190 BOULDEB REVERIES. 



many tracks, but not those of animals. They 

 are the traces of hundreds of pellets of clay and 

 gravel which, in this moist thawing air, have 

 rolled down over the newly fallen snow onto the 

 ice. Thousands of years ago the clay in those 

 pellets was piled up and deposited in a solid 

 bed by the melting of another ice sheet of 

 enormous thickness which then covered all this 

 area. There it has lain until the frost again 

 acted upon it, setting it free from the bed or 

 face of cliff where it has been held for centuries, 

 and allowing gravity to pull it down upon an- 

 other but far thinner bed of ice. When this 

 breaks up the pellets will be carried down 

 stream, some on ice cakes, others in water, until 

 they are again deposited as the alluvial soil of 

 some field. There the elements now locked up 

 in their midst will become a part of grass or 

 grain, and then of some animal which will give 

 them wider distribution. 



As I stand in front of the clayey cliff and 

 write these words the particles are incessantly 

 rolling and sliding down. They well illustrate 

 in miniature the action of frost on the sides of 



