CLASSIFICATION BY THE BUREAU OF SOILS 



THE results of all the preceding factors involved in soil changes 

 find expression and application in the system of classification devel- 

 oped by the Bureau of Soils. The United States has been divided 

 into 13 great geographic divisions ; the six in the western part are 

 known as soil regions, while the seven in the eastern part are called 

 soil provinces. 



A soil province is an area which has the same general physio- 

 graphic expression and in which the soils were produced by the same 

 forces or groups of forces. 



A soil region may include several soil provinces which later 

 study may establish. The soils of a province are grouped together 

 into series on the basis of the same range of color, the same character 

 of subsoil, as regards color and structure, the same type of relief 

 and drainage, and a common or similar origin. A soil series is 

 divided on the basis of texture into classes. 



Soil Provinces and Regions. Area Surveyed up to 1915 



78 



