THE SOIL, HOW MADE, AND FROM WHAT 



19 



Figure 11 shows a view of a glacier. To understand 

 how ice may flow, we may support a long piece of ice, 

 or an icicle, at both ends (leaving the middle unsup- 

 ported), in freezing weather for several days. We 

 will see it sagging down in the middle, and finally take 

 the form of a U or a V. 



FIG. 11. A glacier or river of ice which is slowly flowing down from the 

 great mass of ice and snow at the back of the picture. 



Second, by weathering, by which is meant the action 

 of heat, cold, air, and water upon the rocks. Heat 

 expands and cold contracts rocks, as is the case with 

 everything else. Thus the action of heat and cold 

 makes crevices, at first minute, in the rock surface. 

 Water and dust enter these, and by freezing, and also 



