PRESENT CHANGES IX THE EARTH. 



107 



which comes from the glacier of the Viesch is seen in 

 Fig. 4]. 



Fig. 41. 



190. Effects of Glaciers. Fragments of rock of vari- 

 ous sizes, from large stones to pebbles, and even sand, 

 become imbedded in the bottom and on the sides of the 

 glacier. These, held firmly in the ice, rub on the bottom 

 and sides of the valley, and when these are laid bare by 

 the melting of the glacier toward its termination, the 

 rocks exhibit varous marks, as grooves, striae, scratches, 

 roundings, smoothings, etc., according to the shape and 

 character of the fragments that have been brought in 

 contact with them under the immense pressure of the 

 glacier. Stones that are loose are crushed and ground 

 to sand, some even to mud. Fig. 42 (p. 108) shows the 

 side of a glacier valley after the melting of the glacier. 

 The rocks are striated, smoothed, and rounded wherever 

 the ice has been, while the portions which were above 

 its reach present the usual rough and ragged appearance 

 of hard rocks. 



All the crushed and ground matter is at length 



