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periods and at different intervals of time to destroy the animate productions of nature, modern industry has afforded ample proof; but the labours of geologists have also shown how much of the history of extinct races may yet be rescued from oblivion. It is now twenty years since Playfair observed, that the land has been raised by expansive forces acting from below, and there is reason to think, that continents have alternately ascended, and descended, within a period comparatively of no great extent.' When the Huttonians first advanced these doctrines, no geologists disputed that there existed proofs of former changes, in the relative level of land and sea, but Playfair's hypothesis appeared extravagant to many, and those were deemed ' fearless of paradox who,' as Mr. Greenough expressed it,* • attributed to the waves constancy, mobility to the land. Yet the Huttonians were conducted to these conclusions by the observation of a class of phenomena altogether distinct from what may now be considered as furnishing the most decisive evidence in favour of them. Playfair had examined with attention the dislocations and disturbances of rocks, but the alternation of a great series of marine and freshwater formations was not then established,—nay, has only been generally admitted since all the facts from which it is inferred have been rigorously examined by persons possessing a competent knowledge of organic remains, and who have compared recent with ancient freshwater deposits.
It may not be superfluous to mention a few of the most striking of these facts. The strata associated with the Coal contain in many countries indications of a fresh-water origin; and the vegetable remains preserved in them prove the existence of dry land at the period of their deposition. The bituminous copper slate of Thuringia is of an older date than the magnesian limestone of the English series; it contains reptiles of the Saurian family, closely resembling the great monster that now lives in fresh water in the torrid zone, and the unknown fish that abound in the same slate are regarded by Cuvier as related to freshwater genera. Strata of freshwater origin, and of considerable thickness, exist between the chalk and the oolitic series in the south-eastern districts of England. The chalk is exclusively a marine deposit; atd, from its great extent in Europe, and the absence of vegetable matter, sand and transported materials, is considered to have been formed at the bottom of a deep and tranquil sea. But above the chalk, both in this island and on the continent, alternations of marine and freshwater strata occur. The lowest of these are
* A Crit. Exam. of the First Principles of Geology, 191. + Cuv. sur les Rev. p. 299.
See Mem. by Dr. Fitton, Ann. of Phil. Nov. 1814.
only of different genera, but of three distinct classes of former systems, all united and blended together in one single individual,
To enter at large into the consideration of other classes of organic remains, or to examine in detail those described in the present volume, would be inconsistent with our present limits and scope. In the illustration of these objects, lithography has been success. fully employed. This art, so strongly recommended by its surior cheapness, may exert a favourable influence on the future progress of science, and particularly on natural history, which has always been retarded by the unavoidable expense of engraving. The plates descriptive of the osteological structure of the large Reptiles we have been mentioning deserve especial commendation, as do the figures of plants discovered by Mr. Mantell in the same strata with the Iguanodon, near Cuckfield in Susses. These remains consist partly of ferns, that numerous fossil genus, and partly of vegetables analogous to the genera Zamia and Cycas, now particularly characteristic of tropical regions. The plates of Orthoceræ* from the islands of Lake Huron are also admirably executed in lithography. These chambered univalve shells, so interesting to the conchologist from the peculiar structure of the siphuncle, are described in a paper by Dr. Bigsby on the geology of part of North America bordering on Lake Huron. No recent species of Orthocera hitherto discovered exceeds half an inch in length; the fossil species both in Europe and America frequently attain the length of many feet. The only multilocular univalve Testacea of large dimensicus now existing are some species of Nautilus, and these are confined to tropical climates. The abundance therefore of Ammonites, Orthoceræ, and Nautili of great magnitude, in the strata of Europe and North America, is worthy of observation, as tending, in concurrence with other branches of organic remains, to confirm that striking deduction of geology, that the former temperature of the northern hemisphere was much higher than it is at present.
As the fossil species appear to be all, with very few exceptions, extinct, we reason only from analogy when we draw this conclusion, and we ought therefore to require a great accumulation of evidence, together with perfect harmony in the proofs. This question, concerning the former temperature of the globe, is extremely interesting, and it has so often heen alluded to during our consideration of fossil animals and plants, that we shall lay before
* However great may be the expedience of a speedy reform in the nomenclature of
we must not attempt it in this place. It may be as well, in compassion to the uninitiatest, to inform them that, when Lamaick writes Orthocera, he means Orthoceras, and that, in the language now spoken by conchologists, Orthuceræ stands for
miles from the shore; the supposed area over which the earth-
Nearly at the same period, when these stupendous events were occurring in South America, Dr. Jack was, by a singular coincidence, composing his paper (which also appears in the present volume) on the geology of Pulo Nias, near Sumatra, to which island the author accompanied the late amiable and lamented Sir Stamford Raffles.
