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bones of a deer (not distinguishable from a rein-deer, a species. now confined to frozen latitudes) with those of the Rhinoceros and other fossil quadrupeds of the same epoch.* They, however, belong to superficial gravel, and it is not pretended that the organic remains of this debris afford such strong indications of a tropical temperature as older formations; besides that it is impossible to affirm that animals thus confusedly mixed together were in every instance contemporaneous, or were not buried in the gravel at distinct and distant periods. That genera of animals now exclusively tropical may once have contained species adapted to live in colder climates is undeniable. We find existing species, for instance, of the Ox kind, universally distributed; the musk ox in the arctic, the common ox in the temperate, and the buffalo iu the equatorial regions. But notwithstanding these and other objections, the argument from analogy is unimpaired, so long as it is incontestably established that certain families or groups of genera of animals are at present characteristic of warmer climates, and are wanting, or but feebly represented, in colder latitudes: the same law holding equally with regard to assemblages of fossil remains, and most unequivocally so in some formations of considerable antiquity.

Although our knowledge of fossil Plants is more limited, they supply proofs, still more decided than do animal remains, of the ancient high temperature of the earth. The vegetation of tropical countries is now distinguished from that of colder latitudes by the luxuriance and predominance of the Palm tribe, by the arborescence of Ferns and certain kinds of Grasses, and many other characters; but several genera of plants are at present common to arctic, temperate, and equinoctial climates. Now, as we descend to ancient strata, particularly the coal, plants belonging to families and genera analogous to Palms, abound, together with Tree-ferns of great size, and Grasses arborescent on a scale of magnitude never obtained at present even between the tropics; while those genera and families now characteristic of cold climates, or even such as are common both to temperate and tropical regions, are entirely absent. The only approach yet discovered in the organization of any coal-fossils to plants now abounding in temperate climates is to be found in those supposed by some writers to have formed a link between the Palmaceous and Coniferous orders but even these latter, it will be remembered, are not excluded at present from tropical countries. Hence the most eminent botanists who have yet directed their attention to this study have been led to infer that, when the coal-plants were in existence, the heat

* Cuv. Discours sur les Rev. p. 342, 1825.

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solution; for we are not so warmly interested in favour of any theory, as to wish, with King Henry,

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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 uniform 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 sea. 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

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*On the Formation of Valleys by Elevation.' Geol. Trans. vol. ii. 2d ser.

p. 127.

force

force continued unimpaired even subsequently to the formation of some tertiary deposits, those geologists who contend it is now in the wane must reason from a very limited number of facts indeed.

Both Mr. Poulett Scrope* and Dr. Daubenyt in their recent publications agree in considering that the effects produced at present by earthquakes and volcanos are at least analogous in kind, if inferior in degree, to those that have resulted from similar agents at remote æras. More than 170 volcanos are at present in activity on the land, even if separate orifices at a short distance from one another be reckoned as one volcano; and there is reason to believe that there are at least as many, and probably a much greater number, beneath the sea-the power of which latter in throwing up islands and altering the bed of the sea is well known.

The chain of extinct volcanos described by the above mentioned authors in Auvergne, the latest of which became extinct before the period of any historical records; the streams of lava, which can be traced from their craters to the choked up vallies, and to the ancient courses of rivers thereby diverted into new channels ;these and many more phenomena raise the strongest presumption in favour of the great antiquity of some parts of the European continent. When we consider the deltas of large rivers, the strata at the bottom of freshwater lakes in Germany, Italy, and England, but, above all, the recent deposits at the bottom of the great American lakes Superior and Huron, inclosing shells of the very species now inhabiting those lakes and exposed to view in consequence of the subsidence of the water occasioned by the partial destruction of their barriers, we can affirm with certainty that modern freshwater deposits, of no inconsiderable thickness, far exceed in area the ancient freshwater formations, at present described. As to the scale on which submarine strata are now formed, we remain, of course, in comparative ignorance, but it is certainly more considerable than has been supposed by many. Whether the coral reefs of the East Indian archipelago are built up from an unfathomablé depth, as Flinders imagined, or are based on submarine volcanos, as Kotzebue and more modern writers suppose, we are at least certain, from the manner in which these zoophytes increase, and from the necessary accumulation of their broken fragments, that those aggregations of calcareous matter cannot be of slight depth, while we know that their superficial extent is immense. Captain King, in his late survey of Australia, sailed along a continued

* Considerations on Volcanos, by G. Poulett Scrope, Esq. London. 1825.

† See p. 2. Description of active and extinct Volcanos, by Charles Daubeny, M. D. London. 1826.

Letters to Professor Jameson, on the Volcanos of Auvergne, by Charles Daubeny, M. D. F. R. S.

