Pda ra Ar nee ty : epee ok: Nabe ie atl £ Might: Sais fo Se hee pees oe oa os 2 Pe ies = wae ‘ Prete Wa taire a r ‘ r " Pree ‘ (bi HP esas Mees : Bs we ses = te Ae ae ee 4 CMe heist ee i o>, hE eh he Stans Ay if ate ra ere 4.4 ri vss Paes! pat pb tretane Wa iin Sot othe siotoon : 2 she ate hme) é f ; eine Marat : pn ‘ Fei ; : HONS Winn ‘ Sh f f oh ae 4 ote Re y, cig Meeiete cha i ite es = % wo x coe cx a, es ; Tn se ‘ xiv ; < ~ Stat pgs ES GEE EAM. A reo é ms Eves of pret & ae 1 ry oe, Frontispiece. ac een : Ce eae ane it nt VIEW OF THE TEMPLE OF SERAPIS AT PUZZUOLI IN 1836. See Vol. II. Chap. xxx. PRINCIPLES OF GEOLOGY OR THE MODERN CHANGES OF THE EARTH AND ITS INHABITANTS CONSIDERED AS ILLUSTRATIVE OF GEOLOGY By SIR CHARLES LYELL, Banr. M.A. F-.R.S. eel ‘Ver’ scire est per causas scire ’"—BAc ‘The stony rocks are not ae Fe rhe daughters of Time ’—LInNa&US, Syst. Na ed. 5, Stockholm, 1748, p. 219 * Amid all th volutions of the globe the economy of Nature has been uniform, and her laws are the eat ‘thi ngs that have resisted the general movement. The rivers and the rocks, the seas and the continents, have been changed in all their parts; but the laws which direct those changes, and the rules to which they are subject, have remained invariably the same ’—PLAYFAIR, Jilustrations of the Huitonian Theory, § 374 TENTH AND ENTIRELY REVISED EDITION In Two VotumEs.—Vot. I. z Illustrated with Maps, Plates, and Woodcuts LONDON JOHN MURRAY, ALBEMARLE STREET 1867 The right of translation is reserved D * LONDON PRINPED BY SPOTTISWOODE AND co. NEW-STREET SQUARE PREFACE TO ae PEN DH DUTTON. on It is now thirteen years and a half since the last or ninth edition of the ‘ Principles of Geology’ appeared ; a long inter- val in the history of the progress of a science, in which so many able investigators and thinkers, in every civilised coun- try of the world, are actively engaged. In re-editing the work, I have found it necessary entirely to re-write some chapters and to recast others, and to modify or omit some passages given in former editions. For the sake of those readers who are already familiar with the ‘ Principles,’ I sub- join a list of the chief additions now made for the first time, pointing out the pages at which corresponding matter occurs in the ninth and tenth editions. Inst of the Principal Additions and Corrections in the First Volume of the Tenth Edition of the « Principles of Geology, Ninth iP sae shoal Baition.| Additions and Corrections. Page | Page ra 14 | The opinion of Anaximander, ‘that fish were the parents of ne peep, : zo ow far an anticipation of the modern doctrine velopm es Abeer hits of fossiliferous strata in their order of | 139 | i | superposition, inserted from the ‘ Elements’ for the sake | | | 130 136 to tl a 153 nee. The Ninth Chapter, on the Picaece development of or- ganic life, has been entirely re-writte A 2 iv PREFACE TO THE TENTH EDITION. bee Se Ninth | areas | Edition. |Editio Additions and Corrections. “oF od eee SS ~ Page 73 iz: 4) | The Tenth Chapter (corresponding in part with Chapter VI to | of the former edition) has also been re-wrl itten. It ae 91) | 211 of the changes of climate, established on evidence, organ eee in ai derived from the Tertiary and Post- erate 92) | 212 Thellleventh Chapter is new, treating of the proofs of former wf to vicissitudes in climate, derived from the study of the 1138 J | 282. Secondary and Primary fossiliferous ween. 1137 | 233) | This Twelfth Chapter, on the geographical caus s of forme to to } changes in oe rst ae been re-written. It is 9 illus 130 J} | 267 by t thr maps. 100 | 268) | In this Thirteenth Chapter, to Maa, es are only a few pas an | to } sages corresponding in form editions, I ae considera 126 J | 304 how far former RSE in Toles "may e been in- | fluenced by astro nomical changes; such as iE in | the excentricity of the earth’s orbit changes in the o | quity of the ecliptic, and different phases of the precession | of the equinoxes. Mr roll’s suggestio to ob | eff f a large excentricity in producing glacial epochs is | fully cee and the question is entertained whether | eve ical dates may be obtained, by reference to the com- | ned effect ee astronomical and geographical causes. 204 | 335 The pie te pillars or pyramids of Botzen in the Tyrol and other localities, illustrated by a drawing of Sir John | Herschel’s, are here eines as showing the power of | rain as distinct from that of running water. The glacial origin of the - ymation of which the pillars are made is | also pointed ou 223 | 372 | Notice of the inne of regelation of ee and Faraday | in explanation of “the motion of glaci | 876 | The glacier-lake of the Alps called ‘ the Wis elen See,’ de- | scribed and illustrated by two diagrams, an nd its bearing | on the origin of the parallel roa of Glenroy explained. 5) sh rising in the Artesian wells of the Saha 237 | 398 | Facts relating to the origin of mineral and ene waters | and the hot epaogs of Ba | 420 | Playfair on the origin of the lake-basin of Gene | 434 | Mr. Horner on the mode of conn the anfauile of the Nile mud; with the opin f Mr. e Sharpe, Sir J. | Lubbock, and Mr. We lle a the sae | 447 | A new h ypothesis propos explain the of the | na zen of the mouths of ihe Mississippi, ee | by lap a nd two vl : 971 | 457 | The antiquity 0 of the dela ‘and aoe plain of the Missis- | sippi discussed wit ce new facts brought to | licht during the surv i of Messrs “Humphreys and Abbot, | in 861, and the boring of the Ale at New Or- | leans in 1854, to the depth of 600 feet. 461 | Mr. UL W. Bates ri Professor Agassiz on the delta of the Amazons. Fy ost ibe deposits supposed by Aga siz to a an anc bens ts xe closed by a ternal pape of a glacier conside 279 | 475 | Delta of Fes Ganges—Mr. Fer ‘gusson’s opinions as to the PREFACE TO THE TENTH EDITION. Vv Ninth | Tenth warren Raition. \Edition. Additions and Corrections. Page | Page a tea origin of ‘the sw ee ae the mode of formation of the elevated banks of r 291 495 | V tee elie of Sent i eated of more fully than in the form tion 306 | 514 aes of ais const of Norfolk eae by the ruins of | ese s Church as they appeared in 1889 and in 1862. A | | Michell re iticel-—Vontic—‘Tosto—Whitchurst—Pallao—-Sougeure CONTENTS OF THE FIRST VOLUME. CHAPTER IV. HISTORY OF THE PROGRESS OF GEOLOGY—continued. Werner's ee of Geology to the Art of Mining—Excursive Character of his Lectures—Enthusiasm of his Pupils—His Authority—His Theoretical Errors— er n f the Earth—His Discovery of Granite Veins—Originality of his Views— Wh s Illustrations—Influence of Voltaire’s Writings on Geology—Imputations cast on the Huttonians by Williams, Kirwan, and De Lue—Smith’s Map of England—Geological Society of London—Progress of the Sciences in France—Growing Importance of the Study of — Remains PAGE 68 CHAPTER V. PREJUDICES WHICH HAVE RETARDED THE PROGRESS OF GEOLOGY. ecananiay in regard to the Duration of Past Time—Prejudices arising from our iar Position as Inhabitants of the Land—Others occasioned by our not aon have produced the former Changes of the Earth's Surface, one CHAPTER VI. SUPPOSED INTENSITY OF AQUEOUS FORCES AT REMOTE PERIODS. a sues be Aqueous Causes—Slow Accumulation of ae proved by Fossils— Rat ae can only keep pace with Deposition—Erratics and Action of Ice eee and the Causes to which they are rrel_Suponel U Univer- sality of Ancient Deposits 106 CHAPTER VII. ON THE SUPPOSED FORMER INTENSITY OF THE IGNEOUS FORCES. Voleanic Action at successive Geological Periods—Plutoniec ,Rocks of different Ages—Gradual Development of Subterranean ii of the Sudden Upheaval of Parallel Mountain-chains—Objections to the Proof of the Suddenness of the Upheaval, and th on eaten of Parallel Chains—Trains of Active Volcanos not as © Large Tracts of Land are rising or sinking slowly, so Narrow Zones of Land may be pushed up wpe to Great Heights—Bending of Strata by Lateral Pressure—Adequacy the Voleanie Power to effect this without Paroxysmal Convulsions 117 CHAPTER VIII. DIFFERENCE IN TEXTURE OF THE OLDER AND NEWER ROCKS. Consolidation of Fossiliferous Strata—some Deposits originally solid—Transition Slaty cise re—Crystalline Character of Plutonic and Metamor phic Rocks —Theory of their Origin— Essentially Subterranean—No Proofs that they were produced more eS at remote Perio : 140 CONTENTS OF THE FIRST VOLUME. xi CHAPTER IX. THEORY OF THE PROGRESSIVE DEVELOPMENT OF ORGANIC LIFE AT SUCCESSIVE GEOLOGICAL PERIODS. Theory of the Progressive Development of Organic Life—Kvidence in its Support derived from Fossil Plants—Fossil Animals—Mollusea—Whether they have ad- vanced in Grade since the Earliest Rocks were formed—High Antiquity of Ce- phalopoda—Slight Indications of Progress afforded by Fossil Fish—Advance and Retrogradation of Fossil Reptiles—Land A als of Remote Periods why rare —Fossil Birds -Mammalia—Stonesfield Sioa ahinnhans of Cetacea in Se- condary Rocks—Successive Appearance of the great Sub-classes of Mammalia of advancing Grade in Chronological Order—Modern Gages of Man—Introduc- tion of Man, to what extent a Change in the Syste PA CHAPTER X. FURTHER CONSIDERATION OF THE AGREEMENT OF THE ANCIENT AND MODERN CAUSES OF CHANGE—VICISSITUDES IN CLIMATE. Arguments derived from former Differences in Climate—The Reality of such former Differences considered—Climate a3 hee Ages of Bronze and of Stone— Fossil Quadrupeds and Shells of the Drift—Temperature implied by the Re- mains of the Mammoth and other Extinct oe upeds—-Carcasses of the Ele- phant and Rhinoceros preserved in the Frozen Mud of Siberia—Important Bearing of the Condition of these Fossil Remains on the Theory of Climate— Variation in the Temperature of Post-glacial Times—Organic and Inorganic Proofs of Great Cold in the Glacial Epoch—Inter- elacial Periods of Dirnten and Cromer—British Pliocene Strata, showing Transition from Warmer to Colder Climate—The Signs of Warm Temperature afforded by Italian Pliocene Strata—Warm Climate of Central Europe in Upper Miocene Times—Reptiles and Quadrumana—Fossils of the Siwélik Hills—Upper Miocene Strata of West TIndies—Warm Climate implied by Lower Miocene Fauna and Flora—Miocene Forest Trees in High Arctic Latitudes—High Temperature i the Eocene Period —Supposed Signs of Ice-action implied hid Erratic Blocks of apis Miocene and Middle Eocene Conglomerates . 174 CHAPTER XI. FORMER VICISSITUDES IN CLIMATE—continued. Warm Climate implied by the Fossils of the Chalk—Cretaceous Reptiles—How far extinct Genera and Orders may enable us to infer the Temperature of Ancient Clim ates—Evidence of Floating Ice in the Sea of the White Chalk of England —Warm Climate of the Oolitic and Triassic Periods—Wide Range of the same Fauna from South to North—Abundance and wide Range of Hepes implies a general Absence of severe Cold—The Non-existence of contemporary Mammalia will not explain the Predominance of Reptiles in High Latitudes—Permian Fossils —Supposed signs of Ice-action in the Permian Period—Uniformity of the Fossil Flora over wide Areas—Melville Island Coal-plants—How far the Absence of flowering Plants vitiates our Inferences as to ancient Climates—Whether the CONTENTS OF THE FIRST VOLUME. Atmosphere was subcharged with Carbonic Acid in the Coal Period—Fossi] Shells and Corals of the Carboniferous Strata—Climate implied by the Reptiles or Amphibia of the Coal—Devonian Period, and supposed Signs of Ice-action of that Era considered—Climate of the Silurian Period—Concluding Remarks on the Climates of the Tertiary, Secondary, and Primary Epochs PAGE 212 CHAPTER XII. VICISSITUDES IN CLIMATE CAUSED BY GEOGRAPHICAL CHANGES. On the Causes of Vicissitudes in Climate—On the present Diffusion of Heat over the Globe—Mean Annual Isothermal Lines—Dependence of the Mean Tempera- ture on the relative Position of Land and Sea—Climate of South Georgia and Tierra del Fuego—Cold of the Antarctic Region—Open Sea near the North Pole —FEffect of Currents in equalising the ee of High and Low Latitudes —The present Proportion of Polar land abnormal—Succession of Geographical ae rey oe to us by Geology— oe ie the Am ie of European Land w s been under Water since the Commencement of the Eocene ee of the existing Gontivente: (Chae es in aaa which preceded the Tertiary Epoch—Map showing the ape: Distribution of Land and Water on the Globe—Former Geographical Changes which may have caused the Fluctuations in Climate revealed to us by Golo a eal Map with the Excess of Land removed from Polar to Tropical Regions—Great Depth of the Sea as compared to the Mean Sa of the Land, and its Connection with the Slowness of Climatal Changes 233 CHAPTER XIII. VICISSITUDES IN CLIMATE HOW FAR INFLUENCED BY ASTRONOMICAL CHANGES. The Precession of the Equinoxes, and Variations in the Excentricity of the Earth’s rbit considered as affecting Climate—Under what Conditions Extreme Ex- pecaaed may exaggerate sia teens ement of Heat—Temperature of Space ‘limates of Successive Phases of Precession—Variation in the Obliquity of he Ecliptic—Radiation of Heat impeded by a covering of Snow—Quantity 0 of lar Ice and its Influence in ae the Level of the Ocean—Migrations of a Greenland Whale—Liquefaction and Evaporation of Snow—How far the Dates of former Glacial ae Se may be fixed by computing the Eras of Maxi- um Excentricity—Dates of the Neolithic and Paleolithie Eras-—Of the Inten- sity of Glacial Cold— arene of the Glacial Period as compared to Successive Tertiary, oe and Primary Epochs—Supposed Variations in the Tempe rature of Space—Solar Magnetic Periods and Variable Splendour of the Stars— see an Diminution of the Earth’s Primitive mee osed Change n the Position of the Axis of the Earth’s Crust 268 CHAPTER XIV. UNIFORMITY IN THE SERIES OF PAST CHANGES IN THE ANIMATE AND INANIMATE WORLD. Supposed alternate Periods of Repose and Disorder— Observed Facts in which this Doctrine has originated—These may be explained by supposing a uniform — CONTENTS OF THE FIRST VOLUME. $i ~ ® Ra, and uninterrupted Series of Changes —Threefold Consideration of this Subject ; te, First, in reference to the Laws which govern the Formation of Féaatiitinets a Strata, and the Shifting of the Areas of Sedimentary Deposition; Se scondly, in AG 2h reference to the Living Creation, Extinction of Species, and Origin of New Animals and Plants; Thirdly, in reference to the Changes produced in the Earth’s Crust by the Continuance of Subterranean Movements in certain Areas, bs and their Transference after long Periods to new Areas—On the combined Influence of all these Modes and Causes of Change in producing Breaks and Chasms in the Chain of Records— Concluding Remarks on the Identity of the Ancient and Present System of Terrestrial Changes : : PAGE 305 BOOK II. CHANGES IN THE INORGANIC WORLD NOW IN PROGRESS. CHAPTER XV. AQUEOUS CAUSES. Division of the Subject into Changes of the Organic and Inorganic World—Inor- ganic Causes of ae a into te and Igneo us—Aqueo s Causes oti nih . er 2 first considered—Fall o —Recent Rain-prints in Mud—Earth- soon formed by Rain in ie io and Swiss Alps—Dwarf’s Tower near Viesch— Destroying and “ages Power of ee Water—Newly formed Valleys in Georgia—Sinuosities of Rivers—Two Streams when united do not occupy a Bed of Double Surface— ee in oes caused. . Landslips in the White Mountains—Bursting of a Lake in Switzerland—Devastations caused by the Anio at Tivoli—Excavations in the Layas of Etna by Sicilian he Earthi Rivers—Gorge of the Simeto-—Gradual Recession of the Cataract of Niagara treme Et 827 S ee hg CHAPTER XVI. D yquily ynantity ¢ TRANSPORTATION OF SOLID MATTER BY ICE. rations © Carrying Power of River-Iee—Rocks annually conveyed into the St. Lawrence by yw far © its Tributaries—Ground-Ice ; its Origin and Transporting Power—Glaciers s of Mat Theory of their Downward Movement—Smoothed = Grooved Rocks—The the Intel Moraine Unstratified—Terrace or Beach formed by a Glacier-Lake in Switzer- Success land—Icebergs covered with Mud and Stones—Limits of Glaciers and Icebergs he Tempe —Their Effects on the Bottom when they run aground— Packing of Coast-Ice ne Stat. —Boulders drifted by Ice on Coast of Labrador—Blocks moved by Ice in the ed Chas Baltic . « . . . . . . . . . ° 363 96s CHAPTER XVII. e PHENOMENA OF SPRINGS. ; Origin of Springs—Artesian Wells—Borings at Paris—Live Fish rising in the Artesian Wells in the Sahara—Distinct Causes by which Mineral and Thermal sit Waters may be raised to the Surface—Their Connection with Volcanic Agency in W 1D gif Xlv CONTENTS OF THE FIRST VOLUME. —Thermal Waters of Bath—Calcareous Springs—Travertin of the Elsa. —Baths Gypseo us, Siliceous, and Ferruginous Springs—Brine Springs—Carbonated Sprin pe eet of Granite in Se ae a Lake of Trinidad. F : ; : AGE 387 CHAPTER XVIII. REPRODUCTIVE EFFECTS OF RIVERS. Lake Deltas—Growth of the Delta of the Upper Rhone in the Lake of Geneva— Playfair on the Origin of Lake Basins—Computation of the Age of Deltas— Recent Deposits in Lake Superior—Deltas of Inland Seas—Course of the Po— Artificial Embankments of the Po and Adige—-Delta of the = and other Rivers entering the Adriatic—Rapid Conversion of the Gulf in o Land—Mineral Characters of the New Deposits—Marine Delta of the Fone ee Proofs of its Increase—Stony Nature of its Deposits—Coast of Asia Minor—Delta the Nile—Chronological Computation of the Growth of the ‘Nile Mud 3 Memphis : : : é - : : : : : ; . 416 CHAPTER XIX, REPRODUCTIVE EFFECTS OF RIVERS—continued. Deltas formed under the Influence of Tides—Basin and Delta of the Mississippi Al luvial Plain—River-Banks and Bluffs—Curves of the River—Natural Rafts, w w Orleans—Delta of the Amazons—Delta of the Ganges and Brah- Bi ecipmanr a of the Delta and Sealab ed ds aa formed and destroyed —Crocodiles—Amount of Fluviatile miner in the Water—Artesian Boring at Caleutta—Proofs of Subsidence—Age o elta—Convergence of Deltas— in of existing Deltas not a —Grouping of Strata and Stra- cane in Delne_Conlnee ee ae Bias. of Land and Sea CHAPTER XX. DESTROYING AND TRANSPORTING EFFECTS OF TIDES AND CURRENTS. Differences in the Rise of the Tides—Causes of Currents—-Lagullas and Guif urrents—Velocity of Currents—Action of the Sea on the British Coast—-Shet- land ei taee Blocks removed—Isles reduced to Clusters of Rocks— Orkney Isles—Waste of East Coast of Seotland—and East Coast of England— Vinita of the Cliffs of Holderness, Norfolk, and Suffolk—Eceles Church in 1839 nd 1862—Sand-Dunes how far Chronometers—Silting up of Estuaries— “pasate Estuary—Suffolk Coast—Dunwich— Essex Coast—Estuary of the Thames—Goodwin Sands—Coast of oe ormation of the Straits of Dover— i @ es | J Origin of the South Coast of England—Sussex—Hant —Dorset—Portla Orig Chesil Bank—Torbay—St. Michael’s arose Cornwall Coast of Brittany 498 I CONTENTS OF THE FIRST VOLUME. Xv CHAPTER XXI. ACTION OF TIDES AND CURRENTS—continued. Inroads of the Sea at the Mouths of the Rhine in Holland——-Changes in the Arms of the Rhine—Proofs of Subsidence of Land—Estuary of the Bies Bosch, formed in 1421—Zuyder Zee, in the Thirteenth Century—Islands destroyed—Delta of the Ems converted into a Bay—Estuary of the Dollart formed—Encroachment of the Sea on the Coast of Sleswick—on the Shores of North America—Tidal Wave, called the Bore—Influence of Tides and Currents on the Mean Level of Seas—Action of Currents in can Lakes and eae Pie —Lak » Enie Straits of Gibraltar—No Under-Current there—Varying Depth and Temperature of the enti ‘ ‘ : PAGE 548 CHAPTER XXII. REPRODUCTIVE EFFECTS OF TIDES AND CURRENTS. Depositing Power of Tidal ae up of Estuaries does not compen- sate the Loss of Land on the Borders of the Ocean—Bed o f the German Ocean —Composition and Extent of its Sa - banks—Strata deposited by Currents in the eae Channel—On the Shores of the Mb He besed cen at the Mouths of the Amazons, Orinoco, and a Area over which Strata may be formed by this Cause. : : ; 548 CHAPTER XXIII. IGNEOUS CAUSES. Changes in the Inorganic World, continued—Igneous Causes—Division of the Subj 1 extending from the Aleutian Isles to the Molucca and Sunda Islands—Poly- nesian Archipelago—Volcanic Region extending from Central Asia to the Azores —Tradition of Deluges on the Shores of the Bosphorus, Hellespont, and Grecian sles—Periodical Alternation of Earthquakes in Syria and Southern Italy— Western Limits of the European Region—Earthquakes rarer and more feeble as we recede from the Centres of Volcanic Action—Extinct Volcanos not to be included in Lines of Active Vents CHAPTER XXIV. VOLCANIC DISTRICT OF NAPLES. History of the Volcanic Eruptions i in the District round Naples—Early Convulsions rm e Solfatara—Renewal of the Eruptions of Vesuvius, a.p. 79—Pliny’s Description of the Phenomena—His Silence respecting the Destruction of Herculaneum and Pompeii — Subsequent History of Vesuvius —Lava discharged in Ischia in 1302—Pause in the Eruptions of Vesuvius—Monte Nuovo thrown up—Uni- 7 of the Volcanic Operations of Vesuvius and iS aaciaae Fields in Ancient and Modern Times : : xvi CONTENTS OF THE FIRST VOLUME. CHAPTER XXV. VOLCANIC DISTRICT OF NAPLES—continued. Dimensions and Structure of the Cone of Vesuvius—Fluidity and Motion of Lava— Ropy Scorize—Dikes—Hypothesis of Elevation Craters not applicable to Somma and Vesuvius—Sections seen in Valleys on the North Side of Monte Somma— Alluviums called ‘Aqueous Lavas’—Origin and Composition of the Matter enveloping Herculaneum and Po nai” Conallien and Contents of the buried Cities —Small Number of Skeletons—State of Preservation of Animal and Vege- table Substances — Rolls of Papyrus—Stabize—Torre del em Remarks on the Campanian Volcanos : : ; : GE 620 LIST. OF PiAT ES. Directions to the Binder. Frontispiece. View of the Temple of Serapis, at Puzzuoli, in 1836 : : 3 - : To face Title-Page Prats I,—Map showing the area in Europe which has been pia by water since the beginning of the Eocene Period . To face Page 251 Prare Il.—View of Earth-pillars of Ritten, on the Finsterbach, near Botzen, Tyrol : . To face Page 336 Prare I[I.—Ideal bird’s-eye view of the course of the Niagara River from Lake Erie to Queenstown, show! ae the ravine cut Be the river between Queenstown and the Falls : To face Page 358 Prats IV.--Boulders drifted by ice on shores of the St. Lawrence. : : Zé : a . To face Page 360 Erratum. Page 95, line 31, for ‘inconsistent’ read ‘consistent ” 0% ‘on My e Mis Re PRINCIPLES ad J, ma OF VACA, Ss PARR § re Ody O-G:Y. 2.03000 BOOK I. CHAPTER I. GEOLOGY DEFINED -COMPARED TO HISTORY—ITS RELATION TO OTHER PHYSICAL SCIENCES—NOT TO BE CONFOUNDED WITH COSMOGONY. HOLOGY is the science which investigates the succes- a sive changes that have taken place in the organic and We-riy 4 . : ° ° . inorganic kingdoms of nature ; it enquires into the causes of “ater these changes, and the influence which they have exerted in Page 4 modifying the surface and external structure of our planet. near By these researches into the state of the earth and its in- Py * habitants at former periods, we acquire a more perfect know- from ledge of its present condition, and more comprehensive views river } concerning the laws now governing its animate and inanimate Page * productions. When we study history, we obtain a more pro- F found insight into human nature, by instituting a compa- rison between the present and former states of society. We trace the long series of events which have gradually led to the actual posture of affairs; and by connecting effects with their causes, we are enabled to classify and retain in the memory a multitude of complicated relations—the various peculiarities of national character—the different degrees of moral and intellectual refinement, and numerous other cir- cumstances, which, without historical associations, would be uninteresting or imperfectly understood. Ag the present VOL. I. B Page 9 GEOLOGY COMPARED TO HISTORY. [Cu. I. condition of nations is the result of many antecedent changes, some extremely remote, and others recent, some gradual, others sudden and violent; so the state of the natural world is the result of a long succession of events; and if we would enlarge our experience of the present economy of nature, we must investigate the effects of her operations in former epochs. We often discover with surprise, on looking back into the chronicles of nations, how the fortune of some battle has in- fluenced the fate of millions of our contemporaries, when it has long been forgotten by the mass of the population. With this remote event we may find inseparably connected the eeographical boundaries of a great state, the language now spoken by the inhabitants, their peculiar manners, laws, and religious opinions. But far more astonishing and unexpected are the connections brought to light, when we carry back our researches into the history of nature. The form of a coast, the configuration of the interior of a country, the existence and extent of lakes, valleys, and mountains, can often be traced to the former prevalence of earthquakes and volcanos in regions which have long been undisturbed. To these remote convulsions the present fertility of some districts, the sterile character of others, the elevation of land above the sea, the climate, and various peculiarities, may be distinctly referred. On the other hand, many distinguishing features of the surface may often be ascribed to the operation, at a remote era, of slow and tranquil causes—to the gradual depo- sition of sediment in a lake or in the ocean, or to the prolific increase of testacea and corals. To select another example: we find in certain localities subterranean deposits of coal, consisting of vegetable matter, which formerly grew like peat, in swamps, Or was drifted into seas and lakes. These seas and lakes have since been filled up, the lands whereon the forests grew have been submerged and covered with new strata, the rivers and currents which floated the vegetable masses can no longer be traced, and the plants belonged to species which for ages have passed away from the surface of our planet. Yet the commercial prope, rity, and numerical strength of a nation, may Row be mainly ee — ames ee Cu. I.] GEOLOGY COMPARED TO HISTORY. 8 dependent on the local distribution of fuel determined by that ancient state of things. Geology is intimately related to almost all the physical sciences, as history is to the moral. An historian should, if possible, be at once profoundly acquainted with ethics, poli- ties, jurisprudence, the military art, theology; in a word, with all branches of knowledge by which any insight into hu- man affairs, or into the moral and intellectual nature of man, can be obtained. It would be no less desirable that a geolo- gist should be well versed in chemistry, natural philosophy, mineralogy, zoology, comparative anatomy, botany; in short, in every science relating to organic or inorganic nature. With these accomplishments, the historian and geologist would rarely fail to draw correct and philosophical conclu- sions from the various monuments transmitted to them of former occurrences. They would know to what combination of causes analogous effects were referable, and they would often be enabled to supply, by inference, information con- cerning many events unrecorded in the defective archives of former ages. But as such extensive acquisitions are scarcely within the reach of any individual, it is necessary that men who have devoted their lives to different departments should unite their efforts; and as the historian receives assistance from the antiquary, and from those who have cultivated dif- ferent branches of moral and political science, .so the geolo- gist should avail himself of the aid of many naturalists, and particularly of those who have studied the fossil remains of lost species of animals and plants. The analogy, however, of the monuments consulted in 2eo- logy, and those available in history, extends no farther than to one class of historical monuments—those which may be said to be wndesignedly commemorative of former events. The buried coin fixes the date of the reign of some Roman empe- ror; the ancient éncampment indicates the districts once occupied by invading armies, and the former method of con- structing military defences; the Egyptian mummies throw light on the art of embalming, the rites of sepulture, or the average stature of the human race in ancient Heypt. The canoes and stone hatchets, called celts, found in our peat- B 2 4 GEOLOGY DISTINCT FROM COSMOGONY. [Cu. I. » : bogs and estuary deposits, afford an insight into the rude arts and manners of a prehistoric race, to whom the use of metals was unknown, while flint implements of a much ruder type point to a still earlier period, when man coexisted in Hurope with many quadrupeds long since extinct. This class of me- morials yields to no other in authenticity, but it constitutes a small part only of the resources on which the historian relies, whereas in geology it forms the only kind of evidence which is at our command. For this reason we must not expect to obtain a full and connected account of any series of events beyond the reach of history. But the testimony of geological monuments, if frequently imperfect, possesses at least the ad- vantage of being free from all intentional misrepresentation. We may be deceived in the inferences which we draw, in the same manner as we often mistake the nature and import of phenomena observed in the daily course of nature; but our liability to err is confined to the interpretation, and, if this be correct, our information is certain. It was long before the distinct nature and legitimate ob- . jects of geology were fully recognised, and it was at first con- founded with many other branches of enquiry, just as the limits of history, poetry, and mythology were ill-defined in the infancy of civilisation. Hven in Werner’s time, or at the close of the eighteenth century, geology appears to have been regarded as little other than a subordinate department of mi- neralogy ; and Desmarest included it under the head of Physical Geography. But the most common and serious source of confusion arose from the notion, that 1t was the business of geology to discover the mode in which the earth originated, or, as some imagined, to study the effects of those cosmological causes which were employed by the Author of Nature to bring this planet out of a nascent and chaotic state into a more perfect and habitable condition. Hutton was the first who endeavoured to draw a strong line of demarcation between his favourite science and cosmogony, for he declared that geology was in nowise concerned ‘ with questions as to the origin of things.’ An attempt will be made in the sequel of this work to de- monstrate that geology differs as widely from cosmogony, 4s > Cu. I.] GEOLOGY DISTINCT FROM COSMOGONY. 5 speculations concerning the mode of the first creation of man differ from history. But, before entering more at large on this controverted question, it will.be desirable to trace the progress of opinion on this topic, from the earliest ages to the commencement of the present century. CHAPTER II. ORIENTAL COSMOGONY—HYMNS OF THE VEDAS—INSTITUTES OF MENU—Do¢- F THE THE ANCIENTS ORIENTAL CosmMocony.—the earliest doctrines of the Indian and Egyptian schools of philosophy agreed in ascribing the first creation of the world to an omnipotent and infinite Being. They concurred also in representing this Being, who had existed from all eternity, as having repeatedly destroyed and reproduced the world and all its inhabitants. In the sacred volume of the Hindoos, called the Ordinances of Ment, comprising the Indian system of duties religious and civil, we find a preliminary chapter treating of the Creation, in which the cosmogony is known to have been derived from earlier writings and traditions; and principally from certain hymns of high antiquity, called the Vedas. These hymns were first put together according to Mr. Colebrooke,* in a connected series, about thirteen centuries before the Christian era, but they appear from internal evidence to have been written at various antecedent periods. In them, as we learn from the researches of Professor Wilson, the eminent Sanscrit scholar, two distinct philosophical systems are discoverable. Accord- ing to one of them, all things were originally brought into existence by the sole will of a single First Cause, which ex- isted from eternity; according to the other, there have always existed two principles, the one material, but without * Essays on the Philosophy of the Hindoos. > = —— — Cu. II.] ORIENTAL COSMOGONY. ¢ form, the other spiritual and capable of compelling ‘ inert matter to develope its sensible properties.’ This develop- ment of matter into ‘individual and visible existences’ is called creation, and is assigned to a subordinate agent, or the creative faculty of the Supreme Being embodied in the person of Brahma. In the first chapter of the Ordinances of Ment above alluded to, we meet with the following passages relating to former destructions and renovations of the world :— ‘The Being, whose powers are incomprehensible, having created me (Mend) and this universe, again became absorbed in the supreme spirit, changing the time of energy for the hour of repose. ‘When that Power awakes, then has this world its full expansion ; but when he slumbers with a tranquil spirit, then the whole system fades away..... For while he reposes, as it were, embodied spirits endowed with principles of action depart from their several acts, and the mind itself becomes inert.’ The absorption of all beings into the Supreme essence is then described, and the Divine soul itself is said to slumber and to remain for a time immersed in ‘the first idea, or in darkness.’ After which the text thus proceeds (verse fifty- seven), ‘Thus that immutable power by waking and reposing alternately, revivifies and destroys, in eternal succession, this whole assemblage of locomotive and immovable creatures.’ It is then declared that there has been a long succession of manwantaras, or periods, each of the duration of many thousand ages, and— ‘There are creations also, and destructions of worlds innu- merable: the Being, supremely exalted, performs all this with as much ease as if in sport, again and again, for the sake of conferring happiness.’ * No part of the Eastern cosmogony, from which these extracts are made, is more interesting to the geologist than the doctrine, so frequently alluded to, of the reiterated sub- mersion of the land beneath the waters of an universal ocean. * Institutes of Hindoo Law, or the Ordinances of Ment, from the Sanscrit, translated by Sir William Jones, 1796. : 8 ORIENTAL COSMOGONY. [Cu. IE, In the beginning of things, we are told, the First Sole Cause ‘with a thought created the waters,’ and then moved upon their surface in the form of Brahma the creator, by whose agency the emergence of the dry land was effected, and the peopling of the earth with plants, animals, celestial creatures, and man. Afterwards, as often as a general con- flagration at the close of each manwantara had annihilated every visible and existing thing, Brahma, on awaking from his sleep, finds the whole world a shapeless ocean. Accord- ingly, in the legendary poem called the Puranas, composed at a later date than the Vedas, the three first Avatars or descents of the Deity upon earth have for their object to recover the land from the waters. For this purpose Vishnu is made successively to assume the form of a fish, a tortoise, and a boar. Extravagant as may be some of the conceits and fictions which disfigure these pretended revelations, we can by no means look upon them as a pure effort of the unassisted imagination, or believe them to have been composed without regard to opinions and theories founded on the observation of Nature. In astronomy, for instance, it is declared that, at the North Pole, the year was divided into a long day and night, and that their long day was the northern, and their night the southern course of the sun; and to the inhabitants of the moon, it is said one day is equal in length to one month of mortals.* If such statements cannot be resolved into mere conjectures, we have no right to refer to chance alone the prevailing notion that the earth and its inha- bitants had formerly undergone a succession of revolutions and aqueous catastrophes interrupted by long intervals of tranquillity. Now, there are two sources in which such a theory may have originated. The marks of former convulsions on every part of the surface of our planet are obvious and striking. The remains of marine animals imbedded in the solid strata are so abundant, that they may be expected to force them- selves on the attention of every people who have made some progress in refinement; and especially where one class of * Ment, Inst. c. i. 66, and 67. Cu. IT.] ORIENTAL COSMOGONY. 9 men are expressly set apart from the rest, like the ancient priesthoods of India and Egypt, for study and contemplation. If these appearances are once recognised, it seems natural that the mind should conclude in favour, not only of mighty changes in past ages, but of alternate periods of repose and disorder ;—of repose, when the animals now fossil lived, grew and multiplied—of disorder, when the strata in which they were buried became transferred from the sea to the interior of continents, and were uplifted so as to form part of high mountain-chains. Those modern writers, who are disposed to disparage the former intellectual advancement and civili- sation of Eastern nations, may concede some foundation of observed facts for the curious theories now under considera- tion, without indulging in exaggerated opinions of the pro- eress of science ; especially as universal catastrophes of the world, and exterminations of organic beings, in the sense in which they were understood by the Brahmins, are untenable doctrines. We know that the Egyptian priests were aware, not only that the soil beneath the plains of the Nile, but that also the hills bounding the great valley, contained marine shelis ; and Herodotus inferred from these facts, that all lower Egypt, and even the high lands about Memphis, had once been covered by the sea.* As similar fossil remains occur in all parts of Asia hitherto explored, far in the interior of the continent as well as near the sea, they could hardly have escaped detection by some Hastern sages not less capable than the Greek historian of reasoning philosophically on natural phenomena. We also know that the rulers of Asia were engaged in very remote eras in executing great national works, such as tanks and canals requiring extensive excavations. In the fourteenth century of our era (in the year 1860), the removal of soil necessary for such undertakings brought to light geological facts, which attracted the attention of a people less civilised than were many of the older nations of the Hast. The his- torian Ferishta relates that 50,000 labourers were employed in cutting through a mound, so as to form a junction * Herodot. Euterpe, 12. 10 ORIENTAL COSMOGONY. (Cx. II, between the rivers Selima and Sutlej; and in this mound were found the bones of elephants and men, some of them petrified, and some of them resembling bone. The gigantic dimensions attributed to the human bones show them to haye belonged to some of the larger pachydermata.* But although the Brahmins, like the priests of Egypt, may have been acquainted with the existence of fossil remains in the strata, it is possible that the doctrine of successive destructions and renovations of the world, merely received corroboration from such proofs; and that it may have been originally handed down, like the religious traditions of most nations, from a ruder state of society. The system may have had its source, in part at least, in exaggerated accounts of those dreadful catastrophes, which are occasioned by particular combinations of natural causes. Floods and volcanic erup- tions, the agency of water and fire, are the chief instruments of devastation on our globe. We shall point out in the sequel the extent of many of these calamities, recurring at distant intervals of time, in the present course of nature; and shall only observe here, that they are so peculiarly cal- culated to inspire a lasting terror, and are so often fatal in their consequences to great multitudes of people, that it scarcely requires the passion for the marvellous, so character- istic of rude and half-civilised nations, still less the exuberant imagination of Eastern writers, to augment them into general cataclysms and conflagrations. The great flood of the Chinese, which their traditions carry back to the period of Yaou, something more than 2,000 years before our era, has been identified by some persons with the universal deluge described in the Old Testament; but according to Mr. Davis, who accompanied two of our embassies to China, and who has carefully examined their written accounts, the Chinese cataclysm is therein described as interrupting the business of agriculture, rather than as involving a general destruction of the human race. The * A Persian MS. copy of thehistorian from the library of Tippoo Sultan 1 Ferishta, in the library of the East India 1799; which has been referred to at Company, relating to the rise and pro- some length by Dr. Buckland. (Gee egress of the Mahomedan empire in Trans. 2d Series, vol. ii. part il. p. 389.) India, was procured by Colonel Briggs Cu. II.] ORIENTAL COSMOGONY. 1 great Yu was celebrated for having ‘ opened nine channels to draw off the waters,’ which ‘covered the low hills and bathed the foot of the highest mountains.’ Mr. Davis suggests that a great derangement of the waters of the Yellow River, one of the largest in the world, might even now cause the flood of Yaou to be repeated, and lay the most fertile and popu- lous plains of China under water. In modern times the bursting of the banks of an artificial canal, into which a portion of the Yellow River has been turned, has repeatedly given rise to the most dreadful accidents, and is a source of perpettal anxiety to the government. It is easy, therefore, to imagine how much greater may have been the inundation, if this valley was ever convulsed by a violent earthquake.* Humboldt relates the interesting fact that, after the anni- hilation of a large part of the inhabitants of Cumana, by an earthquake in 1766, a season of extraordinary fertility ensued, in consequence of the great rains which accompanied the subterranean convulsions. ‘The Indians,’ he says, ‘ cele- brated, after the ideas of an antique superstition, by festivals and dancing, the destruction of the world and the approach- ing epoch of its regeneration.’ T The existence of such rites among the rude nations of South America is most important, as showing what effects may be produced by local catastrophes, recurring at distant intervals of time, on the minds of a barbarous and unculti- _ vated race. I shall point out in the sequel how the tradition of a deluge among the Araucanian Indians may be explained, by reference to great earthquake-waves which have repeatedly rolled over part of Chili since the first recorded flood of 1590. The legend also of the ancient Peruvians of an inundation many years before the reign of the Incas, in which only six persons were saved on a float, relates to a region which has more than once been overwhelmed by inroads of the ocean since the days of Pizarro. I might refer the reader to my account of the submergence of a wide area in Cutch so lately as the year 1819, when a single tower only of the fort of Sindree * See Davis on ‘ The Chinese,’ pub- + Humboldt et Bonpland, Voy. Relat. lished by the Soe. for the Diffus, of Use. Hist. vol. i. p. 30. Know, vol. i. pp. 137, 147. 12 EGYPTIAN COSMOGONY. [Cu. I, appeared above the waste of waters, if it were necessary, to prove how easily the catastrophes of modern times might give rise to traditionary narratives, among a rude people, of floods of boundless extent. Nations without written records, and who are indebted for all their knowledge of past events exclusively to oral tradition, are in the habit of confounding in one legend a series of incidents which have happened at various epochs ; nor must we forget that the superstitions of a savage tribe are transmitted through all the progressive stages of society, till they exert a powerful influence on the mind of the philosopher. He may find, in the monuments of former changes on the earth’s surface, an apparent confirma- tion of tenets handed down through successive generations, from the rude hunter, whose terrified imagination drew a false picture of those awful visitations of floods and earth- quakes, whereby the whole earth as known to him was simultaneously devastated. Egyptian Cosmogony.—Respecting the cosmogony of the Hegyptian priests, we gather much information from writers of the Grecian sects, who borrowed almost all their tenets from Heypt, and amongst others that of the former successive de- struction and renovation of the world.* We learn from Plu- tarch, that this was the theme of one of the hymns of Orpheus, so celebrated in the fabulous ages of Greece. It was brought by him from the banks of the Nile; and we even find in his verses, as in the Indian systems, a definite period assigned for the duration of each successive world.t The returns of great catastrophes were determined by the period of the Annus Magnus, or great year—a cycle composed of the revo- lutions of the sun, moon, and planets, and terminating when these return together to the same sign whence they were supposed at some remote epoch to have set. out. The dura- tion of this great cycle was variously estimated. According to Orpheus, it was 120,000 years; according to others, 300,000 ; and by Cassander it was taken to be 360,000 years.} We learn particularly from the Timeus of Plato, that the * Prichard’s Egypt. Mythol. p. 177. Prichard’s Egypt. Mythol p. 182. + Plut. de Defectu Oraculorum, cap. + Prichard’s Egypt. Mythol. p. 182. 12. Censorinus de Die Natali. See also | | Cu. IT.] EGYPTIAN COSMOGONY. 18 Egyptians believed the world to be subject to occasional conflagrations and deluges, whereby the gods arrested the career of human wickedness, and purified the earth from guilt. After each regeneration, mankind were in a state of virtue and happiness, from which they gradually degenerated again into vice and immorality. From this Egyptian doctrine, the poets derived the fable of the decline from the golden to the iron age. The sect of Stoics adopted most fully the system of catastrophes destined at certain intervals to destroy the world. These they taught were of two kinds ;—the Cataclysm or destruction by water, which sweeps away the whole human race, and annihilates all the animal and vegetable productions of nature; and the Ecpyrosis, or destruction by fire, which dissolves the globe itself. From the Hgyptians also they derived the doctrine of the gradual debasement of man from a state of innocence. Towards the termination of each era the gods could no longer bear with the wickedness of men, and a shock of the elements or a deluge overwhelmed them ; after which calamity, Astrea again descended on the earth, to renew the golden age. The connection between the doctrine of successive catas- trophes and repeated deteriorations in the moral character of the human race is more intimate and natural than might at first be imagined. Tor, in a rude state of society, all great calamities are regarded by the people as judgments of God on the wickedness of man. ‘Thus, in our own time, the priests persuaded a large part of the population of Chili, and perhaps believed themselves, that the fatal earthquake of 1822 was a sign of the wrath of Heaven for the great political revolution just then consummated in South America. In like manner, in the account given to Solon by the Egyptian priests, of the submersion of the island of Atlantis under the waters of the ocean, after repeated shocks of an earthquake, we find that the event happened when J upiter had seen the moral depravity of the inhabitants.t Now, when the notion had once gained ground, whether from causes before sug- gested or not, that the earth had been destroyed by several * Prichard’s Egypt. Mythol. p. 198. t Plato’s Timeeus. 14 OPINIONS OF THE GREEKS. Cu. II, general catastrophes, it would next be inferred that the human race had been as often destroyed and renovated. And since every extermination was assumed to be penal, it could only be reconciled with divine justice, by the supposition that man, at each successive creation, was regenerated in a state of purity and innocence. A very large portion of Asia, inhabited by the earliest nations whose traditions have come down to us, has been always subject to tremendous earthquakes. Of the geo- graphical boundaries of these, and their effects, I shall speak in the proper place. Egypt has, for the most part, been exempt from this scourge, and the Keyptian doctrine of great catastrophes was probably derived in part, as before hinted, from early geological observations, and in part from Hastern nations. In the Egyptian and Eastern cosmogonies, and in the Greek version of them, no very definite meaning can, in general, be attached to the term ‘destruction of the world;’ for sometimes it would seem almost to imply the annihilation of our planetary system, and at others a mere revolution of the surface of the earth.* Opinions of the Greeks—Anaaimander. Tn the 8th book of Plutarch’s Symposiacon or ‘Convivial Conversations,’ the question is raised why the Pythagoreans were averse to eating fish, and it is considered whether the prejudice may have had an Egyptian, ora Syrian, or an ancient Greek source. One of the party alludes to the doctrine of Anaxi- mander that ‘ Men were in the beginning engendered in fish, and after they had been nourished and had become able to shift for themselves, they were * Tt is not inconsistent with the Hindoo mythology to suppose that Py- thagoras might have found in the East not only the system of universal and violent catastrophes and periods of repose in endless succession, but also that of periodical revolutions, effectec by the continued agency of ordinary causes. For Brahma, Vishnu, and Siva, the first, second, and third persons of the Hindoo triad, severally represented the Creative, the Preserving, and the cast out and took to the land.’ Destroying powers of the Deity. The coexistence of these three attributes, all in simultaneous operation, might well accord with the notion of perpetual but partial alterations finally bringing about a complete change. But the fic- tion expressed in the verses before quoted from Ment of eternal vicissitudes in the vigils and slumbers of Bramah seems accommodated to the system of great general catastrophes followed by new creations and periods of repose. a Cu. II.] ANAXIMANDER. 15 A suggestion is then made that, as fish were the parents of mankind, Anaximander may have objected to the use of them as food. Such allusions to an ancient doctrine by no means warrant us in assuming that Anaximander had really taught that men should abstain, from such a motive, from eating fish, but they are curious as affording evidence that the Milesian philosopher really believed that men originally sprang from fish. Unfortunately all the works of Anaxi- mander, the pupil of Thales, are lost. He was born 610 years before Christ, and is said to have been the first who left a philosophical treatise in writing. It is only from a few brief citations scattered through the pages of later authors, that we learn anything of his opinions. Eusebius quotes from a lost work of Plutarch called =tpwpartets or ‘ patchwork,’ the following words : ‘Man, according to Anaximander, must have been born from animals of a different form (2& adXoedav tov); for whereas other animals easily get their food by themselves, man alone requires long rearing; and no one being such as he was originally, could have been pre- served.’ * In another work of Plutarch we read as follows: ‘ Anaxi- mander taught that the first animals (ra pata Coa) were begotten in moisture, and were covered with prickly integu- ments, but as they grew older they came out into the dry land, and their integuments were rent asunder.t Censorinus, in his work ‘De Die Natali,’ says that, according to Anaxi- mander, either fish, or animals very like fish, sprang from heated water and earth, and that the human foetuses grew in these animals to a state of puberty, so that when at length they burst, men and women capable of nourishing themselves pro- ceeded from them.{ Full justice cannot, probably, be done to the views of this ancient author by reference to the few meagre fragments of his writings which have alone come down to us, but we trace the same idea running through all of them, namely, the peculiar helplessness of the human infant, making it natural to suppose that there must have been a connection between the embryonic condition of the * Buseb. Evayyedrkhs mpomap. 1-8. chap. 19. + De placidis Philcsophorum, book v. + Censorinus De Die Natali IV. 16 PYTHAGOREAN DOCTRINES. [Cu. IT first human beings and some previously existing animals Anaximander evidently took for granted that man wag no} created in an adult or fully developed state, and in so doin he made at least some slight approach, twenty-five centuries before our time, to the modern doctrine of evolution. But none of the above passages warrant the conclusion that the Greek philosopher had anticipated the Lamarckian theory of progressive development. Yet H. Ritter, writing in 1819,* represents him as having taught that after the first imperfect and short-lived creatures had been engendered in slime, an advance took place from the lower to the higher grades of life, until at length man was formed ; and Cuvier, usually so accurate, but who seems never in this instance to have consulted the original texts, went a step beyond Ritter, and said in 1841, ‘Anaximander pretended that men had been first fish, then reptiles, then mammalia, and lastly what they now are.’ ‘A system,’ he adds, ‘ which we find reproduced in times very near to our own, and even in the nineteenth century.’t Pythagorean Doctrines.— Pythagoras (580? B.c.), wo re- sided for more than twenty years in Egypt, and, according to Cicero, had visited the East, and conversed with the Persian philosophers, introduced into his own country, on his re- turn, the doctrine of the gradual deterioration of the human race from an original state of virtue and happiness ; but if we are to judge of his theory concerning the destruction and renovation of the earth from the sketch given by Ovid, we must concede it to have been far more philosophical than any known version of the cosmogonies of Oriental or Egyp- tian sects. Although Pythagoras is introduced by the poet as deliver- * Ersch and Gruber’s Encyclopedia, le dix-neuviéme Siécle.—Cuvier, Hist. article Anaximander. hae Naturelles, tome i. 1. fT ‘Quoiquil en soit, Anaximandre ay- : ant admis l’eau comme le second prin- ee and Geoffroy St. Hilaire are cipe de la Nature, pretendait que les evidently here alluded to: they had hommes avaient primitivement été derived their theory of progressive poissons, puis reptiles, puis mammifers _ development from geological data, the et enfin ce qu’ils sont maintenant, nous ormer having published his pe in retrouverons ce systéme dans des temps _-1801, and G. St. Hilaire in 1 trés rapprochés des notres et méme dans Cu. II.] PYTHAGOREAN SYSTEM, 17 ing his doctrine in person, some of the illustrations are derived from natural events which happened.-after the death of the philosopher. But notwithstanding these anachronisms, we may regard the account as a true picture of the tenets of the Pythagorean school in the Augustan age ; and although perhaps partially modified, it must have contained the sub- stance of the original scheme. Thus considered, it is ex- tremely curious and instructive ; for we here find a compre- hensive summary of almost all the great causes of change now in activity on the globe, and these adduced in confirma- tion of a principle of a perpetual and gradual revolution inherent in the nature of our terrestrial system. These doctrines, it is true, are not directly applied to the explanation of geological phenomena ; or, in other words, no attempt is made to estimate what may have been in past ages, or what may hereafter be, the aggregate amount of change brought about by such never-ending fluctuations. Had this been the case, we might have been called upon to admire so extra- ordinary an anticipation with no less interest than astrono- mers, when they endeavour to define by what means the Samian philosopher came to the knowledge of the Copernican system. Let us now examine the celebrated passages to which we have been adverting* :— ‘Nothing perishes in this world; but things merely vary and change their form. To be born, means simply that a thing begins to be something different from what it was before; and dying, is ceasing to be the same thing. Yet, although nothing retains long the same image, the sum of the whole remains constant.’ These general propositions are then confirmed by a series of examples, all derived from natural appearances, except the first, which refers to the golden age giving place to the age of iron. The illustrations are thus consecutively adduced. 1. Solid land has been converted into sea. 2. Sea has been changed into land. Marine shells lie far distant from the deep, and the anchor has been found on the summit of hills. * Ovid’s Metamor. lib. 16. VOL. I. C 18 PYTHAGOREAN SYSTEM. (Cx. I 3. Valleys have been excavated by running water, ang floods have washed down hills into the sea.* 4. Marshes have become dry ground. 5. Dry lands have been changed into stagnant pools. 6. During earthquakes some springs have been closed y and new ones have broken out. Rivers have deserted ,their channels, and have been re-born elsewhere ; as the Hrasinug in Greece, and Mysus in Asia. 7. The waters of some rivers, formerly sweet, have become bitter; as those of the Anigris in Greece, &c.+ 8. Islands have become connected with the main land by the growth of deltas and new deposits; as in the case of Antissa joined to Lesbos, Pharos to Egypt, &c. 9, Peninsulas have been divided from the main land, and have become islands, as Leucadia; and according to tradition Sicily, the sea having carried away the isthmus. 10. Land has been submerged by earthquakes ; the Grecian cities of Helice and Buris, for example, are to be seen under the sea, with their walls inclined. 11. Plains have been upheaved into hills by the confined air seeking vent, as at Troezene in the Peloponnesus. 12. The temperature of some springs varies at different periods. The water of others are inflammable.t Some streams make the hair to resemble amber and gold, others influence the mind as well as the body, having some of them an exciting, others a soporific effect. "13. There are streams which have a petrifying power, and convert the substances which they touch into marble. 14. Extraordinary medicinal and deleterious effects are produced by water of different lakes and springs.§ 15. Some rocks and islands, after floating and having been * «Eluvie mons est deductus in eequor,’ + That is probably an allusion to the Ne . The meaning of this last verse escape of inflammable gas, like that is somewhat obscure; but taken with the district of Baku, west of the Cas- the context, may be supposed to allude pian; at Pietramala, the Tuscan to the abrading power of floods, torrents, | Apennines ; and several other places and rivers Many of those deseribed seem overated + Theimpregnation from new mineral fanciful fictions, like the exagge : 3 . + in springs, caused by earthquakes in vol- virtues still attributed to some m canic countries, is perhaps here alluded —_ waters. to. eral Cx. II.] PYTHAGOREAN SYSTEM. 19 subject to violent movements, have at length become stationary and immovable, as Delos, and the Cyanean Isles.* 16. Voleanic vents shift their position; there was a time when Etna was not a burning mountain, and the time will come when it will cease to burn. Whether it be that some caverns become closed up by the movements of the earth, and others opened, or whether the fuel is finally exhausted, &e. &e. The various causes of change in the inanimate world having been thus enumerated, those of the animate creation are next alluded to. The metamorphoses of insects and frogs are mentioned, and some popular notions respecting other changes in the organic world, such as the springing up of the phoenix from the ashes of its parent; but none of the facts or fables have any geological bearing, unless we consider the alleged generation of bees and wasps from the putrid careases of dead cattle and horses, and the originating of snakes from the marrow of the human spine in sepulchres, as implying the adoption of the doctrine of equivocal generation. The transmigration of souls into the bodies of animals is re- ferred to as having been taught by Numa Pompilius. But there is nothing to prove that the Greeks or Romans had any fixed ideas respecting a general change of species having oc- curred in the past history of the globe, still less that there had been a progressive development of life from the lowest to the highest grades of organisation. Xenophanes, a Colophonian who lived s.c. 535, spoke of shells, fishes, and seals which had become dried in mud, and were found inland and on the tops of the highest mountains. Aristotle, in his treatise on respiration, speaks distinctly of fossil fishes; and his pupil Theophrastus, alluding to such fishes found near Heraclea, in Pontus, and in Paphlagonia, says, that they were either procreated from fish-spawn left behind in the earth, or had Raspe, in a learned and judicious tionary, originated in the great change essay (De Novis Insulis, cap. 19), has produced in their form by earthquakes made it appear extremely probable that and submarine eruptions, of which there all the traditions of certain islands in have been 1 i the Mediterranean havin " former time frequently shifted their When the series of convulsions ended, positions, and at length become sta- the island was said to become fixed. c 2 ” iu 2] pa pa = a D pel & = mM ® roy - ct T as 5 S oO ° oa =m = mM ae 9 5 NA 20 ARISTOTELIAN SYSTEM. (Cx, 17 gone astray from rivers or from the sea, for the sake of food into cavities in the earth, where they had become petrified, The same writer, treating of fossil ivory and bones, sup. posed them to be produced by a certain plastic virtue latent in our earth. Opinions of Aristotle. — From the works now extant of Aristotle, and from the system of Pythagoras, as above ex- posed, we might certainly infer that these philosophers con- sidered the agents of change now operating in nature, as capable of bringing about im the lapse of ages a complete revolution; and the Stagyrite even considers occasional ea- tastrophes, happening at distant intervals of time, as part of the regular and ordinary course of nature. The deluge of Deucalion, he says, affected Greece only, and principally the part called Hellas, and it arose from great inundations of 3: rivers during a rainy winter. But such extra y winters, he says, though after a certain period they return, do not always revisit the same places.* Censorinus quotes it as Aristotle’s opinion, that there were general inundations of the globe, and that they alternated with conflagrations; and that the flood constituted the winter of the great year, or astronomical cycle, while the conflagration, or destruction by fire, is the summer or period of greatest heat.t If this passage, as Lipsius supposes, be an amplification, by Censorinus, of what is written in ‘the Meteorics,’ it is a gross misrepresentation of the doctrine of the Stagyrite, for the general bearing of his reasoning In that treatise tends clearly in an opposite direction. He refers to many examples of changes now constantly going on, and insists emphatically on the great results which they must produce in the lapse of ages. He instances particular cases of lakes that had dried up, and deserts that had at length pecome watered by rivers and fertilised. He points to the erowth of the Nilotic Delta since the time of Homer, to the shallowing of the Palus Mzotis within sixty years from bis own time ; and although, in the same chapter, he says nothing of changes in the relative level of land and sea, yet in other parts of the same treatise he speaks of such events in con- + De Die Nat. * Meteor. lib. i. cap. 12, Cu. IT.] ARISTOTELIAN SYSTEM. 94 nection with earthquakes.* He alludes, for example, to the upheaving of one of the Eolian islands previous to a volcanic eruption. ‘The changes of the earth,’ he says, ‘are so slow in comparison to the duration of our lives, that they are over- looked (Nav@avet) 5 and the migrations of people after great catastrophes and their removal to other regions, cause the event to be forgotten.’t When we consider the acquaintance displayed by Aristotle, in his various works, with the destroying and renovating powers of Nature, the introductory and concluding passages of the twelfth chapter of his ‘ Meteorics’ are certainly very remarkable. In the first sentence he says, ‘The distribu- tion of land and sea in particular regions does not endure throughout all time, but it becomes sea in those parts where it was land, and again it becomes land where it was sea: and there is reason for thinking that these changes take place according to a certain system, and within a certain period.’ The concluding observation is as follows :-—* As time never fails, and the universe is eternal, neither the Tanais, nor the Nile, can have flowed for ever. The places where they rise were once dry, and there is a limit to their operations: but there is none to time. So also of all other rivers; they spring up, and they perish ; and the sea also continually deserts some lands and invades others. The same tracts, therefore, of the earth are not, some always sea, and others always continents, but everything changes in the course of time.’ It seems, then, that the Greeks had not only derived from preceding nations, but had also, in some slight degree, deduced from their own observations, the theory of periodical revolutions in the inorganic world: there is, however, no ground for imagining that they contemplated former changes in the races of animals and plants. Even the fact that marine remains were enclosed in solid rocks, although observed by some, and even made the groundwork of geolo- gical speculation, never stimulated the industry or onided. the enquiries of naturalists. It is not impossible that the * Lib. ii. cap. 14, 15, and 16, + Thid. 22 ARISTOTELIAN SYSTEM. [Cu. ID. theory of equivocal generation might have engendered some indifference on this subject, and that a belief in the sponta- neous production of living beings from the earth or corrupt matter, might have caused the organic world to appear so unstable and fluctuating, that phenomena indicative of former changes would not awaken intense curiosity. The Keyptians, it is true, had taught, and the Stoics had repeated, that the earth had once given birth to some monstrous animals, which existed no longer ; but the prevailing opinion seems to have been, that after each great catastrophe the same species of animals were created over again. This tenet is implied in a passage of Seneca, where, speaking of a future deluge, he says, ‘Every animal shall be generated anew, and man free from guilt shall be given to the earth.’* An old Arabian version of the doctrine of the successive revolutions of the globe, translated by Abraham Hechellen- sis,t seems to form a singular exception to the general rule, for here we find the idea of different genera and species having been created. The Gerbanites, a sect of astronomers who flourished some centuries before the Christian era, taught as follows: —‘ That after every period of thirty-six thousand four hundred and twenty-years, there were pro- duced a pair of every species of animal, both male and female, from whom animals might be propagated and inhabit this lower world. But when a circulation of the heavenly orbs was completed, which is finished in that space of years, other genera and species of animals are propagated, as also of plants and other things, and the first order is destroyed, and so it goes on for ever and ever.’ mne ex integro animal generabi- tur, pera terris homo inscius sce- rum.’—Queest. Nat. iii. + This author was Regine Professor of Syriac and Arabic at Paris, where, Arabian MSS. on eo de Lune of philosophy. This work has ys been considered of high au- sais t ‘Gerbanite docebant singulos tri- ginta sex mille annos quadringentos, viginti quinque bina ex singulis anima- lium speciebus produci, marem scilicet tur animalium genera et species, quem- admodum et plantarum aliarumque erum, et primus destruitur ordo, sieque in infinite piedens ur. —Histor. Orient. Suppl. per Abrahamum Ecchellensem, SPECULATIONS OF STRABO. 25 Cu. II.] Theory of Strabo.—As we learn much of the tenets of the Egyptian and Oriental schools in the writings of the Greeks, so, many speculations of the early Greek authors are made known to us in the works of the Augustan and later ages. Strabo, in particular, enters largely, m the second book of his Geography, into the opinions of Bratosthenes and other Greeks on one of the most difficult problems in geology, viz. by what cause marine shells came to be plentifully buried in the earth at such great elevations and distances from the sea. He notices, amongst others, the explanation of Xanthus the Lydian, who said that the seas had once been more exten- sive, and that they had afterwards been partially dried up, as in his own time many lakes, rivers, and wells in Asia had failed during a season of drought. Treating this conjecture with merited disregard, Strabo passes on to the hypothesis of Strato, the natural philosopher, who had observed that the quantity of mud brought down by rivers into the Huxine was so great, that its bed must be gradually raised, while the rivers still continue to pour in an undiminished quantity of water. He, therefore, conceived that, originally, when the Euxine was an inland sea, its level had by this means become so much elevated that it burst its barrier near Byzantium, and formed a communication with the Propontis; and this partial drainage, he supposed, had already converted the left side into marshy ground, and thus, at last, the whole would be choked up with soil. So, it was argued, the Mediter- ranean had once opened a passage for itself by the Columns of Hercules into the Atlantic; and perhaps the abundance of sea-shells in Africa, near the Temple of Jupiter Ammon, might also be the deposit of some former inland sea, which had at length forced a passage and escaped. But Strabo rejects this theory, as insufficient to account for all the phenomena, and he Syrum Maronitam, cap. 7. et 8. ad caleem Chronici Orientali. Parisiis, e Typ. Regia, 1685, fol. i I have given the punctuation as in the Paris edition, there being no comma proposes one of his own, the years, and not to the number of pairs of each species created at one time, as I S. Fortis inferred that twenty-five new species only were created at atime; a construction which the passage will not admit. Mém. sur Hist. Nat. de VItalie, vol..i. p. 202, 24. THEORY OF STRABO. [Cu. Ir, profoundness of which modern geologists are only beginning to appreciate. ‘It is not,’ he says, ‘because the lands eo. vered by seas were originally at different altitudes, that the waters have risen, or subsided, or receded from some parts and inundated others. But the reason is, that the same lang is sometimes raised up and sometimes depressed, and the gea also is simultaneously raised and depressed, so that it either overflows or returns into its own place again. We must therefore, ascribe the cause to the ground, either to that eround which is under the sea, or to that which becomes flooded by it, but rather to that which lies beneath the gea, for this is more movable and, on account of its humidity, can be altered with greater celerity.* It is proper,’ he ob- serves in continuation, ‘ to derive our explanations from things which are obvious, and in some measure of daily occurrence, such as deluges, earthquakes, and volcanic eruptions,t and sudden swellings of the land beneath the sea ; for the last raise up the sea also; and when the same lands subside again, they occa- sion the sea to be letdown. And it is not merely the small, but the large islands also, and not merely the islands, but the continents which can be lifted up together with the sea ; and both large and small tracts may subside, for habitations and cities, like Bure, Bizona, and many others, have been en- eulphed by earthquakes.’ In another place, this learned geographer, in alluding to the tradition that Sicily had been separated by a convulsion from Italy, remarks, that at present the land near the sea in those parts was rarely shaken by earthquakes, since there were now open orifices whereby fire and ignited matters, and waters escape; but formerly, when the volcanos of Etna, the * © Quod enim hoc attollitur aut sub- sive quod inundatur ; potiiis tamen él sidit, et vel inundat queec dam loca, vel ab lis recedit, ejus rei causa non est, quod alia aliis sola humiliora sint aut 1 idem solum modo deprimitur : etiam modo attollitur modé deprimitur, mare: itaque redit locum, Poste: r ods vel exundat vel in suum ‘Restat, ut causam 8 Aine an salo, sive quod mari subest quod mari sube Toe enim multo est mobilius, et aa ob oe cele- riis multari , Geog. Edit. Almelov. Amst. star "Ub, Fs Volcanic eruptions, eruptiones fla- Leis in ine Lang translations, an ndin OTe, gaseous ossit.’ , avapuon, eruptions ? or zn epee of tana 2—Ihnd. p- 9 Cu. IT.] KNOWLEDGE OF THE ANCIENTS. 2D Lipari Islands, Ischia, and others, were closed up, the impri- soned fire and wind might have produced far more vehement movements.* The doctrine, therefore, that volcanos are safety-valves, and that the subterranean convulsions are pro- bably most violent when first the voleanic energy shifts itself to a new quarter, is not modern. We learn from a passage in Strabo,t that it was a dogma of the Gaulish Druids that the universe was immortal, but destined to survive catastrophes both of fire and water. That this doctrine was communicated to them from the Hast, with much of their learning, cannot be doubted. Czesar, it will be remembered, says that they made use of Greek letters in arithmetical computations. { Pliny.—This philosopher had no theoretical opinions of his own concerning changes of the earth’s surface; and in this department, as in others, he restricted himself to the task of a compiler, without reasoning on the facts stated by him, or attempting to digest them into regular order. But his enu- meration of the new islands which had been formed in the Mediterranean, and of other convulsions, shows that the ancients had not been inattentive observers of the changes which had taken place within the memory of man. Such, then, appear to have been the opinions entertained before the Christian era, concerning the past revolutions of our globe. Although no particular investigations had been made for the express purpose of interpreting the monuments of ancient changes, they were too obvious to be entirely dis- regarded; and the observation of the present course of nature presented too many proofs of alterations continually in progress on the earth to allow philosophers to believe that nature was in a state of rest, or that the surface had remained, and would continue to remain unaltered. But they had never compared attentively the results of the destroying and reproductive operations of modern times with those of remote eras, nor had they ever entertained so ‘much as a conjecture concerning the comparative antiquity of the human race, or of living species of animals and plants, with those belonging * Strabo, lib. vi. p. 396. + Book iv. t L. vi. ch. xill. 26 KNOWLEDGE OF THE ANCIENTS. [Cu. 11, to former conditions of the organic world. They had studieg the movements and positions of the heavenly bodies with laborious industry, and made some progress in investigating the animal, vegetable, and mineral kingdoms; but the an- cient history of the globe was to them a sealed book, and, although written in characters of the most striking and im- posing kind, they were unconscious even of its existence. CHAPTER ITI. HISTORY OF THE PROGRESS OF GEOLOGY—continued. ARABIAN WRITERS OF THE TENTH CENTURY—AVI ‘ENNA—-OMAR—COSMOGONY OF THE KORAN—KAZWINI—EARLY ITALIAN WRITERS—LEONARDO DA VINCI— FRACASTORO— CONTROVERSY AS TO THE REAL NATURE OF FOSSILS—ATTRI- BUTED TO THE MOSAIC DELUGE—PALISS\ —STENO—SCILLA QUIRINI—BOYLE —LISTER—LEIBNITZ—HOOKE 8 THEORY OF ELEVATION BY EARTHQUAKES— OF LOST SPECIES OF ANIMALS—RAY THEOLOGICAL WRITERS—WOOD- WARD'S DILUVIAL THEORY — BURNET — WHISTON — VALLISNERI — LAZZARO MORO—GENERELLI—BUFFON—HIS THEORY CONDEMNED BY THE SORBONNE AS UNORTHODOX — HIS DECLARATION — TARGIONI — ARDUINO — MICHELL — CATCOTT — RASPE — FUCHSEL — FORTIS — TESTA — WHITEHURST — PALLAS— SAUSSURE. ARABIAN wriTeERs.—After the decline of the Roman empire, the cultivation of physical science was first revived with some success by the Saracens, about the middle of the eighth cen- tury of ourera. The works of the most eminent classic writers were purchased at great expense from the Christians, and translated into Arabic; and Al Mamin, son of the famous Ha- rin-al-Rashid, the contemporary of Charlemagne, received with marks of distinction, at his court at Bagdad, astronomers and men of learning from different countries. This caliph, and some of his successors, encountered much opposition and jealousy from the doctors of the Mahometan law, who wished the Moslems to confine their studies to the Koran, dread- ing the effects of the diffusion of a taste for the physical sciences.* Avicenna.—Almost all the works of the early Arabian writers are lost. Amongst those of the tenth century, of which fragments are now extant, is a short treatise, ‘On the Forma- tion and Classification of Minerals,’ by Avicenna, a physician, * Mod, Univ. Hist. vol. ii, chap. iv. section iii. 28 OMAR.—THE KORAN, (Cx, Iq, in whose arrangement there is considerable merit. Tho second chapter, ‘ On the Cause of Mountains,’ is remarkable ; for mountains, he says, are formed, some by essential, otherg by accidental causes. In illustration of the essential, he jn- stances ‘a violent earthquake, by which land is elevated, and becomes a mountain;’ of the accidental, the principal, he says, is excavation by water, whereby cavities are produced, and adjoining lands made to stand out and form eminences.* Omar—Cosmogony of the Koran.—In the same century also, Omar, surnamed ‘ Hl Aalem,’ or ‘The Learned,’ wrote a work on ‘The Retreat of the Sea.? It appears that on comparing the charts of his own time with those made by the Indian and Persian astronomers two thousand years before, he had satisfied himself that important changes had taken place since the times of history in the form of the coasts of Asia, and that the extension of the sea had been greater at some former periods. He was confirmed in this opinion by the numerous salt springs and marshes in the interior of Asia,—a phenomenon from which Pallas, in more recent times, has drawn the same inference. Von Hoff has suggested, with great probability, that the changes in the level of the Caspian (some of which there is reason to believe have happened within the historical era), and the geological appearances in that district, indicating the desertion by that sea of its ancient bed, had probably led Omar to his theory of a general subsidence. But whatever may have been the proofs relied on, his system was declared contradictory to certain passages in the Koran, and he was called upon publicly to recant his errors; to avoid which per- secution he went into voluntary banishment from Samar- kand.t * ‘Montes quandéque fiunt ex causa chichte 1¢ theil, s. 234.—The Arabian essentiali, quanddque ex causa ac- persecutions for heretical dogmas m cidentali. Ex essentiali causa, ut ex theology wer bai sanguinary: vehementi motu terre elevatur terra, In the same aa fe erein learning was et fit mons. Accidentali, &c.—De Con- most in esteem, the Mahometans were gelatione Lapidum, ed. Gedani, 1682. divided into two sects, one of whom + Von Hoff, Geschichte dar Veriin- maintained that the Koran was increate derungen der Erdoberfliche, vol. i. p. and ees beat in the very essence 406, who cites Delisle, bey Hismann of God from all eternity ; and the other, Welt-und Volkergeschichte. Alte Ges- the Métazaliven who, admitting that the o- SF Ler ae ys Cu. II.] ARABIAN WRITERS,—KAZWINI. 29 The cosmological opinions expressed in the Koran are few, and merely introduced incidentally: so that it is not easy to understand how they could have interfered so seriously with free discussion on the former changes of the globe. The Prophet declares that the earth was created in two days, and the mountains were then placed on it; and during these, and two additional days, the inhabitants of the earth were formed ; and in two more the seven heavens.* There is no more detail of circumstances; and the deluge, which is also mentioned, is discussed with equal brevity. The waters are represented to have poured out of an oven; a strange fable, daid to be borrowed from the Persian Magi, who represented them as issuing from the oven of an old woman. All men were drowned, save Noah and his family; and then God said, ‘O earth, swallow up thy waters; and thou, O heaven, with- hold thy rain ;’ and immediately the waters abated.t We may suppose Omar to have represented the desertion of the land by the sea to have been gradual, and that his hypothesis required a greater lapse of ages than was con- sistent with Moslem orthodoxy; for it is to be inferred from the Koran, that man and this planet were created at the same time; and although Mahomet did not limit expressly the antiquity of the human race, yet he gave an implied sanction to the Mosaic chronology, by the veneration ex- pressed by him for the Hebrew Patriarchs.§ A manuscript work, entitled the ‘ Wonders of Nature,’ is preserved in the Royal Library at Paris, by an Arabian writer, Mohammed Kazwini, who flourished in the seventh century of the Hegira, or at the close of the thirteenth century of our era.|| Besides several curious remarks on aerolites, Koran was instituted by God, con- ceived it to have been first made when revealed to the Prophet at Mecca, and different caliphs in succession, and the followers of each sometimes submitted to be beheaded, or flogged till at the point of death, rather than renounce their creed.—Mod. Univ. Hist. vol. u. ch. iy. . * Koran, chap. xli. t Sale’s Koran, chap. xi. see note. t Ibid. § Kossa, appointed master to the Ca- Univ. Hist. vol. ii, ch. iv. || Translated by MM. Chezy and De Sacy, and cited by M. Elie de Beaumont, Ann. des Sci. Nat. 1832, 30 EARLY ITALIAN WRITERS. [Cx IT earthquakes, and the successive changes of position which the land and sea have undergone, we meet with the following beautiful passage which is given as the narrative of Kidhz, an allegorical personage:—‘I passed one day by a very ancient and wonderfully populous city, and asked one of ity inhabitants how long it had been founded. “It ig indeeg a mighty city,” replied he; ‘we know not how long it has existed, and our ancestors were on this subject as ignorant as ourselves.” Five centuries afterwards, as I passed by the same place, I could not perceive the slightest vestige of the city. I demanded of a peasant, who was gathering herbs upon its former site, how long it had been destroyed. “In sooth a strange question!” replied he. ‘The ground here has never been different from what you now behold it.”— “Was there not of old,” said I, “a splendid city here? ”— ‘““Never,” answered he, “‘ so far as we have seen, and never did our fathers speak to us of any such.” On my return there 500 years afterwards, I found the sea wm the same place, and on its shores were a party of fishermen, of whom I enquired how long the land had been covered by the waters? “Is this a question,” said they, “for a man like you? this spot has always been what it is now.” I again returned, 500 years afterwards, and the sea had disappeared; I enquired of a man who stood alone upon the spot, how long ago this change had taken place, and he gave me the same answer as I had received before. Lastly, on coming back again after an equal lapse of time, I found there a flourishing city, more populous and more rich in beautiful buildings, than the city I had seen the first time, and when I would fain have informed myself concerning its origin, the im habitants answered me, “Its rise is lost in remote antiquity: we are ignorant how long it has existed, and our fathers were on this subject as ignorant as ourselves.” ’ Early Italian Writers.—It was not till the earlier part of the sixteenth century that geological phenomena began to attract the attention of the Christian nations. At that period a very animated controversy sprang up in Italy, concerning the in nature and origin of marine shells, and other organised fossils, found abundantly in the strata of the peninsula. The cele- Cu. IIT] LEONARDO DA VINCI. dl brated painter Leonardo da Vinci, who in his youth had planned and executed some navigable canals in the north of Italy, was one of the first who applied sound reasoning to these subjects. The mud of rivers, he said, had covered and penetrated into the interior of fossil shells at a time when these were still at the bottom of the sea near the coast. ‘They tell us that these shells were formed in the hills by the influence of the stars; but I ask where in the hills are the stars now forming shells of distinct ages and species ? and how can the stars explain the origin of eravel, occurring at different heights and composed of pebbles rounded as if by the motion of running water ; or in what manner can such a cause account for the petrifaction in the same places of various leaves, sea-weeds, and marine crabs ? an The excavations made in 1517, for repairing the city of Verona, brought to light a multitude of curious petrifactions, and furnished matter for speculation to different authors, and among the rest to Fracastoro,t who declared his opinion, that fossil shells had all belonged to living animals, which had formerly lived and multiplied where their exuvic are now found. He exposed the absurdity of having recourse to the ‘ plastic force’ of Theophrastus (see above, p. 20) which had power to fashion stones into organic forms; and with no less cogent arguments, demonstrated the futility of attributing the situation of the shells in question to the Mosaic deluge, a theory obstinately defended by some. That inundation, he observed, was too transient; it consisted principally of fluviatile waters; and if it had transported shells to great distances, must have strewed them over the surface, not buried them at vast depths in the interior of mountains. His clear exposition of the evidence would have - terminated the discussion for ever, if the passions of mankind had not been enlisted in the dispute ; and even though doubts should for a time have remained in some minds, they would * See Venturi’s extracts from Da + Museum Calceol.— See Brocchi’s Vinci's MSS. now in Library of Insti- Discourse on the Progress of the Study tute of France. They are not mentioned of Fossil Conchology in Italy, where by Brocchi, and my attention was first some of the following notices on Italian ealled to them by Mr. Hallam. L.da writers will be found more at large. Vinci died a.p. 89 EARLY ITALIAN WRITERS.—FRACASTORO. (Cx. IIT speedily have been removed by the fresh information obtained almost immediately afterwards, respecting the structure of fossil remains, and of their living analogues. But the clear and philosophical views of Fracastoro were disregarded, and the talent and the argumentative powers of the learned were doomed for three centuries to be wasted in the discussion of these two simple and preliminary questions ; first, whether fossil remains had ever belonged to living creatures; and, secondly, whether, if this be admitted, all the phenomena could not be explained by the deluge of Noah. It had been the general belief of the Christian world down to the period now under consideration, that the origin of this planet was not more remote than a few thousand years ; and that since the creation the deluge was the only ereat catastrophe by which considerable change had been wrought on the earth’s surface. On the other hand, the opinion was scarcely less general, that the final dissolution of our system was an event to be looked for at no distant period. The era, it is true, of the expected millennium had passed away; and for five hundred years after the fatal hour when the annihilation of the planet had been looked for, the monks remained in undisturbed enjoyment of rich grants of land bequeathed to them by pious donors, who, in the pre- amble of deeds ‘beginning ‘appropinquante mundi termino’ ——‘ appropinquante magno judicii die,’ left lasting monu- ments of the popular delusion.* But although in the sixteenth century it had become necessary to interpret certain prophecies respecting the mil- lennium more liberally, and to assign a more distant date to the future conflagration of the world, we find, in the speculations of the early geologists, perpetual allusion to such an approaching catastrophe ; while in all that regarded the antiquity of the earth, no modification whatever of the opinions of the dark ages had been effected. Considerable alarm was at first excited when the attempt was made to invalidate, by physical proofs, an article of faith so generally about the period when the good King Roger was expelling the Saracens from * In Sicily, in particular, the title- deeds of many valuable grants of land f to the monasteries are headed by such that island, preambles, composed by the testators Cu. III. EARLY ITALIAN WRITERS. 933 received; but there was sufficient spirit of toleration and candour amongst the Italian ecclesiastics, to allow the sub- ject to be canvassed with much freedom. They even entered warmly into the controversy themselves, often favouring dif- ferent sides of the question; and however much we may deplore the loss of time and labour devoted to the defence of untenable positions, it must be conceded that they dis- played far less polemic bitterness than certain writers who followed them, ‘beyond the Alps,’ two centuries and a half later. CONTROVERSY AS TO THE REAL NATURE OF FOSSIL ORGANIC REMAINS. Mattioli—Falloppio.—The system of scholastic disputa- tions, encouraged in the universities of the middle ages, had unfortunately trained men to habits of indefinite argu- mentation; and they often preferred absurd and extrava- gant propositions, because greater skill was required to maintain them; the end and object of these intellectual combats being victory, and not truth. No theory could be so far-fetched or fantastical as not to attract some fol- lowers, provided it fell in with popular notions; and as cosmogonists were not at all restricted, in building their systems, to the agency of known causes, the opponents of Fracastoro met his arguments by feigning imaginary causes, which differed from each other rather in name than in sub- stance. Andrew Mattioli, for instance, an eminent botanist, the illustrator of Dioscorides, embraced the notion of Agricola, a skilful German miner, that a certain ‘materia pinguis,’ or ‘fatty matter,’ set into fermentation by heat, gave birth to fossil organic shapes. Yet Mattioli had come to the conclu- sion, from his own observations, that porous bodies, such as bones and shells, might be converted into stone, as being permeable to what he termed the ‘lapidifying juice.’ In like manner, Falloppio of Padua conceived that petrified shells were generated by fermentation in the spots where they are found, or that they had in some cases acquired their form from ‘the tumultuous movements of terrestrial exhalations.’ Although celebrated as a professor of anatomy, he taught VOL. I. D 84 EARLY ITALIAN WRITERS. (Cu. IT that certain tusks of elephants, dug up in his time in Apulia, were mere earthy concretions; and, consistently with these principles, he even went so far as to consider it probable, that the vases of Monte Testaceo at Rome were natural im- pressions stamped in the soil.* In the same spirit, Mercati, who published, in 1574, faithful figures of the fossil shells preserved by Pope Sixtus V. in the Museum of the Vatican, expressed an opinion that they were mere.stones, which had assumed their peculiar configuration from the influence of the heavenly bodies: and Olivi of Cremona, who described the fossil remains of a rich museum at Verona, was satisfied with considering them as mere ‘ sports of nature.’ Some of the fanciful notions of those times were deemed less unreasonable, as being somewhat in harmony with the Aristotelian theory of spontaneous generation, then taught in all the schools.t For men who had been taught in early youth, that a large proportion of living animals and plants was formed from the fortuitous concourse of atoms, or had sprung from the corruption of organic matter, might easily persuade themselves, that organic shapes, often imperfectly preserved in the interior of solid rocks, owed their existence to causes equally obscure and mysterious. Cardano, 1552.—But there were not wanting some who, during the progress of this century, expressed more sound and sober opinions. The title of a work of Cardano’s, published in 1552, ‘De Subtilitate’ (corresponding to what would now be called Transcendental Philosophy), would lead us to expect, in the chapter on minerals, many far-fetched theories character- istic of that age; but when treating of petrified shells, he decided that they clearly indicated the former sojourn of the sea upon the mountains. Cesalpino—Majoli, 1597.—Cesalpino, a celebrated botanist, conceived that fossil shells had been left on the land by the retiring sea,and had concreted into stone during the consolida- tion of the soil; § and in the following year (1597), Simeone Majoli || went still farther; and, coinciding for the most * De Fossilib. pp. 109 and 176. Progressi dello studio, vol. i. p. 5. + Aristotle, On Animals, chapters 1. § De Metallicis. and 16. || Dies Caniculares. { Brocchi, Con. Fos. Subap. Disc. sut Cu. IT.) PALISSY.—FABIO COLONNA. 35 part with the views of Cesalpino, suggested that the shells and submarine matter of the Veronese, and other districts, might have been cast up upon the land by volcanic ex- plosions, like those which gave rise, in 1538, to Monte Nuovo, near Puzzuoli. This hint seems to have been the first imperfect attempt to connect the position of fossil shells with the agency of volcanos, a system afterwards more fully developed by Hooke, Lazzaro Moro, Hutton, and other writers. Two years afterwards, Imperati advocated the animal origin of fossil shells, yet admitted that stones could vegetate by force of ‘an internal principle;’ and, as evidence of this, he referred to the teeth of fish and spines of echini found petrified.* Palissy, 1580.—Palissy, a French writer on ‘The Origin of Springs from Rain-water,’ and of other scientific works, under- took, in 1580, to combat the notions of many of his contem- poraries in Italy, that petrified shells had all been deposited by the universal deluge. ‘ He was the first,’ said Fontenelle, when, in the French Academy, he pronounced his eulogy, nearly a century and a half later, ‘who dared assert,’ in Paris, that fossil remains of testacea and fish had once belonged to marine animals. Fabio Colonna.—To enumerate the multitude of Italian writers, who advanced various hypotheses, all equally fantas- tical, in the early part of the seventeenth century, would be un- profitably tedious; but Fabio Colonna deserves to be distin- guished ; for, although he gave way to the dogma, that all fossil remains were to be referred to the deluge of Noah, he resisted the absurd theory of Stelluti, who taught that fossil wood and ammonites were mere clay, altered into such forms by sulphureous waters and subterranean heat ; and he pointed out the different states of shells buried in the strata, distin- guishing between, first, the mere mould or impression; secondly, the cast or nucleus; and, thirdly, the remains of the shell itself. He had also the merit of being the first to point out, that some of the fossils had belonged to marine and some to terrestrial testacea.+ * Storia Naturale. { Osserv. sugli Animali aquat. e terrest. 1626. D2 836 THEORY OF STENO. [Cx. If. Steno, 1669.—But the most remarkable work of that period was published by Steno, a Dane, once professor of anatomy at Padua, and who afterwards resided many years at the court of the Grand Duke of Tuscany. His treatise bears the quaint title of ‘ De Solido intra Solidum naturaliter contento (1669),’ by which the author intended to express, ‘On Gems, Crystals, and organic Petrifactions inclosed within solid Rocks.’ This work attests the priority of the Italian school in geological research; exemplifying at the same time the powerful ob- stacles opposed, in that age, to the general reception of enlarged views in the science. It was still a favourite dogma, that the fossil remains of shells and marine creatures were not of animal origin; an opinion adhered to by many from their extreme reluctance to believe, that the earth could have been inhabited by living beings before a great part of the existing mountains were formed. In reference to this controversy, Steno had dissected a shark recently taken from the Mediterranean, and had demonstrated that its teeth and bones were identical with many fossils found in Tuscany. He had also compared the shells discovered in the Italian strata with living species, pointed out their resemblance, and traced the various gradations from shells merely calcined, or which had only lost their animal gluten, to those petrifac- tions in which there was a perfect substitution of stony matter. Tn his division of mineral masses, he insisted on the secondary origin of those deposits in which the spoils of animals or fragments of older rocks were inclosed. He distinguished between marine formations and those of a fluviatile character, the last containing reeds, grasses, or the trunks and branches of trees. He argued in favour of the original horizontality of sedimentary deposits, attributing their present inclined and vertical position sometimes to the escape of subterranean vapours heaving the crust of the earth from below upwards, and sometimes to the falling in of masses overlying subter- ranean cavities. He declared that he had obtained proof that Tuscany must successively have acquired six distinct configurations, having been twice covered by water, twice laid dry with a level, Cu. ITT. } STENO.—SCILLA. 37 and twice with an irregular and uneven surface.* He dis- played great anxiety to reconcile his new views with Scrip- ture, for which purpose he pointed to certain rocks as having been formed before the existence of animals and plants: selecting unfortunately as examples certain forma- tions of limestone and sandstone in his adopted country, now known to contain, though sparingly, the remains of animals and plants,—strata which do not even rank as the oldest part of our secondary series. Steno suggested that Moses, when speaking of the loftiest mountains as having been covered by the deluge, meant merely the loftiest of the hills then existing, which may not have been very high. The diluvial waters, he supposed, may have issued from the interior of the earth into which they had retired, when in the beginning the land was separated from the sea. These, and other hypotheses on the same subject, are not calculated +o enhance the value of the treatise, and could scarcely fail to detract from the authority of those opinions which were sound and legitimate deductions from fact and observation. They have served, nevertheless, as the germs of many popular theories of later times, and in an expanded form have been put forth as original inventions by some of our contem- poraries. Scilla, 1670.—Scilla, a Sicilian painter, published in 1670, a treatise, in Latin, on the fossils of Calabria, illustrated by good engravings. This work proves the continued ascen- dancy of dogmas often refuted; for we find the wit and eloquence of the author chiefly directed against the obstinate incredulity of naturalists as to the organic nature of fossil shells.+ Like many eminent naturalists of his day, Scilla seems to give way to the popular persuasion, that all fossil shells were the effects and proofs of the Mosaic deluge. It may be doubted whether he was perfectly sincere, and some of his contemporaries who took the same course were certainly * «Sexitaque distinctas Etruriefacies — of Paniscus in relief:— ‘I believe,’ agnoscimus, dum i ida, bis plana, said the orator, ‘that the figure bore et sicca, bis aspera fuerit,’ &c. some resemblance to Paniscus, but not Scilla quotes the remark of Cicero such that you would have deemed it on the story that a stone in Chios had been cleft open, and presented the head sculptured by Scopas ; for chance never perfectly imitates the truth. 38 DILUVIAL THEORY. [Cu. Tif. not so. But so eager were they to root out what they justly considered an absurd prejudice respecting the nature of organised fossils, that they appear to have been ready to make any concessions, in order to establish this preliminary point. Such a compromising policy was short-sighted, since it was to little purpose that the nature of the documents should at length be correctly understood, if men were to be prevented from deducing fair conclusions from them. Diluvial Theory.—The theologians who now entered the field in Italy, Germany, France, and England, were innumerable ; and henceforward, they who refused to subscribe to the posi- tion, that all marine organic remains were proofs of the Mosaic deluge, were exposed to the imputation of disbelieving the whole of the sacred writings. Scarcely any step had been made in approximating to sound theories since the time of Fracas- toro, more than a hundred years having been lost, in writing down the dogma that organised fossils were mere sports of nature. Anadditional period of a century and a half was now destined to be consumed in exploding the hypothesis, that or- ganised fossils had all been buried in the solid strata by Noah’s flood. Never did a theoretical fallacy, in any branch of science, interfere more seriously with accurate observation and the systematic classification of facts. In recent times, we may attribute our rapid progress chiefly to the careful determina- tion of the order of succession in mineral masses, by means of their different organic contents, and their regular super- position. But the old diluvialists were induced by their system to confound all the groups of strata together instead of discriminating—to refer all appearances to one cause and to one brief period, not to a variety of causes acting through- out a long succession of epochs. They saw the phenomena only, as they desired to see them, sometimes misrepresenting facts, and at other times deducing false conclusions from correct data. Under the influence of such prejudices, three centuries were of as little avail as a few years in our own times, when we are no longer required to propel the vessel against the force of an adverse current. : It may be well, therefore, to forewarn the reader, that m tracing the history of geology from the close of the seventeenth Cu. IIT.) DILUVIAL THEORY.—-QUIRINI. 39 to the end of the eighteenth century, he must expect to be occupied with accounts of the retardation, as well as of the advance, of the science. It will be necessary to point out the frequent revival of exploded errors, and the relapse from sound to the most absurd opinions 5 and to dwell on futile reasoning and visionary hypothesis, because some of the most extravagant systems were invented or controverted by men of acknowledged talent. In short, a sketch of the progress of geology is the history of a constant and violent struggle of new opinions against doctrines sanctioned by the implicit faith of many generations, and supposed to rest on scriptural authority. The enquiry, therefore, although highly interest- ing to one who studies the philosophy of the human mind, ig too often barren of instruction to him who searches for truths in physical science. Quirini, 1676.—Quirini, in 1676,* contended, in opposition to Scilla, that the diluvial waters could not have conveyed heavy bodies to the summit of mountains, since the agitation of the sea never (as Boyle had demonstrated) extended to great depths ;+ and still less could the testacea, as some pretended, have lived in these diluvial waters ; for ‘thé duration of the flood was brief, and the heavy rains must have destroyed the salt- ness of the sea!’ He was the first writer who ventured to main- tain that the universality of the Mosaic cataclysm ought not to be insisted upon. As to the nature of petrified shells, he con- ceived that as earthy particles united in the sea to form the shells of mollusca, the same crystallising process might be effected on the land; and that, in the latter case, the germs of animals might have been disseminated through the substance of the rocks, and afterwards developed by virtue of humidity. Visionary as was this doctrine, it gained many proselytes Ky De Testaceis fossilibus Mus. Sep- wereno signs of agitation at the depth taliani. of fifteen fathoms; and that even during he opinions of Boyle, alluded to heavy gales of wind, the motion of the before, in a short article entitled ‘ On depth of twelve or fifteen feet. He had the Bottom of the Sea” From obser- also learnt from some of his informants, vations collected from the divers of the that there were currents running in pearl fishery, Boyle inferred that, when opposite directions at different depths. — the waves were six or seven feet high Boyle’s Works, vol. ii. p. 110. London, above the surface of the water, there 1744. 