changed the Surface of Switzerland. 29 



sion, was much shallower in the north and west of the canton 

 than towards the south and east, or in the direction of the 

 Alps. This conjecture is founded on the fact, that the rocks of 

 the Jura contain infinitely more species and individuals of ma- 

 rine testacea than the same rocks in the Alps ; and it is well 

 known that molluscous animals diminish in number in propor- 

 tion to their distance from the shores and shallows, and to the 

 increased depth of the sea. The northern and western shal- 

 low, of which we are now treating, is a limestone, generally of 

 a light yellow, disposed in beds, and contains a prodigious 

 quantity of marine remains. 



It was also, in its turn, raised and pushed up above the sur- 

 face of the water. This immense mass of formation, break- 

 ing up into long stripes, formed those chains of mountains pa- 

 rallel to each other, of which the whole goes under the name 

 of Jura. * 



But this country was by no means elevated all at once to 

 the absolute height at which we now find it above the ocean. 

 The sea still washed the bases of those new mountains ; it 

 even entered into several of their valleys, and deposited in 

 them rocks of a new order, known under the name of the chalk 

 formation. 



At some distance to the south, and shortly before the souleve- 

 ment of the Jura, or more probably at the same epoch, a 

 pretty considerable formation likewise appeared above the wa- 

 ters. It comprehends the chains of mountains of the Mont Ar- 

 vel (above Roche), of Naye, the Verraux, and the Moleson. 

 We are entitled to suppose that those two soulevemens are 

 contemporaneous; because the rocks proper to the chalk forma- 

 tion, the deposition of which followed immediately after the 

 soulevement of the Jura, are not met with on the mountains 

 which we have named, and which were therefore above the wa- 

 ters at the period of that formation. 



To this great convulsion there succeeded an interval of repose, 

 duringwhich the shores of the sea, and the dry land, were peopled 

 by a certain number of amphibious animals, of different shapes, 

 some of which were gigantic and of singular forms. An infinite 



" According to the researches of M. Elie de Beaumont, the Cote* d'Or in 

 Burgundy, and Mount Pilas in Forez, were raised at the same epoch. 



