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Agricultural Chemistry. 



the actual rock beneath. In this case the transportation of the 

 soil took place many ages ago. A large part of northern United 

 States is covered by drift, which was pushed down from the north 

 by the glaciers that once covered that section and was left behind 

 as the ice melted away. Such soils are distinguished from all 



The weathering of rock into sub-soil and soil (after Hall). 



others by the presence of rounded boulders of various sizes. 

 They are usually fertile, although very variable in composition. 



Wind also sometimes acts as a means of transporting sand, 

 volcanic ash, etc., from a distance and deposits them in a new 

 position, there to form a soil. 



Formation of soil. In the formation of a soil the first step 

 is the mechanical breaking down of the rock into small fragments. 