40 PLOT.—LISTER.—LEIBNITZ. (Cu. TI, even amongst the more sober reasoners of Ftaly and Germany ; for it conceded that the position of fossil bodies could not be accounted for by the diluvial theory. Plot—-Lister, 1678.—In the meantime, the doctrine that fossil shells had never belonged to real animals maintained itg ground in England, where the agitation of the question began at a much later period. Dr. Plot, in his ‘Natural History of Oxfordshire’ (1677), attributed to a ‘plastic virtue latent in the earth’ the origin of fossil shells and fishes; and Lister, to his accurate account of British shells, in 1678, added the fossil species, under the appellation of tarbinated and bivalve stones, ‘Hither,’ said he, ‘ these were terriginous, or, if otherwise, the animals they so exactly represent have become extinct.’ Thig writer appears to have been the first who was aware of the continuity over large districts of the principal groups of strata in the British series, and who proposed the construction of regular geological maps.* Leibnitz, 1680.—The great mat] tician Leibnitzpublished his ‘Protogeea’ in 1680. He imagined this planet to have been originally a burning luminous mass, which ever since its creation has been undergoing refrigeration. When the outer crust had cooled down sufficiently to allow the vapours to be condensed, they fell, and formed a universal ocean, covering the loftiest mountains, and investing the whole globe. The crust, as it consolidated from a state of fusion, assumed a vesicular and cavernous structure; and being rent in some places, allowed the water to rush into the subterranean hol- lows, whereby the level of the primeval ocean was lowered. The breaking in of these vast caverns is supposed to have given rise to the dislocated and deranged position of the strata ‘which Steno had described,’ and the same disrup- tions communicated violent movements to the incumbent waters, whence great inundations ensued. The waters, atter they had been thus agitated, deposited their sedimentary matter during intervals of quiescence, and hence the various stony and earthy strata. ‘We may recognise, therefore,’ says Leibnitz, ‘a double origin of primitive masses, the one by * See Conybeare and Phillips, ‘Outlines of the Geology of England and Wales,’ p. 12. Cu. III.] HOOKE. 41 refrigeration from igneous fusion, the other by concretion from aqueous solution.’ * By the repetition of similar causes (the disruption of the crust and consequent floods), alterna- tions of new strata were produced until at length these causes were reduced to a condition of quiescent equilibrium, and a more permanent state of things was established.+ Hooke, 1668.—The ‘ Posthumous Works of Robert Hooke, M.D.,’ well known as a great mathematician and natural phi- losopher, appeared in 1705, containing ‘A Discourse on Harth- quakes,’ which, we are informed by his editor, was written in 1688, but revised at subsequent periods.t Hooke frequently refers to the best Italian and English authors who wrote before his time on geological subjects; but there are no pas- sages in his works implying that he participated in the en- larged views of Steno and Lister, or of his contemporary, Woodward, in regard to the geographical extent of certain groups of strata. His treatise, however, is the most philoso- phical production of that age, in regard to the causes of former changes in the organic and inorganic kingdoms of nature. ‘However trivial a thing,’ he says, ‘a rotten shell may appear to some, yet these monuments of nature are more certain tokens of antiquity than coins or medals, since the best of those may be counterfeited or made by art and design, as may also books, manuscripts, and inscriptions, as all the learned are now sufficiently satisfied has often been actually practised,’ &c.; ‘and though it must be. granted that it is very difficult to read them (the records of nature) and to ravse a chronology out of them, and to state the intervals of the time wherein such or such catastrophes and mutations have happened, yet it is not impossible.’ § * ‘Unde jam duplex origo intelligitur Mr. Conybeare’s Report to the Brit. primorum corporum, una, cum a ignis Assoc. on the Progress of Geological fusione refrigescerent, altera, cum re- Science, 1832. =) > subinde alia aliis imponerentur, et facies teneri adhue orbis sepius novata est. status.— For an a I views of Leibnitz, in his Protogcea, see ¢ Between the year 1688 and his death, in 1703, he read several memoirs to the Royal Society, and delivered lec- tures on various subjects, relating to fossil remains and the effects of earth- quakes. § Posth. Works, Lecture, Feb. 29, 1688. 42 HOOKE. [Cu. Iq, Respecting the extinction of species, Hooke was aware that the fossil ammonites, nautili, and many other shells and fosgi] skeletons found in England, were of different species from any then known; but he doubted whether the species had become extinct, observing that the knowledge of naturalists of all the marine species, especially those inhabiting the deep sea, wag very deficient. In some parts of his writings, however, he leans to the opinion that species had been lost; and in speculating on this subject, he even suggests that there might be some connection between the disappearance of certain kinds of animals and plants, and the changes wrought by earthquakes in former ages. Some species, he observes, with ereat sagacity, are ‘ peculiar to certain places, and not to be found elsewhere. If, then, such a place had been swallowed up, it is not improbable but that those animate beings may have been destroyed with it; and this may be true both of aérial and aquatic animals: for those animated bodies, whether vegetables or animals, which were naturally nourished or refreshed by the air, would be destroyed by the water,’ &c.* Turtles, he adds, and such large ammonites as are found in Portland, seem to have been the productions of hotter countries; and it is necessary to suppose that England once lay under the sea within the torrid zone! To explain this and similar phe- nomena, he indulges in a variety of speculations concerning changes in the position of the axis of the earth’s rotation, ‘ shifting of the earth’s centre of gravity, analogous to the revolutions of the magnetic pole,’ &c. None of these conjec- tures, however, are proposed dogmatically, but rather in the hope of promoting fresh enquiries and experiments In opposition to the prejudices of his age, we find him arguing against the idea that nature had formed fossil bodies ‘for no other end than to play the mimic in the mineral kingdom ; ’—maintaining that figured stones were ‘ really the several bodies they represent, or the mouldings of them petrified,’ and ‘ not as some have imagined, “a lusus nature,” sporting herself in the needless formation of useless beings. t * Posth. Works, p. 32 é able clearness, the different eee + Posth. Works, Leet Feb. 15 wherein organic substances may beco oa 1688. Hooke explained, mn RES lapidjfied ; and, among other ao BS = if & = op SAR HOOKE ON EXTINCT SPECIES, 43 Cu, I1.] It was objected to Hooke, that his doctrine of the extinction of species derogated from the wisdom and power of the Omni- potent Creator; but he answered, that, as individuals die, there may be some termination to the duration of a species ; and his opinions, he declared, were not repugnant to Holy Writ: for the Scriptures taught that our system was degene- rating, and tending to its final dissolution ; ‘and as, when that shall happen, all the species will be lost, why not some at one time and some at another ?’ * But his principal object was to account for the manner in which shells had been conveyed into the higher parts of ‘ the Alps, Apennines, and Pyrenean hills, and the interior of conti- nents in general.’ These and other appearances, he said, might have been brought about by earthquakes, ‘ which have turned plains into mountains, and mountains into plains, seas into land, and land into seas, made rivers where there were none before, and swallowed up others that formerly were, &e. &e.; and which, since the creation of the world, have wrought many changes on the superficial parts of the earth, and have been the instruments of placing shells, bones, plants, fishes, and the like, in those places where, with much astonishment, we find them.’ + This doctrine, it is true, had been laid down in terms almost equally explicit by Strabo, to explain the occurrence of fossil shells in the interior of conti- nents, and to that geographer, and other writers of antiquity, Hooke frequently refers; but the revival and development of the system was an important step in the progress of modern science. Hooke enumerated all the examples known to him of ecified wood of the Irawadi should have i than one hun- tions, he mentions some silicified palm- wood brought from Africa, on which M. dela Hire had read a memoir to the Royal Academy of France (June, 1692), wherein he had pointed out, not only the tubes running the length of the trunk, but the roots at one extremity. De la fossil animals and vegetables, by Mr. Crawfurd and Dr. Wallich.—See Geol. Trans. vol. ii. part iii. p. 377, second series. De la Hire cites Father Duchatz, in the second volume of ‘‘ Observations leagues the virtue of petrifying wood It is an interesting fact that the sili- made in the Indies by the Jesuits.” x Posth. Works, Lecture, May 29, 1689. {+ Posth. Works, p. 312. 44 HOOKE’S DILUVIAL THEORY. [Cu Ty, subterranean disturbance, from ‘ the sad catastrophe of Sodom and Gomorrah,’ down to the Chilian earthquake of 1646. The elevating of the bottom of the sea, the sinking and gub. mersion of the land, and most of the inequalities of the earth’s surface, might, he said, be accounted for by the agency of these subterranean causes. He mentions that the coast neay Naples was raised during the eruption of Monte Nuovo; and that, in 1591, land rose in the island of St. Michael, during an eruption: and although it would be more difficult, he says, to prove, he does not doubt but that there had been as many earthquakes in the parts of the earth under the ocean, as in the parts of the dry land; in confirmation of which, he mentions the immeasurable depth of the sea near some volcanos. To attest the extent of simultaneous subterranean movements, he refers to an earthquake in the West Indies, in the year 1690, where the space of earth raised, or ‘ struck upwards,’ by the shock, exceeded, he affirms, the length of the Alps and Pyrenees. Hooke’s dilwvial theory.x—As Hooke declared the favourite hypothesis of the day, ‘ that marine fossil bodies were to be referred to Noah’s flood,’ to be wholly untenable, he appears to have felt himself called upon to substitute a diluvial theory of his own, and thus he became involved in countless diffi- culties and contradictions. ‘ During the great catastrophe,’ he said, ‘ there might have been a changing of that part which was before dry land into sea by sinking, and of that which was sea into dry land by raising, and marine bodies might have been buried in sediment beneath the ocean, in the interval between the creation and the deluge.’ * Then follows a disquisition on the separation of the land from the waters, mentioned in Genesis ; during which operation some places of the shell of the earth were forced outwards, and others pressed downwards or inwards, &c. His diluvial hypothesis very much resembled that of Steno, and was entirely op- posed to the fundamental principles professed by him, that he would explain the former changes of the earth in a more natural manner than others had done. When, in despite of this declaration, he required a former ‘crisis of nature,’ and * Posth. Works, p. 410. Cu. III.] RAY. 45 taught that earthquakes had become debilitated, and that the Alps, Andes, and other chains, had been lifted up in a few months, he was compelled to assume so rapid a rate of change, that his machinery appeared scarcely less extravagant than that of his most fanciful predecessors. For this reason, perhaps, his whole theory of earthquakes met with undeserved neglect. Ray, 1692.—One of his contemporaries, the celebrated naturalist, Ray, participated in the same desire to explain geological phenomena by reference to causes less hypothetical than those usually resorted to.* In his essay on ‘ Chaos and Creation,’ he proposed a system, agreeing in its outline, and in many of its details, with that of Hooke; but his knowledge of natural history enabled him to elucidate the subject with yarious original observations. Harthquakes, he suggested, might have been the second causes employed at the creation, in separating the land from the waters, and in gathering the waters together into one place. He mentions, like Hooke, the earthquake of 1646, which had violently shaken the Andes for some hundreds of leagues, and made many alterations therein. In assigning a cause for the general deluge, he preferred a change in the earth’s centre of gravity to the introduction of earthquakes. Some unknown cause, he said, might have forced the subterranean waters outwards, as was, perhaps, indicated by ‘the breaking up of the fountains of the great deep.’ Ray was one of the first of our writers who enlarged upon the effects of running water upon the land, and of the en- croachment of the sea upon the shores. So important did he consider the agency of these causes, that he saw in them an indication of the tendency of our system to its final disso- lution ; and he wondered why the earth did not proceed more rapidly towards a general submersion beneath the sea, when so much matter was carried down by rivers, or undermined in the sea-cliffs. We perceive clearly from his writings, that the gradual decline of our system, and its future consummation * Ray’s Physico-theological Dis- his learning and deep insight into the courses were of somewhat later date mysteries of nature he deservedly ho- than Hooke’s great work on earthquakes. noured.— On the Deluge, chap. iv. He speaks of Hooke as one ‘ whom for 46 RAY.—WOODWARD, (Cu, TI by fire, was held to be as necessary an article of faith by the orthodox, as was the recent origin of our planet. Hig discourses, like those of Hooke, are highly interesting, ag attesting the familiar association in the minds of philosophers, in the age of Newton, of questions in physics and divinity, Ray gave an unequivocal proof of the sincerity of his mind, by sacrificing his preferment in the Church, rather than take an oath against the Covenanters, which he could not reconcile with his conscience. His reputation, moreover, in the gcien- tific world placed him high above the temptation of courting popularity, by pandering to the physico-theological taste of his age. It is, therefore, curious to meet with so many cita- tions from the Christian fathers and prophets in his essays on physical science—to find him in one page proceeding, by the strict rules of induction, to explain the former changes of the globe, and in the next gravely entertaining the question, whether the sun and stars, and the whole heavens, shall be annihilated, together with the earth, at the era of the grand conflagration. Woodward, 1695.—Among the contemporaries of Hooke and Ray, Woodward, a professor of medicine, had acquired the most extensive information respecting the geological structure of the crust of the earth. He had examined many parts of the British strata with minute attention; and his systematic collection of specimens, bequeathed to the Uni- versity of Cambridge, and still preserved there as arranged by him, shows how far he had advanced in ascertaining the order of superposition. From the great number of facts col- lected by him, we might have expected his theoretical views to be more sound and enlarged than those of his contempo- raries; but in his anxiety to accommodate all observed phe- nomena to the scriptural account of the Creation and Deluge, he arrived at most erroneous results. He conceived ‘the whole terrestrial globe to have been taken to pieces and dis- solved at the flood, and the strata to have settled down from this promiscuous mass as any earthy sediment from a fluid.” In corroboration of these views he insisted upon the fact, that ‘marine bodies are lodged in the strata according to * Essay towards a Natural History of the Earth, 1695. Preface. Cu. IIT.] BURNET. 47 the order of their gravity, the heavier shells in stone, the lighter in chalk, and so of the rest.* Ray immediately ex- posed the unfounded nature of this assertion, remarking truly that fossil bodies ‘are often mingled, heavy with light, in the same stratum;’ and he even went 80 far as to say, that Woodward ‘must have invented the phenomena for the sake of confirming his bold and strange hypothesis ’+—a strong expression from the pen of a contemporary. Burnet, 1680-1690.—At the same time Burnet published his ‘ Theory of the Earth.’{ The title is most characteristic of the age,—‘ The Sacred Theory of the Harth ; containing an Account of the Original of the Earth, and of all the gene- ral Changes which it hath already undergone, or is to undergo, till the Consummation of all Things.’ Even Mil- ton had scarcely ventured in his poem to indulge his imagi- nation so freely in painting scenes of the Creation and Deluge, Paradise and Chaos. He explained why the primeval earth enjoyed a perpetual spring before the flood! showed how the crust of the globe was fissured by ‘ the sun’s rays,’ so that it burst, and thus the diluvial waters were let loose from a supposed central abyss. Not satisfied with these themes, he derived from the books of the inspired writers, and even from heathen authorities, prophetic views of the future revolutions of the globe, gave a most terrific descrip- tion of the general conflagration, and proved that a new heaven and a new earth will rise out of a second chaos—after which will follow the blessed millennium. The reader should be informed, that, according to the opi- nion of many respectable writers of that age, there was good scriptural ground for presuming that the garden bestowed upon our first parents was not on the earth itself, but above the clouds, in the middle region between our planet and the moon. Burnet approaches with becoming gravity the dis- cussion of so important a topic. He was willing to concede that the geographical position of Paradise was not in Mesopo- tamia, yet he maintained that it was upon the earth, and in * Essay towards a Natural History { First published in Latin between of the Earth, 1695. Preface. the years 1680 and 1690. + Consequences of the Deluge, p. 165. 48 BURNET.—WHISTON. [Cu. In. the southern hemisphere, near the equinoctial line. Butjoy selected this conceit as a fair mark for his satire, when, amongst the numerous accomplishments of Hudibras, he says,— “Te knew the seat of Paradise, Could tell in what degree it lies ; And, as he was disposed, could pr ove it Below the moon, or else above Yet the same monarch, who is said never to have slept without Butler’s poem under his pillow, was so great an admirer and patron of Burnet’s book, that he ordered it to be translated from the Latin into English. The style of the ‘Sacred Theory’ was eloquent, and the book displayed powers of invention of no ordinary stamp. It was, in fact, a fine historical romance, as Buffon afterwards declared: but it was treated as a work of profound science in the time of its author, and was panegyrized by Addison in a Latin ode, while Steele praised it in the ‘ Spectator.’ Whiston, 1696.—Another production of the same school, and equally characteristic of the time, was that of Whiston, entitled, ‘A New Theory of the Earth ; wherein the Creation of the World in Six Days, the Universal Deluge, and the General Conflagration, as laid down in the Holy Scriptures, are shown to be perfectly agreeable to Reason and Philo- sophy.’ He was at first a follower of Burnet; but his faith in the infallibility of that writer was shaken by the declared opinion of Newton, that there was every presumption in astronomy against any former change in the inclination of the earth’s axis. This was a leading dogma in Burnet’s system, though not original, for it was borrowed from an Italian, Alessandro degli Alessandri, who had suggested it in the beginning of the fifteenth century, to account for the former occupation of the present continents by the sea. La Place has since strengthened the arguments of Newton, against the probability of any former revolution of this kind. The remarkable comet of 1680 was fresh in the memory of every one when Whiston first began his cosmological studies; and the principal novelty of his speculations consisted in at- tributing the deluge to the near approach to the earth of one Cu, IIT.) HUTCHINSON.—CELSIUS.—SCHEUCHZER. 49 of these erratic bodies. Having ascribed an increase of the waters to this source, he adopted Woodward’s theory, sup- posing all stratified deposits to have resulted from the ‘chaotic sediment of the flood.2. Whiston was one of the first who ventured to propose that the text of Genesis should be interpreted differently from its ordinary acceptation, so that the doctrine of the earth having existed long previous to the creation of man might no longer be regarded as unortho- dox. He had the art to throw an air of plausibility over the most improbable parts of his theory, and seemed to be pro- ceeding in the most sober manner, and, by the aid of mathe- matical demonstration, to the establishment of his various propositions. Locke pronounced a panegyric on his theory, commending him for having explained so many wonderful and before inexplicable things. His book, as well as Bur- net’s, was attacked and refuted by Keill.* Like all who introduced purely hypothetical causes to account for natural phenomena, Whiston retarded the progress of truth, divert- ing men from the investigation of the laws of sublunary nature, and inducing them to waste time in speculations on the power of comets to drag the waters of the ocean over the land—on the condensation of the vapours of their tails into water, and other matters equally edifying. Hutchinson, 1724.—John Hutchinson, who had been em- ployed by Woodward in making his collection of fossils, published afterwards, in 1724, the first part of his ‘Moses’s Principia,’ wherein he ridiculed Woodward’s hypothesis. He and his numerous followers were accustomed to declaim loudly against human learning; and they maintained that the Hebrew Scriptures, when rightly translated, comprised a perfect system of natural philosophy, for which reason they objected to the Newtonian theory of gravitation. Celsiws.— Andrea Celsius, the Swedish astronomer, published about this time his remarks on the gradual diminution and sinking of the waters in the Baltic, to which I shall have oc- casion to advert more particularly in the sequel (Ch. XXXTI.). Scheuchzer, 1708.—In Germany, in the meantime, Scheuchzer published his ‘ Complaint and Vindication of the * An Examination of Dr. Burnet’s Theory, &c. 2d ed. 1734. VOL. I. E 50 ITALIAN GEOLOGISTS.—VALLISNERI. [Cx, Ir Fishes’ (1708), ‘Piscium Querele et Vindicie,’ a work of zoological merit, in which he gave some good plates and descriptions of fossil fish. Among other conclusions he laboured to prove that the earth had been remodelled at the deluge. Pluche, also, in 1732, wrote to the same effect, while Holbach, in 1753, after considering the various attempts to refer all the ancient formations to the flood of Noah, exposed the inadequacy of this cause. Italian Geologists—Vallisneri.—I return with pleasure to the geologists of Italy, who preceded, as has been already shown, the naturalists of other countries in their investiga- tions into the ancient history of the earth, and who still maintained a decided pre-eminence. They refuted and ridi- culed the physico-theological systems of Burnet, Whiston, and Woodward ;* while Vallisneri,t in his comments on the Woodwardian theory, remarked how much the interests of religion, as well as those of sound philosophy, had suffered by perpetually mixing up the sacred writings with questions in physical science. The works of this author were rich in original observations. He attempted the first general sketch of the marine deposits of Italy, their geographical extent, and most characteristic organic remains. In his treatise ‘On the Origin of Springs,’ he explained their dependence on the order, and often on the dislocations, of the strata, and reasoned philosophically against the opinions of those who regarded the disordered state of the earth’s crust as exhibit- ing signs of the wrath of God for the sins of man. He found himself under the necessity of contending, in his preliminary chapter, against St. Jerome, and four other principal inter- preters of Scripture, besides several professors of divinity, ‘that springs did not flow by subterranean siphons and cavi- ties from the sea upwards, losing their saltness in the passage,’ for this theory had been made to rest on the infallible testi- mony of Holy Writ. Although reluctant to generalise on the rich materials * Ramazzini even asserted, that the other correspondence between these sys- ms, except that both were equally from a dialogue of one Patrizio; but whimsical. ye : : : : ; Pee 5 Brocchi, after reading that dialogue, + Dei Corpi Marm, Lettere critiche, u assures us, that there was scarcely any &e. 1721. Cu. III.] LAZZARO MORO. 51 accumulated in his travels, Vallisneri had been so much struck with the remarkable continuity of the more recent marine strata, from one end of Italy to the other, that he came to the conclusion that the ocean formerly extended over the whole earth, and after abiding there for a long time, had gra- dually subsided. This opinion, however untenable, was a great step beyond Woodward's diluvian hypothesis, against ich Vallisneri, and after him all the Tuscan sercaces uniformly contended, while it was warmly supported by t members of the Institute of Bologna.* Among others of that day, Spada, a priest of Grezzana, in 1737, wrote to prove that the petrified marine bodies near Verona were not diluvian.+ Mattani drew a similar inference from the shells of Volterra and other places: while Costantini, on the other hand, whose observations on the valley of the Brenta and other districts were not without value, undertook to vindicate the truth of the deluge, as also to prove that Italy had been peopled by the descendants of Japhet.t Moro, 1740.—Lazzaro Moro, in his work (published in 1640) ‘On the Marine Bodies which are found in the Moun- tains,’§ attempted to apply the theory of earthquakes, and changes of level in the earth’s crust, as expounded by Strabo, Pliny, and other ancient authors, with whom he was familiar, to the geological phenomena described by Vallisneri. || His attention was awakened to the elevating power of subterra- nean forces by a remarkable phenomenon which happened in his own time, and which had also been noticed by Vallisner1 in his letters. A new island rose in 1707 from deep water in the Gulf of Santorin in the Mediterranean, during continued shocks of an earthquake, and, increasing rapidly in size, grew in less than a month to be half a mile in circumference, and about twenty-five feet above high-water mark. It was soon afterwards covered by volcanic ejections, but, when first of his views were in accordance Bis th t Ibid. p. 33. Pad he was probably ignorant of t i Ibid writings, for they had not been aoe § Sui Crostacei ed i Corpi Marini lated. Ashe always refers to the Latin che si trovano sui Mon edition of Burnet, and a French trans- ro does not va , the works of lation of Woodward, we may presume Tooke Dba Ray; and although so on. oe he did not read English. * Brocchi, p. 28. i 52 LAZZARO MORO. (Oa ie examined, it was found to be a white rock, bearing on jt surface living oysters and crustacea. In order to ridicule the various theories then in vogue, Moro ingeniously supposes the arrival on this new island of a party of naturalists igno- rant of its recent origin. One immediately points to the marine shells, as proofs of the universal deluge; another argues that they demonstrate the former residence of the sea upon the mountains; a third dismisses them as mere sports of nature; while a fourth affirms, that they were born and nou- rished within the rock in ancient caverns, into which salt water had been raised in the shape of vapour by the action of subterranean heat. Moro pointed with great judgment to the faults and dis- locations of the strata described by Vallisneri, in the Alps and other chains, in confirmation of his doctrine, that the continents had been heaved up by subterranean movements. He objected, on solid grounds, to the hypothesis of Burnet and of Woodward; yet he ventured so far to disregard the protest of Vallisneri, as to undertake the adaptation of every part of his own system to the Mosaic account of the creation. On the third day, he said, the globe was everywhere covered to the same depth by fresh water; and when it pleased the Supreme Being that the dry land should appear, volcanic explosions broke up the smooth and regular surface of the earth composed of primary rocks. These rose in mountain masses above the waves, and allowed melted metals and salts to ascend through fissures. The sea gradually acquired its saltness from volcanic exhalations, and, while it became more circumscribed in area, increased in depth. Sand and ashes ejected by volcanos were regularly disposed along the bottom of the ocean, and formed the secondary strata, which in their turn were lifted up by earthquakes. We need not follow this author in tracing the progress of the creation of vegetables and animals on the other days of creation ; but, upon the whole, it may be remarked, that few of the old cosmological theories had been conceived with so little violation of known analogies. Generelli’s illustrations of Moro, 1749.—The style of Moro was extremely prolix, and, like Hutton, who, at a later period, Cu. II.] GENERELII. 53 advanced many of the same views, he stood in need of an illustrator. The Scotch geologist was hardly more fortunate in the advocacy of Playfair, than was Moro in numbering amongst his admirers Cirillo Generelli, who, nine years afterwards, delivered at a sitting of Academicians at Cre- mona a spirited exposition of his theory. This learned Carmelitan friar does not pretend to have been an original observer, but he had studied sufficiently to enable him to confirm the opinions of Moro by arguments from other writers; and his selection of the doctrines then best estab- lished is so judicious, that a brief abstract of them cannot fail to be acceptable, as illustrating the state of geology in Burope, and in Italy in particular, before the middle of the last century. The bowels of the earth, says he, have carefully preserved the memorials of past events, and this truth the marine productions so frequent in the hills attest. From the reflec- tions of Lazzaro Moro; we may assure ourselves that these are the effects of earthquakes in past times, which have changed vast spaces of sea into terra firma, and inhabited lands into seas. In this, more than in any other department of physics, are observations and experiments indispensable, and we must diligently consider facts. The land is known, wherever we make excavations, to be composed of different strata or soils placed one above the other, some of sand, some of rock, some of chalk, others of marl, coal, pumice, gypsum, lime, and the rest. These ingredients are sometimes pure, and sometimes confusedly intermixed. Within are often imprisoned different marine fishes, like dried mummies, and more frequently shells, crustacea, corals, plants, &c., not only in Italy, but in France, Germany, England, Africa, Asia, and America;—sometimes in the lowest, sometimes in the loftiest beds of the earth, some upon the mountains, some in deep mines, others near the sea, and others hundreds of miles distant from it. Woodward conjectured that these marine bodies might be found everywhere; but there are rocks in which none of them occur, as is sufficiently attested by Vallisneri and Marsilli. The remains of fossil animals consist chiefly of their more solid parts, and the most rocky 5A GENERELLYS TREATISE ON (Cx. IT strata must have been soft when such exuviee were inclogeq in them. Vegetable productions are found in different states of maturity, indicating that they were imbedded in different seasons. Hlephants, elks, and other terrestrial quadrupeds, have been found in Hngland and elsewhere, in superficial strata, never covered by the sea. Alternations are rare, yet not without example, of marine strata, with those which con- tain marshy and terrestrial productions. Marine animals are arranged in the subterraneous beds with admirable order, in distinct groups, oysters here, dentalia or corals there, &c., as now, according to Marsilli,* on the shores of the Adriatic, We must abandon the doctrine, once so popular, which denies that organised fossils were derived from living beings, and we cannot account for their present position by the ancient theory of Strabo, nor by that of Leibnitz, nor by the universal deluge, as explained by Woodward and others: ‘nor is it reasonable to call the Deity capriciously upon the stage, and to make him work miracles for the sake of confirming our preconceived hypothesis.—‘I hold in utter abomination, most learned Academicians! those systems which are built with their foundations in the air, and cannot be propped up without a miracle; and I undertake, with the assistance of Moro, to explain to you how these marine animals were trans- ported into the mountains by natural causes.’+ A brief abstract then follows of Moro’s theory, by which, says Generelli, we may explain all the phenomena, as Vallis- neri so ardently desired, ‘without violence, without fictions, without hypothesis, without miracles.t The Carmelitan then proceeds to struggle against an obvious objection to Moro’s system, considered as a method of explaining the revolutions of the earth, naturally. If earthquakes have been the agents of such mighty changes, how does it happen that their effects since the times of history have been so inconsiderable ? This same difficulty had, as we have seen, presented itself to * Sagei o fisico intorno alla Storia del DY Crostacel e di altre Produz. del Mare, parti. p. 24. Me ae &e. 1749. t+ ‘ Abbomino al somno qualsivoglia t ‘Senza violenze, senza finzioni, sistema, che sia di planta fabbricato in suas supposti, senza miracoli.-—De’ a e. wiaj massime quando é tale, che non Crostacei e di altre Pde “tel Mare, possa sostenersi senza un miracolo,’ &e. &e. 1749 Cu. III.] LAZZARO MORO’S THEORY. 55 Hooke, half a century before, and forced him to resort to a former ‘crisis of nature :’ but Generelli defended his position by showing how numerous were the accounts of eruptions and earthquakes, of new islands, and of elevations and sub- sidences of land, and yet how much greater a number of like events mnst have been unattested and unrecorded during the last six thousand years. He also appealed to Vallisneri as an authority to prove that the mineral masses containing shells bore, upon the whole, but a small proportion to those rocks which were destitute of organic remains; and the latter, says the learned mons, might have been created as they now exist, in the beginning. Generelli then deseribes the continual waste of mountains and continents, by the action of rivers and torrents, and concludes with these eloquent and original observations :— ‘Is it possible that this waste should have continued for six thousand, and perhaps a greater number of years, and that the mountains should remain so great, unless their ruins have been repaired? Is it credible that the Author of Nature should have founded the world upon such laws, as that the dry land should for ever be growing smaller, and at last become wholly submerged beneath the waters ? Is it credible that, amid so many created things, the moun- tains alone should daily diminish in number and bulk, without there being any repair of their losses ? This would be contrary to that order of Providence which is seen to reign in all other things in the universe. Wherefore | deem it just to conclude, that the same cause which, in the be- ginning of time, raised mountains from the abyss, has down to the present day continued to produce others, in order to restore from time to time the losses of all such as sink down in different places, or are rent asunder, or in other way suffer disintegration. If this be admitted, we can easily understand why there should now be found upon many mountains so great a number of crustacea and other marine animals.’ Tn the above extract, I have not merely enumerated the opinions and facts which are confirmed by recent observa- tion, suppressing all that has since proved to be erroneous, 56 MARSILLI. [Cu. Tir. but have given a faithful abridgment of the entire treatise with the omission only of Moro’s hypothesis, which Generelli adopted, with all its faults and excellences. The reader will therefore remark, that although this admirable essay em- braces so large a portion of the principal objects of geological research, it makes no allusion to the extinction of certain classes of animals ; and it is evident that no opinions on this head had, at that time, gained a firm footing in Italy. That Lister and other English naturalists should long before have declared in favour of the loss of species, while Scilla and most of his countrymen hesitated, was perhaps natural, since the Italian museums were filled with fossil shells belonging to: species of which a great portion did actually exist in the Mediterranean ; whereas the English collectors could obtain no recent species from such of their own strata as were then explored. The weakest point in Moro’s system consisted in deriving all the stratified rocks from voleanic ejections; an absurdity which his opponents took care to expose, especially Vito Amici.* Moro seems to have been misled by his anxious desire to represent the formation of secondary rocks as having occupied an extremely short period, while at the same time he wished to employ known agents in nature. To imagine torrents, rivers, currents, partial floods, and all the operations of moving water, to have gone on exerting an energy many thousand times greater than at present, would have appeared preposterous and incredible, and would have required a hundred violent hypotheses; but we are so unacquainted with the true sources of subterranean disturbances, that their former violence may in theory be multiphed indefinitely, without its being possible to prove the same manifest con- tradiction or absurdity in the conjecture. For this reason, perhaps, Moro preferred to derive the materials of the strata rom volcanic ejections, rather than from transportation’ by running water. Marsilli.—Marsilli, whose work is alluded to by Generelli, had been prompted to institute enquiries into the bed of the Adriatic, by discovering, in the territory of Parma, (what * Sui Testacei della Sicilia. Cu. IIL] DONATI.—BALDASSARI.—BUFFON. 57 Spada had observed near Verona, and Schiavo in Sicily,) that fossil shells were not scattered through the rocks at random, but disposed in regular order, according to certain genera and species. Vitaliano Donati, 1750.—But with a view of throwing further light upon these questions, Donati, in 1750, undertook a more extensive investigation of the Ad riatic, and discovered, by numerous soundings, that deposits of sand, marl, and tufaceous incrustations, most strictly analogous to those of the Subapennine hills, were in the act of accumulating there. He ascertained that there were no shells in some of the sub- marine tracts, while in other places they lived together in families, particularly the genera Arca, Pecten, Venus, Murex, and some others. He also states that in divers localities he found a mass composed of corals, shells; and crustaceous bodies of different species, confusedly blended with earth, sand, andgravel. Atthe depth of a foot or more, the organic substances were entirely petrified and reduced to marble; at less than a foot from the surface, they approached nearer to their natural state; while at the surface they were alive, or, if dead, in a good state of preservation. Baldassari.—A contemporary naturalist, Baldassari, had shown that the organic remains in the tertiary marls of the Siennese territory were grouped in families, in a manner precisely similar to that above alluded to by Donati. Buffon, 1749.—Buffon first made known his theoretical views concerning the former changes of the earth, in his Natural History, published in 1749. He adopted the theory of an original volcanic nucleus, together with the universal ocean of Leibnitz. By this aqueous envelope the highest mountains were once covered. Marine currents then acted violently, and formed horizontal strata, by washing away solid matter in some parts, and depositing it in others; they also excavated deep submarine valleys. The level of the ocean was then depressed by the entrance of a part of its waters into subterranean caverns, and thus some land was left dry. Buffon seems not to have profited, like Leibnitz and Moro, by the observations of Steno, or he could not have imagined that the strata were generally horizontal, and 53 BUFFON. [Cu IIT, that those which contained organic remains had never heen disturbed since the era of their formation. He was conscious of the great power annually exerted by rivers and marine currents in transporting earthy materials to lower levels, ang he even contemplated the period when they would destroy all the present continents. Although in geology he wag not an original observer, his genius enabled him to render his hypothesis attractive; and by the eloquence of his style, and the boldness of his speculations, he awakened curiosity, and provoked a spirit of enquiry among his countrymen. Soon after the publication of his ‘ Natural History,’ in which was included his ‘Theory of the Earth,’ he received an official letter (dated January, 1751) from the Sorbonne, or Faculty of Theology in Paris, informing him that fourteen pro- positions in his works ‘ were reprehensible, and contrary to the creed of the church.’ The first of these obnoxious passages, and the only one relating to geology, was as follows :--‘ The waters of the sea have produced the mountains and valleys of the land—the waters of the heavens, reducing all to a level, will at last deliver the whole land over to the sea, and the sea successively prevailing over the land, will leave dry new continents like those which we inhabit.’ Buffon was invited by the College, in very courteous terms, to send in an explanation, or rather a recantation of his unorthodox opinions. To this he submitted; and a general assembly of the Faculty having approved of his ‘ Declaration,’ he was required to publish it in his next work. The document begins with these words :—‘I declare that I had no intention to contradict the text of Scripture; that I believe most firmly all therein related about the creation, both as to order of time and matter of fact; and I abandon everything m my book respecting the formation of the earth, and, generally, all which may be contrary to the narration of Moses.’ The grand principle which Buffon was called upon to re- nounce was simply this,—‘that the present mountains and valleys of the earth are due to secondary causes, and that the same causes will in time destroy all the continents, hills, and valleys, and reproduce others like them.’ Now, * Hist. Nat. tom. vy. 6d. de l’Imp. Royale, Paris, 1769. Cu. IIL] TARGIONI.—LEHMAN. A) whatever may be the defects of many of his views, it is no longer controverted that the present continents are of secondary origin. The doctrine is as firmly established as the earth’s rotation on its axis; and that the land now elevated above the level of the sea will not endure for ever, is an opinion which gains ground daily, in proportion as we enlarge our experience of the changes now in progress. Targioni, in his voluminous ‘Travels in Targioni, 1751. Tuscany, 1751 and 1754,’ laboured to fill up the sketch of the geology of that region left by Steno sixty years before. Notwithstanding a want of arrangement and condensation in his memoirs, they contained a rich store of faithful obser- vations. He has not indulged in many general views, but in regard to the origin of valleys, he was opposed to the theory of Buffon, who attributed them principally to sub- marine currents. The Tuscan naturalist laboured to show that both the larger and smaller valleys of the Apennines were excavated by rivers and floods, caused by the bursting of the barriers of lakes, after the retreat of the ocean. He also maintained that the elephants and other quadrupeds, so frequent in the lacustrine and alluvial deposits of Italy, had inhabited that peninsula ; and had not been transported thither, as some had conceived, by Hannibal or the Romans, nor by what they were pleased to term ‘a catastrophe of nature.’ Lehman, 1756.—In the year 1756 the treatise of Lehman, a German mineralogist, and director of the Prussian mines, appeared, who also divided mountains into three classes : the first, those formed with the world, and prior to the creation of animals, and which contained no fragments of other rocks; the second class, those which resulted from the partial destruction of the primary rocks by a general revolu- tion; and a third class, resulting from local revolutions, and in part from the deluge of Noah. A French translation of this work appeared in 1759, in the preface of which, the translator displays very enlightened views respecting the operations of earthquakes, as well as of the aqueous causes.* * Essai d'une Hist. Nat. des Couches de la Terre, 1759. 60 GESNER.—ARDUINO. [Cu Ty, Gesner, 1758.—In this year Gesner, the botanist, of Zurich, published an excellent treatise on petrifactions, and the changes of the earth which they testify.* After a detailed enumeration of the various classes of fossils of the animal and vegetable kingdoms, and remarks on the different states in which they are found petrified, he considers the geological phenomena connected with them ; observing, that some, like those of Giningen, resembled the testacea, fish, and plants indigenous in the neighbouring region ;+ while some, such as ammonites, gryphites, belemnites, and other shells, are either of unknown species, or found only in the Indian or other distant seas. In order to elucidate the structure of the earth, he gives sections, from Verenius, Buffon, and others, obtained in digging wells; distinguishes between horizontal and inclined strata; and, in speculating on the causes of these appearances, mentions Donati’s examination of the bed of the Adriatic; the filling up of lakes and seas by sediment ; the imbedding of shells, now in progress ; and many known effects of earthquakes, such as the sinking down of districts, or the heaving up of the bed of the sea, so as to form new islands, and lay dry strata containing petrifactions. The ocean, he says, deserts its shores in many countries, as on the borders of the Baltic; but the rate of recession has been so slow in the last 2,000 years, that to allow the Apen- nines, whose summits are filled with marine shells, to emerge to their present height, would have required about 80,000 years,—a lapse of time ten times greater, or more, than the age of the universe. We must therefore refer the phenomenon to the command of the Deity, related by Moses, that ‘the waters should be gathered together in one place, and the dry land appear.’ Gesner adopted the views of Leibnitz, to account for the retreat of the primeval ocean: his essay dis- plays much erudition ; and the opinions of preceding writers of Italy, Germany, and England, are commented upon with fairness and discrimination. : Ardwino, 1759.—In the year following, Arduino,t in his memoirs on the mountains of Padua, Vicenza, and Verona, * John Gesner published at Leyden, + Part ii. chap. 9. ae in Latin. { Giornale de’ Criselini, 1759. Cx. IT.] MICHELL.—CATCOTT. 61 deduced, from original observations, the distinction of rocks into primary, secondary, and tertiary, and showed that in those districts there had been a succession of submarine volcanic eruptions. Michell, 1760.—In the following year (1760) the Rev. John Michell, Woodwardian Professor of Mineralogy at Cambridge, published in the Philosophical Transactions, an Hssay on the Cause and Phenomena of Harthquakes.* His attention had been drawn to this subject by the great earthquake of Lisbon in 1755. He advanced many original and philoso- phical views respecting the propagation of subterranean movements, and the caverns and fissures wherein steam might be generated. In order to point out the application of his theory to the structure of the globe, he was led to describe the arrangement and disturbance of the strata, their usual horizontality in low countries, and ‘their contortions and fractured state in the neighbourhood of mountain chains. He also explained, with surprising accuracy, the relations of the central ridges of older rocks to the ‘long narrow slips of similar earth, stones, and minerals,’ which are parallel to these ridges. In his generalisations, derived in great part from his own observations on the geological structure of Yorkshire, he anticipated many of the views more fully developed by later naturalists. Catcott, 1761.—Michell’s papers were entirely free from all physico-theological disquisitions, but some of his contempo- raries were still earnestly engaged in defending or impugn- ing the Woodwardian hypothesis. We find many of these * See a Sketch of the History of En- and to have entirely discontinued his glish Geology, by Dr. Fitton, in Edinb. en pursuits, exemplifying the Rev. Feb. 1818, re- uae rag and working of a system still in force at Edinb. Phil. Mag. vol. i. . 1832- ace and Cambridge, where the chairs . Some of Michelt’s Baek ations mathematics, anbural philosophy, anticipate in so remarkable a manner aaa botany, astronomy, geology, e theories established forty sae mineralogy, and others, being frequently afterwards, that his writings would p filled by clergymen, the reward of suc- bably have formed an the science, —_ cess disqualifies them, if they conscien- benefice. From that time he a rs have been engaged in his clerical duties, ° labours would naturally bear the richest ruits, tad 62 FORTIS.—ODOARDI.—RASPE. [Cr Ty writings referred to by Catcott, an Hutchinsonian, who pub. lished a ‘Treatise on the Deluge’ in 1761. He laboureg particularly to refute an explanation offered by his contem- porary, Bishop Clayton, of the Mosaic writings. That prelate had declared that the deluge ‘could not be literally true, save in respect to that part where Noah lived before the flood.’ Catcott insisted on the universality of the deluge, and referred to traditions of inundations mentioned by ancient writers, or by travellers, in the Hast Indies, China, South America, and other countries. This part of his book is valuable, although it is not easy to see what bearing the. traditions have, if admitted to be authentic, on the Bishop's argument, since no evidence is adduced to prove that the catastrophes were contemporaneous events, while some of them are expressly represented by ancient authors to have occurred in succession. Fortis—Odoardi, 1761.—The doctrines. of Arduino, above adverted to, were afterwards confirmed by Fortis and Des- marest, in their travels in the same country; and they, as well as Baldassari, laboured to complete the history of the Subapennine strata. In the work of Odoardi,* there was also a clear argument in favour of the distinct ages of the older Apennine strata, and the Subapennine formations of more recent origin. He pointed out that the strata of these two eroups were wncomformable, and must have been the deposits of different seas at distant periods of time. — Raspe, 1763.—A history of the new islands by Raspe, an Hanoverian, appeared in 1763, in Latin.t+ In this work, all the authentic accounts of earthquakes which had produced permanent changes on the solid parts of the earth were collected together and examined with judicious criticism. The best systems which had been proposed concerning the ancient history of the globe, both by ancient and modern writers, are reviewed; and the merits and defects of the doctrines of Hooke, Ray, Moro, Buffon, and others, fairly * Sui Corpi Marini del Feltrino, losophical Works of Leibnitz. Amst 1761. ae eipzig, 1765 ;’ also author of ‘ a e's De Novis e Mari Natis Insulis. Gems,’ and ‘ Baron Munchausen’s Raspe was also the editor of the ‘ Phi- Trayels.’ Cu. HT.) RASPE.—FUCHSEL. 63 estimated. Great admiration is expressed for the hypothesis of Hooke, and his explanation of the origin of the strata is shown to have been more correct than Moro’s, while their theory of the effects of earthquakes was the same. Raspe had not seen Michell’s memoirs, and his views concerning the geological structure of the earth were perhaps less enlarged ; yet he was able to add many additional arguments in favour of Hooke’s theory, and to render it, as he said, a nearer approach to what Hooke would have written had he lived in later times. As to the periods wherein all the earth- quakes happened, to which we owe the elevation of various parts of our continents and islands, Raspe says he pretends not to assign their duration, still less to defend Hooke’s sug- gestion, that the convulsions almost all took place during the deluge of Noah. He adverts to the apparent indications of the former tropical heat of the climate of Europe, and the changes in the species of animals and plants, as among the most obscure and difficult problems in geology. in regard to the islands raised from the sea, within the times of history or tradition, he declares that some of them were composed of strata containing organic remains, and that they were not, as Buffon had asserted, made of mere volcanic matter. His work concludes with an eloquent exhortation to naturalists to examine the isles which rose, in 1707, in the Grecian Archipelago, and, in 1720, in the Azores, and not to neglect such splendid opportunities of studying nature ‘in the act of parturition.’ That Hooke’s writings should have been neglected for more than half a century, was mat- ter of astonishment to Raspe; but it is still more wonderful that his own luminous exposition of that theory should, for more than another half century, have excited so little interest. Fuchsel, 1762-1773.—Fuchsel, a German physician, pub- lished, in 1762, a geological description of the country between the Thuringerwald and the Hartz, and a memoir on the environs of Rudolstadt;* and afterwards, in 1773, a theoretical work on the ancient history of the earth and of * Acta Academie Electoralis Maguntine, vol. ii. Erfurt. 64 FUCHSEL.—BRANDER. [Ce Ti man.* He had evidently advanced considerably beyond hig predecessor Lehman, and was aware of the distinctness, both as to position and fossil contents, of several groups of strata of different ages, corresponding to the secondary for. mations now recognised by geologists in various parts of Germany. He supposed the Huropean continents to have remained covered by the sea until the formation of the marine strata called in Germany ‘ muschelkalk,’ at the same time that the terrestrial plants of many Huropean deposits, attested the existence of dry land which bordered the ancient sea; land which, therefore, must have occupied the place of the present ocean. This pre-existing continent had been gradually swallowed up by the sea, different parts having sub- sided in succession into subterranean caverns. All the sedimentary strata were originally horizontal, and their present state of derangement must be referred to subsequent oscillations of the ground. As there were plants and animals in the ancient periods, so also there must have been men, but they did not all descend from one pair, but were created at various points on the earth’s surface ; and the number of these distinct birth- places was as great as are the original languages of nations. In the writings of Fuchsel we see a strong desire mani- fested to explain geological phenomena as far as possible by reference to the agency of known causes; and although some of his speculations were fanciful, his views coincide much more nearly with those now generally adopted, than the theories afterwards promulgated by Werner and his followers. Brander, 1766.—Gustavus Brander published, in 1766, his ‘ Fossilia Manicure. containing excellent figures of fossil shells from the more modern ior Eocene) marine strata of Hampshire. ‘Various opinions,’ he says in the preface, ‘ had been entertained concerning the time when and how these bodies became deposited. Some there are who conceive that it might have been effected in a wonderful length of time by a gradual changing and shifting of the sea,’ &e. But the : , j 5 de This account of Fuchsel is derived moirs by M. Keferstein. Journ. from an excellent analysis of his me- Géologie, tom. ii, Oct. 830. Cu. III.] SOLDANI.—FORTIS.—TESTA. 65 most common cause assigned is that of ‘the deluge.’ This conjecture, he says, even if the “aaa of the flood be not called in question, is purely hypothetical. In his opinion, fossil animals and testacea were, for the most part, of unknown species ; and of such as were known, the living analogues now belonged to southern latitudes. Soldani, 1780.—Soldani applied successfully his know- ledge of zoology to illustrate the history of stratified masses. He explained that microscopic testacea and zoophytes inha- bited the depths of the Mediterranean; and that the fossil species were, in like manner, found in those deposits wherein the fineness of their particles, and the absence of pebbles, implied that they were accumulated in a deep sea, or far from shore. This author first remarked the alternation of marine and freshwater strata in the Paris basin.* Fortis—Testa, 1793.—A. lively controversy arose between Fortis and another Italian naturalist, Testa, concerning the fish of Monte Bolea, in 1793. Their letters,+ written with ereat spirit and elegance, show that they were aware that a large proportion of the Subapennine shells were identical with living species, and some of them with species now living in the torrid zone. Fortis proposed a somewhat fanciful conjecture, that when the volcanos of the Vicentin were burning, the waters of the Adriatic had a higher tempera- ture; and in this manner, he said, the shells of warmer regions may once have peopled their own seas. But Testa was disposed to think that these species of testacea were still common to their own and to equinoctial seas : for many, he said, once supposed to be confined to hotter regions, had been afterwards discovered in the Mediterranean.t * Saggio orittografico, &c. 1780, and ments made by that distinguished hy- Works. ag drographer, the late Aghiiral Smyth, on ae ay Pesci Fossili di Bolea. the water within eight fathoms of the Milan, 1 surface, that the temperature of the ik ae ba of Testa has been Mediterranean is on an average 34° strengthened of late years by the dis- covery, that dealers in shells had long been in the habit of selling Mediterra- nean species as shells of more southern and distant mene for the an of enhancing their pric It appears, moreover, from sey ae hundred ie of Fahrenheit higher than the Western part of the Atlantic ocean; an important fact, which in some de a explain wh may help to es are common to tropical latitudes aaa to the Mediter- anean, 66 CORTESIL—PALLAS.—SAUSSURE, [Cu. IIT Cortesi — Spallanzant — Wallerius — Whitehurst.— While these Italian naturalists, together with Cortesi and Spallan- yani, were busily engaged in pointing out the analogy be. tween the deposits of modern and ancient seas, and the habits and arrangements of their organic inhabitants, and while some progress was making, in the same country, in investigating the ancient and modern volcanic rocks, some of the most original observers among the English and German writers, Whitehurst * and Wallerius, were wasting their strength in contending, according to the old Woodwardian hypothesis, that all the strata were formed by Noah’s deluge. But Whitehurst’s description of the rocks of Derbyshire was most faithful; and he atoned for false theoretical views, by providing data for their refutation. Pallas—Saussure.—Towards the close of the eighteenth century, the idea of distinguishing the mineral masses on our globe into separate groups, and studying their relations, began to be generally diffused. Pallas and Saussure were among the most celebrated whose labours contributed to this end. After an attentive examination of the two great mountain chains of Siberia, Pallas announced the result, that the granite rocks were in the middle, the schistose at their sides, and the limestones again on the outside of these ; and this he conceived would prove a general law in the formation of all chains composed chiefly of primary rocks.t In his ‘Travels in Russia,’ in 1793 and 1794, he made many geological observations on the recent strata near the Wolga and the Caspian, and adduced proofs of the greater extent of the latter sea at no distant era in the earth's history. His memoir on the fossil bones of Siberia attracted attention to some of the most remarkable phenomena in geology. He stated that he had found a rhinoceros entire m the frozen soil, with its skin and flesh: an elephant, found afterwards in a mass of ice on the shore of the North Sea, removed all doubt as to the accuracy of so wonderful a dis- covery.{ ». 1778, part i * Inquiry into the Original State and tains. Act. Petrop. ant = 3 Nov. comm. Petr. XVII. Cuviels ied Z Formation of the Earth, 1778. + + Observ. onthe Formation of Moun- — Eloge de Pallas. . <7 ys w Cu. IIT.] SAUSSURE. 67 The subjects relating to the natural history which engaged the attention of Pallas, were too multifarious to admit of his devoting a large share of his labours exclusively to geology. Saussure, on the other hand, employed the chief portion of his time in studying the structure of the Alps and Jura, and he provided valuable data for those who followed him. He did not pretend to deduce any general system from his nu- merous and interesting observations ; and the few theoretical opinions which escaped from him, seem, like those of Pallas, to have been chiefly derived from the cosmological specu- lations of preceding writers. CHAPTER IV. HISTORY OF THE PROGRESS OF GEOLOGY —continued, WERNER’S APPLICATION OF GEOLOGY TO THE ART OF MINING—EXCURSIVE CHARACTER OF HIS LECTURES—ENTHUSIASM OF HIS PUPILS—HIS AUTHORITY— HIS THEORETICAL ERRORS—DESMAREST'S MAP AND DESCRIPTION OF AUVERGNE ILLUSTRATIONS—INFLUENCE OF VOLTAIRE S WRITINGS ON GEOLOGY— IMPU- TATIONS CAST ON THE HUTTONIANS BY WILLIAMS, KIRWAN, AND DE LUC— SMITHS MAP OF ENGLAND—GEOLOGICAL SOCIETY OF LONDON—PROGRESS OF THE SCIENCES IN FRANCE— GROWING IMPORTANCE OF THE STUDY OF ORGA- NIC REMAINS WerNer.—The art of mining had long been taught m France, Germany, and Hungary, in scientific institutions es- tablished for that purpose, where mineralogy has always been a principal branch of instruction. Werner was named, in 1775, professor of that science in the ‘ School of Mines,’ at Freyberg, in Saxony. He directed his attention not merely to the composition and external characters of minerals, but also to what he termed “ge0g- nosy,’ or the natural position of minerals in particular rocks, together with the grouping of those rocks, their ceographical distribution, and various relations. The phenomena ob- served in the structure of the globe had hitherto served for little else than to furnish interesting topics for philosophical discussion: but when Werner pointed out their application to the practical purposes of mining, they were instantly re- garded by a large class of men as an essential part of their professional education, and from that time the science was ultivated in Europe more ardently and systematically. Werner’s mind was at once imaginative and _ richly stored with miscellaneous knowledge. He associated every Cu. IV.] WERNER. 69 thing with his favourite science, and in his excursive lec- tures, he pointed out all the economical uses of minerals, and their application to medicine: the influence of the mineral composition of rocks upon the soil, and of the soil upon the resources, wealth, and civilisation of man. The vast sandy plains of Tartary and Africa, he would say, re- tained their inhabitants in the shape of wandering shepherds ; the granitic mountains and the low calcareous and alluvial plains gave rise to different manners, degrees of wealth, and intelligence. The history even of languages, and the migra- tions of tribes, had been determined by the direction of particular strata. The qualities of certain stones used in building would lead him to descant on the architecture of different ages and nations; and the physical geography of a country frequently invited him to treat of military tactics. The charm of his manners and his eloquence kindled en- thusiasm in the minds of his pupils; and many, who had intended at first only to acquire a slight knowledge of mineralogy, when they had once heard him, devoted them- selves to it as the business of their lives. In a few years, a small school of mines, before unheard of in Europe, was raised to the rank of a great university; and men already distinguished in science studied the German language, and came from the most distant countries to hear the great oracle of geology.* Werner had a great antipathy to the mechanical labour of writing, and, with the exception of a valuable treatise on metalliferous veins, he could never be persuaded to pen more than a few brief memoirs, and those containing no develop- ment of his general views. Although the natural modesty of his disposition was excessive, approaching even to timidity, he indulged in the most bold and sweeping generalisations, and he inspired all his scholars with a most implicit faith in his doctrines. Their admiration of his genius, and the feel- ings of gratitude and friendship which they all felt for him, were not undeserved; but the supreme authority usurped by him over the opinions of his contemporaries, was eventually prejudicial to the progress of the science; so much so, as * Cuvier, Eloge de Werner. 70 WERNER. (Cu. LV, ereatly to counterbalance the advantages which it derived from his exertions. If it be true that delivery be the first, secon and third requisite in a popular orator, it 1s no less certain, that to travel is of first, second, and third importance to those who desire to originate just and comprehensive views concerning the structure of our globe. Now Werner had not travelled to distant countries; he had merely explored a small portion of Germany, and conceived, and persuaded others to believe that the whole surface of our planet, and all the mountain chains in the world, were made after the model of his own province. It became a ruling object of ambition in the minds of his pupils to confirm the generalisations of their great master, and to discover in the most distant parts of the globe his ‘universal formations,’ which he supposed had been each in succession simultaneously precipitated over the whole earth from a common menstruum, or ‘ chaotic fluid.’ It now appears that the Saxon professor had misinterpreted many of the most important appearances even in the im- mediate neighbourhood of Freyberg. Thus, for example, within a day’s journey of his school, the porphyry, called by him primitive, has been found not only to send forth veins or dikes through strata of the coal formation, but to overlie them in mass. The granite of the Hartz mountains, on the other hand, which he supposed to be the nucleus of the chain, is now well known to traverse the other beds, as near Goslar; and still nearer Freyberg, in the Erzgebirge, the mica slate does not mantle round the granite as was sup- posed, but abuts abruptly against it. Fragments, also, of the greywacke slate, containing organic remains, were found entangled in the granite of the Hartz, by M. de Seckendorf.* The principal merit of Werner’s system of instruction con- sisted in steadily directing the attention of his scholars t0 the constant relations of superposition of certain mineral groups; but he had been anticipated, as has been shown in the last chapter, in the discovery of this general law, by * Tam indebted for this information and partly to Dr. Charles Hartman? partly to Messrs. Sedgwick and Murchi- the translator of this work ito Ger- son, who have investigated the country, n. Cn. IV.] VULCANISTS AND NEPTUNISTS. al several geologists in Italy and elsewhere ; and his leading divisions of the secondary strata were at the same time, and independently, made the basis of an arrangement of the British strata by our countryman, William Smith, to whose work I shall refer in the sequel. Controversy between the Vulcanists and Neptunisis—In re- gard to basalt and other igneous rocks, Werner’s theory was original, but it was also extremely erroneous. The basalts of Saxony and Hesse, to which his observations were chiefly confined, consisted of tabular masses capping the hills, and not connected with the levels of existing valleys, like many in Auvergne and the Vivarais. These basalts, and all other rocks of the same family in other countries, were, according to him, chemical precipitates from water. He denied that they were the products of submarine. volcanos; and even taught that, in the primeval ages of the world, there were no volcanos. His theory was opposed, in a twofold sense, to the doctrine of the permanent agency of the same causes in nature ; for not only did he introduce, without scruple, many imaginary causes supposed to have once effected great revo- lutions in the earth, and then to have become extinct, but new ones also were feigned to have come into play in modern times ; and, above all, that most violent instrument of change, the agency of subterranean heat. So early as 1768, before Werner had commenced his mineralogical studies, Raspe had truly characterised the basalts of Hesse as of igneous origin. Arduino, we have seen, had pointed out numerous varieties of trap-rock in the Vicentin as analogous to volcanic products, and as distinctly referable to ancient submarine eruptions. Desmarest, as before stated (p. 62), had, in company with Fortis, examined the Vicentin in 1766, and confirmed Arduino’s views. In 1772, Banks, Solander, and Troil compared the columnar basalt of Hecla with that of the Hebrides. Collini, in 1774, recognised the true nature of the igneous rocks on the Rhine, between Andernach and Bonn. In 1775, Guettard visited the Vivarais, and established the relation of basaltic currents to lavas. Lastly, in 1779, Faujas published his description of the volcanos of the Vivarais and Velay, and 72 DESMAREST. (Cu. IV, showed how the streams of basalt had poured out from erateps which still remain in a perfect state.* Desmarest—When sound opinions had thus for twenty years prevailed in Europe concerning the true nature of the ancient trap-rocks, Werner by his simple dictum caused g retrograde movement, and not only overturned the true theory, but substituted for it one of the most unphilosophical that can well be imagined. The continued ascendancy of his dogmas on this subject was the more astonishing, because a variety of new and striking facts were ddly accumulated in favour of the correct opinions previously entertained. Des- marest, after a careful examination of Auvergne, pointed out, first, the most recent volcanos which had their craters still entire, and their streams of lava conforming to the level of the present river-courses. He then showed that there were others of an intermediate epoch, whose craters were nearly effaced, and whose lavas were less intimately connected with the present valleys; and, lastly, that there were volcanic rocks, still more ancient, without any discernible craters or scorie, and bearing the closest analogy to rocks in other parts of Europe, the igneous origin of which was denied by the school of Freyberg.t Desmarest’s map of Auvergne was a work of uncommon merit. He first made a trigonometrical survey of the district, and delineated its physical geography with minute accuracy and admirable graphic power. He contrived, at the same time, to express without the aid of colours, many geological details, including the different ages and sometimes even the structure, of the volcanic rocks, and distinguishing them from the fresh-water and the granitic. They alone who have care- fully studied Auvergne, and traced the different lava streams from their craters to their termination,—the various isolated basaltic cappings,—the relation of some lavas to the present valleys,—the absence of such relations in others,—can appre ciate the extraordinary fidelity of this elaborate work. No other district of equal dimensions in Europe exhibits, perhaps, so beautiful and varied a series of phenomena; and, fortu- * Cuvier, Eloge de Desmarest. and Mém. del’Inst., Sciences Mathémat. + Journ. de Phys. vol. xiii. p.115; et Phys. vol. vi. p. 219. 3: &. @ 2 2 FF a2 SS Paes &. Gu..IV.] DOLOMIEU.—MONTLOSIER.—HUTTON. 73 nately, Desmarest possessed at once the mathematical know- ledge required forthe construction of a map, skill in mineralogy, and a power of original generalisation. Dolomiew-—Montlosier.—Dolomieu, another of Werner’s contemporaries, had found prismatic basalt among the ancient lavas of Etna; and, in 1784, had observed the alternations of submarine lavas and calcareous strata in the Val di Noto, in Sicily.* In 1790, also, he described similar phenomena in the Vicentin and in the Tyrol.t Montlosier published, in 1788, an essay on the theory of the voleanos of Auvergne, combining accurate local observations with comprehensive views. Notwithstanding this mass of evidence, the scholars of Werner were prepared to support his opinions to their utmost extent; maintaining, in the fulness of their faith, that even obsidian was an aqueous precipitate. As they were blinded by their veneration for the great teacher, they were impatient of opposition, and soon imbibed the spirit of a faction ; and their opponents, the Vulcanists, were not long in becoming contaminated with the same intemperate zeal. Ridicule and irony were weapons more frequently employed than argument by the rival sects, till at last the controversy was carried on with a degree of bitterness almost unprece- dented in questions of physical science. . Desmarest alone, who had long before provided ample materials for refuting such a theory, kept aloof from the strife ; and whenever a zealous Neptunist wished to draw the old man into an argu- ment, he was satisfied with replying, ‘Go and see.’ { Hutton, 1788.—It would be contrary to all analogy, in matters of graver import, that a war should rage with such fury on the Continent, and that the inhabitants of our island should not mingle in the affray. Although in England the personal influence of Werner was wanting to stimulate men to the defence of the weaker side of the question, they con- trived to find good reason for espousing the Wernerian errors with great enthusiasm. In order to explain the peculiar motives which led many to enter, even with party feeling, into this contest, it will be necessary to present the reader * Journ. de Phys. xxv. p. 191. { Cuvier, Eloge de Desmarest. + Ibid. tom. xxxvii. part ii. p. 200. 74 HUTTONIAN THEORY. [ Cu. Iv, with a sketch of the views unfolded by Hutton, a contempo- rary of the Saxon geologist. The former naturalist had been educated as a physician, but declining the practice of meqj- cine, he resolved, when young, to remain content with the small independence inherited from his father, and thenceforth to give his undivided attention to scientific pursuits. He resided at Edinburgh, where he enjoyed the society of many men of high attainments, who loved him for the simplicity of his manners and the sincerity of his character. His appli- cation was unwearied ; and he made frequent tours through different parts of England and Scotland, acquiring consider- able skill as a mineralogist, and constantly arriving at grand and comprehensive views in geology. He communicated the results of his observations unreservedly, and with the fearless spirit of one who was conscious that love of truth was the sole stimulus of his exertions. When at length he had matured his views, he published, in 1788, his ‘Theory of the Harth, * and the same, afterwards more fully developed in a separate work, in 1795. This treatise was the first in which geology was declared to be in no way concerned about ‘questions as to the origin of things ;’ the first in which an attempt was made to dispense entirely with all hypothetical causes, and to explain the former changes of the earth’s crust by reference exclusively to natural agents. Hutton laboured to give fixed principles to geology, as Newton had succeeded in doing to astronomy; but, in the former science, too little progress had been made towards furnishing the necessary data, to enable any philosopher, however great his genius, to realise so noble a project. Huttonian theory.—‘The ruins of an older world,’ said Hutton, ‘are visible in the present structure of our planet; and the strata which now compose our continents have been once beneath the sea, and were formed out of the waste of pre-existing continents. The same forces are still destroying; by chemical decomposition or mechanical violence, eve? the hardest rocks, and transporting the materials to the sea, where they are spread out, and form strata analogous to those of more ancient date. Although loosely deposited along the * Ed. Phil. Trans. 1788. Cx. IV.] HUTTONIAN THEORY. 75 bottom of the ocean, they become afterwards altered and con- solidated by volcanic heat, and then heaved up, fractured, and contorted.’ Although Hutton had never explored any region of active yoleanos, he had convinced himself that basalt and many other trap-rocks were of igneous origin, and that many of them had been injected in a melted state through fissures in the older strata. ‘The compactness of these rocks, and their different aspect from that of ordinary lava, he attributed to their having cooled down under the pressure of the sea; and in order to remove the objections started against this theory, his friend, Sir James Hall, instituted a most curious and in- structive series of chemical experiments, illustrating the erystalline arrangement and texture assumed by melted matter cooled under high pressure. The absence of stratification in granite, and its analogy, in mineral character, to rocks which he deemed of igneous ori- gin, led Hutton to conclude that granite also must have been formed from matter in fusion; and this inference he felt could not be fully confirmed, unless he discovered at the contact of granite and other strata a repetition of the pheno- mena exhibited so constantly by the trap-rocks. Resolved to try his theory by this test, he went to the Grampians, and surveyed the line of junction of the granite and superincum- bent stratified masses, until he found in Glen Tilt, in 1785, the most clear and unequivocal proofs in support of his views. Veins of red granite are there seen branching out from the principal mass, and traversing the black micaceous schist and primary limestone. The intersected stratified rocks are so distinct in colour and appearance as to render the example in that locality most striking, and the alteration of the lime- stone in contact was very analogous to that produced by trap veins on calcareous strata. This verification of his system filled him with delight, and called forth such marks of joy and exultation, that the guides who accompanied him, says his biographer, were convinced that he must have discovered a vein of silver or gold.* He was aware that the same theory would not explain the origin of the primary schists, * Playfair’s Works, vol. iv. p. 75. 76 HUTTONIAN THEORY. Cu. IV, but these he called primary, rejecting the term primitive, ang was disposed to consider them as sedimentary rocks altered by heat, and that they originated in some other form from the waste of previously existing rocks. By this important discovery of granite veins, to which he had been led by fair induction from an independent class of facts, Hutton prepared the way for the greatest innovation on the systems of his predecessors. Vallisneri had pointed out the general fact that there were certain fundamental rocks which contained no organic remains, and which he supposed to have been formed before the creation of living beings. Moro, Generelli, and other Italian writers, embraced the same doctrine; and Lehman regarded the mountains called by him primitive, as parts of the original nucleus of the globe. The same tenet was an article of faith in the school of Freyberg: and if anyone ventured to doubt the possibility of our being enabled to carry back our researches to the creation of the present order of things, the granitic rocks were triumphantly appealed to. On them seemed written, in legible characters, the memorable inscription— ‘Dinanzi a me nou fur cose create Se non eterne ; and no small sensation was excited when Hutton seemed, with unhallowed hand, desirous to erase characters already regarded by many as sacred. ‘In the economy of the world,’ said the Scotch geologist, ‘I can find no traces of a beginning, no prospect of an end;’ a declaration the more startling when coupled with the doctrine, that all past ages on the globe had been brought about by the slow agency of existing causes. The imagination was first fatigued and overpowered by endeavouring to conceive the immensity of time required for the annihilation of whole continents by so insensible a process; and when the thoughts had wandered through these interminable periods, no resting-place was assigned in the remotest distance. The oldest rocks weté ‘ Before ‘i things create were none, save things Kterne Dante’s Inferno, canto iii., Cary’s Translation. e Pa == | —— Cu. IV.] HUTTONIAN THEORY. 77 represented to be of a derivative nature, the last of an ante- cedent series, and that, perhaps, one of many pre-existing worlds. Such views of the immensity of past time, like those unfolded by the Newtonian philosophy in regard to space, were too vast to awaken ideas of sublimity unmixed with a painful sense of our incapacity to conceive a plan of such ‘nfinite extent. Worlds are seen beyond worlds immea- surably distant from each other, and, beyond them all, innumerable other systems are faintly traced on the confines of the visible universe. The characteristic feature of the Huttonian theory was, as before hinted, the exclusion of all causes not supposed to belong to the present order of nature. But Hutton had made no step beyond Hooke, Moro, and Raspe, in pointing out in what manner the laws now governing subterranean move- ments might bring about geological changes, if sufficient time be allowed. On the contrary, he seems to have fallen far short of some of their views, especially when he refused to attribute any part of the external configuration of the earth’s crust to subsidence. He imagined that the continents were first gradually destroyed by aqueous degradation ; and when their ruins had furnished materials for new continents, they were upheaved by violent convulsions. He therefore required alternate periods of general disturbance and repose: and such he believed had been, and would for ever be, the course of nature. Generelli, in his exposition of Moro’s system, had made a far nearer approximation towards reconciling geological ap- pearances with the state of nature as known to us; for while he agreed with Hutton, that the decay and reproduction of rocks were always in progress, proceeding with the utmost uniformity, the learned Carmelite represented the repairs of mountains by elevation from below to be effected by an equally constant and synchronous operation. Neither of these theories, considered singly, satisfies all the conditions of the great problem, which a geologist, who rejects cosmo- logical causes, is called upon to solve; but they probably contain together the germs of a perfect system. There can be no doubt, that periods of disturbance and repose have 78 PLAYFAIR’S ILLUSTRATIONS OF HUTTON. [Cu. Iv followed each other in succession in every region of the globe ; but it may be equally true, that the energy of the subterra- nean movements has been always uniform as regards the whole earth. The force of earthquakes may for a cycle of years have been invariably confined, as it is now, to large but determinate spaces, and may then have gradually shifted its position, so that another region, which had for ages been at rest, became in its turn the grand theatre of action. Playfair’s illustrations of Hutton.—The explanation proposed by Hutton, and by Playfair, the illustrator of his theory, respecting the origin of valleys and of alluvial accumulations, was also very imperfect. They ascribed valleys in general too exclusively to the action of the rivers now flowing in them, not allowing sufficiently for the excavating and transporting power which the waves of the ocean must exert on land during its emergence, nor for those inequalities of the surface which must be produced by movements accom- panying the upheaval of the land. Although Hutton’s knowledge of mineralogy and chemistry was considerable, he possessed but little information con- cerning organic remains; they merely served him, as they did Werner, to characterise certain strata, and to prove their marine origin. The theory of former revolutions in organic life was not yet fully recognised; and without this class of proofs in support of the antiquity of the globe, the indefinite periods demanded by the Huttonian hypothesis appeared visionary to many; and some, who deemed the doctrine inconsistent with revealed truths, indulged very uncharitable suspicions of the motives of its author. They accused him of a deliberate design of reviving the heathen dogma of an ‘eternal succession,’ and of denying that this world ever had a beginning. Playfair, in the biography of his friend, has the following comment on this part of their theory:—‘In the planetary motions, where geometry has carried the eye so far, both into the future and the past, we discover no mark either of the commencement or termina- tion of the present order. It is unreasonable, indeed, to suppose that such marks should anywhere exist. Author of Nature has not given laws to the universe, which, (ie eee a ee. a ee Re pe | ae <'s oy Rar er ae Cu. IV.] PLAYFAIR’S ILLUSTRATIONS OF HUTTON, 79 d like the institutions of men, carry in themselves the elements of their own destruction. He has not permitted in His works any symptom of infancy or of old age, or any sign by which we may estimate either their future or their past dura- tion. He may put an end, as He no doubt gave a beginning, to the present system, at some determinate period of time ; but we may rest assured that this great catastrophe will not be brought about by the laws now existing, and that it is not indicated by anything which we perceive.’* The party feeling excited against the Huttonian doctrines, and the open disregard of candour and temper in the con- troversy, will hardly be credited by the reader, unless he recalls to his recollection that the mind of the English pub- lic was at that time in a state of feverish excitement. A. class of writers in France had been labouring industriously for many years, to diminish the influence of the clergy, by sapping the foundations of the Christian faith; and their success, and the consequences of the Revolution, had alarmed the most resolute minds, while the imagination of the more timid was continually haunted by dread of innovation, as by the phantom of some fearful dream. Voltaire-—Voltaire had used the modern discoveries in physics as one of the numerous weapons of attack and ridi- cule directed by him against the Scriptures. He found that the most popular systems of geology were accommodated to the sacred writings, and that much ingenuity had been employed to make every fact coincide exactly with the Mosaic account of the creation and deluge. It was, therefore, with no friendly feelings that he contemplated the cultivators of geology in general, regarding the science as one which had been successfully enlisted by theologians as an ally in their cause.t He knew that the majority of those who were * Playfair’s Works, vol. iv. 5 + In allusion to the theories of Bur- net, Woodward, and other physico-theo- logical writers, he declared that the were as fond of changes of scene on the philosophers put themselves without ac 1 —Dissertation envoyée 4 l’ Academie de Boulogne, sur les Changemens arrivés face of the globe, as were the populace dans Shion: as Descartes framed it: for notre Globe.— Unfortunately, this and similar ridicule directed against the cosmogonists was too well deserved. 80 VOLTAIRE. | [Ca Ty. aware of the abundance of fossil shells in the interior o¢ continents, were still persuaded that they were proofs of the universal deluge; and as the readiest way of shaking thig article of faith, he endeavoured to inculcate scepticism ag to the real nature of such shells, and to recall from contempt the exploded dogma of the sixteenth century, that they were sports of nature. He also pretended that vegetable impres- sions were not those of real plants.* Yet he was perfectly convinced that the shells had really belonged to living tes- tacea, as may be seen in his essay ‘On the Formation of Mountains.’+ He would sometimes, in defiance of all con- sistency, shift his ground when addressing the vulgar; and, admitting the true nature of the shells collected im the Alps and other places, pretend that they were Hastern species, which had fallen from the hats of pilgrims coming from Syria. The numerous essays written by him on geological subjects were all calculated to strengthen prejudices, partly because he was ignorant of the real state of the science, and partly from his bad faith.t On the other hand, they who knew that his attacks were directed by a desire to invalidate Scripture, and who were unacquainted with the true merits of the question, might well deem the old diluvian hypothesis incontrovertible, if Voltaire could adduce no better argument against it than to deny the true nature of organic remains. It is only by careful attention to impediments originating in extrinsic causes, that we can explain the slow and reluct- ant adoption of the simplest truths in geology. First, we find many able naturalists adducing the fossil remains of marine animals as proofs of an event related in Scripture. The evidence is deemed conclusive by the multitude for a epee the chapter on ‘ Des Pierres t As an instanceof his desire to throw ficurés.’ doubt indiscriminately on all geological + In that essay he laysit down, ‘that data, we may recall the passage where all naturalists are now agreed that de- he says, that ‘the bones of a reindeer posits of shells in the midst of the con- and hippopotamus ia near tinents are monuments of the — Etampes did not prove, as some would occupation of these districts by the have it, that Lapland ace the Nile were Geansames nes ( ¢ >, when onceon a tour from Paris to Orleans, speaking of the fossil shells of Touraine, but merely that a lover of curiosities he admits their true origin. once preserved them in his cabinet. _ tation. Among these appears Wi Cu. IV.] SPIRIT OF INTOLERANCE, 81 century or more; for it favours opinions which they enter- tained before, and they are gratified by supposing them con- firmed by fresh and unexpected proofs. Many, who see through the fallacy, have no wish to undeceive those who are influenced by it, approving the effect of the delusion, and conniving at it asa pious fraud; until, finally, an opposite party, who are hostile to the sacred writings, labour to explode the erroneous opinion, by substituting for it another dogma which they know to be equally unsound. The heretical Vulcanists were soon after openly assailed in England, by imputations of the most illiberal kind. We cannot estimate the malevolence of such a persecution, by the pain which similar insinuations might now inflict ;. 208 although charges of infidelity and atheism must always be odious, they were injurious in the extreme at that moment of political excitement; and it was better, perhaps, for a man’s good reception in society, that his moral character should have been traduced, than that he should become a mark for these poisoned weapons. I shall pass over the works of numerous divines, who may be excused for sensitiveness on points which then excited so much uneasiness in the. public mind; and shall say nothing of the amiable poet Cowper,* who could hardly be expected to have enquired into the merit of doctrines in physics. But in the foremost ranks of the intolerant are found several laymen who had high claims to scientific repu- iams, a mineral surveyor a “Natural History of the work of great merit for that of Edinburgh, who published Mineral Kingdom,’ in 1789; a day, and of practical utility, as containing the best account of the coal strata. In his preface he misrepresents Hutton’s theory altogether, and charges him with considering all rocks to be lavas of different colours and structure ; and also with ‘warping everything to Support the eternity of the world.’+ He descants on the pernicious influence of such ‘ Some drill and bore * The solid earth, and from the strata there Extract a register, by which we learn, 15 at leit, and revealed its date To Moses, was mistaken in its age,’ The Task. Book iii. § The Garden? 577. VOL. I, G 82 KIRWAN—DE LUC. re. ay sceptical notions, as leading to downright infidelity and atheism, ‘and as being nothing less than to depose the Almighty Creator of the universe from his office.’* Kirwan—De Luc.—Kirwan, president of the Royal Academy: of Dublin, a chemist and mineralogist of some merit, but who possessed much greater authority in the scientific world than he was entitled by his talents to enjoy, said, in the introduction to his ‘ Geological Essays, 1799,’ ‘that sound geology graduated into religion, and was required to dispel certain systems of atheism or infidelity, of which they had had recent experience. + He was an uncompromising de- fender of the aqueous theory of all rocks, and was scarcely surpassed by Burnet and Whiston, in his desire to adduce the Mosaic writings in confirmation of his opinions. De Lue, in the preliminary discourse to his Treatise on Geology t says, ‘the weapons have been changed by which revealed religion is attacked; it is now assailed by geology, and the knowledge of this science has become essential to theologians.’ He imputes the failure of former geological systems to their having been anti-Mosaical, and directed against a ‘sublime tradition.’ These and similar imputa- tions, reiterated in the works of De Luc, seem to have been taken for granted by some modern writers: it is therefore necessary to state, in justice to the numerous geologists of different nations, whose works have been considered, that none of them were guilty of endeavouring, by arguments drawn from physics, to invalidate scriptural tenets. On the contrary, the majority of those who were fortunate enough ‘to discover the true causes of things,’ rarely deserved another part of the poet’s panegyric, ‘ Atque metus ommes subjecit pedibus. The caution, and even timid reserve, of many eminent Italian authors of the earlier period is very apparent; and there can hardly be a doubt, that they sub- scribed to certain dogmas, and particularly to the first diluvian theory, out of deference to popular prejudices, rather than from conviction. If they were guilty of dissimulation, we may feel regret, but must not blame their want of moral courage, reserving rather our condemnation for the intole- * P, 59. + Introd. p. 2. ¢ London, 1809. ald ate Dy whi gedlop, enti elated Cu. IV.] PLAYFAIR’S DEFENCE OF HUTTON. 83 rance of the times, and that inquisitorial power which forced Galileo to abjure, and the two Jesuits to disclaim the theory of Newton.* Hutton answered Kirwan’s attacks with great warmth, and with the indignation justly excited by unmerited reproach. ‘He had always displayed,’ says Playfair, ‘the utmost dis- position to admire the beneficent design manifested in the structure of the world; and he contemplated with delight those parts of his theory which made the greatest additions to our knowledge of final causes.’ We may say with equal truth, that in no scientific works in our language can more eloquent passages be found, concerning the fitness, harmony, and grandeur of all parts of the creation, than in those of Playfair. They are evidently the unaffected expressions of a mind, which contemplated the study of nature, as best calculated to elevate our conceptions of the attributes of the First Cause. At any other time the force and elegance of Playfair’s style must have insured popularity to the Hutto- nian doctrines; but by a singular coincidence, Neptunianism and orthodoxy were now associated in the same creed ; and the tide of prejudice ran so strong, that the majority were carried far away into the chaotic fluid, and other cosmological inventions of Werner. These fictions the Saxon professor had borrowed with little modification, and without any im- provement, from his predecessors. They had not the smallest foundation either in Scripture or in common sense, and were probably approved of by many as being so ideal * In a most able article, by Mr. Congregation; and the late Cardinal Drinkwater, on the ‘ Life of Galileo,’ i0zzi published in the ‘ Library of Useful Knowledge,’ it is stated that both Gali- this scandal] from the seat SS) He: [o) N N an i) M nm D oO ° MH an [=a © T|R © ° we ® Q S ° fe) had been taught in the Sapienza, and all Catholic universities in Europe (with the exception, I am told, of Sala- sured in the same year, by Professor Searpellini, at Rome, that Pius VII, a pontiff distinguished for his love of crees of the church, to use the term hypothesis, instead of theor ry. They edicts against Galileo and the Coper- now speak of the Copernican th ory. Op nican system. He had assembled the G 2 84 SMITH’S MAP OF ENGLAND. [Cu. IV and unsubstantial, that they could never come into violent collision with any preconceived opinions. According to De Lue, the first essential distinction to be made between the various phenomena exhibited on the surface of the earth was, to determine which were the results of causes still in action, and which had been produced by causes that had ceased to act. The form and composition of the mass of our continents, he said, and their existence above the level of the sea, must be ascribed to causes no longer in action. These continents emerged, at no very remote period, on the sudden retreat of the ocean, the waters of which made their way into subterranean caverns. The formation of the rocks which enter into the crust of the earth began with the precipitation of granite from a primordial liquid, after which other strata containing the remains of organised bodies were deposited, till at last the present sea remained as the residuum of the primordial liquid, and no longer continued to produce mineral strata.* William Smith, 1790.—While the tenets of the rival schools of Freyberg and Edinburgh were warmly espoused by devoted partisans, the labours of an individual, unassisted by the ad- vantages of wealth or station in society were almost unheeded. Mr. William Smith, an English surveyor, published his ‘Tabular View of the British Strata’ in 1790, wherein he proposed a classification of the secondary formations in the West of England. Although he had not communicated with Werner, it appeared by this work that he had arrived at the same views respecting the laws of superposition of stratified rocks; that he was aware that the order of succession of different groups was never inverted; and that they might be identified at very distant points by their peculiar organised fossils. From the time of the appearance of the ‘ Tabular View,’ the author laboured to construct a geological map of the whole of England; and with the greatest disinterestedness of mind, communicated the results of his investigations to all who desired information, giving such publicity to his original views, as to enable his contemporaries almost to compete * Elementary Treatise on Geology. London, 1809. Translated by De la Fite. Cu. IV.] NEW SCHOOL OF GEOLOGY. 85 with him in the race. The execution of his map was com- pleted in 1815, and remains a lasting monument of original talent and extraordinary perseverance; for he had explored the whole country on foot without the guidance of previous observers, or the aid of fellow-labourers, and had succeeded in throwing into natural divisions the whole complicated series of British rocks. D’Aubuisson, a distinguished pupil of Werner, paid a just tribute of praise to this remarkable performance, observing, that ‘what many celebrated mineralo- gists had only accomplished for a small part of Germany in the course of half a century, had been effected by a single individual for the whole of England.’ * Werner invented a new language to express his divisions of rocks, and some of his technical ternis, such as greywacke, gneiss, and others, passed current in every country in Europe. Smith adopted for the most part English provincial terms, often of barbarous sound, such as gault, cornbrash, clunch clay; and affixed them to subdivisions of the British series. Many of these still retain their place in our scientific classifi- cations and attest his priority of arrangement. MODERN PROGRESS OF GEOLOGY. The contention of the rival factions of the Vulcanists and Neptunists had been carried to such a height, that these names had become terms of reproach; and the two parties had been less occupied in searching for truth, than for such arguments as might strengthen their own cause or serve to annoy their antagonists. A new school at last arose, which professed the strictest neutrality, and the utmost indifference to the systems of Werner and Hutton, and which resolved diligently to devote its labours to observation. The reac- tion, provoked by the intemperance of the conflicting parties, now produced a tendency to extreme caution. Speculative views were discountenanced, and, through fear of exposing themselves to the suspicion of a bias towards the dogmas of a party, some geologists became anxious to entertain no opinion whatever on the causes of phenomena, and were * See Dr. Fitton’s Memoir, before cited, p. 57. 86 GEOLOGICAL SOCIETY OF LONDON. [Cu. Iv, inclined to scepticism even where the conclusions deducible from observed facts scarcely admitted of reasonable doubt, Geological Society of London.—But although the reluctance to theorise was carried somewhat to excess, no measure could be more salutary at such a moment than a suspension of aj] attempts to form what were termed ‘theories of the earth,’ A great body of new data were required; and the Geological Society of London, founded in 1807, conduced greatly to the attainment of this desirable end. To multiply and record observations, and patiently to await the result at some future period, was the object proposed by them ; and it was their favourite maxim that the time was not yet come fora general system of geology, but that all must be content for many years to be exclusively engaged in furnishing materials for future generalisations. By acting up to these principles with consistency, they in a few years disarmed all prejudice, and rescued the science from the imputation of being a dangerous, or at best but a visionary pursuit. A distinguished modern writer has with truth remarked, that the advancement of three of the main divisions of geo- logical enquiry have, during the last half century, been pro- moted successively by three different nations of Europe—the Germans, the English, and the French.*. We have seen that the systematic study of what may be called mineralogical geology had its origin and chief point of activity in Germany, where Werner first described with precision the mineral characters of rocks. The classification of the secondary formations, each marked by their peculiar fossils, belongs, in a great measure, to Hngland, where the labours before alluded to of Smith, and those of the most active members of the Geological Society of London, were steadily directed to these objects. The foundation of the third branch, that relating to the tertiary formations, was laid in France by the splendid work of Cuvier and Brogniart, published in 1808, ‘On the Mineral Geography and Organic Remains of the Neighbour- hood of Paris.’ : We may still trace, in the language of the science and our present methods of arrangement, the various countries where * Whewell, British Critic, No. xvii, p. 187. 