130 WAVES OF SAND AND SNOW 



The forms Produced by Wind-erosion in Compact 

 Snow. 



On the prairie near Winnipeg I measured series 

 of the transverse ridges which are formed when 

 wind is removing the upper layers of consoHdated 

 snow. They are minutely grooved, or rippled, 



The same at a later stage 



owing to their stratification. Inasmuch as they 

 recede before the wind, preserving their relative 

 positions, they may be considered to be a group 

 of surface waves, but the movement is due solely 

 to a difference in the quantity of the material 

 removed from the two faces, there being no 



