78 M. Ch. Martins 07i the 



the Ai've, (vnd not one on the right I From Servoz as far as 

 St Martin, in front of Sallenches, we may believe that these 

 blocka are buried in the eboulements of the mountain of Fis, 

 and the Aiguille of Varens ; but above the cascade of Nant 

 d'Arpenaz and the village of Maglan, the mountain presents 

 uncovered terraces. M. Rendu has already solved this diffi- 

 culty. He observes, that, at the height of Servoz, a power- 

 ful glacier coming from Buet, must have debouched on that 

 of the Arve, by the Col d'Anterne. This considerable afflu- 

 ent, moving in a parallel direction to the glacier of the Arve, 

 and forming its right side, carried along v/ith it no blocks of 

 protogine ; its moraine was calcareous, like the mountains 

 which overlook it. Now, the buttresses of the valley of 

 Maglan being of the same nature, this moraine is con^ 

 founded with the rocks that have fallen from the mountains. 

 Nothing, in fact, is more difficult than to distinguish erratic 

 blocks, when they have the same aspect, and are of the same 

 mineralogical composition, as the rock on which they rest. 

 On the other hand, these fragments of limestone, slate, and 

 sandstone, have not resisted the influence of atmospheric 

 agents like protogine, and have been in a great measure de- 

 stroyed. 



We perceive, that the theory of the ancient extension of 

 glaciers explain very well the separation of the blocks of pro- 

 togine, and of the calcareous moraine. The supposition of a 

 diluvian is inadequate to resolve this difficulty. How, indeed, 

 can we comprehend how an impetuous torrent, which would 

 have carried along with it in confusion fragments of limestone 

 and blocks of granite, would have deposited the one on its 

 left bank, and the other on its right, without ever mingling 

 them with each other ? This supposition is inadmissible, and 

 proves the insufficiency of the diluvian hypothesis. 



The long lateral moraine which extends from Cluzes to 

 Bonneville forms an uninterrupted zone along the whole 

 right side of the valley. The last blocks of this moraine are 

 often 640 metres above the Arve ; witness those observed in 

 the neighbourhood of the church of Mont Saxonex, whose 

 elevated position and picturesque appearance attracts the 

 eyes of the traveller from afar. The whole plain comprised 



