washed off the hills and lesser slopes into the streams, or con- 

 centrated in valley bottoms, and would be of limited use to 

 Man. This washing away of soils, known as "erosion", is 

 today one -of our most serious problems; a problem not 

 found in areas untouched by Man. Normal erosion is a 

 very slow cosmic form a carving which wears down rock 

 masses and creates soils. There is also a normal creeping of 

 soil masses. But natural forces hold to a minimum, unless 

 it is accelerated by Man's influence, that erosion which con- 

 sists of wide-spread washing away of soils already made. 



3. SOME INTERESTING ASPECTS JF BALANCE 



WE HAVE given principal attention only to the major aspects 

 of balance between water and land, and among the several 

 forms of water. However, within the frame of these major 

 balances, there are a large number of balances in detail. It 

 will be of interest to note a few of them briefly. 



A natural balance of retarded surface flow, underground 

 storage, and seepage from the latter, tends to maintain a 

 fairly regular supply of water in ponds and lakes, and of 

 flow in streams. With this regularity there develops also a 

 balance between water and organic life which provides food 

 for fish and wild fowl, and through these for Man. 



Ducks, geese, and other wild fowl thrive on the aquatic 

 plants and other organisms that grow in the water along the 

 shores of ponds, lakes, and streams, and in swamps, marshes, 

 and other wet lands. These fowl tend to disappear when 

 water bodies dry up or become irregular in level or flow, 

 because that balance of relations between water and land 

 along the shore line is upset and conditions become un- 

 favorable to propagation of the organic life on which wild 

 fowl feed. 



Fish, a more universal and important food for Man, 

 subsist upon larvae and micro-organic life, which subsist 

 upon decaying vegetation, which in turn is present only when 

 there exists a proper balance of water and soil relations for 

 its growth. Fish tend to disappear from bodies of water 

 that have great irregularity of level or flow, or are polluted 



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