228 WAVES OF SAND AND SNOW 



is a common size. The height of the undulations 

 varied considerably, 8 inches being, however, about 

 the usual height, reckoned from trough to crest. 

 The profile was symmetrical both in the single 

 track across the frozen St. Lawrence and in the 

 streets, where the track is double and the sledges 

 keep to the right-hand side. In the streets, how- 

 ever, the ridges were not quite at right angles to 

 the course, the ridge being pushed slightly at both 

 ends in the direction in which the sledges are 

 driven, indicating a small amount of movement 

 since their formation. 



These undulations are known by their French 

 name cahots, or jolts, which is the same word as 

 is used for " holes " in ordinary roads. 



A long series of cahots was very quickly pro- 

 duced upon the frozen St. Lawrence in snow about 

 I o inches deep ; indeed, it was surprising to see 

 how soon the flat snow surface overlying smooth 

 ice was thrown into waves by the sledge traffic. 

 In one of the streets of Montreal I saw the old 

 cahots being hacked up and the consolidated snow 

 relaid. It was, indeed, more like ice than snow. 

 At Winnipeg, during the great cold of January 

 and February, the snow did not form cahots, except 

 where, a snowdrift having consolidated, there were 

 one or two slight undulations, obviously made by 