1831. | ) | | Cx. IV.] STUDY OF ORGANIC REMAINS. 87 the growth of these several departments of geology was at different times promoted. Many names of simple minerals and rocks remain to this day German; while the Huropean divisions of the secondary strata are in great part English, and are, indeed, often founded too exclusively on English types. Lastly, the subdivisions first established in the Paris basin have served as normal groups to which other tertiary deposits throughout Hurope have been compared, even in cases where this standard was wholly inapplicable. No period could have been more fortunate for the discovery, in the immediate neighbourhood of Paris, of a rich store of well-preserved fossils, than the commencement of the present century; for at no former era had Natural History been cultivated with such enthusiasm in the French metropolis. The labours of Cuvier in comparative osteology, and of La- marck in recent and fossil shells, had raised these departments of study to a rank of which they had never previously been deemed susceptible. Their investigations had eventually a powerful effect in dispelling the illusion which had long prevailed concerning the absence of analogy between the ancient and modern state of our planet. A close comparison of the recent and fossil species, and the inferences drawn in regard to their habits, accustomed the geologist to contem- plate the earth as having been at successive periods the dwelling-place of animals and plants of different races, some terrestrial, and others aquatic—some fitted to live in seas, others in the waters of lakes andrivers. By the consideration of these topics, the mind was slowly and insensibly withdrawn from imaginary pictures of catastrophes and chaotic confu- sion, such as haunted the imagination of the early cosmogo- nists. Numerous proofs were discovered of the tranquil deposition of sedimentary matter, and the slow development of organic life. If many writers, and Cuvier himself in the number, still continued to maintain, that ‘the thread of induc- tion was broken,’ * yet, in reasoning by the strict rules of induction from recent to fossil species, they in a great measure disclaimed the dogma which in theory they professed. The adoption of the same generic, and, in some cases, even of the * Discours sur les Révolutions de la mer. 88 MODERN PROGRESS OF GEOLOGY. [Cu. Iv, same specific, names for the exuvie of fossil animals and theip living analogues, was an important step towards familiarising the mind with the idea of the identity and unity of the system in distant eras. It was an acknowledgment, as it were, that part at least of the ancient memorials of nature were written in a living language. The growing importance, then, of the natural history of organic remains may be pointed out as the characteristic feature of the progress of the science during the present century. This branch of knowledge has already become an instrument of great utility in geological classifi- cation, and is continuing daily to unfold new data for grand and enlarged views respecting the former changes of the earth. | When we compare the result of observations in the last eighty years with those of the three preceding centuries, we cannot but look forward with the most sanguine expectations to the degree of excellence to which geology may be carried, even by the labours of the present generation. Never, perhaps, did any science, with the exception of astronomy, unfold, in an equally brief period, so many novel and unexpected truths, and overturn so many preconceived opinions. The senses had for ages declared the earth to be at rest, until the astronomer taught that it was carried through space with inconceivable rapidity. In like manner was the surface of this planet regarded as having remained unaltered since its creation, until the geologist proved that it had been the theatre of reiterated change, and was still the subject of slow but never- ending fluctuations. The discovery of other systems in the boundless regions of space was the triumph of astronomy; to trace the same system through various transformations—to behold it at successive eras adorned with different hills and valleys, lakes and seas, and peopled with new inhabitants, was the delightful meed of geological research. By the geometer were measured the regions of space, and the relative distances _ of the heavenly bodies ;—by the geologist myriads of ages were reckoned, not by arithmetical computation, but by 4 train of physical events—a succession of phenomena in the animate and inanimate worlds—signs which convey to our ronowe \ceiratl s plu ereatiil, eat? xt neve Cu. IV.] MODERN PROGRESS OF GEOLOGY. 89 minds more definite ideas than figures can do of the immensity of time. Whether our investigation of the earth’s history and structure will eventually be productive of as great practical benefits to mankind as a knowledge of the distant heavens, must remain for the decision of posterity. It was not till astronomy had been enriched by the observations of many centuries, and had made its way against popular prejudices to the establishment of a sound theory, that its application to the useful arts was most conspicuous. The cultivation of geology began at a later period ; and in every step which it has hitherto made towards sound theoretical principles, it has had to contend against more violent prepossessions. The practical advantages already derived from it have not been inconsiderable ; but our generalisations are yet imper- fect, and they who come after us may be expected to reap the most valuable fruits of our labour. Meanwhile the charm of first discovery is our own; and, as we explore this mag- nificent field of enquiry, the sentiment of a great historian of our times may continually be present to our minds, that ‘he who calls what has vanished back again into being, enjoys a bliss like that of creating.’* * Niebuhr’s Hist. of Rome, vol. i. p. 5. Hare and Thirlwall’s translation. CHAPTER V. PREJUDICES WHICH HAVE RETARDED THE PROGRESS OF GHOLOGY, PREPOSSESSIONS IN REGARD TO THE DURATION OF PAST’ TIME—PREJUDICES THE CT: HAVE PRODUCED THE FORMER CHANGES OF THE EARTH'S SURFACE, CONSI- DERED. Ir we reflect on the history of the progress of geology, as explained in the preceding chapters, we perceive that there have been great fluctuations of opinion respecting the nature of the causes to which all former changes of the earth’s surface are referable. The first observers conceived the monuments which the geologist endeavours to decipher to relate to an original state of the earth, or to a period when there were causes in activity, distinct, in kind and degree, from those now constituting the economy of nature. These views were gradually modified, and some of them entirely abandoned in proportion as observations were multiplied, and the signs of former mutations were skilfully interpreted. Many appearances, which had for a long time been regarded as indicating mysterious and extraordinary agency, were finally recognised as the necessary result of the laws now governing the material world; and the discovery of this unlooked-for conformity has = length induced some philo- sophers to infer, that, during the ages contemplated in geology, there has never bean any interruption to the agency of the same uniform laws of change. The same assemblage of general causes, they conceive, may have been Hs a @ Joortn wg Cu. V.] VIEWS ON THE DURATION OF PAST TIME. 91 sufficient to produce, by their various combinations, the endless diversity of effects, of which the shell of the earth has preserved the memorials; and, consistently with these principles, the recurrence of analogous changes is expected by them in time to come. Whether we coincide or not in this doctrine, we must admit that the gradual progress of opinion concerning the succession of phenomena in very remote eras, resembles, in a singular manner, that which has accompanied the growing intelligence of every people, in regard to the economy of nature in their own times. In an early state of advancement, when a greater number of natural appearances are unintel- ligible, an eclipse, an earthquake, a flood, or the approach of a comet, with many other occurrences afterwards found to belong to the regular course of events, are regarded as prodigies. 'The same delusion prevails as to moral pheno- mena, and many of these are ascribed to the intervention of demons, ghosts, witches, and other immaterial and supernatural agents. By degrees, many of the enigmas of the moral and physical world are explained, and, instead of being due to extrinsic and irregular causes, they are found to depend on fixed and invariable laws. The philosopher at last becomes convinced of the undeviating uniformity of secondary causes; and, guided by his faith in this principle, he determines the probability of accounts transmitted to him of former occurrences, and often rejects the fabulous tales of former times, on the ground of their being irreconcilable with the experience of more enlightened ages. Prepossessions in regard to the duration of past time.—As a belief in the want of conformity in the causes by which the earth’s crust has been modified in ancient and modern periods was, for a long time, universally prevalent, and that, too, amongst men who were convinced that the order of nature had been uniform for the last several thousand years, every circumstance which could have influenced their minds and given an undue bias to their opinions deserves particular attention. Now the reader may easily satisfy himself, that, however undeviating the course of nature may have been from the earliest epochs, it was impossible for the first 92 PREJUDICES WHICH RETARD [Cu. V, cultivators of geology to come to such a conclusion, go long as they were under a delusion as to the age of the worlg and the date of the first creation of animate beings. Howeyey fantastical some theories of the sixteenth century may now appear to us,—however unworthy of men of great talent and sound judgment,—we may rest assured that, if the same misconception now prevailed in regard to the memorials of human transactions, it would give rise to a similar train of absurdities. Let us imagine, for example, that Champollion, and the French and Tuscan literati when engaged in ex- ploring the antiquities of Egypt, had visited that country with a firm belief that the banks of the Nile weré never peopled by the human race before the beginning of the nine- teenth century, and that their faith in this dogma was as difficult to shake as the opinion of our ancestors, that the earth was never the abode of living beings until the creation of the present continents, and of the species now existing,— it is easy to perceive what extravagant systems they would frame, while under the influenice of this delusion, to account for the monuments discovered in Egypt. The sight of the pyramids, obelisks, colossal statues, and ruined temples, would fill them with such astonishment, that for a time they would be as men spell-bound—wholly incapable of reasoning with sobriety. They might incline at first to refer the con- struction of such stupendous works to some superhuman powers of a primeval world. A system might be invented resembling that so gravely advanced by Manetho, who relates that a dynasty of gods originally ruled in Egypt, of whom Vulcan, the first monarch, reigned nine thousand years; after whom came Hercules and other demigods, who were at last succeeded by human kings. When some fanciful speculations of this kind had amused their imaginations for a time, some vast repository of mum- mies would be discovered, and would immediately undeceive those antiquaries who enjoyed an opportunity of personally examining them ; but the prejudices of others at a distance; who were not eye-witnesses of the whole phenomena, would not be so easily overcome. The concurrent report of many travellers would, indeed, render it necessary for them to Cu. V.] THE PROGRESS OF GEOLOGY. 93 v0 accommodate ancient theories to some of the new facts, and much wit and ingenuity would be required to modify and defend their old positions. Hach new invention would violate a greater number of known analogies ; for if a theory be required to embrace some false principle, it becomes more visionary in proportion as facts are multiplied, as would be the case if geometers were now required to form an astro- nomical system on the assumption of the immobility of the earth. Amongst other fanciful conjectures concerning the history of Egypt, we may suppose some of the following to be started. ‘As the banks of the Nile have been so recently colonized for the first time, the curious substances called mummies could never in reality have belonged to men. They may have been generated by some plastic virtue residing in the interior of the earth, or they may be abortions of Nature produced by her incipient efforts in the work of creation. For if deformed beings are sometimes born even now, when the scheme of the universe is fully developed, many more may have been “ sent before their time, scarce half made up,” when the planet itself was in the embryo state. But if these notions appear to derogate from the perfection of the Divine attributes, and if these mummies be in all their parts true representations of the human form, may we not refer them to the future rather than the past >—May we not be looking into the womb of Nature, and not her grave? May not these images be like the shades of the unborn in Virgil’s Elysium—the archetypes of men not yet called into existence?’ These speculations, if advocated by eloquent writers, would not fail to attract many zealous votaries, for they would relieve men from the painful necessity of renouncing precon- ceived opinions. Incredible as such scepticism may appear, it has been rivalled by many systems of the sixteenth and seven- teenth centuries, and among others by that of the learned Falloppio, as we have seen (p. 33), who regarded the tusks of fossil elephants as earthy concretions, and the pottery or fragments of vases in the Monte Testaceo, near Rome, as works of nature, and not of art. But when one generation had passed away, and another, not compromised to the 94 PREJUDICES WHICH RETARD [Cu, V, support of antiquated dogmas, had succeeded, they woulq review the evidence afforded by mummies more impartially, and would no longer controvert the preliminary question, that human beings had lived in Egypt before the nineteenth century: so that when a hundred years perhaps had been lost, the industry and talents of the philosopher would be at last directed to the elucidation of points of real historica] importance. But the above arguments are aimed against one only of many prejudices with which the earlier geologists had to contend. Even when they conceded that the earth had been peopled with animate beings at an earlier period than was at first supposed, they had no conception that the quantity of time bore so great a proportion to the historical era as is now generally conceded. How fatal every error as to the quantity of time must prove to the introduction of rational views concerning the state of things in former ages, may be conceived by supposing the annals of the civil and military transactions of a great nation to be perused under the im- pression that they occurred in a period of one hundred instead of two thousand years. Such a portion of history would immediately assume the air of a romance; the events would seem devoid of credibility, and inconsistent with the present course of human affairs. A crowd of incidents would follow each other in thick succession. Armies and fleets would appear to be assembled only to be destroyed, and cities built merely to fall in ruins. There would be the most violent transitions from foreign or intestine war to periods of pro- found peace, and the works effected during the years of disorder or tranquillity would appear alike superhuman in magnitude. He who should study the monuments of the natural world under the influence of a similar infatuation, must draw @ no less exaggerated picture of the energy and violence of causes, and must experience the same insurmountable diffi- culty in reconciling the former and present state of nature. If we could behold in one view all the voleanic cones throw? up in Iceland, Italy, Sicily, and other parts of Europé, during the last five thousand years, and could see the lavas Cu. V.] THE PROGRESS OF GEOLOGY. 95 which have flowed during the same period ; the dislocations, subsidences, and elevations caused during earthquakes ; the lands added to various deltas, or devoured by the sea, to- gether with the effects of devastation by floods, and imagine that all these events had happened in one year, we must form most exalted ideas of the activity of the agents, and the suddenness of the revolutions. Were an equal amount of change to pass before our eyes in the next year, could we avoid the conclusion that some great crisis of nature was at hand? If geologists, therefore, have misinterpreted the signs of a succession of events, so as to conclude that cen- turies were implied where the characters imported thousands of years, and thousands of years where the language of Nature signified millions, they could not, if they reasoned logically from such false premises, come to any other con- clusion than that the system of the natural world had undeyr- gone a complete revolution. We should be warranted in ascribing the erection of the great pyramid to superhuman power, if we were convinced that it was raised in one day ; and if we imagine, in the same manner, a continent or mountain-chain to have been ele- vated, during an equally small fraction of the time which was really occupied in upheaving it, we might then be justified in inferring, that the subterranean movements were once far more energetic than in our own times. We know that during one earthquake the coast of Chili may be raised for a hundred miles to the average height of about three feet. A repetition of two thousand shocks, of equal violence, might produce a mountain-chain one hundred miles long, and six thousand feet high. Now, should one or two only of these convulsions happen in a century, it would be #consistent with the order of events experienced by the Chilians from the earliest times: but if the whole of them were to occur in the next hundred years, the entire district must be depopu- lated, scarcely any animals or plants could survive, and the surface would be one confused heap of ruin and desolation. One consequence of undervaluing greatly the quantity of past time, is the apparent coincidence which it occasions of events necessarily disconnected, or which are so unusual, 96 PREJUDICES WHICH RETARD [Cu, VY. that it would be inconsistent with all calculation of chances to suppose them to happen at one and the same time, When the unlooked-for association of such rare phenomena jg witnessed in the present course of nature, it scarcely ever fails to excite a suspicion of the preternatural in those mindg which are not firmly convinced of the uniform agency of secondary causes;—as if the death of some individual jp whose fate they are interested happens to be accompanied by the appearance of a luminous meteor, or a comet, or the shock of an earthquake. It would be only necessary to multiply such coincidences indefinitely, and the mind of every philosopher would be disturbed. Now it would be difficult to exaggerate the number of physical events, many of them most rare and unconnected in their nature, which were imagined by the Woodwardian hypothesis to have happened in the course of a few months: and numerous other examples might be found of popular geological theories, which require us to imagine that a long succession of events happened in a brief and almost momentary period. Another liability to error, very nearly allied to the former, arises from the frequent contact of geological monuments referring to very distant periods of time. We often behold, at one glance, the effects of causes which have acted at times | incalculably remote, and yet there may be no striking cir- cumstances to mark the occurrence of a great chasm in the chronological series of Nature’s archives. In the vast interval of time which may really have elapsed between the results of operations thus compared, the physical condition of the earth may, by slow and insensible modifications, have become entirely altered; one or more races of organic beings may have passed away, and yet have left behind, in the particular region under contemplation, no trace of their existence. To a mind unconscious of these intermediate events, the passage from one state of things to another must appear s0 violent, that the idea of revolutions in the system inevitably suggests itself. The imagination is as much perplexed by the deception, as it might be if two distant points in space were suddenly brought into immediate proximity. Let us suppose, for a moment, that a philosopher should lie down Cu. V.] THE PROGRESS OF GEOLOGY. 97 to sleep in some arctic wilderness, and then be transferred by a power, such as we read of in tales of enchantment, to a valley in a tropical country, where, on awaking, he might find himself surrounded by birds of brilliant plumage, and all the luxuriance of animal and vegetable forms of which Nature is so prodigal in those regions. The most reasonable supposition, perhaps, which he could make, if by the necro- mancer’s art he were placed in such a situation, would be, that he was dreaming; and if a geologist form theories under a similar delusion, we cannot expect him to preserve more consistency in his speculations than in the train of ideas in an ordinary dream. It may afford, perhaps, a more lively illustration of the principle here insisted upon, if I recall to the reader’s recol- lection the legend of the Seven Sleepers. The scene of that popular fable was placed in the two centuries which elapsed between the reign of the emperor Decius and the death of Theodosius the younger. In that interval of time (between the years 249 and 450 of our era) the union of the Roman empire had been dissolved, and some of its fairest provinces overrun by the barbarians of the north. The seat of govern- ment had passed from Rome to Constantinople, and the throne from a pagan persecutor to a succession of Christian and orthodox princes. The genius of the empire had been humbled in the dust, and the altars of Diana and Hercules were on the point of being transferred to Catholic saints and martyrs. The legend relates, ‘that when Decius was still persecuting the Christians, seven noble youths of Ephesus concealed themselves in a spacious cavern in the side of an adjacent mountain, where they were doomed to perish by the tyrant, who gave orders that the entrance should be firmly secured with a pile of huge stones. They immediately fell into a deep slumber, which was miraculously prolonged, with- out injuring the powers of life, during a period of 187 years. At the end of that time the slaves of Adolius, to whom the inheritance of the mountain had descended, removed the stones to supply materials for some rustic edifice: the hight of the sun darted into the cavern, and the seven sleepers were permitted to awake. After a slumber, as they thought, VOL. I. H 98 PREJUDICES WHICH HAVE RETARDED [Cx. V, of a few hours, they were pressed by the calls of hunger, ang resolved that Jamblichus, one of their number, should secretly return to the city to purchase bread for the use of his com- panions. The youth could no longer recognise the once familiar aspect of his native country, and his surprise was increased by the appearance of a large cross triumphantly erected over the principal gate of Ephesus. His singular dress and obsolete language confounded the baker, to whom he offered an ancient medal of Decius as the current coin of the empire; and Jamblichus, on the suspicion of a secret treasure, was dragged before the judge. Their mutual enquiries produced the amazing discovery, that two centuries were almost elapsed since Jamblichus and his friends had escaped from the rage of a pagan tyrant.’ * This legend was received as authentic throughout the Christian world before the end of the sixth century, and was afterwards introduced by Mahomet as a divine revelation into the Koran, and from hence was adopted and adorned by all the nations from Bengal to Africa who professed the Maho- metan faith. Some vestiges even of a similar tradition have been discovered in Scandinavia. ‘This easy and universal belief,’ observes the philosophical historian of the Decline and Fall, ‘so expressive of the sense of mankind, may be ascribed to the genuine merit of the fable itself. We imperceptibly advance from youth to age, without observing the gradual, but incessant, change of human affairs; and even, in our larger experience of history, the imagination is accustomed, by a perpetual series of causes and effects, to unite the most distant revolutions. But if the interval between two memo- rable eras could be instantly annihilated ; if it were possible, after a momentary slumber of two hundred years, to display the new world to the eyes of a spectator who still retained @ lively and recent impression of the old, his surprise and his yeflections would furnish the pleasing subject of a philoso- phical romance.’+ Prejudices arising from our peculiar position as inhabitants of the land.—The sources of prejudice hitherto considered * Gibbon, Decline and Fall, chap. xxxiil. + Id. Ibid. Cu. V.] THE PROGRESS OF GEOLOGY. 99 may be deemed peculiar for the most part to the infancy of the science, but others are common to the first cultivators of geology and to ourselves, and are all singularly calculated to produce the same deception, and to strengthen our belief that the course of nature in the earlier ages differed widely from _that now established. Although these circumstances cannot be fully explained without assuming some things as proved, which it has been my object in another treatise to demon- strate,* it may be well to allude to them briefly in this place. The first and greatest difficulty, then, consists in an ha- bitual unconsciousness that our position as observers is essen- tially unfavourable, when we endeavour to estimate the nature and magnitude of the changes now in progress. In consequence of our inattention to this subject, we are liable to serious mistakes in contrasting the present with former states of the globe. As dwellers on the land, we inhabit about a fourth part of the surface ; and that portion is almost exclusively a theatre of decay, and not of reproduction. We know, indeed, that new deposits are annually formed in seas and lakes, and that every year some new igneous rocks are our minds by the aid of reflection, it requires an effort both of the reason and the imagination to appreciate duly their importance. It is, therefore, not surprising that we estimate very imperfectly the result of operations thus invisible to us ; and that, when analogous results of former epochs are pre- sented to our inspection, we cann ot immediately recognise the analogy. He who has observed the quarrying of stone from a rock, and has seen it shipped for some distant port, and then endeavours to conceive what kind of edifice will be raised by the materials, is in the same predicament as a geo- logist, who, while he is confined to the land, sees the decom- position of rocks, and the to the sea, and then ende Prejudices arising from our not seeing subterranean changes. —Nor is his position less unfavourable when, beholding a * Elements of Geology, 6th edit. 1865, H2 100 PREJUDICES WHICH HAVE RETARDED. [Cu. V, volcanic eruption, he tries to conceive what changes the column of lava has produced, in its passage upwards, on the intersected strata; or what form the melted matter may ag. sume at great depths on cooling; or what may be the extent of the subterranean rivers and reservoirs of liquid matter fay beneath the surface. It should, therefore, be remembered, that the task imposed on those who study the earth’s history requires no ordinary share of discretion ; for we are precluded from collating the corresponding parts of the system of things as it exists now, and as it existed at former periods. If we were inhabitants of another element—if the great ocean were our domain, instead of the narrow limits of the land, our difficulties would be considerably lessened; while, on the other hand, there can be little doubt, although the reader may, perhaps, smile at the bare suggestion of such an idea, that an amphibious being, who should possess our faculties, would still more easily arrive at sound theoretical opinions in geology, since he might behold, on the one hand, the de- composition of rocks in the atmosphere, or the transportation of matter by running water; and, on the other, examine the deposition of sediment in the sea, and the imbedding of ani-. mal and vegetable remains in new strata. He might ascer- tain, by direct observation, the action of a mountain torrent, as well as of a marine current; might compare the products of volcanos poured out upon the land with those ejected be- neath the waters; and might mark, on the one hand, the growth of the forest, and, on the other, that of the coral reef. Yet, even with these advantages, he would be liable to fall into the greatest errors, when endeavouring to reason on rocks of subterranean origin. He would seek in vain, within the sphere of his observation, for any direct analogy to the process of their formation, and would therefore be in danger of attributing them, wherever they are upraised to view, to some ‘ primeval state of nature.’ But if we may be allowed so far to indulge the imagination, as to suppose a being entirely confined to the nether wore” some ‘dusky melancholy sprite,’ like Umbriel, who could ‘flit on sooty pinions to the central earth,’ but who was neve permitted to ‘sully the fair face of light,’ and emerge into Cu. V.] THE PROGRESS OF GEOLOGY. 101 the regions of water and of air; and if this being should busy ° himself in investigating the structure of the globe, he might frame theories the exact converse of those usually adopted by human philosophers. He might infer that the stratified rocks, containing shells and other organic remains, were the oldest of created things, belonging to some original and nas- cent state of the planet. ‘Of these masses,’ he might say, ‘whether they consist of loose incoherent sand, soft clay, or solid stone, none have been formed in modern times. Every year some part of them are broken and shattered by earth- quakes, or melted by volcanic fire; and when they cool down slowly from a state of fusion, they assume a new and more crystalline form, no longer exhibiting that stratified disposi- tion and those curious impressions and fantastic markings, by which they were previously characterised. This process cannot have been carried on for an indefinite time, for in that ease all the stratified rocks would long ere this have been fused and crystallised. It is therefore probable that the whole planet once consisted of these mysterious and curiously bedded formations at a time when the volcanic fire had not yet been brought into activity. Since that period there seems to have been a gradual development of heat; and this aug- mentation we may expect to continue till the whole globe shall be in a state of fluidity, or shall consist, in those parts which are not melted, of volcanic and crystalline rocks.’ Such might be the system of the Gnome at the very time that the followers of Leibnitz, reasoning on what they saw on the outer surface, might be teaching the opposite doctrine of gradual refrigeration, and averring that the earth had be- gun its career as a fiery comet, and might be destined here- after to become a frozen mass. The tenets of the schools of the nether and of the upper world would be directly opposed to each other, for both would partake of the prejudices ine- vitably resulting from the continual contemplation of one class of phenomena to the exclusion of another. Man observes the annual decomposition of crystalline and igneous rocks, and may sometimes see their conversion into stratified deposits ; but he cannot witness the reconversion of the sedi- mentary into the crystalline by subterranean fire. He is in 102 ASSUMED DISCORDANCE OF [Cu. V, ' the habit of regarding all the sedimentary rocks as more recent than the unstratified, for the same reason that we may suppose him to fall into the opposite error if he saw the origin of the igneous class only. It was not an impossible contingency, that astronomers might have been placed at some period in a situation much resembling that in which the geologist seems to stand at present. If the Italians, for example, in the early part of the twelfth century, had discovered at Amalfi, instead of the pandects of Justinian, some ancient manuscripts filled with | _astronomical observations relating to a period of three thou- sand years, and made by some ancient geometers who pos- sessed optical instruments as perfect as any in modern Hurope, they would probably, on consulting these memorials, have come to a conclusion that there had been a great revo- lution in the solar and sidereal systems. ‘Many primary and secondary planets,’ they might say, ‘are enumerated in these tables, which exist no longer. Their positions are assigned with such precision that we may assure ourselves that there is nothing in their place at present but the blue ether. Where one star is visible to us, these doeuments represent several thousands. Some of those which are now single consisted then of two separate bodies, often distinguished by different colours, and revolving periodically round a common centre of gravity. There is nothing analogous to them in the universe at present ; for they were neither fixed stars nor planets, but seem to have stood in the mutual relation of sun and planet to each other. We must conclude, therefore, that there has occurred, at no distant period, a tremendous ¢a- tastrophe, whereby thousands of worlds have been annihilated at once, and some heavenly bodies absorbed into the sub- stance of others.’ When such doctrines had prevailed for ages, the discovery of some of the worlds, supposed to have been lost (the satel- lites of Jupiter, for example), by aid of the first rude telescope invented after the revival of science, would not dissipate the delusion, for the whole burden of proof would now be throw? on those who insisted on the stability of the system from 4 remote period, and these philosophers would be required t0 Cu. V.] ANCIENT AND MODERN CAUSES. 103 demonstrate the existence of all the worlds said to have been annihilated. Such popular prejudices would be most unfavourable to the advancement of astronomy ; for, instead of persevering in the attempt to improve their instruments, and laboriously to make and record observations, the greater number would de- spair of verifying the continued existence of the heavenly bodies not visible to the naked eye. Instead of confessing the extent of their ignorance, and striving to remove it by bringing to light new facts, they would indulge in the more easy and indolent employment of framing imaginary theories concerning catastrophes and mighty revolutions in the system of the universe. For more than two centuries the shelly strata of the Subappenine hills afforded matter of speculation to the early geologists of Italy, and few of them had any suspicion that similar deposits were then forming in the neighbouring sea. They were as unconscious of the continued action of causes still producing similar effects, as the astronomers, in the case above supposed, of the existence of certain heavenly bodies still giving and reflecting light, and performing their movements as of old. Some imagined that the strata, so rich in organic remains, instead of being due to secondary agents, had been so created in the beginning of things by the fiat of the Almighty. Others, as we have seen, ascribed the imbedded fossil bodies to some plastic power which resided in the earth in the early ages of the world. In what manner were these dogmas at length exploded? The fossil relics were carefully compared with their living analogues, and all doubts as to their organic origin were eventually dispelled. So, also, in regard to the nature of the containing beds of mud, sand, and limestone: those parts of the bottom of the sea were examined where shells are now becoming annually entombed in new deposits. Donati explored the bed of the Adriatic, and found the closest resemblance between the strata there forming, and those which constituted hills above a thousand feet high in various parts of the Italian peninsula. He ascertained by dredging that living testacea were there grouped together in precisely the same manner 104 ASSUMED DISCORDANCE OF [Cu. V. as were their fossil analogues in the inland strata; ang while some of the recent shells of the Adriatic were becomin incrusted with calcareous rock, he observed that others had been newly buried in sand and clay, precisely as fossil shells occur in the Subapennine hills. This discovery of the iden- tity of modern and ancient submarine operations wags not made without the aid of artificial instruments, which, like the telescope, brought phenomena into view not otherwise within the sphere of human observation. In like manner, the volcanic rocks of the Vicentin had been studied in the beginning of the last century; but no eeologist suspected, before the time of Arduino, that these were composed of ancient submarine lavas. During many years of controversy, the popular opinion inclined to a belief that basalt and rocks of the same class had been precipi- tated from a chaotic fluid, or an ocean which rose at succes- Sive periods over the continents, charged with the com- ponent elements of the rocks in question. Few will now dispute that it would have been difficult to invent a theory more distant from the truth; yet we must cease to wonder that it gained so many proselytes, when we remember that its claims to probability arose partly from the very circum- stance of its confirming the assumed want of analogy between geological causes and those now in action. By what train of investigations were geologists induced at length to reject these views, and to assent to the igneous origin of the trap- pean formations? By an examination of volcanos now active, and by comparing their structure and the composition of their lavas with the ancient trap rocks. The establishment, from time to time, of numerous points of identification, drew at length from geologists a reluctant admission, that there was more correspondence between the condition of the globe at remote eras and now, and more uniformity in the laws which have regulated the changes of its surface, than they at first imagined. If, in this state of the science, they still despaired of reconciling every class of geological phenomena to the operations of ordinary causes, even by straining analogy to the utmost limits of credibility, we might have expected, at least, that the balance of proba- . wy act Cu. V.] ANCIENT AND MODERN CAUSES. 105 bility would now have been presumed to incline towards the ‘close analogy of the ancient and modern causes. But, after repeated experience of the failure of attempts to speculate on geological monuments, as belonging to a distinct order of things, new sects continued to persevere in the principles adopted by their predecessors. They still began, as each new problem presented itself, whether relating to the animate or inanimate world, to assume an original and dissimilar order of nature; and when at length they approximated, or entirely came round to an opposite opinion, it was always with the feeling, that they were conceding what they had been justified @ priori in deeming improbable. In a word, the same men who, as natural philosophers, would have been most incredulous respecting any extraordinary deviations from the known course of nature, if reported to have hap- pened in their own time, were equally disposed, as geologists, to expect the proofs of such deviations at every period of the past. I shall proceed in the following chapters to enumerate some of the principal difficulties still opposed to the theory of the uniform nature and energy of the causes which have worked successive changes in the crust of the earth, and in the condition of its living inhabitants. The discussion of so important a question on the present occasion may appear premature, but it is one which naturally arises out of a review of the former history of the science. It is, of course, impossible to enter into such speculative topics, without occasionally carrying the novice beyond his depth, and appealing to facts and conclusions with which he will be unacquainted, until he has studied some elementary work on geology, but it may be useful to excite his curiosity, and lead him to study such works by calling his attention at once to some of the principal points of controversy.* * Jn the earlier editions of this work, the crust of the earth. This I after- a fourth book was added on Geology wards (in 1838) expanded into a sepa- Proper, or Systematic Geology, con- rate publication called the Elements or taining an account of the former changes Manual of Geology, of which a sixth imate and inanimate creation, edition appeared, January 18665. brought to light by an examination of 106 CHAPTER VI. SUPPOSED INTENSITY OF AQUEOUS FORCES AT REMOTE PERIODS. INTENSITY OF AQUEOUS CAUSES—SLOW ACCUMULATION OF STRATA PROVED BY FOSSILS—-RATE OF DENUDATION CAN ONLY KEEP PACE WITH DEPOSITION —ERRATICS, AND ACTION OF I E—DELUGES, AND THE CAUSES TO WHICH THEY ARE REFERRED—SUPPOSED UNIVERSALITY OF ANCIENT DEPOSITS, INTENSITY OF AQUEOUS CAUsES.—The great problem alluded to at the close of the last chapter may thus be stated, whether the former changes of the earth made known to us by geology, resemble in kind and degree those now in daily progress. This question may be contemplated from several points of view, and it embraces among other subjects the enquiry, whether there are any grounds for the belief enter- tained by many, that the intensity both of aqueous and of igneous forces, in remote ages, far exceeded that which we witness in our own times. First, then, as to aqueous causes: it has been shown in our history of the science, that Woodward did not hesitate, in 1695, to teach that the entire mass of fossiliferous strata contained in the earth’s crust had been deposited in a few months ; and, consequently, as their mechanical and deriva- tive origin was already admitted, the reduction of rocky masses into mud, sand, and pebbles, the transportation of the same to a distance, and their accumulation elsewhere in regular strata, were all assumed to have taken place with a rapidity unparalleled in modern times. This doctrine was modified by degrees, in proportion as different classes of organic remains, such as shells, corals, and fossil plants, had been studied with attention. Analogy led every naturalist to assume, that each full-grown individual of the animal or Cx. VIL] INTENSITY OF AQUEOUS CAUSES. 107 vegetable kingdom, had required a certain number of days, months, or years for the attainment of maturity, and the per- petuation of its species by generation; and thus the first approach was made to the conception of a common standard of time, without which there are no means whatever of measuring the comparative rate at which any succession of events has taken place at two distinct periods. This standard consisted of the average duration of the lives of individuals of the same genera or families in the animal and vegetable kingdoms ; and the multitude of fossils dispersed through successive strata implied the continuance of the same species for many generations. At length the idea that species themselves had had a limited duration, arose out of the observed fact that sets of strata of different ages con- tained fossils of distinct species. Finally, the opinion became general, that in the course of ages, one assemblage of animals and plants had disappeared after another again and again, and new tribes had started into life to replace them. Denudation.—In addition to the proofs derived from organic remains, the forms of stratification led also, on a fuller in- vestigation, to the belief that sedimentary rocks had been slowly deposited; but it was still supposed that denudation, or the power of running water, and the waves and currents of the ocean, to strip off superior strata, and lay bare the rocks below, had formerly operated with an energy wholly unequalled in our times. These opinions were both illogical and inconsistent, because deposition and denudation are processes inseparably connected, and what is true of the rate of one of them, must be true of the rate of the other within very narrow limits, and the conveyance of solid matter to a particular region can only keep pace with its removal from another, so that the aggregate of sedimentary strata in the earth’s crust can never exceed in volume the amount of solid matter which has been ground down and washed away by rivers, waves, and currents. How vast then must be the spaces which this abstraction of matter has left vacant! how far exceeding in dimensions all the valleys, however nume- rous, and the hollows, however vast, which we can prove to have been cleared out by aqueous erosion! the evidences of 108 SUPPOSED FORMER INTENSITY (Cu. VI, the work of denudation are defective, because it is the nature of every destroying cause to obliterate the signs of its own agency; but the amount of reproduction in the form of sedi- mentary strata must always afford a true measure of the minimum of denudation which the earth’s surface has under. gone. It is no more than a minimum, because the materials of the earth’s crust in a multitude of cases have been broken up again and again and re-stratified, so that it is only the last of many forms through which they have past that ig now presented to our view. Erratics and ice-action.—Another phenomenon to which the ‘advocates of the excessive power of running water in times past have appealed, is the enormous size of the blocks called erratic, which lie scattered over the northern parts of Europe and North America. Unquestionably a large proportion of these blocks have been transported far from their original position, for between them and the parent rocks we now find, not unfrequently, deep seas and valleys intervening, or hills more than a thousand feet high. To explain the present situa- tion of such travelled fragments, a deluge of mud was imagined by some to have come from the north, bearing along with it sand, gravel, and stony fragments, some of them hundreds of tons in weight. This flood, in its transient passage over the continents, dispersed the boulders irregularly over hill, valley, and plain; or forced them alone over a surface of hard rock, so as to polish it and leave it indented with paral- lel scratches and grooves,—such markings as are still visible in the rocks of Scandinavia, Scotland, Canada, and many other countries. There can be no doubt that the myriads of angular and rounded blocks above alluded to, cannot have been borne along by ordinary rivers or marine currents, so great is their volume and weight, and so clear are the signs, in many places, of time having been occupied in their successive deposition ; for while some of them are buried in mud and sand, others are distributed at various depths through heaps of regularly stratified sand and eravel. No waves of the sea raised by earthquakes, nor the bursting of lakes dammed up for a time by landslips or by avalanches of snow, can account —— eo oo = E P # — | Cx. VI.J OF AQUEOUS CAUSES CONTROVERTED. 109 for the observed facts; but I shall endeavour to show, in the sequel,* that a combination of existing causes may have conveyed erratics into their present situations. The causes which will be referred to are, first, the carrying power of ice, combined with that of running water; and second, the upward movement of the bed of the sea, convert- ing it gradually into land. Without entering at present into any details respecting these causes, I may mention that the transportation of blocks by ice is now simultaneously in progress, not only in the arctic and antarctic regions, but in a part of the temperate latitudes, both of the northern and southern hemisphere, as, for example, on the coasts of Canada and Gulf of St. Lawrence, and also in Chili, Patagonia, and the island of South Georgia. In those regions the uneven bed of the ocean is becoming strewed over with ice-drifted fragments, which have either stranded on shoals, or been dropped in deep water by melting bergs. The entanglement of boulders in drift ice will also be shown to occur annually in North America, and these stones, when firmly frozen into ice, wander year after year from Labrador to the Lawrence, and reach points of the western hemisphere farther south than any part of Great Britain. The general absence of erratics in the warmer parts of the equatorial regions of Asia, Africa, and America, confirms the same views. As to the polishing and grooving of hard rocks, it has been ascertained that glaciers give rise to these effects when pushing forward sand, pebbles, and rocky fragments, and causing them to grate along the bottom. Nor can there be any reasonable doubt that icebergs, when they run aground on the floor of the ocean, must imprint similar marks upon it. It is unnecessary, therefore, to refer to deluges, or great oceanic waves, to explain the transportation of erratics to great distances. As to variations in the tides in past times, they can never have been sufficient to have imparted to marine currents, or to the waves breaking on a coast, a degree of force greatly exceeding that which they usually exert. When the excen- tricity of the earth’s orbit, of which more will be said in the * See also Elements of Geology, ch. 11, 12. 110 SUPPOSED FORMER INTENSITY [Cx. Vq, thirteenth chapter, is at or near its maximum, the rise of the solar tide will amount to two-and-a-half, instead of two feet ; but the increased power thus derived from solar attraction, may be neglected by a geologist, seeing that the, configuration of the land now produces differences in the height of the tides to the extent of fifty feet and upwards, instead of those few additional inches gained by proximity to the sun in the case above proposed. During the glacial period, which will be treated of in the ninth and following chapters, the quantity of ice was so great, as to enable it to exert a carrying power far beyond what it exerts at present, or in the ordinary and normal state of the globe. But such a development of the energy of ice recurring at distant intervals, and for limited periods, is not catastrophic, and is wholly unconnected with causes which might be supposed to operate in a nascent state of the planet. In regard also to ice, we must remember that its action on land is substituted for that of running water, The one becomes a mighty agent in transporting huge erra- tics, and in scoring, abrading, and polishing rocks; but mean- while the other is in abeyance. When, for example, the ancient Rhone glacier conveyed its moraines from the upper to the lower end of the Lake of Geneva, there was no ereat river, as there now is, forming a delta many miles in extent, and several hundred feet in depth, at the upper end of the lake. Deluges.—As deluges have been often alluded to (page 18, &c.), I shall say something of the causes which may be supposed to give rise to these grand movements of water. Geologists who believe that mountain-chains -have been thrown up suddenly at many successive epochs, imagine that the waters of the ocean may be raised by these convulsions, and then break in terrific waves upon the land, sweeping over whole continents, hollowing out valleys, and transporting sand, gravel, and erratics to great distances. The sudden rise of the Alps or Andes, it is said, may have produced a flood even subsequently to the time when the earth became the residence of man. But it seems strange that none of the writers who have indulged their imaginations in conjectures of this kind, should have ascribed a deluge to the sudden conversion of part of the unfathomable ocean into a shoa Cu. VI.] OF AQUEOUS CAUSES CONTROVERTED. 111 rather than to the rise of mountain-chains. In the latter case, the mountains themselves could do no more than displace a certain quantity of atmospheric air, whereas, the instanta- neous formation of the shoal would displace a vast body of water, which being heaved up to a great height might roll over and permanently submerge a large portion of a continent. Tf we restrict ourselves to combinations of causes at present known, it would seem that the two principal sources of extra- ordinary inundations are, first, the escape of the waters of a large lake raised far above the sea ; and, secondly, the pouring down of a marine current into lands depressed below the mean level of the ocean. Asan example of the first of these cases, we may take Lake Superior, which is more than 400 geographical miles in length and about 150 in breadth, having an average depth of from 500 to 900 feet. The surface of this vast body of fresh water is no less than 600 feet above the level of the ocean ; the lowest part of the barrier which separates the lake on its south-west side from those streams which flow into the head waters of the Mississippi being about 600 feet high. If, therefore, a series of subsidences should lower any part of this barrier, even a few yards at a time, or if earthquakes should rend it open, the breaches thus made might allow the sudden escape of vast floods of water into a hydrographical basin of enormous extent. Ifthe event happened in the dry season, when the ordinary channels of the Mississippi and its tribu- taries are in a great degree empty, the inundation might not be considerable ; but if in the flood-season, a region capable of supporting a population of many millions might be suddenly submerged. But even this event would be insuf- ficient to cause a violent rush of water, and to produce those effects usually called diluvial; for the difference of level of 600 feet between Lake Superior and the Gulf of Mexico, when distributed over a distance of 1,800 miles, would give an average fall of only four inches per mile. The second case before adverted to is where there are large tracts of dry land beneath the mean level of the ocean. It seems, after much controversy, to be at length a settled point, that the Caspian is really 83 feet 6 inches lower than the 112 SUPPOSED UNIVERSALITY [Cu. Vz. Black Sea. As the Caspian covers an area about equal to that of Spain, and as its shores are in general low and flat, there must be many thousand square miles of country i than 83 feet above the level of that inland sea, and congo. quently depressed below the Black Sea and editerranean, This area includes the site of the populous city of Astrakhan and other towns. Into this region the ocean would pour its waters, if the land now intervening between the Black Sea (or rather the Sea of Azof) and the Caspian should subside. Yet, even if this event should occur, it is most probable that the submergence of the whole region would not be accom- plished simultaneously, but by a series of minor floods, the sinking of the barrier being gradual.* The shores of the Dead Sea have lately been ascertained by a party of our Royal Engineers to be about 1,300 English feet below the level of the Mediterranean, or about four feet less than 1,300 on an average.t In this case, towns built on hills nearly 1,300 feet high might be submerged by such a change of level in the barrier as would open a communication between the Mediterranean and the valley of the Jordan. Supposed universality of ancient deposits.—The next fallacy which has helped to perpetuate the doctrine that the opera- tions of water were on a different and grander scale in ancient times, is founded on the indefinite areas over which homo- geneous deposits were supposed to extend. No modern sedi- it was said, equally identical in mineral character and fossil contents, can be traced continuously from one quarter of the globe to another. But the first propagators of these opinions were very slightly acquainted with the mentary strata, t has been suspected ever since oh mil of the th it being known that in Astrakhan the mercury in the barometer generally stands above thirty inches. In 1836, the Russian government Bae the Academy of St. Petersburg to send an a to determine ee relative level of the Caspian and Black Seas i} rl a survey. It was by found that the Caspian was 101 Rus- sian, or 108 English, feet lower than the Black Sea. (For authorities, see Journ. Roy. Geograph. Soe. vol. viii. p. 135.) Sir R. Murchison, however, concludes rities, that the eases 8 of the pian is only 83 feet 6 inche f Sir Henry James, who Sand this nt. 12th of March, 1865, the difference of level was 1,292 feet. The maximum panowi eerie: in Pe dry on the pete hee cae 1,289 b) fe et. Cu. VJ OF ANCIENT DEPOSITS. 113 inconstancy in mineral composition of the ancient formations, and equally so of the wide spaces over which the same kind of sediment is now actually distributed by rivers and currents im the course of centuries. The persistency of character in the older series was exaggerated, its extreme variability in the newer was assumed without proof. In the chapter which treats of river-deltas and the dispersion of sediment by currents, and in the description of reefs of coral now growing over areas many hundred miles in length, I shall have oppor- tunities of convincing the reader of the danger of hasty generalisations on this head. I may also mention in this place, that the vast distance to which the white chalk can be traced east and west over Hurope, as well as north and south, from Denmark to the Crimea, seemed to some geologists a phenomenon, to which the working of causes now in action could present no parallel. But the soundings made in the Atlantic for the submarine telegraph have taught us that white mud, formed of similar organic bodies and of like character, is in progress over spaces still more vast.* But in regard to the imagined universality of particular rocks of ancient date, it was almost unavoidable that this notion, when once embraced, should be perpetuated; for the same kinds of rock have occasionally been reproduced at successive epochs : and when once the agreement or disagree- ment in mineral character alone was relied on as the test of age, it followed that similar rocks, if found even at the antipodes, were referred to the same era, until could be shown. Now it is usually impossible to combat such an assumption on geological grounds, so long as we are imperfectly acquaint- ed with the order of superposition and the organic remains of these same formations. Thus, for example, the red marl and red sandstone, containing salt and gypsum (the Triassic group of the Table, p. 139), being interposed in England be- tween the Lias and the Coal, all othe stones, associa the contrary rred marls and sand- ted some of them with salt, and others with gypsum, and occurring not only in different parts of Europe, but in North America, Peru, India, the salt deserts of Asia, * Elements of Geol., 6th edit. p. 318, WA) Beja ie I 114 SUPPOSED UNIVERSALITY (Cu. VI those of Africa—in a word, in every quarter of the globe, were referred to one and the same period. The burden of proof was not supposed to rest with those who insisted on the identity in age of all these groups—their identity in mineral composition was thought sufficient. It was in vain to urge as an objection the improbability of the hypothesis which implies that all the moving waters on the globe were once simultaneously charged with sediment of a red colour. But the rashness of pretending to identify, in age, all the red sandstones and marls in question, has at length been sufficiently exposed, by the discovery that, even in Europe, they belong decidedly to many different epochs. The inves- tigations of De Verneuil in Spain have shown that the red sandstone and red marl, containing the rock-salt of Cardona in Catalonia, belong to the Middle Eocene or Nummulitic period. Itis also known that certain red marls and varie- gated sandstones in Auvergne which are undistinguishable in mineral composition from the New Red Sandstone of English eeologists, are nevertheless of the same older tertiary period: and, lastly, the gypseous red marl of Aix, in Provence, formerly supposed to be a marine secondary group, is now acknowledged to be a tertiary freshwater formation. In Nova Scotia one great deposit of red marl, sandstone, and gypsum, precisely resembling in mineral character the ‘ New Red’ of England, occurs as a member of the Carboniferous group, and in the United States near the Falls of Niagara, a similar formation constitutes a subdivision of the Upper Silurian series.* Nor was the nomenclature commonly adopted in geology without its influence in perpetuating the erroneous doctrine of universal formations. Such names, for example, as Chalk, Green Sand, Oolite, Red Marl, Coal, and others, were given to some of the principal fossiliferous groups in consequence of mineral peculiarities which happened to characterise them in the countries where they were first studied. When geolo- gists had at length shown, by means of fossils and the order of superposition, that other strata, entirely dissimilar in colour, texture, and composition, were of contemporaneous * See Lyell’s Travels in N. America, ch. 2, and 28. ; Cu. VI.] OF ANCIENT DEPOSITS. 115 date, it was thought convenient still to retain the old names. That these were often inappropriate was admitted ; but the student was taught to understand them in no other than a chronological sense; so that the Chalk might be a grey quartz- ose sandstone devoid of calcareous matter, as near Dresden, or a hard, compact, and sometimes flaggy limestone, as in parts of the Alps, or a brown sandstone or green marl, as in New Jersey, U.S. In like manner, the Green Sand, it was said, is often represented by limestone and other mineral masses entirely devoid of green grains. So the Oolitic tex- ture was declared to be rather an exception than otherwise to the general rule in rocks of the Oolitic period, and to be found in strata both of older and newer date; and it often became necessary to affirm that no particle of carbonaceous matter could be detected in districts where the true Coal series abounded. In spite of every precaution the habitual use of this language could scarcely fail to instil into the thind of the pupil an idea that chalk, coal, salt, red marl, or the Oolitic structure were far more widely characteristic of the rocks of a given age than was really the case. There is still another cause of deception, disposing us to ascribe a more limited range to the newer sedimentary forma- tions as compared to the older, namely, the very general concealment of the newer strata beneath the waters of lakes and seas, and the wide exposure above waters of the more ancient. The Chalk, for example, now seen stretching for thousands of miles over different parts of Europe, has become visible to us by the effect, not of one, but of many distinct series of subterranean movements. Time has been required, and a succession of geological periods, to raise it above the waves in so many regions; and if calcareous rocks of the middle and upper tertiary periods have been formed, as homogeneous in mineral composition throughout equally ex- tensive regions, it may require convulsions as numerous as all those which have occurred since the origin of the Chalk to bring them up within the sphere of human observation. Hence the rocks of more modern periods may appear partial, as compared to those of remoter eras, not because of any origina! inferiority in their extent, but because there has not 12 116 UNIFORMITY OF AQUEOUS CAUSES. [Cu. VI been sufficient time since their origin for the development of a great series of elevatory movements. ' In regard, however, to one of the most important character- istics of sedimentary rocks, their organic remains, many naturalists of high authority have maintained that the same species of fossils are more widely distributed through forma- ions of high antiquity than in those of more modern date, and that distinct zoological and botanical provinces, ag they are called, which form so striking a feature in the living creation, were not established at remote eras. Thus the plants of the Coal, the shells, and trilobites of the Silurian rocks, and the ammonites of the Oolite, have been supposed to have a wider geographical range than any living species of plants, crustaceans, or mollusks. This opinion seems in certain cases to be well founded, especially in relation to the plants of the Carboniferous epoch, owing partly to greater uniformity of climate, and partly, as Professor Heer has suggested, to the fact that almost all the plants—including even large trees— of that period, were cryptogamous: so that their minute spores might be carried by the wind for indefinite distances, as are now the spores of ferns, mosses, and lichens. Buta recent comparison of the fossils of North American rocks with those of corresponding ages in the European series, has proved that the terrestrial vegetation of the Carboniferous epoch is an exception to the general rule, and that the fauna and flora of the earth at successive periods, from the oldest Silurian to the newest Tertiary, was as diversified as now. The shells, corals, and other classes of organic remains demonstrate the fact that the earth might then have been divided into separate zoological provinces, in a manner analogous to that observed in the geographical distribution of species now living. ° | | 117 CHAPTER VII. ON THE SUPPOSED FORMER INTENSITY OF THE IGNEOUS FORCES. VOLCANIC ACTION AT SUCCESSIVE GEOLOGICAL PERIODS—PLUTONIC ROCKS OF DIFFERENT AGES—GRADUAL DEVELOPMENT OF SUBTERRANEAN MOVEMENTS— FAULTS—DOCTRINE OF THE SUDDEN UPHEAVAL OF PARALLEL MOUNTAIN- CHAINS—OBJECTIONS TO THE PROOF OF THE SUDDENNESS OF THE UPHEAVAL AND THE CONTEMPORANEOUSNESS OF PARALLEL CHAINS—TRAINS OF ACTIVE VOLCANOS NOT P. —AS LARGE TRACTS OF LAND ARE RISING OR SINK- ING SLOWLY, SO NAR ZONE F LAND MAY BE PUSHED UP GRADUALLY TO G EIGHTS—-BENDING OF STRATA BY LATERAL PRESSURE—ADEQUACY OF THE VOLCANIC POWER TO EFFECT THIS WITHOUT PAROXYSMAL CONVUL- IONS. WHEN reasoning on the intensity of volcanic action at former periods, as well as on the power of moving water, geologists have been ever prone to represent Nature as having been prodigal of violence and parsimonious of time. Now, although it is less easy to determine the relative ages of the volcanic than of the fossiliferous formations, it is undeniable that igneous rocks have been produced at all geological periods, or as often as we find distinct deposits marked by peculiar animal and vegetable remains. It can be shown that rocks commonly called trappean have been injected into fissures, and ejected at the surface, both before and during the deposition of the Lau- 7 a rentian, Cambrian, Silurian, and Ci 8 series (seeTable, page 139), and at the time when the Permian or Magnesian Limestone, and when the Upper New Red Sandstone were formed, or when the Lias, Oolite, Green Sand, Chalk, and the several tertiary groups newer than the chalk, originated in succession. Nor is this all; distinct volcanic products may be referred to the subordinate divisions of each period, such as the Carboniferous, as in the county of Fife, in Scotland, where certain masses of contemporaneous trap are associated 118 SUPPOSED FORMER INTENSITY (Cu, Vit with the Lower, others with the Upper Coal-measures. And if one of these masses is more minutely examined, we find it to consist of the products of a great many successive outbursts, by which scoriz and lava were again and again emitted, and afterwards consolidated, then fissured, and finally traversed by melted matter constituting what are called dykes.* As we enlarge, therefore, our knowledge of the ancient rocks formed by subterranean heat, we find ourselves compelled to regard them as the aggregate effects of innumerable erup- tions, each of which may have been comparable in violence to those now experienced in volcanic regions. It may indeed be said that we have as yet no data for estimating the relative volume of matter simultaneously in a state of fusion at two given periods, as if we were to compare the columnar basalt of Staffa and its environs with the lava poured out in Iceland in 1783; but for this very reason it would be rash and unphilosophical to assume an excess of ancient as contrasted with modern outpourings of melted matter at particular periods of time.t It would be still more presumptuous to take for granted that the more deep-seated effects of subterranean heat surpassed at remote eras the corresponding effects of internal heat in our own times. Certain porphyries and granites, and all the rocks commonly called plutonic, are now generally supposed to have resulted from the slow cooling of materials fused and solidified under ereat pressure ; and we cannot doubt that beneath existing voleanos there are large spaces filled with melted stone, which must for centuries remain in an incandescent state, and then cool and become hard and crystalline when the subterranean heat shall be exhausted. That lakes of lavaare continuous for hundreds of miles beneath the Chilian Andes, seems established by observations made in the year 1835.] Now, wherever the fluid contents of such reservoirs are poured out successively from craters in the open air, oF at the bottom of the sea, the matter so ejected may afford evidence by its arrangement of having originated at different * See Elements of Geology, 6th ed. ch. 27. chap. 30 to 32, inclusive. t See below, Chilian earthquake, Y See below, Icelandic eruptions, 28. ch. Cu. VII.) OF IGNEOUS FORCES. 119 periods ; but if the subterranean residue after the withdrawal of the heat be converted into crystalline or plutonic rock, the entire mass may seem to have been formed at once, however countless the ages required for its fusion and subsequent re- frigeration. As the idea that all the granite in the earth’s crust was produced simultaneously, and in a primitive state of the planet, has now been universaily abandoned; so the suggestion above adverted to, may put us on our ouard against too readily adopting another opinion, namely, that each large mass of granite was generated in a brief period of time. Modern writers indeed, of authority, seem more and more agreed that in the case of granitic rocks, the passage from a liquid or pasty to a solid and crystalline state must have been an extremely gradual process. The doctrine so much insisted upon formerly, that crystal- line rocks, such as granite, gneiss, mica-schist, quartzite, and others were produced in the greatest abundance in the earlier ages of the planet, and that their formation has ceased altogether in our own times, will be controverted in the next chapter. Gradual development of subterranean movements.—The ex- treme violence of the subterranean forces in remote ages has been often inferred from the facts that the older rocks are more fractured and dislocated than the newer. But what other result could we have anticipated if the quantity of movement had been always equal in equal periods of time ? Time must, in that case, multiply the derangement of strata in the ratio of their antiquity. Indeed the numerous excep- tions to the above rule which we find in nature, present at first sight the only objection to the hypothesis of uniformity. For the more ancient formations remain in many places horizontal, while in others much newer strata are curved and vertical. This apparent anomaly, however, will be seen in the next chapter to depend on the irregular manner in which the volcanic and subterranean agency affect different parts of the earth in succession, being often renewed again and again in certain areas, while others remain during the whole time at rest. 120 SUPPOSED FORMER INTENSITY [Cu. viy That the more impressive effects of subterranean power, such as the upheaval of mountain-chains, may have been due to multiplied convulsions of moderate intensity rather than to a few paroxysmal explosions, will appear the less impro. bable when the gradual and intermittent development of volcanic eruptions in times past is once established, It ig now very generally conceded that these eruptions have their source in the same causes as those which give rise to the permanent elevation and sinking of land; the admission, therefore, that one of the two volcanic or subterranean pro- cesses has gone on gradually draws with it the conclusion that the effects of the other have been elaborated by succes- sive and gradual efforts. Faults.—The same reasoning is applicable to great faults, or those striking instances of the upthrow or downthrow of large masses of rock, which have been thought by some to imply tremendous catastrophes wholly foreign to the ordinary course of nature. Thus we have in England faults in which he vertical displacement of the rocks amounts sometimes to several hundred, and in other cases to 3,000 feet, while the fissures extend horizontally for distances varying from a few hundred yards to thirty miles. Their original width, for they have been since filled up with rubbish, varied from a few inches to fifty feet. But when we enquire into the proofs of the mass having risen or fallen suddenly on the one side of these great rents, several hundreds or thousands of feet above or below the rock with which it was once continuous on the other side, we find the evidence defective. There are grooves, it is said, and scratches on the rubbed and polished walls, which have often one common direction, favouring the theory that the move- ment was accomplished by a single stroke, and not by a series of interrupted movements. But, in fact, the striz are not always parallel in such cases, but often irregular, and sometimes the stones and earth which are in the middle of the fault, or fissure, have been polished and striated by friction in different directions, showing that there have been slidings subsequent to the first introduction of the fragment- ary matter. Nor should we forget that the last movement must always tend to obliterate the signs of previous tritura- Cu, VII.] OF IGNEOUS FORCES. LOT tion, so that neither its instantaneousness nor the uniformity of its direction can be inferred from the parallelism of the striz that have been last produced. When rocks have been once fractured, and freedom of mo- tion communicated to detached portions of them, these will naturally continue to yield in the same direction, if the pro- cess of upheaval or of undermining be repeated again and again. The incumbent mass will always give way along the lines of least resistance, and therefore usually in the places where it was formerly rent asunder. Probably, the effects of reiterated movement, whether upward or downward, in a fault, may be undistinguishable from those of a single and instantaneous rise or subsidence ; and the same may be said of the rising or falling of continental masses, such as Sweden or Greenland, which we know to take place slowly and in- sensibly. Doctrine of the sudden upheaval of parallel mountain- chains.—The doctrine of the suddenness of many former revolutions in the physical geography of the globe has been thought by some to derive additional confirmation from a theory respecting the origin of mountain-chains, advanced in 1 y a distinguished geologist, M. Elie de Beaumont. In several essays on this subject, the last published in 1852, he has attempted to establish two points ; first, that a variety of independent chains of mountains have been thrown up suddenly at particular periods; and, secondly, that the con- temporaneous chains thus thrown up, preserve a parallelism the one to the other. These opinions, and others by which they are accompanied, are so adverse to the method of interpreting the history of geological changes which I have recommended in this work, that Iam desirous of explaining the grounds of my dissent, a course which I feel myself the more called upon to adopt, as the generalisations alluded to are those of a skilful writer, and an original observer of great talent and experience. I shall _ begin, therefore, by giving a brief summary of the principal propositions laid down in the works above referred to.* * Ann. des Sci. Nat., Septembre, No- Frangaise, No. 15. May, 1830. Bulletin vembre, et Décembre, 1829. Revue de la Société Géol. de France, p. 864. 199 SUPPOSED CONTEMPORANEOUS UPHEAVAL [Cu. Viz. 1st. M. de Beaumont supposes ‘ that in the history of the earth there have been long periods of comparative repose during which the deposition of sedimentary matter has souls on in regular continuity; and there have also been short periods of paroxysmal violence, during which that continuity was broken. ‘2dly. At each of these periods of violence or “ reyoly. tion,” in the state of the earth’s surface, a great number of mountain-chains have been formed suddenly. ‘3dly. The chains thrown up by a particular revolution have one uniform direction, being parallel to each other within a few degrees of the compass, even when situated in remote regions; whilst the chains thrown up at different periods have, for the most part, different directions. ‘4thly. Hach “revolution,” or “ great convulsion,” has fallen in with the date of another geological phenomenon; namely, “the passage from one independent sedimentary formation to another,” characterised by a considerable dif- ference in “ organic types.” ‘5thly. There has been a recurrence of these paroxysmal movements from the remotest geological periods; and they may still be reproduced, and the repose in which we live may hereafter be broken by the sudden upthrow of another system of parallel chains of mountains. ‘6thly. The origin of these chains depends not on partial volcanic action, or a reiteration of ordinary earthquakes, but on the secular refrigeration of the entire planet. For the whole globe, with the exception of a thin envelope, much thinner in proportion than the shell to an egg, is a fused mass, kept fluid by heat, but constantly cooling and con- tracting its dimensions. The external crust does not gradu- ally collapse and accommodate itself century after century to the shrunken nucleus, subsiding as often as there is a slight failure of support, but it is sustained throughout whole geological periods, so as to become partially separated from the nucleus, until at last it gives way suddenly, cracking and May, 1847. The latest edition of M. d’Hist. Nat. 1852, art. ‘ Systémes : de Beaumont’s theory will be found in Montagnes ;’ also the same Pp" the 12th vol. of the Dictionnaire Universel separately. nted ———————EE — —_—_—___- Cu. VIT.] OF PARALLEL MOUNTAIN-CHAINS. 123 falling in along determinate lines of fracture. During such a crisis the rocks are subjected to oreat lateral pressure, the unyielding ones are crushed, and the pliant strata bent, and are forced to pack themselves more closely into a smaller space, having no longer the same room to spread themselves out horizontally. At the same time, a large portion of the mass is squeezed upwards, because it is in the upward direc- tion only that the excess in size of the envelope, as compared to the contracted nucleus, can find relief. This excess pro- duces one or more of those folds or wrinkles in the earth’s crust which we call mountain-chains. ‘Lastly, some chains are comparatively modern; such as the Alps, which were partly upheaved after the middle ter- tiary period. The elevation of the Andes was much more recent, and was accompanied by the simultaneous outburst for the first time of 270 of the principal volcanos now active.* The agitation of the waters of the ocean caused by this convulsion probably occasioned that transient and general deluge which is noticed in the traditions of so many na- tions.’ TF Several of the topics enumerated in the above summary, such as the cause of interruptions in the sedimentary series, will be discussed in the 14th chapter, and I shall now confine myself to what I conceive to be the insufficiency of the proofs adduced in favour of the suddenness of the upthrow, and the contemporaneousness of the origin of the parallel chains referred to. Atthe same time I may remark, that the great body of facts collected together by M. de Beaumont will always form a most valuable addition to our knowledge, tending as they do to confirm the doctrine that different mountain-chains have been formed in succession, and, as Werner first pointed out, that there are certain determinate lines of direction or strike in the strata of various countries. The following may serve as an analysis of the evidence on which the theory above stated depends. ‘ We observe,’ says M. de Beaumont, ‘when we attentively examine nearly all mountain-chains, that the most recent rocks extend hori- zontally up to the foot of such chains, as we should expect * Systémes de Montagnes, p. 762. f Ibid. pp. 761 and 778. 124 THEORY OF SUDDEN RISE OF [Cu. VII. would be the case if they were deposited in seas or lakes, of ) which these mountains have partly formed the shores 5 whilst | | the other sedimentary beds, tilted up, and more or legs con- | torted, on the flanks of the mountains, rise in certain pointy even to their highest crests.’* There are, therefore, in and adjacent to each chain, two classes of sedimentary rocks, the | ancient or inclined beds, and the newer or horizontal. J; ig evident that the first appearance of the chain itself wag an event ‘intermediate between the period when the beds now upraised were deposited, and the period when the strata were produced horizontally at its feet.’ Rigi, fis Thus the chain A assumed its present position after the deposition of the strata b, which have undergone great move- ments, and before the deposition of the group ¢, in which the strata have not suffered derangement. ! If we then discover another chain B, in which we find not only the formation b, but the group ¢ also, disturbed and thrown on its edges, we may infer that the latter chain is of subsequent date to A; for B must have been elevated after the deposition of c, and before that of the eroup d; whereas A had originated before the strata c were formed. It is then argued, that in order to ascertain whether other mountain ranges are of contemporaneous date with A and B, or are referable to distinct periods, we have only to enquire * PI iil, Mag. and Annals, No. 58. New Series, p, 242. Cu. VII] PARALLEL MOUNTAIN-CHAINS. 195 whether the inclined and undisturbed sets of strata in each range correspond with or differ from those in the typical chains A and B. Now all this reasoning is perfectly correct, so long as the period of time required for the deposition of the strata b and c is not made identical in duration with the period of time during which the animals and plants found fossil in b and ¢ may have flourished ; for the latter, that is to say, the dura- tion of certain groups of species, may have greatly exceeded, and probably did greatly exceed, the former, or the time required for the accumulation of certain local deposits, such as b and ¢ (figs. 1 and 2). In order, moreover, to render the reasoning correct, due latitude must be given to the term contemporaneous; for this term must be understood to allude, not toa moment of time, but to the interval, whether brief or protracted, which elapsed between two events, namely, between the accumulation of the inclined and that of the horizontal strata. But, unfortunately, no attempt has been made in the treatises under review to avoid this manifest source of con- fusion, and hence the very terms of each proposition are equivocal; and the possible length of some of the intervals is so vast, that to affirm that all the chains raised in such intervals were contemporaneous is an abuse of language. In order to illustrate this argument, I shall select the Pyrenees as an example. Originally M. EH. de Beaumont spoke of this range of mountains as having been uplifted suddenly (4 wn seul jet), but he has since conceded that in this chain, in spite of the general unity and simplicity of its structure, six, if not seven, systems of dislocation of different dates can be recognised.* In reference, however, to the latest, and by far the most important of these convulsions, the chain is said to have attained its present elevation at a cer- tain epoch in the earth’s history, namely, between the depo- sition of the chalk, or rocks of about that age, and that of certain tertiary formations ‘as old as the plastic clay ;’ for the chalk is seen in vertical, curved, and distorted beds on the flanks of the chain, as the beds b, fig. 1, while the tertiary * Systemes de Montagnes, 1852, p. 429, 126 THEORY OF SUDDEN RISE OF ’ (Cu. VIq, formations rest upon them in horizontal strata at its bage as ¢, ibid. j The proof, then, of the extreme suddenness of the conyyl- sion is supposed to be the shortness of the time which intervened between the formation of the chalk and the origin of certain tertiary strata.* Even if the interval were re- ducible within these limits, it might comprise an indefinite lapse of time. In strictness of reasoning, however, ‘the author cannot exclude the Cretaceous or Tértiary periods from the possible duration of the interval during which the elevation may have taken place. For, in the first place, it cannot be assumed that the movement of upheaval took place after the close of the Cretaceous period ; we can merely say, that it occurred after the deposition of certain strata of that period; secondly, although it were true that the event happened before the formation of all the tertiary strata now at the base of the Pyrenees, it would by no means follow that it preceded the whole Tertiary epoch. The age of the strata, both of the inclined and horizontal series, may have been accurately determined by M. de Bean- mont, and still the upheaving of the Pyrenees may have been going on before the animals of the Chalk period, such as are found fossil in England, had ceased to exist, or when the Maestricht beds were in progress, or during the indefinite ages which may have elapsed between the extinction of the Maestricht animals and the introduction of the Hocene tribes, or during the Hocene epoch, or the rise may have been going on throughout one, or several, or all of these periods. It would be a purely gratuitous assumption to say that the inclined cretaceous strata (b, fig. 1) on the flanks of the Pyrenees, were the very last which were deposited during the Cretaceous period, or that, as soon as they were upheaved, all or nearly all the species of animals and plants now found fossil in them were suddenly exterminated ; yet, unless this can be affirmed, we cannot say that the Pyrenees were ?° upheaved during the Cretaceous period. Consequently, 4 other range of mountains, at the base of which cretaceous * Phil. Mag. and Annals, No. 68. New Series, p. 243. ce 1 Dy Cu. VIL] PARALLEL MOUNTAIN-CHAINS, 127 rocks may lie in horizontal stratification, may have been elevated, like the chain A, fig. 2, during some part of the same great period. There are mountains in Sicily two or three thousand feet high, the tops of which are composed of limestone, in which a large proportion of the fossil shells agree specifically with those now inhabiting the Mediterranean. Here, as in many other countries, the deposits now in progress in the sea, must inclose shells and other fossils specifically identical with those of the rocks constituting the contiguous land. So there are islands in the Pacific, where a mass of dead coral has emerged to a considerable altitude, while other portions of the mass remain beneath the sea, still increasing by the growth of living zoophytes and shells. The chalk of the Pyrenees, therefore, may at aremote period have been raised to an elevation of several thousand feet, while the species found fossil in the same chalk still continued to be repre- sented in the fauna of the neighbouring ocean. In a word, we cannot assume that the origin of a new range of moun- tains caused the Cretaceous period to cease, and served as the prelude to a new order of things in the animate creation. To illustrate the grave objections above advanced, against the theory considered in the present chapter, let us suppose, that in some country three styles of architecture had pre- vailed in succession, each for a period of one thousand years ; first the Greek, then the Roman, and then the Gothic; and that a tremendous earthquake was known to have occurred in the same district during one of the three periods—a con- vulsion of such violence as to have levelled to the ground all the buildings then standing. If an antiquary, desirous of discovering the date of the catastrophe, should first arrive at a city were several Greek temples were lying in ruins and half engulphed in the earth, while many Gothic edifices were standing uninjured, could he determine on these data the era of the shock ? Could he even exclude any one of the three periods, and decide that it must have happened during one of the other two? Certainly not. He could merely affirm that it happened at some period after the introduction of the Greek style, and before the Gothic had fallen into disuse. 128 THEORY OF SUDDEN RISE OF [Cu Viz. Should he pretend to define the date of the convulsion with ereater precision, and decide that the earthquake must have occurred after the Greek and before the Gothic period, that is to say, when the Roman style was in use, the fallacy in his reasoning would be too palpable to escape detection for a moment. Yet such is the nature of the erroneous induction of which Tam now treating. For as, in the example above proposed, the erection of a particular edifice is an event scarcely ever coextensive in time with the whole period of a certain style of architecture to which it conformed, so the de- position of chalk or any other set of strata may have been effected in a small part of that geological epoch to which the species of fossils characterising such strata may belong, It is almost superfluous to enter into any further analysis of the theory of parallelism, because the whole force of the argument depends on the accuracy of the data by which the contemporaneous or non-contemporaneous date of the ele- vation of two independent chains can be demonstrated. In every case, this evidence, as stated by M. de Beaumont, is equivocal, because he has not included in the possible interval of time between the deposition of the deranged and the horizontal formations, part of the periods to which each of those classes of formations are referable. Even if all the geological facts, therefore, adduced by the author were true and unquestionable, yet the conclusion that certain chains were or were not simultaneously upraised is by no means a legitimate consequence. In the third volume of my first edition of the Principles, which appeared in April 1833, I controverted the views of M. de Beaumont, then just published, in the same terms as I have now restated them. At that time I took for granted that the chronological date of the newest rocks entering into the disturbed series of the Pyrenees had been correctly ascertained. It now appears, however, that some of the most modern of those disturbed strata belong to the num- mulitic formation, which are now regarded by the majority of geologists as Hocene or lower tertiary. Perhaps a more striking illustration of the difficulties we Cu. VIL] PARALLEL MOUNTAIN-CHAINS. 129 encounter, when we attempt to apply the theory under con- sideration even to the best known Huropean countries, is afforded by what is called ‘The System of the Longmynds.’ This small chain, situated in Shropshire, is the third of the typical systems to which M. H. de Beaumont compares other mountain ranges corresponding in strike and structure. The date assigned to its upheaval is ‘after the unfossiliferous ereywacke, or Cambrian strata, and before the Silurian.’ But Sir R. I. Murchison had shown in 1858, in his ‘Silurian System,’ and the British Government surveyors, since that time, in their sections (about 1845), that the Lonemynds and other chains of similar composition in North Wales are post- Silurian. In all of them fossiliferous beds of the lower Silurian formation or Llandeilo flags are highly inclined, and often vertical. In one limited region the Caradoc sandstone, a member of the lower Silurian, rests unconformably on the denuded edges of the inferior (or Llandeilo) member of the same group; whilst in some cases both of these sets of strata are upturned. When, therefore, so grave an error is detected in regard to the age of a typical chain, we are entitled to enquire with surprise, by what means nine other parallel chains in France, Germany, and Sweden, assumed to be ‘ante-Silurian,’ have been made to agree precisely in date with the Longmynds? If they are correctly represented as having been all deposited before the deposition of the Silurian strata, they cannot be contemporaneous with the Longmynds, and they only prove how little reliance can be placed on parallelism as a test of simultaneousness of upheaval. But in truth it is impossible, for reasons already given, to demon- strate that each of those nine chains coincide in date with one another, any more than with the Longmynds. The reader will see in the sequel (Chap. XX XII.*) that Mr. Hopkins has inferred from astronomical calculations, that the solid crust of the earth cannot be less than 800 or 1000 miles thick, and may be more. Even if it be solid to the depth of a hundred miles, such a thickness would be incon- sistent with M. E. de Beaumont’s hypothesis, who requires a shell not more than thirty miles thick, or even less. Mr. * For page, see Index, vol. ii., ‘Hopkins,’ VOL. I, 130 THEORY OF SUDDEN RISE OF [Cx VIT Hopkins admits that the exterior of the planet, though golig as a whole, may contain within it vast lakes or seas of lava, If so, the gradual fusion of rocks, and the expansive power of heat exerted for ages, as well as the subsequent contraction of the same during slow refrigeration, may perhaps account for the origin of mountain-chains, for these, as Dolomiey has remarked, are ‘far less important, proportionally speak- ing, than the inequalities on the surface of an egg-shell, which to the eye appears smooth.’ A ‘centripetal force’ affecting the whole planet as it cools, seems a mightier cause than is required to produce wrinkles of such insignificant size. In pursuing his investigations, M. E. de Beaumont has of late greatly multiplied the number of successive periods of instantaneous upheaval, admitting at the same time that occasionally new lines of upthrow have taken the direction of older ones.* These admissions render his views much more in harmony with the principles advocated in this work, but they impair the practical utility of parallelism considered as a chronological test; for no rule is laid down for limiting the interval, whether in time or space, which may separate two parallel lines of upheaval of different dates. Among the various propositions above laid down (p. 122), it will be seen that the sudden rise of the Andes is spoken of as a modern event, but Mr. Darwin has brought together ample data in proof of the local persistency of volcanic action throughout a long succession of geological periods, begin- ning with times antecedent to the deposition of the oolitic and cretaceous formations of Chili, and continuing to the historical epoch. It appears that some of the parallel ridges which compose the Cordilleras, instead of being contem- poraneous, were successively and slowly upheaved at widely different epochs. The whole range, after twice subsiding *% ot are T * ; : ; s * Art. Systémes de Montagnes, p. intersect each other at certam angles, 8° we Phy ay- n 493 as to produce a regular geometri¢ if = : z : aon! + M. E. de Beaumont in his later rangement, which he calls “a pentagon’ = ors sae f(a , e : ee enquiries (Comptes rendus, Sept. 1850, network. This theory has been @ a \ - and Systémes de Montagnes) has come discussed and controverted by Mr. oa t : . a the conclusion, that the principal kins, in his Anniversary Ac mountain ranges, if prolonged, woulc President of the Geol. Soc., Feb, 18° ———— Cu. VII] PARALLEL MOUNTAIN-CHAINS. 131 some thousands of feet, was brought up again by a slow movement in mass, during the era of the Hocene tertiary formations, after which the whole sank down once more several hundred feet, to be again uplifted to its present level by a slow and often interrupted movement.* In a portion of this latter period the ‘ Pampean mud’ was formed, in which the Megatherium Mylodon and other extinct quad- rupeds are buried. This mud contains in it recent species of shells, some of them proper to brackish water, and is believed by Mr. Darwin to be an estuary or delta deposit. M. A. d’Orbigny, however, has advanced an hypothesis teferred to by M. EH. de Beaumont, that the agitation and dis- placement of the waters of the ocean, caused by the elevation of the Andes, gave rise to a deluge, of which this Pampean mud, which reaches sometimes the height of 12,000 feet, is the result and monument.t In studying many chains of mountains, we find that the strike or line of outcrop of continuous sets of strata, and the general direction of the chain, may be far from rectilinear. Curves forming angles of 20° or 30° may be found in the Same range as in the Alleghanies; just as trains of active volcanos and the zones throughout which modern earthquakes occur are often linear, without running in straight lines. Nor are all of these, though contemporaneous or belonging to our own epoch, by any means parallel, but some at right angles, the one to the other. Slow upheaval and subsidence.—Recent observations have disclosed to us the wonderful fact, that not only the west coast of South America, but also other large areas, some of them several thousand miles in circumference, such as Scandinavia, and certain archipelagos in the Pacific, are slowly and insensibly rising; while other regions, such as Greenland, and parts of the Pacific and Indian Oceans, in which atolls or circular coral islands abound, are as gra- dually sinking. That all the existing continents and sub- marine abysses may have originated in movements of this’ kind, continued throughout incalculable periods of time, is Sn athe e Pi tai, of South Ame- t Systémes de Montagnes, p. 748. K 2 132 UPHEAVAL AND SUBSIDENCE (Cu, VIz undeniable, for marine remains are found in rocks at almost all elevations above the sea, and the denudation which the dry land appears to have suffered, favours the idea that jt was raised from the deep by a succession of upward moye- ments, prolonged throughout indefinite periods. Rain and rivers, aided sometimes by slow and sometimes by sudden and violent movements of the earth’s crust, have undoubtedly excavated some of the principal valleys; but there are also wide spaces which have been denuded in such a manner ag can only be explained by reference to the action of waves and currents on land slowly emerging from the deep. But perhaps it may be said that there is no analogy be- tween the slow upheaval of broad plains or table-lands, and the manner in which we must presume all mountain-chains, with their inclined strata, to have originated. It seems, how- ever, that the Andes have been rising century after century, at the rate of several feet, while the Pampas on the east have been raised only a few inches in the same time. Crossing from the Atlantic to the Pacific, in a line passing through Mendoza, Mr. Darwin traversed a plain 800 miles broad, the eastern part of which has emerged from beneath the sea ata very modern period. The slope from the Atlantic is at first very gentle, then greater, until the traveller finds, on reach- ing Mendoza, that he has gained, almost insensibly, a height of 4,000 feet. The mountainous district then begins suddenly, and its breadth from Mendoza to the shores of the Pacific is 120 miles, the average height of the principal chain being from 15,000 to 16,000 feet, without including some promi- nent peaks, which ascend much higher. Now all we require, to explain the origin of the principal inequalities of level here described, is to imagine, first, a zone of more violent move- ment to the west of Mendoza, and, secondly, to the east of that place, an upheaving force, which died away gradually as it approached the Atlantic. In short, we are only called upon to conceive, that the region of the Andes was pushed up four feet in the same period in which the Pampas neat Mendoza rose one foot, and the plains near the shores ° the Atlantic one inch. In Europe the land at the North Cape is said to ascend about five feet in a century, while ns sali Cu. VIL] OF MOUNTAIN-CHAINS. 133 farther to the south the movements diminish in quantity first to a foot, and then, at Stockholm, to three inches in a cen- tury, while at certain points still farther south there is no movement. But in what manner, it is asked, can we account for the eveat lateral pressure which has been exerted not only in the Andes, Alps, and other chains, but also on the strata of many low and nearly level countries? Do not the folding and frac- ture of the beds, the anticlinal and synclinal ridges and troughs, as they are called, and the vertical, and even some- times the inverted position of the beds, imply an abruptness and intensity in the disturbing force wholly different in kind and energy to that which now rends the rocks during ordi- nary earthquakes? I shall treat more fully in the sequel (end of Chap. XXXIII.) of the probable subterranean sources, whether of upward or downward movement, and of great lateral pressure ; but it may be well briefly to state in this place that in our own times, as, for example, in Chili, in 1822, the volcanic force has overcome the resistance, and permanently uplifted a country of such vast extent that the weight and volume of the Andes must be insignificant in comparison, even if we indulge the most moderate conjectures as to the thickness of the earth’s crust above the volcanic foci. To assume that any set of strata with which we are ac- quainted are made up of such cohesive and unyielding mate- rials, as to be able to resist a power of such stupendous energy, if its direction, instead of being vertical, happened to be oblique or horizontal, would be extremely rash. But if they could yield to a sideway thrust, even in a slight degree, they would become squeezed and folded to any amount if subjected for a sufficient number of times to the repeated ac- tion of the same force. We can scarcely doubt that a mass of rock several miles thick was uplifted in Chili in 1822 and 1835, and that a much greater volume of solid matter is up- heaved wherever the rise of land is very gradual, as in Scan- dinavia, the development of heat being probably, in that region, at a greater distance from the surface. If continents, rocked, shaken and fissured, like the western region of South 134 UPHEAVAL AND SUBSIDENCE (Cm. Vit America, or very gently elevated, like Norway aud Sweden, do not acquire in a few days or hours an additional height of several thousand feet, this can arise from no lack of me- chanical force in the subterranean moving cause, but sim ly because the antagonist power, or the strength, toughness, anq density of the earth’s crust is insufficient to resist, so long, as to allow the voleanic energy an indefinite time to accumny- late. Instead of the explosive charge augmenting in quantity for countless ages, it finds relief continuously, or by a suc. cession of shocks of moderate violence, so as never to burst or blow up the covering of incumbent rock in one grand paroxysmal convulsion. Even in its most energetic efforts it displays an intermittent and mitigated intensity, being never permitted to lay a whole continent in ruins. Hence the nu- merous eruptions of lava from the same vent, or chain of vents, and the recurrence of similar earthquakes for thousands of years along certain areas or zones of country. Hence the numerous monuments of the successive ejection and injection of melted matter in ancient geological epochs, and the fis- sures formed in distinct ages, and often widened and filled at different eras. Among the causes of lateral pressure, the expansion by heat of large masses of solid stone intervening between others which have a different degree of expansibility, or which hap- pen not to have their temperature raised at the same time, may play an important part. It may also happen that hot vapours or thermal waters charged with various mineral matters in solution, may permeate rocks, and while they rise to new chemical combinations and a metamorphic structure, may augment their volume. We know also that at every period some countries have sunk down hundreds or thou- sands of feet below their original level, and we can hardly doubt that much of the bending of pliant strata, and the packing of the same into smaller spaces, has been occasioned by such subsidence. Whether the failure of support be pro- duced by the melting of porous rocks, which, when fluid, and subjected to great pressure, may occupy less room than before, or which, by passing from a pasty to a crystalline condition, may, as in the case of granite, according to the experiments J = fa ~ an a yy oa z FA f Cu. VII.] OF MOUNTAIN-CHAINS. 