158 ON THE HEVOLUTIONS 



assisted by fractures, and by the sliding of the ice upon the 

 ground. In this manner the glaciers are produced, which con- 

 sist of an assemblage of great blocks of ice, each as big as a 

 house, which, sliding and rolling upon each other during sum- 

 mer, make their way from the high frozen valleys where they 

 were formed, through narrow glens, into the rich and wann 

 vales below, in which they remain a considerable time, pre- 

 senting a curious spectacle among the meadows and woods, 

 some of which they overtop. These masses, however, melt at 

 last, in this new situation, and leave vast assemblages of stones, 

 which had been attached to them, forming a ridge called the 

 Marene of the Glacier. 



It is obvious, then, that a wave washing over these high al- 

 pine valleys in summer, would float and carry oft" all the ice in 

 the glaciers, and accumulated in the higher valleys, and, along 

 with the ice, all the blocks of stone imbedded in it, or attach- 

 ed to it in any way. The stream, with this load, would find its 

 way through everj' opening, and would in a particular manner 

 flow through those depressions, which at this day, as we have 

 said, afford a view of the snowy summit of JMont Blanc, 

 from certain places on the face of Jura where these blocks 

 abound. 



The enormous masses already mentioned, which are found 

 near Geneva, and at the Coteau de Boisy, may now be ac- 

 counted for ; and the same system will apply also to the blocks 

 upon the Baltic, which may have been brought to their pre- 

 sent place, not by a permanent and steady position of the 

 ocean, varying by slow degrees, as has been alleged by M. 

 Wrede, but by a sudden diluvian wave washing over some di- 

 strict, situated either at a sufficiently high level, or near enough 

 to the pole to be the seat of glaciers. I am not at present ac- 

 quainted with any facts by which the native place of these 



blocks 



