Pegwn's Fawr, Borders of Radnor and Montgomery - - - 80 The Caradoc Range - - - 81 Relations of Caradoc Sandstone to the Upper Silurian Rocks in Shropshire 82 Caradoc Fossils - - - 86 Upper Caradoc Fossils - - 87 Section at Corton - - - 90 Unconformable Relations of Llandeilo Flags and Upper Silurian, near Builth - ib. View of the Malvern Hills from the West - - - - 92 Section from the Malvern Hills to Ledbury - - - - 94 General Order of the Upper Silurian Rocks between the Caradoc Sandstone beneath, and the Old Red Sandstone above them - - 102 Lower Wenlock at Corton, near Presteign .... 103 Altered Amorphous Limestone of Nash Scar - ib.

Section at Yat Hill and Hanter Hill - 104 View from Stanner Rocks (Ousal Wood, Hanter Hill, and Hergest Ridge being successively seen in the Distance) - - - - LIST OF ILLUSTRATIONS. XIV Page overlooking rounded Hills of Upper Silurian ; with Mountains of Old Red Sandstone in the distance, the latter being defined by the untinted outline - ib. Section from the Top of the Silurian Rocks, on the N. W., across the whole area of the Old Red Sandstone, to the bottom beds of the S. Welsh Coal Field, on the SE. - - 243 Section across the Old Red of Forfarshire - - - - 248 Mountains of the West Coast of the Highlands - - - 249 Old Red Sandstone Fish - - 251 Old Red Fish - - - 252 Old Red Ganoid Fish - - 253 Reptile of the Upper Old Red - 254 Old Red Sandstone Plant - - 255 Section across North Devon - - 256 Shells of the Lower Devonian Limestone - 261 Shells of the Upper Devonian Limestone .... 263 Ideal View of the Vegetation of the Carboniferous Era - 268 General Relations of the Carboniferous Rocks in the Central and Southern Parts of England - - - 270 Stackpole Cliffs of Carboniferous Limestone .... 271 Stackpole Rock - - - 272 General Order in Pembrokeshire - ib.

Section across the Cornbrook Coal Basin of the Clee Hills - - 273 Slash of Culm - - - 275 Limulus rotundatus, Prestwich - 281 Coral of the Mountain Limestone - 282 Some Fossils of the Carboniferous Limestone - 283 Insect and Shells of the Coal - - 284 Fern from Coal of Coalbrook Dale - 285 Uppermost Limestone of the Coal 285, 286 The Gurmaya Hills of the South Ural Mountains- ... 295 Section of the West Flank of the South Ural - - - 296 Permian Rocks of Britain - - 300 Relations of Permian Rocks to the Coal near Hales Owen - - 301 Position of the Permian Rocks in Shropshire - - 303 Permian Plants, &c. - 306 Permian Shells ... 309 Permian Fish - - - 312 Lower Silurian Strata of Sweden reposing on Gneiss - - - 318 Oldest Silurian Strata of Sweden resting on Granite - - - 318 Succession in Norway - - 319 Succession in Norway (continued to the east) .-.-.-- 320 Page Section across the elevated Valley of Woolhope - - - - 106 Trilobites of the Lower Wenlock or Woolhope Limestone - - 108 View of Wenlock Edge, as seen from the Hills of Ludlow Rock on the S.W. - - - - 113 Old Quarries in the Wenlock Limestone - - - - 1 1 4 Dudley, from the Wren's Nest - 1 16 Section across the Wren's Nest - 1 1 7 The South End of the Wren's Nest - ib.

Corals of the Wenlock Limestone - 119 120, 121 Ludlow Castle - - - 125 Section across the Ludlow Promontory 126 Whiteway Head - - - 130 The Palmer's Cairn Landslip - 131 Upper Ludlow Rocks at the Bone Well - - - - 134 Brecon Anticlinal of Ludlow Rocks, throwing off Old Red Sandstone - 141 View of the Cliffs near St. Abb's Head 150 Silurian Rocks of the South of Scotland - - - - 152 Section across the Bins of Connemara, and Killery Harbour - - 169 Lower Silurian Zoophytes - - 178 Lower Silurian Crinoid - - 180 Lower Silurian Cystideans - - 181 Lower Silurian Star-fish - - 182 Lower Silurian Orthides - - 184 Lower Silurian Brachiopods - 185, 186, 187, 189 Lamellibranchiata - - - 191 Gasteropoda - - - - 193 Heteropod and Pteropod Mollusca - 196 Cephalopoda - - - - 197 Cephalopods - - - - 199 Anne'ids ; or marine Worm-tracks - ib.

