SAND DUNES 



they remain open, and while they fill up on 

 the windward side, they are cleaned out on 

 the leeward and slowly move down wind. 



In a strong wind the peaks and crests of 

 all the dunes smoke like so many chimneys, 

 and a cloud of sand streams off, building the 

 dune up to leeward. As. Vaughan Cornish has 

 suggested, a great mountain may be laid low 

 by the slow process of denudation, while a 

 hrnnble sand dune still remains, for the proc- 

 ess which denudes it at the same time re- 

 news it. 



The sand blown from the dunes on windy 

 days cuts with stinging force, and one must 

 guard the binoculars, for glass is quickly 

 ground as by a sand blast. A clouded condi- 

 tion of the glass is shown on exposed window- 

 panes in the dune camps, or on bottles or any 

 piece of glass lying on the sand. A large flint 

 spear-head, I found in the dunes, has been 

 so smoothed that the sharp angles of fracture 

 are effaced. Pieces of wood are in the same 

 way ground down by the sand blast and take 

 on curious shapes determined by the position 

 of the harder knots. 



The grains of sand which compose the 

 dunes vary very much in color according to 



23 



