de nature schisteuse, tournent aussi le dos a la vallee en s’elevant contre le nord.  Je crois pouvoir conclure de la, que cette vallee est une de celles dont la formation tient a celle des montagnes memes, et non point a l’erosion des courans de la mer ou des rivieres.  Les vallees de ce genre, paroissent avoir ete formees par un affaissement partiel des couches des montagnes, qui ont consenti, dans la direction qu’ont actuellement ces vallees.”

Here I would beg leave to differ a little from this opinion of M. de Saussure, at least from the manner in which it is expressed; for perhaps at bottom our opinions upon this subject do not differ much.

M. de Saussure says that the formation of this valley depends upon the mountains themselves, and not upon the erosion of the rivers.  I agree with our author, so far as the mountains may have here determined the shape and situation of the valley; but, so far as this valley was hollowed out of the solid mass of our earth, there cannot be the least doubt that the proper agent was the running water of the rivers.  The question, therefore, comes to this, How far it is reasonable to conclude that this valley had been hollowed out of the solid mass.  Now, according to the present theory, where the strata consolidated at the bottom of the sea are supposed to be erected into the place of land, we cannot suppose any valley formed by another agent than the running water upon the surface, although the parts which are first to be washed away, and those which are to remain longest, must be determined by a concurrence of various circumstances, among which this converging declivity of the strata in the bordering mountains, doubtless, must be enumerated.

With regard to any other theory which shall better explain the present shape of the surface of the earth, by giving a cause for the changed position of the strata originally horizontal, I cannot form a judgment, as I do not understand by what means strata, which were formed horizontally, should have been afterwards inclined, unless it be that of a power acting under those strata, and first erecting them in relation to the solid globe on which they rested.

Besides, in supposing this valley original, and not formed by the erosion of the rivers, What effect should we ascribe to the transport of all those materials of the Alps, which it is demonstrable must have travelled through this valley?  Whether is it more reasonable to suppose, on the one hand, that the action and attrition of all the hard materials, running for millions of ages between those two mountains, had hollowed out that mass which originally intervened; or, on the other, that this valley had been originally formed in its present shape, while thousands of other valleys have been hollowed out of the solid mass?

But to put this question out of doubt, with regard to this very valley of the river Doire, M de Saussure has given us the following decisive fact, Sec. 881:  “Immediatement au-dessus de cette source, est un rocher qui repond si precisement a un autre rocher de la meme nature, situe de l’autre cote de la vallee de Courmayeur, qu’on ne sauroit douter qu’ils n’aient ete anciennement unis par une montagne intermediaire, detruite par les ravages du temps.”