Trilobites typical of the Lower Silurian Rocks - 201 Trinucleus concentricus, three Specimens, distorted by Slaty Cleavage - 203 Other Lower Silurian Trilobites - 204 Section of Stromatopora striatella, D'Orb. - - - - 210 Corals of the Upper Silurian Rocks .212 Cup Corals of the Wenlock Limestone 213 Upper Silurian Bryozoa - - 215 Ptiiodictya scalpelluin, Lonsdale - 216 Cystideæ of the Wenlock Limestone - 217 Crinoidea of the Dudley Limestone - 219 Upper Silurian Starfish - - 221 Upper Silurian Brachiopoda - - 222 Upper Silurian Brachiopoda - - 224 Upper Silurian Lamellibranchiata 225, 226 Upper Silurian Cephalopods - - 231 Upper Silurian Crustacea - - 234 Wenlock Limestone Trilobites - 235 View from the Slaty Lower Silurian Rocks near Llanwrtyd, Brecon, LIST OF ILLUSTRATIONS, XV Lower Silurian Rocks — Cliffs near Waiwara - 324 Asaphus expansus, var. cornutus, from the St. Petersburgh Limestone - ib.

Orthoceras duplex, Wahlenberg - 326 Ravine of the Belaia in the Valdai Hills - - . - 328 Devonian and Carboniferous Rocks in the Gorge of the Tchussovaya River 330 Generalized Section across the Silurian Basin of Central Bohemia - - 342 Inversion in the Eifel explained - 377 Inverted Strata South of Brilon - 378 Section from Sille le Guillaume to Sable' - - - - 385 Page Ideal Section across the Appalachian Chain - 424 General Section across the Older Rocks of Lower Canada near the Mouth of the St. Lawrence - ib. View from the Summit of the Katchkanar, N. Ural - 43# Lake of Aushkul, S. Ural - - 441 Hills of Cossatchi-Datchi - - #,. Diggings at the Soimanof>k Mines - 442 Gold Diggings at Zarevo Alexandrofsk 444 Gold Shingle near Ekaterinburg - 445 Ideal Representation of the Oiiginal Formation of Gold in the Rocks, and its subsequent Translation into Heaps of Gravel - 449 PLATES OF FOSSILS, ETC. [ To be placed at the End of the Book.~\ I. — IV Lower Silurian Crustacea.

V.— VIII „ „ Brachiopoda. IX. — X „ „ Bivalve and Univalve Shells. XI „ „ Cephalopoda. XII „ „ Graptolites and ' Incertæ Sedis.' XIII — XV Upper Silurian Crinoidea and Annelida. XVII.— XIX „ „ Trilobites and Crustacea. XX. — XXII „ „ Brachiopoda and Lamellibranchiata. XXIV. — XXV „ „ Gasteropoda, Pteropoda,' and Heteropoda. XXVI.— XXXIII Cephalopoda. XXXIV Upper Ludlow Rock (Tilestone). XXXV Fossils of Upper Ludlow Bone bed. XXXVI.— XXXVII Fishes of Old Red Sandstone. General Map of Palæozoic Formations. To face p. 475. *a ERRATA. Preface, p. vii. 1. 4. for cession, read succession. Page 167. 1. 5. dele the *. Note. 1. 2. for vol. iv. old ser., read vol. v. 2nd ser. p. 1. et seq. 169. 1. 13. for masses granular, read masses of granular. In the section, for letter o under Glenkeen, read c ; and a letter b should be placed under the dark rocks which rest on the granite (*).

See descr. p. 172. 172. 1. 10. for a, read c. 184. 1. 8. omit 0. flabellulum, f. 1. 187. 1. 4, for last year, read in 1852 (the page was printed in 1853). 188. 1. 6. from bottom for PI. 9., read PI. 6. 192. 1. 2. for Foss. 10., read Foss. 23. 1. 7. for Foss. 12. f. 7., read Foss. 7. f. 12. 195. 1. 18. dele if, f. 7. same species. 196. 1. 6. for triated, read striated. 226. 1. 8. for Mytilus antiquus, read Modiola Page 13. last line, et passim, for mezozoic read mesozoie. 43. last line but one, omit, The Olenus occurs in Bohemia. 44. 1. 3. omit traces. 47. 1. 7. from bottom, for has, read have. 54. 1. 18. read (porphyries of Sedgwick), after igneous rocks. 68. 1. 4. from bottom, for ch. 5., read ch. 8. 74. Note, for PI. 3., read PI. 11. ; also ch. 8. instead of ch. 5. 1. 20. dele Orthis alternata, Foss. 8. ; and 1. 22. dele Asaphus Powisii, pi. 2.