135 of Deville, suffer a contraction of 10 per cent., or whether the sinking be due to the subtraction of lava driven elsewhere to some volcanic orifice, and there forced outwards, or whether it be brought on by the shrinking of solid and stony masses during refrigeration, or by the condensation of gases, or any other imaginable cause, we have no reason to incline to the idea that the consequent geological changes are brought about so suddenly, as that large parts of continents are swal- lowed up at once in unfathomable subterranean abysses. If cavities be formed, they will be enlarged gradually, and as gradually filled. We read, indeed, accounts of engulphed cities and areas of limited extent which have sunk down many yards at once; but we have as yet no authentic records of the sudden disappearance of mountains, or the submergence or emergence of great islands. On the other hand, the creeps in coal mines* demonstrate that gravitation begins to act as goon as a moderate quantity of matter is removed even at a great depth. The roof sinks in, or the floor of the mine rises, and the bent strata often assume as regularly a curved and crumpled arrangement as that observed on a grander scale in mountain-chains. The absence, indeed, of chaotic disorder, and the regularity of the plications in geological formations of high antiquity, although not unfrequently adduced to prove the unity and instantaneousness of the disturbing force, might with far greater propriety be brought forward as an argument in favour of the successive application of some irresistible but moderated force, such as that which can elevate or depress a continent. _ In conclusion, I may observe that one of the soundest ob- jections to the theory of the sudden upthrow or downthrow of mountain-chains is this, that it provides us with too much force of one kind, namely, that of subterranean movement, while it deprives us of another kind of mechanical force, namely, that exerted by the waves and currents of the ocean, which the geologist requires for the denudation of land dur- ing its slow upheaval or depression. It may be safely affirmed that the quantity of igneous and aqueous action—of volcanic eruption and denudation—of subterranean movement and * See Lyell’s Elements of Geology, ch. v. p. 50. 136 UPHEAVAL AND SUBSIDENCE [Cx. VII, sedimentary deposition—not only of past ages, but of one geological epoch, or even the fraction of an epoch, hag ex. ceeded immeasurably all the fluctuations of the inorganic world which have been witnessed by man. But we have still to enquire whether the time to which each chapter or page or paragraph of the earth’s autobiography relates, was not equally immense when contrasted with a brief era of 3,000 or 5,000 years. The real point on which the whole controversy turns, is the relative amount of work done by mechanical force in given quantities of time, past and present. Before we can determine the relative intensity of the force employed, we must have some fixed standard by which to measure the time expended in its development at two distinct periods. Tt is not the magnitude of the effects, however gigantic their proportions, which can inform us in the slightest degree whether the operation was sudden or gradual, insensible or paroxysmal. It must be shown that a slow process could never in any series of ages give rise to the same results. The advocate of paroxysmal energy might assume an uni- form and fixed rate of variation in times past and present for the animate world, that is to say, for the dying-out and coming-in of species, and then endeavour to prove that the changes of the inanimate world have not gone on in a cor- responding ratio. But the adoption of such a standard of comparison would lead, I suspect, to a theory by no means favourable to the pristine intensity of natural causes. That the present state of the organic world is not stationary, can be fairly inferred from the fact, that some species are known to have become extinct in the course even of the last three centuries, and that the exterminating causes always in acti- vity, both on the land and in the waters, are very numerous ; also, because man himself is an extremely modern creation; and we may therefore reasonably suppose that some of the mammatia now contemporary with man, as well as a variety of species of inferior classes, may have been recently intro- duced into the earth, to supply the places of plants and ani- mals which have from time to time disappeared. But granting that’ some such secular variation in the zoological and botanical worlds is going on, and is by no means wholly in- Cu. VIL] OF MOUNTAIN-CHAINS. 137 appreciable to the naturalist, still it is certainly far less manifest than the revolution always in progress in the inor- ganic world. very year some voleanic eruptions take place, and a rude estimate might be made of the number of cubic feet of lava and scoriz poured or cast out of various craters. The amount of mud and sand deposited in deltas, and the advance of new land upon the sea, or the annual retreat of wasting sea-cliffs, are changes the minimum amount of which might be roughly estimated. The quantity of land raised above or depressed below the level of the sea might also be computed, and the change arising from such movements in a century might be conjectured. Suppose the average rise of the land in some parts of Scandinavia to be as much as five feet in a hundred years, the present sea-coast might be uplifted 700 feet in fourteen thousand years; but we should have no reason to anticipate, from any zoological data hitherto acquired, that the molluscous fauna of the northern seas would in that lapse of years undergo any sensible amount of variation. We discover sea-beaches in Norway 700 feet high, in which the shells are identical with those now living, although their geographical distribution has somewhat al- tered, the fossil species constituting an assemblage which at present characterises the sea several degrees farther north. The rise of land in Scandinavia, however insensible to the inhabitants, has evidently been rapid when compared to the rate of contemporaneous change in the testaceous fauna of the German Ocean. Were we to wait, therefore, till the mollusca shall have undergone as much alteration as they underwent between any two of the twelve larger groups from the Laurentian to the Pliocene enumerated in the table at the end of this chapter, or even in the time intervening be- tween the minor subdivisions of some of these groups, such as the eight ascribed to the Jurassic.or the six into which the Cretaceous are there divided, what stupendous revolutions in physical geography ought we not to expect, and how many mountain-chains might not be produced by the repe- tition of shocks of moderate violence, or by movements not even perceptible to man! r, if we turn from the mollusca to the vegetable kingdom, 138 UPHEAVAL AND SUBSIDENCE OF MOUNTAINS. [Cx yy and ask the botanist how many earthquakes and volcanic eruptions might be expected, and how much the relative level] of land and sea might be altered, or how far the principal deltas will ese upon the ocean, or the sea-cliffs recede from the present shores, before the species of European foregt- trees will die out, he would reply that such alterations in the inanimate world might be multiplied indefinitely before he should have reason to anticipate, by reference to any known data, that the existing species of trees in our forests would disappear and give place to others. In a word, the movement of the inorganic world is obvious and palpable, and might be likened to the minute-hand of a clock, the progress of which can be seen and heard, whereas the fiuctuations of the living creation are nearly invisible, and resemble the motion of the hour-hand of a timepiece. It is only by watching it atten- tively for some time, and comparing its relative position after an interval, that we can prove the reality of its motion.* the Author’s Anniversary Ad- vol. vi. p. 46, from which some of the oi “Quart Journ. Geol. Soc. 1850, above passages are extracted, X ) Cu. VII.] GENERAL TABLE OF FOSSILIFEROUS STRATA. 189 x M\ ApripGep GENERAL TABLE OF FOssILIFEROUS STRATA; SHOWING THEIR CHRONOLO- x GICAL SUCCESSION AND ORDER OF SUPERPOSITION.* %: om 1. RECENT. My, : POST-TERTIARY. ‘ 2, POST-PLIOCENE. ty 3, NEWER PLIOCENE. j ) F : PLIOCENE. ‘ 4. OLDER PLIOCENE. \ wen (aice] ” 5, UPPER MIOCENE. < 7 : MIOCENE. os ‘NX 6. LOWER MIOCENE. = “y 7. UPPER EOCENE. poe 8. MIDDLE EOCENE. EOCENE. 9. LOWER HOCENE. ity 10. MAESTRICHT BEDS. thet: 11, WHITE CHALK. | or CAINOZOIC. 12. UPPER GREENSAND. CRETACEOUS. 13. GAULT. NEOZOIC. 14. LOWER GREENSAND. “ 15, WEALDEN. ait 16. PURBECK BEDS. 17. PORTLAND STONE. ot 18. KIMMERIDGE CLAY. \ or MESOZOIC. 19. CORAL RAG. CONDARY - JURASSIC. nv 20. OXFORD CLAY. SI 21. GREAT or BATH OOLITE. | 22, INFERIOR OOLITE, | 23. LIAS. J | 24, UPPER TRIAS. | 25. MIDDLE TRIAS, TRIASSIC. i 26. LOWER TRIAS. 27. PERMIAN. PERMIAN. 2s: COAT. MER ASTTRES 29, CARBONIFEROUS CARBONIFEROUS. | LIMESTONE. 30. UPPER 31, MIDDLE DEVONIAN. DEVONIAN, 32. LOWER PRIMARY or PALMOZOIO, PALAOZOIC. 33. UPPER 34. MIDDLE SILURIAN, SILURIAN. 35, LOWER ~ 86. UPPER . 37. LOWER } CAMBRIAN, CAMBRIAN. 38, UPPER ! LAURENTIAN, EBAURENTIAN. . | | | 39, LOWER | - * For a more detailed and extended listsee ‘Elements of Geology,’ 6th edit. p. 102. 140 CHAPTER VIII. DIFFERENCE IN TEXTURE OF THE OLDER AND NEWER ROOKS, CONSOLIDATION OF FOSSILIFEROUS STRATA——-SOME DEPOSITS ORIGINALLY SOLID —TRANSITION AND SLATY TEXTURE—CRYSTALLINE CHARACTER OF PLUTONIC AND METAMORPHIC ROCKS—THEORY OF THEIR ORIGIN—ESSENTIALLY SUB- TERRANEAN—NO PROOFS THAT THEY WERE PRODUCED MORE ABUNDANTLY AT REMOTE PERIODS. ANOTHER argument in‘favour of the dissimilarity of the causes operating at remote and recent eras has been derived by many geologists from the more compact, stony, and crystalline texture of the older as compared to the newer rocks. Consolidation of strata.—This subject may be considered, first, in reference to the fossiliferous strata; and, secondly, in reference to those crystalline and stratified rocks which contain 20 organic remains, such as gneiss and mica-schist. There can be no doubt that the former of these classes, or the fossiliferous, are generally more compact and stony i proportion as they are more ancient. It is also certain that a great part of them were originally in a soft and incoherent state, and that they have been since consolidated. Thus we find occasionally that shingle and sand have been ageluti- nated firmly together by a ferruginous or siliceous cement, oF that lime in solution has been introduced, so as to bind toge- ther materials previously incoherent. Organic remains have sometimes suffered a singular transformation, as, for example; where shells, corals, and wood are silicified, their calcareous or ligneous matter having been replaced by nearly pur silica. The constituents of some beds have probably set and become hard for the first time when they emerged from beneath the water. Cu. VIL] TEXTURE OF OLDER AND NEWER ROCKS. 141 But, on the other hand, we observe in certain formations Bow in progress, particularly in coral reefs, and in deposits from the waters of mineral springs, both calcareous and siliceous, that the texture of rocks may sometimes be stony from the first. This circumstance may account for exceptions to the general rule, not unfrequently met with, where solid strata are superimposed on others of a plastic and incoherent nature, as in the neighbourhood of Paris, where the tertiary formations, consisting often of compact limestone and siliceous grit, are more stony than the subjacent chalk. It will readily be understood, that the various solidifying causes, including those above enumerated, together with the pressure of incumbent rocks and the influence of subterra- nean heat, must all of them require time in order to exert their full power. If in the course of ages they modify the aspect and internal structure of stratified deposits, they will give rise to a general distinctness of character in the older as contrasted with the newer formations. Transition texture.—In the original classification of Werner, the highly crystalline rocks, such as eranite and gneiss, which contain no organic remains, were called primary, and the fossiliferous strata secondary, while to another class of an age intermediate between the primary and secondary he gave the name of transition. They were termed transition because they partook in some degree in their mineral composition of the nature of the most crystalline rocks, such as gneiss and mica-schist, while they resembled the fossiliferous series in containing occasionally organic remains, and exhibiting evident signs of a mechanical origin. It was at first imagined, that the rocks having this intermediate texture had been all deposited subsequently to the series called primary, and before all the more earthy and fossiliferous formations. But when the relative position and organic remains of these transition rocks were better understood, it was perceived that they did not all belong to one period. On the contrary, the same mineral characters were found in strata of very different ages, and some formations occurring in the Alps, which several of the ablest scholars of Werner had determined to be transition, were ultimately ascertained, by means of their 42 DIFFERENCE IN TEXTURE OF [Cu. Viny, fossil contents and position, to be members of the Cretaceous, and even of the nummulitic or Eocene period. These strata had, in fact, acquired the transition texture from the influence of causes which, since their deposition, had modified their internal arrangement. Texture and origin of Plutonic and metamorphic rocks. — Among the most singular of the changes superinduced op rocks, we have occasionally to include the slaty texture, the divisional planes of which sometimes intersect the true planes of stratification, and even pass directly through imbedded fossils. If, then, the crystalline, the slaty, and other modes of arrangement, once deemed characteristic of certain periods in the history of the earth, have in reality been assumed by fossiliferous rocks of different ages and at different times, we are prepared to enquire whether the same may not be true of the most highly crystalline state, such as that of gneiss, mica- schist, and statuary marble. That the peculiar character- istics of such rocks are really due to a variety of modifying causes is now very generally admitted, and the differences of opinion among geologists which still prevail, relate chiefly to the manner in which the transformation has been brought about. According to the original Neptunian theory, all the crystalline formations were precipitated from a universal menstruum or chaotic fluid antecedently to the creation of animals and plants, the unstratified granite having been first thrown down so as to serve as a floor or foundation on which gneiss and other stratified rocks might repose. Afterwards, when the igneous origin of granite was no longer disputed, many conceived that a thermal ocean enveloped the globe, at a time when the first-formed crust of granite was cooling, but when it still retained much of its heat. The hot waters of this ocean held in solution the ingredients of gneiss, mica- schist, hornblende-schist, clay-slate, and marble, rocks which were precipitated, one after the other, in a crystalline form. No fossils could be inclosed in them, the high tempe- rature of the fluid and the quantity of mineral matter which it held in solution, renderi ing it unfit for the support ot organic beings. Tt would be inconsistent with the plan of this work to ng We Cu. VIII.) THE OLDER AND NEWER ROCKS. 1438 enter here into a detailed account of what I have elsewhere termed the metamorphic theory ;* but I may state that it is now demonstrable in some countries that fossiliferous forma- tions, some of them older than the Cambrian strata of our table, p. 1389, others of the age of the Silurian strata, as near Christiana in Norway, others belonging to the Oolitic period, as around Carrara in Italy, and some even of tertiary date, as in the Swiss Alps, have been converted into gneiss, mica- schist, or statuary marble. The transmutation has been effected by the influence of subterranean heat acting under ereat pressure, and aided by thermal water or steam and other gases permeating the porous rocks, and giving rise to various chemical decompositions and new combinations, the whole of which action has been termed ‘ plutonic,’ as express- ing in one word all the modifying causes brought into play at great depths, and under conditions never exemplified at the surface.+ To this Plutonic action the fusion of granite itself in the bowels of the earth, as well as the super-induce- ment of the metamorphic texture into sedimentary strata, may be attributed ; and in accordance with these views the age of each metamorphic formation may be said to be twofold, for we have first to consider the period when it originated, as an aqueous deposit, in the form of mud, sand, marl, or lime- stone; secondly, the date at which it acquired a crystalline texture. The same strata, therefore, may, according to this view, be very ancient in reference to the time of their deposi- tion, and comparatively modern in regard to the period of their assuming the metamorphic character. No proofs that these crystalline rocks were produced more abundantly at remote periods.—Several modern writers, without denying the truth of the Plutonic or metamorphic theory, still contend that the crystalline and non-fossiliferous forma- tions, whether stratified or unstratified, such as gneiss and granite, are essentially ancient as a class of rocks. They were generated, say they, most abundantly in a primeval state of the globe, since which time the quantity produced has been always on the decrease, until it became very incon- * See Lyell’s Elements or Manual of t See ‘Elements :’ Remarks on hy- Geology, ch. xxxy. drothermal action, p. 731. 144 DIFFERENCE IN TEXTURE OF (Cu. Vint, siderable in the Oolitic and Cretaceous periods, and quite evanescent before the commencement of the tertiary epoch, Now the justness of these views depends almost entirely on the question whether granite, gneiss, and other rockg of the same order ever originated at the surface, or whether, according to the opinions above adopted, they are essentially subterranean in their origin, and therefore entitled to the appellation of hypogene. If they were formed superficially in their present state, and as copiously in the modern as in the more ancient periods, we ought to see a greater abundance of tertiary and secondary than of primary granite and gneiss; but if we adopt the hypogene theory before explained, their rapid diminution in volume among the visible rocks in the earth’s crust in proportion as we investigate the formations of newer date, is quite intelligible. If a melted mass of matter be now cooling very slowly at the depth of several miles beneath the crater of an active volcano, it must remain invisible until great revolutions in the earth’s crust have been brought about. So also if stratified rocks are now by hydrothermal action, or under the influence of intensely heated steam and other gases undergoing semi-fusion and reconstruction far underground, it will probably require the lapse of many periods before they will be forced up to the surface and exposed to view, even at a single point. To effect this purpose there may be need of as great a develop- ment of subterranean movement as that which in the Alps, Andes, and Himalaya has raised strata containing marine fossil shells, and ammonites to the height of 8,000, 14,000, and 16,000 feet. By parity of reasoning we can hardly expect that any tertiary rocks of the hypogene class will have been brought within the reach of human observation, save at a few isolated points, seeing that the emergence of such rocks must always be so long posterior to the date of their origi, and still less can formations of this class become oenerally visible until so much time has elapsed as to confer on them a high relative antiquity. Extensive denudation must also combine with upheaval before they can be displayed at the surface throughout wide areas. All geologists who reflect on subterranean movements noW ae —< % . a, > ‘ ‘ Al fh: Ni Ay &) Cx. VIII.] THE OLDER AND NEWER ROCKS. 145 going on, and the eruptions of active volcanos, are convinced that great changes are now continually in progress in the interior of the earth’s crust far out of sight. They must be conscious, therefore, that the inaccessibility of the regions in which these alterations are taking place, compels them to remain in ignorance of a great part of the working of existing causes, so that they can only form vague conjectures in regard to the nature of the products which volcanic heat, aided by steam and other gases, may elaborate under great pressure. But when they find in mountain-chains of high antiquity, that what was once the interior of the earth’s crust has since been forced outwards and exposed to view, they will naturally expect in the examination of those mountainous regions, to have an opportunity of gratifying their curiosity by obtaining a sight not only of the superficial strata of remote eras, but also of the contemporaneous nether-formed rocks. Having recognised, therefore, in such mountain-chains some ancient rocks of aqueous and volcanic origin, corresponding in cha- racter to superficial formations of modern date, they will regard any other class of ancient rocks, such as granite and eneiss, as the residual phenomena of which they are in search. These latter rocks will not answer the expectations previously formed of their probable nature and texture, unless they wear a foreign and mysterious aspect, and bear the marks of having been altered by subterranean heat and gases under great pressure; in a word, unless they differ wholly from the fossiliferous strata deposited at the surface, or from the lava and scorie thrown out by volcanos in the open air. It is the total distinctness, therefore, of crystalline formations, such as granite, hornblende-schist, and the rest, from every substance of which the origin is familiar to us, that consti- tutes their claim to be regarded as the effects of causes now in action in the subterranean regions. They belong not to an order of things which has passed away; they are not the monuments of the primeval period, bearing inscribed upon them in obsolete characters the words and phrases of a dead language; but they teach us that part of the living language of nature, which we cannot learn by our daily intercourse with what passes on the habitable surface. VOL. I L 146 CHAPTER IX. THEORY OF THE PROGRESSIVE DEVELOPMENT OF ORGANIC LIFE AT SUCCESSIVE GEOLOGICAL PERIODS. THEORY OF THE PROGRESSIVE DEVELOPMENT OF ORGANIC LIFE—EVIDENCE IN ITS SUPPORT DERIVED FROM FOSSIL PLANTS——-FOSSIL ANIMALS—MOLLUSCA — WHETHER THEY HAVE ADVANCED IN GRADE SINCE THE EARLIEST ROCKS BIRDS — MAMMALIA — STONESFIELD MARSUPIALS—ABSENCE OF CETACEA IN MAMMALIA OF ADVANCING GRADE IN CHRONOLOGICAL ORDER — MODERN THE SYSTEM. In the last chapter we considered whether the doctrine ot the greater intensity of the igneous and aqueous causes in remote ages has any foundation in fact, and whether the peculiar crystalline texture of many of the older rocks favours the opinion that the former changes in the earth’s crust, of which geology treats, were governed by other than ordinary causes. We may now discuss the arguments derived from the organic creation in support of the notion that there is a want of analogy and continuity between the past and present course of events in the natural world. The objections on this head were formally stated in 1830, by the late Sir Humphrey Davy. ‘It is impossible,’ he affirms, ‘ to defend the proposition, that the present order of things is the ancient and constant order of nature, only modified by exist- ing laws: in those strata which are deepest, and which must, consequently, be supposed to be the earliest deposited, forms even of vegetable life are rare; shells and vegetable remains are found in the next order; the bones of fishes and ovipa- rous reptiles exist in the following class; the yemains of a — -_queeree . Ga EX] DEVELOPMENT OF ORGANIC LIFE. 147 birds, with those of the same genera mentioned before, in the next order ; those of quadrupeds of extinct species in a still more recent class; and it is only in the loose and slightly consolidated strata of gravel and sand, and which are usually called diluvial formations, that the remains of animals such as now people the globe are found, with others belonging to extinct species. But, in none of these forma- tions, whether called secondary, tertiary, or diluvial, have the remains of man, or any of his works, been discovered ; and whoever dwells upon this subject must be convinced, that the present order of things, and the comparatively recent existence of man as the master of the globe, is as cer- tain as the destruction of a former and a different order, and the extinction of a number of living forms which have no types in being. In the oldest secondary strata there are no remains of such animals as now belong to the surface; and in the rocks, which may be regarded as more recently deposited, these remains occur but rarely, and with abun- dance of extinct species ;—there seems, as it were, a eradual approach to the present system of things, and a succession of destructions and creations preparatory to the existence of man.’* In the above passages the author has done little more than reiterate the theory of progression which Lamarck had pro- posed about thirty years before in his Philosophy of Zoology. Another interval of more than thirty years has again elapsed since Davy wrote, one marked by ever-increasing activity in paleontological research, yet the new facts brought to light have scarcely made it necessary to modify any one of the leading propositions above enumerated. Fossil remains of man and rude works of art have, it is true, been detected in the formations termed by Sir H. Davy diluvial, in which the bones of the mammoth and other extinct quadrupeds so frequently occur. But, although these discoveries have enabled us to trace back the memorials of our race one short step farther into the past, they have not shaken our belief in the extremely modern date of the human era, as compared to that of a vast series of antecedent epochs, each of them * Sir H. Davy, Consolations in Travel: Dialogue III. ‘ The Unknown,’ L2 148 DEVELOPMENT OF ORGANIC LIFE [Cu. IX. characterised by distinct species of animals and plants,* The dates of the successive appearance of certain classes, orders, and genera, those of higher organisation always characterising rocks newer in the series, have often been mis- stated,t and the detection of chronological errors has engen- dered doubts as to the soundness of the theory of progression, In these doubts I myself indulged freely in former editions of this work. But after numerous corrections have been made as to the date of the earliest signs of life on the globe, and the periods when more highly organised. beings, whether animal or vegetable, first entered on the stage, the original theory may be defended in a form but slightly modified. Fossil plants.—To speak first of the vegetable creation— recent investigations have made it more and more clear that the oldest known flora was characterised by a great predomi- nance of cryptogamous plants. In the Devonian flora of North America the lycopodiaceous genera, such as the Lepi- dodendra, were the most numerous, while the associated plants, such as Sigillariz, ferns, and Conifers, although they are specifically distinct, agree generically with those of the carboniferous strata which come next in succession. It had been suggested that the absence, in the true coal, of the higher grade of flowering plants, (the dicotyledonous angio- sperms of Brongniart,) which now constitute four-fifths of the vegetation of the globe, might be explained by supposing that the fossil species represent those only which grew in a par- ticular class of stations, such as low swamps bordering the sea; and that more highly organised genera and species would have become known to us, had we been acquainted with the flora of the higher and mountainous regions. But, although it is now universally admitted that the plants which form the bulk of the coal grew on the spots where we now find that fuel, yet there are many vegetable remains in the associated sand- stones, which must have been drifted from a distance oF * In my work on the Antiquity of Man, 1863, I have given, p. 295, a concise statement of the doctrine of progression as laid down by Prof. Sedgwick, the late Hugh Miller, M. Agassiz, Prof. Owen, and Profs. Bronn and Adolphe Brongniart, as applied both to the animal and vegetable worlds, which I need not repeat in the present chapter. + See my Elements of Geology; P- 853. Cu. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS 149 washed down by great rivers from higher grounds to the sea- coast. Nor can we point to a marsh in the delta of any existing river, where ferns and other Cryptogams together with Conifer flourish, to the exclusion of all the more highly organised plants. Certain fruits and leaves of the coal-measures, formerly supposed to be those of palms, are now very generally referred to plants of less perfect structure, being variously classed by potanists as cycads, conifers, or lycopodiacewe. ‘There seems also ground for suspecting, in accordance with the suggestion of Dr. Dawson, that the flora of the Devonian rocks of North America was of a more upland character than that of the coal, and the mere fact of our having traced this ancient vegetation (the Devonian and Carboniferous), consisting of several hun- dred species, over so vast an area in space, in Hurope and North America, and through such a lapse of ages, makes it probable that we have already obtained a correct notion of the leading features of the botany, both upland and lowland, of those paleozoic times. The almost entire want in this fossil flora, the first which geology has yet revealed to us, of plants of the most complex organisation is very striking, for not a single dicotyledonous angiosperm has yet been found in any primary formation, and only one undoubted monocotyledon,* although these two great divisions taken together form four- fifths of our living vegetation. In regard to secondary or mesozoic times, all botanists agree that palms, with some other monocotyledons, were already in existence; but it seems doubtful whether any trace of a dicotyledonous angiosperm has yet been detected in rocks of the Triassic, Oolitic, or Lower Cretaceous periods. Conifers, ceycads, and ferns abounded, but the plants which now con- stitute the larger portion of our flora, and comprise all the native Huropean trees except those of the fir tribe, seem not to have come into being, and must certainly have been ex- tremely rare before the Upper Cretaceousera. I+ is in strata of this latter age, at Aix-la-Chapelle, that we at length meet with an assemblage of fossil plants, in which the principal * Pothocites Grantonii, Paterson, from . 1844. This plant, which is the coal shale of Granton near Edin- referred to the family Aroidez, has the burgh. Edin. Bot. Soc. Trans. vol. i. spike well preserved. 150 DEVELOPMENT OF ORGANIC LIFE [Cu. Ix, classes and orders of the living vegetable creation are fully represented. ‘The variety and completeness of the fogsi] flora then attained continued to be conspicuous throughout a lon succession of tertiary ages, in which the forms were perpetually changing, but always becoming more and more like, generically and specifically, to those now in being. On the whole there appears therefore to have been an advance in the fossil flora in the course of ages, although the cryptogamous plants of the primary periods may some of them have been more perfect or of a higher grade than any of the same class now living. The Gymnogens (cycads and conifers) became more abundant, as also the Monocotyledons in the Secondary epochs, while in the Tertiary periods all the leading forms of the most complex dicotyledons now inhabiting the globe appear to have flourished. Fossil Anvmals.—-We may next turn to the animal kingdom, and consider the arguments derived from fossil vertebrata and invertebrata in favour of progressive development. When- ever these arguments are founded on negative evidence, we cannot be too cautious in our reasoning, and we must always bear in mind that it has been evidently no part of the plan of Nature to hand down to us a complete or systematic record of the former history of the animate world. We may have failed to discover a single shell, marine or freshwater, or a single coral or bone in shale or sandstone, even in such a formation as that of the valley of the Connecticut, in which the footprints of bipeds and quadrupeds abound ; but such failure may have arisen, not because the population of the land or sea was scanty at that era, but because in general the preservation of any relics of the animals or plants of former times is the excep- tion to a general rule. Time so enormous as that contemplated by the geologist may multiply exceptional cases till they seem to constitute the rule, and so impose on the imagination as to lead us to infer the non-existence of creatures of which no monuments happen to remain. The late Edward Forbes re- marked, that few geologists are aware how large a proportion of all known species of fossils are founded on single specimens; while a still greater number are founded ona few individuals discovered in one spot. This holds true not only in regard to a Dee é King, tebmi t. We rideng; aust ale the pla ie Tedin hare fi or ai ormalil: e foot re may? 2 wass? tion , the & Cu. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 151 animals and plants inhabiting the land, the lake, and the river, but even to a surprising number of the marine mollusca, articulata, and radiata. Our knowledge, therefore, of the living creation of any given period of the past, may be said to depend in a great degree on what we commonly call chance, and the casual discovery of some new localities rich in pecu- liar fossils may modify, and, to a great extent, overthrow all all our previous generalisations. Mollusca.—Of all the invertebrate animals, the mollusca are the most important in geology, as, owing to the durable nature of their shells, they have been more generally pre- served, in strata of every age, than the memorials of any other creatures. They are also peculiarly well-fitted to throw light on the controverted question whether there has or has not been a gradual advance in the course of ages, from the humbler and more simple to the higher and more complex grades of structure. By a higher or more perfect organisation is meant one in which there are a greater number of organs specially devoted to particular functions. Thus in the lowest divisions, such as the Bryozoa and Brachiopoda, we find no separate organs of respiration, sight, or locomotion ; whereas, in the lamellibranchiate bivalves, although they are without heads, we find a heart, gills, a foot, and several other organs, want- ing in the inferior orders before alluded to. The gasteropoda, again, have a head, mouth, teeth, a special breathing appa- ratus, and nearly all of them organs of sight ; while in the highest grade, the Cephalopoda, we meet with so many in- struments appointed to perform distinct functions, such a concentration of the nervous system in what may be regarded as a brain, such acuteness of the senses, especially that of sight, with such powers of locomotion, that we cannot refuse to assign to them a place superior to that of all the other mollusca, and even to some few species of the vertebrata, although these last belong to a type which as a whole ranks so much higher in the scale. We have now, therefore, to enquire whether the fossil representatives of the different divisions of the mollusca above enumerated, the Bryozoa, Brachiopoda, Lamellibranchiata, Gasteropoda, and Cephalopoda, made their appearance in 152 DEVELOPMENT OF ORGANIC LIFE [Cu. Ix succession in the ancient seas in the same order of time ag they would stand in an ascending series in a zoological claggi- fication. nour endeavour to reply to this question it will be well to exclude from our survey the fossils of the lower str | , | at bi or those older than the Lower Silurian (Nos. 36 and 37 - of the Table, p. 62) with which we are so imperfectly acquainted, ne that 1t 1s dangerous to derive from them any conclusions el founded simply on negative evidence. Additions made from. i year to year may change the whole aspect of this primordial bi fauna of Barrande. Already indeed the notion of its extreme al poverty and inferiority of grade has to some extent had to | re be abandoned by the detection in it of an Orthoceras in ck Sweden. | k To begin with the Lower Silurian (No 35 of the same ¢ table), we find that it contains representatives of all the | g groups to which we have alluded, and the Cephalopoda t ulone have already furnished the conchologist with several | ‘ hundred species and a long list of genera. Many of these chambered shells, especially the Ammonites and Orthocerata, | were of large size, and they may possibly have swarmed the more in the ancient ocean because there were no fishes to | compete with them. It has been remarked by the advocates of * progressive evolution,’ that all the cephalopods of this era | t are referable to the tetrabranchiata, a family which is not so f highly organised as the dibranchiata, to which the belemnites, | g so abundant in the Lias, Oolite, and Chalk, as well as not a 4 few of the living cuttlefish belong. Doubtless the absence of | F all genera of this highest order from the Silurian, Devonian, “ and Carboniferous formations may seem to imply that the tes- d taceous fauna of the older rocks had not yet obtained so high . = a grade as it afterwards reached. But the cogency of such | a reasoning is somewhat weakened by the fact, that several al genera of Octopods now exist in our seas, which are without | internal bones, like those possessed by the Sepia, or ex- | ternal shells, like those of the Nautilus. Such soft-bodied ) : cephalopods, therefore, could not be expected to leave | 4 behind them any lasting memorials of their existence. It is | Q only by assuming that there were no such genera in the | ‘ paleozoic seas, that we can confidently infer a comparative | ‘ Ca. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 153 inferiority of grade for the mollusea of that early period. It has been also remarked, in reference to the testaceous fauna of the primary strata, that while the lamellibranchiate bivalves are comparatively few in number, brachiopods of every variety of form are exceedingly abundant. It can- not be denied that the profusion of these last fixes on this earlier fauna a stamp of inferiority. But if we lay much stress on this argument, we find that it is somewhat counter- balanced by evidence bearing in an opposite direction, and equally derived from the proportional number of the representatives of different orders of mollusca. If the Bra- chiopods outnumber the Lamellibranchiata, so, on the other hand, do the Cephalopods outnumber the Gasteropods, espe- cially the highest division of these last, those which are siphonated, and which as zoophagous, marine animals seem to have been superseded by the Ammonite, Nautilus, and their congeners. In this case, these last, being mollusca of a higher grade, discharged functions now performed toa great extent by Gasteropods, which are lower in the scale. On the whole, it cannot be said that the successive development, in the course of past ages, of higher and more complex struc- tures, is by any means conspicuous in that grand branch of the animal kingdom which is most largely represented in a fossil state. The variety perhaps of types in the testacea 1s ereater now than at any former period, but the rate of advance in organisation has been slow indeed, if the only step realised between Lower Silurian and modern times can be expressed by the passage from a tetrabranchiate to a dibran- chiate cephalopod. According to such a rate of progress, we should require a course of ages anterior to the Silurian epoch as great as that which has since elapsed, in order to bring about a gradual evolution from a bryozoon to an orthoceras. Fossil Fish.—The failure of the paleontologist to detect a single bone of any aquatic animal of the vertebrate class in rocks older than the Ludlow formation of Murchison, one of the uppermost divisions of the Silurian system, is a fact of no small weight in favour of progressive development. We may still hope to trace back the memorials of the great class of fishes to strata of higher antiquity; but when we 154 DEVELOPMENT OF ORGANIC LIFE [Cu. Ix consider how rich a molluscous fauna—to say nothing of the crustaceans, sea-urchins, stone-lilies, and corals—have heey met with in Silurian rocks in almost all parts of the world, it seems impossible to account for our not having yet found any accompanying bones of fish, except by supposing that they were not yet in being, or that they only occupied a limited area. To verify the date of the first appearance of any new type of organisation is perhaps more than we can reasonably expect, as the first representatives of such types probably originate in one spot only, from which they would spread very slowly over the globe. Next to the Silurian comes the Old Red Sandstone or Devonian formation, which is so rich in fishes that the number of British species alone described by Agassiz, in 1844, amounted to sixty-five. Almost all of these belonged to the order of Ganoids, and some few only to that of the Placoids, of Agassiz; and it is remarkable that the vast majority of the fossil fish of the succeeding formations, from the Carboniferous to the Oolitic, consist in like manner of Ganoids, a family which, though so rich in genera in the olden times, is of quite exceptional occurrence in the present crea- tion, being confined to the North-American rivers, and those of Africa north of the line. In. the chalk, and still more i the tertiary formations, we find the majority of the fish to belong to a great variety of genera of the class called Teleostet ecause their skeletons are perfectly ossified, which is very rarely the case with the Ganoids of the older rocks. The cartilaginous, persistent nature of the spinal column oF notochord, which is not divided into separate vertebra, 18 regarded on the whole as a mark of a lower grade, as 18 also the form of the tail called heterocercal, which is almost niversal in fish older than the chalk. Nearly all the living fish have equilobed tails, and the heterocercal or inequilobed form is looked upon by Owen as a retention of the embryonic character, or an instance of arrested development. But the aifinity of the ancient Placoid and Ganoid fishes inthe structure of their heart, brain, generative organs, and many other cha- racters to living sharks, as wellas to the African Polypterus and the bony pike, or Lepidosteus, of America, leads the tions } mane nthed eve Cu. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 155 anatomist to assign to them by no means a low place in the piscine class. In short, a retrospect of the history of this class in geological time ‘imparts,’ according to Professor Owen, ‘ an idea rather of mutation than of progression.’ * Reptiles.—No well-authenticated example of a reptile occurring in strata so old as the Devonian has yet been established,+ and it was not till the year 1844, that some representatives of the lowest division of this class, the am- phibia, which are regarded by some naturalists as Interme- diate between reptiles and fish, were discovered in the coal of Saarbruck. Since that period several genera of the Labyrinthodont family, some containing species of large size, have been found in the carboniferous rocks of North America and Britain. So late as 1865, four or five new genera of this family determined by Professor Huxley have been added from the coal of Tipperary in Ireland. Some of these have well-ossified bony skeletons, although they belong to that sub-class which, like the frogs and newts, possessed gills at some period of their existence, and were also marked by other piscine characters. In rocks of later age, from the Triassic to the Cretaceous inclusive, there is an extraordinary profusion of reptile life, to which I shall have occasion to allude again in the eleventh chapter. Some of the orders, especially the Dinosaurians, are of so high a grade as to be more akin to the mammalia than are any reptiles of later date, whether tertiary or living; so that we have here an example of a class which gradually advanced till it reached a culmi- nating point, from which it has ever since been retrograding. The period of the degeneracy or degradation of this class seems to have coincided with that of the first appearance on the globe of the placental, or most perfect of the mammalia. Scarcity of atr-breathers in primary rocks.—Our infor- mation respecting the fossils of the oldest rocks, especially those anterior to the Old Red Sandstone or Devonian formation, is almost exclusively derived from strata of marine origin. This we might have anticipated, if the ocean always occupied, as it does now, nearly five parts in seven of * Owen’s Paleontology, 2nd edit. p. +See Elements of Geology, 6th Edi- 175. tion, p. 526 note. 156 DEVELOPMENT OF ORGANIC LIFE [Cur, EX, the earth’s surface. After many geographical revolutions, after the sinking down of ancient continents and the Up heaval of newer ones, it is natural that the strata of very remote age should coincide generally with the bed of the ancient ocean, rather than with the space which was occupied by land. The reader will perhaps be better able to appreciate the difficulty which, according to the doctrine of chances, will usually attend a search for the fossil memorials of the inhabitants of ancient lands—those, for example, of the primary periods—if he glances at the map, fig. 12, p. 258. He will here observe that the areas distinguished by dark shading, represent the only spots on the globe where there is now land exactly opposite to land. Let us imagine these dark spots, instead of expressing the site of contemporaneous antipodal land, to represent the spaces where paleozoic land of Silurian or Cambrian date may have happened to coincide with a portion of our present continents and islands. The amount of such coincidence must strike the reader as limited in the extreme ; but its amount is by no means improbable, for the contrast of two opposite hemispheres, in regard to the distri- bution of land and sea, at one and the same time, would on he average resemble the contrast which in reference to such distribution would characterise the same hemisphere in two very distant ages. Well therefore may we despair of gaining more than a superficial acquaintance with the terrestrial plants and air-breathing animals which once belonged to those small shaded areas. If they had never been submerged from the earliest period, they would have suffered such denudation by rain and rivers, both when the land was stationary or when it was undergoing changes of level, that no parts of the old surface, or of its lacustrine and fluviatile deposits, would remain. Our best chance of hitting upon the spots where some monuments of such early times have escaped destruction, would arise from the submergence of the shaded spots, and the accumulation of marine strata upon them or upon the littoral deposits found in the immediate neighbourhood. Even then we could only obtain access to the buried strata, whether fresh-water or littoral, at those points where they had been exposed to view by the partial “< fh, Cu. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 157 waste of the incumbent formations. The general absence therefore in Cambrian, Silurian and Devonian rocks of all remains of land animals is not to be wondered at, and taken alone affords no presumption against the existence, in paleozoic times, of air-breathers of the most highly organised class. Up to the year 1865, only a few insects had been obtained even from the Carboniferous strata, the land plants of which are well known to us, and none from the Devonian. From this last formation several have now been brought to light +1 North America, chiefly of the order Newroptera, found by Mr. Hartt, in rocks near St. J ohn’s, New Brunswick, and determined by Mr. Scudder, of Boston, U.S. Why then should we despair of finding in our future researches, some air-breathers of a much higher order than insects which may have peopled the forests of the Devonian era, in which pines, Sigillariz and Lepidodendra, or gigantic Lycopodiaceze flourished. The first pulmoniferous mollusk, a land shell, called Pupa Vetusta, of which hundreds of individuals have now been detected, was not discovered in the coal measures until the year 1852, in Nova Scotia. Birds.—In regard to birds, they are usually wanting, for reasons to be explained in the next volume, in deposits of all ages, even in the tertiary periods, where we know that birds as well as land quadrupeds abounded. Some of the fossil remains formerly referred to this class in the Wealden (a erveat freshwater deposit below the chalk), have since been shown to belong to pterodactyls.* But in the lithographic stone of Solenhofen, a division of the Upper Oolite, a skeleton of a bird almost entire, and retaining even some of its feathers, was found in 1862, and determined by Professor Owen to belong to the class Aves. It differs from all living birds in the structure of its fore limbs and still more of its tail, in which last there were no less than twenty vertebra, each of them supporting a pair of plumes. Although no skeletons of the feathered tribe have been found in rocks older than the Oolite, yet the footmarks of a great variety of species, of va- rious sizes, some larger than the ostrich, others smaller than * Quart. Journ. Geol. Soc. No. 6, p. 96. 158 DEVELOPMENT OF ORGANIC LIFE [Cu Ix, the plover, have been observed in rocks of higher antiquity in North America.* These bipeds have left the marks of their footsteps on strata of Triassic age in the valley of the Connecticut, and they are useful in warning us against spe- culating on the relative grade of ancient and modern repre- sentatives of this class, seeing that, although there were 80 many of these bipeds, we are so ignorant of their structure. Hitherto, even footprints of the class Aves have eluded oyp search in all formations older than the Trias, so that we ma declare at present that the first appearance of fish, reptiles, and birds, follows a chronological order in accordance with the position which the same classes would occupy when ar- ranged zoologically by a naturalist in an ascending Series ; and we shall presently see that the lowest class of Mammalia have not yet been traced back so far as the footprints of the earliest known birds. Mammalia.—So late as the beginning of the present cen- tury it was a generally received dogma in geology that the Mammalia had not been created before the Tertiary period, and the first announcement of the discovery in the Lower Oolite of Stonesfield, of the jaw of a small marsupial, recog- nised as such in 1818 by Cuvier, caused a sensation almost as great as would now be excited by our finding the bones of some quadrumanous animal in one of the Secondary rocks. Many naturalists, rather than allow their faith in the theory of progressive development to be so rudely shaken, cherished to the last a hope that it might ultimately turn out that the British geologists had been mistaken in their opinion as to the age of the deposit in which this precious relic was e- tombed : while other eminent anatomists, M. Blainville among the number, called in question the mammalian character of the relic. But no less than nine other specimens of lower jaws of mammiferous quadrupeds have since been met with in the same slate of Stonesfield, so that, including the first found (fig. 3, p. 159), there are now four distinct species referable to three genera in this one member of the Lower Oolite. After Cuvier had referred the specimen first met with to ® * See Hitchcoek’s Report on Geol. of Massachusetts, and Lyell’s Travels in North America, chap. 12. a =) | | | | | | | | | | | | | Cu. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 159 marsupial, Professor Owen pointed out that the extinct genus to which it belonged had considerable affinity to an Austra- Thylacotherium Prevostii (Valenciennes). Natural size. Amphitherium (Owen). Lower jaw, from the slate of Stonesfield, near Oxford.* lian mammifer, the Myrmecobius of Waterhouse, which has nine molar teeth in the lower jaw (see fig. 4). Fig. 4. Myrmecobius fasciatus (Waterhouse). Recent from Swan River. Lower jaw of the natural size.T The next representative of the same class found in the same slate was at once regarded as an opossum, with which it agrees nearly in osteological character, and precisely in the number of its teeth (fig. 5, p. 160). But the most remark- able of all the mammalia of which the remains have been found at Stonesfield, was that made known to the scientific itis sunk. The form of the condyle, or posterior process of the jaw, 1s convex, i ith the being characteristic of the mammalia. Ten molars are preserved, and the place of an eleventh is believed to be appa- rent. The enamel of some of the teeth is well preserved. A coloured figure of this small and elegant quadruped is given in the Trans. Zool. Soe. vol. ii. pl . It is insect- ivorous, and was taken in a hollow ree, in a country abounding in ant- hills, ninety miles to the south-east of the movth of Swan River in Australia. lower jaw, andsome of the teeth are 160 DEVELOPMENT OF ORGANIC LIFE [Cu. Ix, world in 1854, called Stereognathus,* consisting of part of 7 lower jaw containing three double-fanged teeth, indicating Fig. 5. Natural size. Phascolotherium Bucklandi (Owen). (Syn. Didelphis Bucklandi, Brod.) Lower jaw, from Stonesfield.f J 1 The jaw magnified twice in length. 2 The second molar tooth magnified six times. JAW OF STEREOGNATHUS, FROM STONESFIELD. a. Portion of jaw with three molar teeth from Stonesfield oolite. Natural size. ( Owen’s Paleontology, p. 845.) 0. Middle tooth of the three contained in the jaw a. ( Owen, Ibid., p. 346.) an animal small in size, but larger than any of the contem- | oS A widely separated from others, one of the peculiarities in the Thylacotherium M. Blainville to refer that creature to the class of reptiles. * This generic name was given to it in 1854, by Mr. Charlesworth, who ob- tained it from the Rey. J. P. Dennis, in whose possession it had been for twenty years or more. ~ This figure (No. 5) was taken from the original, ‘formerly in M Broderip’s collection, and now in the British Museum. It consists of the = =) right half of a lower jaw, of which the inner side is seen. The jaw contams seven molar teeth, one canine, and three incisors; but the end of the jaw 18 would agree exactly ib oqinos vol. iii. p. 408. Owen, Proceedings Geol. Soe., Noyember, 1838. £3 Dal a5 ~ Cu. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 161 porary quadrupeds as yet obtained from the same rocks. (See o. 6. aoe the teeth differed in structure from those of any recent or fossil animal yet known, they are admitted by ana- tomists to have more affinity to the higher or placental division of the mammalia than any of the species previously found at Stonesfield, or those yet procured from any rocks older than the Tertiary. It is conjectured by Professor Owen that it may have been a small, hoofed, herbivorous animal, but he still regards this conclusion as very doubtful; so far does Stereognathus depart from any known type whether living or extinct. When the Stonesfield oolite had continued for nearly thirty years to be the only rock which had in any part of the world afforded an example of a fossil mammifer anterior in date to the Tertiary period, the tooth of another small mammifer, called Microlestes, was discovered in the Upper Trias of Stuttgardt in 1847.* Between that year and 1863 this rock and the Upper Trias of Somersetshire, and a stratum probably of about the same age in North Carolina, have sup- plied us with the jaws and teeth of two or three species of diminutive marsupials. The only other mammalia as yet discovered in any other part of the globe in formations older than the Hocene, are those of the Uppermost Oolite or Pur- beck strata in Dorsetshire, where about fourteen species, referable to about eight genera, have been met with, all very small, most of them decidedly marsupial, and the rest, if not of the same sub-class, belonging to insectivora of low grade.t+ It may, no doubt, be said that our acquaintance with the purely freshwater strata of periods older than the Secondary is very defective, and that we ought therefore to expect that memorials of land animals in marine strata of Primary or Pa- leozoic date would be very exceptional. There are regions at . present, in the Indian and Pacific Oceans, coextensive in area with Kurope and North America, where we might dredge the bottom and draw up thousands of shells and corals, without obtaining one bone of a land quadruped. Suppose our mari- ners were to report, that, on sounding in the Indian Ocean * Elements, pp. 430-440. t See Elements, p. 383. iO bh. 162 DEVELOPMENT OF ORGANIC LIFE [Cu, Ix near some coral reefs, and at some distance from the land, they drew up on hooks attached to their line portions of an ape, elephant, or leopard, should we not be sceptical as to the accuracy of their statements? and if we had no doubt of their veracity, might we not expect them to be unskilfy] naturalists? or, if the fact were unquestioned, should we not be disposed to believe that some vessel had been wrecked on the spot ? The casualties must always be rare by which land quadru- peds are swept by rivers far out into the open sea, and still rarer the contingency of such a floating body not being devoured by sharks or other predacious fish, such as were those of which we find the teeth preserved in some of the carboniferous strata. But if the carcass should escape, and should happen to sink where sediment was in the act of accumulating, and if the numerous causes of subsequent disintegration should not efface all traces of the body, in- cluded for countless ages in solid rock, it would be contrary to all calculation of chances that we should hit upon the exact spot—that mere point in the bed of an ancient ocean, where the precious relic was entombed. Can we expect for a moment, when we have only succeeded, amidst several thousand fragments of corals and shells, in finding a few bones of aquatic vertebrata, that we should meet with a single skeleton of an inhabitant of the land ? Clarence, in his dream, saw ‘in the slimy bottom of the deep,’ a thousand fearful wrecks ; A thousand men, that fishes gnaw’d upon ; Wedges of gold, great anchors, heaps of pearl. Had he also beheld, amid ‘ the dead bones that lay scattered by,’ the carcasses of lions, deer, and the other wild tenants of the forest and the plain, the fiction would have been deemed unworthy of the genius of Shakspeare. So daring a disregard of probability and violation of analogy would have been condemned as unpardonable, even where the poet was painting those incongruous images which present them- selves to a disturbed imagination during the visions of the night. ———— we — Cx. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 163 Absence of cetacea im secondary rocks.—But there igs a negative fact of great significance which seems more than any other to render it highly improbable that we shall ever find air-breathers of the highest class in any of the primary strata, or in any of the older members of the secon- dary series. This fact is the absence hitherto of all bones of cetacea among the numerous remains of fossil vertebrata entombed in rocks older than the Eocene. Cetacean bones are of rare occurrence in the Lower Tertiary formations of Europe, the only instance in Great Britain being a species of Monodon from the London clay, and the position even of this specimen is somewhat doubtful. But in the middle Eocene of America, as in Georgia and Alabama, the gigantic Zeuglodon, now admitted to be a true placental mammal, is by no means of uncommon occurrence.* A series of anchylosed cervical vertebrae of a whale found near Ely, in Cambridge- shire, is supposed by Professor Sedgwick to have been derived from some member of the Oolite; but as it was not obtained from a rock im situ, but from argillaceous drift into which it had been washed, we must regard its true age as a ques- tion still unsettled. The dimensions of the cetacea in general are such that they could hardly have failed to obtrude them- selves on the notice of collectors had they been entombed in the mud and sand of Triassic, Liassic, or other secondary formations where the skeletons of huge reptiles are so con- spicuous. The ichthyosaurs and other carnivorous saurians seem formerly to have played the part now assigned to the cetacea in the economy of nature; and if we assume this to have been the case, it seems probable that the placental mammalia, if they existed at all before the ey period, were at least extremely scarce. Successive appearance in chronological order of the great sub- classes of mammalia of higher and higher grade.—In a classifi- cation of mammalia, founded on the modification of their cere- bral structure, Professor Owen has assigned the lowest place * The 's et cetaceans of the lately been ascertained by him to be of cretaceous rocks, which I formerly cited Miocene date.—Leidy, Reptiles of the on the authority = Dr. Liedy, have alk, M 2 164 DEVELOPMENT OF ORGANIC LIFE (Cu, TX. to asub-class called Lyencephala, which comprises two orders, the Marsupialia and the Monotremata. In this last are ind cluded the Echidna (or duckbilled Platypus) of Australia and the Ornithorhynchus of the same continent. No members of this lowest division of the mammalia have yet been found fossil, but we ought to look for their remains in the Car- boniferous and other primary rocks, should air-breatherg higher than the class of reptiles ever be discovered in them, assuming that a thorough knowledge of the succession in time of the fossil vertebrata would bear out fully the theory of progressive development from the simplest to the most complex types. We should then have monotremata in the Primary, marsupials in the Secondary, and placentals in the Tertiary strata, assuming for the present that the class to which Stereognathus belongs is still undetermined. In the history of the Tertiary and Post-tertiary series, it may be said that there is in the mammalia a still farther evo- lution from the less to the more perfect structures. For the earliest known species of the placental sub-class does not belong to the Quadrumanous order, the most ancient represen- tative of that type being the Arctocyon primevus, which has been met with in France in Eocene strata older than the Plastic clay or Woolwich beds. Of later date than this, M. Riitimeyer has recognised, in a member of the Middle Eocene eroup of the Swiss Jura, the jawbone of a monkey allied in some points to the Mycetes or howling monkey of America and in others to the Lemurs. If this determination be con- firmed when more of the skeleton has been discovered, the Ceenopithecus lemuroides would constitute the oldest known example of a fossil quadrumanous animal.* The next step occurs in the Upper Miocene or Falunian deposits of Europe, in which several examples of the monkey tribe have been met with, and among them some of the anthropomorphous apes. One of them, the Dryopithecus, allied to the Guib- * The fossil monkey named Macacus nounced. by the same anatomist in 1862, Eocenus by Owen, found in 1840, at to be a pachyderm, more ample data for on, near Ipswich in Suffolk, in a its correct determination haying been stratum older than the London aie and obtained, Thevery questionable authen- which I formerly cited as quadrumanous _ ticity of a cote piss British monkey on the authority of Prof. Owen, was pro- will be alluded to (p. 194). ——A. Cu. IX.] AT SUCCESSIVE GEOLOGICAL “PERIODS. 165 bon, discovered in the South of France, rivalled man in stature. If in the Pliocene strata, which followed next in the order of time, no quadrumana have been detected, we may attribute their absence to the diminished warmth of the Pliocene climate, which began to resemble that now enjoyed in the south of Hurope, instead of being, like that of the Upper Miocene, sub-tropical. For evidence of the gradual development of the monkeys, apes, and orangs, and of the first appearance of man, the progressionist will natu- rally look to those countries which escaped the rigours of the Glacial Period, whereas our most careful investigations have hitherto been confined to the temperate latitudes of the northern hemisphere, whether in the Old or New World. However slender therefore may be the foundation of facts on which such grand generalisations are built, and however anxious we may be not to place too much reliance on the soundness of our inferences, we may yet say that the direction in which the facts point are decidedly towards the theory of progression. We have been fairly led by paleontological researches to the conclusion that the invertebrate animals flourished before the vertebrata, and that in the latter class fish, reptiles, birds, and mammalia made their appearance in a chronological order analogous to that in which they would be arranged zoologically according to an advancing scale of perfection in their organisation. In regard to the mammalia themselves, they have been divided by Professor Owen into four sub-classes by reference to modifications of their brain. In the two low- est, called Lyencephala and Lissencephala, are included the marsupials and insectivora, and these have been met with fossil in the secondary rocks. Next above them in grade are the Gyrencephala, in which Cetaceans, Proboscidians, Rumi- nants, Carnivora, and Quadrumana are classed, all of which are found fossil in tertiary strata. Among these the Quadrumana rank highest, and the Anthropomorphous family takes the lead in organisation and instinct among the Quadrumana, coming also last in the order of time. To crown the whole, the series ends with the fourth great sub-class, the Archen- cephala, of which man is the sole representative, and of which 166 DEVELOPMENT OF ORGANIC LIFE [Cu. IX, the fossil remains have not yet been detected in deposits older than the post-tertiary. Antecedently to investigation, we might reasonably have anticipated that the vestiges of man would have been traced back at least as far as those Pliocene strata in which nearly all the testacea and a certain number of the mammalia are of existing species, for of all the mammalia the human species is the most cosmopolite, and perhaps more capable than any other of surviving considerable vicissitudes in climate, and in the physical geography of the globe. No inhabitant of the land exposes himself to go many dangers on the waters as man, whether ina Savage or a civilised state; and there is no animal, therefore, whose skeleton is so liable to become imbedded in lacustrine or gub- marine deposits: nor can it be said that his remains are more perishable than those of other animals; for in ancient fields of battle, as Cuvier has observed, the bones of men have suffered as little decomposition as those of horses which were buried in the same grave. But even if the more solid parts of our species had disappeared, the impression of their form might have remained engraven on the rocks, as have the traces of the tenderest leaves of plants, and the soft integuments of many animals. Works of art, moreover, composed of the most indestructible materials, would have outlasted almost all the organic contents of sedimentary rocks. Hdifices, and even entire cities, have, within the times of history, been buried under volcanic ejections, sub- merged beneath the sea, or engulphed by earthquakes; and had these catastrophes been repeated throughout an indefinite lapse of ages, the high antiquity of man would have been inscribed in far more legible characters on the framework of the globe than are the forms of the ancient vegetation which once covered the islands of the northern ocean, or of those gigantic reptiles which at still later periods peopled the seas and rivers of the northern hemisphere. Dr. Prichard has argued that the human race have not always existed on the surface of the earth, because the ‘ strata of which our continents are composed were once a part of the ocean’s bed ’—‘ mankind had a beginning, since we can look —s a —sew Cu. IX. ] AT SUCCESSIVE GEOLOGICAL PERIODS. 167 back to the period when the surface on which they lived began to exist.* This proof, however, is insufficient, for many thou- sands of human beings now dwell in various quarters of the globe where marine species lived within the times of history, and, on the other hand, the sea now prevails permanently over large districts once inhabited by thousands of human beings. Nor.can this interchange of sea and land ever cease while the present causes are in existence. Terrestrial species, therefore, might be older than the continents which they inhabit, and aquatic species of higher antiquity than the lakes and seas which they now people. Introduction of Man, to what extent a change of the system. _—_I shall defer to the next volume the discussion of a theo- retical question of surpassing interest with which the paleon- tologist has been busily engaged ever since the time of La- marck, namely, whether it is conceivable that each fossil fauna and flora brought to light by the geologist may have been con- nected, by way of descent or generation, with that which im- mediately preceded it, our record being so defective that nearly all the intermediate links by which a transition was effected from genus to genus, or from species to species, have in most cases left behind them no vestiges of their former existence. In support of this opinion, it has been argued that the earliest remains of man imply a rude state of the arts and an entire ignorance of the use of metals. On the other hand, little or no progress has been made in discovering fossil remains which indicate any inferiority in the cerebral development of man in the paleolithic era. It may fairly be argued that the superiority of man depends, not on those faculties and attri- butes which he shares in common with the lower animals, but on his reason, by which he is distinguished from them. When it is said that the human race is of far higher dignity than were any pre-existing beings on the earth, it is the in- tellectual and moral attributes of our race, rather than the physical, which are considered; and it is by no means clear that the organisation of man is such as would confer a de- cided pre-eminence upon him, if, in place of his reasoning powers, he was merely provided with such instincts as are * Phys. Hist. of Mankind, vol. ii, p, 594, 168 DEVELOPMENT OF ORGANIC LIFE [Cu. IX, possessed by the lower animals. It may also be questioned whether the passage from an irrational to a rational animal] is not a phenomenon of a distinct kind from the passage froin the more simple to the more perfect forms of animal organi- sation and instinct. Without entering at present into the discussion of this and other cognate questions which lie almost beyond the domain of science, we may endeavour to answer an objection which has been made to the doctrine of the past uniformity of nature. Is not the interference of the human species, it is asked, such a deviation from the antecedent course of physical events, that the knowledge of such a fact tends to destroy all our confidence in the uniformity of the order of nature, both in regard to time pastand future? If such an innovation could take place after the earth had been exclusively inhabited for thousands of ages by inferior animals, why should not other changes as extraordinary and unprecedented happen from time to time? If one new cause was permitted to supervene, differing in kind and energy from any before in operation, why may not others have come into action at different epochs ? Or what security have we that they may not arise hereafter? And if such be the case, how can the experience of one period, even though we are acquainted with all the possible effects of the then existing causes, be a standard to which we can refer all natural phenomena of other periods ? Now these objections would be unanswerable, if adduced against one who was contending for the absolute uniformity throughout all time of the succession of sublunary events—if, for example, he was disposed to indulge in the philosophical reveries of some Eeyptian and Greek sects, who represented all the changes both of the moral and material world as re- peated at distant intervals, so as to follow each other in their former connection of place and time. For they compared the course of events on our globe to astronomical cycles ; and not only did they consider all sublunary affairs to be under the influence of the celestial bodies, but they taught that on the earth, as well as in the heavens, the same identical pheno- mena recurred again and again in a perpetual ‘-vicissitude. The same individual men were doomed to be re-born, and t0 Cu. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 169 perform the same actions as before; the same arts were to be invented, and the same cities built and destroyed. The Argonautic expedition was destined to sail again with the same heroes, and Achilles with his Myrmidons to renew the combat before the walls of Troy. Alter erit tum Tiphys, et altera quae vehat Argo Dilectos heroas ; erunt etiam altera bella, Atque iterum ad Trojam magnus mittetur Achilles.* The geologist, however, may condemn these tenets as ab- surd, without running into the opposite extreme, and denying that the order of nature has, from the earliest periods, been uniform in the same sense in which we believe it to be uni- form at present, and expect it to remain so in future. We have no reason to suppose, that when man first became master of a small part of the globe, a greater change took place in its physical condition than is now experienced when districts, never before inhabited, become successively occupied by new settlers. When a powerful European colony lands on the shores of Australia, and introduces at once those arts which it has required many centuries to mature; when it imports a multitude of plants and large animals from the opposite extremity of the earth, and begins rapidly to extirpate many of the indigenous species, a mightier revolution is effected in a brief period than the first entrance of a savage horde, or their continued occupation of the country for many centuries, can possibly be imagined to have produced. If there be no impropriety in assuming that the system is uniform when disturbances so unprecedented occur in certain localities, we can with much greater confidence apply the same language to those primeval ages when the aggregate number and power of the human race, or the rate of their advancement in civi- lisation, must be supposed to have been far inferior. In rea- soning on the state of the globe immediately before our species was called into existence, we must be guided by the same rules of induction as when we speculate on the state of America in the interval that elapsed between the introduction * Virgil, Eclog. iv. For an account Human Mind, vol. ii. chap. 1. sect. 4, ofthese doctrines, see Dugald Stewart’s and Prichard’s Egypt. Mythol. p. 177. Elements of the Philosophy of the 170 DEVELOPMENT OF ORGANIC LIFE, [Cu. IX, of man into Asia, the supposed cradle of our race, and the arrival of the first adventurers on the shores of the New World. In that interval, we imagine the state of things to have gone on according to the order now observed in regions unoccupied by man. Hven now, the waters of lakes, seas, and the great ocean, which teem with life, may be said to have no immediate relation to the human race—to be portions of the terrestrial system of which man has never taken, nor ever can take possession; so that the greater part of the in- habited surface of the planet may still remain almost ag in- sensible to our presence as before any isle or continent was appointed to be our residence. If the barren soil around Sydney had at once become fer- tile upon the landing of our first settlers; if, like the happy isles whereof the poets have given us such glowing descrip- tions, those sandy tracts had begun to yield spontaneously an annual supply of grain, we might then, indeed, have fancied alterations still more remarkable in the economy of nature to have attended the first coming of our species into the planet. Or if, when a volcanic island like Ischia was, for the first time, brought under cultivation by the enterprise and industry of a Greek colony, the internal fire had become dormant, and the earthquake had remitted its destructive violence, there would then have been some ground for specu- lating on the debilitation of the subterranean forces, when the earth was first placed under the dominion of man. But after a long interval of rest, the voleano bursts forth again with renewed energy, annihilates one half of the inhabitants, and compels the remainder to emigrate. The course of na- ture remains evidently unchanged; and, in like manner, we may suppose the general condition of the globe, immediately before and after the period when our species first began to exist, to have been the same, with the exception only of man’s presence. The modifications in the system of which man is the im- strument do not, perhaps, constitute so ereat a deviation from previous analogy as we usually imagine; we often, for eX- ample, form an exaggerated estimate of the extent of our power in extirpating some of the inferior animals, and causing acemmaniiiias.. aim, Cu. IX.] AT SUCCESSIVE GEOLOGICAL PERIODS. 173 others to multiply; a power which is circumscribed within certain limits, and which, in all likelihood, is by no means exclusively exerted by our species.* The growth of human population cannot take place without diminishing the num- bers, or causing the entire destruction, of many animals. The larger beasts of prey in particular give way before us; but other quadrupeds of smaller size, and innumerable birds, in- sects, and plants, which are inimical to our interests, increase in spite of us, some attacking our food, others our raiment and persons, and others interfering with our agricultural and horticultural labours. We behold the rich harvest which we have raised by the sweat of our brow, devoured by myriads of insects, and are often as incapable of arresting their de- predations, as of staying the shock of an earthquake, or the course of a stream of lava. A great philosopher has observed, that we can command nature only by obeying her laws; and this principle is true even in regard to the astonishing changes which are super- induced in the qualities of certain animals and plants by domestication and garden culture. I shall point out in the next volume that we can only effect such surprising alter- ations by assisting the development of certain instincts, or by availing ourselves of that mysterious law of their organi- sation, by which individual peculiarities are transmissible from one generation to another.t It is probable from these and many other considerations, that as we enlarge our knowledge of the system, we shall be- come more and more convinced, that the alterations caused _by the interference of man deviate far less from the analogy of those effected by other animals than is usually supposed.{ We are often misled, when we institute such comparisons, by our knowledge of the wide distinction between the instincts of animals and the reasoning power of man; and we are apt hastily to infer, that the effects of a rational and irrational species, considered merely as physical agents, will differ almost as much as the faculties by which their actions are directed. It is not, however, meant by the foregoing observations * See Ch. XLII t See Ch. XXXVIIL, XXXIX., KL., XLIL + See Ch, XXXVI. 172 DEVELOPMENT OF ORGANIC LIFE (Cu. IX, to convey the idea, that a real departure from the ante. cedent course of physical events cannot be traced in the introduction of man. If that latitude of action which enableg the brutes to accommodate themselves in some measure to accidental circumstances could be imagined to have been at any former period so great, that the operations of instinct ; were as much diversified as are those of human reason, it might, perhaps, be contended, that the agency of man did not constitute an essential deviation from the previously es- tablished order of things. It might then have been said, that the earth’s becoming at a particular period the residence of human beings, was an era in the moral, not in the physical world—that our study and contemplation of the earth, and the laws which govern its animate productions, ought no more to be considered in the ight of a disturbance or devi- ation from the system, than the discovery of the satellites of Jupiter should be regarded as a physical event affecting those heavenly bodies. Their influence in advancing the progress of science among men, and in aiding navigation and com- merce, was accompanied by no reciprocal action of the human mind upon the economy of nature in those distant planets; and so the earth might be conceived to have become, ata certain period, a place of moral discipline and. intellectual improvement to man, without the slightest derangement of a previously existing order of change in its animate and inan- imate productions. The distinctness, however, of the human from all other species, considered merely as an efficient cause in the physi- cal world, is real; for we stand ina relation to contemporary species of animals and plants widely different from that which other irrational animals can ever be supposed to have held to each other. We modify their instincts, relative num- bers, and geographical distribution, in a manner superior in degree, and in some respects very different in kind, from that in which any other species can affect the rest. Besides, the progressive movement of each successive generation of men causes the human species to differ more from itself in powe! at two distant periods, than any one species of the higher order of animals differs from another. The establishment, — acc, tt inona Cu. IX.] AT SUCCESSIVE: GEOLOGICAL PERIODS. 173 a therefore, by geological evadence, of the first intervention of such a peculiar and unpretedented agency, long after other parts of the animate and inanimate world existed, affords eround for concluding that the experience during thousands of ages of all the events which may happen on this globe, would not enable a philosopher to speculate with confidence - concerning future contingencies. If, then, an intelligent being, after observing the order of events for an indefinite series of ages, had witnessed at last so wonderful an innovation as this, to what extent would his belief in the regularity of the system be weakened }—would he cease to assume that there was permanency in the laws of nature 2—would he no longer be guided in his speculations by the strictest rules of induction? To these questions it may be answered, that, if he had previously assumed that in the law which regulated the succession of beings in the ani- mate world, there was no tendency to progress in organisa- tion, instinct, and intelligence, he would be called wpon to modify his opinion. But his reliance need not be shaken in the unvarying constancy of the laws of nature, or in his power of reasoning from the present to the past in regard to the changes of the terrestrial system, whether in the organic or inorganic world. 174 CHAPTER X. FURTHER CONSIDERATION OF THE AGREEMENT OF THE ANCIENT AND MODERN CAUSES OF CHANGE—VICISSITUDES IN CLIMATE, ARGUMENTS DERIVED FROM FORMER DIFFERENCES IN CLIMATE—THE REALITY SUCH FORMER DIFFERENCES CONSIDERED—CLIMATE OF THE AGES 0 ERRATIC BLOCKS OF UPPER MIOCENE AND MIDDLE EOCENE CONGLOMERATES, Climate of the Northern Hemisphere formerly different.—AN- OTHER objection to the theory which endeavours to explain all geological changes by reference to causes now in action is founded on the former prevalence of climates hotter than those now experienced in corresponding latitudes. We have seen (p. 42) that Hooke, about the year 1688, grounded his belief in the reality of the higher temperature of the waters of the ancient sea on the occurrence of fossil turtles and ammonites in the Portland oolite. In later times the shells and corals of the Lower Tertiary, and of many of the Secon- dary formations, were appealed to as confirmatory of the same conclusions, while the botanist referred to the character of the fossil flora of the ancient carboniferous rocks as favour- able to the same doctrine. All indications of a high tem- cous Cu. X.] FORMER VICISSITUDES OF CLIMATE, 175 perature recognised in the older formations were regarded with the more favour because they seemed to lend support to the hypothesis of the primeval igneous fusion of the planet, the mass of which, while it radiated heat into the surround- ing atmosphere and ocean, had gradually cooled, and had been constantly acquiring a thicker crust. Since I first attempted, in the year 1830, to account for vicissitudes of climate by reference to changes in the physical geography of the globe,* our knowledge of the subject has ereatly increased, and the problem to be solved has assumed a somewhat new aspect. More extended observations have shown that in times past the climate of the extra-tropical regions has by no means been always hotter than now, but, on the contrary, there has been at least one period, and one of very modern date geologically speaking, when the tempe- rature of those regions was much lower than at present. It will be desirable, therefore, before entering into a discussion of the probable causes of the changes of temperature which have been experienced since the earliest of the fossiliferous rocks were formed, to lay before the reader a brief account of the evidence by which the reality of such changes has been established. At first sight it may seem to be the simplest way of dealing with this subject to begin with a description of the proofs deduced from organic remains of the state of things in very remote times, and then to pass on to successive variations in climate manifested by the fauna and flora of later epochs. But such a method is impracticable, for not only are all the animals and plants found fossil in the oldest rocks specifically distinct from those now living, but a large part of the genera and even the orders to which they belong have for ages ceased to exist. Consequently, when we attempt to make such a comparison with the view of determining the difference of the climates which prevailed at two distant periods, we find it almost impossible to apply the rules derived from the study of the present state of the animate world to another which differed from it so widely. The thread of induction seems broken, and we become convinced that in order to make good * Principles of Geology, Ist edition. 1830, 176 CLIMATE OF AGES OF BRONZE AND OF STONE. [Cu. X our ground, and to reason securely from the known to the unknown, we must first ascertain the relation which the present organic creation bears to that of the period imme- diately antecedent, and then carry back our retrospect step by step to formations of older date. In adopting this course we have the advantage of comparing, in the first instance, the "species now in being, of which the habits and physiological characters are known, with the animal and vegetable remains entombed in the Tertiary formations, in which, as we have seen in the last chapter, all the classes of animals and plants are represented in proportions very analogous to those now prevailing. By this means we escape the danger of one source of error, namely, that of ascribing the predominance of certain genera or families to a difference in climate which in reality may have depended not on temperature but on the absence of competing tribes of higher grade, which, accord- ing to the law of progressive development, had not yet made their appearance on the earth. Climate of the Ages of Bronze and of Stone.—In pursuance, then, of this method of enquiry, we may consider, in the first place, the climate of Europe in times immediately anterior to the historical. We there find no indications of any marked divergence from the present condition of things, whether in the memorials of the age of bronze or in those of the Neolithic stone age,* which preceded it, namely, that to which the Danish kitchen-middens and many of the Swiss lake dwellings belonged. It is evident that the plants and animals which co- existed with man in those ages were identical with species now living in the same countries, with the exception of a few known to have been locally extirpated in historical times. The next antecedent era of which we have acquired any information, is that designated by M. Lartet ‘the Reindeer period,’ when that northern animal extended its range to the foot of the Pyrenees, together with several others fitted for a cold climate. The mammoth and cave-lion quadrupeds, * Sir John Lubbock, in his ‘Prehisto- — stone; calling the older stone neriod, that . , 5 Times, p. 8, has proposed the term in which man was contemporar +r . . ° . . : nt ‘ Neolithic’ for this more moderna age of many extinct mammailia, ‘ Paleolithic. y with cu. X.] CLIMATE OF AGES OF BRONZE AND OF STONE. 177 more characteristic of an anterior period, have been found sparingly in this fauna, and another extinct quadruped, the Irish elk or gigantic deer.* 'The weapons then in use by man show a side state of the arts, and complete ignorance of the use of metals. Passing over this intermediate period, which is as yet but vaguely and imperfectly defined, we come to the older stone age, or ‘ Paleolithic Period,’ comprising the ancient river-gravels of Amiens and Abbeville in France, and of Salisbury and Bedford in England, and the drift of many other parts of Hurope. Here, for the first time in our retro- spect, we encounter the bones of a large number of extinct quadrupeds, such as the elephant, rhinoceros, bear, tiger, and hyena, associated with the remains of living animals and of man. The human relics consist almost entirely in North- western Hurope of unpolished flint implements of a type different from those of the later or Neolithic era, im- plying a less advanced state of civilisation. The gravels containing such works of art and bones of extinct animals belong to a time when the physical geography was unequi- vocally different from that now characterising the same ‘part of Hurope, a discordance which does not hold true of the more modern or Neolithic times. The valleys of the more ancient of the two periods had not acquired their pre- sent width, depth, and outline. The contemporary cavern deposits, in which similar flint weapons and the bones of the same class of mammalia occur, were also connected with a drainage of the land, which was different in level from that now prevailing. The enormous volume of alluvial matter formed in the channels of the old rivers, the contorted strati- fication of some parts of such alluvium, and the large size of many of the transported stones which it contains, imply a climate which generated much snow and ice in winter, and «mean annual temperature lower than that now found in the same parts of Hurope.t The fossil shells also imbedded in the same deposits are all of species now living, and cha- tacteristic, with a few exceptions to be mentioned in the Sequel, of Central and Northern Europe. The Meee absence * See Mr. Boyd pee list of mam- f+ For contortions of the drift, see era of the Dordogne Sib aes Antiquity - Man, by the Author, p. 138. ™. of Sei. ae 1866, p. VOL. i N 178 CLIMATE OF THE MAMMOTH (Cu. X of the bones of reptiles, even of those of small dimensiong, ig very significant, as indicating a former state of the atmosphere and of the waters uncongenial to that class of vertebrata, Climate of the mammoth and its associates.— Geologists, when they first examined the fossils of the drift, approached the subject with the fullest conviction on their minds that the climate of the globe in the olden times was warmer than it is now. This opinion they had legitimately derived from the study of the Tertiary and Secondary rocks, and when they encountered the bones of the elephant, rhinoceros, hip- popotamus, lion, tiger, and hyena plentifully entombed in the old river-gravels above mentioned, and in the contemporaneous mud and breccia of caverns, they concluded, without hesita- tion, that as all the genera alluded to are now characteristic of warmer latitudes, their presence was in perfect harmony with the received doctrine. The fact that the numerous land and - freshwater shells accompanying the same fossils were almost without exception identical with those now inhabiting the same country, ought doubtless to have served as a warning against the belief in a hotter climate; but the well-known forms of many large and conspicuous mammatia made a greater impression on their minds than the diminutive mol- lusca, with which few were familiar. The late Dr. Fleming, however, before the notion had gained ground that a glacial epoch had intervened between tertiary and historical times, called in question, in 1829, the opinion that the bones of the elephant and rhinoceros, and other associated pachyderms and beasts of prey, implied a tropical climate. A near Te semblance, he observed, in form and osteological structure is not always followed in the existing mammiferous fauna by a similarity of geographical distribution ; and we must there- fore be on our guard against deciding too confidently, from mere analogy of anatomical structure, respecting the habits ‘The and physiological peculiarities of species now no more. zebra,’ he remarked, ‘delights to roam over the tropical plains ; while the horse can maintain its existence throughout an Iceland winter. The buffalo, like the zebra, prefers 4 high temperature, and cannot thrive even where the common ox prospers. The musk-ox, on the other hand, though nearly 7 v TS SS ATES. FAs Ga. X.] AND ITS ASSOCIATE 179 resembling the buffalo, prefers the stinted herbage of the arctic regions, and is able, by its periodical migrations, to outlive a northern winter. The jackal (Canis awreus) inhabits Africa, the warmer parts of Asia, and Greece; while the isatis, or arctic fox (Canis lagopus), resides in the arctic regions. The African hare and the polar hare have their geographical distribution expressed in their trivial names ; ’ * and different species of bears thrive in tropical, temperate, and arctic latitudes. Other writers soon followed up the same line of argument, and Mr. Hodgson among others, in his account of the mam- malia of Nepal, stated that the tiger was sometimes found at the very edge of perpetual snow in the Himalaya.+ Pen- nant had previously mentioned, that it had been seen among the snows of Mount Ararat in Armenia, and later authorities have placed it beyond all doubt that a species of tiger identi- cal with that of Bengal is common in the neighbourhood of Lake Aral, near Sussac, in the forty-fifth degree of North latitude. Humboldt remarks, that the part of Southern Asia now inhabited by this Indian species of tiger is separated from the Himalaya by two great chains of mountains, each _ covered with perpetual snow,—the chain of Kuenlun, lat. 35° N., and that of Mouztagh, lat. 42°.—so that it is im- possible that these animals should merely have made ex- cursions from India, so as to have penetrated in summer to the forty-eighth and fifty-third degrees of North latitude. They must remain all the winter north of the Mouztagh, or Celestial Mountains. The last tiger killed, in 1828, on the Lena, in lat. 523°, was in a climate colder than that of Peters- burg and Stockholm.+ A species of panther (Felis irbis), covered with long hair, has been discovered in Siberia, evidently inhabiting, like the tiger, a region north of the Celestial Mountains, which are In lat. 4.2°, In regard to the climate of the living elephant, the Rey. . Pleming, Ed. New Phil. Journ.,No. + Humboldt, Fragmens de Géologie rata 282, 1829. The zebra, however, &c., tome ii. p. 888. Ehrenberg, Ann. in a chiefly the extra-tropical parts des Sci. N at., tome xxi. pp. 387, 390. rica, § Ehrenberg, ibid. t Journ, of Asiat, Soe., vol. i. p, 240. N 2 180 CLIMATE OF THE MAMMOTH [Cu X Robert Everest observes, that the greatest elevation at which it is found in a wild state is inthe north-west Himalaya, at place called Nahun, about 4,000 feet above the level of the Sea, and in the 31st degree of N. lat., where the mean yearly tem- perature may be about 64° Fahrenheit, and the difference be- tween winter and summer very great, equal to about 36° F., the month of January averaging 45°, and June, the hottest month, 91° F.* More recently, Von Schrenck, writing in 1858, announced that in Amoorland, part of North-Eastern Asia, then recently annexed to the Russian Empire, no less than 34 out of 58 living quadrupeds are identical with European species. Among those which are not European, some are arctic, others of tropical forms ; in illustration of which, he states that the Bengal tiger, ranging sometimes northwards as far as lat. 42°, subsists chiefly on the flesh of the reindeer, while on the other hand, the small tailless hare or pika occasionally wan- ders from its polar haunts to parts of Amoorland as far south as 48°.+ In America, the jaguar has been seen wandering from Mexico as far north as Kentucky, lat. 37° N.{, and m the opposite direction as far as 42° 8. in South America,—a latitude which corresponds to that of the Pyrenees in the northern hemisphere.§ The range of the puma is still wider, for it roams from the equator to the Straits of Magellan, being often seen at Port Famine, in lat. 53° 38’ S. When the Cape of Good Hope was first colonised, the two-horned African rhinoceros was found in lat. 34° 29’ 8., accompanied by the elephant, hippopotamus, and hyena. Here the migration of all these species towards the south was arrested by the ocean; but if the African continent had been prolonged still farther, and the land had been of moderate elevation, it is highly probable that they might have extended their range to a greater distance from the tropics. Now, if the Indian tiger can range In our own times to the southern borders of Siberia, or skirt the snows of the Hima- laya, and if the puma can reach the fifty-third degree of * Everest on Climate of Foss. Eleph., + Rafinesque, Atlantie Journ., p- 18. Journ. of Asiat. Soc,, No. 25, p. 21. § Darwin's Journal of Travels 12 1 12, 1861. South America, &e., 1832 to 1836, m Voyage of H.M.S. Beagle, p. 159. r Nat. Hist. Rev., vol. i. p. Antiquity of Man, p. 168, } x3 AND ITS ASSOCIATES. 181 Jatitude in South America, we may easily understand how large species of the same genera may once have inhabited Northern Europe. The mammoth (H. primigenius), already alluded to, as occurring fossil in England, was decidedly dif- ferent from the two living species of elephants, one of which ‘; limited to Asia, south of the 31° of N. lat., the other to Africa, where it extends, as before stated, as far south as the Cape of Good Hope. The bones of the fossil species are very widely spread over Europe and North America; but are no- where in such profusion as in Siberia, particularly near the shores of the Frozen Ocean. But if we are thence to conclude that this animal preferred a northern climate, it will naturally be asked, by what food was it sustained, and why does it not still survive near the Arctic circle?* Pallas and other writers describe the bones of the mammoth as occurring ina very fresh state throughout all the Lowland of Siberia, stretching in a direction west and east, from the borders of Europe to the extreme point nearest America, from south to north, from lat. 60° and from the base of the mountains of Central Asia to the shores of the Arctic Sea. (See map, fig. 7.) Within this space, scarcely inferior in area to the whole of Europe, fossil ivory has been collected almost everywhere, onthe banks of the Irtish, Obi, Yenesei, Lena, and other rivers. The elephantine remains do not occur in the marshes, but where the banks of the rivers present lofty precipices of sand and clay; from which circumstance Pallas very justly inferred that, if sections could be obtained, similar bones might be found in all the elevated lands intervening between the great rivers. Strahlenberg, indeed, had stated, before the time of Pallas, that wherever any of the great rivers over- flowed and cut out fresh channels during floods, more fossil remains of the same kind were invariably disclosed. As to the position of the bones, Pallas found them in some * The speculations which follow,on companions, MM. de Verneuil and the ancient physical geography of Sibe- _ Keyserli iy ma, and its former fitness as a residence Geology of Russia, 1845 (vol.i. p. 497), =} = =) ae om @ a ge He ) eas = ° — ~_ i) =) NS l= fo) iS) 5B as ja O i} ° ct, soy oO B @ =r) 3 mn a ieje) [I < fo) =) 5 — =) oo 4 & ide =} oO SB ct a6 =] co =) = mn ie) am i) S =- cS Qu fer) ie} = 99 KB (a2) Qu their present form in my 4th edition, that their investigations have led them tne 1835, Sir R. Murchison and his to similar conclusions. 189 CLIMATE OF THE MAMMOTH (Ca. X, places imbedded together with marine remains; in others simply with fossil wood, or lignite, such as, he says, might Fig. 7. VELVHOSLW VY ae trom Greenwich MAP OF SIBERIA, the fossil bones of the mammoth abound. a PA Krasnojarek 0 Map showing the course of the Siberian rivers from south to north, from temperate to arctic regions, in the country where have been derived from carbonised peat. On the banks of the Yenesei, below the city of Krasnojarsk, in lat. 56°, he eo courtrty where aA moth abou from temperate to aretic regions, im th x mae Map showing the course of the Siberian rivers from south to north, - the fossil bones of the a CS =e SS BS. AD Cu. X-] AND ITS ASSOCIATES, 183 observed grinders and bones of elephants, in strata of yellow and red loam, alternating with coarse sand and gravel, in which was also much petrified wood of the willow and other trees. Neither here nor in the neighbouring country were there any marine shells, but merely layers of black coal.* But grinders of the mammoth were collected much farther down the same river, near the sea, in lat. 70°, mixed with marine petrifactions.t Many other places in Siberia are cited by Pallas, where sea shells and fishes’ teeth accom- pany the bones of the mammoth, rhinoceros, and Siberian buffalo, or bison (Bos priscus). Oarcasses of elephant and rhinoceros preserved in frozen mud.—But it is not on the Obi nor the Yenesei, but on the Lena, farther to the east, where, in the same parallels of latitude, the cold is far more intense, that fossil remains were first found in the most wonderful state of preservation. In 1772, Pallas obtained from Wiljuiskoi, in lat. 64°, from the banks of the Wiljui, a tributary of the Lena, the carcass of a rhinoceros (R. tichorhinus), taken from the sand in which it must have remained congealed for ages, the soil of that region being always frozen to within a slight depth of the surface. This carcass, which was compared to a natural mummy, emitted an odour like putrid flesh, part of the skin being still covered with short crisp wool and with black and grey hairs. In allusion to the quantity of hair on the foot and head conveyed to St. Petersburg, Pallas asked whether this animal might not have inhabited a cold region of Middle Asia, its clothing being so much warmer than‘that of the African rhinoceros. { Professor Brandt, of St. Petersburg, in a letter to Baron Alex. Von Humboldt, dated 1846, adds the following parti- culars respecting this wonderful fossil relic :—‘I have been so fortunate as to extract from cavities in the molar teeth of the Wiljui rhinoceros a small quantity of its half-chewed food, among which fragments of pine-leaves, one-half of the seed of a polygonaceous plant, and very minute portions of wood with porous cells (or small fragments of coniferous * Pa llas, Reise im Russ. Reiche, pp. + Nov. Com. Petrop., vol. xvii. p. 584. hdd 591. : t Ibid. p. 184 CLIMATE OF THE MAMMOTH [Cm Xx, wood), were still recognisable. It was also remarkable, on a close investigation of the head, that the blood-vessels digeo- vered in the interior of the mass appeared filled, even to the capillary vessels, with a brown mass (coagulated _ which in many places still showed the red colour of blood.’ Thirty years after the discovery of the rhinoceros by Pallas, the entire carcass of a mammoth was obtained in 1803, by Mr. Adams, much farther to the north. It fell from a mass of ice, in which it had been encased, on the banks of the Lena, in lat. 70°; and so perfectly had the soft parts of the carcass been preserved, that the flesh, as it lay, was devoured by wolves and bears. This skeleton is still in the museum of St. Petersburg, the head retaining its integument and many of the ligaments entire. The skin of the animal was covered, first, with black bristles, thicker than horse- hair, from twelve to sixteen inches in length; secondly, with hair of a reddish brown colour, about four inches long; and thirdly, with wool of the same colour as the hair, about an inch in length. Of the fur, upwards of thirty pounds’ weight were gathered from the wet sandbank. The individual was nine feet high and sixteen feet long, without reckoning the large curved tusks: a size rarely surpassed by the largest living male elephants.t It is evident, then, that the mammoth, instead of being naked, like the living Indian and African elephants, was enveloped in a thick shaggy covering of fur, probably as impenetrable to rain and cold as that of the eee The species may, as Cuvier observed,$ have been fitted by nature to withstand the vicissitudes of a northern climate; and itis certain that, from the moment when the carcasses, both of the rhinoceros and elephant, above described, were buried in Siberia, in latitudes 64° and 70° N., the soil must have remained frozen, and the atmosphere as ool’ as at this day. The discoveries made in 1843 by Mr. Middendorf, a distin- guished Russian naturalist, and which he communicated to me in September 1846, afford more precise information as to * Quart. Journ. Geol. Soe. Lond. , vol. t Fleming, Ed. New Phil. Journ., No. iv. p. 10, Memoirs. Bah a 285, 1829. ‘girs al du Nord, St. Petersburg, § Ossements fossils, 4th ed., 1836. x. X.] AND ITS ASSOCIATES. 185 the climate of the Siberian lowlands, at the period when the extinct quadrupeds were entombed. One elephant was found on the Tas, between the Obi and Yenesei, near the Arctic circle, about lat. 66° 30’ N., with some parts of the flesh in so perfect a state that the bulb of the eye is now. preserved in the Museum at Moscow. Another carcass, together with a young individual of the same species, was met with in the game year, 1843, in lat. 75° 15’ N., near the river Taimyr, with the flesh decayed. It was imbedded in strata of clay and gand, with erratic blocks, at about fifteen feet above the level of the sea. In the same deposit Mr. Middendorf observed the trunk of a larch-tree (Pinus larix), the same wood as that now carried down in abundance by the Taimyr to the Arctic Sea. There were also associated marine fossil shells of living north- ern species, and which are moreover characteristic of the drift or glacial deposits of Scotland and other parts of Europe. Among these, Nucula pygmea, Tellina calearea, Mya truncata, and Saxicava rugosa were conspicuous. So fresh is the ivory throughout Northern Russia, that, according to Tilesius, thousands of fossil tusks have been collected and used in turning; yet others are still procured and sold in great plenty. He declares his belief that the bones still left in Northern Russia must greatly exceed in number all the elephants now living on the globe. Remains of the mammoth have been collected from the cliffs of frozen mud and ice on the east side of Behring’s Straits, in Hschscholtz Bay, in Russian America, lat. 66° N. As the cliffs waste away by the thawing of the ice, tusks and bones fall out, and a strong odour of animal matter is exhaled from the mud.* Intelligence has been received at St. Petersburg (from an exploring expedition now in progress, 1866), that in the flat country near the mouths of the Yenesei, between lat. 70° and SN., many skeletons of mammoths, retaining the skin and hair, have been found. The heads of most of them are said to have been turned towards the south. The preservation of these and other individuals before mentioned in ice or frozen mud, is a fact which has a most important bearing on all * See Dr. Buckland’s description of these bones, Appen. to Beechy’s Voyage. 186 ‘CLIMATE OF THE MAMMOTH [Cr X, speculations concerning the climate of the Arctic regions, both at the time when these animals existed, and throughout the whole period which has since elapsed. There may have been oscillations of temperature, accompanying changes in the geography of the globe, or partly due to distinct phases of the precession of the equinoxes, or to various states of the ellipticity of the earth’s orbit since the era in question, but one thing is clear, that the ice or congealed mud in which the bodies of such quadrupeds were enveloped has never once been melted since the day when they perished, so as to allow the free percolation of water through the matrix, for had this been the case, the soft parts of the animals could not have remained undecomposed. Rome is the most southern limit to which the fossil bones of the mammoth have as yet been traced in Europe. Some were detected in 1858 in Monte Sacro, one of the Seven Hills of Rome, where they were recognised by M. Lartet among the mammalian remains obtained by Prof. Ponzi from the voleanic gravel of that locality. Other specimens, as I learn from M. de Verneuil, have since been found in ancient alluvium on the banks of the Tiber, at Ponte Molle, associated with flint implements of contemporaneous date. e are not obliged, says Dr. Falconer, to suppose that this ancient elephant, which in Europe extended its range from the Tiber to the Lena, and in North America from Eschscholtz Bay to the Gulf of Mexico, was enveloped in every latitude with a thick covering of fur. ‘The fine silky fleece with which the domestic goat is clothed on the plains of Tibet, where the winter, at a height of 16,000 feet above the sea, is most severe, disappears entirely from the Same animal in the valley of Cashmere.’ * Dr. Fleming, long before the discovery above alluded to by Brandt, of fossil pine-leaves in the molar of a Siberian rhinoceros, had hinted, that ‘the kind of food which the existing species of elephant prefers will not enable us to determine, or even to offer a probable conjecture, concerning that of the extinct species. No one,’ he said, ‘acquainted * Falconer, American Fossil Elephant, Nat. Hist. Rev., vol. iii. 1863. Cu. X.] AND ITS ASSOCIATES. 187 with the gramineous character of the food of our ee stag, or roe, would have assigned a lichen to the reindeer. Travellers mention that, even now, when the climate of Fastern Asia is so much colder than the same parallels of latitude farther west, there are woods not only of fir, but of birch, poplar, and alder, on the banks of the Lena, as far north as latitude 60°.* Professor Owen observes, that the teeth of the mammoth differ from those of the living elephants, whether Asiatic or African, having a larger proportion of dense enamel, which may have enabled it to subsist on the coarser igneous tissues of trees and shrubs. In short, he is of opinion, that the structure of its teeth, as well as the nature of its epidermis and coverings, may have made it ‘a meet companion for the reindeer.’ It has been suggested, that as, in our own times, the northern animals migrate, so the Siberian elephant and rhinoceros may have wandered towards the north in summer. The musk-oxen annually desert their winter quarters in the south, and cross the sea upon the ice, to graze for four months, from May to September, on the rich pasturage of Melville Island, in lat. 75°. The mammoth may in like man- ner have made excursions, during the warmth of a northern summer, from the central or temperate parts of Asia to the 75th parallel of latitude, even though the continuous land may not have extended so far. If such were the case, the preservation of their bones, or even occasionally of their entire carcasses, in ice or frozen soil, may be accounted for, without resorting to speculations concerning sudden revolutions in the former state and climate of the earth’s surface. We seem entitled to assume, that, in the time of the extinct elephant and rhinoceros, the Lowland of Siberia stretched less far towards the north than now ; for we have seen (p. 183) that the strata of this Lowland, in which the fossil bones lie buried, were originally deposited beneath the sea; and we know, from the facts brought to light in Wrangel’s Voyage, in the years 1821, 1822, and * History of British Fossil Mammalia, 1844, p. 261 e¢ seq. 188 CLIMATE OF THE MAMMOTH "On, X. 1823, that a slow upheaval of the land along the borders of the Icy Sea is now constantly taking place, similar to that experienced in part of Sweden. In the same manner, then, as additions have been made to the shores of the Gulf of Bothnia, not only by the influx of sediment brought down by rivers, but also by the elevation and consequent drying up of the bed of the sea, so a like combination of causes may, in modern times, have been extending the low tract of land where marine shells and fossil bones occur in Siberia.* Such a change in the physical geography of that region, implying a constant augmentation in the quantity of arctic land, would, according to principles to be explained in the twelfth chapter, tend to increase the severity of the winters, and, by limiting the supply of food, finally contribute to the extermination of the mammoth and its contemporaries. On referring to the map (p. 182), the reader will see how all the great rivers of Siberia flow at present from south to north, from temperate to arctic regions, and they are all liable, like the Mackenzie, in North America, to remarkable floods, in consequence of flowing in this direction. For they are filled with running water in their upper or southern course when still frozen over for several hundred miles near their mouths, where they remain blocked up by ice for six months in every year. The descending waters, therefore, finding no open channel, rush over the ice, often changing their direction, and sweeping along forests and prodigious quantities of soil and gravel mixed with ice. Now the rivers of Siberia are among the largest in the world, the Yenesei having a course of 2,500, the Lena of 2,000 miles; so that we may easily conceive that the bodies of animals which fall into their waters may be transported to vast distances towards the Arctic Sea, and, before arriving there, may be stranded upon and often frozen into thick ice. Afterwards, when the ice breaks up, they may be floated still farther towards the * Since the above passage was first by M. Middendorf (see above, p. 185), printed in a former iim ae 1835, that the Lowland of Siberia has actually it has been shown by tl of been extended since the existing spectes Sir R. Murchison, M. ae cents ane of shells inhabited the northern seas. Count Keyserling, and more recently Cu. X.] AND ITS ASSOCIATES. 189 ocean, until at length they become buried in fluviatile and submarine deposits near the mouths of rivers. Humboldt remarks, that near the mouths of the Lena a considerable thickness of frozen soil may be found at all seasons at the depth of a few feet; so that if a carcass be once imbedded in mud and ice in such a region and in such a climate, its putrefaction may be arrested for indefinite ages.* According to Prof. Von Baer of St. Petersburg, the ground ‘s now frozen permanently to the depth of 400 feet at the town of Yakutzk, on the western bank of the Lena, in lat. 62° N., 600 miles distant from the Polar Sea. Mr. Hedenstrom tells us that, throughout a wide area in Siberia, the boundary cliffs of the lakes and rivers consist of alternate layers of earthy materials and ice, in horizontal stratification ;+ and Mr. Middendorf told me in 1846, that, in his tour there three years before, he had bored in Siberia to the depth of seventy feet, and, after passing through much frozen soil mixed with ice, had come down upon a solid mass of pure transparent ice, the thickness of which, after penetrating two or three yards, they did not ascertain. The late Sir John Richardson informed me, that in the northern parts of America, comprising regions now inhabited by many herbivorous quadrupeds, the drift snow is often con- verted into permanent glaciers. It is commonly blown over the edges of steep cliffs, so as to form an inclined talus hun- dreds of feet high ; and when a thaw commences, torrents rush from the land, and throw down from the top of the cliff allu- . vial soil and gravel. This new soil soon becomes covered with vegetation, and protects the foundation of snow from the rays of the sun. Water occasionally penetrates into the crevices and pores of the snow; but, as it soon freezes, it serves the more effectively to consolidate the mass into compact ice. It may sometimes happen that cattle erazing in a valley at the base of such cliffs, on the borders of a sea or river, may be overwhelmed by drift snow, and at length enclosed in solid ice, and then transported towards the polar regions. Or a * Humboldt, Fragmens Asiatiques, ternaire, who cites Observ. sur la Si- tom. ii. p. 393. périe, Bibl. Univ., Juillet 1832. + Reboul, Géol. de la Période Qua- 190 CLIMATE OF THE MAMMOTH [Cu. X, herd of mammoths, returning from their summer pastures jn the north, may have been surprised, while crossing a stream, by the sudden congelation of the waters. The missionary Hue relates, in his Travels in Tibet in 1846, that, after many of his party had been frozen to death, the survivors pitched their tents on the banks of the Mouroui-Ousson (which lower down becomes the famous Blue River), and saw from their encampment ‘some black shapeless objects ranged in file across the stream. As they advanced nearer, no change either in form or distinctness was apparent; nor was it till they were quite close, that they recognised in them a troop of the wild oxen, called Yak by the Tibetans.* There were more than fifty of them encrusted in the ice. No doubt they had tried to swim across at the moment of congelation, and had been unable to disengage themselves. Their beautiful heads, surmounted by huge horns, were still above the surface, but their bodies were held fast in the ice, which was so trans- parent that the position of the imprudent beasts was easily distinguishable ; they looked as if still swimming, but the eagles and ravens had pecked out their eyes.’+ Considering all the facts above enumerated, it seems reasonable to imagine that a large region in Central Asia including, perhaps, the southern half of Siberia, enjoyed, at no very remote period in the earth’s history, a climate sufficiently mild to afford food for numerous herds of ele- phants and rhinoceroses, of species distinct from those now living. It has often been taken for granted that herbivorous animals, of large size, require a very luxuriant vegetation for their support ; but this opinion is, according to Mr. Darwin, completely erroneous :—‘ It has been derived,’ he says, ‘from our acquaintance with India and the Indian islands, where the mind has been accustomed to associate troops of elephants with noble forests and impenetrable jungles. But the southern parts of Africa, from the tropic of Capricorn to the Cape of Good Hope, although sterile and desert, are re- markable for the number and great bulk of their indigenous * Conjectured to be the wild stock of Tartary, Tibet, and China (ch. xv. p- Bos grunniens. 234), by M. Hue. Longman, 1882. Yt Recollections of a Journey through ca. XJ AND ITS ASSOCIATES. 191 quadrupeds. We there meet with an elephant, five species of rhinoceros, a hippopotamus, a giraffe, the bos caffer, the elan, two zebras, the quagga, two gnus, and several antelopes. Nor must we suppose that, while the species are numerous, the individuals of each kind are few. Dr. Andrew Smith gaw, in one day’s march, in lat. 24° 8., without wandering to any ereat distance on either side, about 150 rhinoceroses, with several herds of giraffes, and his party had killed, on the previous right, eight hippopotamuses. Yet the country which they inhabited was thinly covered with grass and bushes about four feet high, and still more thinly with mi- mosa-trees, so that the waggons of the travellers were not prevented from proceeding in a nearly direct line.’ * In order to explain how so many animals can find support in this region, it is suggested that the underwood, of which their food chiefly consists, may contain much nutriment in a small bulk, and also that the vegetation has a rapid growth; for no sooner is a part consumed, than its place, says Dr. Smith, is supplied by a fresh stock. Nevertheless, after making every allowance for this successive production and consumption, it is clear, from the facts above cited, that the quantity of food required by the larger herbivora is much less than we have usually imagined. Mr. Darwin conceives that the amount of vegetation supported at any one time by Great Britain may exceed, in a tenfold ratio, the quantity existing on an equal area in the interior parts of Southern Africa. It is remarked, moreover, in illustration of the small con- nection discoverable between abundance of food and the magnitude of indigenous mammalia, that while in the desert part of Southern Africa there are so many huge animals, there is not, in Brazil, where the splendour and exuberance ofthe vegetation are unrivalled, a single wild quadruped of the largest size. It would doubtless be impossible for herds of mammoths and rhinoceroses to subsist, at present, throughout the year, éven in the southern part of Siberia, covered as it is with snow during winter; but there is no difficulty in supposing a “ Darwin, Journal of Travels inS. of H.M.S, Beagle, p. 98. 2nd ed., Lon- America, é&¢., 1832-1836, in Voyage don, 1845, p. 86. 192 CLIMATE OF EUROPEAN DRIFT [Cu X. vegetation capable of nourishing these great quadrupeds to have once flourished between the latitudes 40° and 65° N. Climate of European Drift and Cave Deposits.—We may now ask, with what Huropean deposits does the frozen mud of Siberia containing the remains of the mammoth in go fresh a state correspond geologically? Their superficial dis- tribution, and the species of mammalia, as well as the fact that the shells which Middendorf and others observed in them are of living species, seem to connect them chronologi- cally with that paleolithic drift in which flint implements have been detected in England, France, and Italy. The temperature which prevailed in the valleys of the Thames, Somme, and Seine at the era in question, was, according to Mr. Prestwich, 20° Fahrenheit colder than now, or such as would now belong to a country from 10° to 15° of latitude more to the north.* This estimate is founded on a careful analysis of the land and freshwater shells which accompany the remains of the mammoth and its associates in the paleolithic alluvium. If we confine our attention to those terrestrial shells which are most commonly buried in the same gravel and sand as the Hlephas primigenius and Rhino- ceros tichorhinus, we find them to amount to no less than 48 species in the valley of the Thames and its neighbourhood. All but two of these still survive in Britain; these two, Helix incarnata and Helix ruderata, still inhabit the continent of HKurope, and have a great range from north to south. The associated freshwater shells, more than twenty in number, are also British species; but as they occur, with two or three exceptions, as far north as Finland, their presence is not opposed to the hypothesis of a cold climate, especially as the Limnee are capable of being frozen up, and then reviving again when the river-ice melts. At Fisherton, near Salisbury, one of the rude flint implements of the earliest stone age was found in drift containing the mammoth and Siberian rhinoceros, together with the Greenland lemming and a Spermophilus, a northern form of quadruped allied to the marmot, besides the tiger, hyena, horse, and other extinct and living species-; the whole assemblage being * Prestwich, P es ul. Trans., 1864, part 2, p. 89. e confirmatory Ot Cu. X.] AND CAVE DEPOSITS. 193 the opinion, that the men of the early stone period had often ¢o contend with a climate more severe than that now pre- vailing in the same parts of Hurope.* The late Edward Forbes compared the condition of Britain and the neighbour- ing parts of the continent, during the period next preceding the historical, to the ‘barren grounds’ of Boreal America, including the Canadas, Labrador, Rupert’s Land, and the countries northwards where the reindeer, musk ox, wolf, arctic fox, and white bear now live.t But we find in some parts of the drift evidence of a conflicting character, such as may suggest the idea of the occasional intercalation of more genial seasons of sufficient duration to allow of the migration and temporary settlement of species coming from another and more southern province of mammalia, so that their remains were buried in river gravels at the same level as the bones of animals and shells of a more northern climate. If we allow a vast lapse of ages for the accumulation of the drift, we may take for granted that there must have been such changes in climate, owing sometimes to geographical and sometimes to astronomical causes, which will be treated ot in the twelfth chapter. Bones of the hippopotamus, of a species closely allied to that now inhabiting the Nile, are often accompanied in the valley of the Thames and else- where by a species of bivalve shell, Cyrena fluminalis, now living in the Nile and ranging through a great part of Asia as far as Tibet, but quite extinct in the rivers of Europe. Imbedded in the same alluvium with this shell, we find at Grays in Essex, Unio littoralis, a mussel no longer British, but abounding in France in rivers more southern than the Thames. The Hydrobia marginata is also a shell sometimes met with in the drift, a species now inhabiting more southern latitudes in Europe. The kind of elephant and rhinoceros accompanying the Cyrena at Grays (H. antiquus and R. me- jarhinus) are not the same as the mammoth and rhinoceros which occur with their flesh in the ice and frozen mud of Siberia, or in those assemblages of mammalia which have * Ant. of Man, 3rd edit., Appendix, Forbes, in the Memoirssef Geol. Sur- a. vey of Great Brit., vol. i. p. 386. 1846. t See an admirable essay by E. i VOL. I 194 GLACIAL EPOCH. (Cu, X an arctic character in the drift of England, France, and Germany.* Some zoologists conjecture that the fossil species of hippopotamus was fitted for a cold climate, but it seems more probable that when the temperature of the river water was congenial to the Cyrena above mentioned, it was also suited to the hippopotamus. Glacial Epoch.—The next step of our retrospect carries us back to what has been called the Glacial Epoch, which, though for the most part anterior to the valley-drifts and cave deposits of the paleolithic age above mentioned, was still so closely connected with that period that we cannot easily draw a line of demarcation between them. The disper- sion of large angular fragments of rock, called erratics, over the northern parts of Europe and North America, far from the nearest parent rocks from which they could have been derived, had long presented a difficult enigma to geologists before it began to be suspected that they might have been transported by ice, and at a period when large parts of the present continents were submerged beneath the sea. These blocks are observed to extend in Europe as far south as lat. 50°, and still farther in America, or to lat. 40°. It was remarked that some of them were polished, and striated on one or more of their sides in a manner strictly analogous to stones imbedded in the terminal moraines of existing glaciers in the Alps. In many areas covered with them both in America and Europe, the underlying solid rocks were seen: to be marked by similar scratches and rectilinear furrows, their direction usually coinciding with the course which the erratics themselves had taken. As both the smoothing and striation of the transported fragments and the surfaces of the rocks in situ were identical in character with effects recently produced by existing glaciers, it was at length ad- mitted, but not till after the point had been controverted for a quarter of a century, and in direct opposition to the opinion of the earlier geologists, that the climate which preceded the historical was not only colder as far south as lat. 50° in * The jawbone of a monkey (Ma- now considered as of very doubtful cacus pliocenus, Owen), which Iformerly authenticity. cited as belorging to the Essex drift, is on. X.] INTER-GLACIAL PERIODS. 195 Europe, and even to 46° in the Alps, but was marked by such intensity of cold, and such an accumulation of ice, as to be quite without parallel in corresponding latitudes in the present state of the globe, whether in the northern or southern hemisphere. Some marine shells of living arctic species, and which no longer frequent the seas of temperate latitudes, have been found in some parts of the glacial drift of Scotland and North America; so that evidence derived from the organic as well as from the inorganic world conspired to establish the former prevalence of a climate now proper to polar latitudes through- out a great part of Hurope. By aid of such marine drifts, great oscillations in the level of the land since the commencement of the Glacial Epoch were proved to have taken place. The change of level in Scotland, as demonstrated by this kind of proof, amounts to 500 feet, in some parts of central England to 1,200, and in North Wales to 1,400 feet; these movements having all occurred in post- tertiary times, or within the period of the living testacea. But Professor Ramsay infers, from the position of the stratified drifts of the Glacial Period in North Wales, that the full extent of the vertical movement which brought about first the submergence and then the re-emergence of the land ex- ceeded 2,000 feet. Inier-glacial Periods.— Without entering in this place into the proofs of two continental periods in Britain during the Glacial Epoch, separated from each other by a long interval of submergence, during which Great Britain and Ireland were in the state of an archipelago of small islands, it may be aifirmed that the excessive cold lasted for a long series of ages, although not always with the same intensity. As illus- trative of the fact of the cold having been intermitted or sometimes mitigated for a season, may be mentioned what the late Hugh Miller called ‘ striated pavements.’ These consist of horizontal surfaces of boulder clay, in which the imbedded boulders are seen to have been: subjected to a pro- Cess of abrasion similar to that which the solid rock below had previously undergone. In such instances large stones or blocks fixed in the clay have not only their original and 0 2 196 INTER-GLACIAL PERIODS. [Cu. x, independent striz, but have subsequently suffered a new gtri- ation which is parallel and persistent across them all. These appearances have been observed on the shores of the Firth of Forth, below Edinburgh, and in other places, both on the east and west coasts of Scotland, and on the shores of the Solway in England. Some examples of this second strig- tion may have been due to the friction of icebergs on the bed of the sea during a period of submergence; others to a second advance of land glaciers over moraines of older date.* . M. Morlot and others have adduced abundant evidence of two glacial periods in the Alps, during the first of which the glaciers attained colossal dimensions, fillg the great valley of Switzerland with ice, which reached from the Alps to the Jura, while on the southern side of the great chain other contemporaneous glaciers invaded the plains of the Po, where they have left moraines of truly gigantic dimensions. After these huge glaciers had retreated for a time, they advanced again, but on a smaller scale, though still vastly exceeding in size the largest Swiss glaciers of our day. The interval of milder weather, marked by the decrease of snow and ice in the Alps, has been called by Prof. Heer the Inter-glacial Period, which must have been of considerable duration, for it gave time for the accumulation of dense beds of lignite, like those at Durnten and other localities near Ziirich. During this intercalated series of warmer seasons the climate is supposed by Heer to have closely resembled that now experienced in Switzerland. He infers this from the fossil flora of the lignite, especially from the cones of the Scotch and spruce firs, and the leaves of the ash and yew, all of living species, as well as from the seeds of certain marsh plants. The insects also, and the freshwater shells, tell the same tale. Among the mammalia occurring in the same carbonaceous shales are an elephant (HE. antiquus), an extinct species of bear (Ursus spelcus), and a rhinoceros different from R. tichorhinus. That the forma- tion of the shale and lignite containing the above-mentioned remains was preceded and followed by periods of greater cold, is shown by the polished and striated rock surfaces on * A, Geikie, Phenomena of Glacial Messrs. C. Maclaren, Hugh Miller, Drift of Scotland, p. 66, who cites Milne-Heme, and Smith of Jordan-bill. CH. X] INTER-GLACIAL PERIODS, 197 ‘aikch the lignite rests, and by the large size of the erratic plocks which are superimposed upon the lignite.* In England the lignite, or forest bed as it is called, of Cromer, on the Norfolk coast, presents a singular analogy to that of Diirnten above described. It contains in like manner the cones of the spruce and the Scotch fir, and the seeds and leaves of marsh plants, and some shells and mammalia in common with the Swiss deposit. It was also preceded and followed by a period of greater cold. The antecedence of a colder climate is proved by the arctic character of a large proportion of the shells of living species included in the marine strata of Chillesford, near Ipswich, in lat. 52° N., which, according to the observations of Messrs. Prestwich and Searles Wood, are more ancient than the forest or lignite bed, and the fact is also confirmed by the marine shells of like character and age found ina deposit at Bridlington, in Yorkshire, lat. 54° N. On the other hand, proofs that the forest bed of Cromer was followed by an era of severe cold, is shown by the fact that it underlies the great mass of glacial drift, in part unstratified, and containing boulders and angular blocks transported from great distances, and some of them exhibiting polished and striated surfaces.+ We are by no means sufficiently advanced in our interpre- tation of the monuments of the Glacial Epoch, and of the long succession of events which mark its history, to be able toatfirm that the inter-glacial periods of Diirnten and Cromer, above mentioned, were contemporaneous ; but they both of them alike demonstrate that there were oscillations of tempe- rature in the course of that long epoch of cold. There were also great changes, as before stated, in the form of the earth’s crust, many movements of upheaval and subsidence, and many Conversions of sea into land, and land into sea, during the Glacial Epoch. We are in danger of underrating the quantity of time during which the cold prevailed ; because, in propor- tion as the ice increases in thickness, it cancels all marks of antecedent glaciation. The grinding action ef the great 1ce-sheet which now envelopes Greenland illustrates this Process. Were that ice to melt, it would require as much ‘ Antiquity of Man, pp. 212-218. { Heer, Urwelt der Schweiz, p. 532. 198 INTER-GLACIAL PERIODS. [Cu. X. skill to detect the evidence of the moraines and erratics of an older time as in the case of a palimpsest to recover the work of the original author, which had been purposely washed out to make room for the new manuscript. From the foregoing observations, the reader will learn that the prevalence of a colder climate at the close of the Tertiary, and in the early part of the Post-tertiary periods, has been derived from two perfectly independent sources of evidence; the first of which may be called inorganic, such as erratic blocks, moraines, and the polishing and striation of rocks ; and second, the organic, such as the arctic character of the shells found in the drift of temperate regions. But another or third proof was also pointed out by the late Edward Forbes, as derivable from the present geographical distribution of animals and plants in mountainous regions, especially in high latitudes, in Europe and North America. After the refrigeration of the northern hemisphere had lasted for thousands of years, an arctic fauna and flora must have inhabited the lower. lands of temperate latitudes, at a time when the more elevated parts of the same country were buried under permanent snow and ice. On the return of a warmer climate, when the excess of snow was gradually reduced, the arctic species of plants, insects, birds, and mam- malia, would ascend to the higher parts of each continent, while the plains would be invaded by species migrating from the south. Hence an arctic fauna and flora, which once extended from polar latitudes far to the south, ranging con- tinuously over what are now the temperate regions of America, Europe, and Asia, became restricted to the summits of the highest chains, such as the Alps or the mountains of Scotland, Scandinavia, and New Hampshire in the United States. The identity of the species now found in isolated patches at or near the tops of so many widely separated mountains would have been inexplicable, had not the geolo- gist discovered that about the close of the Tertiary era there was a glacial epoch instead of that high temperature formerly assigned to times preceding the historical.* British Pliocene strata, showing transition from warmer to * Edward Forbes’ Memoirs of Geol. Survey, vol. i. p. 399. 1846. . Cu. X-] TRANSITION FROM WARMER TO COLDER CLIMATES. 199 solder climate.—When we pass beyond the ages when a colder temperature prevailed, and, receding a step farther into the past, examine the fossils of the British Pliocene strata, We find in the earliest or lowest members of them very interesting proofs of a climate warmer than that now prevailing in England, and more resembling that of the Mediterranean. As we ascend in the series, the shells of successive groups of strata, provincially called crag in Nor- folk and Suffolk, are seen to consist less and less of southern species, while the number of northern forms is always aug- menting, until in the uppermost or newest groups, in which almost all the shells are of living species, the fauna is very arctic in character, and that even in the 52nd and 54th degrees of North latitude, as before mentioned, p. 197.* Pliocene strata of Italy—The Pliocene strata of Italy, commonly called sub-Apennine, point in like manner to a warm climate. Such, for example, of the fossil shells of Sienna, Parma, and Asti, as are of species now inhabiting the Mediterranean and the Indian Ocean, correspond in size with individuals taken from the warmer of the two seas, those now surviving in the Mediterranean appearing to be stunted in their growth, as if deprived of the favourable conditions which the Pliocene Period afforded them in Italy.t It may also be observed, that the extinct species of the sub-Apen- nine fauna belong, in great part, to forms which are now most largely developed in equinoctial regions, as, for example, the genera Cancellaria, Cassidaria, Pleurotoma, and Cypreea. Warm climate of Upper Miocene Period.—The next step in our retrospective survey carries us to the monuments of the Upper Miocene Period. In the marine formations of this era a third or more of the testacea belong to living species, and these are usually at present inhabitants of more southern latitudes, and associated also with many genera now charac- teristic of warmer regions. Although in Great Britain strata of this period are entirely wanting, they occur in Belgium and North Germany, where they contain shells of the genera * Elements of Geol., pp. 198, 204. Bonelli of Turin, pointed out to me, in 8 Edit. of 1865. 1828, many examples in confirmation of t Professors Guidotti of Parma, and this point. 200 WARM CLIMATE OF UPPER MIOCENE PERIOD. [Cu e: Conus, Cancellaria, and Oliva—forms all of them foreign to our seas as well as to our British Pliocene deposits, and proper to and indicative of a higher temperature. The French strata of the same age, called the Falung of the Loire, point to similar inferences, and, like the contem- poraneous beds of the Vienna basin, contain some fossil shells of species now living in Senegal or off the western coast of Africa. The Upper Miocene flora and fauna of the whole of Central Europe afford unmistakable evidence of a climate approaching that now only experienced in sub-tropical re- gions. In one of the newest deposits of this Upper Miocene formation, Professor Heer has detected, at Cininghen, in Switzerland, the leaves, fruits, and sometimes flowers, of about 500 species of plants, in which we find a near re- semblance to the flora of the Carolinas and other Southern States of the American Union. After selecting 488 of these species as capable of comparison, specifically or generically, with plants now living, he finds that 131 are such as might be referred to the temperate zone, 266 to a sub-tropical, and 85 to a tropical latitude. In the present state of the globe, the island of Madeira presents the nearest approach to such a flora. The proportion of arborescent as compared to the her- baceous plants is very great, and among the former the pre- dominance of evergreens implies an absence of severe winter cold. A rich insect fauna, such as belongs to a warm climate, is also attested by the great number of the species of those genera which are most easily preservable in a fossil state. The reptiles which play so insignificant a part in the Pliocene fauna of Central and Northern Europe form a more con- spicuous feature in these Miocene formations. At (ininghen there are two tortoises and three species of salamanders, one of them more gigantic in size than the living species of Japan. Bones of the monkey tribe are also met with in Mio- cene strata near the foot of the Pyrenees in France. Among them is a gibbon, or long-armed ape, equal to man in stature, and the femur of a large species of this family has been de- tected by Dr. Kaup in strata of the same age at Eppelsheim, near Darmstadt, in a latitude which corresponds to the tates Cu. X.] FOSSILS OF THE SIWALIK HILLS. 901 southern part of Cornwall.* In Greece also, near Athens, the remains of Upper Miocene quadrumana have been met with, confirming the inferences as to the warm temperature of Europe previously drawn by naturalists from the fossils, shells, and corals of Touraine, Bordeaux, and Vienna. Fossils of the Siwdlik Hills—lt is a matter of no small interest to have learnt that when the climate of Europe was sub-tropical, a still greater heat prevailed nearer the equator. Our best information on this subject is afforded by the investigations of Dr. Falconer and Sir Proby Cautley, who collected, in 1837, a large number of fossil remains from the Giwalik Hills, which skirt the southern base of the Himalaya to the west of the river Jumna. Here the abundance and variety of the fossil mammalia is prodigious, there being no less than seven species of proboscidians of the genera ma- stodon and elephant. With these a huge extinct four-horned ruminant, called Sivatherium, was found, as well as a camel, a hippopotamus, a hyena, and more than one species of mon- key. The associated reptiles also bear witness to a tem- perature higher than that of any Huropean strata of the same date, for, besides some extinct saurians larger than any now existing, we find among them the living crocodile of the Ganges, OC. biporcatus, and the living gavial of the same river, besides a colossal extinct tortoise, of which the shell was no less than eight feet in diameter. Upper Miocene strata of the West Indies.—lf again we turn to the Upper Miocene formations of the West Indies, those, for example, of Antigua, San Domingo, and Jamaica, we discover in them species of corals similar to those found in beds of the same age at Vienna, Bordeaux, and Turin, and some of which, as Dr. Duncan has shown, have a near affinity to species now living in the South Sea, Indian Ocean, and Red Sea. They lead irresistibly to the opinion that there was a much greater analogy in those ages than thereis now between the temperature of the West Indies in lat. 18° and that of Europe in lat. 48°.+ Of Iceland.—If we then pass from the equatorial to ; Ke Owen, Geol. Trans., 1862, and Geo- + Duncan, West Indian Corals, Quart. ogist, 1862, p. 247. eol. Journ., p. 455, vol. xix. 186 202 LOWER MIOCENE STRATA. [Cu X, the arctic latitudes of the northern hemisphere, we find in certain beds of lignite or surturbrand in Iceland, recently examined by Professor Heer, an assemblage of fossil plants resembling in many respects that of (ininghen, before men- tioned, which, though not of so sub-tropical a character, ex- ceeded as much the warmth now enjoyed in Iceland as did the temperature of the Upper Miocene flora of Central Europe surpass that of the vegetation now proper to the same region.* Lower Miocene strata.—By referring to our table at p. 139, the reader will see that the Lower Miocene strata come next in order as we recede from the more modern formations to those of higher antiquity. They contain scarcely any living species of shells or plants, yet so many of their fossil remains are common to them and the Upper Miocene formation, that this fact alone would lead us to expect that they would afford indications of a warm climate. Such an anticipation is more than confirmed, both by negative and positive evidence ; for, in the first place, nearly all the genera of plants which in the Gininghen beds were mentioned as characteristic of tem- perate latitudes, are wanting in the Lower Miocene, while the tropical forms are more numerous. Among these last are palms of the genus Pheenicites, closely allied to the date- palm. About 80 other plants are enumerated by Heer, all of which would be cut off by such a winter as now prevails in Central and Southern Europe. Ligneous plants constitute two-thirds of the flora, and the preponderance of evergreens exceeds even that observed in the Upper Miocene strata of (ininghen. There are also more reptiles in these older beds, and some of considerable size. Among them are no less than three crocodiles and fifteen land and freshwater tor- toises.t ‘The Lower Miocene flora has been traced from Italy northwards to Devonshire, and even to Iceland. In these high latitudes, however, the tropical and sub-tropical genera disappear, though the vine and tulip-tree and some other forms indicate a temperature 15° or 20° Fahr. warmer than that now belonging to the same countries. * Heer and Gaudin, Climat du Pays { Heer and Gaudin, Climat du Pays Tertiaire, p. 178. Y Heer, Urwelt der Schweiz, p. 401. Tertiaire, pp. 174, 2 CX] MIOCENE FOSSIL TREES IN ARCTIC LATITUDES. 203 Miocene fossil trees growing in high Arctic latitudes.—The extent to which the Miocene flora flourished within the Arctic circle, even as far towards the pole as our exploring expeditions have penetrated, has been clearly pointed out by Professor Heer, in an important treatise on the fossil flora of the Arctic regions now ready for publication.* In the numerous plates which illustrate this work, we see figures of more than 60 species of North Greenland fossil plants, found opposite Disco Island, lat. 70° N. Among them are several species of Sequoia (Wellingtonia), with their male catkins and cones, agreeing specifically with Lower Miocene plants of Swit- verland, Germany, or England. There are also seven other coniferee, four poplars, two willows, three species of beech, four of oak (some of which have leaves half a foot long), a plane-tree, a walnut, a plum or prunus, a buckthorn, an andromeda, a daphnogene with large leathery leaves, and seve- yal other evergreens, some of new and extinct genera. The large-leaved trees imply, according to Heer, a high summer temperature, while the evergreens exclude the idea of a very cold winter. That these and other fossil plants from arctic localities really lived on the spot, and were not drifted thither by marine currents, is proved by the quantity of leaves pressed together, and in some cases associated with fruits, also by the marsh plants which accompany them, and by the upright trees with roots which were seen by Capt. Inglefield and by Rink. Still farther north in Spitzbergen, in lat. 78° 56’ N., no less then 95 species of plants are described by Heer, many of them agreeing specifically with N orth Greenland fossils. In this flora we observe Taxodium of two species, a hazel, poplar, alder, beech, plane-tree, lime (Tilia), and a potomo- geton, which last indicates a freshwater formation, accumu- lated on the spot. Such a vigorous growth of fossil trees, in a country within 12° of the pole, where there are now scarcely any shrubs except a dwarf willow and a few herbaceous and eryptogamous plants, most of the surface being covered with snow and ice, is truly remarkable. When the fossils are * Heer, Flora Fossilis Arctica, with denskiold, and Captain Sir L. McClin- 40 illustrative plates, containing figures tock, Sir R. Maclure, Colomb, Ingle- of fossil plants, collected by M. Nor- _ field, and others. 204 MIOCENE FOSSIL TREES IN ARCTIC LATITUDES. (Crax: compared with the miocene species of Central Hurope and Italy, many of them are found to be the same, and it ig clear that the climate was not only much warmer than now, but the temperature of Europe and the Arctic circle was much less contrasted; nevertheless, the flora of Spitzbergen was by no means so sub-tropical at the era alluded to as was that of Switzerland, Germany, and Devonshire, for in the Lower Miocene period, the difference of latitude made itself felt ag now, although in a less degree. Protessor Heer infers, with great probability, that pines, alders, poplars, willows, and other hardy genera reached the pole itself in Miocene times, if there was land there, because they range at present from 4to 10 degrees farther north than the Taxodium, Beech, Plane and Lime, which accompany them ina fossil state in the same formation at Spitzbergen. Some of the last-mentioned genera are in a higher latitude in Spitzbergen, by 8, 17, and 23 degrees, than the living representatives of the same genera. We cannot hesitate, therefore, to conclude that in Miocene times, when this vegetation flourished in Spitzbergen, North Greenland, and on the Mackenzie river, as well as Banks Land, and other circumpolar countries, there was no snow in the arctic regions, except on the summit of high moun- tains, and even there perhaps not lasting throughout the year. If it be asked whether in the entire Miocene series there are no indications of intercalated spells of colder climate like the glacial episode before mentioned, as intervening between he older Pliocene and the modern eras, I may reply that there are none which can at present be established on organic evidence; I will therefore defer till the close of this chapter some apparent signs of ice-action which have been detected in miocene strata near Turin, and proceed at once to carry back our retrospective survey to the next antecedent or Hocene period. Hocene fauna and flora.—In the flora of the upper mem- bers of this great series, we find in the neighbourhood of Paris and in the Isle of Wight, some plants which, like the palmetto, attest a warmer temperature. Among the accom- panying reptiles, there are many crocodiles and tortoises, lhe J “Ekete Cu. X-] SIGNS OF ICE-ACTION IN TERTIARY TIMES. 205 such as we now only meet with in more southern regions.* In the middle eocene, as in the caleaire grossier, for example, near Paris, the marine testaceous fauna is richer and more yaried than that now proper to seas so far north. The flora of the same division of the Tertiary period, as, for example, that of Alum Bay in the Isle of Wight, of Monte Bolea in the North of Italy, or that of Aix en Provence in the South of » France, comprises species and genera having a great affinity to Lower Miocene forms, but departing farther than do these from the modern European type, and, according to Heer, resembling in many respects plants of the tropical regions of Australia and India.t The nummulitic formation of this era is of world-wide extent, and contains many corals of large size, of genera now common in tropical seas, some of the same fossil species ranging from Sinde in India to the West Indies. If, lastly, we turn to the Lower Hocene strata, we find in the London clay of the Isle of Sheppey fossil fruits of the cocoa-nut, screw-pine, and custard-apple, reminding us of the hottest parts of the globe; and in the same beds are six species of Nautilus, and other genera of shells, such as Conus, Voluta, and Cancellaria, now only met with in warmer seas. The fish also of the same strata, of which 50 species have been described by Agassiz, are declared by him to be characteristic of hotter climates, and among the reptiles are sea-snakes, crocodiles, and several species of turtle. SUPPOSED SIGNS OF ICE-ACTION IN TERTIARY TIMES. Upper Miocene Period.—Il have now endeavoured to give a brief sketch of the indications afforded by organic remains of the nature of the climate in the Pliocene, Miocene, and Eocene periods. Everywhere we have recognised a remarkable con- currence of evidence in favour of a higher temperature ; but our geological records are far too fragmentary to entitle us positively to assume that, in the course of so vast a succession of ages, there were no oscillations of temperature analogous to those which certainly occurred between the close of the Newer Pliocene period and our own time. Professor Ramsay, * Elements of Geol., 6th edit., p. 299. ft Elements, p. 288. 206 SIGNS OF ICE-ACTION IN TERTIARY TIMES. (Cu. X who has so successfully devoted much time and thought to the search for indications of glacial action in remote erag reminds us that a geologist must expect to encounter onan difficulties in such investigations. If, at some future era, when large portions of the existing continents shall hare been submerged and overspread with marine strata, and other parts of them destroyed by denudation, we should have the task assigned to us of detecting those spots where ancient surfaces of rock had escaped destruction, or where erratic blocks and moraines of glaciers were extant, we might well despair of success. It rarely happens that we have oppor- tunities of examining terrestrial suriaces of high antiquity, and when visible, their extent is always very limited. In the majority of cases they will consist of rocks incapable of re- ceiving and preserving a glacial polish and striation. The least evanescent of the proofs of ice-action which our era is likely to transmit to future ages are, unquestionably, those large angular erratics which have been carried to great distances from their parent rocks ; and wherever such masses occur in older strata they deserve particular attention. I shall pro- ceed, therefore, to describe a formation of Miocene date, which Ihave myself examined, in which the position and size of the included blocks is such as to make it impossible at present to account for their transportation by any cause other than the buoyant power of ice. The marine strata alluded to consist of strata of sandstone and conglomerate, and constitute a member of the Miocene formation of the Collina of Turin, a chain of hills in the suburbs of the capital of Piedmont, on the brow of which ‘ stands the church of the Superga. These strata have long been celebrated for containing a plentiful store of fossil shells of the same species as those of the faluns of Touraine, Bor- deaux, and Vienna. The annexed diagram will give the reader some idea of the position of this conglomerate (@), which is highly inclined and conformable to the other strata which dip on each side to the north-west and south-east from the axis of the chain. I examined the district in 1857, im company with Signor Gastaldi, one of the ablest of the Italian geologists, and well versed in glacial phenomena. Ge] UPPER MIOCENE PERIOD. 207 On this occasion I satisfied myself that Signor Gastaldi was right in supposing that the large blocks f/f, lying on the surface of the hills, had been washed out of the beds Fig. 8. Alps. fa! Sal wee wm Ss -—G ; f \ Hill of Superga. NX 2 aS aes Section from the Alps a es Hill of the elles PR the position of e Miocene erratic blo . Conglomerates of Miocene age w vai large blocks. Marine sub-Apennine or Pliocene strata. Diluvium or ancient ate Of various ages, some of it below the morait ne d. . Moraine of Ivrea of the elect panos with erratic blocks. Erratic blocks lying on the moraine a . Miocene blocks w ee out of th 1€ conglomerate a, and scattered over the hills of the erga N.B.—The distance nee ae ive to the Hill of Turin is about thir ty miles. ty TAs A 8 a a, by the same action which has hollowed out the valleys.* In other words, they have not been brought from a distance, as was once supposed, during the more modern or Post- pliocene Glacial period, like the erratics e, which rest on the moraine d, but have been washed out of the Miocene beds in the immediate neighbourhood, viz., the conglomerate a. This last is part of a regular series of strata, chiefly of sand of various degrees of coarseness, and of gravel, in which are rolled pebbles of greenstone (or diorite) limestone, porphyry, and some other rocks. Among them we occasionally meet with fragments of enormous size, composed of serpentine and greenstone, one of which I ascertained by measurement to be 14 feet in its longest diameter. Signor Gastaldi has seen another in the same formation, 26 feet long; they are angular, and several of those which I saw exhibited some faint striz and * Gastaldi, Sui Conglomerati Mioceni del Piemonte, 186]. 9208 SIGNS OF ICE-ACTION IN TERTIARY TIMES. [Cu. X had one of their sides polished, in a manner much resembling that produced by glacial action. The whole thickness of the beds through which these blocks are dispersed varies from 100 to 150 feet. As yet they have yielded no organic remains, but they are covered by strata containing shells of the Upper Miocene formation, and they rest on Lower Miocene strata for the most part of freshwater origin. The fauna and flora, both of the overlying and underlying rocks, have the same sub- tropical character as that of Miocene date in Switzerland and in Central Europe generally. Hence the hypothesis of the , transport of such huge blocks by ice-action has naturally been resorted to most unwillingly, but in the present state of our knowledge it is the only one which appears tenable. The beds of sandstone alternating with those in which the blocks are enveloped exhibit no signs of having been tumultuously accumulated as by a flood. The erratics seem rather to have fallen quietly into their places. The nearest spots where any similar serpentine and greenstone occur are about twenty miles to the westward, but there has been so much subsidence of the country during the Miocene period, so much subsequent depo- sition of overlying miocene, pliocene, and alluvial deposits, and such changes in physical geography, that we cannot form any probable conjecture as to the proximity or distance of the spots from which the blocks may have come. The absence of organic remains may possibly imply a sea chilled by floating ice, or by a cold current from the north ; but such an hypothesis is not very satisfactory, because the thickness attained by the conglomerate in some parts of Piedmont is very great, far ex- ceeding that seen in the vicinity of Turin. We must con- clude, therefore, that its accumulation occupied a great lapse of time, and if so, it is difficult to understand why there are no organic remains in it: for although the temporary influx of a cold current might well be supposed to annihilate a fauna fitted for a warmer sea, yet the long continuance of such a current would naturally fit the region for species such as thrive in the seas of colder latitudes. Perhaps a lofty mountain, with a glacier reaching the sea, would be the least objectionable hypothesis, since in Patagonia there is a glacier descending from the Andes in Hyre Sound, in the cin tis Cu. X.] ICE-ACTION IN THE EOCENE PERIOD. 209 latitude of Paris, and another in the neighbouring Gulf of Penas, lat 46° 50’, or the latitude of the Bernese Alps, both of which convey large erratic blocks to the Pacific, into which they are floated by numerous icebergs of large size. Supposed signs of ice-action im the Hocene Period.—In a bed of coarse conglomerate of the Hocene period in the Alps, phenomena in many respects analogous to those of the neigh- pourhood of Turin present themselves. This conglomerate is a subordinate member of that vast deposit of sandstone and shale which is provincially called ‘flysch,’ and which, by its position (for it is devoid of organic remains), seems referable to the middle or ‘nummaulitic’ portion of the great Eocene geries. The well-known ‘ Vienna sandstone’ is a member of this flysch, which extends for 300 miles at least, east and west, from Vienna to Switzerland, along the northern flanks of the Alps, and is again seen in the south, near Genoa, and in several parts of the Apennines. Its thickness is very great, amounting to several thousand feet, and occasionally, according to some authorities, 6,000 feet. It is often finely stratified, and singularly barren of fossil remains, although in a few places it contains fucoids. Here and there, as in the Sihlthal, near the lake of Zurich, and in the Toggen- burg in St. Gall, large blocks are enclosed in it, some of them angular and others rounded. These blocks are occa- sionally of limestone, and contain ammonites and other fossils of the oolitic and liassic formations, as described by Dr. Bachmann.* Blocks also of a red variety of granite of a peculiar composition, unknown in situ in any part of the Alps, occur in the same conglomerate of the flysch. In Several places the blocks are 10 feet long, but at Habkeren, on the north side of the lake of Thun, many are seen of enor- nous dimensions, one of them being 105 feet in length, 90 in breadth, and 45 in height. They have lost their edges, either by friction or decomposition, but are not polished or striated. There has been a lively discussion as to whether the largest of the above-mentioned Habkeren blocks came out of the lysch, or were simply erratics of the Glacial period ;+ but oo. Petrifakten und era we Leginnaey Structure of Alps, Quart. thils ond To eat Flysch des Sihl- Geol. Journ., vol. v. 1849 VOL, A 5 g. a 210 ICE-ACTION IN THE EOCENE PERIOD. (Cae Escher von der Linth, Studer, Riutimeyer, and Bachmann are clearly of opinion that they have been washed out of the coarse conglomerate. The flysch of Bolgen, near Sonthofen, also contains foreign blocks of considerable size, but neither on them nor on any others have any glacial strie been as yet observed. We have to account not only for the wonderful size of the granitic blocks, varying from 10 to 100 feet in diameter, but for the distance which they have travelled, which seems to be implied by our inability to refer them to any known source. They are distinguishable by their mineral character from all granitic erratics of the true or modern glacial period, such as are strewed over the surface of those districts of Switzerland where there is no outcrop of flysch conglomerate. It has been always objected to the hypothesis that these huge masses were transported to their present sites by glaciers or floating ice, that the Hocene strata of nummu- litic age in Switzerland, as well as in other parts of Europe, contain genera of fossil plants and animals characteristic of a warm climate. It has been particularly remarked by M. Desor, that the strata most nearly associated with the flysch in the Alps are rich in echinoderms of the Spatangus family, which have a decidedly tropical aspect. The entire absence of shells, or of organic remains generally, may perhaps be thought to favour a glacial origin for the flysch, but this negative cha- racter is too common in strata of every age to be of much value, except in connection with other proofs of intense cold. Nor must we disguise from ourselves the fact, that in the seas of polar regions where icebergs abound at present there is by no means any dearth of animal life. Onthe other hand, the regular stratification and even fine lamination of portions of the flysch cannot be said to be inconsistent with a glacial origin, for on the Norfolk coast we see thinly laminated clays devoid of organic remains forming an integral part of un- questioned glacial drift. The great thickness of the flysch and the fucoids preserved in a few beds of it, leads to the conclusion that it was of marine origin. To imagine icebergs carrying such huge fragments of stone in so southern a latitude, and ata period immediately preceded and followed by the signs of a warm {done TeC os fe Xi] ICE-ACTION IN THE EOCENE PERIOD. 211 climate, is one of the most perplexing enigmas which the geologist has yet been called upon to solve. It would per- haps be most in accordance with existing analogies to sup- ose a mountainous island occupying the site of the Austrian. and Swiss Alps from which glaciers descended to the sea. For in the southern part of New Zealand, between latitudes 43° and 44° S. in the middle island, glaciers coming from Mount Cook, the loftiest mountain of a snow-covered chain, reach to within 500 feet of the sea, and the same region is inhabited not only by tree-ferns but by an Areca palm. These plants of tropical aspect are now seen flourishing in this district, very near to moraines and angular feipitfons ts of stone recently brought down by ice from the higher regions. CHAPTER XI. FORMER VICISSITUDES IN CLIMATE—continued. WARM CLIMATE IMPLIED BY THE FOSSILS OF THE CHALK-——CRETACEOUS REPTILES—HOW FAR EXTINCT GENERA AND ORDERS MAY ENABLE US TO TEMPORARY MAMMALIA WILL NOT EXPLAIN THE PREDOMINANCE OF REPTILES H IN HIG TITUDES—-PERMIAN FOSSILS—-SUPPOSED SIGNS OF ICE-ACTION I THE COAL PERIOD—FOSSIL SHELLS AND CORALS OF THE CARBONIFEROUS STRATA—CLIMATE IMPLIED BY THE REPTILES OR AMPHIBIA OF THE CoOAL— DEVONIAN PERIOD, AND SUPPOSED SIGNS OF ICE-ACTION OF THAT ERA CONSIDERED— CLIMATE OF THE SILURIAN PERIOD—CONCLUDING REMARKS ON THE CLIMATES OF THE TERTIARY, SECONDARY, AND PRIMARY EPOCHS. In the last chapter I endeavoured to trace back the history of the changes of climate from modern times to the Hocene period, and we found, that before we had carried back our re- trospect as far as the Newer Pliocene deposits, proofs already presented themselves, both organic and inorganic, of a tem- perature much colder than that now prevailing in European latitudes. Although this Glacial epoch, as it has been called, lasted for thousands, if not hundreds of thousands of years, it was of so modern a geological date as to belong almost exclu- sively to the time when the shells were the same as those now living. The geographical range only of species was different, because an arctic fauna was enabled by aid of the cold to invade the temperate latitudes. An examination of the fossils of the Pliocene, Miocene, and Eocene strata, viewed successively in unopoly wt ammo} hte Edy “apondin Cu. XI] WARMTH IMPLIED BY FOSSILS OF THE CHALK. 213 the order of their higher antiquity, afforded us evidence of temperature continually increasing in proportion as we receded farther from the Glacial epoch. If, in certain locali- ties in or near the Alps, some huge transported fragments of rock, enclosed in miocene and eocene conglomerates, seemed to require the aid of ice to bring them into the sites they now occupy, a local combination of geographical circumstances may perhaps be conceived, which might account for such exceptional cases without requiring a general refrigeration of climate at the times alluded to. Warm climate implied by the fossils of the Chalk.— When we pass beyond the gap which divides the Tertiary from the Secondary formations, we observe in the cretaceous strata signs of a warm climate similar to those previously derived from tertiary plants, shells, corals, and reptiles. Many of the principal members of this cretaceous series have been traced from the 57th degree of latitude in the north- ern hemisphere to districts which approach within 10 or 12 degrees of the equator, as at Pondicherry, Verdachellum, and Trichinopoly. In these countries deposits occur, which by their ammonites and many other fossils were identified by the late Edward Forbes as belonging to beds, some of them corresponding to our English gault, and others to formations which immediately overlie and underlie the same gault.* In these Indian formations are found shells of the genera Cypreea, Oliva, Triton, Pyrula, Nerita, and Voluta, which belong to forms now characterising tropical seas, and some of which only made their first appearance in European latitudes in the uppermost or Maestricht chalk. The geographical birth- place, says Forbes, of these genera seems to have been first in the tropics before the Tertiary period, during which last they made a great figure in Europe throughout Hocene and Miocene times, retreating again southwards in the Newer Pliocene era, when the cold of the approaching Glacial epoch had begun to make itself felt. The plants of the Upper Cretaceous formation of Europe, 80 far as they are known, have such an affinity with the Eocene * See Report on Fossils collected by ton, Quart. Geol, Journ., 1845, vol, 1, C.J. Kaye, Esq. and Rev. W. H. Eger- pp. 79. 214 CRETACEOUS REPTILES. [Cx. XT, flora as to point in the same direction in regard to the existence of a high temperature. They contain a large number of dicotyledonous angiosperms, whereas the Lower Cretaceous rocks are characterised by the absence of these last, and by a predominance of cycads and of conifers of an araucarian type, and of ferns referred by some botanists to genera which favour the hypothesis of a warm climate. In reasoning on the organic remains of the Upper Mio- cene strata of Central and Southern Europe, we had the advantage of drawing our inferences as to the high tempera- ture of the atmosphere and ocean from shells, one-third of which were of living species, while our conclusions were con- firmed by contemporaneous genera of plants, insects, and corals, besides the presence of apes and monkeys. The reptiles also were more numerous, some of them of larger size than are now found in temperate regions. In the Lower Miocene formation, crocodiles, chelonians, and large batra- chians, and in the Kocene deposits the same genera of reptiles, together with sea-snakes, bore testimony in like manner to the warm temperature of the seas, lakes, and rivers. Cretaceous reptiles—When we pass on to the uppermost member of the Cretaceous series, or the Maestricht chalk, as it is called, we find a similarly marked development of reptile life in regions where nothing analogous is now to be met with. Thus, in latitude 51° N., we encounter in St. Peter’s Mount, Maestricht, the aquatic reptile called Mosasaurus, which was twenty-four feet in length. The same genus appears in the American chalk, from the various divisions of which Dr. Leidy has also obtained more than twenty genera of reptiles, most of them extinct, but some, like the tortoises (Trionyx and Emys),and the crocodiles of living types.* Several of the crocodiles of this age, both in Europe and America, are proceelian, that is to say, they have the anterior portion of each vertebra concave, and the posterior part convex, in which respect they agree anatomically with the existing species, and are contrasted with a large number of the fossil genera of that family, The reader will observe, on consulting Owen’s * Leidy, Cretaceous Reptiles of United States. Smithsonian contribution, 1860. Howe far { has bee ‘}innologi 4 distant Cx. XI] EXTINCT ORDERS INDICATE TEMPERATURE. 915 a 7 7S table of the distribution of reptiles in past geological ages, that of the five living orders, crocodiles, lizards, tortoises, snakes, and frogs, the two last mentioned do not extend into the Secondary or Mesozoic periods, but the three first, the Crocodilia, Lacertia, and Chelonia, are met with in full strength in Cretaceous times, where they become associated with no less than three extinct orders, namely, Pterodactyls, [chthyosaurs, and Plesiosaurs. Respecting the first of these, namely, the flying reptiles, it has been argued, with some show of reason, that we have no right to assume that they requirel a hot climate, because they are so highly organised, and have so near an affinity to birds in structure, that they may have been warm-blooded, and as capable as pirds of sustaining great cold. But the same argument will not apply to ichthyosaurs or to plesiosaurs, nor to the numerous chelonians which occur in the different divisions of the Cretaceous period, including the Wealden strata, in which large terrestrial saurians are so conspicuous. How far extinct orders and genera may indicate temperature.— It has been objected, that in speculating on the habits and physiological constitution of plants and animals of an epoch so distant from our own as the Cretéceous, we enter a region of doubt and uncertainty, because even the eocene species are distinct from the living ones, while the creta- 2 -eaous fossils differ as much from the eocene as do the latter from living types. Dr. Fleming, therefore, when engaged in a controversy with Dean Conybeare, in 1830, as to the proofs of a hotter climate in the olden time, declared that the reasoning of his opponents was illogical, and their mode of dealing with the subject unfair. ‘They were playing,’ he said, ‘with loaded dice;’ for the larger number of generz are now in tropical and sub-tropical zones, not because they could not live in colder regions, but simply because the land and sea in those zones is of wider extent, and supports in equal areas a greater exuberance and variety of animal and vegetable forms. According, therefore, to the doctrine of chances, the majority of the genera of any past epoch, whether they be * Owen, Paleontology, p. 321, 216 FLOATING ICE IN SEA OF THE WHITE CHALK. [Cu, xr. extinct or not, will have their nearest living analogues in hot countries. Many of them will be unrepresented in the colder parts of the globe, not because of their unsuitableness to the climate of such regions, but because of the comparative poverty of the fauna and flora of high latitudes. The fact, it is said, that the same genus has often species proper to the torrid, temperate, and frigid zones, is enough to demon- strate that it is on species alone that we can rely in ques- tions of climate.* The caution here enjoined is by no means to be disregarded, but our scepticism on this head may be carried too far. Tf three assemblages of existing species were submitted toa good naturalist, one of them coming from arctic, another from tem- perate, and a third from tropical latitudes, he would be able at once to assign the quarter from which each of the three groups had been obtained, even though he might never have seen any one of the species before. He would be guided partly by the presence of certain genera and orders, and partly by the absence or feeble representation of others in each group. It is by reasoning of this kind that we are able to arrive at conclusions respecting the temperature of periods when most of the genera Mid many even of the orders of plants and animals differ from those now living, and it must be remem- bered that when we study the modern Tertiary formations, in which a considerable proportion of the species are identical with living ones, we are able to infer from their associates what was the climate of many species and genera of animals and plants long since extinct. By this means, our data of comparison, when we are endeavouring to interpret the monu- ments of antecedent epochs, are greatly increased, since it is not merely to the living creation that we can appeal. Hvidence of floating ice in the sea of the White Chalk m Hngland.—The homogeneous character of the white chalk or upper portion of the great Cretaceous formation throughout a large part of Kurope is now explained by the discovery that it is made up almost exclusively of the remains of the cal- careous shells of Foraminifera, while the silicious portions WwW ‘Cu. XI.] FLOATING ICE IN SEA OF THE WHITE CHALK. 9°17 have been derived chiefly from plants called Diatoms. It was ascertained, when soundings were made for the Electric Tele- graph, that calcareous mud of a similar character and origin is now forming over vast areas in the depths of the Atlantic. The general absence from the white chalk of sand, pebbles, drift-wood, and other signs of neighbouring land, is thus ac- counted for, but the occasional discovery of single and per- fectly isolated stones, usually consisting of quartz and green schist, in the south-east of England, has naturally excited much surprise. In what manner could such stones have been carried far out into an open sea, SO as to fall to the bottom without any admixture of other foreign matter? I formerly endeavoured to explain this enigma by referring to a fact observed by Mr. Darwin, namely, that stones of considerable size are occasionally entangled in the roots of floating trees, and transported to great distances in mid-ocean. One of them, as big as a man’s head, was conveyed in this way for 600 miles to Keeling Island, a small ring of coral in the Indian Ocean. Seaweed also, called Kelp, Fucus vesiculosus, | when uprooted, frequently bears along with it from shallow water pebbles and earth around which its roots have grown. But, on reconsidering all the facts now observed, I agree with Mr. Godwin-Austen that there are some cases which we cannot account for without introducing the agency of ice. Thus, for example, in 1857, there was found at Pur- ley, near Croydon, in the body of the white chalk, a group of stones, the largest of which consisted of syenite, a rock com- posed of augite and felspar. This block had been broken up by the workmen before it was examined by any scientific ob- server, but the largest of the fragments was ascertained to be twelve inches in diameter in two directions, and to weigh up- wards of twenty-four pounds. It was surrounded by eranitic sand and pebbles of greenstone, and its dimensions rendered the hypothesis of transportation by drift-timber inadmissible. There was, moreover, a total absence of carbonaceous matter, such as might have been looked for if a waterlogged tree had sunk on the spot. Mr. Godwin-Austen, therefore, has Suggested that the pebbles and sand must have been frozen into coast-ice, and then floated out to sea, and the stones, he. 218 CLIMATE OF THE OOLITIC AND TRIASSIC PERIOD S. [Cu. XT. observes, mineralogically considered, present just such an assemblage as might now be found on a beach on the coast of Norway in lat. 60° N. As to the degree of cold required for the formation of such coast-ice, it may not, the same author remarks, have exceeded that occasionally experienced in our times on the eastern coast of England, from which ice has lifted and floated away far greater weights.* Another example of a rounded block, weighing above thirteen pounds, had been previously noticed in the ‘chalk with flints,’ by Mr. Catt, in a pit near Lewes. Attached to it was Spondylus lineatus, with serpule and some bryozoa. It had evidently been rolled before transportation, and before the serpulz had fixed themselves on it. No large angular blocks have as yet been met with in the white chalk such as might imply the agency of glaciers and icebergs. Climate of the Oolitic and Triassic Periods:—When we en- quire into the climatal state of the globe in times which preceded the Cretaceous, we find a very general agreement among zoologists and botanists as to the warmth of Huropean latitudes in the Oolitic and Triassic eras. The vegetation of these periods consists chiefly of cycads, conifers, and ferns. Professor Heer remarks, that the tree which is most common in the Upper Trias in Switzerland has a near affinity to a living African species of Zamia,+ and M. Adolphe Brongniart had long before expressed his opinion that the plants of the secondary periods favoured the hypothesis of a climate like that of the West Indies. The same genera, and, to some extent, the same species of ammonites and some other shells proper to oolitic strata in Europe, occur also in formations of the same age in India, as, for example, in Sinde and in Cutch, lat. 22°N. Ina northerly direction the same forma- tions reach within 134 degrees of the pole, as was shown by the fossil specimens brought home by Capt. McClintock. Among these the Rev. Samuel Haughton recognises a species closely allied to the Ammonites concavus of the Lower Oolite which was found at Prince Patrick’s Island, lat. 77°10’ N. In Cook’s Inlet also, lat. 60° N., several ammonites of jurassic types, if not species, were obtained, and Belemnites pawillosus, * Geol. Quart. Journ., vol. xiy., 1858, ft Heer, Urwelt der Schweiz, p. 1. ns os" , ih cu, XL] MANY REPTILES IMPLY WARM CLIMATE. 219 British liassic fossil. But what is far more remarkable, remains of a large ichthyosaurus of liassic type were brought from an island in lat. 77° 16’ by Sir Edward Belcher. They have been described and figured by Professor Owen, and as some of the vertebrae were 24 inches in diameter, the animal must have been of considerable size.* Abundance and variety of reptiles implies warm climate.— The reptiles of the Oolite and Lias, and of the still older Trias, are so numerous and diversified in form that the period of the secondary or mesozoic rocks has been called the age of reptiles. The number of marine genera alone exceeds fifty, while that of the freshwater and terrestrial species, including those of aerial habits, is almost as great as the tribes which peopled the sea. Some of these were more highly organised than any animals of the same class now living, as the Belodon, for example, of the Upper Trias, a saurian about the size of the largest living crocodile, but which belonged to the extinct order of Dinosaurians. Hermann von Meyer ascertained, in 1866, that it possessed breathing apertures or spout-holes like the whale, so that we might imagine it to have been capable of sustaining a cold climate were it not associated with many reptiles of lower evade, as well as with shells, corals, and plants which be- speak a high temperature. On the whole, no less than eighty reptiles have been described by Hermann von Meyer, all derived fromthe Trias of Germany alone. They belong entirely to extinct orders, but all of which, according to Owen,} display affinities more or less decided to living fa- milies of the same class, while in the overlying liassic and oolitic groups we find representatives of the crocodilian and chelonian orders, which still exist together with members of four extinct orders. These exhibit various grades of organi- sation, and the analogy of the living creation is strongly in favour of their having flourished in a climate in which the heat was considerable during part of the year and the winter brief and never severe. Thus, in some of the temperate regions of the southern * Last of Arctic Voyages. tion of reptiles in Owen’s Paleontology, + Seea table of geological distribu- p. 321, 2nd edit., 1861. 220 MANY REPTILES IMPLY WARM CLIMATE. [Cisse hemisphere at present, where the winters are long and the summers cool. there is an entire absence of reptile life— in Tierra del Fuego, for example, and in the woody region immediately north of the Straits of Magellan (between lati- tudes 52° and 56° §.), and in the Falkland Islands. Not even a snake, lizard, or frog, are met with; although in these same countries we find the guanaco (a kind of llama), a deer, the puma, a large species of fox, many small rodentia, and, in the neighbouring sea, the seal, together with the porpoise, whale, and other cetacea. In the arctic regions, at present, reptiles are small, and sometimes wholly wanting, where birds, large land quadru- peds, and cetacea abound. We meet with bears, wolves, foxes, musk-oxen, and deer, walruses, seals, whales, and narwhals, in regions of ice and snow, where the smallest snakes, efts, and frogs are rarely, if ever, seen. The power of reptiles to bury themselves in the earth, and to hybernate in a state of torpidity, enables them to exist in extra-tropical regions, but not where the winter’s cold is excessive or of long duration. Absence of mammalia does not explain the wide range of reptiles.—In none of the secondary rocks, as before stated, have any mammalia clearly referable to the placental division been found, whether of terrestrial or aquatic genera. Their absence may partly account for the extraordinary number of genera, species, and individuals of the reptile class. For the reptiles enjoyed in those periods a monopoly of a large portion. of the habitable surface which they are now obliged to share vith the more powerful mammalia. In the struggle for existence they had only to compete with marsupials of very diminutive size, and, so far as we know, there were few con- temporary birds, so that to a great extent thereptiles performed the functions in the air, on the land, and in the water, which the two highest classes of vertebrata now discharge. But granting that the predominance of reptiles is checked in our days by the important part played by the more highly organised verte- brata, we can by no means attribute the present scarcity of crocodiles, iguanas, lizards, tortoises, snakes, and the larger batrachians in high latitudes, as contrasted with their Cu. XI.] REPTILES OF THE GALAPAGOS ARCHIPELAGO. 221 abundance in secondary periods, to the progress which the animate world has made in that great interval towards a more All the above-mentioned orders of highly organised state. reptiles are able to maintain their ground at present against the ape, elephant, rhinoceros, tiger, deer, and other mam- malia, large and small, in all zones where they are favoured by sufficient heat. If they are absolutely wanting in polar re- gions it is evidently not the competition of the bears, musk- puffalos, walruses, and whales which sets a limit to their range sn that direction, but the power of frost. There is no area in the globe at present, between the parallels of 40° and 60°, where a climate exists like that which we may suppose to have prevailed when the triassic and oolitic rocks were formed. But perhaps the nearest approach to it may be found in the Galapagos Archipelago, which is situated nearly 600 miles west of the coast of Peru, and which con- tains some islands from 3,000 to 4,000 feet high, and one of them 75 miles long. Placed under the equator, the heat is greater than in temperate latitudes, but it is moderated by the surrounding ocean, and by a current of cold water which flows from Patagonia northwards along the west coast of South America. This archipelago has been called the land of reptiles, from the extraordinary number of large tortoises, together with lizards and snakes, which it supports. Among the lizards are two species of a peculiar genus, called Am- blyrhincus, one of them terrestrial and the other aquatic. The latter is marine, laying its eggs in the seaweed under water; it affords the only living example, with the exception of some sea-snakes, of a reptile proper to the ocean, and 1 serves to show that the existence of seals and cetacea, which abound in the Pacific, form no bar to’ the coexistence of aquatic reptiles in the same region. The number of indi- vidual tortoises and other reptiles could not possibly be so oreat in these islands, were it not for the absence of mam- malia, for a single indigenous species of mouse is the only re- presentative of this class in the Galapagos; in which respect we have a state of things strictly analogous to that of the secondary periods before alluded to. The rich marine fauna of the St. Cassian beds in the 222 PERMIAN FOSSILS. [Ci. XT Austrian Alps affords evidence, by the large size of its am- monites, orthocerata, and other shells, that in the east of Europe the seas enjoyed a warm climate, at the same time that in the west the triassic reptiles before mentioned were swarming on the land and in the rivers and estuaries. This St. Cassian fauna is known to extend as far north as lat. 55°, and has been traced as far south in India as the Himalaya mountains in lat. 30°, showing that the elevated temperature alluded to was of wide geographical extent. Triassic conglomerate.—The great size of some fragments of rock in the New Red Sandstone, probably of Triassic age, in Devonshire, has led Mr. Godwin-Austen to refer their transport to ice-action; but this opinion. has been contro- verted by Mr. Pengelly,* who has shown that such masses may not have travelled far, and are such as might have been moved by breakers beating against a wasting cliff. Permian fossils—Between the Triassic and Permian rocks there is a break which doubtless implies a great lapse of time, of which the records are wanting, in that part of the globe as yet best known to the geologist. It constitutes the line of division between the primary and secondary, or between the Paleozoic and Mesozoic formations. The Permian rocks have been traced as far north as Petschora-land in Russia between lat. 65° and 70° N. They occur largely in Germany and England; and in North America have been traced as far south as Kansas and Nebraska, lat. 44° N. Amongst the Permian shells we find the genera Nautilus and Orthoceras, and these are sometimes accompanied by large reptiles of a family called Thecodonts, which combine in their structure many characters of the living crocodiles and lacertians. They are most nearly allied to the Varanian Monitors, which now inhabit tropical countries. The fossil plants of the Permian formation are very like those of the antecedent carboniferous strata, of which I shall presently speak, and indicate the prevalence of a warm and moist climate throughout a great part of the northern hemisphere. Supposed signs of ice-action in the Permian Period.— Pro- fessor Ramsay, in an able memoir published in 1855, gave * See his Paper on the Red Sandstone Conglomerates of Devonshire, part 1. Cu. XI.] ICE-ACTION IN .THE PERMIAN PERIOD. 293 (2) an account of observations made by him on a brecciated conglomerate of Permian age in Shropshire, Worcester- shire, and other parts of England, which had led him to infer the action of floating ice in the seas of that remote period. His arguments are founded on the following facts:—the fragments of various rocks imbedded in these breccias are often angular, and of large size, some of them weighing more than half a ton; they are very often flat- sided, and have one or more of their surfaces polished and striated. They are generally enveloped in a red unstra- tified marl, in which they lie confusedly, like stones in boulder-drift. In some cases it can be demonstrated that the nearest points from which these stones could possibly have been conveyed are the mountains of Wales, more than twenty, thirty, or even fifty miles distant ; and it is in- ferred that the only way in which they could have retained their angular shape, after being transported so far from their original position, is by being carried by floating ice. Some of the specimens also taken by the Professor out of the breccia, and now exhibited in London, in the Jermyn Street Museum, have their surfaces rubbed, flattened, and furrowed, like stones subjected to glacial action. One of the most characteristic of these specimens was obtained from a spot about six miles south-east of Bridgenorth, near the village of Enville in Wor- cestershire. The fragment is six inches in its longest diame- ter, consists of hard dark Cambrian grit, with a smoothed surface, exhibiting parallel sets of striz in more than one di- rection,* a newer set crossing the older one. I have visited a great many of the localities where these Permian breccias occur, and have observed all the phenomena above alluded to, except that I scarcely ever found a large fragment ‘in situ, and never one large or small with a polished and striated sur- face ; but my failure to discover examples of these last-men- tioned appearances is simply a proof that they are by no means Common, which may be said in regard to glaciated stones in the terminal moraines of many modern glaciers. I am fully satis- fied that such fragments have been taken out of the breccia, and the explanation offered by Professor Ramsay appears to * Ramsay, Quart. Geol. Journ., vol. ii. 1855. 224 CLIMATE OF CARBONIFEROUS PERIOD. [ Cu. XL. me the most natural, indeed the only one in the present state of science which can be suggested. That glaciers should have reached the sea in lat. 53°, in England, cannot gur- prise us when we see them coming down at present to within 500 feet of the sea in New Zealand, in lat. 44°, or much nearer the equator ; and it has been already stated, p. 211, that tree-ferns and even palms now flourish in New Zealand, in the immediate neighbourhood of these glaciers. It should also be borne in mind, that there is a great dearth of fossil remains in the Permian conglomerates of Central England ; and we know not by what plants or animals the lands and seas were inhabited at the time of their accumulation, and, consequently, we are ignorant, so far as we depend on organic evidence, of the nature of the climate which prevailed in that part of the Permian era, when the stones which have ap- parently been glaciated were carried to their present sites. Climate of Carboniferous Period—fossil plants.—If we next consider the climate of the Carboniferous period, we shall find that botanists have considerably modified the ideas which they originally entertained respecting the tropical tempera- ture supposed to be indicated by the fossil plants of that era. The fruit called Trigonocarpon, occurring in such profusion in the coal measures, was at first referred to the palm tribe, till the discovery of more perfect specimens enabled Dr. Hooker to decide that it was not a palm, but more probably belonged to a taxoid conifer, somewhat like the Chinese Sa- lisburia. The structure of the coniferous wood preserved in these strata exhibit some points of analogy with the Arau- earle of Chili, Brazil, New Holland, and Norfolk Island. The preponderance of ferns, several of them belonging to arborescent genera, such as Caulopteris, Zippea, Sphal- mopteris, and Stemmatopteris, would incline us to think, according to the analogy of the living creation, that the cli- mate was warm, moist, and equable, for tree ferns are now most abundant in islands of the tropical ocean, although some species extend in New Zealand, as before stated, as far towards the antarctic regions as the 46th degree of south latitude. Next to ferns, the Sigillariz and Lepidodendra are the most common vegetable forms. The fruit of Sigil- Cu. XI.] CLIMATE OF CARBONIFEROUS PERIOD. 995 Jaria is unknown, but the genus is regarded by Hooker as a highly developed cryptogam, having considerable afiinity with the fern tribe. The Lepidodendra belong to the same order as the living Lycopodia, and that these two families should be represented by numerous species of the size and height of forest trees seems to imply a warm and humid climate in the latitudes where they flourished. As to the geographical range in the northern hemisphere of this ancient flora, it is already ascertained that it extends from Alabama in the United States in lat. 30° to the arctic regions, while it has been traced in Europe from central Spain in lat. 38° to Scotland in lat. 56°. In the arctic regions it was first observed in Melville Island, in lat. 75°, during Capt. Parry’s expedition. The plants then collected were examined by the late Dr. Lindley, who recognised them as true fossils of the ancient coal.* The whole collection has unfortunately been lost, but among other fossils since brought from the same island by Sir Leopold McClintock, Heer has recognised ferns of the genus Schizopteris, a form character- istic of the ancient coal. Middendorf found Calamites canne- formis in a very high latitude near the mouths of the Lena. In Bear Island, lat. 74° 36’ N., midway between Spitzbergen and the North Cape, in about the same parallel as Melville Island, Von Buch has described strata of the Coal period containing characteristic marine fossils, and wnderlying these rocks he mentions that shales occur in which there are well- preserved ferns of the genus Pecopteris. After what was said at p. 203 of the spread of the Miocene flora over the arctic regions, and its near approach to the North Pole, the reader will feel no surprise at finding that in times long antecedent there was an equally vigorous ve- getation in the same latitudes. The coal plants were of different genera, and some few of them perhaps of different orders, from any now existing, and they may therefore have been endowed with a constitution enabling them to accom- modate themselves to a long polar night. We know, by experiment, that plants which are natives * Penny Cyclopzedia, art. Coal Plants. VOL. 1, Q 226 CLIMATE OF CARBONIFEROUS PERIOD. [Cu. XI of the tropics can dispense more easily with the bright light of those countries than with the heat of the same. Few palms can live in our temperate latitudes without pro- tection from the cold; but when placed in hot-houseg they grow luxuriantly, even undér a cloudy sky, and where much light is intercepted by the glass and frame-work, At St. Petersburg, in lat. 60° N., many tropical plants have been successfully cultivated in hothouses, although there they must exchange the perpetual equinox of their native regions for days and nights which are alternately protracted to nineteen hours and shortened to five. How much farther towards the pole even the existing species might continue to live, provided a due quantity of heat and moisture were sup- plied, has not yet been determined; but St. Petersburg ‘is probably not the utmost limit, and we should expect that in lat. 65° at least, where they would never remain twenty-four hours without enjoying the sun’s light, they might still exist. M. Adolphe Brongniart has observed that the great nu- merical preponderance of ferns over other forms of vegeta- tion in the Carboniferous era gives us ground to conclude that the climate was warm and moist. It must be confessed that this reasoning loses some of its force when we consider that the ancient flora is almost entirely destitute of those flowering plants which now constitute three-fourths of the living vege- tation. The ferns of the Coal period had fewer rivals to com- pete with, and more space in which to develope themselves freely ; still, analogy would lead us to ascribe a luxuriant growth of ferns, many of them arborescent, to a period when the humidity and warmth of the air were great. The same may be said of the other vascular cryptogams which, together with the ferns, form nineteen-twentieths of the carboniferous flora. They belong to families allied to ferns, such for ex- ample as the Sigillarix, Lepidodendra, and Calamites, and most of them attained a vastly greater size, and had a more complex structure, than any of their modern representatives. Their stems had also a lax tissue and, like living cryptogams of the same families, they must have derived the greater part of the water which entered into their composition, as well as their carbon, by their leaves from the air. They could 9 y 4 hp ye ‘ supp wy most d ‘dof car ithe eart won, AL nven als wsliferou iy ‘ame o ‘urats Ca. XI.] EXCESS OF CARBONIC ACID IN THE AIR. 997 =~ only flourish, therefore, in an atmosphere highly charged with aqueous vapour, and such an atmosphere must have been warm. Yet we must not suppose the heat to have been tropical, for hot sunshine, by promoting the decomposition of vegetable matter, is adverse to the formation of coal as it is to that of peat. Supposed excess of carbonic acid in the air.—That the air was charged with an excess of carbonic acid in the Coal period has long been a favourite theory with many geologists who have attributed partly to that cause an exuberant growth of plants. It has been said that there is ten times more carbon locked up in a solid form in the ancient coal measures than all that is now contained in the atmosphere; but granting the truth of this estimate, which is probably far below the mark, the inference deduced from it has always appeared to me most delusive. The atmosphere now receives large sup- plies of carbonic acid by gaseous emanations from the interior of the earth, which are most copiously given out in volcanic regions, and by volcanos during eruptions. Carburetted hy- drogen also escapes from beds of coal and lignite and other fossiliferous strata in which organic matter is decomposing ; the same gas evidently rising from great depths is also evolved from rents in the granitic and other crystalline rocks in which there are no organic remains. But it does not follow that the air is becoming more and more loaded with carbonic acid, for there are causes in action which prevent such a change in the constitution of the atmosphere. Wherever drift-timber is buried in the delta of a river, sea, or lake, or wherever peat is forming, we behold the process by which carbon is first ex- tracted by the powers of vegetation from the atmosphere, and then locked up permanently, or for ages, in the earth’s crust. As to the volume of carbonaceous matter which may thus be accumulated, it is a mere question of the time for which certain species of plants, together with the conditions fit for making peat and for burying drift-timber, may endure.* Some botanists are of opinion that the Sigillaria in the Carboniferous period played the same part which is now performed by the Sphagnum in Europe, both of them tending * See below, Chap. XVII, Q 2 998 FOSSIL SHELLS AND CORALS OF COAL PERIOD. Cn. xr. to relieve the atmosphere of part of the carbonic acid which is incessantly evolved from the interior of the earth. Mr, Darwin attributes the small quantity of peat formed in some regions of South America which are exceedingly damp to the absence of species of plants peculiarly fitted for its pro- duction. The abundance of coal, therefore, im certain dis- tricts may have arisen from the peculiarity of the vegetation, and of a climate which prevented decomposition, rather than from a peculiarity in the atmosphere which enveloped the globe in the Carboniferous period. In the Runn of Kutch there is a great annual deposit of salt caused by the evaporation of sea-water; but this arises from geographical causes wholly unconnected with the chemical condition of the ocean, which is not supposed to contain in that part of India more than its average proportion of chloride of sodium. The quantity of rock salt stored up in the Runn of Kutch, if that large district should be slowly subsiding, may in time exceed in amount all the brine now held in solution by the ocean, but if so, future geologists will have no right to conclude that during such an accumulation of chloride of sodium the waters of the sea were | more salt than they usually are. Nay, it would be even safer to conclude that in the region where so much rock salt was forming, the waters of the ocean would contain less than their average quantity of brine. Fossil shells and corals of the Coal Period—If we now turn from the flora to the fauna of the Carboniferous period, we find among the invertebrate animals many large chambered cells of Cephalopoda, as well as stone-lilies or encrinites, and corals, which bear a close affinity to fossil forms which flourished in those secondary periods, when, for reasons already explained, a warm climate is supposed to have prevailed, It may indeed be objected, in regard to the corals, that they all belong to a type only met with in the primary or paleozoic rocks; that is to say, to the order Zoantharva rugosa of Milne-Hdwards, which became extinct after the Permian era; but these cup and star corals of the older or quadripartite type have such a range, from tropical to northern regions, that unless we believe the seas in low latitudes to have had a cool temperature, we must suppose } hae whe: Wht for 4 3 tmaate (xu. XI.) REPTILES OF COAL—DEVONIAN PERIOD. DOG those in the north to have been far warmer than they are ow. : Reptiles of coal.—No representatives of the Vertebrata have been found in the Coal formation except reptiles and fish. The species of the former class are confined to two extinct orders, Ganocephala and Labyrinthodontia. Both of these depart widely from living types, but approach most nearly to the tailed batrachians of our time, to which the salaman- ders and certain perennibranchiate batrachians belong. All these are members of the sub-class Amphibia, which are regarded by many zoologists as intermediate between frogs and fish. Their nearest living allies are only found at present north of the equator; but in the northern hemisphere they have, according to Mr. Giinther, a wide range from north to south, in America, as wellas Europe and Asia. They are most numerously represented in genera, species, and individuals in the Southern United States, and in the table-land of Mexico. In Guatemala they have already become scarce, being re- duced to one or two forms. As to their extension in the oppo- _ site direction, some small species occur in the Canadian lakes; one of these, of the Menobranchus family, Giredon hiemalis, having been observed as far north as Lake Superior, in a place where the water was frozen over an inch thick every night for three months.* Such a geographical distribution is confirmatory of the conclusions as to climate to which we have been led by the plants of the Carboniferous era, as the tailed batrachians attain their fullest development between the 20th and 40th degrees of latitude, or in a warm zone free from intense heat or cold. Devonian Period.—In the antecedent Devonian period there are no reptiles, not even any of the order Amphibia. There are abundance of Ganoid fish, which have their nearest living analogues in the rivers of Northern Africa, for they are closely related to the African Polypterus, of which several Species are found in the Nile, and others in the rivers of Senegal. The Devonian, or Old Red crustaceans of the ex- tinct order Eurypteridz, attain some of them a length of five * Dr. Samuel Kneeland, Proceed. Boston Soe. Nat. Hist., vol. vi. p. 152. 250 ICE-ACTION IN THE DEVONIAN PERIOD, (Ce. XI, or six feet, and are therefore most comparable, in size at least, to crustaceans now living in Japan, and in regions still nearer the equator. The mollusca and corals resemble gene- rically those of the Carboniferous period. The Devonian flora is chiefly known to us through the labours of American geologists in the State of New York, and in Canada as far north as lat. 49°. More than sixty American species are enumerated by Dr. Dawson from that continent, and they com- prise, as we have seen (p. 149), so large a portion of the car- boniferous genera, as to point to a similarity of climate, The same may be said of the European plants of corre- sponding age, so far as they are known. Supposed signs of ice-action im the Old Red Sandstone, or Devonian Perwd.—The Rev. J. C. Cumming, in 1848, in his History of the Isle of Man, compared the conglomerate of the Old Red Sandstone to ‘a consolidated ancient boulder clay ;’ and more recently (1866), Professor Ramsay has pointed out that the conglomerate of the same age seen at Kirkby-Lons- dale, and Sedbergh, in Westmoreland and Yorkshire, contains stonesand blocks distinctly scratched, and with longitudinal and cross striations, like the markings produced by glacial ac- tion. I have myself examined this rock, and have seen blocks taken from it which exhibit such markings, some of them undistinguishable from those which I have observed on blocks taken from beneath a glacier. But Professor Ramsay has himself adverted to the fact, that the conglomerate above alluded to has been subjected to violent movements in dif- ferent directions, and to great pressure after it was buried under thousands of feet of carboniferous strata. In con- sequence of these movements, some markings have been pro- duced within the body of the rock itself, one pebble having occasionally been squeezed and forced against another, so as to indent it. Many of the pebbles also, and stones two feet and more in diameter, have acquired that polish which 1s called slickenside; and the same may be seen in various parts of the marly matrix, and even in the layers of carbonate of lime which have here and there been deposited in the imter- stices between separate stones. Scarcely in any district of England has there been a greater succession of rents and el pper : Ca. XU] CLIMATE OF THE SILURIAN PERIOD. 