39. The uprisings of the Earth in one solid mass have necessarily displaced the waters which have flowed back into hollow places, become deeper by the uprising of emerged rocks and by depressions; but these same low depths have been raised in their turn sometimes in one place, sometimes in another, and have repelled the waters, which have flowed elsewhere successively until they have found a stable resting place.
The successive displacements of this liquid mass have violently agitated the surface of the Earth. The waters, in passing away, have drawn portions of rocks of anterior formation, brought to light by the earthquakes; denuded mountains which were recovered, and brought to light their granite or calcareous base. Deep valleys have been hollowed out, and others filled in.
There are, then, mountains formed directly by the action of the central fire: they are principally granite mountains. Others are due to the action of the waters, which, in drawing mellow Earth and soluble matters after them, have hollowed out valleys around a calcareous or other resisting base.
The substances drawn by running waters have formed the beds of the tertiary period, which are easily distinguished from the preceding ones less by their composition, which is nearly the same, than by their disposition.
The beds of the primary, transition, and secondary periods, formed upon a slightly undulating surface, are nearly uniform over all the Earth. Those of the tertiary period, to the contrary, formed upon a very unequal base and by the procession of the waters, have a more local character. Everywhere, by digging to a certain depth, one finds all the anterior beds in the order of their formation; whilst the tertiary rocks are not found everywhere, nor all the beds of the latter.