330 GENERAL SCIENCE 



rainfall. In places like western Kansas, where strong 

 winds are usually blowing, much soil is moved by the 

 winds just after the farmers have plowed their fields. 

 Sometimes the soil particles and sand are flying in the 

 wind in such quantity that clouds of dust can be seen 

 from great distances. Along some of our seashores and 

 lake shores, small hills of sand are made by the wind. 

 These sandhills, called dunes, do not stay in one place, 



EROSION IN A NEGLECTED FIELD 

 On a very gentle slope. 



but move slowly in the direction of the prevailing winds. 

 The sand is picked up on the windward side of the dune 

 and then falls on the leeward side where the wind is less 

 strong. On the shores of Lake Michigan these sand 

 dunes move slowly eastward and sometimes bury valu- 

 able farm lands or even forest trees. The farmers try 

 to prevent the movement of the dunes by planting shrub- 

 bery and making fences on the windward side so that 

 the wind cannot pick up the sand and carry it to the 

 opposite side. 



In most parts of the United States the erosion caused 



