290 THE EARTH'S SURFACE AND PLANT LIFE 



among the higher mountains in the western United States, 

 and in fact wherever the snow accumulates in the mountain 



valleys year after 

 year. 



As glaciers creep 

 down the valleys, 

 dirt and rocks fall 

 upon their edges 

 from the upper val- 

 ley sides and are 

 borne along upon 

 the ice. If two 

 glaciers unite to form 

 a larger one, the 

 debris upon the two 

 sides which come 

 together forms a 

 layer of dirt and 

 rocks along the 

 middle of the larger 

 glacier. At the end 

 of the glacier this 

 material which it has 

 borne along is de- 

 posited in irregular 

 piles of rock and 

 dirt. 



The accumulations 



of debris along the sides are called lateral moraines, those 

 in the middle, medial moraines, and those at the end, 

 terminal moraines. Great bowlders may be carried along 

 on the ice for long distances without the edges being 



THE FIESCH GLACIER 



A winding " river" of ice, bearing a medial 

 moraine. 



