and of the Alps of Savoy. 103 



a. Neocomian, whicli is characterised by the Holaster 

 complanatus, the Gryphees, and Crioceras. The last men- 

 tioned fossils have been found only in erratic blocks. 



b. First zone of the rudistes, or limestone with Hippurites 

 or Chama ammonia ; nummulites are never observed. This 

 bed is the one which has most influence on the relief of the 

 surface in the cretaceous districts of the Alps. It forms, in 

 general, dentated crests, very arid, and of great elevation. 



c. Albian formation, gaidt or green sandstones, very rich in 

 fossils, which, in certain localities, seems to alternate with 

 beds of limestone. 



d. M. Studer has described a formation, occurring in the 

 centre of Switzerland, under the name of Seeven limestone ; 

 but this formation does not exist either among the Western 

 Alps of Switzerland, or in those of Savoy. At Diablerets, 

 for example, we may place the hand in such a manner, that 

 one of its extremities rests on the green sandstone, and the 

 other on the nummulites limestone : it often even happens 

 that the fossils of these two beds are mingled. This obser- 

 vation, made in many other localities, is a good proof of the 

 non-existence of the Seeven limestone in these regions. 



All these stages of the cretaceous formation are confor- 

 mable with each other, but their stratification is not confor- 

 mable with the Jurassic formation. The latter, indeed, have 

 been subject to dislocations before the deposition of the cre- 

 taceous formation ; these dislocations are indicated by great 

 contoi'tions. 



These are seen in the bottom of some of those deep val- 

 leys, which permit us to obtain a view of the interior struc- 

 ture of mountains. These contortions, or rather this contor- 

 tion, for it is a single accident which we observe in different 

 localities, is placed on a line very nearly straight and paral- 

 lel with the Alps. I have observed it for a length of about 

 13 leagues : the most northern point is the Dent de Daily, 

 above the baths of Lavey (on the right bank of the Rhone). 

 These contorted beds pass below the great mass of the Dent 

 du Midi, and rc-appcar on the south-cast, under the glaciers 

 of Mont lluan, at the bottom of the Combe de Sixt. 



They arc likewise found in the lower part of the mountains 



