But the elevation of these above the level of the sea to their present positions, implies a fresh revolution of the surface; namely, that change which brought these strata, and the substance which they contain, within the reach of our examinations. \Ve may here again ask, whether that revolution destroyed the inhabitants of the globe, and whether the present creation is a distinct one. On this point also we have no valid evidence to offer. We are not absolutely certain that this revolution was universal, although that is rendered probable by the extensive distri bution of the red marl stratum, which exists, in fact, all over the world. Even then the same doubts remain as to the probable effects of such a revolution on the inhabitants of the globe as in the first cases; and, however much we may have reason to think that all terrestrial beings were destroyed, we must, as in those cases, remain in doubt whether that destruction extended to marine animals also.
Thus we arrive at a new order of things, which begins to associate itself with the present state of the earth as to its geological distribution and appearance; and, what is here more important, as to the races of beings by which it is now inhabited. Reviewing what is past, we see that the present position of fossil remains are not the con sequence of one retreat of the sea, or, more properly speaking, of one elevation of the land, hut of succes sive changes, of which we now see only the final result, in the present distribution of the sea and land, and in the various geological phenomena which have been described. If in some cases these have been partial, in others they have probably been general ; if gradual in some instances, in others they appear to have been sudden catastrophes. Thus also, in some cases, as in that of the coal strata in particular, the sea and the dry land have alternated. That which was once dry, supporting plants at least, if not animals, was submerged at a prior period, as it has again been submerged at a posterior one, to the loss and inter ment of its productions; suffering marine strata to be de posited upon it, again to be lifted into the light of day, and to afford a habitation for new races. Whether, in these revolutions and catastrophes the creation perished, whether tribes alone disappeared, whether particular spe cies or genera were destroyed, or have worn out, whether races entirely new have been created, or whether creation in general has been repeated and renewed, or only pro gressive and variable, are questions on which, however interesting they are, we can reason to no purpose from evidence merely physical, from those circumstances alone to which investigations of this nature are necessarily li mited.
Even on the present surface, we now trace some marks of revolutions connected with the history of fossil remains, and which, in sonic measure, unite the present with the last state of the globe ; forming a gradation, which is, however, apparently partial. Hence it is, that, in the more recent strata which lie above the chalk, we begin to be certain, by positive proofs, of the identity, to a considera ble extent, at least, between petrified or preserved fossils and living animals. Here then, we arc sure, not only from this, but from other geological evidence, that these re volutions have been partial. Thus, they may have destroy ed species or genera where they exterminated individuals, because these might have been limited to the spots in question, as many living animals are similarly situated at present.
Passing from these last revolutions, that include the subject lately described which relates to the alternating fresh-water and marine formations, we arrive at that state of the earth, which, geologically speaking, must be con sidered present; although, as relates to its inhabitants, it still exhibits marks of important changes, in the extinction of numerous genera and species ; possibly, in the creation of the most important of all. That man has never yet been found in the alluvial soil, is certain. Greater accu racy and knowledge have proved that all the fossil bones, once supposed to belong to him, were those of other ani mals, as we have mentioned at the commencement of this article; and the celebrated skeletons of Guadaloupe we have already shown to be imbedded in a very recent calca reous alluvial rock. Many existing animals have, however, been found thus imbedded ; nor is there any difficulty in explaining these appearances, when we recollect the man ner in which alluvial soils are deposited, whether gradu ally on plains, in the beds of lakes, in the estuaries of the sea, or under waters that have afterwards been laid dry, or, lastly, on land that has been elevated by the power of earthquakes or volcanoes. Many other animals thus found have disappeared from the particular situations where their remains exist ; others appear to have vanished from the world in general. In all these cases, the geological considerations implied are similar or identical, and require no further notice or illustration ; excepting where peculiar and accidental circumstances in the condition of the dif ferent alluvia render such instances remarkable. But such questions rather belong to the history of the compli cated alluvial deposits formerly mentioned.