50 



NATURE AND PROPERTIES OF SOILS 



importance. The type of farming and the crops grown on any 

 area of alliwial soil will vary with climate, soil conditions, 

 and markets. 



29. Marine soils.^ — ^A great deal of the sediment carried 

 away by stream action is eventiially deposited in the sea, 

 the coarser fragments near the shore, the finer particles at 

 a distance. Such material is largely clastic and if there have 



Fig. 11. — ^Block diagram showing how marine soils are formed and their 

 relation to the uplands. The emerged coastal plain has already 

 siiffered some dissection from stream action. (After Emerson.) 



been many changes in shorelines, the alternating beds will 

 show no regular sequence. Such material, when raised above 

 the sea by diatrophism and subjected to sufficient weathering 

 and denudation, is classed as marine soil. (See Fig. 11.) 



Such material has been worn and triturated by a number 

 of agencies. First, the forces necessary to throw it into 

 stream suspension were active, and next it was swept into 



^For an excellent discussion of the marine soils of the Atlantic and 

 Gulf coasts of the United States see Bennett, H. H., Soils and Agri- 

 culture of the Southern States; New York^ 1921. 



