THE DUNES AND THEIR PLANTS 113 



south end of the lake. These same stiff winds pick up this sand 

 after it has dried out on the shore, and carry it inland. So the 

 winds that blow vigorously inshore are sand laden, ready to 

 scour with the vigor of a sandblast but also ready to deposit 

 wherever their velocity is checked. 



Clumps of growing plants are the most effective agencies in 

 checking the wind and causing deposition. Wherever the bunch 



* 



,JP 



FIG. 68. A newly formed sand bar 



grass is growing, or where a grapevine or a low juniper spreads 

 its interlaced branches on the surface of the sand, there the sand- 

 laden air driving into the mass of vegetation is checked and so 

 deposits some of its burden before it escapes (Fig. 69). But such 

 sand heaps are small. The interlaced stems and branches of 

 young trees and shrubs make the most successful device for 

 enmeshing the sand and forcing the wind to deposit it in larger 

 dunes. A clump of red-osier dogwood or a thick stand of 

 cottonwoods are buried quite rapidly, and did they not grow 