231 faults, and it is not a little difficult to decide in many cases to what kind of mechanical action many of the effects alluded to have been due. Some of the stones imbedded in the con- glomerate appear to have been derived from the mountains of Cumberland, and they may possibly have been polished, flat- tened, and scratched by glacial action, before they were trans- ported to their present site. But although inclined to adopt this explanation as proposed by Professor Ramsay, I think more evidence must be obtained before we can feel perfectly convinced that the markings in question have had a glacial origin. Climate of the Silurian Period.—When we enquire into the climate of the Silurian and older formations, we find our- selves deprived of some important classes of evidence on which we have relied when considering the organic remains of the formations of later date. Reptiles fail us entirely, as in the Devonian rocks; fish are wanting, except a few remains in the Upper Silurian; of plants there are none, and we must therefore be content to form our opinion as to the state of the climate from those genera of invertebrate animals of which there is a great profusion, but which usually in the primary strata, depart widely from living and tertiary types. The large chambered cephalopods, the corals, and the crinoids are so like those of the newer members of the Paleozoic series as to make us incline to believe that a similar temperature prevailed in the northern hemisphere, and a somewhat uni- form climate from equatorial to very high latitudes. Concluding remarks on climate.—The result then of our ex- amination in this and in the preceding chapter of the organic and inorganic evidence relating to the climate of successive geological periods is in favour of the opinion that a warmer temperature generally prevailed in the northern hemisphere from the 30th parallel of latitude to the pole than that now experienced. In the Pliocene era the fauna and flora of Cen- tral Europe were sub-tropical, and a vegetation resembling that now seen in Northern Europe extended into the arctic regions as far as they have been yet explored, and probably reached the pole itself. In the Secondary or Mesozoic ages, the predominance of reptile life, and the general character of 232 “CONCLUDING REMARKS ON CLIMATE, (Cu. Xt. the fossil types of this great class of vertebrata, indicate a warm climate and an absence of frost between the 40th parallel of latitude and the pole, a large ichthyosaurus having been found in lat. 77°16, and the general character of the mollusca and corals, as well as of the plants, being in perfect accordance with the inferences deduced from the fossil rep- tiles. If we then carry back our retrospect to the primary or Paleozoic ages, we find an assemblage of plants which imply that a warm, humid, and equable climate extended in the Carboniferous period uninterruptedly from the 30th parallel of latitude to within a few degrees of the pole, or to north- ern regions where at present the severe winter’s frost, and the almost universal covering of snow lasting for many months, preclude the existence of a luxuriant vegetation, In rocks older than the carboniferous, the evidence of plants, insects, and fish fails us, but the invertebrate fauna has such a generic resemblance to that of the later primary and the older secondary periods, as to force us to believe that the climate of the temperate and arctic regions was very ana- logous to that which generally prevailed in those subsequent epochs. But although the temperature was generally higher than it is now, we found a marked exception in the Glacial period intervening between Pliocene and modern times ; while some indications seem also to have been discovered of intercalated glacial periods of older date, especially in the Miocene, Hocene, and Permian eras, but no decided changes in the character of the organic remains have yet been shown to accompany the inorganic proofs of supposed glacial action of those remoter periods. “liseg of y of th lage he *“tinha CHAPTER XII. cam g VICISSITUDES IN CLIMATE CAUSED BY GEOGRAPHICAL CHANGES. ON THE CAUSES OF VICISSITUDES IN CLIMATE—ON THE PRESENT DIFFUSION N ANNUAL ISOTHERMAL LINES—DEPENDENCE OF HEAT OVER THE GLOBE-—MEA LAND AND SEA— oF THE MEAN TEMPERATURE ON THE RELATIVE POSITION OF CLIMATE OF SOUTH GEORGIA AND TIERRA DEL FUEGO—COLD OF THE ANTARO- qIC REGION—OPEN SEA NEAR THE NORTH POLE—-EFFECT OF CURRENTS IN EQUALISING THE TEMPERATURE OF HIGH AND LOW LATITUDES OLAR LAND ABNORMAL -——SUCCESSION OF GEOGRAPHICAL —THE PRESENT > LA es o a S ‘A ~ CHANGES REVEALED TO US BY GEOLOGY—MAP SHOWING THE EUROPEAN LAND WHICH HAS BEEN UNDER WATER SINCE THE COMMENCEMENT OF THE EOCENE PERIOD—ANTIQUITY OF THE EXISTING CONTINENTS— CHANGES IN’ GEOGRAPHY THICH PRECEDED THE TERTIARY EPOCH—-MAP OWING —FORMER GEOGRAPHICAL CHANGES WHICH MAY HAVE CAUSED THE FLUCTU- ATIONS IN CLIMATE REVEALED TO US y F ug DEPTH OF THE SEA AS COMPARED TO THE MEAN HEIGHT OF THE JESS OF CLIMATAL CHANGES. AND ITS CONNECTION WITH THE SLOWNE Causes of vicissitudes in climates.— As our retrospective sur- vey of the fossiliferous rocks of successive periods, given in the last two chapters, has led us to infer that the earth’s surface has experienced great changes of climate since it has been inhabited by living beings, we have next to enquire how such vicissitudes can be reconciled with the existing order of nature. The earlier speculators in geology availed them- selves of this, as of every obscure problem, to confirm their views concerning a period when the planet was in a nascent or half-formed state, or when the laws of the animate and inanimate world differed essentially from those now estab- lished; and in this, as in many other cases, they succeeded, to no small extent, in diverting attention from that class of facts which, if fully understood, might have led the way to an explanation of the phenomena. At first it was imagined 234 CAUSES OF VICISSITUDES IN CLIMATES, [Cx. XI. that the earth’s axis had been for ages perpendicular to the plane of the ecliptic, so that there was a perpetual equinox, and uniformity of seasons throughout the year; that the planet enjoyed this ‘ paradisiacal’ state until the era of the ereat flood; but in that catastrophe, whether by the shock of a comet, or some other convulsion, it lost its equipoise, and hence the obliquity of its axis, and with that the varied seasons of the temperate zone, and the long nights and days of the polar circles. When the progress of astronomical science had exploded this theory, it was assumed, that the earth at its creation was in a state of igneous fluidity, and that, ever since that era, it had been cooling down, contracting its dimensions, and acquiring a solid crust. It was also taken for granted that this original crust was the same as that which we are now studying, and which contains the monuments of a long series ‘of revolutions in the animate world. This notion, however arbitrary, was well calculated for lasting popularity, because it referred the mind directly to the beginning of things, and required no support from any ulterior hypothesis. But the progress of geological investigation gradually dissipated the idea, at first universally entertained, that the granite or crystalline foundations of the earth’s crust were of older date than all the fossiliferous strata. It has now been demon- strated that this opinion is so far from the truth that it is difficult to point to a single mass of volcanic or plutonic rock which is more ancient than the oldest known organic remains. Such being the case, the question of original fluidity, although a matter of legitimate speculation to the physicist, is one with which the geologist is but little concerned. It may relate to a state of things which preceded our earliest records by a lapse of ages many times greater than the entire series of geological epochs with which we are acquainted. If, instead of indulging in conjectures as to the state of the planet at the era of its creation, we fix our thoughts steadily on the connection at present existing between climate and the distribution of land and sea, and then consider what influence former fluctuations in the physical geography of the globe must have had on superficial temperature, we may Cx. XII.] DIFFUSION OF HEAT OVER THE GLOBE. 235 make a near approximation to a true theory. But the effect of former variations in the heat and cold of the different seasons in the year, caused by the precession of the equinoxes, combined with the revolution of the apsides, and still more by variations in the excentricity of the earth’s orbit, will have to be taken into account, as subsidiary to the more dominant influence of geographical conditions. Should doubts and obseurities still remain, they should be ascribed to our limited acquaintance with the laws of Nature, not to revolutions in ner economy. They should stimulate us to farther research, not tempt us to indulge our fancies respecting imaginary changes of internal temperature, or the unsettled state of the surface of a planet before it was prepared for the habitation of living beings. Diffusion of heat over the globe.—In considering the laws which regulate the diffusion of heat over the globe, we must be careful, as Humboldt well remarks, not to regard the climate of Europe as a type of the temperature which all countries placed under the same latitude enjoy. The physi- cal sciences, observes this philosopher, always bear the im- press of the places where they began to be cultivated; and as, in geology, an attempt was at first made to liken all the voleanic phenomena to those of Italy, so in meteorology, a small part of the old world, the centre of the primitive civilisation of Europe, was for a long time considered a type to which the climate of all corresponding latitudes might be referred. But this region, constituting only one-seventh of the whole globe, proved eventually to be the exception to the general rule. For the same reason, we may warn the geolo- gist to be on his guard, and not hastily to assume that the temperature of the earth in the present era is a type of that which most usually obtains, since he contemplates far mightier alterations in the position of land and sea, at diffe-_ rent epochs, than those which now cause the climate of Europe to differ from that of other countries in the same parallels of latitude. l It is now well ascertained that zones of equal warmth, both im the atmosphere and in the waters of the ocean, are neither 236 DIFFERENT TEMPERATURES [Cxu, XIr, parallel to the equator nor to each other.* It is also known that the mean annual temperature may be the same in two places which enjoy very different climates, for the seagong may be nearly uniform, or violently contrasted, so that the lines of equal winter temperature do not coincide with those of equal annual heat or isothermal lines. The deviations of all these lines from the same parallel of latitude are deter- mined by a multitude of circumstances, among the principal of which are the position, direction, and elevation of the continents and islands, the position and depths of the sea, and the direction of winds and currents. On comparing the two continents of Hurope and America, it is found that places in the same latitudes have sometimes a mean difference of temperature amounting to 11°, or even in a few cases to 17° Fahr. ; and some places on the two continents, which have the same mean temperature, differ from 7° to 17° in latitude. Thus, Cumberland House, in North America, see fig. 9, having the same latitude (54° N.) as the city of York in England, stands on the isothermal line of 82°, which we have to seek in Europe at the North Cape, in lat. 71°, but its summer heat exceeds that of Brussels or Paris.t The principal cause, says Humboldt, of the greater intensity of cold in corresponding latitudes of North America, as contrasted with Europe, is the connection of America with the polar circle, by a large tract of land, some of which is from three to five thousand feet in height; and, on the other hand, the separation of Europe from the arctic circle by an ocean. The ocean has a tendency to preserve * We are indebted to Alex. von Hum- boldt for having first collected together the scattered data on which he founded an approximation to a true t theory o the distribution of heat over the globe. Many of ised ee were sha a from the autho and many from the Satis of M. Bice ee ost, of Geneva, on the radiation of heat, and — tom. iii. translated in a Edin. Phil. Journ. vol. iii, Jy uly, 182¢ The map of Soe Lines, pub- lished by Humboldt and Dove in 1848, (re-edite a ae in 1853, from which fig. 9, is racted), supplies a large body of w cll established data for such Changes in the Earth’s Superficial Tem- perature.,—Q. Journ. Geol. Soc. 1852; p. 66. + Sir J. Richardson’s Appendix to Sir G. Bach’s Journal, 1843—1840, P. 478 autor, It quite ef “itntery it being ~ieing ray Cu. XII] OF CORRESPONDING LATITUDES. 937 everywhere a mean temperature, which it communicates to the contiguous land, so that it tempers the climate, mode- rating alike an excess of heat or cold. The elevated land, on the other hand, rising to the colder regions of the atmosphere, becomes a great reservoir of ice and snow, arrests, condenses, and congeals vapour, and communicates its cold to the ad- joining country. For this reason, Greenland, forming part of a continent which stretches northward to the 82nd de- gree of latitude, experiences under the 60th parallel a more rigorous Climate than Lapland under the 72nd parallel. Tn addition, however, to the cause here assigned by Hum- boldt, it must be borne in mind that the eastern coast of Greenland is skirted for a thousand miles by the cold waters of the Greenland current flowing from the North Pole, while Lapland is warmed by the waters of the Gulf-stream flowing from the south. But if land be situated between the 45th parallel and the equator, it produces, unless it be of great height, exactly the opposite effect; for it then warms the tracts of land or sea that intervene between it and the polar circle. For the sur- face being in this case exposed to the vertical or steeply sloping rays of the sun, absorbs a large quantity of heat, and raises the temperature of the atmosphere which is in contact with it. For this reason, the western parts of the old conti- nent derive warmth from Africa, ‘which, like an immense furnace, distributes its heat to Arabia, to Turkey in Asia, and to Hurope.* The north-eastern extremity of Asia, on the contrary, experiences in the same latitude extreme cold ; for it has the land of Siberia on the north between the 65th and 70th parallel, while to the south it is separated from the equator by the Pacific Ocean. Tn consequence of the more equal temperature of the waters of the ocean, the climate of islands and of coasts differs essen- tially from that of the interior of continents, the more mari- time climates being characterised by mild winters and more temperate summers; for the sea breezes moderate the cold of winter, as well as the heat of summer. When, therefore, we trace round the globe those belts in which the mean * Malte-Brun, Phys. Geol. book xvii. - sf Ff : na ~~ = | i 2 => ll OCStlC( tier COB oe Seer Pz Sua SF & Fe Bae Be ae S Pea SF gse~ FF (a aa — a ZF SF 2~Se S&S masmepaEeBEFLZA AFA AZLZA FE =| = “< = ee ee ee LF ames AF a=. Pa 5 | =] LATITUDE NORTH 7 a ; Oy FAURER HEI SS FSSA ee ESer? K \ CANARIES —K.WN SS ACW E 40 WEST LoNGiTupE O EAST LONGITUD / ce : FAHRENHE NORTH LATITUDE = Ov AVANNY NVaW — ” WICH HAS BEEN COVERED BY THE SEA | (SINCE: THE COMMENCEMENT OF THE | | as op ») = OBSERVATIONS = The Space shaded with ruled lines, es nan Bs cha NaN Area whisk can’ Be proved by Geta haem an! been bie by the Sea, since the earlier part of the stance. ean Be “ not meant es the eres pea aio kall with ruled she wes ee ie maneape above men - d, but that di porti w water in suc- “9 Uidiover ies chatter te a gro See have been |af ber hy Se ai, eae The Space leh wi now dry The. gh has been always Land, furless occupied by pare water Lakes) 51 the earlier — ant of the EOCENE ee Geology Ge ae of some part of this Are [Spain for exeample ) is imper RF Ae rie aad, 7 2S ULL S AVA Cx. XII.] SINCE THE EOCENE PERIOD. 951 though the separated lands be in sight of each other, the pirds and mammalia are quite distinct.* If we reflect on these facts, and consider what a brief space of time the Post-tertiary era constitutes as compared to the whole of the Plocene period, and if we then endeavour to form an idea of the duration of the antecedent Eocene and Miocene epochs by reference to the greater changes in organic life of which they afford evidence, we shall be prepared to find that a map representing the position of the land and sea in the earliest division of the Eocene period, will be wholly un- like the picture which corresponding portions of the globe now present. In the accompanying map (Plate I.) the proofs of submer- gence, during the period alluded to, in all the districts dis- tinguished by ruled lines, are of a most unequivocal character ; for the areas thus indicated are now covered by deposits con- taining the fossil remains of shells and other creatures which could only have lived in salt water. The most ancient part of the period referred to cannot be deemed very remote, con- sidered geologically ; because the deposits of the Paris and London basins, and many other districts belonging to the older Tertiary epoch, are newer than the greater part of the sedimentary rocks, those commonly called Secondary and Primary (Mesozoic and Paleozoic), of which the crust of the globe is composed. Yet, notwithstanding the comparatively recent epoch to which this retrospect is carried, the variations in the distribution of land and sea depicted on the map form only a part of those which must have taken place during the same period. Some approximation has merely been made to an estimate of the amount of sea converted into land in parts of Europe best known to geologists; but we cannot deter- mine how much land has become sea during the same period ; and there have been repeated interchanges of land and water in the same places, of which no account could be taken.T * Wallace, A., Physical Geography of Russia, published by Sir Roderick Malay Archipelago, Journ. of “Roy. » Murchison, M. de Verneuil and Count Geograph. Soc. 1864. Keyserling. M.de Verneuil’s excellent In compiling this map I have map of Spain has also enabled me to availed myself of the government sur- extend the ruled lines over part of that veys of England, France, and Ger- country where before his survey no Many, and of the important map of _ tertiary strata were supposed to exist. 252 CHANGES SINCE THE TERTIARY PERIOD. (Cu. XII. I was anxious, even in the title of this map, to guard the reader against the supposition that it was intended to repre- sent the state of the physical geography of part of Hurope at any one point of time. The difficulty, or rather the impossi- bility, of restoring the geography of the globe as it may have existed at any former period, especially a remote one, consists in this, that we can only point out where part of the sea has been turned into land, and are almost always unable to de- termine what land may have become sea. All maps, there- fore, pretending to represent the geography of remote geo- logical epochs must be to a great extent ideal. The map under consideration is not a restoration of a former state of things, at any particular moment of time, but a synoptical view of a certain amount of one kind of change (the conver- sion of sea into land) known to have been brought about within a given period. The vertical movements to which the land is subject in certain regions, consist of the alternate subsidence and up- rising of the surface; and by such oscillations at successive periods, a great area may have been entirely covered with marine deposits, although the whole may never have been beneath the waters at one time; nay, even though the rela- tive proportion of land and sea may have continued unaltered throughout the whole period. I believe, however, that since the commencement of the Tertiary period, the dry land in the northern hemisphere has been continually on the increase, both because it is now greatly in excess beyond the average proportion which land generally bears to water on the globe, and because a comparison of the Secondary and Tertiary strata affords indications of a passage from the condition of an ocean interspersed with islands to that of a large continent. But supposing it were possible to represent all the vicissi- tudes in the distribution of land and sea that have occurred during the Tertiary period, and to exhibit not only the actual existence of land where there was once sea, but also the ex- tent of surface now submerged which may once have been land, the map would still fail to express all the important revolutions in physical geography which have taken place within the epoch under consideration. For the oscillations b] ij x | | | | | | ANTIQUITY OF EXISTING CONTINENTS, 253 Cu. XII] of level, as was before stated, have not merely been such as to lift up the land from below the water, but in some cases to occasion an additional rise of tracts which had already emerged. Thus the Alps have acquired 4,000, and even in some places more than 10,000 feet of their present altitude since the commencement of the Eocene period; and the Pyrenees have attained their present height, which in Mont Perdu exceeds 11,000 feet, since the deposition of the num- mulitic or Hocene division of the Tertiary series. Some of the Tertiary strata at the base of the chain are only a few hundred feet above the sea, and retain a horizontal position, without partaking in general in the disturbances to which the older series has been subjected ; so that the great barrier between France and Spain was almost entirely upheaved in the interval between the deposition of certain groups of Ter- tiary strata. On the other hand, some mountain-chains may have been lowered during the same lapse of ages, in an equal degree, and shoals have probably been converted into deep abysses, as seems decidedly to have taken place in the Mediterranean. Geologists are now agreed that the limestone and associated strata called nummulitic belong to the Hoéene group ; as these rocks enter into the structure of some of the most lofty and disturbed parts of the Alps, Apennines, Carpathians, Pyrenees, and other mountain-chains, and form many of the elevated lands of Africa and Asia, their position almost implies the ubiquity of the Eocene ocean in regions which are now dry land, not, indeed, by the simultaneous, but by the successive, occupancy of the whole ground by its waters.” Antiquity of existing continents.—It is perfectly consistent with the preceding observations to affirm that our present continents are extremely ancient. They have all of them, it is true, undergone many minor modifications in their form even in post-tertiary times, some parts of them having been submerged and others so much raised, as to have been united with what are now islands lying at some distance from them. But the principal masses of land have continued so long * See Sir R. Murchison’s Paperonthe and my Anniversary Address for 1850, Alps, Quart. Journ. Geol. Soc. vol. v.; — ibid. vol. vi. 254 ANTIQUITY OF EXISTING CONTINENTS. (Cu. XII above water, that each of them is now tenanted by a distinct set of animals and plants. More than this: we find, when we examine the fossil remains of land quadrupeds of Pliocene date proper to each continent, that although they may be of extinct species, they are allied in structure to the living mammalia of the same region. Extinct species of kangaroo, for example, and of other marsupials, preceded the living marsupials on the Australian continent. In like manner, species of elephant and rhinoceros, and of catarrhine mon- keys, of forms no longer in existence, inhabited India in Miocene and Pliocene times, before the living representatives of the same genera and families were in being; while, in the New World, the platyrrhine quadrumana and the sloths, armadillos, and other South American forms belonging to an extinct fauna, flourished in times immediately antecedent to those of the recent mammalia of the same continent. The complete dissimilarity, also, of the marine fauna on the opposite sides of several continents attests the perma- nence of the great barriers of land, which have, from a remote age, prevented the migration of fish, mollusca, and other aquatic tribes from one sea to the other. But the distinctness of these marine provinces does not go back to the Lower Miocene period ; and even when we carry back our retrospect to the Upper Miocene, we find evidence that the mollusca and corals of the Atlantic and Pacific Oceans did not then belong to distinct species as they do now. There must have been up to that time a communication through the isthmus of Panama, as is proved by the study of the corals and marine shells of the West Indian islands.* If we go back still further—to the terrestrial plants and animals of the Hocene period, we find such a mixture of forms now having their nearest living allies in the most distant parts of the globe, that we cannot doubt that the distribution of land and sea bore scarcely any blance to that now established. Continents therefore, although permanent for whole geolo- gical epochs, shift their positions entirely in the course of ages. * See Papers by John Carrick Moore, ey and Dr. Duncan, referred to in ‘ Elements of Geology,’ 6th edition, 1865, p. 271 Cu. XII] FORMER GEOGRAPHICAL CHANGES. O55 The great slowness with which the change is always brought about results from a peculiarity in the external configuration of the earth’s crust, which I shall point out in the sequel of this chapter (see p. 265). Both in the eastern and western hemispheres north of the . equator, when we carry our retrospect beyond the limits of the tertiary rocks, and pass on to the antecedent cretaceous formations, we find abundant proofs of an open sea in regions which are now continental. . In the oldest part of this period in the south of England, we find in the Wealden strata the memorials of the delta of a large river, implying a contour of land and sea which has no reconcilable relation to existing geographical conditions ; and it is worthy of note that, although the foundations of this delta sank during the accumulation of the fluviatile strata as much as 1,000 or sometimes 1,500 ft., yet there continued to be land in the neighbourhood in the south-east of England ; which can only be explained by supposing that an upward movement was taking place in the vicinity of a downward one, or that parts of the surface were moving slowly in two opposite directions. The frequent unconformability of successive strata of different ages—those standing next in succession having so often been deposited horizontally on the group which im- mediately preceded, or, to speak more correctly, which in our defective chain of known records stands, at present, next in consecutive order—is a proof that if we had a series of maps, in which a restoration of the physical geography of thirty or more periods were depicted, they would bear no more resemblance to each other or to the actual position of land and sea, than does the map of one hemisphere at present to that of the other. The height to which ammonites, shells, and corals have been traced in the Alps, Andes, and Himalaya is sufficient to show that the materials of all those chains were elaborated under water, and some of them in seas of no slight depth. Beds of coal, in the ancient carboniferous formation, were derived, as we have seen in the last chapter, from plants which grew on low swampy lands covered with forests. The sands and shales which over- and under-lie them must have 256 ANCIENT GEOGRAPHICAL CHANGES, {Cu XIt. been formed at the termination of large hydrographical basins, each drained by a great river and its tributaries; and the accumulation of sediment bears testimony to contempo- raneous denudation on a large scale, and, consequently, to a area of land, probably containing within it one or more mountain-chains. Tn the case of the great Ohio or Appalachian coal-field, the largest in the world, it seems clear that the uplands drained by one or more great rivers were chiefly to the eastward, or occupied a space now filled by part of the Atlantic Ocean, for the mechanical deposits of mud and sand increase greatly in thickness and coarseness of material as we approach the ‘eastern borders of the coal-field, or the south-east flanks of the Alleghany Mountains, near Philadelphia—in other words, as we get nearer to the Atlantic. In that region numerous beds of pebbles, often of the size of a hen’s egg, are seen to alternate with beds of pure coal. It has also been observed, in reference not only to the Carboniferous but to the antecedent Devonian and Silurian rocks of North America, that all the mechanical deposits, as we travel from the Atlantic border to the Mississippi, diminish constantly in thickness, while the limestones or open-sea deposits, with corals and encrinites, increase and replace the others. . But the American coal-fields are all comprised within the 30th and 50th degrees of north latitude; and there is no reason to presume that the lands at the borders of which they originated ever penetrated so far, or in such masses, into the colder and arctic regions, as to generate a cold climate. One of the members of the Carboniferous group, the moun- tain limestone, was of marine origin, and its occupancy of large areas in Europe and the United States, and in parts of North America bordering the Arctic Sea, makes it quite conceivable that there may have been such a condition of things at the period of the coal as might give rise to a general warmth and uniformity of climate throughout the globe. The Silurian strata now constituting parts of many upland or mountainous regions in Hurope and America were formed for the most part in deep seas far from land, which may : Cu. XIL.] UNEQUAL DISTRIBUTION OF LAND AND SEA. 257 account for their being almost entirely destitute of the remains of terrestrial plants. Present unequal distribution of land and sea.— Without dwelling longer on the proofs with which geology supplies us of former changes in physical geography, it is not too much to say that every spot which is now dry land has been sea at -gome former period, and every part of the space now covered py the deepest ocean has been land. 'The present distribution of land and water encourages us to believe that almost every conceivable transformation in the external form of the earth’s crust may have been gone through. In one epoch the land may have been chiefly equatorial, in another for the most part polar and circumpolar. At one period most of it may have been north of the line, in another south of it; or at one time all in the west, at another the whole of it in the east. In illustration of this point, it may be well to state that there is now just twice as much land in the eastern as there is in the western hemisphere ; and even assuming the existence of an antarctic continent, more than twice as much land north of the equator as south of it. But what is most singular, as showing the capricious distribution of the land in the present state of the earth’s crust, we find it possible so to divide the globe into two equal parts, that one hemi- sphere shall contain as much land as water, while the other is so oceanic that the sea is to the land very nearly as 8 to 1.* This is shown by projecting the hemispheres on the plane of the horizon of a point in lat. 52° N. and in long. 6° W. of Greenwich. The point alluded to is situated in St. George’s Channel, about midway between Pembroke and Wexford, and the eye of the observer is supposed to be so placed above it as to see from thence one half of the globe. In such a position he would behold at one view the greatest possible quantity of land, or, if transferred to the opposite or antipodal point, the greatest possible quantity of water. 4n previous editions I used, in illustration of the same sub- ject, a map projected for me by the late Mr. James Gardner on the horizon of London, for he regarded that metropolis The exact proportion of land tosea, 1:106 in the Land eee and 1 as calculated by Mr. Saunders, is 1 to to 7:988 in the Water Hemisphere VOL. I. 258 UNEQUAL DISTRIBUTION OF LAND AND SEA. (Cu. XII. D THE GLOBE. OF 1 } THE SURFACE ON Fig. 11. Here a point in St. George’s Channel, midway between Pembroke and Wexford, is taken as a centre, and we behold the greatest quantity of water existing in OF LAND AND WATER PRESENT UNEQUAL DISTRIBUTION THE MAP SHOWING T: aueisphert x 1 one h = Fig. 12. Cu. XII.] UNEQUAL DISTRIDULION OF LAND AND SEA. S59 as the centre of the Land hemisphere. The maps now pre- sented to the reader have been executed by Mr. Trelawny Saunders, who has so divided the globe as to add to the Land hemisphere part of 8. America, including a portion of the Peruvian coast, while an equivalent area of the China Sea is transferred to the Water hemisphere. Intimately connected with the excess of land in the one hemisphere as compared to that in the other is the fact that, even allowing for the antarc- tic continent as expressed in the map, only one-thirteenth part of the dry land has any land diametrically opposite to it. Thus, in fig. 12 the land shaded black between the China Sea and Lake Baikal answers to that portion of S. America and Tierra del Fuego which is antipodal to it. Farther north, a part of the continent of Asia, extending along the arctic sea, as well as a large tract of Greenland and other arctic lands shaded in the same manner, are antipodal to the antarctic continent. The dark spots in South America represent tracts antipodal to Java, Borneo, the Celebes and Philippines, a part of Sumatra, and the Malay peninsula. The specks in Africa bear a similar relation to the islands in the Pacific Ocean, and the dark patches in Spain and Morocco mark those countries as partially antipodal to New Zealand. The limits of the supposed antarctic continent have been drawn with reference to the known position of Victoria, Wilkes’, Enderby’s, and Graham’s Lands, and the points where Ross, Weddell, and other navigators were stopped by the ice ; but in order not to exaggerate the proportion of dry land in ) the unexplored area I have assumed one-eighth of it to be sea. : This reduction has been made by extending the basin of the : ocean somewhat nearer the pole than the points to which | our navigators have yet penetrated, both between Graham’s and Enderby’s Lands and between the latter and Termina- tion Land, in the former of which regions the ships were usually stopped by pack-ice before reaching the 70th, and in 7 the other the 65th degree of latitude. On the other hand, I | have thought it safer not to represent all the unexplored | area at the N. Pole as sea; and have therefore given one- eighth of it as land, which has been done by introducing Several supposed islands in the open sea said to exist off the y) 260 GEOGRAPHICAL CHANGES CAUSING FLUCTUATIONS [Cu. XII. Russian coast, and, according to Morton, off the N.W. of Greenland. Former geographical changes which may have caused the fluctuations in climate revealed to us by geology.—Having now shown the reader that there have been endless changes in the form of the earth’s crust in geological times, whereby the position as well as the height and depth of the land and sea has been made to vary incessantly, and that on these geo- graphical conditions the temperature of the atmosphere and of the ocean in any given region and at any given period must mainly depend, I shall next proceed to speculate on the nature of the changes which, if assumed, might account for the leading facts revealed to us by geology as explained in the last two chapters. Tn order that our speculations may be confined within the strict limits of analogy, I shall assume, 1st, That the propor- tion of dry land to sea continues always the same. 2ndly, That the volume of the land rising above the level of the sea is a constant quantity ; and not only that its mean, but that its extreme height, is liable only to trifling variations. 3rdly, That on the whole and in spite of local changes, both the mean and extreme depth of the sea are invariable; and 4thly, That the grouping together of the land in continents is a necessary part of the economy of nature. I think it consis- tent with due caution to make this last assumption, because it is possible that the laws which govern the subterranean forces, and which act simultaneously along certain lines, cannot but produce, at every epoch, continuous mountain- chains; so that the subdivision of the whole land into innu- merable islands may be precluded. If it be objected, that the maximum of elevation of land and. depth of sea are probably not constant, nor the gather- ing together of all the land in certain parts, nor even perhaps the relative extent of land and water, I reply, that the argu- ments about to be adduced will be strengthened if, in these peculiarities of the surface, there be considerable deviations from the present type. If, for example, all other circum- stances being the same, the land is at one time more divided into islands than at another, a greater uniformity of climate Cu. XIT.] IN CLIMATE REVEALED BY GEOLOGY. 261 might be produced, the mean temperature remaining un- altered; or if, at another era, there were mountains higher than the Himalaya, these, more especially when placed in high latitudes, would cause a greater excess of cold. Or, if we suppose that at certain periods no chain of hills in the world rose beyond the height of 10,000 feet, a greater heat might then have prevailed than is compatible with the exist- ence of mountains thrice that elevation. Since I first proposed in 1830 to account for the more genial climates of former times, by showing that there is now an excess of land in polar regions, Mr. Hopkins has made some important calculations to prove that, by reasoning on data supplied by the isothermal maps of Dove, we may infer that a great alteration in climate would be brought about in the northern hemisphere by what every geologist must regard as slight alterations in geography. If, said he, we assume; Ist, the diversion of the Gulf-stream from its present northerly course ; 2ndly, the depression of the existing land of Northern and Western Europe to the amount of no more than 500 feet; and 8rdly, a cold current from the North, sweeping over the submerged area, the effect would be, that both on Snowdon and the lower mountains of the West of Ireland the snow-line would descend to within 1,000 feet of the sea-level, and glaciers reach the sea.* Now everyone who is aware of the rising and sinking of land, of which we have proofs since the present species of animals and plants were in existence, or since the commencement of the Glacial epoch, will be prepared to concede that, without violating probability, we may imagine far more important changes to have occurred since the older Pliocene period than those above suggested. Even if we admit that the Glacial period began as far back as the close of the Newer Pliocene era, when 5 in 100 of the mollusca were of different species from those now living, we might still fairly speculate on the lapse of a period more than ten times as long since the older Pliocene deposits were formed, for in these more than half the shells belong to extinct species. * Quarterly Journ. Geol. Soc, 1882. 962 MAP REPRESENTING NORTH AND SOUTH (Cu. XII. We might reckon on a tenfold greater amount of geographi- cal change as having occurred in an interval sufficient to allow of fluctuations in organic life on so much grander a scale. Hven if changes in the position of land and sea are brought about as slowly as those now in progress, so as to be quite insensible to ordinary observation, we may still be prepared to believe that when we go back to the older Pliocene period, land between the arctic and antarctic circles and the pole may have been so much less in quantity as compared to what it now is, that instead of being equal in area to the a, it may only have been in the proportion of about 1 to But such a reduction of the quantity of land in high latitudes would be accompanied by an equivalent increase of land in temperate or tropical regions, unless we suppose the general surface of the earth’s crust to have been less irregular than it is now—an hypothesis which we are not entitled to make. Consequently, whatever is lost to polar areas, where land gives rise to an augmentation of cold, would be gained in those lower latitudes, where it causes an increase of warmth. Therefore a more normal state of ceography, or one in which the polar, temperate, and equa- torial regions would each contain more nearly than they do now a proportion of one part land to two and a half parts sea, would bring back those genial climates which generally obtained in the past history of the world. The accompanying map (fig. 13) may help the reader to imagine what would be the -amount of change, if the geography of the globe were altered from its present ex- ceptional state to what I consider a more normal condition of things. In this ideal map the excess of land is removed from the arctic and antarctic zones, and transferred to the tropical zone, which last, after this accession, contains only its normal quantity of land, or a proportion to the water of about 1 to 24. The land thus shifted from the poles has not been placed at random in the tropics, but has been made to fill those oceanic spaces which are supposed to have been above water in Post-tertiary, or at least, in Newer Pliocene times, in accordance with Darwin’s map of coral atolls. It may be objected that during such an amount of no 7m >) boli ~ Migr. 12. Cu. XID] Fig. 13. re Soom er POLAR LANDS IN NORMAL QUANTITY. 268 21 sea; the present excess being a On 2 3 Be 8 s ws pees h polar lands are yeduced to a norma areas of modern subsidence between the Tropies. shifted to ideal Map, in which the north and sout 264 NORMAL QUANTITY OF LAND. (Cu. XI, transposition of sea and land in the polar and equatorial zones, we ought to expect a corresponding amount of change in the outline of continents and islands in other regions. This I fully admit; but those changes might take place without in the least degree affecting the general climate of the globe or the average temperature of the atmosphere. So long as the conversion of sea into land or land into sea does not cause any alteration in the proportions of land to water in the same zones, a vast amount of fluctuation may take place without those zones being rendered warmer or colder. ven if the land and sea in the eastern and western hemispheres were to change places, this need not affect the general temperature of the earth’s surface, although the transfer of an equal volume of land from the torrid zone to the arctic or antarctic regions would cause a prodigious refrigeration in all latitudes. I have therefore left the land and sea as they now are, that those variations in geography which would affect climate may be more easily recognised. In this same map it will be seen that the diminution of arctic and antarctic land would enable oceanic currents to flow more freely from high to low, and from low to high latitudes, so that there might always be much open sea at the poles. Mr. Darwin, in one of his interesting speculations on the migration of species in pre-glacial times, has endeavoured to explain the number of plants and animals common to the Old and New World, by supposing that during an earlier and warmer period such as the older Pliocene, there was a con- tinuity of land in high latitudes,* as, for example, between North America and North-eastern Asia. It would have been easy for me to represent such a state of things in the map without leaving more than a normal proportion of land to sea within the limits of the arctic circle. I may also ob- serve that the migrations alluded to might have been effected from east to west and from west to east, between the latitudes AMO .: Aid n and 65° N., if at successive periods the different parts of 1ese continents were each in their turn connected. The tl e hypothesis alluded to does not require that there should have * Origi t in of Species, 4th edition, chap. xi. Ou. XIL] GREAT DEPTH OF SEA. 265 been an unbroken continuity of land at one and the same me. : Great depth of the sea as compared to the mean height of the land connected with the slowness of climatal changes.—I shal conclude this chapter by observing that if at any former period the climate of the globe was much warmer or colder than it 1s now, it would have a tendency to retain that higher or lower temperature for a succession of geclogical epochs. That tendency would usually be in favour of warmer climates, because these would be consistent with a normal state of geography ; but, if once abnormal conditions like the present prevailed, they would be persistent for an indefinite lapse of ages. The slowness of climatal change here alluded to would arise from the great depth of the sea as compared to the height of the land, and the consequent lapse of time re- quired to alter the position of continents and great oceanic basins. To one who contemplates the vast amount of geographical change which has occurred in Post-tertiary, and still more in Pliocene and Miocene times, it might at first sight appear that in the course of such a period as might corre- spond with the disappearance of one set of organic beings and the coming in of another, there would be a complete revolution in the outward form of the earth’s crust. But such an opinion would not be in harmony with the facts which have come to our knowledge of late years in regard. to the average height of the continents as contrasted with the enormous depth of the sea, both as inferred theoretically from observations on the tidal wave, and proved practically by deep sea soundings. The mean height of the land is ouly 1,000 feet, the depth of the sea 15,000 feet. The effect, therefore, of vertical movements, equalling 1,000 feet in both directions, upward and downward, is to cause a vast transposition of land and sea in those areas which are now continental, and adjoining to which there is much sea not exceeding 1,000 féet in depth. But movements of equal amount would have no tendency to produce a sen- sible alteration in the Atlantic or Pacific oceans, or to cause the oceanic and continental areas to change places. De- 266 MAPS SHOWING EXTREME OF HEAT [Cu. XII. pressions of 1,000 feet would submerge large areas of the existing land, but fifteen times as much movement would be required to convert such land into an ocean of average depth, Maps showing the position of Lanp and Sra which might avai the Extremes of Hzar and Corp in the Climates of the GuLoz Fig. 14. Extreme of Cold. Orsi These a are intended to show that continents and islands having the same ae ape and relative dimensions as those now existing, might be placed so as to occupy either the equatorial or polar regions. fig. 14, 5 carcely any of the land extends from the Equator towards the poles be vend the 30th parallel of latitude; and in fig. 15, a very small proportion of it extends from the poles towards the Equator beyond the 40th parallel of latitude. éy XI] AND EXTREME OF COLD. 267 or to cause an ocean three miles deep to replace any one of the existing continents. Tt is quite essential to bear in mind this remarkable feature in the physical geography of the earth, when we are speculating on the cause of the per- manence of a particular climate, or distribution of heat or cold during a series of epochs. According to the doctrine of chances, it would not often happen that even one of the polar regions would contain so much land as both of them do at present, but ereat indeed would be the chances against the simultaneous preponderance of such an abnormal quantity of land, both in arctic and antarctic latitudes. The annexed maps will enable the reader to understand the manner in which land, having the same proportion to the sea as it now has, might be collected together in equatorial or polar regions. Such extremes may never have occurred, but we may safely conclude that there must sometimes have been an approximation to them in the course of those ages to which our geological records refer. A glance at these maps will make it evident that in the present state of the globe we are much nearer to the winter than to the summer of the ‘Annus magnus,’ or great cycle of terrestrial climate. CU CHAPTER XIII. VICISSITUDES IN CLIMATE HOW FAR INFLUENCED BY ASTRONOMICAL CHANGES. THE PRECESSION OF THE EQUINOXES, AND VARIATIONS IN THE EXCENTRICITY OF THE EARTH'S ORBIT CONSIDERED AS AFFECTING CLIMATE.—UNDER WHAT CONDITIONS EXTREME EXCENTRICITY MAY EXAGGERATE COLD.—MEASUREMENT OF HEAT, TEMPERATURE OF SPACE.—CLIMATES OF SUCCESSIVE PHASES OF EH OBLIQUITY OF THE ECLIPTIC.—RADIATION OF HEAT IMPEDED BY A COVERING OF SNOW.—QUANTITY OF POLAR ICE AND I TS INFLUENCE IN ALTERING THE LEVEL OF THE OCEAN.—MIGRATIONS OF THE ERAS OF MAXIMUM EXCENTRICITY DATES OF THE NEOLITHIC AND PALEO- OF THE INTENSITY OF GLACIAL COLD.—DURATION OF THE GLACIAL PERIOD AS COMPARED TO SUCCESSIVE TE RTIARY, SECONDARY, AND PRIMARY EPOCHS.—SUPPOSED VARIATIONS IN THE TEMPERATURE OF SPACE SOLAR MAGNETIC PERIODS AND VARIABLE SPLENDOUR OF THE STARS.—SUPPOSED GRADUAL DIMINUTION OF THE EARTH’S PRIMITIVE HEAT.—SUPPOSED CHANGE IN THE POSITION OF THE AXIS OF THE EARTH’S CRUST. The precession of the equinoxes and variations in the excen- tricity of the earth’s orbit considered as affecting climate.—In the last chapter we were chiefly occupied in considering how far changes in physical geography or in the position of land and sea may account for those variations of climate to which geology bears testimony. I endeavoured to show that this class of causes must alw rays have exerted a dominant influence ; and we may now consider how far those variations in the relative position of our planet to the other heavenly bodies which astrono1 my reveals to us, may have affected climate. In other words, to what extent may the precession of the equinoxes, the revolution of the apsides, and the centricity of the earth’s orbit, have co-operated with geo- ~~ yrs graphical conditions in bringing about fluctuations of tempe- pave rature in the habitable parts of the globe in former ages. Cu. XIII] ASTRONOMICAL CAUSES AFFECTING CLIMATE — 269 Sir John Herschel, in 1832,* entertained the question whether there are any astronomical causes which might offer a possible explanation of the difference between the actual temperature of the earth’s surface and the climates which appear formerly to have prevailed. ‘ Geometers,’ he observed, ‘had demonstrated the absolute invariability of the earth’s mean distance from the sun, whence it would seem to follow that the mean annual supply of light and heat would be alike invariable. This, however, is not exactly true: the total quantity of heat received in one revolution is inversely proportional to the minor axis ;” still, as the extreme amount of difference in the quantity of heat annually received, owing to such change in the minor axis, can never by possibility ex- ceed the whole supply ina ratio of more than 1,003 to 1,009, it may, he says, be neglected in our geological speculations. But there is another way in which changes in the excen- tricity of the orbit affect climate. Climate depends not merely on the absolute amount of heat, but on the manner in which it is distributed through different parts of the year, especially in the polar and circumpolar zones of the earth. At present the earth’s orbit is becoming every year more circular, but only at a very slow and somewhat irregular rate, and it will become in 23,980 years after a.p. 1800 nearly as circular as it can ever be, or will approach a minimum excentricity, after which it will again increase at the same slow rate. These perturbations are caused by the attraction of the nearest and largest planets, Jupiter and Saturn playing the principal part, and the other planets, especially Venus and Mars, also exerting a sensible influence. It has long been known that the deviation of the orbit from a circle could never exceed certain limits, and these limits were very nearly defined by Lagrange towards the end of the last century, and more exactly by Leverrier in 1839. The ex- treme range of excentricity as expressed by the difference in distance of the earth from the sun in aphelion and peri- helion amounts in round numbers to a little more than fourteen millions of miles, the minimum but slightly exceed- ing halfa million. In other words, recent observation having * Trans. Geol. Soc., 2nd series, vol. iii. 270 EFFECTS OF EXTREME EXCENTRICITY [Ca. XIII, determined the mean distance of the earth from the sun to be 91,400,000 miles, the excentricity in the one case, or when it is sagan amounts to =4;, and in the other, or when it is least, to =1, of the whole. Whatever be the ellipticity of the earth’s orbit, says Sir J. Herschel, the two hemispheres must receive equal absolute Samui nas of light and heat per annum, the proximity of the sun in perigee, or its distance in apogee, exactly compensating the effect of its swifter or slower motion.* But the same writer, in 1858, alluding to some speculations of Reynauld, speaks of the marked effects on climate which great vari- ations in excentricity might produce, causing the charac- ters of the seasons in the two hemispheres to be strongly contrasted. ‘ In the northern (assuming the position of the line of the apsides to be as now) we should have a short but very mild winter, with a long but very cool summer—i.e., an approach to perpetual spring; while the southern hemisphere would be inconvenienced, and might be rendered uninhabit- able by the fierce extremes caused by concentrating half the annual supply of heat into a summer of very short duration, and spreading the other half over a long dreary winter, sharpened to an intolerable intensity of frost when at its climax, by the much greater remoteness of the sun;’ t and he goes on to observe, that, in consequence of the precession of the equinoxes, combined with the secular movement of the aphelion, the state of the northern and southern hemi- spheres here alluded to, would in the course of about 11,000 years be reversed, and. such alternations of climate must in the immense periods of the past which the geologist con- templates, have happened not once only, but thousands of times ; and ‘it is not impossible,’ he adds, ‘ that some of the indications of widely different climates in former times may be referable, in part at least, to this cause.’ * This follows, observes Herschel, be divided into two portions by a line from a very simple theorem, which may drawn in any direction through the sun’s be thus stated :—‘The amount of heat centre, the heat received in describing received by the earth from the sun 1e two unequal segments of the ellipse while describing any per of its orbit, is so produced “a be equal. Geol. Trans. proportional to the nd vol. iii. part ii. p. 298; second series. the sun’s centre.’ on eas if pt parr ik Harsshal’s oon Art. 368 ¢ ot ea Cu. XIII.] ON THE CLIMATE OF THE EARTH. 271 Under what conditions extreme excentricity may exaggerate cold.—Mr. James Croll, in an able memoir published in 1864, ‘On the Physical Cause of the Change of Climates during Geological Epochs,’ * made an important suggestion, explanatory of the manner in which a maximum excentri- city would tend to exaggerate the cold in that hemisphere in which winter cccurred in aphelion. The difference, he observes, (in conformity with a remark of Sir J. Herschel +) of the sun’s heat, whether in winter or summer, as con- trasted with that which obtains in those same seasons, in the present state of the ellipticity of the orbit, would not be expressed merely by the differences in distance, before alluded to, namely, 144 millions of miles for the extreme, and 8 millions for the present excentricity, but it would amount to no less than one-fifth of the entire heat received from the sun, because that heat would vary inversely as the squares of the distance. In consequence, therefore, of the lowering of the temperature by one-fifth in that hemi- sphere in which winter occurs when the earth is farthest from the sun, all the moisture precipitated from the air in high latitudes would fall in the form of snow instead of rain; and the heat of summer, although one-fifth greater than what we now experience, would be insufficient to re- move the accumulation’ of winter snow. The direct power of the sun’s ‘rays would be greatly intensified when the sky was cloudless, but the constant melting of so much ice would, in a great measure, neutralise their force, by giving rise to fogs and an overcast sky. The rain of summer, he says, would not melt one-eighth part of the snow in winter, for it takes nearly eight tons of water at 50° F. to melt one ton of snow at 32° F. Mr. Croll contends, therefore, that while one hemisphere during this maximum excentricity would be enduring the extreme cold of a lengthened winter, and having its summer heat chilled by the melting of ice, the other hemisphere would be enjoying a perpetual spring ; the polar winter occurring in perihelion, when the tempera- ture was one-fifth greater than at present, and there being no accumulation of snow beyond what the sun’s rays could * Croll, Phil. Mag., August 1864. { Herschel’s Astronomy, Art. 368 ¢. 272 EXCENTRICITY CAUSING EXTREME COLD. [CH XIE dissipate during the course of the year. Hence he concludes that such climates as we have described at page 224, as pre- vailing in the Carboniferous epoch, when there was great warmth and moisture in the air throughout temperate and arctic latitudes, would be experienced during that phase of precession (the excentricity being very large), when one hemisphere—the northern, for example—had its winter in perihelion, there being then an equality of seasons, or that perpetual spring alluded to by Herschel. Mr. Croll has also endeavoured to show that the vast accumulation of ice which would alternately take place at each pole during those thousands of years for which winter would occur when the planet was farthest from the sun, would so derange the earth’s centre of gravity as to draw the ocean towards that pole and cause the submergence of part of the land. M. Adhémar, in 1843, had already endeavoured to account for certain geological phenomena by a coincidence of the winter solstice with aphelion, but without connecting them, as Mr. Croll has done, with that greater excentricity of the earth’s orbit, which must occasionally in the course of ages vastly exaggerate the effects alluded to. Although the deficiency of our data is such that we cannot yet decide to what extent this excess of ice at certain periods would act as a disturbing cause, yet as there can be no doubt that it must have given rise at some points to a sensible dif- ference in the ocean’s level, we are greatly indebted to those scientific writers who have called attention to a vera causa hitherto neglected. To this subject I shall again allude in the sequel. Mr. Croll, in the memoir alluded to, ascribes little or no influence to abnormal geographical conditions, such as, ac- cording to the principles explained in the last chapter, I should consider indispensable in combination with a large excentricity for the production of great cold. I also differ from him in the opinion that a large excentricity, even as- suming that it might give rise, as he suggests, to a storing up of ice in high latitudes, or to a glacial period, would also bring about, in the same hemisphere in the opposite phases of precession, a period of perpetual spring. On the contrary, ee Cu, XIIT.] CLIMATAL EFFECTS OF EXCENTRICITY. 273 I conceive that, although under favourable geographical circumstances the greatest accumulation of snow would always take place at that pole where midwinter happened to occur in aphelion, there must be a continual excess of cold in both hemispheres, so long as the large excentricity lasts throughout all the phases to which one or more cycles of precession and the revolution of the apsides would give rise. I also think it probable that be the amount of excentricity great or small, there would, so often as the distribution of land and sea is not exceptional, or whenever a normal condition of things obtains as expressed in the ideal map, fig. 13, p- 263, be no increase of cold from year to year. Moreover, it appears to me almost certain, that whenever a deep ocean prevailed at both poles, there would be, instead of a storing up of ice in polar regions, no snow whatever on the globe; and during extreme excentricity the minor axis of the ellipse being shortened, the total quantity of heat received from the sun would be slightly in excess of the present, namely, by thir- teen hours of sunshine every year, as computed by Meech.* This slight difference may well be regarded as too insigni- ficant to affect climate, but we must not forget in our geolo- gical speculations that if it could make itself felt, it would be in an opposite direction to that which would bring about glacial periods. It was stated at the close of the last chapter, that the marked prevalence of warmer climates in temperate and arctic latitudes in former geological epochs, is what we might have anticipated in consequence of the larger extent of sea at the poles, and I have explained how slow must be the conversion of the basins of deep seas into continents (p. 265). Nevertheless, as in the course of millions of ages, it must sometimes have happened that there was an abnormal quantity of land in high latitudes, and as this geographical state of things when once established would endure long enough for every phase of excentricity and precession to be run through, we ought to find proofs of cold or glacial in- terludes in the midst of a preponderating number of warmer am Intensity of the Sun’s Heat and Light. Smithsonian Contributions, VOL. I. 1. O74 CLIMATE OF THE EARTH AFFECTED BY (Cu. XII. periods, and recent observation seems to favour the reality of such events. : In order to explain the extent to which I conceive that astronomical conditions may sometimes exaggerate the in- tensity of cold, I shall begin by speaking of the movement called the precession of the equinoxes, which is well known to be due to the attraction of the sun and moon on the pro- tuberant matter at the earth’s equator (for if the earth were a perfect sphere there would be no precession); the moon exerting the greatest disturbing force, notwithstanding its small mass, in consequence of its greater proximity. By virtue of this movement, the different seasons of the northern and southern hemisphere are made successively to coincide with all the points through which the earth passes in its orbit, and consequently at all distances from the sun, con- sistently with a given state of excentricity. Winter, for example, spring, autumn, and summer, occur each of them in their turn, both north and south of the line at periods when the earth is most distant from and nearest to the sun, as well as at every one of the intermediate dis- tances. This great cycle of change would be gone through in 25,868 years were it not shortened by being combined with another movement called the revolution of the apsides. This last consists of a gradual change in the direction of the major axis of the earth’s orbit due to the same disturbing forces which cause the ellipticity of the orbit to vary, namely, the attraction of the larger and nearer planets. The result of the combination of these two causes of perturbation 1s, that in 21,000 years, the seasons will have made a complete revolution so as again to coincide with the same point in the orbit as at present, and in half that period, or about 10,500 years, the present astronomical state of things will be reversed, so that winter will occur in our hemisphere in aphelion, and at the south pole in perihelion. If the orbit were circular and our planet always equidistant from the sun, the four seasons, so long as geog raphical cir- cumstances remained constant, would always hold the same relation to one another in respect to temperature in every phase of precession. And even now this uniformity may be FI ce ercceesionein sa i ee oe Cx. XTII.] THE PRECESSION OF THE EQUINOXES. 975 said to hold true during vast periods, so slow are the changes in the excentricity of the orbit as compared to those of pre- cession, two or more cycles of the latter movement being usually run through while the excentricity remains essentially the same. This is a point of great geological importance when we are considering to which of three causes fluctuations in climate at successive epochs may have been mainly due; namely, whether to precession, or to variations in excentricity, or to changes in the geography of the globe. To a certain extent all these three causes must combine to produce the climate of any given period. Thus, for example, at present it may be stated, first, that the arctic and antarctic regions, from the poles to the 60th parallels of latitude, are in an ex- ceptional state in regard to the proportion of land to sea which they contain, and that there is consequently a smaller proportion of land in equatorial regions where its presence would augment the heat. Hence the existing geo- graphical conditions favour less genial climates in polar and temperate latitudes than those which have usually prevailed when the condition of things was less abnormal. Secondly, the present excentricity of our orbit, though moderate in degree, causes the earth to receive more heat when it is nearer, and less when it is farther from the sun; and Thirdly, in the northern hemisphere, in the present state of precession, winter occurring in perihelion is rendered milder and shorter than it would otherwise be. The present excentricity of the earth’s orbit amounts, as before stated, p. 271, to no more than a million and a half of miles in opposite directions from its mean distance from the sun, which is ninety-one millions. A good illustration is af- forded of the slight influence on climate of this moderate ex- centricity as compared to that of geographical conditions, by the result of Dove’s observations on the mean temperature of the whole surface of the globe in perihelion as contrasted with its temperature in aphelion. The difference of distance from the sun at these two periods is no less than ;1,th of the mean distance; the planet therefore ought to be colder at the one time and hotter at the other, not merely by ;1,th of the heat tee 76 ' CLIMATE OF THE EARTH AFFECTED [Cx. XII, received from the sun but by 35th, because the heat varies in- versely as the squares of the distance. Yet, as if in violation of this law, when the temperatures of all places north and south of the line are reduced to an average, it is found that the surface of the whole planet is actually warmer in June than in December, i.e., In aphelion than in perihelion. This result, which in an astronomical point of view appears so paradoxical, is explained in a satisfactory manner when we take into con- sideration the great extent of land which exists between the equator and the 50th degree of north latitude, and which is exposed to the sun’s rays during a long summer, whereas the extent of ocean in corresponding latitudes in the southern hemisphere prevents any similar generation of heat during summer, notwithstanding that here, according to Herschel’s estimate, the power of the sun is greater by 23° F. when the planet is in perihelion. ‘ The effect of land,’ says Herschel, ‘under sunshine is to throw heat into the general atmo- sphere, and so distribute it by the carrying power of the air over the whole earth. Water is much less effective in this respect, the heat penetrating its depths and being there absorbed, so that the surface never acquires a very elevated temperature, even under the equator.’ * The present effect, therefore, of the excentricity of the orbit on climate is so subordinate to that of the position of the land, that it is not only nullified by it, but the result is exactly the converse of what we might have expected. Another illustration of the counteracting effect of geo- eraphical causes is afforded by the extreme climates of Canada and other parts of North America, as well as of cer- tain parts of Siberia and China, as contrasted with the more equable climates of the southern hemisphere. A very dif- ferent result might have been looked for if the ascendancy of astronomical causes were complete; for in that hemisphere where winter coincides with the greatest and summer with the least distance from the sun, the seasons would have been most contrasted were it not that the preponderance of sea as compared to land produces an equable or what is called an ‘insular’ climate. * Herschel’s Astronomy, 1864, p. 236, art. 376. Cu. XUI.| BY GEOGRAPHICAL CAUSES. ORT The fact that the cold is now greater throu chout a large part of the southern hemisphere would seem at first sight almost to demonstrate the truth of the theory that the coincidence of the winter solstice with aphelion exerts a powerful refri- eerating effect. But the difference of about 10° F. in tem- perate latitudes in the southern hemisphere, is shown by Dove’s tables to be due to a deficiency of land, which is in excess in corresponding latitudes of the northern hemisphere. Without denying that the astronomical cause alluded to must exercise some influence, it is obviously insignificant as contrasted with the power of geographical conditions. Sir John Herschel, indeed, computes on theoretical grounds, that there ought to be a difference of 93° F. when two places are compared at the same season and in the same latitudes on opposite sides of the equator; that is to say, the summer coinciding with perihelion ought to have a temperature of 112° higher, and the winter in aphelion a temperature lower by the same amount, than the same seasons in the opposite hemisphere where these astronomical conditions are reversed. The results of observation are not in harmony with this theory, the difference really indicated by the thermometer being only half that which is required by theory. Yet there are some limited areas where, according to Herschel, the excentricity makes itself felt. The heat, he says, in the interior of Aus- tralia is greater than in the deserts of North Africa in corresponding latitudes; and he has himself observed the temperature of the surface soil in South Africa to reach 159° F., which is higher than it ever rises in our hemisphere where summer does not coincide with perihelion.* Unfor- tunately, the period of astronomical and meteorological ob- servation is too short to enable us to calculate the changes of temperature to which precession gives rise under the present conditions of excentricity. . émar, in a work entitled ‘ Les Révolutions de la Mer,’ published in 1840, suggested that a sensible effect has already resulted from the deviation which has occurred since the year 1248, of the position of the perihelion from the time of the winter solstice in the north. By this movement the * Herschel’s Astronomy, 1864, art. 369, noze. 978 - COMPARATIVE HEAT OF THE SUN [Cu. XII. nearest approach to the sun now occurs eleven days after the shortest day. M. Venetz had previously pointed out as an historical fact, that the Swiss glaciers were greater than they are now before the 10th century, and that then, after retreating for four centuries, they advanced again and have been slowly reacquiring their former dimensions. In other words, at that period when the sun was nearest the earth in midwinter, or for two centuries before and two after 1248, there was the greatest melting of ice in the northern hemisphere. It may be questioned whether this slight astronomical change, which could hardly produce more than a difference of half a degree Fahrenheit between the cold of the present winter and that of 1248, would be appreciable in the course of six hundred years; but the observation may help the reader to understand in what direction the precession of the equinoxes, if capable of producing a sensible change, would now be affecting climate. Measurement of heat—Temperature of space.—But it will be asked, how does the physicist arrive at the determinate quan- tity, 23° Fahr., by which, as above asserted on theoretic grounds, the two hemispheres at present ought to differ from one another? For though it is known that the sun’s radiation. varies as the inverse square of the distances, this law would not conduct us to the absolute quantity, unless we also knew from what starting-point the heat is to be measured. The degrees of our thermometers are arbitrary quantities, and measured from arbitrary points. The question is, how many of the degrees indicated by one of these scales (say Fahrenheit’s) are due to the action of the sun; that is, what would that scale indicate, supposing there were no sun—in other words, what is the temperature of space due to radiation from the stars, or other unknown sources ? Upon this point, namely, what would be the temperature of space if the sun did not exist, though there is not an absolute agreement among philosophers, yet the amounts arrived at by totally different methods are so nearly the same, as to inspire con- siderable confidence in their accuracy, or to lead us to regard them as making at least some approximation to the truth. From the relation of the temperature to the pressure Cu. XUIL] AND THE STARS. 279 of the atmosphere at different heights reached in balloons, Sir John Herschel infers that the heat of space if there were no sun would be 271° Fahr. below the freezing point of water, or— 239° Fahr.; and it is this number of degrees which, added to the number indicated at any moment by the ther- mometer, gives us the total absolute heat received at that moment from the sun ; and, according to him, we must have reference to this temperature of space in measuring the variations of heat and cold which must result from the erveater or less remoteness of the earth from the sun during the varying ellipticity of the earth’s orbit. The difficulty may be understood by supposing ourselves in a large hall 180 feet long, partly lighted by hundreds of candles so placed as that their light should be everywhere equally diffused, and partly by a central lamp. Then let this lamp be moved one foot and a half from the centre towards one end of the hall. This would increase the light received by an observer at that end, and diminish it to one at the opposite end, not in the proportion of one-thirtieth, or in that of its altered distance, but in proportion of one-fifteenth, the variation of the light being in an inverse ratio of the squares of the distance. But +n order to estimate the difference between the absolute quantity of light received by the two observers under this change of circumstances, we ought to know what proportion the light of the candles bears to that of the lamp, which, if we were not permitted to extinguish the latter, would not be easily arrived at. For what we are in search of is the relation of the solar to the stellar heat. Herschel considers it as proved that the power of the stars to heat space is very inferior to that of the sun.* Whatever be their influence in affecting the temperature of space, it is a constant quantity, or the same in all parts of the orbit of our planet, being wholly unaffected by its greater or less distance from the sun. If the difference of the heat received by the earth be in the ratio assumed by Herschel, it is not easy to reconcile geological phenomena with the exaggerated climates which variations of excentricity would cause, unless, indeed, the means of equalising through the year the heat and cold of * Trang. Geol. Soc. 2nd Series, vol. ii. p. 297. 280 CLIMATES OF THE SUCCESSIVE (Cu. XI, the two opposite extremes of aphelion and perihelion be ereater than is generally assumed. Under normal geo- eraphical circumstances, as well as those in which the area of sea in high latitudes is in excess, there would be scarcely if any permanent ice at either pole, and a freer circulation of oceanic currents from equatorial to polar regions than now; so that as the annual quantity of heat received from the sun is always equal, there would be no tendency in variations of excentricity to cause a general change of temperature. Climates of the successive phases of precession.—But there is another circumstance tending to the equalisation of the heat, which must be borne in mind, lest we should exaggerate the effects of excentricity on climate, even when intensified by such abnormal conditions of the earth’s geography as now prevail. We cannot divide the 21,000 years before spoken of as constituting the cycle caused by precession and the revo- lution of the apsides into two equal parts, as M. Adhémar and others have proposed, one of which in a given hemisphere should be a cold period when the winters coincide with aphelion, and the other a warm period when the winters coincide with perihelion. We must rather divide the cycle of precession into four quarters, in the first of which there is an accumulation of ice, because of the coincidence of the long polar night and the short days of all high latitudes with the greatest distance of the planet from the sun, or, in other words, because winter happens when the earth is at or within 45° of the aphelion, and because, in accordance with Mr. Croll’s hypothesis, the more intense heat of 5,250 sum- mers in perihelioh is so intercepted by fogs and clouds as to be unequal to the task of melting the snows of an equal number of winters. Then follows the next quarter, when the vernal equinox occurs at the least distance from the sun, and an equable climate is produced ; for the 5,250 winters and summers will be of nearly equal duration, and the summer and winter distances from the sun also equal, both of which causes will combine to make these seasons vary but little from the mean. In the third quarter the cold of all the winters is neutralised by proximity to the sun, while the heat of the stummers is in like manner moderated by the earth’s distance Cx. XIIL] PHASES OF THE PRECESSION. 281 from it, so that here again an equable climate is produced. In the fourth quarter, the autumnal equinox falling at, or within 45° of aphelion, the same effects will be produced as in the second quarter, and there will be no great exaggeration of heat or cold. Let us now consider how far extreme excentricity might contribute to intensify the cold if geographical circumstances were as favourable as they are now to the bringing on of a glacial period. Already the mere position of the polar lands gives rise toa great thickness of permanent ice at both poles, in regions where, at some former periods in our hemisphere at least, there was a luxurant vegetation. Let us suppose that extreme excentricity would in the first of the four quarters of precession before enumerated, add considerably, for reasons already stated, to the quantity and extent of perpetual snow in the arctic regions. Although the store of accumulated ice might be somewhat reduced during the second quarter, we have no right to infer from what now takes place at either pole, that the moderate temperature which would characterise generally the four seasons of the year, would get rid of the whole excess of ice which obtained at the commencement of this quarter. It has been imagined by Mr. Croll, that in the third quarter the thaw would be complete; but if, as appears to me inevitable, a large part of the ice-cap formed in the first quarter, and only partially reduced in the second, still surpassed in volume the ice now persistent in the arctic regions, I cannot comprehend on what principle such a thaw could be effected. The summers would be long, but extremely cold. If Herschel’s estimate of the temperature of space which Mr. Croll is willing to adopt, cives us even a rough approximation to the truth, we should have at London a mean temperature of about 32° Fahr., and in Iceland, 12° below freezing, while the severity of the climate between the arctic circle and the pole would be proportionally great. No doubt, the winter, which would be shorter than the summer by thirty-six days, would be very warm ; but, if in the first quarter the 5,250 intensely hot sum- mers could not prevent the accumulation of ice, how could the same number of winters, with a long arctic night between 282 CLIMATE AFFECTED BY VARIATION IN [Cu. XI. lat. 70° and the pole, and short days with the sun at a mode- rate height above the horizon in all temperate latitudes, exert a great melting power? We must also recollect what would now be going on at the opposite, or south pole, where the shortest day would coincide with the greatest distance of the earth from the sun. The ice there accumulated would re-act upon the northern hemisphere (the excentricity remaining undiminished), and under-currents of water far colder than any which belong to the ocean in our time would be flowing towards the equator. It is hardly necessary to say how little the equable climate of the fourth quarter could overcome all the excess of snow and ice which would thus have been formed at both poles; and it seems inevitable, that, whatever refrigerating effect extreme excentricity can produce in exag- gerating the cold, that effect must be cumulative during each successive cycle of precession, until the orbit becomes again more circular. The lowering of the temperature would be cosmical; there would be two antipodal ice-caps, one of them always greater in volume than the other, but neither of them of as moderate dimensions as those of the present epoch. Variation in the obliquity of the ecliptic.—Hitherto we have been considering the effect on climate of changes in the ex- centricity of the orbit, as if the earth’s axis of rotation were always inclined, as now, at an angle of 23° 28’ to the plane of the ecliptic; but it is well known that this angle is made to vary by about forty-eight seconds per century by the action of the planets on the earth, by which the plane of the ecliptic is now becoming more nearly coincident from year to year with the equator. This diminution of the obliquity will go on for ages, after which ‘it will again increase, and thus oscillate backwards and forwards about a mean position, the extent of its deviation to one side and the other being less than 1° 21’.* But Sir John Herschel informs me that although this limit as calculated by Laplace is true as. re- gards the last 100,000 years, yet if millions of years are taken into account, he thinks it conceivable that the devi- ation may possibly be sometimes greater, and may even be found to extend as much as three or even four degrees on * Herschel’s Astronomy, art. 640. Cu. XIII.] THE OBLIQUITY OF THE ECLIPTIC. 983 each side of the mean.* The questions entered into by Laplace and Leverrier respecting secular changes of the ecliptic relative to a fixed plane, and possible changes in the position of the earth’s equator, must be the subject of labo- rious computations before astronomers will have decided what may be the extreme range of obliquity, but they are agreed that it must be confined within very narrow limits. The re- sult of this movement, whether we adopt the higher or lower limit above alluded to, would be to lessen or augment, accord- ing to its direction, the effects to which the precessional move- ment gives rise. Whenever the obliquity is greater than now, more of the arctic and antarctic regions would be exposed to a long night in winter, and consequently the cold at that season would be greater, and, under the opposite circum- stances, the reverse would take place. The bearing of this cause on geological phenomena would be twofold. So often as the extreme of possible obliquity happened to combine with the maximum excentricity and with geographical cir- cumstances of an abnormal character like those now pre- vailing in high latitudes, a greater intensity of cold would be produced than could exist without such a combination, and so far this would favour a glacial epoch. But when, on the other hand, the obliquity was at its minimum, the cold would be lessened, even though all the other conditions which promote it were in full force. It may, however, be observed that the more numerous the astronomical causes in operation—such as precession, change of excentricity, and variation in the obliquity of the ecliptic, each of them being capable of acting independently of the others and of intensifying or extenuating the cold or heat— so much the greater is the likelihood that (within any given interval of time) they will counteract each other, instead of all of them conspiring in one and the same direction. And unless the geographical conditions, the most important of all, should happen to be in that exceptional state in which they exert a refrigerating influence, there would be no ten- dency in all the rest, in whatever way they might unite, to produce a colder climate. On the other hand, it may be * Letter to the Author, Oct. 1866. 284 RADIATION OF HEAT IMPEDED BY A (Ca. XIII. remarked that if the obliquity of the ecliptic could ever be diminished to the extent of four degrees below its present inclination, such a deviation would be of. geological interest, in so far as it would cause the sun’s light to be disseminated over a broader zone inside of the arctic and antarctic circles. This greater spread of the solar rays, implying a shortening of the polar night, would help in some slight degree to account for a vegetation such as now characterises lower latitudes having had, in the Miocene and Carboniferous periods, a much wider range towards the pole. If an adequate supply of light was afforded, the warmth required by such a flora would rarely have been wanting in past times, for, according to principles before laid down, a more genial climate would usually prevail in high latitudes, that is to say whenever the earth’s geography was in a normal state.* Radiation of heat impeded by a covering of snow.—Humboldt, in his treatise on isothermal lines published before 1820,+ ob- served that as the winter in the southern hemisphere is now longer by eight days, there must be a greater loss of heat by radiation into space than in the other hemisphere; and this observation would have still greater bearing on the problem now under consideration if, as would happen in extreme excentricity, the excess of winter over summer amounted to nearly forty days instead of eight. It must, however, be remembered that a covering of snow, extending over a larger n Mr. Meech’s valuable paper, be- length of path traversed by the oblique fore cited (p. 273), he treats of the rays, is given by Sir J. Leslie and Mr. effects of altered obliquity; but hestates Traill : (pp. 21 and 43) that his results as to Britann. From this it appears, that the intensity of solar radiation apply i only to the outside of the earth’s atmo- ceived at the = é itude 46 sphere. If his readers fail to bear this the poles will be as the numbers 115, in mind, they will be in danger of greatly 51, and 14 respectively. Even these overrating the increased kent in polar figures represent the comparative quan- regions cxaned Ly different phases of tity of heat at the higher latitudes as precession, excentricity, and obliquity of | being more than the truth; for they the ecliptic; for a large deduction will are computed on the supposition of con- have to be made for the greater amount stant sunshine. As cloud prevails to a of atmosphere through which the calo- greater extent in the high latitudes than rifie Ty6 must pass in very high lati- at the equator, the disproportion will tudes be increased The investigation of the true calorific ah Mémenes D’Are eil, ab ope effect of the sun’s rays for every 5° 462, translated in Hain. Phil. Journ., of altitude, allowing for the increased July 1820 Cu. XIII] COVERING OF SNOW AND ICE. 285 area and enduring for a longer time, must have the effect of preventing loss by radiation, snow being a very ad con- ductor of heat. It is observed in Canada and New England, that parts of a meadow which are laid bare in winter by the wind having blown away its snow, are often frozen for a depth of two feet or more, so that when spring returns this portion of the surface remains brown and barren while the rest of the field is green and clothed with a rapidly growing vegetation, a check having been given by the snow to the radiation of heat. Dr. Hooker found in like manner that, after the melting of the snow on the Himalaya, the warmth of the soil was far above the mean temperature of the region, owing to the same cause. In this way there may be some compensation, the excess of heat absorbed by the land, during a short but hot summer, being less freely parted with in winter owing to the snow. This loss by radiation during a protracted winter, is only one of many elements as yet undetermined which com- plicate the problem on which we are now speculating. Quantity of polar ice and its influence in altering the level of the ocean.—Among other data respecting which we require accurate information, and which at present the meteorologist cannot supply, is the quantity of ice now resting on land above the sea-level in the arctic and antarctic zones. Ante- cedently to experience it might have been thought that the thickness of the ice would increase as it extended northwards ; but Parry penetrated within about seven degrees, and Kane within five degrees, of the North Pole, and they both of them found open sea there, though they had reached a latitude so much higher than that in which the continent of Greenland is enveloped in a winding-sheet of perpetual snow. From such facts the geologist may learn that, although in the Glacial epoch certain mountain-chains and adjoining low- lands may have been buried in temperate latitudes under a vast covering of ice, yet the waters of the ocean in much higher latitudes may not at the same period have been frozen. We are by no means called upon as eeologists to embrace the opinion that an ice-cap once reached continuously from the pole to lat. 50°, still less to 40° in the temperate zone. It has long been a favourite opinion of northern voyagers that 286 LEVEL OF THE OCEAN AFFECTED BY [Cw. XTHT. there is open sea during part of the year at the pole itself, and the observations of Eschricht and Reinhardt on the migrations of the Greenland whale are rather confirmatory of this idea. It appears that this northern whale, Balena Mysticetus, is different from the whale called B. Biscayensis, a species now almost extirpated, and which once inhabited the British seas and the Bay of Biscay. In winter the Greenland whales accompany the ice when it floats farthest to the south in Baffin’s Bay, but in the summer, when the ice is only to be found farther north, they migrate to parts of the sea nearer the pole, having been seen as far north as man has yet penetrated. Apparently they retreat to the polar sea, which cannot therefore be covered by a continuous sheet of ice, for in that case they would be suffocated, since they must occasionally come to the surface to breathe. They could, however, pass under considerable barriers of ice pro- vided there were openings here and there; and so they may perhaps reach a more open sea near the pole, and find suste- nance there during a day of more than five months’ duration. The notion that we ought to find the ice continually increas- ing in thickness as we approach the pole would hardly be justified, even if the arctic land was so unbroken as to ex- clude the interference of oceanic currents conveying water from warmer to colder latitudes. For observations on the Swiss glaciers have shown to what an extent those rivers of ice are often lowered by evaporation, or by the passage of the ice into a gaseous form, without its having passed through the intermediate fluid condition. When certain dry winds blow, the snow wastes away like camphor without melting; and as we see the average number of inches of rainfall to diminish constantly, though very irregularly, as we pass from the equa- tor to the pole, so we may reckon on a diminution of the quan- tity of snow and the prevalence near the pole of a dry air, especially if there be snow-covered lands farther south inter- cepting aerial currents blowing from warmer regions, and causing them to part with their moisture in the form of snow. Mr. Darwin, during his visit to Central Chili, was informed that during one dry and very long summer all the snow dis- Cu: XIII.} THE QUANTITY OF ICE AND SNOW. 87 appeared from Aconcagua, although it attains the height of 23,000 feet. It is probable, he adds, that much of the snow at these great heights is evaporated rather than thawed.* In the Himalayas, where some of the mountain-peaks attain the height of 29,000 feet, the snow-line on the southern side of the chain occurs at 18,000, and on the northern at 16,000 feet, or, according to some authorities, 18,000. ‘For the moist winds of the south-west monsoon,’ says Herschel, ‘deposit their snow almost wholly on the southern side, while the northern is exposed to the evaporation of one of the driest regions of the globe.’ In like manner, when colder winds from the temperate zone first meet the frozen air of the arctic or antarctic regions, they will part with their moisture, so that the snow will increase on the outer margin of the antarctic con- tinent rather than in the interior. As it is well known that great falls of snow take place chiefly when the thermometer is about 32° F., and that little, if any, ever falls when the temperature is much lower, it would certainly be rash to assume that intense cold near the pole during the aphelion, when the excentricity is very large, tends to generate more snow than the dry atmosphere can absorb. Much snow was seen by Rink to have vanished from the surface of Greenland in the latter months of autumn, so that lines of erratic blocks were disclosed to view. In like manner, Ross and Hooker observed blocks of stone on the snows of Victoria Land—facts which would be inexplicable if much of the snow which falls annually were not removed from the surface by evaporation and liquefaction in high latitudes. Sir James Ross ascertained that the ice of the Great Antarctic Barrier, in lat. 78° south, rose only 150 feet above water, and he estimated its total thickness, above and below water for about 600 miles, to be not more than 1,000 feet. It is mere matter of conjecture what may be the thickness in the interior, since we are igno- rant of the height of the antarctic land. Humboldt calculated that the average thickness of snow on the Alps would be only 300 feet; for though it would be much thicker in many val- leys, it would be thin on the ridges and intervening table- lands. * Darwin, Journal of the Beagle, 1845, p. 245. 288 TEMPERATURE OF THE GLACIAL PERIOD. [Cu. XII, When we endeavour to estimate the mean thickness of the ice at present, we must allow in the north for large spaces where, instead of ice, there is a deep open sea; and even in regard toa continent like Greenland, we must remember that it is only at the termination of valleys or straths that Rink found great vomitaries discharging ice 2,000 feet thick into Baffin’s Bay. He counted twenty-two of these ice-streams ; but we may presume that on the intervening higher lands, parting the valleys which disgorge the ice, snow would never accumulate to more than a few hundreds of feet. If we were to imagine an average sheet of ice 2,000 feet thick, extending from the north pole to lat. 77°, and another 2,500 feet thick stretching from the south pole to lat. 70°, each ice-cap being continuous over the whole space now occupied by sea and land, this thickness would probably be nearer the truth than the extravagant estimates indulged in by some who have speculated on this subject. Several writers have fallen into the strange error of sup- posing that the Glacial Period must have been one of a higher mean temperature than usual, because an excess of snow implies an excess of evaporation, and consequently of heat. This fallacy has arisen from omitting the element of time from the calculation. No doubt the formation of so much snow requires that a corresponding quantity of water should be converted by heat into vapours; but we must také into account the number of years over which the process of dis- tillation was spread. If the summer’s warmth cannot get rid of all the winter’s snow, even by a few feet in a century, there will, in the course of thousands of years, be as large a store of ice formed as geologists may require. That in the Glacial Period there was a larger volume of ice in high latitudes than now exists there, we are, I think, war- ranted in concluding from geological evidence, even admitting that the extreme growth of the northern and southern ice- caps would never occur simultaneously. But although we find the monuments of extinct glaciers in the southern parts of New Zealand and South Australia, as well as in some cor- responding low latitudes in the northern hemisphere, espe- cially in North America, we can by no means infer that the Cu. XIIT.] TEMPERATURE OF THE GLACIAL PERIOD. 2RY ice ever extended continuously over the whole space now occupied by sea and land to about the 40th parallels of latitude. The relaxation of the cold during the milder climate of three out of four phases of the cycle of precession may have prevented the annihilation of many species of plants and animals which would have perished, especially in the tropical zone, if they could not during the coldest phase have migrated across the line into the opposite hemisphere. The number of species both of plants and animals which have survived the Glacial Period in temperate latitudes, is a fact warning us not to exaggerate the intensity and range of the cold beyond those limits which we are compelled to admit in order to explain geological phenomena. M. Adhémar considered the antarctic ice to be so volumi- nous as to draw towards it, by the force of gravitation, the waters of the ocean in such a degree as to cause the submer- gence of much land inthe southern hemisphere. The same force of attraction is appealed to by Mr. Croll as a cause of submergence of much land at one pole in the Glacial Epoch, but with this difference, that he refers the excessive accumulation of ice to the refrigerating effects of precession combined with a large excentricity. To do justice to this question would lead me into too long a digression; but there can be no doubt that, if there was an epoch—the Miocene, for example—not very remote in the great geolo- gical calendar, when there was no permanent snow and ice even at the poles, and if this was succeeded by a long period, when there were two ice-caps extending over the north and south polar lands, varying perhaps from 2,000 to 5,000 feet in average thickness, such piling up of ice above the sea-level would affect that level in various ways and the melting of a large part of the same, after the intensity of the cold had abated, would, so far as the thaw extended, restore the ocean to its former level. But in the present state of science, we cannot safely speculate on this subject, from our ignorance of the quantity and extent of the ice when it was most in excess, and from our inability to decide how far the ice-cap of one hemisphere in which VOL. I. U 290 TEMPERATURE OF THE GLACIAL PERIOD. [Cu. XII, winter was in aphelion predominated in size over the anti- podal ice-cap. Physicists, moreover, are not yet agreed as to the extent to which the waters of the ocean would gravitate ‘towards such an accumulation of polar ice. We must also take into our account the fact, that as the snow is not borrowed from another planet, but is taken from our ‘sea by evapo- ration, the general level of the ocean must be lowered’ by the abstraction from it of so much water.’ This depression of level would be universal, but in hich latitudes it would be counteracted to a certain extent ‘by the gravitation of the sea towards the polar ice-caps. On the other hand, the two antipodal ice-caps would, to a certain extent, counteract and neutralise each other’s power ; for in propor- tion as they drew the ocean towards them, they would lower its level, not only in the equatorial zone, but in the higher latitudes of the opposite hemisphere. The quantity of snow also, which during the Glacial Period would be perpetual on mountain-chains, even at the equator, and still more between latitudes 20° and 45°, such as the Himalayas, parts of the Andes north and south of the line, and part of Brazil, would have to be allowed for as sources of counter-attraction to the ice at the two poles. When, therefore, the geologist wishes to decide whether certain ancient lines of sea-margin, thirty, fifty, or several hundred feet above the level of the sea, may have been due to the former attraction of a northern ice-cap, which caused the land to be submerged for ages, until it re- emerged after the great thaw, he is at once involved in the difficulty of having to contend with all the uncertain data above enumerated. If, on the other hand, he should be inclined to ascribe the submerged forests on our coasts to a rise of level consequent on the thaw, or the restoration of so much water to the ocean, he will have to consider how large a volume of ice must be melted in order to produce such an effeet, and to learn from the botanist whether the trees of the submarine forests are of species proper to that more northern climate which the former prevalence of so much snow and ice would imply. It would: be preposterous to pretend that the sub- mergence of land 1,400 feet high, like that of Moel Tryfaen, Cu. XI.) DATE OF THE GLACIAL PERIOD. 291 covered with marine shells. as ‘before cited; and the date of which is subsequent tothe beginning of the Glacial. Epoch, could be accounted for by the attraction of polar ice, as the entire ocean would scarcely supply water enough. to form an ice-eap.of the required thickness... We are compelled, there- fore, to. admit great modern changes in the: relative level. of sea and land, wholly independent of elacial conditions, and due to such movements as are now going on in Sweden. and Greenland, or in the volcanic and coral areas. of the Pacific.* How. far a, date can‘ be ‘assigned to the Glacial. Period. by reference to former eras of large excentricity.—From what, 1 have already said. inthis and the preceding chapter, it will be ‘seen that I.consider the former changes, of climate and the quantity of ice now stored up in polar latitudes. to. have been governed chiefly. by geographical conditions... If, as.is very probable, a much larger excentricity of the earth’s orbit, as, suggested. by Mr. Crollj combined with that excess, of polar, land, which [ consider essential, would, give.rise to an exaggeration of the cold of both hemispheres, and, would espe- cially augment the ice at that pole the winters of which, oc- eurred in aphelion, it would follow that.we might obtain from the astronomer some aid in fixing the date of what we call the Glacial Period: We might the more reasonably indulge such a hope, because that period was so modern that, during the whole of it, nearly all the animals and plants inhabiting the northern hemisphere were the same.as those now in exist- ence... It is therefore a matter of no,small interest to. ascer- tain the dates of those variations in the excentricity of the orbit which may throw light on the times when. the cold first came on, when. it, reached its height, and when it was succeeded by the great thaw. which reduced the ice to its present limits. On my applying to the Astronomer Royal, Mr. Airy, for assistance in this enquiry, he suggested to Mr. Stone, of the Greenwich Observatory, to make, some of the required ealcu- lations ;; and that eminent’ mathematician undertook, by the * The reader is referred to important zine 1865 and 1866, in which the sup- papers by Messrs. Heath, Croll, Moore, posed effect of polar ice-caps on the and Pratt, in the Philosophical Maga-. ‘level of the ocean is ably discussed. u 2 292 DATES OF THE VARIATIONS IN [Cu. XII. ia use of Leverrier’s formula, to determine when the last high excentricity occurred. He found that it happened 210,065 years ago,* and that no other excentricity approaching to this in amount could be obtained by going back half million of years from the present era. The difference between the greatest and least distances, at the time alluded to by Mr. Stone, was about eleven million of miles, while at the maxi- mum the difference was about fourteen million. At present it is about three million, so that the proportions of distance are expressed by the figures 3-11-14. Hence, as Mr. Stone observes, ‘ whatever climatic changes may have taken place at some distant period through the existence of the absolute maximum of excentricity, corresponding, and but slightly inferior changes must have taken place about 210,000 years before the beginning of the present century.’ On this subject I may observe, that when we are endeavouring to appreciate the effects on climate to which excentricity alone may con- tribute, we are always more likely to be correct in our estimate in proportion as the time to which we refer is less remote, because this cause is less likely to have been con- trolled by altered geographical circumstances. If, for ex- ample, an astronomer should tell us of a large excentricity which took place a million or more years before our time, and we were to speculate on its connection with the Glacial Epoch, we might easily fall into the error of attributing to an astronomical cause what was really due to an altered state of physical geography as it may have existed in high latitudes at the period in question. For we are sure that considerable fluctuations in the position and in the height and depth of land and sea would have taken place in a million of years, but in proportion as the date of the large excen- tricity is less remote, the objection becomes less applicable. Mr. Croll, following up the series of calculations begun by Mr. Stone, rendered a great service to science by accomplish- ing the laborious task of computing the changes of excen- tricity for a million years preceding and a million following A.p. 1800. I have taken the two first columns of the annexed * Letter to the author, May 15, 1865; and see Phil. Mag., June, 1869. Cu. XUL.J THE EXCENTRICITIES OF THE ORBIT. 293 and the results given in the other table from his memoir, ted by my friend Mr. John four columns have been compu Carrick Moore, who by his mathematical and geological knowledge has rendered me ‘nvaluable assistance in all these enquiries on changes of climate. It appears to me that the third and fourth columns, in particular, will help the reader more clearly to appreciate the variations in temperature which are indicated by the figures in the second column. A glance at this table will show that there are four periods in the course of the last million of years, namely, those faced A,B, C,-D,.in which there has been a large excen- TaBLE SHOWING the variations in the excentricity of the earth’s orbit for a million years before A.D. 1800, and some of the climatal effects of such variations. 0 — | | 1 2 | ra ee es ha | a4 = | re Hee aes Po ___—_| | Differ- Mean of Mean of | Number of Excentri- | ence of | Number | _ hottest coldest | years before city of distance | of winter| month in month in | A.D. 1800. orbit. | in mi Jaysin | _lat. of lat. of | lions of cess | London. London. | miles. | | | ee ee ere eee | 1,000,000 | °0151 | 93 | 73 | 93° F.| 21° F. | 50,000 | -0517 | 94 | 25-1 | 109° 3° 900,000 | 0102 | 14 | 49 ae 23° | fa | 850,000 | -0747 134 | 36-4 | 126° Liege ic] Ci 5 ,000 0132 21 | 64 | 82° ) | c 750,000 0575 104 | 27:8 | 113° 026 | .000 220 4 | 102 | the 7) 650,000 0226 | “RS ae er et ier | 600,000 | “0417 | 74 | 208 | 1019-9 | 70-9 | 550,000 0166 | 3 Bis) 225 B4° 20° | ,000 oe er! 18°8 | 99° 9° | 450,000 0308 | 53 15 94° 13° 400,000 0170 3 G2. 1'< Bt? 20° | 350,000 0195 34 | 975 |. 86° 1S ae 300,000 0424 73 20-6 102° 7? 250,000 0258 44 125 90° 15° | B 4 210,000 0575 | 104 | 27°8 113° 0°.7 | b 200,000 0567 102 Q7°7 113° 19-9 | 150,000 0332 6 16°1 95° 12° | A ,000 0473 8h oe 5° 50,000 0131 24 63 | 82° 99. -, | 0168 3 81 | 84° 40° | EXPLANATION OF THE TABLE. Column 1. Division of a million years preceding 1800 into twenty equal parts. umn 2. Computed by Mr. James Croll by aid of Leverrier’s formula, gives the excentricity of the earth’s orbit in parts of a unit equal to the mean distance or half the longer diameter of the ellipse. ‘olumn 3. Which, together with the three following columns, has been computed 994 DATES OF THE. VARIATIONS IN [Cu. XT. y Mr. John Carrick Moore, gives in millions of miles the difference between the es and least distances of the earth from the sun, during the excentricities given in column 2 Column 4. Gives the number of ‘days'by which winter oécurring in aphelion: is longer than the summer in perihelion. Column 6. Gives the mean temperature of the hottest summer month in the latitude of London when the summer occurs in perihelio Column 6..Gives the mean temperature o of the ae winter month: in: the latitude of London when the winter occurs in aphelion,* tricity. For in A it was nearly three times as great as it is at present; in B three and a half times; in C we find two periods, one three and a half and the other four and a half times as great, with an intervening smaller excen- tricity ; and lastly in the period D, more than three times the present excentricity. If we could be sure that the greatest of these extremes, Ca, in which the distance of miles was 133 millions, was sufficient to produce glacial phenomena so much beyond those which the mere excess of polar land would occasion, we can hardly refuse to infer that the other distances, Cc, B, and A, although of subordinate magnitude, would have left to the geologist some recognisable proofs of their refrigerating influence. The periods of A and B would not, I conceive, be sufficiently distant from our era to afford time for that series of glacial and post-glacial events which we can prove to have happened since the epoch of the greatest cold. These events relate to changes in the level of the land in opposite directions, as well as the excavation of valleys, and variations in the range and distribution of aquatic and terres- trial animals, all of which take place at so slow a rate that 200,000 years would not be sufficient to allow of the series of changes with which we are acquainted. I agree, therefore * Supposing the mean temperature» and similarly the temperature of the of the hottest and eee | months at hottest’ northern summer month in London to be 64° F. and 38° F., respec- perihelion from the formula ore: the temperature ae space to be 939° + 10168? — 239° F., the present excentricity being ey ie rd 00168, and the north winter occurring ; ane She ee ; ; in perihelion, then the temperature (¢) Sir John Leslie and Mr. Traill give of the coldest. northern winter month | 64°67, and Dove 63°-08, for the fempe- when in aphelion for excentricity (e) | rature of the iattegt month in the will be found from this equation latitude of Londor 239° 4 ¢ _ 0-9832/? The above a must be taken as ‘ A ea mere rouch ap oroximations. 2399.4 38° Lee: : Bh APE Cu. XU] THE EXCENTRICITIES OF THE ORBIT. 295 with Mr. Croll, that if the date.of the most intense glacial cold. can. be arrived at. by aid of a very large excentricity, it would be a more probable conjecture to assign © than Bas the period in question. Without indulging at present im any sanguine anticipa- tions of success in chronological speculations of this nature, it may be useful to take a retrospective survey of some of the most prominent of the geological monuments viewed in their bearing on climate which have been observed in the northern hemisphere, within the period comprised in the above table. We have only to go back 8,000 years before historical times, in order to find the northern hemisphere in that phase of precession when winter occurred in aphelion ; and if, accord- ing to Herschel’s estimate, the summers were 12° hotter and the winters 12° colder than they are now, (the excentricity being nearly as moderate as at present,) we might expect to meet with some indications of a difference in climate in the flora and fauna of the earliest Swiss lake-dwellings and Danish kitchen-middens, assuming that the date of any of these fell within the era alluded to. It might therefore be argued that as the wild animals and plants of the Neolithic period were so precisely what they are now, this Neolithic period cannot date back so far as 11,000 years before our time; and if, as shown by Dove’s tables, and for reasons already explained, the planet is now warmest in June when the earth is farthest from the sun, the effects: of pre- cession in exaggerating the summer heat ought to have been great indeed when all this land was presented. to the sun in perihelion. Such hot summers would be equally adverse to the hypothesis which would assign so modern a date to the Reindeer period when, as we have before seen, man co-existed with the last surviving mammoths, and when some other northern quadrupeds extended their range, like the reindeer, to the south of France. If, on the other hand, we were to suggest that A might be the date of the Reindeer period, when the excentricity was nearly three times as great as at present, the antiquary might demur, objecting that the state of the arts and the condition of the caves of that epoch are not distinct: enough from those of the Neolithic to warrant us in supposing them to be nearly 100,000 years older. 296 DATES OF THE VARIATIONS IN (Cx. XT. As to the period B, it would not be difficult to imagine that this might have coincided with those Paleolithic times, - when man co-existed with a great many species of mammalia, now extinct, and when the caves containing the bones of such animals as well as human remains bore a relation to the drainage of the country and levels of the valleys, differing widely from the state of things now established. We may.also conceive the migration of quadrupeds from northern and southern provinces into the basins of the Seine and Thames to have taken place during the alternate warmer and colder phases of precession, when the climate was under the influence of an excentricity nearly four times greater than that of our era. The carcasses of the elephant and rhinoceros may then have been enveloped in Siberian ice; but if so, we must assume that neither the summers nor winters in peri- helion have at any subsequent period had power to melt so much ice as to expose these carcasses to decomposition—a fact which implies a persistent polar ice-cap during each phase of precession. When we pass beyond the era B, we find an interval of more than half a million of years without an excentricity so large as A and B before mentioned, although it embraces three periods in which the excentricity was more than double what it now is. In such a lapse of ages, changes in physical geography may have exercised considerable influence in siving rise to oscillations of temperature, even though the proportion of polar land was always in excess. It would, therefore, be very hazardous to exclude all these ages from the Glacial Period, merely on the grounds that such intensity must have coincided with a higher excentricity than is sup- plied by that long interval. If, indeed, we could make such an assumption, the period C would, as Mr. Croll suggests, have the best claim to be the epoch of extreme cold, notwithstanding that the intervening era Cb presents us with an excentricity smaller than that of the present times intercalated between Ca, four and a half times greater than the present, and Ce three and a half times greater. The whole duration of C might be said to comprise about six complete cycles of precession, because one of them would Cu. XIII] THE EXCENTRICITIES OF THE ORBIT. 997 have been run through before the excentricity reached ‘0747, if we jnclude all excentricities equalling 05 as periods of great cold. But two of these six cycles, which occur in the middle of the period would belong to an excentricity approaching to that of our era, during which time the great accumulation of snow, which may be supposed to have taken place during Ca, may have been considerably reduced, after which it would again begin to increase. The antecedent epoch D might belong to those ages when changes in physical geo- graphy may have been bringing on the first approach of a glacial epoch towards the close of the Newer Pliocene Period. Independently of all astronomical considerations, it must, T think, be conceded that the period required for the coming on of the greatest cold, and for its duration when most in- tense, and the oscillations to which it was subject (p. 195), as well as the retreat of the glaciers and the ‘ great thaw 2 OF disappearance of snow from many mountain-chains where the snow was once perpetual, required not tens but hundreds of thousands of years. Less time would not suffice for the changes in physical geography and organic life of which we have evidence. Toageologist, therefore, it would not appear startling, that the greatest cold should be supposed to have coincided with the period C as before hinted, or that some of the earliest groups of marine shells, such as those of Brid- lington and Chillesford alluded to at p. 197, might go back as far as the period D. Provided a predominance of land in high latitudes be granted, the fact which would seem to me most favourable to the connection of a large excentricity with an excess of cold is the following :— By referring to the map of Isothermal Lines (fig. 9, p. 238), the reader will see that the mean annual isothermals of 14°, 93°, 32°, 41° and 50° Fahr., are all of them in their range from Europe to North America deflected from 18° to 18° of latitude in a southerly direction in their passage from east to west. The late Edward Forbes has also shown in one of his maps,* that the living arctic fauna extends in like manner * Memoirs of the Survey of Great Britain, vol. i. plate vu. 298 ASTRONOMICAL AND GEOGRAPHICAL CAUSES (Cu. XI 10° farther south on the west side of the Atlantic than on the east side. This difference, as before pointed out, p. 236, is dependent on purely geographical and not on astronomical causes—the direction of the Gulf-stream from south-west to north-east—the cold polar current flowing south along the east coast of North America—the extension of the land of the latter continent continuously towards the pole in the same latitudes as those where there is open sea to the north of Europe, are sufficient to explain the present course of the isothermals; and if the cold were now augmented: by the coming on of a large excentricity, the isothermals alluded to would exhibit the same curves, their position being shifted farther south because the new refrigerating influence would operate equally on the eastern and western hemisphere. If, the effect would not be exactly equal on both sides of the Atlantic, it would be in favour of greater curves in the direction in which they now bend, because the increase of snow and ice would be greatest on the side where there is most land in very high latitudes. Now we find that in the Glacial Period all signs of glacia- tion, such as erratic blocks, scored surfaces of rock, striated boulders, and deposits filled with arctic species of marine shells; are to be seen in full force on the North American continent ten or more degrees farther south than in Hurope. If we could assume, therefore, that geographical conditions had been constant, these phoneme would be in favour of our attributing the greater intensity of cold in the Glacial Period to a maximum excentricity. Our full reliance, how- ever, on this line of reasoning is somewhat weakened when we reflect that a moderate amount of geographical change in a very high latitude—such as the addition of some islands near the pole, or the increased height of some of the land now existing between latitudes 70° and 80° N.—might exaggerate the cold both of the eastern and western hemispheres, acting alike on northern Hurope and North America. We know, a positive fact, that geographical changes have taken place i the height and position of land since the commencement of the Glacial Period, although we cannot affirm that when the cold was at its height there w was a greater proportion of Cx: XII] AFFECTING THE GLACIAL PERIOD. 299 land in high. latitudes than at present. If at that time it were in excess, we are more certain that the change alluded to. would. intensify the cold than we are that a change of excentricity would have the same effect; for the last-men- tioned conclusion depends upon the soundness of the hypo- thesis that, in spite of the annual supply of solar heat being always equal, the more imtense heat of summer cannot over- come the increased winter’s cold whenever the latter gives rise to a much greater snow-fall. If the sketch which’ we have given in the ‘tenth and eleventh chapters of the former states of climate revealed to us by paleontological research be an approximation to the truth, it will at once be seen that glacial periods have not been perpetually recurring in the northern temperate gone, as they ought to have done were a large excentricity alone sufficient, apart from the cooperation of all other causes, to intensify the cold of high latitudes. It was shown that the flora and fauna do not exhibit signs of violent revolutions from: hot to cold and from cold to hot periods. On the con- trary, the continuity of forms, particularly in the class of reptiles, from the Carboniferous to the Cretaceous Period, is opposed to the intexcalation of glacial epochs corresponding in importance to that of Post-pliocene date. During the Carboniferous Period there must have been a long suspen- sion in the temperate latitudes of the northern hemisphere, of cold such as we now experience. An equable climate must have endured for a lapse of centuries, sufficient to allow several great cycles of excentricity to be gone through. But-we do not find in strata of that age 15,000 feet thick in. Nova Scotia any proofs of such intercalated glacial epochs. The peculiar vegetation of the coal was persistent throughout the greater part of the ages required for the deposition of so great a thickness of sediment in which one forest after another was buried on the spot where it had grown.* The absence of recurrent periods of cold is perfectly explicable, if I am right in concluding that they can only be brought about. by an abnormal quantity of land in high latitudes ; for under ordinary geographical conditions * See Elements of Geology by the Author, p. 482. 300 DURATION OF THE GLACIAL, TERTIARY, ([Cu. XIII. a maximum excentricity would only tend to render the climate less equable, and not colder. If the ocean prevailed in the polar regions there would be no snow, or no more than the summer’s thaw would dissipate ; and the difference in the total quantity of heat being as 1003 to 1000, may, as Sir J. Flerschel observes, be neglected, and would, as before stated, if appreciable, have a heating and not a refrigerating influence. The attempt, therefore, to assign a chronological value to any of our geological periods except the latest, must, in the pre- gent state of science, be hopeless. We may imagine an ex- treme excentricity and winter in aphelion to have sometimes co-operated, with favourable geographical conditions, to produce an excess of snow, and in this manner we may en- deavour to account for some instances of local glaciation such as those alluded to at pages 207 and 209, where the move- ments of ice-action are intercalated in the middle of a series of deposits, the fossils of which indicate a warm climate. Comparative duration of the Glacial and the antecedent Ter- tiary, Secondary, and Primary Epochs.—But we obtain no positive dates from such a source, and the utmost to which we can aspire at present is to form some conjectures respect- ing the relations of the Glacial Period to the present time, by aid of such data as are afforded by the table given at p. 293. Suppose, for example, in accordance with the views before set forth, we could assume that the coming on of the Glacial Period happened a million years before our time, we should then have obtained some insight into the amount of change in the marine testacea which that number of years has brought about. Accordingly, when we find that ninety-five in a hundred of the shells of the period alluded to were specifically identical with those now inhabiting the northern hemisphere, we may considera million years to represent the twentieth part of a complete revolution in species, and we might thus estimate the number of years required for the elaboration of the successive Tertiary formations; nor should we be in danger, according to the theory of developement or transmutation of species, of exaggerating the rapidity of the rate at which the old forms were supplanted by new ones, because a general refrigeration of climate and several oscilla- Cu. XII] SECONDARY, AND PRIMARY EPOCHS. 301 tions of temperature during the Glacial Epoch, and the con- sequent migrations of plants and animals, ought to have had an accelerating rather than a retarding influence on the usual rate of fluctuation. We must go back as far as the older Miocene formations of our table at p. 139, in order to arrive at a period when the marine shells differ as a whole from those now existing. The antecedent Tertiary strata from the beginning of the Hocene to the close of the Lower Miocene comprise two ereat revo- lutions in organic life, as measured by the change of testacea, each of them equal in magnitude to that which has happened in the interval which separates the Lower Miocene period from our times. So that we should thus obtain three periods, although they would not answer precisely to the terms Hocene, Miocene, and Pliocene in our table. A fourth of equal dura- tion is indicated by the change in organic life which occurred between the end of the Cretaceous and the. beginning of the Hocene epoch, a great gap, to which as yet few geological records refer. Each of these four periods would lay claim to twenty million of years, if the Glacial Period, for reasons above stated, expresses the twentieth part of one complete revolution in species. The antecedent Cretaceous, Jurassic, and ‘Triassic formations would yield us three more epochs of equal importance to the three Tertiary periods before en- umerated, and a fourth may be reckoned by including the Permian epoch with the gap which separates it from the Trias. To these eight periods we may add, continuing our retrospective survey, four more, namely, the Carbonifer- ous, Devonian, Silurian, and Cambrian; so that we should have twelve in all, without reckoning the antecedent Lau- rentian formations, which are older than the Cambrian or ‘the primordial rocks’ of Barrande. If each, therefore, of the twelve periods represents twenty million of years on principles above explained, we should have a total of two hundred and forty millions for the entire series of years which have elapsed since the beginning of the Cambrian period. Supposed variations in the temperature of space.—Another astronomical hypothesis respecting the possible cause of secular variations in climate, has been proposed by a dis- 302 VARIATIONS IN TEMPERATURE OF SPACE. (Ca. X11, tinguished mathematician and philosopher, M. Poisson. «He begins by assuming, Ist, that the sun and our planetary system are not stationary, but carried onward by a common movement through space; 2dly, that every point ‘in space receives heat as well as light from innumerable stars sur- rounding it on all sides, so that if a right line of indefinite length be produced in any direction from'such point, it must encounter a star either visible or imvisible to us. 3dly, he then goes on to assume, that the different regions of space, which in the course of millions of years are traversed by our system, must be of very unequal temperature, mas- much as some of them must receive a greater, others a less quantity of radiant heat from the great stellar inclosure. If the earth, he continues, or any other large body, pass from a hotter to a colder region, it would not readily lose in the second all the heat which it has imbibed in the first region, but retain a temperature increasing downwards from the surface, as is the actual condition of our planet.* Now the opinion originally suggested by Sir.W. Herschel, that our sun and its attendant planets were all moving onward through space, in the direction of the constellation Hercules, is very generally thought. by. modern astronomers to be confirmed. But the amount of the movement ‘is still uncertain, and great indeed must be its extent before this cause alone can work any material alteration in the.terrestrial climates. Mr. Hopkins, when treating of this theory, re- marked, that so far as we are acquainted with the position of stars not very remote from the sun, they seem to be so distant from each other, that there are no points in space among them, where the intensity of radiating heat would be comparable to that which the earth derives from the sun, except at points very near to each star. Thus, in order that the earth should derive a degree of heat from stellar radia- tion comparable to that now derived from the sun, it must be in close proximity to some particular star, leaving the ageregate effect. of radiation from the other stars nearly the same as.at present. This approximation, however, toa single * Poisson, Théorie Mathémat. de la Chaleur, Comptes Rendus de I’ Acad. des Sci., Jan. 30. 1837. Cx. XTIL-] SOLAR MAGNETIC: PERIODS. 303 star could not take place consistently with the preservation of the motion of the earth about the sun, according to its present laws. Suppose our sun should approach a star within the present distance of Neptune. That planet could no longer remain a member of the solar system, and the motions of the other planets would be disturbed in a degree which no one has ever contemplated as. probable since the existence of the solar system. But such a star, supposing it to be no larger than the sun, and to emit the same. quantity of heat, would not send: to the earth much more than one-thousandth part of the heat which she derives from the sun, and would therefore produce only a very small change in terrestrial temperature.* Solar magnetic periods and variable splendour of the stars.— Schwabe observed in 1852, that the spots on the ‘sun alternately increase and decrease in the course of every ten years; and General Sabine has pointed out that this variable obscuration coincides in time, both as to its maximum and minimum, with changes in all those terrestrial magnetic variations which are caused by the sun. Hence he infers that the period of alteration in the spots is a solar magnetic period. Assuming this to be the case, we may naturally enquire whether the variable light of some stars may be connected with stellar magnetic periods.. It may be said that, hitherto, observation has failed to prove that there is the slightest variation in the light and heat of the sun coin- cident with an increase in the number and magnitude of the spots. In May 1866, there was.a temporary outburst of light ina star in Corona Borealis, causing it to become as brilliant dda star of the second magnitude. In twelve days it declined to the brightness of a star of the eighth magnitude... The light was submitted by Mr. Huggins and Dr..W. A. Miller to the test of spectrum analysis, and the result of the ex- periment seemed clearly to indicate that the light had a gaseous source, and was produced by hydrogen burning about the star in combination with some other element.t Supposed gradual diminution of the earth’s primitive heat.— * Quart. Journ. Geol. Soc. 1852. t+ W. Huggins, F. R. S., Quart. Journ. p. 62. of Science, July 1866. 304 NO SENSIBLE CONTRACTION OF GLOBE. (Cu. XII. The gradual diminution of the supposed primitive heat of the globe has been resorted to by many geologists as the principal cause of alterations of climate. The matter of our planet is imagined, in accordance with the conjectures of Leibnitz, to have been originally in an intensely heated state, and to have been parting ever since with portions of its heat, and at the same time contracting its dimensions. There are, undoubtedly, good grounds for inferring from recent, observa- tion and experiment, that the temperature of. the earth increases as we descend from the surface to that slight depth to which man can penetrate: but there are no positive proofs of a secular decrease of internal heat accompanied by con- traction. On the contrary, Laplace has shown, by reference to astronomical observations made in the time of Hipparchus, that in the last two thousand years at least there has been no sensible contraction of the globe by cooling; for had this been the case, even to an extremely small amount, the day would have been shortened, whereas its length has certainly not diminished during that period by ;4,;th of a second. I shall allude in the second volume to many objections which may be urged against the theory of the intense heat of the earth’s central nucleus, and shall then enquire how far the observed augmentation of temperature, as we descend below the surface, may be referable to other causes uncon- nected with the supposed pristine fluidity of the entire globe. In the same chapter I shall treat of speculations on the shifting of the position of the earth’s axis of rotation and of its centre of gravity; also of the supposed sliding of a rigid crust over an internal fluid nucleus, recently advanced by Mr. Evans to explain the altered climates of the habitable surface in certain latitudes. 805 CHAPTER XIV. UNIFORMITY IN THE SERIES OF PAST CHANGES IN THE ANIMATE AND INANIMATE WORLD. SUPPOSED ALTERNATE PERIODS OF REPOSE AND DISORDER—OBSERVED FACTS IN WHICH THIS DOCTRINE HAS ORIGINATED—THESE MAY BE EXPLAINED BY FOLD CONSIDERATION OF IS SUBJECT; FIRST, IN REFERENCE TO THE ‘0 SHIFTING OF THE AREA OF SEDIMENTARY DEPOSITION uu By E MODES AND CAUSES OF CHANGE IN PRODUCING BREAKS AND CHASMS IN THE CHAIN OF RECORDS—CONCLUDING REMARKS ON THE IDENTITY OF THE ANCIENT AND PRESENT SYSTEM OF TERRESTRIAL CHANGES. Origin of the doctrine of alternate periods of repose and disorder.—Iv has been truly observed, that when we arrange the fossiliferous formations in chronological order, they con- stitute a broken and defective series of monuments: we pass without any intermediate gradations from systems of strata whichare horizontal to other systems whichare highly inclined, —from rocks of peculiar mineral composition to others which have a character wholly distinct,—from one assemblage of organic remains to another, in which frequently nearly all the species, and a large part of the genera, are different. These violations of continuity are so common, as to constitute, even in districts of considerable area, the rule rather than the exception, and they have been considered by many geologists as conclusive in favour of sudden revolutions in the inanimate and animate world. We have already seen that according’ to the speculations of some writers, there have been in the past history of the planet alternate periods of tranquillity and VoL. I. x 306 UNIFORMITY OF CHANGE. (Cu. XIV. convulsion, the former enduring for ages, and resembling the state of things now experienced by man: the other brief, transient, and paroxysmal, giving rise to new mountains, seas, and valleys, annihilating one set of organic beings, and ushering in the creation of another. It will be the object of the present chapter to demonstrate, that these theoretical views are not borne out by a fair inter- pretation of geological monuments. It is true that, in the solid framework of the globe, we have a chronological chain of natural records, many links of which are wanting; but a careful consideration of all the phenomena leads to the opinion that the series was originally defective—that it has been rendered still more so by time—that a great part of what remains is inaccessible to man, and even of that frac- tion which is accessible nine-tenths are to this day unex- plored. The readiest way, perhaps, of persuading the reader that we may dispense with great and sudden revolutions in the geological order of events, is by showing him how a regular and uninterrupted series of changes in the animate and in- animate world may give rise to such breaks in the sequence, and such unconformability of stratified rocks, as are usually thought to imply convulsions and catastrophes. It is scarcely necessary to state, that the order of events thus assumed to occur, for the sake of illustration, must be in harmony with all the conclusions legitimately drawn by geologists from the structure of the earth, and must be equally in accordance with the changes observed by man to be now going on in the living as well as in the inorganic creation. It may be neces- sary in the present state of science to supply some part of the assumed course of nature hypothetically ; but if so, this must be done without any violation of probability, and always consistently with the analogy of what is known both of the past and present economy of our system. Although the discussion of so comprehensive a subject must carry the beginner far beyond his depth, it will also, it is hoped, stimulate his curiosity, and prepare him to read some ele- mentary treatises on geology with advantage, and teach him the bearing on that science of the changes now in progress Cu. XIV.] SEDIMENTARY DEPOSITION. 807 on the earth. At the same time it may enable him the better to understand the intimate connection between the Second and Third Books of this work, one of which is occupied with the changes of the inorganic, the latter with those of the organic creation. In pursuance, then, of the plan above proposed, I will con- sider in this chapter, first, the laws which regulate the deposition of sediment; secondly, those which govern the fluctuation in the animate world; and thirdly, the mode in which subterranean movements affect the earth’s crust. Uniformity of change considered, first, in reference to sedi- mentary deposition.—First, in regard to the laws governing the deposition of new strata. If we survey the surface of the globe we immediately perceive that it is divisible into areas of deposition and non-deposition; or, in other words, at any given time there are spaces which are the recipi- ents, others which are not the recipients, of sedimentary matter. No new strata, for example, are thrown down on dry land, which remains the same from year to year; where- as, In many parts of the bottom of seas and lakes, mud, sand, and pebbles are annually spread out by rivers and cur- rents. There are also great masses of limestone growing in some seas, chiefly composed of corals and shells, or, as in the depths of the Atlantic, of chalky mud made up of foraminifera and diatomacece. As to the dry land, so far from being the receptacle of fresh accessions of matter, it is exposed almost everywhere to waste away. Forests may be as dense and lofty as those of Brazil, and may swarm with quadrupeds, birds, and insects, yet at the end of thousands of years one layer of black mould, a few inches thick, may be the sole representative of those myriads of trees, leaves, flowers, and fruits, those innumer- able bones and skeletons of birds, quadrupeds, and reptiles, which tenanted the fertile region. Should this land be at length submerged, the waves of the sea may wash away in a few hours the scanty covering of mould, and it may merely impart a darker shade of colour to the next stratum of marl, sand, or other matter newly thrown down. So also at the bottom of the ocean where no sediment is accumulating, x2 308 CAUSES OF VARIATION [Cu. XIV. seaweed, zoophytes, fish, and even shells, may multiply for ages and decompose, leaving no vestige of their form or sub- stance behind. Their decay, in water, although more slow, is as certain and eventually as complete as in the openair. Nor can they be perpetuated for indefinite periods in a fossil state, unless imbedded in some matrix which is impervious to water, or which at least does not allow a free percolation of that fluid, impregnated, as it usually is, with a slight quantity of carbonic or other acid. Such a free percolation may be pre- vented either by the mineral nature of the matrix itself, or by the superposition of an impermeable stratum: but if unim- peded the fossil shell or bone will be dissolved and removed, particle after particle, and thus entirely effaced, unless petri- faction or the substitution of mineral for organic matter happen to take place. That there has been land as well as sea at all former geological periods, we know from the fact, that fossil trees and terrestrial plants are imbedded in rocks of every age, except those which are so ancient as to be very imperfectly known to us. Occasionally lacustrine and fluviatile shells, or the bones of amphibious or land reptiles, point to the same conclusion. The existence of dry land at all periods of the past implies, as before mentioned, the partial deposition of sediment, or its limitation to certain areas ; and the next point to which I shall call the reader’s attention, is the shift- ing of these areas from one region to another.. First, then, variations in the site of sedimentary deposition are brought about independently of subterranean movements. There is always a slight change from year to year, or from century to century. The sediment of the Rhone, for example, thrown into the Lake of Geneva, is now conveyed to a spot a mile and a half distant from that where it accumulated in the tenth century, and six miles from the point where the delta began originally to form. We may look forward to the period when this lake willbe filled up, and then the distribution of the transported matter will be suddenly altered, for the mud and sand brought down from the Alps will thenceforth, in- stead of being deposited near Geneva, be carried nearly 200 miles southwards, where the Rhone enters the Mediterranean. Cu. XIV.] IN MINERAL CHARACTER. 309 In the deltas of large rivers, such as those of the Ganges and Indus, the mud is first carried down for many centuries through one arm, and on this being stopped up it is dis- charged by another, and may then enter the sea at a point 50 or 100 miles distant from its first receptacle. The direc- tion, of marine currents is also liable to be changed by various accidents, as by the heaping up of new sand banks, or the wearing away of cliffs and promontories. But, Seite all these causes of fluctuation in the sedi- mentary areas are entirely subordinate to those great upward or downward movements of land, which will presently be spoken of, as prevailing over large tracts of the globe. By such elevation or subsidence certain spaces are gradually submerged, or made gradually to emerge: in the one case sedimentary deposition may be suddenly renewed after having been suspended for one or more geological periods, in the other as suddenly made to cease after having continued for ages. If deposition be renewed after a long interval, the new strata will usually differ greatly from the sedimentary rocks previously formed in the same place, and especially if the older rocks have suffered derangement, which implies a change in the physical geography of the district since the previous conveyance of sediment to the same spot. It may happen, however, that, even where the two groups, the superior and the inferior, are horizontal and conformable to each other, they may still differ entirely in mineral charac- ter, because, since the origin of the older formation, the geography of some distant country has been altered. In that country rocks before concealed may have become exposed by ‘denudation ; voleanos may have burst out and covered the surface with scoriz and lava, or new lakes, intercepting the sediment previously conveyed from the upper country, may have been formed by subsidence ; and other fluctuations may have occurred, by which the materials brought down from thence by rivers to the sea have acquired a distinct mineral character. It is well known that the stream of the Mississippi is charged with sediment of a different colour from that of the 310 UNIFORMITY OF CHANGE [Cu. XIV. Arkansas and Red Rivers, which are tinged with red mud, derived from rocks of porphyry and red gypseous clays in ‘ the far west. The waters of the Uruguay, says Darwin, draining a granitic country, are clear and black, those of the Parana, red.* The mud with which the Indus is loaded, says Burnes, is of a clayey hue, that of the Chenab, on the other hand, is reddish, that of the Sutlej is more pale.t The same causes which make these several rivers, sometimes situated at no ereat distance the one from the other, to differ greatly in the character of their sediment, will make the waters draining the same country at different epochs, especially before and after great revolutions in physical geography, to be entirely dissimilar. It is scarcely necessary to add, that marine cur- rents will be affected in an analogous manner in consequence of the formation of new shoals, the emergence of new islands, the subsidence of others, the gradual waste of neighbouring coasts, the growth of new deltas, the increase of coral reefs, volcanic eruptions, and other changes. Uniformity of change considered, secondly, in reference to the living creation.—Secondly, in regard to the vicissitudes of the living creation, all are agreed that the successive groups of sedimentary strata found in the earth’s crust are not only dissimilar in mineral composition for reasons above alluded to, but are likewise distinguishable from each other by their organic remains. The general inference drawn from the study and comparison of the various groups, arranged in chronological order, is this : that at successive periods, distinct tribes of animals and plants have inhabited the land and waters, and that the organic types of the newer formations are more analogous to species now existing than those of more ancient rocks. If we then turn to the present state of the animate creation, and enquire whether it has now become fixed and stationary, we discover that, on the contrary, it is in a state of continual flux—that there are many causes in action which tend to the extinetion of species, and which are conclusive against the doctrine of their unlimited durability. There are also causes which give rise to new varieties and * Darwin’s Journal, p. 163, 2nd. + Journ. Roy. Geograph. Soe., vol. . 139. iii. p. 142. ed. p mea deem S. Cu. XIV.] IN THE ANIMATE WORLD. 811 races in plants and animals, and new forms are continually supplanting others which had endured for ages. But natura! history has been successfully cultivated for so short a period, that a few examples only of local, and perhaps but one or two of absolute, extirpation of species can as yet be proved, and these only where the interference of man has been conspi- cuous. It will nevertheless appear evident, from the facts and arguments detailed in the Third Book, in the chapters which treat of the geographical distribution of species in the next volume, that man is not the only exterminating agent; and that, independently of his intervention, the annihilation of species is promoted by the multiplication and gradual diffusion of every animal or plant. It will also appear, that every alteration in the physical geography and climate of the globe cannot fail to have the same tendency. If we proceed stil! farther, and enquire whether new species are substituted from time to time for those which die out, and whether there are certain laws appointed by the Author of Nature to regulate such new creations, we find that the period of human obser- vation is as yet too short to afford data for determining so difficult a question. All that can be done is to show, that the successive introduction of new species may bea constant part of the economy of the terrestrial system, without our having any right to expect that we should be in possession of direct proof of the fact. To enable the reader to appreciate the eradual manner in which a passage may have taken place, from an extinct fauna to that now living, I shall say a few words on the fossils of successive Tertiary periods. When we trace the series of formation from the more ancient to the more modern, it is in these Tertiary deposits that we first meet with assemblages of organic remains, having a near analogy.to the fauna of certain parts of the globe in our own time. In the Hocene, or oldest subdivision, some few of the testacea belong to existing species, although almost all of them, and apparently all the associated vertebrata, are now extinct. These Kocene strata are succeeded by a great num- ber of more modern deposits, which depart gradually in the character of their fossils from the Hocene type, and approach more and more to that of the living creation. In the present 312 UNIFORMITY OF CHANGE [Cu. XIV. state of science, it is chiefly by the aid of shells that we are enabled to arrive at these results, for of all classes the tes- tacea are the most generally diffused in a fossil state, and may be called the medals principally employed by nature, in re- cording the chronology of past events. In the Upper Miocene rocks (No. 5 of the table p. 139) we begin to find a considerable number, although still a minority, of recent species, inter- mixed with some fossils common to the preceding, or Hocene epoch. We then arrive at the Pliocene strata, in which species now contemporary with man begin to preponderate, and in the newest of which nine-tenths of the fossils agree with species still inhabiting the neighbouring sea. It is m the Post-tertiary strata, where all the shells agree with spe- cies now living, that we have discovered the first or earliest known remains of man associated with the bones of quadru- peds, some of which are of extinct species. Tn thus passing from the older to the newer members of the Tertiary system we meet with many chasms, but none which separate entirely, by a broad line of demarcation, one state of the organic world from another. There are no signs of an abrupt termination of one fauna and flora, and the starting into life of new and wholly distinct forms. Although we are far from being able to demonstrate geologically an insensible transition from the Eocene to the Miocene, or even from the latter to the recent fauna, yet the more we enlarge and perfect our general survey, the more nearly do we ap- proximate to such a continuous series, and the more gradually are we conducted from times when many of the genera and nearly all the species were extinct, to those in which scarcely a single species flourished which we do not know to exist at present. Dr. A. Philippi, indeed, after an elaborate com- parison of the fossil tertiary shells of Sicily with those now living in the Mediterranean, announced, as the result of his examination, that there are strata in that island, which attest a very gradual passage from a period, when only thirteen in a hundred of the shells were like the species now living in the sea, to an era when the recent species had attained -a proportion of ninety-five in a hundred. There is, therefore, evidence, he says, in Sicily of this revolution in the animate | | | | | | | Cu. XIV.] IN THE ANIMATE WORLD. 313 world having been effected ‘without the intervention of any convulsion or abrupt changes, certain species having from time to time died out, and others having been introduced, until at length the existing fauna was elaborated.’ In no part of Europe is the absence of all signs of man or his works, in strata of comparatively modern date, more striking than in Sicily. In the central parts of that island we observe a lofty table-land and hills, sometimes rising to the height of 3,000 feet, capped with a limestone, in which from 70 to 85 per cent. of the fossil testacea are specifically identical with those now inhabiting the Mediterranean. These calcareous and other argillaceous strata of the same age are intersected by deep valleys which have been gradu- ally formed by denudation, but have not varied materially im width or depth since Sicily was first colonised by the Greeks. The limestone, moreover, which is of so late a date in geo- logical chronology, was quarried for building those ancient temples of Girgenti and Syracuse, of which the ruins carry us back to a remote era in human history. If we are lost in conjectures when speculating on the ages required to lift up these formations to the height of several thousand feet above the sea, how much more remote must be the era when the same rocks were gradually formed beneath the waters ! The intense cold of the Glacial period was spoken of im the tenth chapter. Although we have not yet succeeded in detecting proofs of the origin of man antecedently to that epoch, we have yet found evidence that most of the testacea, and not a few of the quadrupeds, which preceded, were of the same species as those which followed the extreme cold. ‘To whatever local disturbances this cold may have given rise in the distribution of species, it seems to have done little in effecting their annihilation. We may conclude therefore from a survey of the tertiary and modern strata, which con- stitute a more complete and unbroken series than rocks of older date, that the extinction and creation of species has been, and is, the result of a slow and gradual change in the organic world. Uniformity of change considered, thirdly, m reference to 314 UNIFORMITY OF CHANGE. [Cu. XIV. subterranean movements.—Thirdly, to pass on to the last of the three topics before proposed for discussion, the reader will find, in the account given in the Second Book of the earthquakes recorded in history, that certain countries have, from time im- memorial, been rudely shaken again and again; while others, comprising by far the largest part of the globe, have remained to all appearance motionless. In the regions of convul- sion rocks have been rent asunder, the surface has been forced up into ridges, chasms have opened, or the ground throughout large spaces has been permanently lifted up above or let down below its former level. In the regions of tranquillity some areas have remained at rest, but others have been ascertained by a comparison of measurements, made at different periods, to have risen by an insensible motion, as in Sweden, or to have subsided very slowly, as in Greenland. That these same movements, whether ascending or descending, have continued for ages in the same direction has been established by histo- rical or geological evidence. Thus, we find on the opposite coasts of Sweden, that brackish water deposits, like those now forming in the Baltic, occur on the eastern side; and upraised strata filled with purely marine shells, now proper to the ocean, on the western coast. Both of these have been lifted up to an elevation of several hundred feet above high-water mark. The rise within the historical period has not amounted to many yards, but the greater extent of antecedent upheaval is proved by the occurrence in inland spots, several hundred feet high, of deposits filled with fossil shells of species now living either in the ocean or the Baltic. To detect proofs of slow and gradual subsidence must in general be more difficult; but the theory which accounts for the form of circular coral reefs and lagoon islands, and which wil be explained in the concluding chapter of this work, will satisfy the reader that there are spaces on the globe, several thousand miles in cireumference, throughout which the downward movement has predominated for ages, and yet the land has never, in a single instance, gone down suddenly for several hundred feet at once. Yet geology demonstrates that the persistency of subterranean movements in one direction has not been perpetual throughout all past time. There have | | | | | | | | | a | —— Al, LN SS, Rn Cu. X1V.] SUBTERRANEAN MOVEMENTS. 815 been great oscillations of level by which a surface of dry land has been submerged to a depth of several thousand feet, and then at a period long subsequent raised again and made to emerge. Nor have the regions now motionless been always at rest; and some of those which are at present the theatres of reiterated earthquakes have formerly enjoyed a long con- tinuance of tranquillity. But although disturbances have ceased after having long prevailed, or have recommenced after a suspension for ages, there has been no universal dis- ruption of the earth’s crust or desolation of the surface since times the most remote. The non-occurrence of such a general convulsion is proved by the perfect horizontality now retained by some of the most ancient fossiliferous strata throughout wide areas. That the subterranean forces have visited different parts of the globe at successive periods, is inferred chiefly from the unconformability of strata belonging to groups of different ages. Thus, for example, on the borders of Wales and Shrop- shire, we find the slaty beds of the ancient Silurian system curved and vertical, while the beds of the overlying carboni- ferous shale and sandstone are horizontal. All are agreed, that in such a case the older set of strata had suffered great dislocation before the deposition of the newer or carboniferous beds, and that these last have never since been violently fractured, nor have ever been bent into folds, whether by sud- den or continuous lateral pressure. On the other hand, the more ancient or Silurian group suffered only a local derange- ment, and neither in Wales nor elsewhere are all the rocks of that age found to be in a curved or vertical position. . In various parts of Europe, for example, and particularly near Lake Wener in the south of Sweden, and in many parts of Russia, the Silurian strata maintain the most perfect hori- zontality ; and a similar observation may be made respecting limestones and shales of like antiquity in the great lake dis- trict of Canada and the United States. They are still as flat and ‘horizontal as when first formed; yet since their origin not only have most of the actual mountain-chains been uplifted, but the very rocks of which those mountains are composed have been formed. 316 UNIFORMITY OF CHANGE. [Cu. XIV, It would be easy to multiply instances of similar uncon- formability in formations of other ages; but a few more will suffice. The Coal-measures before alluded to as horizontal] on the borders of Wales are vertical in the Mendip Hills in Somersetshire, where the overlying beds of the New Red Sandstone are horizontal. Again, in the Wolds of Yorkshire the last-mentioned sandstone supports on its curved and in- clined beds the horizontal Chalk. The Chalk again is vertical on the flanks of the Pyrenees, and the tertiary strata repose unconformably upon it. As almost every country supplies illustrations of the same phenomena, they who advocate the doctrine of alternate periods of disorder and repose may appeal to the facts above described, as proving that every district has been by turns convulsed by earthquakes and then respited for ages from convulsions. But so it might with equal truth be affirmed that every part of Europe has been visited alternately by winter and summer, although it has always been winter and always summer in some part of the planet, and neither of these seasons has ever reigned simultaneously over the entire globe. They have been always shifting about from place to place; but the vicissitudes which recur thus annually in a single spot are never allowed to interfere with the invariable uniformity of seasons throughout the whole planet. So, in regard to subterranean movements, the theory of the perpetual uniformity of the force which they exert on the earth’s crust is quite consistent with the admission of their alternate development and suspension for long and indefi- nite periods within limited geographical areas. If, for reasons before stated, we assume a continual extinc- tion of species and introduction of others into the globe, it will then follow that the fossils of strata formed at two dis- tant periods on the same spot, will differ even more certainly than the mineral composition of those strata. For rocks of the same kind have sometimes been reproduced in the same district after a long interval of time; whereas all the evi- dence derived from fossil remains is in favour of the opinion that species which have once died out have never been reproduced. The submergence, then, of land must be often Cu. XIV. SUBTERRANEAN MOVEMENTS. 317- attended by the commencement of a new class of sedimentary deposits, characterised by a new set of fossil animals and plants, while the reconversion of the bed of the sea into land may arrest at once and for an indefinite time the formation of geological monuments. Should the land again sink, strata will again be formed; but one or many entire revolutions in animal or vegetable life may have been completed in the interval. As to the want of completeness in the fossiliferous series, which may be said to be almost universal, we have only to reflect on what has been already said of the laws governing sedimentary deposition, and those which give rise to fluctua- tions in the animate world, to be convinced that a very rare combination of circumstances can alone give rise to such a su- perposition and preservation of strata, as will bear testimony to the gradual passage from one state of organic life to another. To produce such strata nothing less will be requisite than the fortunate coincidence of the following conditions: first, a never-failing supply of sediment in the same region through- out a period of vast duration ; secondly, the fitness of the deposit in every part for the permanent preservation of im- bedded fossils; and, thirdly, a gradual subsidence to prevent the sea or lake from being filled up and converted into land. Tt will appear in the chapter on coral reefs,* that, in cer- tain parts of the Pacific and Indian Oceans, most of these conditions, if not all, are complied with, and the constant growth of coral, keeping pace with the sinking of the bottom of the sea, seems to have gone on so slowly, for such indefi- nite periods, that the signs of a gradual change in organic life might probably be detected in that quarter of the globe, if we could explore its submarine geology. Instead of the erowth of coralline limestone, let us suppose, in some other place, the continuous deposition of fluviatile mud and sand, such as the Ganges and Brahmapootra have poured for thousands of years into the Bay of Bengal. Part of this bay, although of considerable depth, might at length be filled up before an appreciable amount of change was effected in the fish, mollusca, and other inhabitants of the sea and neigh- * See last chapter of Vol. II. of this Work. 318 CAUSES OF BREAKS IN [Cu. XIv, bouring land. But, if the bottom be lowered by sinking at the same rate that it is raised by fluviatile mud, the bay can never be turned into dry land. In that case one new layer of matter may be superimposed upon another for a thickness of many thousand feet, and the fossils of the inferior beds may differ greatly from those entombed in the uppermost, yet every intermediate gradation may be indicated in the pas- sage from an older to a newer assemblage of species. Grant- ing, however, that such an unbroken sequence of monuments may thus be elaborated in certain parts of the sea, and that the strata happen to be all of them well adapted to preserve the included fossils from decomposition, how many accidents must still concur before these submarine formations will be laid open to our investigation! The whole deposit must first be raised several thousand feet, in order to bring into view the very foundation; and during the process of exposure the superior beds must not be entirely swept away by denu- dation. In the first place, the chances are nearly as three to one against the mere emergence of the mass above the waters, because nearly three-fourths of the globe are covered by the ocean. But if it be upheaved and made to constitute part of the dry land, it must also, before it can be available for our instruction, become part of that area already surveyed by geologists; and this area comprehends perhaps less than a tenth of the whole earth. In this small fraction of land already explored, and still very imperfectly known, we are required to find a set of strata, originally of limited extent, and probably much lessened by subsequent denudation. Yet it is precisely because we do not encounter at every step the evidence of such gradations from one state of the organic world to another, that so many geologists have em- braced the doctrine of great and sudden revolutions in the history of the animate world. Not content with simply availing themselves, for the convenience of classification, of those gaps and chasms which here and there interrupt the continuity of the chronological series, as at present known, they deduce, from the frequency of these breaks in the chain of records, an irregular mode of succession in the events | | | | | | | Cu. XIV.] THE SEQUENCE OF FORMATIONS. 319 themselves, both in the organic and inorganic world. But, besides that some links of the chain which once existed are now clearly lost and others concealed from view, we have good reason to suspect that it was never complete originally. It may undoubtedly be said that strata have been always forming somewhere, and therefore at every moment of past time nature has added a page to her archives; but, in refer- ence to this subject, it should be remembered that we can never hope to compile a consecutive history by gathering together monuments which were originally detached and scattered over the globe. For as the species of organic beings con- temporaneously inhabiting remote regions are distinct, the fossils of the first of several periods which may be preserved in any one country, as in America, for example, will have no connection with those of a second period found in India, and will therefore no more enable us to trace the signs of a gradual change in the living creation, than a fragment of Chinese history will fill up a blank in the political annals of EKurope. The absence of any deposits of importance containing recent shells in Chili, or anywhere on the western coast of South America, naturally led Mr. Darwin to the conclusion that ‘ where the bed of the sea is either stationary or rising, circumstances are far less favourable than where the level is sinking to the accumulation of conchiferous strata of sufficient thickness and extension to resist the average vast amount of denudation.”* In like manner the beds of superficial sand, clay and gravel, with recent shells on the coasts of Norway and Sweden, where the land has risen in Post-tertiary times, are so thin and scanty as to incline us to admit a similar proposition. We may in fact assume that in all cases where the bottom of the sea has been undergoing continuous elevation, the total thickness of sedimentary matter accumu- lating at depths suited to the habitation of most of the species of shells can never be great, nor can the deposits be thickly covered by superincumbent matter, so as to be consolidated by pressure. When they are upheaved, therefore, the waves on the beach will bear down and disperse the loose materials ; * Darwin’s 8. America, pp. 186, 139. 320 CONCLUDING REMARKS ON [Cu. XIV, whereas, if the bed of the sea subsides slowly, a mass of strata, containing abundance of such species as live at moderate depths, may be formed and may increase in thick- ness to any amount. It may also extend horizontally over a broad area, as the water gradually encroaches on the subsid- ing land. Hence it will follow that great violations of continuity in the chronological series of fossiliferous rocks will always exist, and the imperfection of the record, though lessened, will never be removed by future discoveries. For not only will no deposits originate on the dry land, but those formed in the sea near land, which is undergoing constant upheaval, will usually be too slight in thickness to endure for ages. In proportion as we become acquainted with larger geo- graphical areas, many of the gaps, by which a chronological table, like that given at page 139, is rendered defective, will be removed. We were enabled by aid of the labours of Prof. Sedgwick and Sir Roderick Murchison, to inter- calate, in 1838, the marine strata of the Devonian period, — with their fossil shells, corals and fish, between the Silurian and Carboniferous rocks. Previously the marine fauna of these last-mentioned formations wanted the connecting links which now render the passage from the one to the other much less abrupt. So the hiatus subsisting in England be- tween the Permian and Liassic strata, is filled up on the con- tinent by the marine Trias of Germany where the Muschel- kalk, as well as the St. Cassian beds occur, both of them rich in marine fossils. The Upper Miocene has no represen- tative in England, but in France, Germany, and Switzerland, it constitutes a most instructive link between the living creation and the middle of the great Tertiary period. Still we must expect, for reasons before stated, that chasms will for ever continue to occur, in some parts of our sedimentary series. Concluding remarks on the consistency of the theory of gradual change, with the ewistence of great breaks im the series.—To return to the general argument pursued in this chapter, it is assumed, for reasons above explained, that a slow change of species is in simultaneous operation every- i tin to a-_- es — o> fe a Bee: cee ~ ag ae | Cu. XIV.] THE SEQUENCE OF FORMATIONS. 39] where throughout the habitable surface of sea and land; whereas the fossilisation of plants and animals is confined to those areas where new strata are produced. These areas, as we have seen, are always shifting their position, so that the fossilising process, by means of which the comme- moration of the particular state of the organic world, at any given time, is affected, may be said to move about , Visiting and revisiting different tracts in succession. To make still more clear the supposed ee of this machinery, I shall compare it to a somewhat analogous case that might be imagined to occur in the history of human affairs. Let the mortality of the population of a large country represent the successive extinction of species, and the births of new individuals the introduction of new species. While these fluctuations are gradually taking place everywhere, sup- pose commissioners to be appointed to visit each province of the country in succession, taking an exact account of the number, names, and individual peculiarities of all the in- habitants, and leaving in each district a register containing a record of this information. If, after the completion of one census, another is immediately made on the same plan, and then another, there will, at last, be a series of statistical documents in each province. When those belonging to any one province are arranged in chronological order, the con- tents of such as stand next to each other will differ according to the length of the intervals of time between the taking of each census. If, for example, there are sixty provinces, and all the registers are made in a single year and renewed annually, the number of births and deaths will be so small, in proportion to the whole of the inhabitants, during the interval between the compiling of two consecutive docu- ments, that the individuals described in such documents will be nearly identical; whereas, if the survey of each of the Sixty provinces occupies all the commissioners for a whole year, so that they are unable to revisit the same place until the expiration of sixty years, there will then be an almost entire discordance between the persons enumerated in two consecu- tive registers in the same province. There are, undo ubtedly other causes besides the mere quantity of time, which orn VOL. I. b 399 CONCLUDING REMARKS ON (Cu. XIV, augment or diminish the amount of discrepancy. Thus, at some periods a pestilential disease may have lessened the average duration of human life, or a variety of circumstances may have caused the births to be unusually numerous, and the population to multiply ; or, a province may be suddenly colo- nised by persons migrating from surrounding districts. These exceptions may be compared to the accelerated rate of fluctuation in the fauna and flora of a particular region, in which the climate and physical geography may be under- going an extraordinary degree of alteration. But I must remind the reader, that the case above pro- posed has no pretensions to be regarded as an exact parallel to the geological phenomena which I desire to illustrate ; for the commissioners are supposed to visit the different pro- vinces in rotation; whereas the commemorating processes by which organic re mains become fossilised, although they are always shifting from one area to the other, are yet very irregular in their movements. They may abandon and revisit many spaces again and again, before they once approach another district; and, besides this source of irregularity, it may often happen that, while the depositing process is sus- pended, denudation may take place, which may be compared to the occasional destruction by fire or other causes of some of the statistical documents before mentioned. It is evident that, where such accidents occur, the want of continuity in the series may become indefinitely great, and that the monu- ments which follow next in succession will by no means be equidistant from each other in point of time. If this train of reasoning be admitted, the occasional dis- tinctness of the fossil remains, in formations immediately in contact, would be a necessary consequence of the existing laws of sedimentary deposition and subterranean movement, accom- panied by a constant mortality and renovation of species. As all the conclusions above insisted on are directly opposed to opinions still popular, I shall add another comparison, in the hope of preventing any possible misapprehension of the argument. Suppose we had discovered two buried cities at the foot of Vesuvius, immediately superimposed upon each other, with a great mass of tuff and lava intervening, just as Cu. XIV.] THE SEQUENCE OF FORMATIONS. 393 Portici and Resina, if now covered with ashes, would overlie Herculaneum. An antiquary might possibly be entitled to infer, from the inscriptions on public edifices, that the in- habitants of the inferior and older city were Greeks, and those of the modern towns Italians. But he would reason very hastily if he also concluded from these data, that there had been a sudden change from the Greek to the Italian lan euace in Campania. But if he afterwards found three buried cities, one above the other, the intermediate one being Roman, while, as in the former example, the lowest was Greek and the uppermost Italian, he would then perceive the fallacy of his former opinion, and would begin to suspect that the catastrophes, by which the cities were inhumed, might have no relation whatever to the fluctuations in the language of the inhabitants: and that, as the Roman tongue had evi- dently intervened between the Greek and Italian, so many other dialects may have been spoken in succession, and the passage from the Greek to the Italian may have been very gradual; some terms growing obsolete, while others were introduced from time to time. If this antiquary could have shown that the volcanic paroxysms of Vesuvius were so governed as that cities should be buried one above the other, just as often as any variation occurred in the language of the inhabitants, then, indeed, the abrupt passage from a Greek to a Roman, and from a Roman to an Italian city, would afford proof of fluctuations no less sudden in the language of the people. So, in Geology, if we could assume that it is part of the plan of Nature to preserve, in every region of the globe, an unbroken series of monuments to commemorate the vicissi- tudes of the organic creation, we might infer the sudden ex- tirpation of species, and the simultaneous introduction of others, as often as two formations in contact are found to in- clude dissimilar organic fossils. ut we must shut our eyes to the whole economy of the existing causes, aqueous, igneous, and organic, if we fail to perceive that such is not the plan of Nature. I shall now conclude the discussion of a question with which we have been occupied since the beginning of the fifth y2 324 CONCLUDING REMARKS ON (Cu. XIV. chapter; namely, whether there has been any interruption, from the remotest periods, of one uniform system of change in the animate and inanimate world. We were induced to uter into that enquiry by reflecting how much the progress of opinion in Geology had been influenced by the assumption that the analogy was slight in kind, and still more slight in degree, between the causes which produced the former revo- lutions of the globe, and those now in every-day operation. It appeared clear that the earlier geologists had not only a scanty acquaintance with existing changes, but were singu- larly unconscious of the amount of their ignorance. With the presumption naturally inspired by this unconsciousness, they had no hesitation in deciding at once that time could never enable the existing powers of nature to work out changes of ercat magnitude, still less such important revolutions as those which are brought to light by Geology. They, therefore, felt themselves at liberty to indulge their imaginations in cuessing at what might be, rather than enquiring what is; im other words, they employed themselves in conjecturing what might have been the course of Nature at a remote period, rather than in the investigation of what was the course of Nature in their own times. It appeared to them far more philosophical to speculate on the possibilities of the past, than patiently to explore the realities of the present; and having invented theories under the influence of such maxims, they were consistently unwill- ing to test their validity by the criterion of their accordance with the ordinary operations of Nature. On the contrary, the claims of each new hypothesis to credibility appeared enhanced by the great contrast, in kind or intensity, of the causes referred to and those now in operation. Never was there a dogma more calculated to foster indo- lence, and to blunt the keen edge of curiosity, than this ssumption of the discordance between the ancient and exist- ing causes of change. It produced a state of mind unfavour- able in the highest degree to the candid reception of the evidence of those minute but incessant alterations which ~ every part of the earth’s surface is undergoing, and by which the condition of its living inhabitants is continually made to al —$ rT Cu. XIV.] THE SEQUENCE OF FORMATIONS. 895 vary. The student, instead of being encouraged with the hope of interpreting the enigmas presented to him in the earth’s structure,—instead of being prompted to undertake laborious enquiries into the nature al history of the organic world, and the complicated effects of the igneous and aqueous causes now in operation, was taught to despond from the first. Geology, it was affirmed, sould never rise to the rank of an exact science,—the greater number of phenomena must for ever remain inexplicable, or only be paren y elucidated by ingenious conjectures. Even the mystery which invested the subject was said to constitute one of its principal charms, affording, as it did, full scope to the fancy to indulge in a boundless field of speculation. The course directly opposed to this method of philoso- phising consists in an earnest and patient enquiry, how far geological appearances are reconcilable with the effect of changes now in progress, or which may be in progress in regions inaccessible to us, and of which the re eality is attested by volcanos and subterranean movements. It also endea- vours to estimate the age? ‘egate result of ordinary operations multiplied by time, and cher ishes a sanguine hope that the resources to be derived from observation and experiment, or from the study of Nature such as she now is, are very far from ing exhausted. For this reason all fice are rejected which involve the assumption of sudden and violent catas- trophes and revolutions of the whole ea rth, and its inhabi- tants,—theories which are restrained by no reference to exist- ing analogies, and in which a desire is manifested to cut, rather than patiently to untie, the Gordian knot. We have now, at least, the advantage of knowing, from experience, that an opposite method has always put geolo- gists on the road that leads to truth, —suggesting views which, although imperfect at first, have been found ca upable of im- provement, until at last adopted by universal consent ; while the method of speculating on a former distinct state of things and causes, has led invariably to a multitude of contra vdictory systems, which have been overthrown one after the othe ets = have been found incapable of modification,—and which have often required to be precisely reversed. o om 326 THE SYSTEM OF TERRESTRIAL CHANGES. (Ca: XTy; The remainder of this work will be devoted to an investi- gation of the changes now going on in the crust of the earth and its inhabitants. ‘The importance which the student will attach to such researches will mainly depend on the degree of confidence which he feels in the principles above expounded, If he firmly believes in the resemblance or identity of the ancient and present system of terrestrial changes, he will regard every fact collected respecting the causes in diurnal action as affording him a key to the interpretation of some mystery in the past. Events which have occurred at the most distant periods in the animate and inanimate world, will be acknowledged to throw light on each other, and the deficiency of our information respecting some of the most obscure parts of the present creation will be removed. For as, by studying the external configuration of the existing land and its inhabitants, we may restore in imagination the appearance of the ancient continents which have passed away, so may we obtain from the deposits of ancient seas and lakes an insight into the nature of the subaqueous processes now in operation, and of many forms of organic life, which though now existing, are veiled from sight. Rocks, also, produced by subterranean fire in former ages, at great depths in the bowels of the ee present us, when upraised by adual mov Lela and exposed to the light of heaven, with an image of those changes which the deep-seated voleano may now occasion in the nether regions. Thus, although we are mere sojourners on the surface of the planet, chained to y mere point in space, enduring but for a moment of time, the human mind is not only enabled to number worlds bey ond the unassisted ken of mortal eye, but to trace the events of indefinite ages before the creation of our race, and is not even withheld from penetrating into the dark secrets of the ocean, or the interior of the solid globe; free, like the spirit Ee ma pag By 1 ° ° . which the poet described as animating the universe, —-—_——]re per omnes Terrasque, tractusque maris, ceelumque profundum. bo “I © ' BOOK II. CHANGES IN THE INORGANIC WORLD NOW IN PROGRESS. CHAPTER XV. AQUEOUS CAUSES. DIVISION OF THE SUBJECT INTO CHANGES OF THE ORGANIC AND INORGANIC INORGANIC CAUSES OF CHANGE DIVIDED INTO AQUEOUS AND IGNEOUS RAIN-PRINTS WORLD —AQUEOUS CAUSES FIRST CONSIDERED—FALL OF RAIN—RECENT YROL AND SWISS ALPS IN MUD —EARTH-PYRAMIDS FORMED BY RAIN IN THE T = ARF’S TOWER NEAR VIESCH—DES YING AND TRANSPORTING POWER OF RUNNING WATER—NEWLY-FORMED VALLE xYS IN GEORGIA—SINUOSITIES OF RIVERS—TWO STREAMS WHEN UNITED DO NOT OCCUPY A BED OF DOUBLE SURFACE — INUNDATIONS IN SCOTLAND—FLOODS CAUSED BY LANDSLIPS IN THE WHITE MOUNTAINS—BURSTING OF A LAKE IN SWITZERLAND—DEVASTA~ EXCAVATIONS IN THE LAVAS OF ETNA TIONS CAUSED BY THE ANIO AT TIVOLI > 2 a . % P re a } face (see fio. 16, left side). They occasionally pass under the j=] Cu. XV.] RECENT RAIN-PRINTS. 335 middle of a rain-mark, having been formed subsequently. | Sometimes the worms have dived beneath the surface, and then reappeared. All these appearances, both of rain-prints | and worm-tracks, are of great geological interest, as their exact counterparts are seen in rocks of various ages even in | formations of very high antiquity.* Small cavities, often corresponding in size to those produced by rain, are also caused by air-bubbles rising up through sand or mud; but these differ in character from rain-prints, being usually deeper than t | they are wide, and having their sides steeper. ‘These, indeed, } are occasionally vertical, or overarching, the opening at the top being narrower than the pit below. In their mode, also, of mutual interference they are unlike ‘ain-prints.t | In consequence of the effects of mountains in cooling j currents of moist air, and causing the condensation of aqueous | yapour in the manner above described (page 329) it follows that in every country, as a general rule, the more elevated | regions become perpetual reservoirs of water, which descends and irrigates the lower valleys and plains. The largest quan- tity of water is first carried to the highest region, and made to descend by steep declivities towards the sea ; so that it ac- quires superior velocity, and removes more soil, than it would | do if the rain had been distributed over the plains and moun- tains equally in proportion to their relative areas. ‘The water | is also made by these means to pass over the greatest dis- tances before it can regain the sea. Earth-pyramids or stone-capped pillars of Botzen in the Tyrol.—It is not often that the effects of the denuding action | of rain can be studied separately or as distinct from those of running water. There are, however, several cases in the Alps, | and especially in the Tyrol near Botzen, which present a marked exception to this rule, where columns of indurated mud, varying in height from twenty to a hundred feet, and usually capped by a single stone, have been separated by rain from the terrace of which they once formed a part, and now stand at various levels on the steep slopes bounding narrow * See Elements of Geology, Index Quart. Journ. Geol. Soe. 1851, vol. vii. Rain-prints. p. 239 See Lyell on recent and fossil rains. 336 EARTH-PILLARS (Ca. XV} valleys. Botzen is situated on the Hisack, two miles above the junction of that river with the Adige, and is 836 feet ee the sea. It is in the valleys of two tributary streams which join the Hisack.a short distance above Botzen, that the phatipal eroups of pillars occur. Those, nearest to the town and situated about a mile and a half to the N.K. of* it, are in the ravine of the Katzenbach, elevated about 1,700 feet above Botzen; they are the most remarkable of any for their number, size, and beauty. The other pillars occur in the ravine of the Finsterbach, near Klobenstein, at the height of about 2,200 feet above Botzen, and three and a half miles N.E. of that town. These I shall describe more particularly, as Sir John F. W. Herschel has had the kind- ness to enable me to give an accurate representation of them drawn by himself in 1824, by the aid of the Camera Lucida. T have not room to give his entire drawing, but have selected a part of it, representing the entrance of a tributary ravine into the main valley. (See Plate Il.) In such smaller ravines, the same feat wes which are seen on the boundary COAST——ESTUARY OF T MES— GOODWIN SANDS—COAST OF KENT——-FORMATION OF E TH STRAITS OF DOVER-—-SOUTH COAST OF ENGLAND — SUSSEX — HANTS—DORSET —PORTLAND—ORIGIN OF THE CHESIL BANK—-TORBAY—ST. MICHAEL S$ MOUNT, CORNWALL-——COAST OF BRITTANY. Aurnoven the movements of great bodies of water, termed tides and currents, are in general due to very distinct causes, their effects cannot be studied separately ; for they produce, by their joint action, aided by that of the waves, those changes which are objects of geological interest. These forces may be viewed in the same manner as we before con- sidered rivers, first, as employed in destroying portions of the solid crust of the earth, and removing them to other places ; secondly, as reproductive of new strata. Tides.—It would be superfluous at the presént day to offer any remarks on the cause of the tides. They are not percep- tible in lakes or in most inland seas; in the Mediterranean even, deep and extensive as is that sea, they are scarcely sen- sible to ordinary observation, their effects being quite sub- ordinate to those of the winds and currents. In some places, however, as in the Straits of Messina, there is an ebb and flow to the amount of two feet and upwards; at Naples and at the Huripus, of twelve or thirteen inches; and at Venice, 494 TIDES. MGs ie according to Rennell, of five feet.* In the Syrtes, also, of the ancients, two wide shallow gulfs, which penetrate very far within the northern coast of Africa, between Carthage and Cyrene, the rise is said to exceed five feet.t ' Tn islands remote from any continent, the ebb and flow of the ocean is very slight, as at St. Helena, for example, where it is rarely above three feet.{ In any given line of coast, the tides are greatest in narrow channels, bays, and estuaries, and least in the intervening tracts where the land is promin- ent. Thus, at the entrance of the estuary of the Thames and Medway, the rise of the spring tides is eighteen feet; but when we follow our eastern coast from thence northward, to- wards Lowestoff and Yarmouth, we find a gradual diminution, until, at the places last mentioned, the highest rise is only seven or eight feet. From this point there begins again to be an increase, so that at Cromer, where the coast again re- tires towards the west, the rise is sixteen feet; and towards the extremity of the gulf called ‘the Wash,’ as at Lynn and in Boston Deeps, it is from twenty-two to twenty-four feet, and in some extraordinary cases twenty-six feet. From thence again there is a decrease towards the north, the ele- vation at the Spurn Point being from nineteen to twenty feet, and at Flamborough Head and the Yorkshire coast from four- teen to sixteen feet.$ At Milford Haven in Pembrokeshire, at the mouth of the Bristol Channel, the tides rise thirty-six feet; and at King- Road near Bristol, forty-two feet.. At Chepstow on the Wye, a small river which opens into the estuary of the Severn, they reach fifty feet and sometimes sixty-nine, and even seventy- two feet.|| A current which sets in on the French coast, to the west of Cape La Hague, becomes bent up by Guernsey, Jersey, and other islands, till the rise of the tide is from twenty to forty-five feet, which last height it attains at Jersey, and at St. Malo, a seaport of Brittany. The tides in * Geog. of a vol. i. p. 331. § The heights of these tides were if Ibid. p p. 328 given me by the late Capti iin Hewett, t ae ae et Courans, vol. 11. Re p. 2 . F. Fallows, Quart. Journ. of || On the authority of Admiral Sir F. Scienee, ; March 1829. Beaufort, R.N. tty ——— ail in SS ee Cu. XX.] CURRENTS. 4 95 the Basin of Mines, at the head of the Bay of Fundy in Nova Scotia, rise to the height of seventy feet. There are, however, some coasts where the tides seem to offer an exception to the rule above mentioned ; for while there is scarcely any rise in the estuary of the Plata in South America, there is an extremely high tide on the open coast of Patagonia, farther to the south. Yet even in this region the tides reach their greatest elevation (about fifty feet) in the Straits of Magellan, and so far at least they conform to the general rule. Causes of currents—That movements of no inconsiderable magnitude should be impressed on a wide expanse of ocean, by winds blowing for many months in one direction, may easily be conceived, when we observe the effects produced in ur own seas by the temporary action of the same cause. It is well known that a strong south-west or north-west wind invariably raises the tides to an unusual height along the west coast of England and in the Channel ; and that a north- west wind of any continuance causes the Baltic to rise two feet and upwards above its ordinary level. Smeaton ascer- tained by experiment, that in a canal four miles in length, the water was kept up four inches higher at one end than at the other merely by the action of the wind along the canal ; and the late Major Rennell informs us that a large piece of water, ten miles broad, and generally only three feet deep, has, by a strong wind, had its waters driven to one side, and sustained so as to become six feet deep, while the windward side was laid dry.* As water, therefore, he observes, when pent up so that it cannot escape, acquires a higher level, so, in a place where wt can escape, the same operation produces a current ; and this current will extend to a greater or less distance, according to the force by which it is produced. The same writert has divided currents according to their origin into drift- and stream-currents ; the former being due to constant and preva- lent winds impelling the surface water to leeward until it meets with some obstacle which stops it and occasions an * Rennell on the Channel Current. the Atlantic Ocean, page 21. London, t Investigation of the Currents of 1832. 496 CURRENTS. (Cu. XX, accumulation, this accumulation giving rise to a stream-cur- rent. The obstacle may be either land or banks or a stream- current already formed. A stream-current may be of any bulk, or depth, or velocity; a drift-current is shallow and rarely exceeds in velocity the rate of half a mile an hour, Currents flowing alternately in opposite directions are occasioned by the rise and fall of the tides. The effect of this cause, as we shall see in the sequel, is most striking in estuaries and channels between islands. A third cause of oceanic currents is evaporation by solar heat. Of this the current setting in from the Atlantic through the Straits of Gibraltar into the Mediterranean is a good example, which will be fully considered in the next chapter. It must happen in many other parts of the world, that large quantities of water raised from one tract of the ocean by solar heat, are carried to some other where the vapour is condensed and falls in the shape of rain, and the surface waters thus increased will give rise to currents as they flow back again to restore equilibrium. These considerations naturally lead to the enquiry whether the level of those seas out of which currents flow is higher than that of seas into which they flow. If not, the effect must be immediately equalised by under-currents or counter- currents. Arago is of opinion that, so far as observations have gone, there are no exact proofs of any such difference of level. It was inferred from the measurements of M. Lepére, that the level of the Mediterranean, near Alexandria, was lower by 26 feet 6 inches, than the Red Sea near Suez at low water, and about 30 feet lower than the Red Sea at the same place at high water,* but the late Mr. Robert Stephenson affirmed, as the result of a more recent survey, that there is no difference of level between the two seas.t It was formerly imagined that there was an equal, if not greater, diversity in the relative levels of the Atlantic and Pacific, on the opposite sides of the Isthmus of Panama But the levellings carried across that isthmus by Captain Lloyd, in 1828, to ascertain the relative height of the Pacific * Ann. du Bureau des Long. 1836. Steam Communication with India, July f~ Second Parliamentary Report on 1861. Cu, XX.] CAUSES OF CURRENTS. 497 Ocean at Panama, and of the Atlantic at the mouth of the river Chagres, have shown, that the difference of mean level between those oceans is not considerable, and, contrary to expectation, the difference which does exist is in favour of the greater height of the Pacific. A fourth cause of currents is the discharge into the sea of large bodies of fresh water by the great rivers of the globe, which, as General Sabine remarks, sometimes preserve their original direction and flow with a very slowly diminishing velocity for several hundred miles over the surface of the ocean. Thus he found in the year 1822, that the river Amazons preserved a velocity of nearly three miles an hour, at a distance of upwards of 300 miles from its mouth, its original direction being scarcely altered, and the fresh water having only become partially mixed with that of the ocean. The river Plate, says Rennell, has still a velocity cf a mile an hour, and a breadth of more than 800 miles, at a distance of not less than 600 miles from its mouth. The existence of another or a fifth class of currents was first suspected when it was observed that the tropical seas had a much lower temperature at great depths than at the surface. Whenever in the arctic or antarctic regions the superficial waters are cooled, provided they do not ap- proach the freezing point, they are rendered heavier by con- densation and fall to the bottom. Lighter water then rises to take their place and by this circulation of ascending and descending currents in high latitudes, the inferior parts of the sea become heavier than the adjoining parts of the temperate and tropical ocean at corresponding levels. In that case, if there be a free communication, if no continuous shoal or chain of submarine mountains divide the polar from the equatorial basins, a horizontal movement will arise by the flowing of the colder water from the poles to the equator, and there will be a reflix of warmer superficial water from the equator to the poles. A. well-known experiment has been adduced to elucidate this mode of action in explanation of the ‘trade winds. * Ifa long trough, divided in the middle ee gel 2 tn ree On aor of series, vol. i., and Appendix to Daniell’s 8, g of Voy. second y. Won: 1, Meteorolog KK 498 CAUSES OF CURRENTS. (Cu. XX, by a sluice or partition, have one end filled with water and the other with quicksilver, both fluids will remain quiet so long as they are divided; but when the sluice is drawn u : the heavier fluid will rush along the bottom of the trough, while the lighter, being displaced, will rise, and, flowing in an opposite direction, spread itself at the top. We have already seen, p. 244, that a cold current from the north having a temperature of only 40° Fahr., passes in lat. 4.0°30’N. under the Gulf-stream, which, having a temperature of 80° Fahr., runs above it in exactly an opposite direction. A striking example will be given in the next chapter, p. 562, of the effect of a submarine barrier in preventing the lower parts of an inland sea from being cooled by an under-current from the neighbouring ocean. One of the chief oceanic currents is that which flows through the Mozambique Chan- nel, and there skirts the south-east coast of Africa, having a breadth of ninety miles and a velocity of between two and four miles an hour. On reaching the Cape, it is turned westward by the Lagullas, a great shoal or rather a submerged chain of mountains, which, rising from a deep ocean, comes within 100 fathoms of the surface. The deflection of this current, says Rennell, proves that it is more than 100 fathoms deep, otherwise the main body of it would pass across the bank instead of being deflected westward, so as to flow round the Cape of Good Hope. It is then joined by a cur- rent from the south or from antarctic latitudes, and, con- tinuing its course, takes a northerly direction along the western coast of Africa, till it reaches the Bight or Bay of Benin. There it is turned westward, partly by the form of the coast and partly perhaps by meeting the Guinea current, which runs from the north into the same great bay. From the centre of this bay proceeds what is called the equatorial current of the Atlantic, having a width of from 160 to 450 ss that nautical miles, and holding a westerly course acro ocean which it traverses from the coast of Guinea to that of Brazil. The whole length is said to be about 4,000 geogra- phical miles, and its velocity from twenty-five to § nine miles per day, the mean rate being about thirty miles. On approaching the N.E. promontory of South America, eventy- Cu. XX.] CAUSES OF CURRENTS. 499 called Cape St. Roque, it divides itself into two parts, one portion of which pursues a southerly course along the coast of Brazil, while the principal part of it flows westward, and skirting the coast of Guiana, is reinforced by the waters of the Amazons and Orinoco, which impart to it an accelerated speed. After passing the island of Trinidad, it expands and contributes in some degree to raise the waters of the Carri- bean Sea and Gulf of Mexico, which are also Supposed. to be heaped up by the blowing of the north-east trade winds—a combination of circumstances which gives rise to the Gulf- stream. The last-mentioned current has already been alluded to in the twelfth chapter, p. 244, as moderating the cold ofa large part of the northern hemisphere. s Sia ee) 4 of Tut INDIAN ARCHIPELAGO, d and 3 p. Paciric OcEAN. From C. Darwin’s ‘ Coral Reefs,’ 1842. © os 5 end E 2 ~ mh ms . am 5 Re * p= | o ® Vanikorol: Mariana [? 2 or o g ° eh 7 = pad od “4 fal 8 : 8 ate 4 > g we g nt ~ XS Sa eee Pry sili feu for eh somo ve ia | oy OAR os ty wes eS yy if Wi) ¥ = = ALIAS SE OST RAN eee a a 2 io) op x co | ~ — e wm so = x | mM ond raat © ot ° 12) fa io) mn = S ° pee Los] op = Sion i=] a bs] ~~ 8 ° o o o S oO oO = n 2 =) a SH ° n o o 4 rains of active voleanos. Active volcanos. S ¢ EZ Areas of subsidence containing atolls or coral islands with lagoons. t s 2 9) a fe) b 0) > = ‘p 19) Cs) G4 fe) n I ort @ H 5. @ Active volcanos. C4. XXII] OF VOLCANIC REGIONS. 587 terruptions, throughont a space of between sixty and seventy degrees of latitude to the Moluccas, where it sends off a branch to the south-east, while the principal train continues westerly through Sumbawa and Java to Sumatra, and then +n a north-westerly direction to the Bay of Bengal.* This yoleanic line, observes Von Buch, may be said to follow throughout its course the external border of the continent of Asia; while the branch which has been alluded to as striking south-east from the Moluccas, passes from New Guinea to New Zealand, conforming, though somewhat rudely, to the outline of Australia.t The connection, however, of the New Guinea volcanos with the line in Java (as laid down in Von Buch’s map) is not clearly made out. By consulting Darwin’s map of coral reefs and active voleanos,t{ the reader will see that we might almost with equal propriety include the Mariana and Bonin volcanos in a band with New Guinea. Or if we allow so much latitude in framing zones of volcanic action, we must also suppose the New Hebrides, Salomon Isles, and New Ireland to con- stitute one line (see map, fig. 59, p. 586). The northern extremity of the volcanic region of Asia, as described by Von Buch, is on the borders of Cook’s Inlet, north-east of the Peninsula of Alaska, where one volcano, in about the sixtieth degree of latitude, is said to be 14,000 feet high. In Alaska itself are cones of vast height, which have been seen in eruption, and which are covered for two thirds of their height downwards with perpetual snow. The summit of the loftiest peak is truncated, and is said to have fallen in during an eruption in 1786. From Alaska the line is con- tinued through the Aleutian or Fox Islands to Kamtschatka. Inthe Aleutian Archipelago eruptions are frequent, and about thirty miles to the north of Unalaska, near the Isle of Um- nack, a new island was formed in 1796. It was first observed after a storm, at a point in the sea from which a column of smoke had been seen to rise. Flames then issued from the * See map of Smite ones in Von Coral Reefs, &c. London, 1842. In the Buch’s work on the Can annexed map, fig. 59, I have copied t Von Buch, ibid. 409. with permission a small part of the valu- { Darwin, Structure and Distrib. of able map accompanying this work. 588 GEOGRAPHICAL BOUNDARIES (Cx. XXIII. new islet which illuminated the country for ten miles round ; a frightful earthquake shook the new-formed cone, and showers of stones were thrown as far as Umnack. The erup- tion continued for several months, and eight years afterwards, in 1804, when it was explored by some hunters, the soil was so hot in some places that they could not walk on it. Accord- ing to Langsdorf and others, this new island, which is now several thousand feet high and two or three miles in circum- ference, has been continually found to have increased in size when successively visited by different travellers ; but we have no accurate means of determining how much of its growth, if any, has been due to upheaval, or how far it has been exclusively formed by the ejection of ashes and streams of lava. It seems, however, to be well attested that earthquakes of the most terrific description agitate and alter the bed of the sea and surface of the land throughout this tract. The line is continued in the southern extremity of the Peninsula of Kamtschatka, where, according to Dittmar, there are twelve active and twenty-six extinct volcanic cones. The largest and most active of these is Klutschew, lat. 56° 3’ N., which rises at once from the sea to the prodigious height of 15,000 feet. Within 700 feet of the summit, Erman saw, in 1829, a current of lava, emitting a vivid light, flow down the north-west side to the foot of the cone. Large quantities of ice and snow opposed for a time a barrier to the lava, until at length the fiery torrent overcame, by its heat and pressure, this obstacle, and poured down the mountain side with a frightful noise, which was heard for a distance of more than fifty miles.* Mont Blanc is 15,760 feet high, but a flow of lava from its summit to the base in the valley of Chamouni would give a very inadequate idea of the descent of the Kamtschatka cur- rent, because Chamouni is 3,500 feet above the level of the sea.t The Kurile chain of islands constitutes the prolongation of the Kamtschatka range, where a train of voleanic mountains, nine of which are known to have been in eruption, trends in a * Von Buch, Descrip. des Iles Canar. Kamtschatka, and Kurile region, see p. 450, who cites Erman and others. Alexis Perry, Soc. Imp. de Lyon, 1863. t For later eruptions in the Alaska, ee es NO ee a (a. XXUI.] OF VOLCANIC REGIONS. 589 southerly direction. The line is then continued to the south- west in the great island of Jesso, and again in Nipon, the principal of the Japanese group. It then extends by Loo Choo and Formosa to the Philippine Islands, and thence by Sangir and the north-eastern extremity of Celebes to the Moluccas (see map, fig. 59). Afterwards it passes westward through Sumbawa to Java. There are said to be thirty-eight considerable volcanos in Java, some of which are more than 10,000 feet high. They are remarkable for the quantity of sulphur and sulphureous yapours which they discharge. They rarely emit lava, but rivers of mud issue from them, like the moya of the Andes of Quito. The memorable eruption of Galongoon, in 1822, will be described in the twenty-sixth chapter. The crater of Taschem, at the eastern extremity of Java, contains a lake strongly impregnated with sulphuric acid, a quarter of a mile long, from which a river of acid water issues, which supports no living creature, nor can fish live in the sea near its confluence. There is an extinct crater near Batur, called Guevo Upas, or the Valley of Poison, about half a mile in circumference, which is justly an object of terror to the inhabitants of the country. Every living being which penetrates into this valley falls down dead, and the soil is covered with the carcasses of tigers, deer, birds, and even the bones of men; all killed by the abundant emanations of carbonic acid gas, by which the bottom of the valley is filled. In another crater in this land of wonders, near the volcano of Talaga Bodas, we learn from Mr. Reinwardt, that the sulphureous exhalations have killed tigers, birds, and innu- merable insects ; and the soft parts of these animals, such as fibres, muscles, nails, hair, and skin, are very well preserved, While the bones are corroded, and entirely destroyed. We learn from observations made in 1844, by Mr. Jukes, that a recent tertiary formation composed of limestone and resembling the coral rock of a fringing reef, clings to the flanks of all the volcanic islands from the east end of Timor to the west end of Java. These modern calcareous strata are often white and chalk-like, sometimes 1,000 feet and up- wards above the sea, regularly stratified in thick horizontal 590 GEOGRAPHICAL BOUNDARIES [Cu. XXIII. beds, and they show that there has been a general elevation of these islands at a comparatively modern period.* The same linear arrangement which is observed in Java holds good in the volcanos of Sumatra, some of which are of great height, as Berapi, which is more than 12,000 feet above the sea, and is continually smoking. Hot springs are abun- dant at its base. The volcanic line then inclines slightly to the north-west, and points to Barren Island, lat. 12° 15’ N., in the Bay of Bengal; a volcano often observed to emit smoke and vapours, and from which lava has proceeded since 1790 (see below, Chap. XXVII.). The volcanic train then extends, according to Dr. Macclelland, to the island of Nar- condam, lat. 13° 22’ N., which is a cone seven or eight hun- dred feet high, rising from deep water, and said to present signs of lava currents descending from the crater to the base. Afterwards the train stretches in the same direction to the volcanic island of Ramree, about lat. 19° N., and the adjoin- ing island of Cheduba, which is represented in old charts as a burning mountain. Thus we arrive at the Chittagong coast, which in 1762 was convulsed by a tremendous earthquake (see Chap. XXX.).+ To enumerate all the volcanic regions of the Indian and Pacific oceans would lead me far beyond the proper limits of this treatise; but it will appear in the last chapter of this work, when coral reefs are treated of, that the islands of the Pacific consist alternately of linear groups of two classes, the one lofty, and containing active volcanos, and marine strata above the sea-level, and which have been undergoing upheaval in modern times; the other very low, consisting of reefs of coral, usually with lagoons in their centres, and in which there is evidence of a gradual subsidence of the eround. The extent and direction of these parallel volcanic bands has been depicted with great. care by Darwin in his map before cited (p. 387). The most remarkable theatre of volcanic activity in the Northern Pacific—or, perhaps, in the whole world—occurs * Paper read at ects o Brit. + Macclelland, Report on Coal and Assoc. Southampton, Sept. 1 Min. Resources of India. Calcutta, 1888. od 38. Ci. XXIII] OF VOLCANIC REGIONS. 