46 THE ICE AGE IN CANADA. 



to be older than the south-west striae. In some other 

 parts of Canada these striae seem to be newer than the 

 others, but there would be nothing improbable in their 

 occurring both at the beginning and end of the boulder- 

 clay period. 



In summing up tliis subject, I think it may be affirmed 

 that when the striation and transfer of materials have 

 obviously been from KE. to S.W., in the direction of the 

 arctic current, and more especially when marine remains 

 occur in the drift, we may infer that floating ice and 

 marine currents have been the efficient agents. Where 

 the striation has a local character, depending upon exist- 

 ing mountains and valleys, we may on the other hand 

 infer the action of land ice. For many minor effects of 

 striation, and of heaping up of moraine-like ridges, we 

 may refer to the presence of lake or coast ice as the land 

 was rising or subsiding. This we now see producing such 

 effects, and I think it has not been sufficiently taken into 

 the account. 



As to the St. Lawrence valley, it is evident that its 

 condition during the deposit of the boulder-clay must 

 have been that of a part of a wide sound or inland sea 

 extending across the continent, and that local glaciers 

 may have descended into it from the high lands on the 

 north, and on the south which may have been relatively 

 higher than at present. During this state of the valley 



Fig. 1.— Travelled Boulder on Glaciated Rock. (After Dr. G. M. Dawson.) 