§ Dr. Bigsby in the Journal of Science, &c. No. 37. pp. 262, 263.

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line of coral reef for 700 miles, interrupted only by a few intervals not exceeding 30 miles. These reefs stretch from the north-east coast of Australia towards New Guinea, and very far exceed in length any chain of secondary mountains in Europe. It is unnecessary to remind the geologist, how close a resemblance masses of such zoophytes intermixed with calcareous sand and the exuviæ of testacea so abundant in tropical seas, must bear to the greater part of the ancient oolitic formations. A calcareous concreted sand-rock unquestionably of modern formation has been found to exist in Australia throughout a space of no less than 25 degrees of latitude, and an equal extent of longitude, on the southern, west, and north-west coasts. We might adduce many more examples from the Mediterranean, and other seas, but we shall content ourselves with stating, in conclusion, that the stone of Guadaloupe containing the human skeletons is, in parts, as compact as the greater proportion of our secondary rocks. This description of rock is very common in the West Indian Archipelago, and increases rapidly; it forms the gained land,' which has extended the plain of Cayes in St. Domingo, and there the remains of pottery and other human implements have been found at the depth of 20 feet.*

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There are still, it may be said, some conglomerate rocks in Europe and in America, such, for instance, as are remarkably exhibited both in the old and new red sandstone formations, that evince a continued and destructive action over a great extent of the globe, unparalleled by existing causes. That the sudden elevation or subsidence of land might be attended with such ca, tastrophes will, however, hardly be denied. Earthquakes and volcanos are, for the most part, characterized by brief periods of intense activity, interrupted by irregular intervals of quiescence.+ Of the duration of these intervals we must be, at present, altogether ignorant, for centuries of complete tranquillity have intervened between recorded eruptions of volcanos accompanied with violent shocks of earthquakes.--But we cannot allow ourselves to speculate farther on these topics, and return to our zoological observations.

Of birds an extremely limited number have hitherto been discovered in a fossil state, and their scarcity forms a striking contrast to the abundance of other kinds of vertebrated animals. In the gypsum of Paris, however, before mentioned, several well defined species have been found and described by M. Cuvier. They were coeval with the Palæotherium and its contemporaries, and were different, like them, from any species now living; yet, with + Scrope, on Volcanos, p. 9. respect

Cuv. Discours sur les Rev. &c. p. 134.

respect to the general laws of co-existence and structure, and all that relates to the nature of their organs and their essential functions,' they were the same as those of our own time.'*

But in oviparous quadrupeds, remarkable alike for their magnitude and organization, nature has, in ancient epochs, teemed throughout these latitudes with a prolific power not exerted at present even between the tropics. These quadrupeds occur in strata of far more ancient date than the viviparous class. They make their first appearance in England in the lias, where many skeletons are procured in so perfect a state that the most exact knowledge has been obtained of their structure. In the volume before us are two excellent papers, by. Mr. Conybeare, on the osteological characters of the fossil genera Ichthyosaurus and Plesiosaurus, both first discovered and determined in this country. The Ichthyosaurus is an animal entirely sui generis; possessing, however, sufficient analogies with the Saurian order to justify our referring it to that great natural division:-it holds an intermediate place between the crocodile and lacertæ.'

Like the Cetacea it was exclusively an inhabitant of the sea; its eyes were of an enormous size, its neck short, its tail extremely long, its paddles broad and flat, and its whole frame admirably adapted for passing with rapidity through the water. Mr. Conybeare has ascertained four distinct species: one of these, I. communis, sometimes exceeds twenty feet in length; and I. platyodon was yet more gigantic.

The Plesiosaurus was still more extraordinary. Of this genus five species are ascertained. An almost entire skeleton of one of these-P. dolichodeirus, found in lias at Lyme Regis in Dorsetshire, and now in the possession of the Duke of Buckingham, is figured in this volume. This specimen does not exceed eight or nine feet in length, but the same species sometimes attained the length of twenty feet. It was distinguished from all known oviparous and viviparous quadrupeds, by a thin slender neck, equalling or exceeding the body in length, and composed of above thirty vertebræ.

'This great increase,' observes Mr. Conybeare,' of the number of joints in the neck is the more remarkable from the rigour with which nature appears in most cases to have enforced the law of a very limited number. In all quadrupedal animals, in all the mammalia, (excepting only the tridactyl sloths, which have nine,) the series is exactly seven; and so strict is this rule, that even the short and stiff neck of the whale, and the long and flexible neck of the cameleopard are formed out of the same elementary number; the vertebræ in the former instance being extremely thin and anchylosed together, and in the latter greatly elongated. Rep

* Cuv. Oss. Foss. vol. iii. pp. 15. 255.

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