114 WAVES OF SAND AND SNOW 



mulate in transverse ridges but in low, narrow 

 mounds, having on the lee a cliff, which is highest 

 in the centre and projects forwards on either side 

 in horns or cusps. The shape is that of the 

 crescentic sand-dunes known as medanos or 

 barchans, but with finer lines, the snow-barchan 



Fig. 6 

 Barchans of snow and sand. from photographs. 



being both narrower and flatter (Fig. 6). I saw 

 many hundreds of these structures which had been 

 produced in ordinary fresh -fallen dry snow, but 

 in the absence of any steep eminence to give me 

 a good view-point I was unable to obtain a photo- 

 graph showing how the prairie was dotted over 

 with these structures. 



