EXERCISE A-11. TO STUDY THE EFFECT OF FREEZING 

 AND THAWING UPON SOIL GRANULATION. 



Equipment: Shallow pans; some clay soil. 

 Method: Using heavy clay, make up two mud balls 

 to about the consistency of putty. Place one on a shelf 



Fig. 11. — ^Running Water, Freezing and Thawing, and the Roots of 

 Trees are Powerful Agencies in the Breaking Down of Rock to 

 Form Soil. 



to dry and the other outside on the window sill where 

 it will be frozen. Arrange to have the latter alternately 

 freeze and thaw each day for a week or longer. When 

 both are dry crush them with the hands. Which breaks 

 the more easily? 



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