There had therefore been also at least one change in the basin of that sea which preceded ours; it had also experienced at least one revolution.
He then gives proofs that such revolutions have been numerous.
"Thus the great catastrophes which have produced revolutions in the basins of the sea were preceded, accompanied, and followed by changes in the nature of the fluid and of the substances which it held in solution, and when the surface of the seas came to be divided by islands and projecting ridges, different changes took place in every separate basin." We now come to the Cuvierian doctrine _par excellence_, one in which he radically differs from Lamarck's views as to the genetic relations between the organisms of successive strata.
"Amid these changes of the general fluid it must have been almost impossible for the same kind of animals to continue to live, nor did they do so in fact.

Their species, and even their genera, change with the strata, and although the same species occasionally recur at small distances, it is generally the case that the shells of the ancient strata have forms peculiar to themselves; that they gradually disappear till they are not to be seen at all in the recent strata, still less in the existing seas, in which, indeed, we never discover their corresponding species, and where several even of their genera are not to be found; that, on the contrary, the shells of the recent strata resemble, as regards the genus, those which still exist in the sea, and that in the last formed and loosest of these strata there are some species which the eye of the most expert naturalists cannot distinguish from those which at present inhabit the ocean.
"In animal nature, therefore, there has been a succession of changes corresponding to those which have taken place in the chemical nature of the fluid; and when the sea last receded from our continent its inhabitants were not very different from those which it still continues to support." He then refers to successive irruptions and retreats of the sea, "the final result of which, however, has been a universal depression of the level of the sea." "These repeated irruptions and retreats of the sea have neither been slow nor gradual; most of the catastrophes which have occasioned them have been sudden." He then adds his proofs of the occurrence of revolutions before the existence of living beings.

Like Lamarck, Cuvier was a Wernerian, and in speaking of the older or primitive crystalline rocks which contain no vestige of fossils, he accepted the view of the German theorist in geology, that granites forming the axis of mountain chains were formed in a fluid.
We must give Cuvier the credit of fully appreciating the value of fossils as being what he calls "historical documents," also for appreciating the fact that there were a number of revolutions marking either the incoming or end of a geological period; but as he failed to perceive the unity of organization in organic beings, and their genetic relationship, as had been indicated by Lamarck and by Geoffroy St.Hilaire, so in geological history he did not grasp, as did Lamarck, the vast extent of geological time, and the general uninterrupted continuity of geological events.

He was analytic, thoroughly believing in the importance of confining himself to the discovery of facts, and, considering the multitude of fantastic hypotheses and suggestions of previous writers of the eighteenth century, this was sound, sensible, and thoroughly scientific.

But unfortunately he did not stop here.
Master of facts concerning the fossil mammals of the Paris Basin, he also--usually cautious and always a shrewd man of the world--fell into the error of writing his "theory of the world," and of going to the extreme length of imagining universal catastrophes where there are but local ones, a universal Noachian deluge when there was none, and of assuming that there were at successive periods thoroughgoing total and sudden extinctions of life, and as sudden recreations.