96 THE ICE AGE IN CANADA. 



period. Mr. Low also finds that tlie newer stratified 

 gravels belonging to the later period of ice-drift extend 

 to heights of probably 700 feet, indicating the great 

 depression which succeeded the earlier glacial period. 



All these observations, combined with others detailed 

 in different parts of this work, constitute the most 

 complete proof that in Canada the condition of the 

 continent in the more extreme glacial period was one of 

 local glaciers, principally on the greater mountain regions, 

 with submerged plains and sea-drift intervening, and that 

 this was succeeded by a time of partial elevation of the 

 plains and diminution of the height of the mountains, 

 followed by a great and very general submergence, with 

 much ice-drift preceding the second continental or post- 

 glacial period. 



Dr. Otto Torell, Director of the Geological Survey of 

 Sweden, is one of the ablest Scandinavian students of 

 Pleistocene deposits, and has always been an advocate for 

 the theory of land glaciation, in so far as north-western 

 Europe is concerned. He has also had the advantage of 

 visiting portions of North America. I had the pleasure 

 several years ago of guiding him to the best exposures of 

 glacial and drift-deposits near Montreal. After his return 

 from America, he stated his general conclusions respecting 

 our Pleistocene deposits in a short paper published in the 

 Proceedings of the lioyal Academy of Sweden.* In this 

 he clearly states the conditions necessary to the production 

 of glaciers as follows : 



"1. Abundance of moisture in the atmosphere. 



" 2. A low temperature, due either to great elevations 

 in low latitudes, or to high latitudes with or without such 

 elevations of land. 



* April, 1877. 



