CHAPTER XV 

 CEREAL CULTIVATION WESTERN AREA 



THE region westward from the Rocky Mountains to 

 the Pacific Ocean, discussed here under the heading 

 Western Area, is, almost throughout its extent, very dry 

 like the Great Plains, though there is a district of heavy 

 rainfall in the extreme Northwest. The chief character- 

 istic distinguishing it from the other two areas is the 

 winter rainfall. Also the soils generally contain consid- 

 erably less humus than those of the Great Plains. In the 

 upper depths they contain even less humus than those 

 of the Eastern area, but more mineral plant-food. There 

 are often excessive deposits of alkali. 



SOIL TREATMENT 



403. Soils. The soil types vary greatly in this area. 

 In the mountain valleys the soil ranges from sandy loam 

 to clay, and is sometimes underlain with coarse gravel. 

 In the Great Basin the soils are alluvial and those of 

 the eastern portion included in a large part of Utah were 

 made chiefly by the ancient Lake Bonneville, while in 

 the western portion, in Nevada, much of the soil is a 

 product of Lake Lahontan. In nearly all of Idaho 

 and the eastern and central parts of Washington 

 and Oregon is one vast lava bed. Here, therefore, the 

 soils are all of volcanic origin. They are composed of 



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