20 SOILS 



striking testimony to their abrasive power. In a 

 surprisingly short time rough corners are worn 

 smooth, great boulders are undermined, hollows 

 are scoured out, and sometimes large, erect rocks 

 are completely filed off near the base, where the 

 wind-blown sand is thickest, and fall over. The 

 "Mushroom Rocks'* of Wyoming are a notable ex- 

 ample. In humid sections, the filing of rocks by 

 blown sand is less conspicuous, except near the 

 sea-coast. The windows of houses near the coast 

 are roughened and sometimes eaten through by the 

 natural sandblast. 



THE SOIL TEEMS WITH LIFE 



There are other soil builders, more minute but not 

 less active or influential than those that have been 

 mentioned. The old idea was that the soil is dead; 

 the fact is, it teems with life. It contains germs of 

 decay, bacteria that influence in some mysterious 

 way the palatability of plant foods, ferments of 

 many kinds, moulds of diverse sorts a fertile soil 

 fairly hums with activity. Countless tiny organ- 

 isms, visible only to the eye behind a micro- 

 scope, are constantly at work, changing, break- 

 ing down, building up. Some are beneficial, 

 some are harmful, some are harmless. How 

 many kinds there are, and what part each plays 

 in the complex operation of sou building, no- 

 body knows, for the science of bacteriology is yet 

 at its beginning. 



f Every farm presents many phases of soil building 

 and soil wasting. The farmer should observe the 

 various agencies at work upon his land, and turn 

 them to his own profit. He should remember that 

 the soil is not dead, but alive; that it is constantly 



