SURFACE OF THE EARTH 199 



roots are embedded in it. Many animals also live in the soil, 

 and all of them are dependent directly or indirectly upon the 

 plants that grow within or upon the soil. Animals burrow 

 in the soil, as the earthworm, the gopher, the fox, and the 

 hedgehog, and thereby secure food in the form of plant roots 

 or decaying organic matter, or secure homes that furnish 

 them a measure of protection from enemies or from extremes 

 of temperature. 



All must have noted the fact that the soils of different 

 regions may vary widely, as well as the plants and animals 

 that live upon or within the soil. What are the differences 

 of these various soils, and what are the common elements in 

 them? 



