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Some Minor Erodinc4 Agencies. By J. T. Scovell. 



The major or more effective erosive agents are : Heat and cold, air and water, 

 plants and animals, wind, flowing water and ice. 



The roots of growing vegetation sometimes open fissures in soils and rocks so 

 as to hasten erosion, but generally growing vegetation is conservative in is action, 

 serving to hinder the work of erosion. But decaying vegetation, especially trees, 

 often open the ground to the water, and frequently a gully has its beginning from 

 rain-water eutering the ground along the decomposing roots of some ancient forest 

 tree. 



Burrowing animals, as the ground hog and gopher, the badger and prairie- 

 dog, rabbits, mice and crayfish, bring loose soil to the surface, where it can be 

 scattered by the wind or washed away by the rain. Air and water, by means of 

 these openings, penetrate the ground with their disintegrating powers, and the 

 cause of erosion receives material aid. Again, the track of a mole breaks the 

 surface, and is the beginning of a drainage channel whose extent is limited only 

 by the amount of rainfall and the steepness of the slope. Smaller animals of 

 lower groups are also important erosive agents. 



Darwin mentions earth-worms, and calls attention to the immense amount of 

 work they do in working over the soil, rendering it more porous and fertile, and 

 opening it to the action of more active agents, as air and water. 



Burrowing spiders do a similar work ; they are not as numerous as the earth- 

 worms, but their burrows are wider and generally deeper than those of the earth- 

 worm, so that, with fewer numbers, they still do a great amount of erosive work. 

 They are abundant everywhere, in yards and fields, between the bricks of walks 

 and by the roadside. Frequently they build a little curb of sticks, bits of grass 

 or other material, so that the burrow somewhat resembles a well. 



Grasshoppers aid in erosion when they open the ground for their eggs. They 

 do not form a very large or a very deep hole, but when their great numbers are 

 considered, it soon appears that they are erosive agencies of no mean proportions. 



The male cricket in some localities does a work that is quite similar to that 

 of the garden mole, only on a smaller scale. An immense number of the cole- 

 aptera spend a large portion of their larval stage underground. The entrance to 

 their burrows and the opening for their escape stirs up the ground to the action 

 of air and rain. Thus these humble workers contribute their mite toward keep- 

 ing the land on the run toward the sea. The numerous family of burrowing 

 beetles and manv others as adult insects aid in this work. 



