CHAPTER III 

 SOIL FORMATIONS 



From the preceding description of the processes of soil 

 formation, it will be seen that the operation may involve 

 the transfer of soil from one place to another, or that it 

 may take place in one locality, leaving the resulting soil 

 where the parent rocks stood. The latter soils are called 

 sedentary, the former transported. These may again be 

 subdivided as follows : 



a , f Residual — formed in place 



Sedentary \ ~ , . • 



I Cumulose — plant remains 



Colluvial — gravity deposits 

 Alluvial — stream deposits 

 Marine — ocean deposits 

 Lacustrine — lake deposits 

 Glacial — ice deposits 

 . iEolian — wind deposits 



Transported 



18. Residual soils. — Soils of this formation are geologi- 

 cally old, that is, they were formed at an earlier period than 

 any of the other arable soils. They always bear more or 

 less resemblance in composition to the rocks underlying 

 them, although, on account of their great age they have lost 

 much of the more readily soluble constituents of the original 

 rock. This is also of agricultural significance, because 

 many of these soluble constituents are of great importance 



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