591 in the Sandwich Islands, which have been tal ably treated of ina work published by Mr. Dana in 1849 Volcanic region from Central Asia to the Capes —Another great region of subterranean disturbance is that which has been boagined to extend through a large part of Central Asia to the Azores, that is to say, from China and Tartary through Lake Aral and the Caspian to the Caucasus and the countries pordering the Black Sea, then again through part of Asia Minor to Syria, and westward to the Grecian Islands, Greece, Naples, Sicily, the southern part of Spain, Portugal, and the Azores. The breaks in this supposed continuous series of yoleanic disturbances are of such extent that the connection as a linear group cannot be insisted on, but it may be useful in helping us to remember the geographical limits within which certain volcanos and earthquakes of historical date have been witnessed. Respecting the eastern extremity of this line in China, we have little information, but many violent earthquakes are known to have occurred there. The yoleano said to have been in eruption in the seventh century in Central Tartary is situated on the northern declivity of the Celestial Mountains, not far distant from the large lake called Issikoul; and Humboldt mentions other vents and solfataras in the same quarter, which are all worthy of notice, as being far more distant from the ocean (260 geographical miles) than any other known points of eruption. We find on the western shores of the Caspian, in the country round Baku, a tract called the Field of Fire, which continually emits inflammable gas, while springs of naphtha and petroleum occur in the same vicinity, as also mud voleanos. Syria and Palestine abound in volcanic appear- ances, and very extensive areas have been shaken, at different periods, with great destruction of cities and loss of lives. Continual mention is made in history of the ravages com- mitted by earthquakes in Sidon, Tyre, Berytus, Laodicea, and Antioch, and in the Island of Cyprus. The country around the Dead Sea exhibits in some spots layers of sulphur and oo forming a superficial deposit, supposed by Mr. ology of the American Exploring a See also Lyell’s Elements of ease ‘Sandwich I. Voleanos ’—Index 592 GEOGRAPHICAL BOUNDARIES (Cu. XXIII. Tristram to be of volcanic origin. A district near Smyrna, in Asia Minor, was termed by the Greeks Catacecaumene, or ‘the burnt up,’ where there is a large arid territory, without trees, and with a cindery soil.* This country was visited in 1841 by Mr. W. J. Hamilton, who found in the valley of the Hermus perfect cones of scorize, with lava-streams, like those of Auvergne, conforming to the existing river-channels, and with their surface undecomposed.t Grecian Archipelago.—Proceeding westwards, we reach the Grecian Archipelago, where Santorin, afterwards to be de- scribed, is the grand centre of volcanic action. It was Von Buch’s opinion that the volcanos of Greece were arranged in a line running N.N.W. and 8.8.E., and that they afforded the only example in Europe of active volcanos having a linear direction; but M. Virlet, on the contrary, announces as the result of his investigations, made during the French expedition to the Morea in 1829, that there is one determinate line of direction for the volcanic phenomena in Greece, whether we follow the points of erup- tions, or the earthquakes, or any other signs of igneous agency. Macedonia, Thrace, and Epirus have always been subject to earthquakes, and the Ionian Isles are continually con- vulsed. Respecting Southern Italy, Sicily, and the Lipari Isles, it is unnecessary to enlarge here, as I shall have occasion again to allude to them. I may mention, however, that a band of volcanic action has been traced by Dr. Daubeny across the Italian Peninsula, from Ischia to Mount Vultur, in Apulia, the commencement of the line being found in the hot springs of Ischia, after which it is prolonged through Vesuvius to the Lago d’Ansanto, where gases similar to those of Vesuvius are evolved. Its farther extension strikes Mount Vultur, a lofty cone composed of tuff and lava, from one side of which carbonic acid and sulphuretted hydrogen are emitted.§ * Strabo, ed. Fal. p. § France, tom. iil. p. 109. : ae searches in a tae vol. il. § Daubeny on a Vols Ash- m oes Memoirs. Oxford, 1835 ne irlet, Bulletin de la Soe. Géol. de \ she Cu. XXIII] OF VOLCANIC REGIONS. Traditions of deluges.—-The traditions which have come down to us from remote ages of great inundations said to have happened in Greece and on the confines of the Grecian settlements, had doubtless their origin in a series of local catastrophes, caused principally by earthquakes. The fre- quent migrations of the earlier inhabitants, and the total want of written annals long after the first settlement of each country, make it impossible for us at this distance of time to fix either the true localities or probable dates of these events. The first philosophical writers of Greece were, therefore, as much ata loss as ourselves to offer a reasonable conjecture on these points, or to decide how many catastrophes might sometimes have become confounded in one tale, or how much this tale may have beenamplified, in after times, or obscured by mythological fiction. The floods of Ogyges and Deuca- lion are commonly said to have happened before the Trojan war; that of Ogyges more than seventeen, and that of Deu- calion more than fifteen, centuries before our era. As to the Ogygian flood, it is generally described as having laid waste Attica, and was referred by some writers to a great overflow- ing of rivers, to which cause Aristotle also attributed the deluge of Deucalion, which, he says, affected Hellas only, or the central part of Thessaly. Others imagined the same event to have been due to an earthquake, which threw down masses of rock, and stopped up the course of the Peneus in the narrow defile between mounts Ossa and Olympus. As to the deluge of Samothrace, which is generally re- ferred to a distinct date, it appears that the shores of that small island and the adjoining mainland of Asia were inun- dated by the sea. Diodorus Siculus says that the inhabi- tants had time to take refuge in the mountains, and save themselves by flight ; he also relates, that long after the event ¢ fishermen of the island drew up in their nets the capitals of columns,‘ which were the remains of cities submerged by that terrible catastrophe.’* These statements scarcely leave any doubt that there occurred, at the period alluded to, a subsidence of the coast, accompanied by earthquakes * Book vy. ¢ - ch. xlvii—See Letter of M. Virlet, Bulletin de la Soc. Géol. de France, tom. ii. 341. QQ 594 GEOGRAPHICAL BOUNDARIES (Cu. XXII. and inroads of the sea. ‘It is not impossible that the story of the bursting of the Black Sea through the Thracian Bos- phorus in the Grecian Archipelago, which accompanied, and, as some say, caused the Samothracian deluge, may have reference to a wave or succession of waves, raised in the Euxine by the same convulsion. We know that subterranean movements and volcanic erup- tons are often attended not only by incursions of the sea, but also by violent rains, and the complete derangement of the river drainage of the inland country, and by the damming up of the outlets. of lakes by landslips, or obstructions in the courses of subterranean rivers, such as abound in Thessaly and the Morea. We need not therefore be surprised at the variety of causes assigned for the traditional floods of Greece, by Herodotus, Aristotle, Diodorus, Strabo, and others. As to the area embraced, had all the Grecian deluges occurred simultaneously, instead of being spread over many centuries, and had they, instead of being extremely local, reached at once from the Euxine to the south-western limit of the Pelopon- nese, and from Macedonia to Rhodes, the devastation would still have been more limited than that already alluded to p- 580, which visited Chili in 1835, when a volcanic eruption broke out in the Andes, opposite Chiloe, and another at Juan Fernandez, distant 720 geographical miles, at the same time that several lofty cones, in the Cordillera, 400 miles to the eastward of that island, threw out vapour and ignited matter. Throughout a great part of the space thus recently shaken in South America, cities were laid in ruins, or the land was permanently upheaved, or mountainous waves rolled in- land from the Pacific. Periodical alternation of earthquakes in Syria and Southern Ttaly.—It has been remarked by Von Hoff, that from the commencement of the thirteenth to the latter half of the seventeenth century, there was an almost entire cessation of earthquakes in Syria and Judea; and, during this interval of quiescence, the Archipelago, together with part of the ad- jacent coast of Lesser Asia, as also Southern Italy and Sicily, suffered greatly from earthquakes ; while volcanic eruptions were unusually frequent in the same regions. A more ex- Cu, XXIIT.] OF VOLCANIC REGIONS, D95 tended comparison, also, of thé history of the subterranean convulsions of these tracts seems to confirm the opinion, that a violent crisis of commotion never visits both at the same time. It is impossible for us to declare, as yet, whether this phenomenon is constant in this and other regions, because we can rarely trace back a connected series of events farther than a few centuries; but it is well known that, where numerous vents are clustered together within a small area, as in many archipelagos for instance, two of them are never in violent eruption at once. If the action of one becomes very great for a century or more, the others assume the ap- pearance of spent volcanos. It is, therefore, not improbable that separate provinces of the same great range of volcanic fires may hold a relation to one deep-seated focus, analogous to that which the apertures of a small group bear to some more superficial rent or cavity. Thus, for example, we may conjecture that, at a comparatively small distance from the surface, Ischia and Vesuvius mutually communicate with certain fissures, and that each affords relief alternately to elastic fluids and lava there generated. So we may suppose Southern Italy and Syria to be connected, at a much ereater depth, with a lower part of the very same system of fissures ; in which case any obstruction occurring in one duct may have the effect of causing almost all the vapour and melted matter to be forced up the other, and if they cannot get vent, they may be the cause of violent earthquakes. Some objec- tions advanced against this doctrine that ‘volcanos act as safety-valves,’ will be considered in the sequel.* The north-eastern portion of Africa, including Egypt, which lies six or seven degrees south of the volcanic line already traced, has been almost always exempt from earth- (wakes ; but the north-western portion, especially Fez and Morocco, which fall within the line, suffer greatly from time to time. The southern part of Spain also, and Portugal, have senerally been exposed to the same scourge simultaneously mith Northern Africa. The provinces of Malaga, Murcia, ind Granada, and in Portugal the country round Lisbon, w@ recorded at several periods to have been devastated by * See Ch. XXXIL, Cause of Volcanic Eruptions. @aQ 2 596 AROGRAPHICAT BOUNDARIES 'Cu. OX lee great earthquakes. It will be seen, from Michell’s account of the great Lisbon shock in 1755, that the first movement proceeded from the bed of the ocean ten or fifteen leagues from the coast. So late as February 2, 1816, when Lisbon was vehemently shaken, two ships felt a shock in the ocean west from Lisbon; one of them at the distance of 120, and the other 262 French leagues from the coast *—a, fact which is more interesting, because a line drawn through the Grecian Archipelago, the volcanic region of Southern Italy, Sicily, Southern Spain, and Portugal, will, if prolonged west- ward through the ocean, strike the volcanic group of the Azores, which may possibly therefore have a submarine con- nection with the Huropean line. In regard to the volcanic system of Southern Europe, it may be observed, that there is a central tract where the greatest earthquakes prevail, in which rocks are shattered, mountains rent, the surface elevated or depressed, and cities laid in ruins. On each side of this line of greatest commo- tion there are parallel bands of country where the shocks are less violent. Ata still greater distance (as in Northern Italy, for example, extending to the foot of the Alps), there are spaces where the shocks are much rarer and more feeble, yet possibly of sufficient force to cause, by continued repetition, some appreciable alteration in the external form of the earth’s crust. Beyond these limits, again, all countries are liable to slight tremors, at distant intervals of time, when some great crisis of subterranean movement agitates an adjoining vol- canic region; but these may be considered as mere vibrations, propagated mechanically through the external covering of the globe, as sounds travel almost to indefinite distances through the air. Shocks of this kind have been felt in Eng- land, Scotland, Northern France, and Germany particularly during the Lisbon earthquake. But these countries cannot, on this account, be supposed to constitute parts of the south- ern voleanic region, any more than the Shetland and Orkney Tslands can be considered as belonging to the Tcelandic cirele, because the sands ejected from Hecla have been wafted thither by the winds. * Verneur, Journal des Voyages, tom, iy. p. 111.-—Von Hoff, vol. li. p. 279. i=] —# ia Cx, XXII] OF VOLCANIC REGIONS. 597 Besides the continuous spaces of subterranean disturbance, of which we have merely sketched the outline, there are other disconnected voleanic groups of which several will be men- tioned here after. Lines of active and extinct volcanos not to be confounded.— We must always be careful to distinguish between lines of extinct and active volcanos, even where they appear to run in the same direction ; for ancient and modern systems may in- terfere with each other. Already, indeed, we have proof that this is the case; so that it is not by geographical position, but by reference to the species of organic beings alone, whether aquatic or terrestrial, whose remains occur in beds interstratified with lavas, that we can clearly distinguish the relative age of v oleanos of which no eruptions are recorded. Had Southern Italy been known to civilised nations for as short a period as America, we should have had no record of eruptions in Ischia; yet we might have assured ourselves that the lavas of that isle had howe since the Mediterranean was inhabited by the species of testacea now living in the Neapolitan seas. With this assurance, it would not have been rash to include the numerous vents of that island in the modern volcanic group of Campania. On similar grounds we may infer, without much hesitation, that the eruptions of Etna, and the modern earthquakes of Calabria, are a continuation of that action which, at a some- what earlier period, produced the submarine lavas of the Val di Noto in Sicily. But, on the other hand, the lavas of the Euganean Hills and the Vicentin, although not wholly beyond the range of earthquakes in Northern Italy, must not be confounded with any existing volcanic system; for when they flowed, the seas were inhabited by animals of the Eocene period, almost all of them distinct from those now known to ae whether in the Mediterranean or other parts of the globe. CHAPTER XXIV. VOLCANIC DISTRICT OF NAPLES. HISTORY OF THE VOLCANIC ERUPTIONS IN THE DISTRICT ROUND NAPLES— ARLY CONVULSIONS IN THE ISLAND OF ISCHIA —NUMEROUS CONES THROWN UP THERE—LAKE AVERNUS—THE SOLFATARA—RENEWAL OF THE ERUPTIONS OF VESUVIUS, A.D. 79.—PLINY’S DESCRIPTION OF THE PHENOMENA—HIS SILENCE RESPECTING THE DESTRUCTION OF HERCULANEUM AND POMPEII— SUBSEQUENT HISTORY OF VESUVIUS—LAVA DISCHARGED IN ISCHIA IN 1302 —PAUSE IN THE ERUPTIONS OF VESUVIUS—MONTE NUOVO THROWN UP— UNIFORMITY OF THE VOLCANIC OPERATIONS OF YVESUVIUS AND PHLEGRZAN FIELDS IN ANCIENT AND MODERN TIMES. I sHALL next give a sketch of the history of some of the vol- canic vents dispersed throughout the great regions before described, and consider the composition and arrangement of their lavas and ejected matter. The only volcanic region known to the ancients was that of the Mediterranean; and even of this they have transmitted to us very imperfect records relating to the eruptions of the three principal dis- tricts, namely, that round Naples, that of Sicily and its isles, and that of the Grecian Archipelago. By far the most con- nected series of records throughout a long period relates to the first of these provinces; and these cannot be too atten- tively considered, as much historical information is indis- pensable in order to enable us to obtain a clear view of the connection and alternate mode of action of the different vents in a single volcanic group. Karly convulsions in the Island of Ischia.—The Neapolitan volcanos extend from Vesuvius, through the Phlegrean Fields, to Procida and Ischia, in a somewhat linear arrangement, ranging from the north-east to the south-west, as will be seen in the annexed map of the volcanic district of Naples ¥ q Gu, XXIV.) VOLCANIC ERUPTIONS OF ISCHIA. 599 (fig. 60). Within the space above limited, the volcanic force ig sometimes developed in single eruptions from a consider- able number of irregularly scattered points; but a great part of its action has been confined to one principal and habitual vent, Vesuvius or Somma. Before the Christian era, from the remotest periods of which we have any tradition, this a Nola Mee o1mma <-Oltaianv . Torre delGree® Ss Capo di Miseno Torrede er Aschia (i PROCIDA Torre de o4 Annunzih® 2 7s ont i Castell a Mare \y, oY (7) avs << | Capo di Sorren lo VOLCANIC DISTRICT | OF NAPLES. A. Astroni. B. Monte Barbaro. M. Monte Nuovo. S. The Solfatara. principal vent was in a state of inactivity. But terrific convulsions then took place from time to time in Ischia (Pithecusa), and seem to have extended to the neighbouring isle of Procida (Prochyta) ; for Strabo* mentions a story of Procida having been torn asunder from Ischia ; and Plinyt derives its name from its having been poured forth by an eruption from Ischia. . The present circumference of Ischia along the water’s edge is eighteen miles, its length from west to east about five, and. its breadth from north to south three miles. Several Greek colonies which settled there before the Christian era were compelled to abandon it in consequence of the violence of the * Tab. v. + Nat. Hist. lib. iii. ¢. 6. 600 VOLCANIC ERUPTIONS OF ISCHIA. fen Xk xTy? eruptions. First the Erythreans, and afterwards the Chal- cidians, are mentioned as having been driven out by earth- quakes and igneous exhalations. A colony was afterwards established by Hiero, king of: Syracuse, about 380 years before the Christian era; but when they had built a fortress, they were compelled by an eruption to fly, and never again returned. Strabo tells us that Timeeus recorded a tradition, that, a little before his time, Epomeus, the principal moun- tain in the centre of the island, vomited fire during great earthquakes; that the land between it and the coast had ejected much fiery matter, which flowed into the sea, and that the sea receded for the distance of three stadia, and then returning, overflowed the island. This eruption is supposed by some to have been that which formed the crater of Monte Corvo on one of the higher flanks of Epomeo, above Foria, the lava-current of which may still be traced, by aid of the scorize on its surface, from the crater to the sea. To one of the subsequent eruptions in the lower parts of the isle, which caused the expulsion of the first Greek colony, Monte Rotaro has been attributed, and it bears every mark of recent origin. The cone, which I examined in 1828, is oD eay tien and has a crater on its summit pre- cisely bling that of Monte Nuovo near Naples ; but the hill is larger, a resembles some of the more considerable cones of single eruption near Clermont in Auvergne, and, like some of them, it has given vent to a lavaceeeea at its base, instead of its summit. A small ravine swept out by a torrent exposes the structure of the cone, which is composed of innumerable inclined and slightly undulating layers of pumice, scorize, white lapilli, and enormous angular blocks of trachyte. These last have evidently been thrown out by violent explosions, like those which in 1822 launched from Vesuvius a mass of augitic lava, of many tons’ weight, to the distance of three miles, which fell in the garden of Prince Ottajano. The cone of Rotaro is covered with the arbutus, and other beautiful evergreens. Such is the strength of the virgin soil, that the shrubs have become almost arborescent ; and the growth of some of the smaller wild eT ee 7 — Cu. XXIV. ] VOLCANIC ERUPTIONS OF ISCHIA. 601 plants has been so vigorous, that botanists have scarcely been able to recognise the species. The eruption which dislodged the Syracusan colony is sup- posed to have given rise to that mighty current which forms Fig. 61 SS SS — mae at SEE Part of Ischia seen from the West. From a drawing by G. P. Scrope. a. Monte Epomeo. b. Monte Vico. c. Another of the minor cones with a crater.* the promontory of Zaro and Caruso. The surface of these lavas is still very arid and bristling, and is covered with black scoriz; so that it is not without great labour that human industry has redeemed some small spots, and con- verted them into vineyards. Upon the produce of these vineyards the population of the island is almost entirely supported. It amounted when I was first there, in 1828, to about twenty-five thousand, and was on the increase. From the date of the great eruption last alluded to, down to our own time, Ischia has enjoyed tranquillity, with the exception of one emission of lava hereafter to be described, which, although it occasioned much local damage, does not appear to have devastated the whole country, in the manner of more ancient explosions. There are, upon the whole, on different parts of Epomeo, or scattered through the lower tracts of Ischia, twelve considerable volcanic cones which have been thrown up since the island was raised above the surface of the deep; and many streams of lava may have flowed, like that of ‘Arso’ in 1302, without cones having been produced ; so that this island may, for ages before the period of the remotest traditions, have served as a safety- * See G. Poulett Scrope, Geol. Trans. 2d series, vol. ii. pl. 34. 602 LAKE AVERNUS.—VESUVIUS. [Cu. XXIV. valve to the whole Terra di Lavoro, while the fires of Vesu- vius were dormant. Lake Avernus.—It seems also clear that Avernus, a cine lake near Puzzuoli, about half a mile in diameter, which is now a salubrious and cheerful spot, once exhaled mephitic vapours, such as are often emitted by craters after eruptions. There is no reason for discrediting the account of Lucretius, that birds could not fly over it without being stifled, although they may now frequent it uninjured.* There must have been a time when this crater was in action; and for many cen- turies afterwards it may have deserved the appellation of ‘atri jauna Ditis,’ emitting, perhaps, gases as destructive of animal life as those suffocating vapours given out by Lake Quilotoa, in Quito, in 1797, by which whole herds of cattle on its shores were killed,+ or as those deleterious emanations which annihilated all the cattle in the island of Lancerote, one of the Canaries, in 1730.t Bory St. Vincent mentions, that in the same isle birds fell lifeless to the ground ; and Sir | William Hamilton informs us that he pee up dead birds on Vesuvius during an eruption. Solfatara.—The Solfatara, near Puzzuoli, which may be considered as a nearly extinguished crater, appears, by the accounts of Strabo and others, to have been before the Chris- tian era in very much the same state as at present, giving vent continually to aqueous vapour, together with sulphu- reous and muriatic acid gases, like those evolved by Vesuvius. Ancient history of Vesuvius.—Such, then, were the points where the subterranean fires obtained vent, from the earliest period to which tradition reaches back, down to the first cen- tury of the Christian era ; but we then arrive at a crisis in the volcanic action of this district—one of the most interesting events witnessed by man during the brief period throughout which he has observed the physical changes on the earth’s surface. From the first colonisation of Southern Italy by the Greeks, Vesuvius afforded no other indications of its voleanic De Rerum Nat. vi. 740.—Forbes, + Von Buch, Ueber einen vulean- on Bay of phatgaa Edin. Journ. of Sei., | ischen Ausbruch auf der Insel Lanze- No. ili. new serie , p. 87. Jan. 1830. rote, + Humboldt, “aS Deel 7 Cu. XXIV.| ERUPTION OF VESUVIUS, A.D. 79. 603 character than such as the naturalist might infer, from the analogy of its structure to other volcanos. These were recog- nised by Strabo, but Pliny did not include the mountain in his list of active vents. The ancient cone was of a very regular form, terminating not as at present, in two peaks, but with a summit which presented, when seen from a dis- tance, the even outline of an abruptly truncated cone. On the summit, as we learn from Plutarch, there was a crater with steep cliffs, and having its interior overgrown with wild vines, and with a sterile plain at the bottom. On the ex- terior, the flanks of the mountains were clothed with fertile fields richly cultivated, and at its base were the populous cities of Herculaneum and Pompeii. But the scene of repose was at length doomed to cease, and the volcanic fire was re- called to the main channel, which at some former unknown period had given passage to repeated streams of melted lava, sand, and scorie. Renewal of its erwptions.—The first symptom of the revival of the energies of this volcano was the occurrence of an earthquake in the year 63 after Christ, which did considerable injury to the cities in its vicinity. From that time to the year 79 slight shocks were frequent; and in the month of Aueust of that year they became more numerous and violent, till they ended at length in an eruption. The elder Pliny, who commanded the Roman fleet, was then stationed at Misenum; and in his anxiety to obtain a near view of the phenomena, he lost his life, being suffocated by sulphureous vapours. His nephew, the younger Pliny, remained at Misenum, and has given us, in his Letters, a lively descrip- tion of the awful scene. A dense column of vapour was first seen rising vertically from Vesuvius, and then spreading it- self out laterally, so that its upper portion resembled the head, and its lower the trunk of the pine, which characterises the Italian landscape. This black cloud was pierced occa- sionally by flashes of fire as vivid as lightning, succeeded by darkness more profound than night. Ashes fell even upon the ships at Misenum, and caused a shoal in one part of the sea—the ground rocked, and the sea receded from the shores, so that many marine animals were seen on the dry sand. 604 ERUPTION OF VESUVIUS, A.D. 79. (Cu. XXIV. The appearances above described agree perfectly with those witnessed in more recent eruptions, especially those of Monte Nuovo in 1538, and of Vesuvius in 1822. The younger Pliny, although giving a circumstantial detail of so many physical facts, and describing the eruption and earthquake, and the shower of ashes which fell at Stabie, makes no allusion to the sudden overwhelming of two large and populous cities, Herculaneum and Pompeii. In explana- tion of this omission, it has been suggested that his chief object was simply to give Tacitus a full account of the par- ticulars of his uncle’s death. It is worthy, however, of re- mark, that had the buried cities never been discovered, the accounts transmitted to us of their tragical end might well have been discredited by the majority, so vague and general are the narratives, or so long subsequent to the event. Taci- tus, the friend and contemporary of Pliny, when adverting in general terms to the convulsions, says merely that ‘cities were consumed or buried.’ * Suetonius, although he alludes to the eruption inciden- tally, is silent as to the cities. They are mentioned by Martial, in an epigram, as immersed in cinders ; but the first historian who alludes to them by name is Dion Cassius, + who flourished about a century and a half after Pliny. He appears to have derived his information from the traditions of the inhabitants, and to have recorded, without discrimina- tion, all the facts and fables which he could collect. He tells us, ‘that during the eruption a multitude of men of super- human stature, resembling giants, appeared, sometimes on the mountain, and sometimes in the environs—that stones and smoke were thrown out, the sun was hidden, and then the giants seemed to rise again, while the sounds of trumpets were heard, &c. &c.; and finally,’ he relates, ‘two entire cities, Herculaneum and Pompeii, were buried under showers of ashes, while all the people were sitting in the theatre.’ That many of these circumstances were invented, would have been obvious, even without the aid of Pliny’s letters; and the examination of Herculaneum and Pompeii enables us to * ‘Hauste aut obrute urbes’—Hist. lib. i. f Hist. Rom. lib. Ixvi. Real 1 Cu. XXIV.) ERUPTION IN ISCHIA, A.D. 1302. 605 prove, that none of the people were destroyed in the theatres, and indeed, that there were very few of the inhabitants who did not escape from both cities. Yet some lives were lost, and there was ample foundation for the tale in its most es- gential particulars. It does not appear that in the year 79 any lava flowed from Vesuvius ; the ejected substances, perhaps, consisted entirely of lapilli, sand, and fragments of older lava, as when Monte Nuovo was thrown up in 1538. The first era at which we have authentic accounts of the flowing of a stream of lava, is the year 1036, which is the seventh eruption from the revi- val of the fires of the volcano. A. few years afterwards, in 1049, another eruption is mentioned, and another in 1138 (or 11389), after which a great pause ensued of 168 years. During this long interval of repose, two minor vents opened at distant points. First, it is on tradition that an eruption took place from the Solfatara in the year 1198, during the reign of Frederick II., Emperor of Germany ; and although no circumstantial detail of the event has reached us from those dark ages, we may receive the fact without. hesitation.* Nothing more, however, can be attributed to this eruption, as Mr. Scrope observes, than the discharge of a light and scoriform trachytic lava (that of Monte Olivano), of recent aspect, resting upon the strata of loose tuff which covers the principal mass of trachyte.t Volcanic eruption in Ischia, 1302.—The other occurrence is well authenticated,—the eruption, in the year 1302, of a lava-stream from a new vent on the south-east end of the Island of Ischia. During part of 1301, earthquakes had succeeded one another with fearful rapidity; and they ter- minated at last with the discharge of a lava-stream from a point named the Campo del Arso, not far from the town of Ischia. This lava ran quite down to the sea—a distance of about two miles: in colour it varies from iron grey to red- dish black, and is remarkable for the glassy felspar which it * The earliest authority, says Mr. &c. No.i. new series, p. 127. July 1829 be Capaccio, quoted in the Terra Tre- + Geol. Trans., second series, vol. ii. mante of Bonito.—Edin. Journ. of Sci. pp. 346. 606 HISTORY OF VESUVIUS AFTER 1138. [Cu. XXIV. contains. Its surface is almost as sterile, after a period of five centuries, as if it had cooled down yesterday. A few scantlings of wild thyme, and two or three other dwarfish plants, alone appear in the interstices of the scorix, while the Vesuvian lava of 1767 is already covered with a luxuriant vegetation. Pontanus, whose country-house was burnt and overwhelmed, describes the dreadful scene as having lasted two months.* Many houses were swallowed up, and a par- tial emigration of the inhabitants followed. This eruption produced no cone, but only a slight depression, hardly de- serving the name of a crater, where heaps of black and red scorie lie scattered around. Until this eruption, Ischia is generally believed to have enjoyed an interval of rest for about seventeen centuries ; but Julius Obsequens,+ who flou- rished A.D. 214, refers to some volcanic convulsions in the year 662 after the building of Rome (91 B.c.). As Pliny, who lived a century before Obsequens, does not enumerate this among other volcanic eruptions, the story has been thought erroneous, and it may perhaps relate to some sub- terranean commotions of no great violence. History of Vesuvius after 1138.—To return to Vesuvius :— the next eruption occurred in 1306; between which era and 1631 there was only one other (in 1500), and that a slight one. It has been remarked, that throughout this period Ktna was in a state of such unusual activity, as to lend coun- tenance to the idea that the great Sicilian voleano may sometimes serve as a channel of discharge to elastic fluids and lava that would otherwise rise to the vents in Campania. But we have not sufficient data as yet to enable us to form an opinion whether such a coincidence may not have been accidental and exceptional. Where voleanic vents are dis- tinctly arranged in a linear series, the subterranean connec- tion of different portions of the line may be speculated upon more freely. Formation of Monte Nuovo, 1538.—The great pause was also marked by a memorable event in the Phlegrean Fields —the sudden formation of a new mountain in 1538, of which * Lib. vi. de aon Nei bs in Greevil Thesaur. tT Prodig. libel. ¢. ex Cu. XXIV.] FORMATION OF MONTE NUOVO. 607 we have received authentic accounts from contemporary writers. The height of this mountain, ealled ever since Monte Nuovo, has been determined, by the Italian mineralogist Pini, to be 440 English feet above the level of the bay; its base is about 8,000 feet, or more than a mile and a half in circumference. According to Pini, the depth of the Fig. 62. Monte Nuovo, formed in the Bay of Baie, Sept. 29th, 1588. j 1. Cone of Monte Nuovo. 2. Brim of crater of ditto. 3. Thermal spring, called Baths of Nero, or Stufe di Tritoli. crater is 421 English feet from the summit of the hill, so that its bottom is only nineteen feet above the level of the sea. The cone is declared, by the best authorities, to stand partly on the site of the Lucrine Lake (4, fig. 63), which was nothing more than the crater of a pre-existent volcano, and was almost entirely filled during the explosion of 1538. Nothing now remains but a shallow pool, separated from the sea by an elevated beach, raised artificially. ' Sir William Hamilton has given us two original letters describing this eruption. The first, by Falconi, dated 1538, contains the following passages.* ‘ It is now two years since * Campi Phlegreei, p. 70. 608 ERUPTION OF SEPTEMBER, 1538. [Cu. XXIV. there have been frequent earthquakes at Puzzuoli, Naples, and the neighbouring parts. On the day and in the night before the eruption (of Monte Nuovo), above twenty shocks, ereat and small, were felt. The eruption began on the 29th of September, 1538. It was on a Sunday, about one o’clock in the night, when flames of fire were seen between the hot The Phlegreean Fields.* 4, Lucrine Lake. 2. Monte Barbaro. 5. The Solfatara. 2 38. Lake Avernus. 1. Monte Nuovo. 6. Puzzuoli. 7. Bay of Baie. baths and Tripergola. In a short time the fire increased to such a degree, that it burst open the earth in this place, and threw up so great a quantity of ashes and pumice-stones, mixed with water, as covered the whole country. The next morning (after the formation of Monte Nuovo) the poor in- habitants of Puzzuoli quitted their habitations in terror, covered with the muddy and black shower which continued the whole day in that country—flying from death, but with death painted in their countenances. Some with their children in their arms, some with sacks full of their goods; * These representations of the Phle- _Phlegreei,’ ; The faithfulness of his grean Fields, figs. 62, and 63, are re : - coloured delineations of the scenery of that* country cannot be too highly praised. duced from views given by Sir William Hamilton in his great work Campi Cu. XXIV. | ERUPTION OF MONTE NUOVO. 609 others leading an ass, loaded with their frightened family, towards Naples; others carrying quantities of birds, of various sorts, that had fallen dead at the beginning of the eruption ; others, again, with fish which they had found, and which were to be met with in plenty on the shore, the sea having left them dry for a considerable time. I accompanied Signor Moramaldo to behold the wonderful effects of the eruption. The sea had retired on the side of Baie, abandoning a con- siderable tract, and the shore appeared almost entirely dry, from the quantity of ashes and broken pumice-stones thrown up by the eruption. I saw two springs in the newly dis- covered ruins ; one before the house that was the Queen’s, of hot and salt water,’ &c. So far Falconi: the other account is by Pietro Giacomo di Toledo, which begins thus :—‘ It is now two years since this province of Campagna has been afflicted with earthquakes, the country about Puzzuoli much more so than any other parts: but on the 27th and the 28th of the month of September last, the earthquakes did not cease day or night in the town of Puzzuoli: that plain which lies between Lake Avernus, the Monte Barbaro, and the sea, was raised a little, and many cracks were made in it, from some of which issued water ; at the same time the sea, immediately adjoining the plain, dried up about two hundred paces, so that the fish were left on the sand a prey to the inhabitants of Puzzuoli. At last, on the 29th of the same month, about two o’clock in the night, the earth opened near the lake, and discovered a horrid mouth, from which were vomited furiously smoke, fire, stones, and mud, composed of ashes, making at the time of its opening a noise like the loudest thunder. The stones which followed were by the flames converted to pumice, and some of these were larger than an ow. 'The stones went about as high as a cross-bow can carry, and then fell down, sometimes on the edge, and sometimes into the mouth itself. The mud was of the colour of ashes, and at first very liquid, then by de- grees less so, and in such quantities, that in less than twelve hours, with the help of the above-mentioned stones, a moun- tain was raised of 1,000 paces in height. Not only Puzzuoli and the neighbouring country was full of this mud, but the VOL. I. RR 610 ERUPTION OF MONTE NUOVO. , [Cu. XXIV, city of Naples also; so that many of its palaces were defaced y it. Now this eruption lasted two nights and two days without intermission, though, it is true, not always with the same force; the third day the eruption ceased, and I went up with many people to the top of the new hill, and saw down into its mouth, which was a round cavity about a quarter of a mile in circumference, in the middle of which, the stones which had fallen were boiling up, just as a caldron of water boils on the fire. The fourth day it began to throw up again, and the seventh much more, but still with less violence than the first night. At this time many persons who were on the hill were knocked down by the stones and killed, or smothered with the smoke. In the day the smoke still continues, and you often see fire in the midst of it in the night-time.’ * Tt will be seen that both these accounts, written imme- diately after the birth of Monte Nuovo, agree in stating that the sea retired; and one mentions that its bottom was up- raised ; but they attribute the origin of the new hill exclu- sively to the jets of mud, showers of scoriz, and large frag- ments of rock, cast out from a central orifice, for several days and nights. Baron Von Buch, however, in his excellent work on the Canary Islands, and voleanic phenomena im general, has declared his opinion that the cone and crater of Monte Nuovo were formed, not in the manner above de- scribed, but by the upheaval of solid beds of white tuff, which were previously horizontal, but which were pushed up in 1538, so as to dip away in all directions from the centre, with the same inclination as the sloping surface of the cone itself. ‘It is an error,’ he says, ‘to imagine that this hill was formed by eruption, or by the ejection of pumice, scorie, and other incoherent matter; for the solid beds of upraised tuff are visible all round the crater, and it is merely the superficial covering of the cone which is made up of ejected scorle.’ F In confirmation of this view, M. Dufrénoy has cited a pas- sage from the works of Porzio, a celebrated physician of that * Campi Phlegrei, p. 77. + P. 347. Paris, 1836. r hte as autely al jamany. 4 mentio ‘woh, wh flads of ANptem Ube w forth Sepid, dy int] phe 80} rm Ca. XXIV. |] ERUPTION OF MONTE NUOVO. 611 period, to prove that in 1588 the ground where Monte Nuovo stands was pushed up in the form of a great bubble or blister, which on bursting gave origin to the present deep crater. Porzio says, ‘that after two days and nights of violent earthquakes, the sea retired for nearly 200 yards; so that the inhabitants could collect great numbers of fish on this part of the shore, and see some springs of fresh water which rose up there. At length, on the third day of the calends of October (September 29), they saw a large tract of ground intervening between the foot of Monte Barbaro and part of the sea, near the Lake Avernus, rise, and suddenly assume the form of an incipient hill; and at two o’clock at night, this heap of earth, opening as it were its mouth, vomited, with a loud noise, flames, pumice-stones, and ashes.”* So late as the year 1846 a fourth manuscript (written im- mediately after the eruption) was discovered and published inGermany. It was written in 1588 by Francesco del Nero, + who mentions the drying up of the bed of the sea near Puzzuoli, which enabled the inhabitants of the town to carry off loads of fish. About eight o’clock in the morning of the 29th September, the earth sunk down about fourteen feet in that place where the volcanic orifice now appears, and there issued forth a small stream of water, at first cold, and after- wards tepid. At noon, on the same day, the earth began to swell up in the same spot where it had sunk down fourteen feet, so as to form a hill. About this time fire issued forth, and gave rise to the great gulf, ‘ with such a force, noise, and shining light, that I, who was standing in my garden, was seized with terror. Forty minutes afterwards, although unwell, I got upon a neighbouring height, from which I saw all that took place, and by my troth it was a splendid fire, that threw up for a lone time much earth and many stones, which fell \ to) 2 agnus terre tractus, qui inter Omnis, Medica, Phil., et Mathemat., in 2160 Boat , quem Barbarum incole unum collecta, 1786, cited by Dufrénoy, appellant, et mare juxta Avernum jacet, Mém. pour servir a une Description Sese erigere videbatur, et montis subitd Géologique de la France, tom. iv. p. 274. hascentis figuram imitari. Eo ipso die + See Neues Jahr Buch for 1846, and horé noctis II., iste terre cumulus, a translation in the ais ras of aperto veluti ore, magno cum fremitu, the Geol. Soc. for 1847, vol, 1. p. 20. magnos | ignes evomuit ; Tye peesdae, et Memoirs lapides, cineresque. or zio, Opera BR 2 612 ERUPTION OF MONTE NUOVO. (Cu. XXIV. back again all round the gulf, in a semicircle of from one to three bow-shots in diameter, and, filling up part of the sea, formed a hill nearly of the height of Monte Morello. Masses of earth and stones, as large as an ox, were shot up from the fiery guif into the air, to a height which I estimate at a mile and a half. When they descended, some were dry, others in a soft muddy state.’ He concludes by alluding again to the sinking of the ground, and the elevation of it which fol- lowed, and says that to him it was inconceivable how such a mass of stones and ashes could have been poured forth from the gulf. He also refers to the account which Porzio was to draw up for the Viceroy. is On comparing these four accounts, recorded by eye-wit- nesses, there appears to be no real discrepancy between them. Itseems clear that the ground first sunk down fourteen feet on the site of the future volcano, and after having sub- sided it was again propelled upwards by the lava mingled with steam and gases, which were about to burst forth. Jets of red-hot lava, fragments of fractured rock, and ocea- sionally mud composed of a mixture of pumice, tuff, and sea-water, were hurled into the air. Some of the blocks of stone were very large, leading us to infer that the ground which sank and rose again was much shattered and torn to pieces by the elastic vapours. The whole hill was not formed at once, but by an intermitting action extending over a week or more. It seems that the chasm opened between Triper- gola and the baths in its suburbs, and that the ejected materials fell and buried that small town. A considerable part, however, of the hill was formed in less than twenty- four hours, and in the same manner as on a smaller scale the mud cones of air volcanos are produced, with a cavity in the middle. There is no difficulty in conceiving that the pumiceous mud, if so thrown out, may have set into a kind of stone on drying, just as some cements, composed of vol- canic ashes, are known to consolidate with facility. I am informed that Baron Von Buch discovered some marine shells of existing species, such as occur fossil in the tuff of the neighbourhood, in beds exposed low down in the walls of the crater of Monte Nuovo. These may have been here ila guned al at of tl a0 fewe dat IV) » WY) Siac aL were | cu, XXIV.] ERUPTION OF MONTE NUOVO. 613 ejected in the mud mixed with sea-water which was cast out of the boiling gulf; or, as Signor Arcangelo Scacchi has suggested, * they may have been derived from the older tuff, which contains marine shells of recent species. The same observer remarks that Porzio’s account upon the whole cor- yoborates the doctrine of the cone having being formed by eruption, in proof of which he cites the following passage :— ‘But what was truly astonishing, a hill of pumice-stones and ashes was heaped up round the gulf, to the height of a mile ina single night.+ Signor Scacchi also adds that the ancient temple of Apollo, now at the foot of Monte Nuovo, and the walls of which still retain their perfect perpendicula- rity, could not possibly have maintained that position had the cone of Monte Nuovo really been the result of upheaval. Tripergola was much frequented as a waterine-place, and contained an hospital for those who resorted there for the benefit of the thermal springs; and it appears that there were no fewer than three inns in the principal street. Had Porzio stated that any of these buildings, or the ruins of them, were seen by himself or others raised: up above the plain, a short time before the first eruption, so as to stand on the summit or slope of a newly-raised hillock, we might have been compelled, by so circumstantial a narrative, to adopt M. Dufrénoy’s interpretation. But in the absence of such evidence, we must appeal to the crater itself, where we behold a section of the whole mountain, without being able to detect any original nucleus of upheaved rock distinct from the rest: on the contrary, the whole mass is similar throughout in composition, and the cone very symmetrical in form; nor are there any clefts, such as might be looked for, as the effect of the sudden upthrow of stony masses. Mr. C. Prevost has well remarked that if beds of solid and non-elastic materials had yielded to a Violent pressure directed from below upwards, we should find hot simply a deep empty cavity, but an irregular opening, Where many rents converged; and these rents would be now Mem. Roy. Acad. Nap. 1849. ex pummicibus et cinere plusquam mille 7 ‘Verum quod omnem superat ad- passuum altitudine und nocte congestus Mirationem, mons circumeam yoraginem __aspicitur, 614 ERUPTION OF MONTE NUOVO. [Cu. XXIV. seen breaking through the walls of the crater, widening as they approach the centre. (See fig. 64, a, 5.)* Nota single ssure of this kind is observable in the interior of Monte Nuovo, where the walls of the crater are continu- ous and entire; nor are there any dikes implying that rents had ex- isted, which were afterwards filled with lava or other matter. It has moreover been often urged by Von Buch, De Beaumont, and others, who ascribe the conical form of voleanos chiefly to upheaval from below, that in such mountains there are a ereat number of deep rents and ravines, which diverge on all sides like the spokes of a wheel, from near the central axis to the circumference or base of the cone, as in the case of Palma, Cantal, and Teneriffe. Yet the entire absence of such divergent fissures or ravines, in such cases as Monte Nuovo, Somma, or Etna, is passed by unnoticed, and appears to have raised in their minds no Suet to their favourite theory. It is, indeed, admitted by M. Dufrénoy that there are some facts which it is very difficult to reconcile with his own view of Porzio’s record. Thus, for example, there are cer- tain Roman monuments at the base of Monte Nuovo, and on the borders of Lake Avernus, such as the temples of Apollo (before mentioned) and Pluto, which do not seem to have suffered in the least degree by the supposed upheaval. ‘The walls which still exist have preserved their vertical position, and the vaults are in the same state as other monuments on the shores of the Bay of Bais. The long gallery which led to the Sibyl’s Cave, on the other side of Lake Avernus, has in like manner escaped injury, the roof of the gallery re- maining perfectly horizontal, the only change being that the soil of the chamber in which the Sibyl gave out her oracles is now covered by a few inches of water, which merely indi- cates a slight alteration in the level of Lake Avernus.’+ On Fig. 64. * Mém. de la Soe. Géol. de France, tom 9 swe ay tN fY Dufrénoy, Mem. pour servir, &e. Dp. appears Lvourite re some lis OM wre Cel: Ge XXIV] ERUPTION OF MONTE NUOVO. 615 the enon then, that pre-existing beds of pumiceous iuff were upraise ad in 1558, so as to form Monte Nuovo, it ig acknow daod that the perfectly undisturbed state of the con- tiguous soil on which these ancient monuments stand, is very different from what might have been expected. Mr. Darwin, in his ‘ Voleanic Islands,’ has described several] erateriform hills in the Galapagos Archipelago as con 1posed of tuff which has evidently flowed like mud, and yet on con- solidating has preserved an inclination of twenty and even thirty degrees. The tuff does not fold in continuous sheet round the hills as would have happened if they had beer formed by the upheaval of horizontal layers. The ai describes the composition of the tuff as very similar + of Monte Nuovo, and the high angles at which t slope, both those which have flowed and those which have fallen in the form of ashes, entirely removes the separ! supposed by M. Dufrénoy to exist in regard to the slope of Monte Nuovo, where it exceeds an angle of 18° to 20°.* Mr. Dana, also, in his account of the Sandwich Is! ands,+ shows that in the ‘ cinder cones’ of that region, the strata have an original inclination of between 35° and 40°, while in the ‘tufa cones ® formed near the sea, the beds dda pe at about an angle of 30°. The same naturalist also observed in the Samoan or Navigator Islands in Polynesia, that fragments of fresh coral had been thrown up together with voleanic mat- ter to the height of 200 feet above the level of the sea in cones of tufa.t In October, 1857, I re-examined Monte Nuovo in company with Prof. A. Scacchi. On the south side of the mountain I saw both large and small blocks of trachyte entering into its composition, together with scorize, just as we might have ex- pected from the accounts handed down to us of the eruption. In the interior of the crater on the east and north-east sae an internal talus is seen, the beds of which slope at angles 26° and 30° degrees towards the centre or axis of the cone as at a, fig. 65. Such taluses are well known as characterisin g ~ a m O 1 ne Ftp * Darwin's Volcanic Islands, 106, Expedition, in 1838—1842, p- 354. note, t Ibid. p. 328 t Geology of the American Exploring 616 VOLCANOS OF THE PHLEGR@AN FIELDS. (Cu. XXIV. cones of eruption, being formed by those ejected materials which fall inside the margin of the wall of the crater, and which, although for the most part ejected again during sub- sequent explosions, often leave some monuments of their former existence. We found several fragments of marine shells Cardiwm, Cerithiwm, &c., as well as of Roman bricks, in these strata, and I myself picked up three pieces of Fig. 65. Section of Monte Nuovo showing the internal talus, a, a, on the inner slope of t ide. he crater on its north-east side pottery. Such remains are just what we might have looked for ; they are such as would have been showered down from above on a spot where the gaseous explosions burst through marine accumulations like those of the Starza, and by which the houses of Tripergola were blown into the air. I shall again revert to the doctrine of the origin of vol- canic cones by upheaval, when speaking of Vesuvius, Htna, and Santorin, and shall now merely add, that, in 1538, the whole coast, from Monte Nuovo to beyond Puzzuoli, was up- raised to the height of many feet above the bed of the Medi- terranean, and has since retained the greater part of the ele- vation then acquired. The proofs of these remarkable changes of level will be considered at length when the phe- nomena of the temple of Serapis are described.* Volcanos of the Phlegrean Fields.—lmmediately adjoining Monte Nuovo is the larger volcanic cone of Monte Barbaro (2, fig. 63 p. 608), the ‘Gaurus inanis’ of Juvenal—an ap- pellation given to it probably from its deep circular crater, which is about a mile in diameter. Large as is this cone, it was probably produced by a single eruption ; and it does not, perhaps, exceed in magnitude some of the largest of those * See Chap. XXIX. iy qurow pss mdant +f , : | gh the Fr va calle wer. Ye var has wutain arsed | Cu. XXIV.] VOLCANOS OF THE PHLEGRAIAN FIELDS. Gy formed in Ischia, within the historical era. It is composed chiefly of indurated tufa like Monte Nuovo, stratified con- formably to its conical surface. This hill was once very cele- prated for its wines, and is still covered with vineyards; but when the vine is not in leaf it has a sterile appearance, and, late in the year, when seen from the beautiful Bay of Baiz, it often contrasts so strongly in verdure with Monte Nuovo, which is always clothed with arbutus, myrtle, and other wild evergreens, that a stranger might well imagine the cone of older date to be that thrown up in the sixteenth century.* There is nothing, indeed, so calculated to instruct the geologist as the striking manner in which the recent volcanic hills of Ischia, and that now under consideration, blend with the surrounding landscape. Nothing seems wanting or re- dundant ; every part of the picture is in such perfect harmony with the rest, that the whole has the appearance of having been called into existence by a single effort of creative power. Yet what other result could we have anticipated if nature has ever been governed by the same laws? Hach new mountain thrown up —each new tract of land raised or depressed by earthquakes—should be in perfect accordance with those previously formed, if the entire configuration of the surface has been due to a long series of similar dis- turbances. Were it true that the greater part of the dry land originated simultaneously in its present state, at some era of paroxysmal convulsion, and that additions were after- wards made slowly and successively during a period of comparative repose; then, indeed, there might be reason to expect a strong line of demarcation between the signs of the ancient and modern changes. But the very continuity of the plan, and the perfect identity of the causes, are to many a source of deception; since by producing a unity of eifect, they lead them to exaggerate the energy of the agents which operated in the earlier ages. In the absence of all historical information, they are as unable to separate the dates of the origin of different portions of our continents, ilton (writing i in 1770) says, Phlegreei, p. 69. This remark was no Ham ‘the new mountain produces as yet but longer applicable when I saw it, in a very slender yegetation’—Campi 1828. 618 MODERN ERUPTIONS OF VESUVIUS. (Cx. XXIV. as the stranger is to determine, by their physical features alone, the distinct ages of Monte Nuovo, Monte Barbaro, Astroni, and the Solfatara The vast scale and violence of the volcanic operations in Campania, in the olden time, has been a theme of decla- mation, and has been contrasted with the comparative state of quiescence of this delightful region in the modern era. Instead of inferring, from analogy, that the ancient Vesuvius was always at rest when the craters of the Phlegreean Fields were burning—that each cone rose in succession,—and that many eyes and often centuries, of repose intervened between different eruptions,—geologists seem to have generally con- ject moan that the whole group sprung up from the ground at once, like the soldiers of Cadmus when he sowed the dragon’s teeth. As well might they endeavour to persuade is that on these Phlegrean Fields, as the poets feigned, the giants warred with Jove, ere yet the puny race of mortals were in being. fodern eruptions of Vesuvius.—For nearly a century after ihe birth of Monte Nuovo, Vesuvius continued in a state of tranquillity. There had then been no violent eruption for 492 years; and it appears that the crater was then exactly in the condition of the present extinct voleano of Astroni, near Naples. Bracini, who visited Vesuvius not long before the eruption of 1631, gives the following interesting descrip- tion of the interior :—‘ The crater was five miles 3 in circum- ference, and about a thousand paces deep: its sides were covered with brushwood, and at the bottom a was a plain on which cattle grazed. In the woody parts wild boars fre- quently harboured. In one part of the plain, covered with ashes, were three small pools, one filled with hot and bitter water, another salter than the sea, and a third hot, but taste- less.* But at length these forests and grassy plains were consumed, being suddenly blown into the air, and their ashes scattered to the winds. In December, 1631, seven streams of lava poured at once from the crater, and jrexiowed several villages on the flanks and at the foot of the mountain. | ; * Hamilton’s Campi Phlegrei, folio, vol. i. p. 62; and Brieslak, Campanie, tome 1. p. 186. rere ytaid- amie: ppan? ’ On. XXIV.] MODERN ERUPTIONS OF VESUVIUS. 619 Resina, partly built over the ancient site of Herculaneum, was consumed by the fiery torrent. Great floods of mud were as destructive as the lava itself,—no uncommon occur- yence during these catastrophes; for such is the violence of yains produced by the evolutions of aqueous vapour, that torrents of water descend the cone, and becoming charged with impalpable volcanic dust, and rolling along loose ashes, acquire sufficient consistency to deserve their ordinary appel- lation of ‘aqueous lavas.’ A brief period of repose ensued, which lasted only until the year 1666, from which time to the present there has been a constant series of eruptions, with rarely an interval of rest exceeding ten years. During these three centuries, no ir- regular volcanic agency has convulsed other points in this district. Brieslak remarked, that such irregular convulsions had occurred in the Bay of Naples in every second century ; as, for example, the eruption of the Solfatara in the twelfth ; of the lava of Arso, in Ischia, in the fourteenth; and of Monte Nuovo in the sixteenth: but the eighteenth has formed an exception to this rule, and this seems accounted for by the unprecedented number of eruptions of Vesuvius during that period; whereas, when the new vents opened, there had always been, as we have seen, a long intermittence of activity in the principal volcano. CHAPTER XXYV. VOLCANIC DISTRICT OF NAPLES—continued. DIMENSIONS AND STRUCTURE OF THE CONE OF VESUVIUS—FLUIDITY AND ——ORIGIN AND COMPOSITION OF THE MATTER ENVELOPING HERCULANEUM AND POMPEII—CONDITION AND CONTENTS OF THE BURIED CITIES—SMALL NUMBER OF SKELETONS—STATE OF PRESERVATION OF ANIMAL AND VEGE- TABLE SUBSTANCES—ROLLS OF PAPYRUS—STABIZZ—TORRE DEL GRECO— CONCLUDING REMARKS ON THE CAMPANIAN VOLCANOS. Structure of the cone of Veswvius.—ButwEEN the end of the eighteenth century and the year 1822, the great crater of Vesuvius had been gradually filled by lava boiling up from below, and by scorie falling from the explosions of minor mouths which were formed at intervals on its bottom and sides. In place of a regular cavity, therefore, there was a rough and rocky plain, covered with blocks of lava and sco- rie, and cut by numerous fissures, from which clouds of vapour were evolved. But this state of things was totally changed by the eruption of October 1822, when violent ex- plosions, during the space of more than twenty days, broke up and threw out all this accumulated mass, so as to leave an immense gulf or chasm, of an irregular, but somewhat elliptical shape, about three miles in circumference when measured along the very sinuous and irregular line of its extreme margin, but somewhat less than three quarters of a mile in its longest diameter, which was directed from N.E. to S.W.* The depth of this tremendous abyss has been ale estimated ; for fronr the hour of its formation it Account of the Eruption . Ve- Serope, Esq., Journ. of Sci. &e. vol. xv. suvius in October 1822, by Meee oy IAS * ptt Pe io ( espl oo ge 3508 ee omate ly nets all jai’ gure me soar sty mdu ged in bi it) R Cop TY (x. XXV. J STRUCTURE OF THE CONE OF VESUVIUS. 621 diminished daily by the dilapidation and falling in of its sides. tt measured, at first, according to the account of some au- thors, 2,000 feet in depth from the extreme part of the exist ing summit; * but Mr. Scrope, when he saw it, soon stat the eruption, estimated its depth at less than half that amount. More than 800 feet of the cone was carried away by the explosions, so that the mountain was reduced in height from about 4,200 to 3,400 feet.+ As we ascend the sloping sides, the volcano appears a mass of loose materials—a mere heap of rubbish, thrown together without the slightest order; but on arriving at the brim of the crater, and obtaining a view of the interior, we are agree- ably surprised to discover that the conformation of the whole displays in every part the most perfect sy mmetry and ar- rangement. ‘The materials are disposed in regular strata, slightly undulating, appearing, when viewed in front, to be disposed in horizontal planes. But, as we make the circuit of the edge of the crater, and observe the cliffs by which it is encircled projecting or receding in salient or retiring angles, we behold transverse sections of the currents of ies and beds of sand and scoriw, and recognise their true dip. We then discover that they incline outwards from the axis of the cone, at angles varying from 25° to 40°. The whole cone, in fact, is composed of a number of concentric coatings of alter- nating lavas, sand, and scoria. Every shower of ashes Eich, has fallen from above, and every stream of lava de- scending from the lips of the crater, have conformed to the outward surface of the hill, so that one conical envelope may be said to have been successively folded round another, until the aggregation of the whole mountain was completed. The marked separation into distinct beds results from the differ- ent colours and degrees of coarseness in the sands, scoris, and lava, and the alternation of these with each other. The gteatest difficulty, on the first view, is to conceive how so much regularity can be produced, notwithstanding the un- equal distribution of sand and scori, driven by prevailing r. Forbes, Account - Mount le p. 195. Oct. 1828. vita Edin. Journ. of Sci. No. xvi fT Ibid. p. 195. 622 STRUCTURE OF THE CONE OF VESUVIUS. [Cr. XXV. winds in particular eruptions, and the small breadth of each sheet of lava as it first flows out from the crater. But, on a closer examination, we find that the appearance of extreme uniformity is delusive; for when a number of ae thin out gradually, an d at different points, the eye does not without difficult ty recognise the termination of any one nae but usually supposes it continuous with some other, which at a short distance may , lie precisely in the same plane. The difficulty, moreover, of folteaiae any given layer is in- creased by its undulating form, produced by the moulding of recessive layers on the outer sides of a cone, which can never preserve perfect symmetry owing to its irregular mode of growth. As countless beds of sand and scorize constitute the greater part of the whole mass, these may sometimes mantle continuously round the whole cone; and even lava streams may be of consider able breadth when first they over- flow, and since, In some e eruptions, a considerable part of the upper portion of the cone breaks down at once, may form a sheet extending as far as the spaee which the eye usually takes in, in a single section. The high inclination of some of the beds, and the firm union of the particles even where there is evidently no ce- ment, is another striking feature in the volcanic tuffs and breccias, which seems at first not very easy of explanation. But the great eruption of 1822 afforded ample illustration of the manner in which these strata are formed. Fragments of lava, scorie, pumice, and sand, when they fall at slight dis- tances from the summit, are only half cooled down from a state of fusion, and are afterwards acted upon by the heat from within, and by fumeroles or small crevices in the cone through which hot vapours are disengaged. Thus heated, the ejected fragments cohere together strongly; and the whole mass acquires such consistency in a few days, that fragments cannot be de ached witho jak a smart blow of the hammer. At the same time sand and scorie, ejected to a sins distance, remain incoherent.* Sir William Hamilton, in his description of the eruption of 1779, says, that jets of liquid lava, mixed with stones oa Monticelli and Covelli, Storia di Fenon. del. Vesuy. in 1821-23. pilot occa ‘ay half tl he same : RO f the | ki fait had mit issu tnountay i] On XXV.] FLUID LAVA. 698 scorie, were thrown up to the height of an least 10,00€ feet, having the appearance of a column of fire.* Some of these were directed by the winds towards Ottajano, and. some of them, falling almost perpendicularly, still red-hot and liquid, on Vesuvius, covered its Whole cone, part of the mountain of Somma, and the valley (the Atrio) between them. The falling matter being nearly as vividly inflamed as that which was continually issuing fresh from the crater, formed with it one complete body of fire, which could not be less than two miles and a half in breadth, and of the extra- ordinary height above mentioned, castin g a heat to the dis- tance of at least six miles round it. Dr. Clarke, also, in his account of the eruption of 1793, says that millions of red-ho} LLOU stones were shot into the air full half the height of the cone itself, and then bending, fell all round in a fine arch. On another occasion he says that, as they fell, nearly half the cone with fire. The same author has also described the different appe ance of the lava at its source, and at some distance from when it had descended into the plains below. At the point where it issued, in 1793, from an arched chasm in the side of the mountain, the vivid torrent rushed with the velocity of a flood. It was in perfect fusion, unattended with any scorize on its surface, or any gross materials not in a state of Cor plete solution. It flowed with the translucency of honey, ‘in regular channels, cut finer than art can imitate, and glowing with all the splendour of the sun,’—< Sir William Hamilton,’ he continues, ‘ had conceived that no stones thrown upon a current of lava would make any impression. I was Soon convinced of the contrary. Light bodies, indeed, of five, ten, and fifteen pounds’ weight, made little or no im- pression even at the source ; but bodies of sixty, seventy, and eighty pounds were seen to form a kind of bed on the surface of the lava, and float away with it. A stone of 800 ewt., that had been thrown out by the crater, lay near the source of the current of lava: I raised it upon one end, and then let it fall upon the liquid lava; when it gradually sunk beneath the Surface, and disappeared. If I wished to describe the manner they covered ar- sa 1t, Yy n- * Campi Phlegrei. 624 FLUID LAVA. [Cu. XXV. in which it acted upon the lava, I should say that it was like a loaf of bread thrown into a bowl of very thick honey, which eradually involves itself in the heavy liquid, and then slowly sinks to the bottom. ‘The lava, at a small distance from its source, acquires a darker tint upon its surface, is less easily acted upon, and, as the stream widens, the surface, having lost its state of per- fect solution, grows harder and harder, and cracks into in- numerable fragments of very porous matter, to which they give the name of scoriz, and the appearance of which has led many to suppose that it proceeded thus from the moun- tain. There is, however, no truth in this. All lava, at its first exit from its native volcano, flows out in a liquid state, and all equally in fusion. The appearance of the scoriz is to be attributed only to the action of the external air, and not to any difference in the materials which compose it, since any lava whatever, separated from its channel, and exposed to the action of the external air, immediately cracks, becomes porous, and alters its form. As we proceeded downward, this became more and more evident; and the same lava which at its original source flowed in perfect solution, un- divided, and free from incumbrances of any kind, a little farther down had its surface loaded with the scoriz in such a manner, that, upon its arrival at the bottom of the moun- tain, the whole current resembled nothing so much as.a heap of unconnected cinders from an iron-foundry.’? In another place he says, that ‘ the rivers of lava in the plain resembled avast heap of cinders, or the scoriz of an iron-foundry, roll- ing slowly along, and falling with a rattling noise over one another.’* Von Buch, who was in company with MM. de Humboldt and Gay-Lussac, describes the lava of 1805 (the most fluid on record) as shooting suddenly before their eyes from top to bottom of the cone in one single instant. Pro- fessor J. D. Forbes remarks that the length of the slope of the cone proper being about 1,300 feet, this motion must sorrespond to a velocity of many hundred feet in a few seconds, without interpreting Von Buch’s expression literally. The same lava, when it reached the level road at Torre del * Otter’s Life of Dr. Clarke. 1 1834, 1 uh nistal table du Ya fom { ‘te ‘plen ‘Med eit Cu. XXV-] FLUID LAVA.—ROPY SCORLE. 625 hea Greco, moved at the rate of only eighteen inches per minute, or three-tenths of an inch per second.* ‘ Although common Java,’ observes Professor Forbes, ‘is nearly as liquid as melted jron, When it issues from the orifice of the crater, its fluidity rapidly diminishes, and as it becomes more and more dened by the consolidated slag through which it has to force its way, its velocity of motion diminishes in an almost incon- ceivable degree ; and at length, when it ceases to present the slightest external trace of fluidity, its movement can only be ascertained by careful and repeated observations, just as in the case of a glacier.’ + It appears that the intensity of the light and heat of the lava varies considerably at different periods of the sg eruption, as in that of Vesuvius in 1819 and 1820, when Sir H. Davy remarked different degrees of vividness in the white heat at the point where the lava originated. t When the expressions ‘flame’ and ‘smoke’ are used in describing volcanic appearances, they must generally be understood in a figurative sense. We are informed, indeed, by M. Abich, that he distinctly saw, in the eruption of Vesu- vius in 1854, the flame of burning hydrogen ; § but what is usually mistaken for flame consists of vapour or scorie, and impalpable dust illuminated by that vivid light which is emitted from the crater below, where the lava is said to clow with the splendour of the sun. The clouds of apparent smoke are formed either of aqueous and other vapour, or of finely comminuted scoriee. Ropy scorie.—In their descriptions of lava, geologists often speak of ‘ropy scorie,’ for sometimes a large portion of the scoriform surface assumes the appearance of coils of cable. This structure I saw very conspicuously displayed by the lava of 1857, where it had poured over from the lip of the crater and descended the N.N.E. side of the cone. There were no loose fragments of scorie upon it, and the bur- ame Surface had the form partly of ropes and partly of the roots of trees, Occasionally we may observe such lavas on Hina § Bulletin de la Soe. Géol. de France, tom. vil. p. 43; and Illustration of Ve- suvius and Etna, p. 3. * Phil. Trans, 1846, p. 154. + Ibid. p. 148. . SS 626 ROPY SCORIA. [Cu. XXV. and Vesuvius, especially near the points from which they issued, exhibiting, for a short distance, flattened spaces a few feet or yards wide, on which the rope-like coils are arranged one within another, all bending the same way, as a bc in Fig. 66. a a eae fig. 66. I had an opportunity in 1858 of seeing the manner +n which this structure originates. The highest crater of Vesuvius was then tranquil or only emitting steam ; but half way down the mountain on the side towards Naples and below the Piano di Ginestra, were two cones which had re- cently been thrown up. Near the base of one of these was a grotto, from which lava had been flowing without inter- mission for several months, and was still pouring out in a perfectly liquid state. It had built up a ridge between 10 and 15 feet in height, at the top of which it had formed a straight canal 5 feet wide. At the point where it issued from the grotto, it seemed as fluid as water and was at a white heat. In order to enable me to approach near enough to watch its movements without being scorched, my guides held up between me and the fiery stream a bull’s-hide screen pierced with small holes through which we looked. ‘At the distance of about two yards from the grotto, the lava flowing with great velocity in the canal, began to turn from white to red, and a few feet farther on it acquired a darker colour, and many small separate pieces of scorie were seen floating on its surface, showing that solidification had commenced. About four yards from the point of efflux, the surface of the stream had already become black, and the de- tached pieces of scoriz had begun to be pressed against each other so as to unite, and they soon became welded together into continuous ropy coils, each set bending forward in the middle where the stream ran fastest, and fitting one within the other, as in fig. 66. Their successive formation and (Cu. XXV.] ' RECENT DIKES. 627 arrangement reminded me of the manner in which wreaths of foam collect on a river below a cataract or the piers of a bridge, and being carried by a current or by the wind against a bank or island, retain for some time the marks of having been formed on the surface one after the other. The course of a lava-stream may always be known by the direc- tion in which such coils are bent. Dikes in the recent cone, how formed.—The inclined strata before mentioned which dip outwards in all directions from the axis of the cone of Vesuvius, are intersected by veins or dikes of compact lava, for the most part ina vertical position. In 1828, these were seen to be about seven in number, some of them not less than 400 or 500 feet in height, and thinning out before they reached the uppermost part of the cone. Being harder than the beds through which they pass, they have decomposed less rapidly, and therefore stand out in relief. When I visited Vesuvius, in November 1828, I was prevented from descending into the crater by the constant ejections then thrown out; so that I got sight of three only of the dikes; but Signor Monticelli had previously had drawings made of the whole, which he showed me. The dikes which I saw were on that side of the cone which is encircled by Somma. The eruption before mentioned, of 1828, began in March, and in the November following the ejected matter had filled up nearly one-third of the deep abyss formed at the close of the eruption in 1822. In November I found a single black cone at the bottom of the crater continually throwing out scorize, while on the exterior of the cone I observed the lava of 1822, which had flowed out six years before, not yet cool, and still evolving much heat and vapour from crevices. Hoffmann, in 1832, saw on the north side of Vesuvius, hear the peak called Palo, a great many parallel bands of lava, some from 6 to 8 feet thick, alternating with scoriz and conglomerate. These beds, he says, were cut through by many dikes, some of them 5 feet broad. They resemble those of Somma, the stone being composed of grains of leucite and augite.* * Geognost. Beobachtungen, &c. p. 182. Berlin, 1839. 8 5 2 628 RECENT DIKES. [Cu. XXV. There can be no doubt that the dikes above mentioned ve been produced by the filling up of open fissures with ha but of the date of their formation we know liquid lava ; nothing fat 79, and, relatively speaking, that they are more modern than all the lavas and scorize which they intersect. A consider- able number of the upper strata are not traversed by them. That the earthquakes, which almost invariably precede erup- tions, occasion rents in the mass, is well known; and, in 1822, three months before the lava flowed out, open fissures, evolving hot vapours, were numerous. It is clear that such s must be injected with melted matter when the column a rises, so that the origin of the dikes is easily ex- plained, as also the great solidity and crystalline nature of the rock composing them, which has been formed by lava cooling slowly under great pressure. Scacchi, in his detailed narrative of what happened from day to day in the eruption of 1850, gives an account of a long linear opening or fracture on the N.N.E. side of the cone of Vesuvius, from one part of which lava issued. This chasm marked, no doubt, the site of what has now become’ a dike traversing the mountain. When Signor Scacchi accompanied me to the Atrio, in 1858, the chasm alluded to was still visible on the slope of the cone, though even then it had been partly filled by the lava of 1857, which descending from the lip of the crater had flowed into it. It has been suggested that the frequent rending of volcanic cones during eruptions may be connected with the gradual and successive upheaval of the whole mass in such a manner as to increase the inclination of the beds composing the cone; and in accordance with the hypothesis before proposed for the origin of Monte Nuovo, Von Buch supposes that the present cone of Vesuvius was formed in the year 79, not by eruption, but by upheaval. It was not produced by the repeated superposition of scoriv and lava cast out or flowing from a central source, but by the uplifting of strata pre- viously horizontal. The entire cone rose at once, such as we now see it, from the interior and middle of Somma, and has rent of lav ther than that they are all subsequent to the year © ilen ren ih which - ALev mo “~ ty iD y, Peay, gradtil on. XXV.] RECENT DIKES. 629 since received no accession of height, but, on the contrary, has ever since been diminishing in elev: ution.* I shall endeavour to show that this hypothesis of Von Buch, whether applied to the modern cone of Vesuvius or to the more ancient cone called Somma, is wholly untenable. But before enlarging on this topic, I may mention some facts recorded by M. Abich in his account of the Vesuvian erup- tions of 1833 and 1834, because they might seem at first sight to favour the possibility of such a mode of origin.t In the year 1834, the great crater of Vesuvius had been filled up nearly to the top with lava, which had consolidated and formed a level and unbroken plain, except that one small cone of scorize had been thrown up, which rose in the middle of the plain likean island inalake. At length this flat area of lava was broken by a fissure which passed from N.E. to §.W., and along this line a great number of minute cones emitting vapour were formed. The first act of formation of these minor cones consisted, according to Abich, of a partial upheaval of beds of lava previously horizontal, and which had been rendered flexible by the heat and tension of elastic fluids, which, rising from below, escaped from the centre of each new monticule. There would be’ considerable analogy between this mode of origin and that ascribed by Von Buch to Vesuvius and Somma, if the dimensions of the upraised masses were not on so different a scale, and if it was safe to reason from the inflation of bladders of half-fused lava, from 15 to 25 feet in height, to mountains attaining an altitude of several thousand feet, and having their component strata strengthened by intersecting dikes of solid lava. t the same time M. Abich mentions, that when, in August 1834, a great subsidence took place in the platform of lava within the great crater, so that the structure of the central cone was laid open, it was seen to have been evidently formed, not by upheaval, but by the fall of cinders and scoriee which had been thrown out duri ing successive eruptions. tf Mr. Scrope, writing in 182 7, attributed the formation ofa * Von Buch, escrip. Phys. des Iles Géol. sur le Vésuve et l'Htna. Berlin, Canaries, p. 342. Pa aris, 1836. _ 1837. r4 bieh, Vues Illust. de Phénom. } Ibid. p. 2. 630 ORIGIN OF THE CONE OF VESUVIUS. [Cu. XXV. volcanic cone chiefly to matter ejected from a central orifice, but partly to the injection of lava into dikes, and ‘to that force of gaseous expansion, the intensity of which, in the central parts of the cone, is attested by local earthquakes, which so often accompany eruptions.’* The inclination of some of the lavas may, no doubt, have been modified in some cases during the rending and dislocation of the cone, but I do not believe, any more than the author just cited, that such disturbances have-played a conspicuous part in giving to voleanic mountains the configuration, whether external or internal, by which they are distinguished. Previous to the year 79, Vesuvius appears, from the descrip- tion of its figure given by Strabo, to have been a truncated cone, having a level and even outline as seen from a distance. That it had a crater on its summit, we may infer from a passage in Plutarch, on which Dr. Daubeny has judiciously commented in his treatise on voleanos.t The walls of the crater were evidently entire, except on one side, where there was a single narrow breach. When Spartacus, in the year 72, encamped his gladiators in this hollow, Clodius, the praetor, besieged him there, keeping the single outlet carefully guarded, and then let down his soldiers by scaling ladders over the steep precipices which surrounded the crater, at the bottom of which the insurgents were encamped. On the side towards the sea, the walls of this original cavity, which must have been three miles in diameter, have been destroyed, and Brieslak was the first to announce the opinion that this destruction happened during the tremendous eruption which occurred in 79, when the new cone, now called Vesuvius, was thrown up, which stands encircled on three sides by the ruins of the ancient cone, called Monte Somma. In the annexed diagram (fig. 67) it will be seen that on the side of Vesuvius opposite to that where a portion of the ancient cone of Somma (a) still remains, is a projection (0) called the Pedamentina, which some have supposed to be part of the circumference of the ancient crater broken down towards the sea, and over the edge of which the lavas of the * Geol. Trans. 2nd series, vol. 11. p. 341. + 2d edit. 1848, p. 216. ORIGIN OF THE CONE OF VESUVIUS. 63] Cu. XXV.] modern Vesuvius have poured ; the axis of the present cone of Vesuvius being, according to Visconti, precisely equidistant from the escarpment of Somma and the Pedamentina. In the same diagram I have represented the slanting beds Fig. 67. x aN > < se 286 Hssex, inroads of sea on coast of, 521 Estuaries, eat Se up of, 516 =) 2 Ou i=] 2 of, 598 Ss a mate of fo =a 180 as ON! 6 y Biitedsioudis down by Gan- ges, pei 661 FOR Excavation of valleys, 356 — ricity, pemaieaned.: of variations of, ike earth’s orbit, 269 fine Sound, glacier of, 208 | | | EF ALCONER, Dr., on peat near einige: 475 — —— range of elephant, 1 nalia of sor 22 Hille 201 Falkland 1 Tsles, faun Falloppio on _— cone manele 33 any yf Niagara, 358 aluns of es aine, 200 ar aday, 1 water of Geysers, 409 reg ae ion, 373 Nasi aes on on formation of ground-ice, 367 7, J., on Scotch floods, 350 Fa s, gradual formation of, 120 Pes Figo onhaugh on Red eg swamps, 45 Fels ce vege sition of, Fergusson, Mr., acto of no ground,’ 476 — formation of jheels, 478 Reis, preponderance of, in Coal period, 226 Ferruginous at dea tion o f coast 509 Fish, Fluviatile fossi of Vises, 464 — fossil, their pearing on progression, 153 nber of British s; species in » Devonian, 154 — found alive in : Artesian wells, 393 i Dr., 0 Ss} ine’s. 4 87 age ny vatitale a as con of climate, _ a pion evidence of former tropical clim Floods 1 by bursting of lakes, 454 — of a and, 2 apts a, me aire valley, 352 Tivoli, 354 rl EN blocks sass ia in, 209 Folkesto 1 nts of sea 528 or sition elsciers, 370 — —— snow-line in northern hemisphere, 24 ee ie - soe stream, 245 uid lava, 625 — ie od on in me of the drift, 193 — exc ee — prese sta ants proving a glacial period, 198 oe ammer, Dr on ice, 385 boulder drifted by 462— attraction nae ce, 290 Mississippi, 443 i delta, 45) whether by Porshey on cur ea » _-— were island of Mississippi, 450 © ° = Ba I uu w = nm wn 4 mS So Rice 4 ° | 662 Fortis on See geology, 6 fe nd a on fossil fish, 6 Rosier series, causes : breaks in, 317 = , table of, 189 econcerninsa B43} s Fos ae arly sp Fossil hella, height of, in Alps, Andes, and Himalaya, 1 Fracastoro, vie f, ¢ France, waste of coast in, 547 Freyberg, sc , 68 iA ns wave eae ote bore,’ in, 560 pri ints Fundy, sia ALAPAGOS ea ys reptiles of, 221 n borings in delta of, 478 and Bra imayoota mud o Rees 480 wn b Gaps, causes of, in fossilif a, 318 Gastaldi on Miocene blocks of the Superga ae rena an A., on second advance of glaciers, Gemmellaro on Etna eruption, 357 nee ell? s istration of Moro, 52—56 Geneva, — “— sate de derpesiy in, 417 > dir in, 508 ee cause change of climate more influential than 7 al, 278 predomir in g climate, 283 Geography, — in, in occas and Primary periods, 2 — former ves in, gees affecting climate, 1 — line in, revealed by geolog, y; 248 nets 4 saat § istorical pro s of, po II. to V. — specuiative listen of early, 324 — defined, 1 — compared to History, 2, 4, 92 — new school of, 85 judic es which have Sea 90 U.S., new ravine formed i in, 344 of, 22 celand, 409 Gibbosity of sap in ve 610 Gibraltar, Straits of, 5 Glacial epoch, na of leve — — changes s1 since, 194 — period, we apheet 288 —296 | pe INDEX. I HAL Dy u Glacial period, ¢ 300 a on nse fate vine before and after, identi io eal, 31 ih 6l/ i ~ enduring through all phases of preces- ae x ; sio a — a coal fi ss! ———on valley of iar Channel, 532 -— [ntergiat k Bay submerged forest, 545 -— Oeningh Golden en eae aes e of, whence derived, 13 _- Surturbt Goodwin te 525 id Gould’s s oa Mis eran delta, 1764, 461 Granite, ticki coics of, 4 — formed at different —— — veins observed pe aoa in iene Tilt, of the Hartz, Werner on, 70 Greece, traaitions of deluges in, 594 eek A Arch in, voleanos of the, 592 — ck geology Gre Bay ne on , aL fish of Vicksburg Gr Baad sinking of land in, 131 why sal than i aides 237 @ Ste =e bed, 5 — effects of, 566 Grotto del Cane, carbonic acid in, 411 Ground ice, 866 orting rocks in eee 885 a, mS ° fessor, cited, 1 Guinea current, 500 iiscardi, Signor, on stony beds of Somma, , 634 Gulestrean, causes and velocity of, “ee and warming effects of, 2 eas Mr, on range of eee a Guyot, M., on glacier motion, yaa. Jand gained from lake of, 552 Habkeren blocks, disputed origin of, 20 Hail, ee Bs on flood of Bagnes, 353 ———-—t rade winds, 497 —--—--— pine of New York, 359, 361 — — — — waste of Mississippi van 444 — snags of Mississippes aes? Sir J James, 3} “ ifted by , of, 502 jgiD of, INDEX. uf ot Mr. W. J.,on i eolondoa in Smyrna, _ Sir W. on formation of Monte Nuovo, 607; = op ormulaneum., ieee n 779, 622 Hampshire eee of coas ti ce artt, Mr. Road onian Shacnaa 157 rite of, 70 oe wearing aw ea S oast near, 52 im e of diffusion over >the globe, 2 _ Pe ent of, 2 a = whoth er gradual decline of, on globe, Heath, Mr., on effect o poise} ice-cap, 29 Hector, Ho on sudd ig of New i. Heer, = fe sor, ited an8 —on arct —— coa i ssils of ae Saha 225 Be eelacial p iod, 196 — — Oeninghen ‘ues a, ae of Tool 202 -— Pe eaosting of cry. sae ramous plants, 116 oe and Sandy Island, view of, 555 oads of sea on, 554 Hennepin and Kalm on Niagara Falls, 360 erculaneum, 646 ass enveloping, bag ts di in, 647 a f cliffs in, 523 Snrturbrand erne Bay, Herodotus on marine fossils of N Herschel, Sir J., on cli gg basheaty astro- nomical causes, 269, 2 s drawing s Botzen earth-pil- — ——-— heating effect of land under sun- shine, 276 ——-—-— light and heat received by the earth, 270 bone ae ature of space, 279 oretical oe of climate “north aud a. ‘ats or, 277 ariation of ee of ecliptic, 282 - Sir] W. on motion of earth through space, Hewitt, Captain, on channel formed by shift- ing of sand-banks, 5 ibbert, Dr., 34 er washed out of Shet- land Isles, 50 Hilgard on sae Pliocene? of Mississippi delta, 448, 460 —— fossil remains of New Orleans Artesian eniiicn, oe of fossil shells in, 144 Hindoo cosm Hippo iaotis tooth of, in tig ‘aes 438 Hoff, Von, on level of Cas Hoffmann on lava of Vesuvi fas, - Holbach against diluvial arb 50 Holland, inroads of the sea in, 55% —557 Holyhead, submerged peat-bed at, 545 668 ICE Hooke on duration of species, 41, 42 — his diluvial theory, 44 — on fossil turtles implying high tempera- ture, 174 eet on a carried - bint iets 1 delta of Ga 470— n India a, 880—332 — snow a ecking radiation of heat, 285 Gckine on oe of climate from geogra- phica ah ca 261 tbe: 372 — hes t rec sane Ae earth in passing ud, 434 in me Ww latitudes, 246 e North America, 352 Hue, M., on yaks frozen in ice in Tibet, 190 prs on spectrum analysis of a variable star, Humes remains, their pepe 166 Humber, ‘ warping’ of the, 570 Husnbol on average rainfall, 329 sses frozen ade 189 e ee eee erie ne ar pthque rik ce, — en s eapeleat of rleaie action, 5 ath 1 di a n of heat over the globe, 234 —_ ios seth apreiiiee he iiepiee e, 284 _-— paler gration = anima 79 Alps, 287 ate ien, General, nites 449 Humphreys and Abbot, MM., Mississippi, 442—445 rsaempateoie carried down by Mis- sippi, 453—45 an = Mr. T. Sterry, on petroleum, 413 Hurst Castle shingle bank, 531 ee eens Ws Moses’s Principia, 49 1 Geology from Cosmo- report on gony, 4 — theory of, 73, ae 83 Hypogene rocks, 1 Shes ose imbedded in, floating in. sea of em cl ene 216 — solid sana transported by, 363 — thickness and extent of polar, 285 — -action and erratics, 108 —— in Hocene py 209 — — in Miocene times, 205 supposed, in Per mian period, 222 n period, 2 I s — carrying a i decparys carrying blocks, 379 1g south, a cause of cold, 245 i -cap, ee yable thickness of polar, 288 = tis po eB ateae ing the level of the ocean, i Ae bani ay oie poles, in the Glacial period, 282 — effect of, on the level of the ocean, 289, 290 Ice-streams in Baffin’s Bay, 288 664. INDEX. | yor ICE MAC ¥ gl, Iceland, wig a woe on, 245 Lake, dammed up by a glacier, 376 je tock: — Miocer of, 20 — deltas, 417, 421 yom — geysers ne hie Lakes formed in Louisiana, 454 pie sie ] sie pbarsetn in lias, lat. 77° N., 219, 282 Lamarck, his theory of progression, 147 jor ve. Ictis of Diodorus Siculus, 542 Land, as of, in distributing heat, 2 276 yes ae, action. See Volcanic. effect of, in warming the atmosphere, a Net auses, antagonistic to running water, 305, 237, a h itd <7 wi — height of, compared to spit of sea, 265 ose ik rees, supposed ene pres of, 117 — map showing antipodal, 2 sens : TInfusorial tuff of Pompe — now abnormal at sa poles 247 yspsets™ Tnland seas, deltas of, es i 421 — proportion of, to sea in tropics, 247 met, h Inorganic causes of change, 327 a rte of, which hte favour warm yojoli 08 " Insects, in Devonian strata, 157 climate, - yglet, CaP" ‘Insular’ clima tes, 239 — rise of, in Sweden, 121, yonalia, Inter-glacial per iods, aa — rise — depression of, sie lifes pa Ischia, drawing o region of, 601 — and sea, a normal shake ce considered, 262 _ fossil, 28 | —h not springs hs 409 — and see es present unequal distribution of, _of Mississ 20 ions of, 598, 605 257 _guecessiv' Is] and, new, in “Medit erranean, 1707, 51 Landslip in Dorsetshire, 536 jynmifer fi islands, a sie gee of, in Baltic, 554 La “ idslips on the hee 469 amoth ‘ pt cotland, 506 oods caused by, —— e nges, ats iaploe on no eration of globe, on d fos Isle of Wig ght, wi faa of its shores, 530 Lariviere, M., on ice-transported nie ks, 564: shat i 7 isothermal ange ba curves in Europe and Lassaigne, his analysis of ae mud, 433 - proba . Am Lauder, Sir T. D., on aoe: floods, ¢ Yu, ntrod —n acm e mean annual, 23 Lavas of Somma, slope of, 632, 638, 640 - durability Tsothermals, deflection ae in Glacial period, Ppa Se of i ee 638 Vanetho, 92 297 Lazzoro Moro. See Mo ” of chan italy, alternation of earthquakes hetween T eave es, fossil, of Casa ‘dar Acqua Somma, Syria and, 5 G34 Se ree — Pliocene strata of, 199 a os of 1756, 59 -— Ganges — early geologists of, 30, 5 Leibn origin of p primitive resin 40 -—jsother Ivory, vast stores of, in ane 185 pete eptiles of the Chalk, 214 -— Mississ Lena, fossil fens es on banks af ‘181, 183 ~— Siberia Leona rdo da a on fossil shells, 31 -—Yvoleani 3 bes MES, Sir iit on Dead Sea level, oR Leslie, Sir J., on heat received by poles and Tews q Sears k of tin dredged up i equator, 28 Ne wal —_— Falmouth — bow 541 Leslie, Sir J., on temperature of hottest hem Jamieson, _ glacier. ~ theory, 379 month in London, 294 ns Java, valley sola in, 589 Level of Dead Sea and Caspi Hississipp — volcanos in, 589 Leverrier’s paroles of ae of ~~ chang: Jones, Sir W., on Menv’s institutes, 7 earth’s orbit, 2 Petiod, 25: Jorullo, eruption of, 584 | Light, influence es ov pale 226 ~~ presen Jukes, Mr., on eiicenie te near Java, 589 | Linco aahioe: waste of ¢ 511 iad sea, 92 Jutland, inroads of sea in, 55 | Lindley, Dr., on fossil ee of Melville ~ideal, of Tslar a 225 %a, 263 17 AM! Lippi on Herculaneum and Pompeii, 643, Taps idea) ee sscioaes ae ee in, 58 646 8, Which Kaschnitz, Herr Von, on destr ses of Lichen. earthquakes at hia Neola K ee sc " me 399 f land and sea, 29 | pete sx on fossil shells, Wing fos ati on oscillations of land and sea, Ze ites. Kaup, Dr. gibbon, or long-armed ape, 200 | 7 se es of toner Valley sae ‘ea Se a C. = cited, 3 | el 1, Artesian well nea Vai Keill on W histon and Burnet, 49 Lonsmy mds Byer 2 af Post situ, 129 bi Kent, ee of sea on spo of, 522 ouisiana, formation of lakes in, Sten rane perner ling, fount, ated, Lome Ness, Suffolk, how SG 518, wets te King, Rev. S. W., on 1 Bocles Church, 518 aa. Of, ¢ ‘rwan, his geological essays, 52 Lunas, Sir J., on deposition of Nile mud, Ye ton of Koran, cosmogony of , 28 437 th On ip Kurile Isles, active ce in, 588 _ — — — term Neolithic, 176 — axis B Slay > i Fae BRADOR, rocks drifted by ice on, 384 2 ? io Ya. Rive Lagrange on limits of excentricity of Wace IOCENUS ye ly ei th’s orbit, 269 ticity of, 194 UDhig ered, % Ution of . 30 Pcs, 3 433 roles and - hottest ricity of Melville neil, 643, 1 gute INDEX. 665 MAC _ ae Dr., on voleanic line in Bay of engal, 5 stn, aul: oolitic fossils near the ole, 218 sackonni River, floods 188 WNab, Mr. J., his cae fs an iceberg, 77, 381 Madrid, New. See New Madrid. Magellan, Stra aits of, tides in, 493 Magnesia | deposited = springs, 897 Magnetism, solar, Mahomet, his eosmogony, 2 Majoli o 2 shells, 35 Mallet, Ca ptai n, on Trinidad petroleum, 414 Mam — : ec of, how far affecting rep- ile Xi = co = — fos cata ing on oe 158 — of ipo i loess — successive ‘ies ant of hay cad 163 Mammifer fossil of trias, 1 eae oo aim of the, ce nay cae on “egg 1866, 185 — probable food of, 187 Man, introduction oy and its effects, 167— _ sur a of bones of, 166 a e Baltic, 557 =e and Brahmapootra, 471 —-— therm lines, 2¢ — Mississ pi a ta, 448 — — Siberia, ee listrict of Naples, 559—579 — volcanos from Philippine Islands to Ben- gal, sede a . of mud-lumps of the Mississippi, —— Sah in es since the Eocene ae , 252 Sacer unequal distribution of land Pe sea, 258 — ideal, of normal distribution of land and sea, 2 Maps, ideal, showing position of land and sea, which might prod t f heat and co 66 Marine fossils, Greek nol as to, 19 Miarjelen See, or glacier-lake, 377 Mattioli on fossil organic shapes, 33 Medi a raines, 374 Sap depth ie e ae: Parties ei depths, temperature 562 - “oh of ee to Bed hg 6 — section of bas Meech on on increase 4 io by shortening of min S$, 278 —on solar tiation 284 Megna River, arm of Brahmapootra, 470 til Isiah, carboniferous fossi ei in, 225 Mem mputation of growth of Nile fe. #4 a Monita iustibutes 7,8 MUR i le Glace, width of, 870 Messina, tide in Straits of, 49; Me nse phic rocks, textureand origin of, 142 i 0, voleanos of, 58 Meyer, H. Von, on reptiles of aie | 219 Mic nell, oe Vv. ii on beet nina Microles scove A peer tiles 161 Middendot vated 925 m Siberian mammoth, 184—188 Milt a Haven, rise of tides at, 494 4, pene he W. A., on spectrum analysis of a var star 303 Miner Cc es acter of strata variations in, 309 — springs, ingredients of, ¢ inerals of Vesuvius, 632 pee fossil trees in arctic latitudes, 203 — Lower, strata of, 202 — Uy per, warm ee of, 199 ion in Mississipi, basin aha delta of, 440 ‘bluffs’ of the, 462 — vont = atin by sediment, 310 — diagram of banks of, 443 — sedin eet carried down by, 458 — curves of the, 442 — cuts-off of the, 346 — delta and erpoE plain of, 457 — — growth of, — sec ctio ot valey of, 464, — Va ile ve oess of, 46% — mud- Haas a mouths of, 447 — sunk country of, 4 ir of current ak Adi Mo el py 1} , 195 Mollusc, Tos as bearing on theory of pro- Moluccas, voleanos of the, Monkeys, grades of Eocene ee Miocene, 164 Monte . fossil fish of, 6 kes in, 6 ake on volcanos of Auv e, 73 e, J.C., Pea arith of fies effects oe exeotriiy, 293 bs on ‘Tite corals, 254: of polar ice-cap, 291 ee aines ae oe. explained, 374 Morlot, M.,on subsidence of bed of Adriatic, 425 — two glacial periods, 19 Maro Lanza, ae Seclogios a Medi: STR Mountain-chain e of; 121—13 —-— a seep and suede of, peg M of, 4: if, 2 pe oetoe ot the eneetir delta, 447 Murchison si 'R.. on Hartz Mountain, 71 of Russia, 251 ———on : Habkeren blocks, 209 — — — cited, 112, 251, 253 666 INDEX. M Murchison, Sir R., on extension of Siberia, 188 salen of Devonian, 320 vertin a Tivoli, 407 eee ar, ou Silver Pits and pees Bank, 5 eee Sasciatus, 159 Nia coast of, raised by an eruption, As at Needies of the Isle of fw i 5381 177 ists, Nero, wise cesco del, on — of Monte Newbold, if wees on mud vr Pee 431 clad Mavic, sunk country of, red sandstone, var — ages . = Ser eee of, 211, 224 — ferns in, 224 Niagara recession of eo of, 359 — view of the Fails of, 3. Nile mud, borings er ay . 435 — delta of, 431 se ian pon eH of, 115 orfolk, v sae we 51 at h Cap ie wet foxthen n hemisphere fore aie of, 174 the, 276 Marth and, destr uction of, by the sea, 557 Norwich onee situated on an arm of the sea, 6 Nova Scotia, distinct deposits of red marl in, f tides eat ode ae of, 209 Nuovo, Monte, internal talus of, 616 I, River, fossils on shores of, 181 e shells of, 467 Ocean, great depth of, a cause of slow geo- graphical change, et Odoardi on tertiary strata of Italy, 62 Qninghen, age ee flora of, 200 Ogygian deluge, 59% Old red sandstone, climate of ae of, 230 Olivi on deposits in Adriatic —_-— = il remains, 34 Omar on ‘ Retreat of the Sea,’ 28 Dallte fossils, Climate of, 218 Orbigny, M. A. de, on Pampean mud, 181 Orbit of the earth, how far excentric, and why is Organic life, pr Aa ene f Onsite remains, controver Sy ee, to origin nof, an cosmogon Orkney Isla i Ovid, sketch of P vthagorean doct nA Owen, Professor, on teeth of fag 187 P oe Raa on British foreign mam- and birds, _-— eae of p eee 155 — — — Polar ichthyosaurus, 21 — — — sub-classes of ue 165 — — cited, 214, 21 Pease on te or older stone age, cli- ate of, 1 mountai wihvien Mr, on shingle beaches, 5 531 Pa om a former submergence of isthmus of, irri in bay of, 496 Papyrus rolls in Pompeii, 650 g load oO le) n, 222 Peveely, Mr, on waste of Nae Sushite coast, -——— eae’ of bes Michael’s Mount, 542 P i ion of animals, 179 t 588 Perry, Alexis. | Peru, volcanos Pir he ore ie a flood, 11 etroleum springs, te ae Bucklandi, 160 ee ae = ,on gradual ace of species 3 n Sic Phillips, roto, on waste of Yorkshire coast, 51 Phlegreean ite lds, Moe eh = bee 616 Pie otra ae inflammable ight and size of Se ae 607 Pitch-le es of Trinidad, 414 Plants, fossil, their bearing on progression, 148 Foe rboniferous period, 224 virtue’ of earth, theory of, 20, 40 Pluche on the deluge, 50 bbe ds: on doctrines of Anaximander, 15 Plutonic rocks, texture and origi of, 142 River, feequenily , 42, bank f the, 423 —— ome on om biting jo tito, Volea ge, q i. Lug Of &$ con, Drinj. ovo, 07 ressidll ler’, 18 QD [3 o, #8 INDEX. 667 PO Po, delta of, Poisson on he oY evel by earth in passing i. ugh space, 302 Polar land, now Scag mal, 247 er a weit bs he covering, 644 I _ velopin - ee — pects preserved in, 6 45 — 647 — skeletons buried in, 648 Pont Giband, clears springs near, 400 Ponzi, Professor, on fossil mammoths of Monte Sacro, 186 Port Hudson Bluff, buried forest in, 462 Portland, fossil aa of, 42 — Isle of, wasting away, 5 35 4 — trav ea es cubmer red seboes s 544 rre y lav: ee action of, in ue ink “344, 346 Trade winds, 497 cen eee of ee bie Transition texture, Trap acs of many dirt ages, 117 Travertin of the Elsa — — San Vignone, io” — San bg ie “ — of Tivoli, sate pre 406 } oe Mr., on une deposits of Red Sea , 59 Tees geology of, 59 Tyndal on motion of glaciers, 373 Tyrol, earth-pillars of, 335 Siena: MABLE strata, inferences derived from, 316 Uniformity of Bilge changes, 805—309 Universal deposits, theory of, 112 — ocean, theory of, 40, 51 Upheaval, pr oofs of slow, 181 VW" Fines, excavation of, in Central Fi e, 356 — newly formed, 344 Vallisneri on natal causes of change, 54 ° wD oe i Venetz on recession Ly OF es before tenth century, 278 Ww Verneuil, ar de, cit oka t ‘Calas 114 . cae teik le ke uvian mi ae Yes anomie rae of, 602 newal “ eruptions of, 603 _ ee kes of, 6 -— price of, ‘afte er 1138, 606 — moder eae of, 618 ee f, 620 and Somma, ideal eiian of, 631 istula, River, its course diverted by packed ice, Voldante action defined, 577 — distri . of Naples, 59: — mud or ‘ moya’ of Andes, 583 — region ane Asia to Azores, 591 — regions, geographical boundaries of, 579— 597 — vents, linear arrangement of, 5 Poiana: a cause gens batons, 896 — and atolls, map ee ve, — howto disth inguish stv romextinet, of Phlegrsean Fields, — — Sandwich Island —— are rae 8, sconting t oo 25 Geo Von Baer, on ice- = sana ic ee Von Buch cited, 2 a fleaatat volenni rocks, 580 — — — form sag “ e Nuovo, 610 — — hypotl ation craters, 633 —_— on parce in — 380 — — rents in volcanos, 614 Von Hoff on lev an, Von Schrenck on as eee ee animals, 186 Vulcanists and Neptunists, 71 We , Mr., on wes lake of Trinidad, 414 Wallace, Mr. A., on former connection of fy Isla nds, a — on deposition of Nile mud, 437 W see theory 0 Wallich ,on ‘Aa fossils, 43 — — — wood in peat near po esiciaee: 478 ‘Warping, land gained Waste and repair of c ed . renidel on, 55 er of, 347 W ater poet action of running, 344— Webste r., on rain-prin Wells, Artesian. See Artesiax Is. Wener, Lake, horizontal Silurian strata of, 315 Werner, his lectures, 68—70 on transition te eisiy e of rocks, 141 Ww est Indies, active voleanos in, 584 — Upper spi strata of, 201 Ww hales, migrations of, to north a 286 Whewell on pes ical enquiry. 9 goivard, jooge on INDEX, 671 WHI n Sill, long volcanic dike, 578 oo the ie his deren 7 QE Tauston, his th ah of the earth, 48 4% Xenophanes on marine fossils, Whitehurst, theory of, 66 White Mountains, Tai in the, 38 Wilkinson, Sir J. G., on deposits of Nit 433 ab K, wild ox of Tibet, frozen in ice, 19 Williams, his opposition to Hutt ton + Yarmouth, estuary silted up at, 516 Wilson, ny, 6 Yorkshire, waste of coast, 509 Winds, currents caused by the, 499 Winter in aphelion, effects of, 271 ter, long and cold, in as hemi- ean. 243 Yaa ALAND, New. 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