Thus, we may remark, that in Siberia, in those enor mous plains, well known by the descriptions of Pallas and other travellers, which are formed by the alluvia of powerful and variable rivers, the ordinary operations of time may have overwhelmed the dead remains, or inun dations of an extraordinary nature may have buried the living animals. Where these have been washed into lakes or into marine estuaries, it is easy to understand how they may have been buried, and how they must, in many cases, be found by digging in land thus rescued from the waters. In other and more obscure ones, they have been over whelmed suddenly by inundations or deluges of a more powerful and extensive nature ; matters which must be judged of by the disposition, the place, the depth, and the quality of these deposits, and by other collateral geolo gical appearances, from which the peculiar nature of these deluges is inferred. Thus, as we formerly attempted to to show, may the skeletons of the Isle of Man, among other instances, have been submerged beneath those deposits in which these remains are now found.
But it is time to quit this branch of the subject. The history of the species themselves, whether lost or survi ving, is the business of natural history in its other branches, and of zoology principally. We have already given, in the former part of this essay, as much respecting this subject as our limits would permit ; and, for those who are desirous to enter more largely on it, we can only recom mend them to the writings of envier and others, who have professedly treated on all these matters in great detail. To examine into the probable causes of the extinc tion of those animals that appear to be lost, into the history of skeletons of the Ohio and of Siberia, of the bears of Franconia, or the elephants and crocodiles of our own island, would be an interesting, as it is a circuitous, and, in a great measure, a speculative inquiry. But it rather belongs to zoology, and, under any point of view, would far exceed the space to which we must here confine ourselves. The changes of the climates, and of the vegetation of the globe in many places, the mutual collision and counteractions of animals themselves, and perhaps, most of all, the extending domination of man, the most predatory of the whole; these and numerous other inquiries, highly interesting as they are, must be sought among the writers to whose depart ments they properly belong, and who are not, like us, cramped by the consciousness that they are transgressing their proper boundaries.
On the Use of Fossil Remains in the identification of Strata.
It is now necessary to examine a question which is strictly geological; namely, the nature and value of the evidence which fossil remains afford towards the identifi cation of strata, whether in the same or in distant coun tries. Too much stress seems to have been lately laid on their utility in this respect ; a natural consequence of the enthusiasm which commonly attends the discovery of a new engine. It is in some degree connected with the
opinion which has been also held respecting the necessary identity of certain distant strata, and of an universal or very general deposition of particular rocks. The general question, as far as it is peculiarly of a geological nature, we dare not here enter on, as it would lead to a very long train of investigations; but we may state it, not only as our own conviction, but as now a prevailing opinion among all geologists, that no proof of such universal for mations, as they have been called, exist. The arguments which would prove that opinion, from a presumed identity between certain strata mutually and that of the fossils which contain, and which, of course, presume on a succession of fossil bodies as definite and cons4ant as the corresponding successions of the strata, are open to many other objections, which we must now proceed to ex amine.
Even admitting, that, in two parts of the globe, which we shall here suppose polar and equatorial, the same strata, as to the materials and constitution of the rocks themselves, should exist, and be found also in the same order, it is not to he expected that the same fossil bodies should occur in them, unless the differences of climate were considered an object of no moment. If in a weaker degree, yet the same objections hold good in those cases where the positions are far less discordant ; as even be tween the Mediterranean and the British Channel at pre sent, we do not find a correspondence in the living species. In every situation, were we even to consider the animals only, the sante reasons against such an identity among distant fossils in particular strata exist ; as we know that the different species inhabit different places irregularly, in colonies or otherwise, and that, even when mixed, they are limited to no determinate kinds or numbers. If to this we add the uncertainty of the strata themselves, the chances of a concurrence become so extremely small, as rather to make us wonder that such a notion could ever have been adopted. Many strata have been formed in independent cavities or seas, and are not likely to have corresponded in any respect; and at this moment one species, the oyster or the muscle, for example, is now an inhabitant of submarine alluvia of entirely different cha racters in different seas, or even in different parts of the same sea. There is no reason why the fossils of the Paris basin should be identical with those of the English ; because the living animals may have differed. If the bottom, again, of the English Channel should hereafter become an clevat ted stratum, the variety of its fossils would confound all this reasoning.