200 



FIRST BOOK OF FORESTRY 



Baltic. In some places they are simply a desert waste, and 

 have comparatively little effect on the adjoining country ; 

 but in other localities, like The Landes of France, bordering 

 the Bay of Biscay, the sand dunes formed long, continuous 

 ridges along the shore, and thus dammed up the water in 



FIG. 72. Sand Dune in Holland, after Reclamation 

 (After Gifford) 



the streams and converted what, at one time, was a forest 

 into a pestilential, marshy waste. 



On the whole, these dunes occupy large areas ; those of 

 Europe alone have been estimated to cover over twenty 

 thousand square miles ; and since the wind easily drifts the 

 sand farther and farther inland, it is difficult to say how 

 much land might eventually be laid waste by these moving 



