It must be evident, that the objection to the Theory, here supposed to be made, is founded necessarily upon this, that the solid basis of our continent, on whose surface are found the lakes in question, is preserved without change, because, otherwise, the smallest variation in the basis may produce the most sensible effects upon the surface; and in this manner might be produced dry land where there had been a lake, or a lake where none had been before.  But, as the present Theory is founded upon no such principle of stability in the basis of our land, no objection, to the wasting operations of the surface of the earth, can be formed against our Theory, from the consideration of those lakes, when the immediate cause of them should not appear.

The natural tendency of the operations of water upon the surface of this earth is to form a system of rivers every where, and to fill up occasional lakes.  The system of rivers is executed by wearing and wasting away the surface of the earth; and this, it must be allowed, is perfect or complete, at least so far as consistent with another system, which would also appear to be in nature.  This is a system of lakes with which the rivers are properly connected.  Now, as there are more way than one by which a lake may be formed, consistent with the Theory, the particular explanation of every lake must be left to the natural history of the place, so far as this shall be found sufficient for the purpose.

There are many places which give certain appearances, from which it is concluded, by most intelligent observators, that there had formerly existed great lakes of fresh water, which had been drained by the discharge of those waters through conduits formed by some natural operation; and those naturalists seem to be disposed to attribute to some great convulsion, rather than to the slow operation of a rivulet, those changes which may be observed upon the surface of the earth.  Let us now examine some of those appearances, in order to connect them with that general system of moving water which we have been representing as every where modifying the surface of the earth on which we dwell.

It is the P. Chrysologue De Gy, who gives the following description.  Journal de Physique, Avril 1787.

“La principaute de Porrentrui l’emporte encore en ce genre sur le reste du Jura a ce qu’il paroit.  On pourra en juger sur les circonstances locales que je vais rapporter.  Une partie de cette principaute est divisee en quatre grandes vallees, d’environs quatre lieues de long, sur trois quarts-d’heure ou une heure de large, separees par autant de chaines de montagnes fort eleves et large en quelques endroits d’une lieue et demie.  Les extremites de chacune de ces vallees sont plus elevees que le milieu, et on ne peut pas en sortir par ces extremites sans beaucoup monter.  Mais ces vallees ont des communications entr’elles par une pente assez douce a travers ces masses enormes de montagnes qui les separent, et qui sont coupees