ORIGIN OF THE SOIL 23 



surface; generation after generation of plants have grown 

 in the debris, and, dying, have left their remains to enrich 

 the deposit ; bacteria, the smallest of living things, have 

 here found a congenial home and have added their share to 



FIG. 9. A glaciated valley in southern New York 

 Note the irregular surface 



the cycle of changes ; thus have the ragged fragments of rock 

 that in the beginning were unable to support the growth of 

 plants been turned into the rich and fertile soil in which 

 are grown the luxuriant crops upon which the very life of 

 man depends. 



