318 liECTUEE XI. 



it seems to me that we are justified in assuming, that such, 

 blocks as rest upon the old alluvium have not been transported 

 directly by glaciers, but by floating ice blocks. If, indeed, the 

 glaciers had any influence upon the soil, as asserted by some 

 English authors, the influence must have been proportionate to 

 the acting mass. A glacier measuring several thousand feet in 

 thickness, which must be assumed to account for the blocks 

 found on the Jura, must have scooped the soil rather deep, 

 whilst an extremity of a glacier scarcely 100 feet thick, might, 

 for some short distance, pass over a gravelly soil without dig- 

 ging deeply into it. Charpentier, I beheve, cites such an in- 

 stance in WalUs, where, after the stay of the extremity of a 

 glacier for a number of years upon vegetable earth, immediately 

 after the retreat perennials appeared, as if the glacier had ex- 

 ercised no influence upon the soil. But it must be considered 

 that this can only apply to the extremity of a comparatively 

 very small and thin glacier. We may, therefore, assume that 

 in some spots during the retreat, not merely a stoppage but 

 sometimes an advance took place, during which the extremity 

 of a glacier passed a certain distance above the previously de- 

 posited old alluvium and also deposited blocks. But we can- 

 not believe that the glaciers spread again in this manner over a 

 great portion of Switzerland, as in this case they would from 

 their weight and size have necessarily scooped out all the older 

 drift and alluvial formations, and destroyed all the loose sand 

 and gravel masses. 



In East Switzerland we meet with various phenomena, con- 

 ditioned by the existence of buried forests and peat bogs. In 

 the vicinity of Utznach and Diirnten, on the lake of Zurich, and 

 near Morschwyl, on the lake of Constance, there are consider- 

 able beds of slate-coal, which manifestly belong to the period 

 we speak of, having originated from the peat bogs, which have 

 been overwhelmed and compressed by enormous masses of 

 drift. This peat bed consists mostly of mosses and reeds, 

 rushes and marsh-trefoil, upon which, at first pines, and then 

 firs and birches, grew. The disposition of these layers is as 

 follows : — 



The subsoil of the whole region is formed by molasse, the 



