GEOLOGICAL STUDY OF SOILS 63 



ern part of the United States, east of the Mississippi 

 River, there are large areas of sedentary soils as fer- 

 rogenous clays in an advanced state of decay. 



Transported soils are those which have been formed 



FIG. 22. A Boulder-filled Channel. 

 (Minnesota Geological and Natural History Survey.) 



in one locality and carried by various agents as gla- 

 ciers, rivers, or winds to other localities, the angles of 

 the stones in these soils having been ground off during 

 transportation. Transported soils are divided into 

 classes according to the ways in which they have been 

 formed; as drift soils produced by glaciers, alluvial soils 

 by rivers and lakes, aeolian soils by winds, and colluvial 

 soils formed of rocks and debris from mountain sides. 



