SOIL FORMATIONS 25 



A striking peculiarity of this soil is the high percentage 

 of silica, due to the fact that quartz is highly resistant 

 to the constant working to which the particles have been 

 subjected and which has removed much of the phosphoric 

 acid, potash, lime and magnesia. Soils of this particular 

 type contain little fertility, but respond well to fertilization. 



26. Lacustrine soils. — These soils have been formed 

 in the beds of lakes both ancient and comparatively modern. 

 The older ones were formed in the glacial lakes, and both 

 are soils that have been worked over by water. They 

 constitute good agricultural soils and are found from New 

 England westward along the Great Lakes, and spread out 

 in a wide area in the Red River valley. 



27. Glacial soils. — - The tremendous grinding to which 

 rocks have been subjected by glacial action has resulted in 

 a large proportion of very fine particles, and consequently 

 these soils and subsoils are likely to be rather heavy. The 

 particles are jagged instead of having the rounded appear- 

 ance found in older soils and soils that have been worked 

 over by water for longer periods. 



Owing to the fact that this process of soil formation has 

 employed mechanical rather than chemical agencies the 

 soils resemble the parent rock very closely. Unlike residual 

 soils, glacial soils when formed from limestone are generally 

 rich in lime. If, on the other hand, glacial soils are formed 

 from rocks poor in lime, they have a small lime content. 

 The hill soils of southern New York (Volusia series) are 

 derived from shales poor in lime and the soils share this 

 quality, while certain glacial soils of the Mississippi valley 

 (Miami series) that are formed from limestone and sandstone 

 are rich in lime. 



In the following table are shown analyses of residual and 

 glacial soils from Wisconsin, the original rocks from which 

 they were formed having been largely limestone : 



