I9I0.] INLAND-ICE OF THE ARCTIC REGIONS. 107 



Our best study of snow drift forms has been made by Dr. 

 Vaughan Cornish, who, after a series of monographs deahng with 

 waves of drifted sand, has spent a winter in Canada in order to 

 study the phenomena connected with the drifting of snow.^^ It 

 is found that snow which falls at temperatures near 32° F. is wet 

 and sticky, and behaves quite differently from that which falls 

 near or below the zero of the same scale ; which, on the contrary, 

 is dry and slippery. Subsequent modifications of either of these 

 forms of snow depend chiefly upon pressure, temperature, radia- 

 tion and wind. It is the cold, dry and granular snow only which 

 makes so-called normal waves, and it must be this form which 

 plays the major role in producing the surface irregularities of the 

 inland-ice of Greenland. 



Ripples and larger waves alike, when formed from granular 

 snow and when shaped by wind accumulation, have the steep side 

 ahvays to leezvard, in which respect the snow behaves like drifted 

 sand. In order to produce waves or ripples the wind must have a 

 velocity sufficient to be thrown into undulations by the irregulari- 

 ties of the surface over which it blows. The most perfectly 

 moulded forms are naturally produced upon a relatively plane sur- 

 face, such as is realized on the inland-ice of Greenland — ^the " im- 

 perial highway " of Commander Peary. 



Apparently the direction of the greatest extension of the sas- 

 trugi will depend upon the strength of the wind and upon the 

 amount of snow which is being transported, much as has been 

 found to be the case with drifted sand.®- Thus, with small amounts 

 of snow and moderate winds, the characteristic form of sastrugi 

 is a short, scalloped ridge lying across the wind direction and in 

 form not unlike an ox-yoke — something intermediate between a 

 barchan and a transverse ridge. Barchans of snow almost identi- 

 cal in form with sand barchans, are produced apparently under like 

 conditions, the chief differences being that lighter winds suffice 



'^ Vaughan Cornish, "On Snow- waves and Snow-drifts in Canada," 

 Gcogr. Jour., Vol. 20, 1902, pp. I37-I75- 



" P. N. Tschirwinsky, " Schneedunen und Schneebarchane in ihrer 

 Beziehungen zu aolischen Schneeablagerungen im Allgemeinen," Zcitsch. f. 

 Glctscherk., Vol. 2, 1907, pp. 103-112. 



