THE SOIL, HOW MADE, AND FROM WHAT 29 



Red lands are found in the California Foothills, on the 

 Gila River in Arizona, the Laramie Plains in Wyoming, in 

 Oregon, and Washington, where the black lava or basalt rocks 

 underlie it, and in the states east of the Mississippi River. 

 Red soils are also very abundant in the Hawaiian Islands. .< 



Humid and arid regions. In the United States the 

 country lying along the Mississippi River and eastward 

 to the Atlantic coast has from thirty to sixty inches of 

 rain every year, much of which falls during the summer. 

 The same and even heavier rainfall occurs in Oregon 

 and Washington west of the Cascade Mountains. This 

 is enough to produce crops without irrigation when 

 the rains come at the right times. This country we 

 call the humid region. 



West of the Rocky Mountains the rainfall is mostly 

 less than twenty inches. There is but little rain in 

 summer except in the higher mountains, and near their 

 western slopes. What rain there is in summer fre- 

 quently comes in heavy showers or cloudbursts, the 

 water of which runs off without doing much good to 

 crops. For this reason irrigation is necessary, or at 

 least desirable, to make sure of good crops. These 

 regions, where rain is scanty and falls mostly in winter, 

 we call the arid regions. Just east of the Rocky Moun- 

 tains lies the Great Plains Region, the western part of 

 which, in the states of North and South Dakota, Ne- 

 braska, and Kansas, we call the semiarid (half-arid) 

 belt. 



