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A NATIONAL PLAN FOR AMERICAN FORESTRY 



10 to 100 miles, along the western edge of the basin. Along the Con- 

 tinental Divide the mountains are broken and exceedingly steep. 

 Crests and peaks, and in some localities high rolling plateaus, at 

 elevations of 9,000 to 11,000 feet or more, rise above narrow valleys of 

 5,000 to 6,000 feet elevation. Within the Plains region, many miles 



from the Rockies proper, are a number of forested outposts, of which 

 the Black Hills of South Dakota are an example. In portions of the 

 plains are scattered areas of Badlands and of sand hills. 



The soils are usually loams varying from gravelly phases in the 

 mountains to heavy clay loams elsewhere. 



The precipitation varies from 10 or 12 inches in the semiarid 

 plains of the Big Horn and Milk River Valleys to 50 inches or more in 



