182 



PLATE XCIL SNOW SURFACES. 



FIG. 1. From a photograph by E. H. SHACKLETON (Sh. 170, plate), Oct. 1902. 

 FIG. 2. From a photograph by E. H. SHACKLETON (Sh. 171, | plate), Oct. 1902. 



The innumerable changes in the appearance of hard snow surfaces, two of 

 which are represented here, and other two on Plate XCL, are due to changes in 

 the direction of the wind acting on the snow-dunes or "sastrugi," which were 

 originally laid down in elongated domes and crescent hollows. With a change in 

 the wind's direction, "the silting snow helps the wind and behaves like a sand- 

 blast, cutting away both the soft and the hard layers." 



Ferrar, Nat. Hist. Rep,, vol. i., p. 84. 





