During a long time, two events or epochs only, the Creation and the Deluge, were admitted as comprehending the changes which have been operated upon the globe; and all the efforts of geologists were directed to account for the present existing state of things, by imagining a certain original state, afterwards modified by the deluge, of which also, as to its causes, its operations, and its effects, each entertained his own theory.
Thus, according to one[15], the earth was at first invested with an uniform light crust, which covered the abyss of the sea; and which being broken up for the production of the deluge, formed the mountains by its fragments. According to another[16], the deluge was occasioned by a momentary suspension of cohesion among the particles of mineral bodies; the whole mass of the globe was dissolved, and the paste thus formed became penetrated with shells. According to a third[17], God raised up the mountains for the purpose of allowing the waters, which had produced the deluge, to run off; and selected those places in which there was the greatest quantity of rocks, without which the mountains could not have supported themselves. A fourth[18] created the earth from the atmosphere of one comet, and deluged it by the tail of another: The heat which it retained from its origin, was what, in his opinion, excited the whole of the living beings upon it to sin; for which they were all drowned, excepting the fishes, whose passions were apparently less vehement.
It is evident, that, even while confined within the limits prescribed by the Book of Genesis, naturalists might still have a pretty wide range: they soon found themselves, however, in too narrow bounds; and when they had succeeded in converting the six days of creation into so many indefinite periods, the lapse of ages no longer forming an obstacle to their views, their systems took a flight proportioned to the periods which they could then dispose of at pleasure.
Even the great Leibnitz amused himself, like Descartes, by conceiving the earth to be an extinguished sun[19], a vitrified globe, upon which the vapours falling down again, after it had cooled, formed seas, which afterwards deposited the limestone formations.
By Demaillet the whole globe was conceived to have been covered with water for many thousands of years. He supposed this water had gradually retired; that all the land animals were originally inhabitants of the sea; that man himself commenced his career as a fish; and he asserts, that it is not uncommon, even now, to meet with fishes in the ocean, which are still only half converted into men, but whose descendants will in time become perfect human beings[20].
The system of Buffon is merely an extension of that of Leibnitz, with the addition only of a comet, which, by a violent blow, struck off from the sun the liquefied mass of the earth, together with those of all the other planets at the same instant. From this supposition, he was enabled to assume positive dates, as, from the present temperature of the earth, it could be calculated how long it had taken to cool down so far; and, as all the other planets had come from the sun at the same time, it could also be calculated how many ages are still required for cooling the greater ones, and to what degree the smaller are already frozen[21].