52 



NATURE STUDY REVIEW 



[9 : 2— Feb., 1913 



l^^ua'Kr: ."). — Roots growing from trunk of a cottonwpod 

 tree and exposed l)y migration of the dune. % 



against the driving wind. And in time the dune moves on 

 leaving the bared roots as in Figure :^ 



Upon the leeward side of the dune there are distinct tree 

 lines of Pine, Willow, Juniper and others, which may be seen 

 in Figure 4 to some extent. Across the river is a grove of sturdy 

 oak trees and several varieties of berries and wild grapes. 



The vegetation on sand dunes should always be encouraged 



Figure 4. — Advance of dune over Calumet River show- 

 ing moving dunes on the left and stable forest covered dunes 

 on the right. 



