32 



BULLETIN 615. U. S. DEPARTMENT OF AGRICULTURE. 



systems ran usually be effectively broken up by the construction of 

 terraces laid out approximately at right angles to the gullies but so 

 placed as to allow water to be carried through their channels. If 

 reinforced- by small rock fills built into the washes at sufficiently 

 frequent intervals to check the run-oil' before the cumulative effect 

 of the water's force becomes uncontrollable, the terraces appear to 

 be effective. 



Fig. 7. — Tree and shrub planting to check erosion. 



The place of successful attack of an evil like the one in question 

 is at the origin of its source. In order thoroughly to test the value 

 of terraces located near the heads of the gullies and planted to soil- 

 binding species, a badly gullied area was selected on a southwest 

 slope at an elevation of approximately 10.000 feet. This study is 

 Hill in an experimental stage. As shown in figure 7, the distances 

 between the terraces which were established vary considerably, being 

 determined by the number of gullies and other topographic features. 



In establishing a terrace, strips are plowed about 4 feet wide, or 

 even wider on the steeper slopes, following which the loosened soil 



