116 Cliarpeiitier's Eafiatj 07i Glaciers. 



tains of that valley and of those which open into it. It is the 

 same with the moraines and beds of glaciers, which contain all 

 tlie rocks belonging to the mountains which encompass them. 



The form of the fragments, and the state of preservation of 

 the blocks, are the same in the one case as in the other. The 

 well preserved blocks are generally the largest, because roll- 

 ing to a greater distance at the moment of their fall, they 

 reached the back of the glacier and remained there during the 

 whole time of its progress. 



There are no blocks of too large a size for the expansive power 

 of the ice, and M. de Charpentier mentions a block of serpen- 

 tine in the valley of Saas of 244,000 cubic feet, which has 

 been transported for about a hundred years, by the present 

 glacier of Matmarck. 



The three forms of deposit In the erratic formation, scat- 

 tered, accumulated, and stratified, answer to the debris of the 

 beds of glaciers, to moraines, and to the alluvium glaciare. 



The want of selection in the blocks and groups of the same 

 species of rocks, the singularly balanced position which a cer- 

 tain number of them present, are explained in the most satis- 

 factory manner by the hypothesis of glaciers, those of our own 

 day exhibiting the same phenomena. 



The comparatively larger quantity of blocks disposed on the 

 flanks of the Jura than in the plain, is explained by this, that 

 lower Switzerland, which served as a bed to the glacier, had 

 no moraines formed in it ; the debris which it supported be- 

 came scattered at the moment of its destruction, and the free 

 lateral expansion to the right or left did not admit of aceu- 

 rnulations of debris on the flanks of the glacier. But it was 

 not thus with the flank of the Jura, upon which the great gla- 

 cier of the Rhone rested ; there the blocks accumulated and 

 iovxix^^'^i great frontal 7noraineyN\\\Q\\ is disposed on the declivity 

 of the chain of mountains which formed a limit to the glacier. 



The most elevated debris of the erratic formation are the 

 lateral moraines deposited at the moment when the diluvial 

 glaciers had acquired their greatest extent and thickness. 

 The elevation of these debris indicates this maximum. Thus, 

 in the upper Valais, from Aernen as far as Briguo, the glacier 

 nuist have been 2800 feet thick. At Brigue the valley 