See p. 98. 1. 2. for B. ornatus, Conrad, read B. nodosus, Salter. 1. 5. for next chapter, read chap. 8. 89. 1. 21. for sixth, read fifth. 91. letters under Section near Builth, for c, read d. antiqua. 231. 1. 3. and 12. for Foss. 21., read Foss. 25. 240. 1. 2. from bottom, for in which, read on which. 244. 1. 19. for (g), read (/). 245. 1. 7. for usher into, read usher in. 252. 1. 8. for one sgeciesis, read one species is* 256. 1. 3. of description, place the (*) with * Eruptive granite.' 1. 5. transfer 'Club Mosses' to the Cryptogamæ above. 259. 1. 6. dele in. 286. Note, 1. 2, for tracts, read tracks. 304. 1. 7. from bottom, for do not sto, read do not stop. 305. 1. 17. for that, read those. 308. 1. 2. after Polycœlia dele the semicolon. 310. V9. for Keratophoga, read Keratophaga. 315. P.S., end of, for Ruppendorf, read Ruppersdorf. 322. 1. 19. for on, read in. 323. 1. 4. from . bottom, for Kutorga, read Kutorga. 327. 1. 2. from bottom, for but the, read but to the. 103. 1. 8. for girt, read grit. 105. 1. 5. for amorphorus, read amorphous. 107. 1. 5. et passim, for Petraia bina, Lonsdale, read Petraia bina, sp.

Lonsd. 112. 1. 2. et passim, for Rhynconella, read Rhynchonella. 116. 1. 5. for extended, read extruded. 118. 1. 4. for exterior nucleus, read exterior of the nucleus. 119. 1. 7. from bottom, Fav. cristata,/or Linn., read Blumenbach. 121. Foss. 12. f. 1. the name omitted is Diastopora? consimilis (Aulopora id. Sil. Syst.) The Author isindebted to Mr. Lonsdale for this correction, and also for a suggestion that f. 5. is a distinct species from the S. ramulosa, Goldfuss. 133. 1. 10. /or Avicula reticulata, read Pterinea Sowerbyi. 142. 1. 5. from bottom for fossil, read seedvessel of a plant. 1. 10. from bottom, for Thelodus parvidens, read Onchus Murchisoni. 158. 1. l.for Trenton, read Chazy. 161. 1. 15. for sarcinulata, read lata. 1. 16. for Avicular lineata, read Pterinea (Avicula) lineatula. 163. 1. 7. from bottom, for coniform, read conform. 164. note 2. add and vol. 5. 2nd ser. p. 1. seq. 1. 5. from bottom, for Devonian rocks of Russia, read Devonian and Carboniferous rocks of Russia. 335. 1. 2. for arise, read rise. 371. 1. 10. for its, read the. 401. note, for 1852, read 1853. 421. 1. 11. for Shurman, read Shumard. 508. Index, to references to Dr. Buckland, add Alps, 500. SILURIA.

CHAPTER I.

Introduction

— ORIGINAL SILURIAN RESEARCHES. — DESIGN OF THIS WORK. The earliest conditioa of the earth is necessarily the darkest period of its geological history. The favourite hypothesis concerning the origin of the planet, founded on astronomical and physical analogies, is, that it assumed the form of a flattened spheroid from rotation on its axis when in a fluid state. Reasoning upon this idea, and look ing to the structure of those rocks which either he at great depths or have been extruded from beneath, the geologist has inferred that the crystalline masses, including granites which issued out from be low all other rocks, and constitute possibly their existing substratum, were at one time in a molten state. The theory of a central heat, at first sufficiently intense to maintain the whole terrestrial mass in a state of fusion, but subsequently so far dissipated by radiation into space, as to allow the superficial portion to become solid, has been adopted by the greater number of philosophers who have orappled with the difficult problem of the first conditions of our planet.

Most of them likewise have believed that all the great out bursts of io-neous matter, by which the crust has been penetrated and its surface diversified, were merely outward signs of the con tinued internal activity of that primordial heat, now much repressed B [Chap. 1. SILURIA. by the accumulations of ages, and of which our present volcanoes are feeble indications. If, then, the mathematician has correctly ex plained the causes of the shape of the globe, the geologist confirms his views when, examining into the nature of its oldest massive crystalline rocks, he sees in them clear proofs of the effects of intense heat. This original crust of the earth was subsecpiently, we may believe, broken up by protruded masses, which, issuing in a melted condition, constituted the axes and centres of mountain chains.

Each great igneous eruption gave out substances that became, on cooling, solid rocks, which, when raised into the atmosphere, constituted lands that were exposed to innumerable wasting agencies ; and thus afforded materials to be spread out as deposits upon the shores and bed of the ocean. In these hypothetical views concerning the production of the earliest sediments formed under water, we seem to reach a primary source ; and once admitting that large superficial areas were originally occupied by igneous rocks, we have in them a basis from which the first sedimentary materials were obtained. The earlier eruptions having necessarily occasioned elevations at some points and collapses or depressions at others, such changes of outline, aided by the grinding action of water, would occasion the formation of bands of sediment, which, adapting themselves to the inequalities of the surface, must have been of unequal dimensions in different parts of their range.