

KINDS OF SOIL 97 



Wind has played and continues to play a far more im- 

 portant part in the transportation of soil than one is likely 

 to think. However, if you recall the sand-storms of the 

 desert of which you have heard, and then think of the 

 enormous stretches of time through which this agency 

 has been at work, you can understand how great results 



FIG. 42. Flood-plains. 



have been accomplished. Soils composed chiefly of sand 

 or dust which was once blown where they are, are called 

 eolian soils. 



Sand-dunes (see Fig. 43) are formed by the winds. Of 

 course, while the sand is still being blown about, there is 

 little chance for plants to gain a foothold. But gradually, 

 on dune-forming shores, the beach moves seaward or lake- 

 ward as the sand accumulates; and the farther a dune 

 gets from the beach, the less it is exposed to the wind. 

 So plants begin to cover it, their roots holding it together, 

 and presently we may have a dense vegetation growing 