• Near the surface on all the hills,' he observes, f masses of coral origin are found lying immeiliately above the rocky strata, and, to all appearances, precisely in their original position, in general so little altered, that their different species can be determined with certainty.' These species are described as obviously the same with those which now abound in the neighbouring sea, such as the madrepora muricata, and other branched kinds, and sometimes,' he continues,' the transition from the recent to the fossil coral, is only effected by the gradual rise of the land from the shore. Large kima shells (chama gigas) are also found on the hills, exactly as they occur in the present reefs, and are collected by the inhabitants for the purpose of cutting into rings for the arms and wrists. Every thing seems to indicate that the surface of the island must at are time have been the bed of the ocean.' I From the great inclination of the strata of Pulo Nias, and the dislocation they sometimes appear to have suffered, and from the absence of similar unchanged and unfossilized corals and shells on the adjacent coast of Sumatra, Dr. Jack inclines to the hypothesis that there has been a heaving up of the island by a force from beneath;—Nay,
although it must be regarded,' he alds, as a phenomenon of a most singular kind, that so large an island, diversified with numerous hills from 800 to 3,000 feet in height, should have been heaved up from the sea with so little disturbance to the fragile marine productions on the surface,-the appearance and nature of these productions would indicate a comparatively recent date to the event.'s
In a paper by Mr. Strang ways on the geology of Russia, (also included in the volume now under review,) are some very important observations on the great changes in the distribution of land and sea that seem to have occurred at no distant period in one of those few portions of the globe of which we have any an
* Jour. Roy. Inst. for 1824. vol. xvii. pp. 10. 45. † Page 403.
† Page 404.
cient geographical information. He describes the steppe extend ing between the Black Sea and the Caspian as * lying at an extremely low and generally uniform level: it is marked (he proceeds) by an extreme want of fresh water, and is covered with sand and recent shells, such as are now found in the neighbouring seas.
The lakes and pools which it contains are mostly salt, and the scanty vegetation of the steppe consists of such plants only as are found with us on the sea coast, or which are of a like nature. The rock under the superficial sand is a hard clay, sometimes left bare.'* Mr. Strangways has traced on the map accompanying his memoir the supposed former communication of the Black Sea with the Caspian, and of the latter with the salt lake, Aral,
according to which there must formerly have been citlier two inland seas separated by land in the neighbourhool of the Bosphorus, or the Mediterranean must have extended to the interior of Asia as far as the low steppe continues; and in that case its eastern shore would bave been the high land which, in the steppe of the Kirgbis, connects the Altay with the Himalaya mountains. Many considerable islands and peninsulas would have been thus formed; such as the Crimea, Kharizm, the Beshtan, &c., for the bed of a strait is said to be traced across the isthmus of Perecop, including the steppe of the Dnieper on the north, and a part of that of the Crimea on the south; the lake Aral would bave been joined by narrow seas with the Caspian on the north-west, and perhaps also on the south-west, &c.' We must be satisfied with referring our readers to the author's own remarks on the illustration of several ancient geographical accounts and traditions afforded by these geological facts.
No one can reflect on the above statements without being tempted to inquire whether the causes now in action are, as Dr. Buckland has supposed, the last expiring efforts of those mighty disturbing forces which once operated ;'t or whether, as Hutton thought, they would still be sufficient in a long succession of ages to reproduce analogous results. The opinion repeated by M. Cuvier in his last publication, that it is in vain to search in the forces now acting on the surface of the earth for causes sufficient to produce revolutions and catastrophes of which the traces are exhibited in its envelope,' is entitled without doubt to the more respect, as it seems to have been adopted by many in these later times, when additional facts have been so industriously accumulated. The total amount of change that has fallen under the observation of mankind in the course of 3,000 years is, however, so small, that the final decision of this question may certainly be regarded as incalculably remote, and indeed we can be content, for our part, to waive the speedier * Page 37.
+ Vindicia Geologicze, p. 5.
solution ; for we are not so warmly interested in favour of any theory, as to wish, with King Henry,
that one might read the book of fate
Into the sea.' But in the present state of our knowledge, it appears premature to assume that existing agents could not, in the lapse of ages, produce such effects as fall principally under the examination of the geologist. It is an assumption, moreover, directly calculated to repress the ardour of inquiry, by destroying all hope of interpreting what is obscure in the past by an accurate investigation of the present phenomena of nature.
Those naturalists who have prosecuted with the greatest success the study of fossil remains concur in opinion that the earth during the deposition of the secondary strata was not in a state of chaotic confusion. There are proofs of occasional convulsions, but there are also proofs of intervening periods of order and tranquillity. The notion of a continually decreasing energy in nature's power to modify and disturb the earth's surface first originated in the observation that strata of the highest antiquity have suffered the greatest and most general derangement. But such must be the necessary effect of the uniforin action of the same cause throughout a long succession of ages; and the frequent unconformability of strata clearly shows that disturbances have taken place at many and at different periods. There would perhaps have been some weight in the argument if the derangement of recent deposits were not merely of more partial occurrence, but invariably on a scale of inferior violence. But the fact is far otherwise. We find the chalk in Ireland extensively intermixed with trap, and in Hampshire thrown together with more recent formations into a vertical position. Beds of the purbeck series in Dorsetshire, and of the plastic clay in the Isle of Wight, are contorted in the same manner as primary clay slate. In no part of Europe are effects of disturbance displayed on so stupendous a scale as in the Alps. Yet the date of this convulsion is, geologically speaking, extremely modern, for marine strata as recent as the green sand, chalk, and even some tertiary formations are discovered in this chain at an elevation of more than ten thousand feet above the level of the Professor Buckland has remarked that these Alpine tertiary deposits are contemporaneous fragments of the more extensive strata of the adjacent low countries.* Since then the disturbing
* • On the Formation of Valleys by Elevation.' Geol. Trans. vol. ii. 2d ser. p. 127.