292 THE ICE AGE IN CANADA. 



between these, in the middle Pleistocene period, large 

 portions of the northern parts of the Northern Hemis- 

 phere possessed a climate not much colder than that 

 enjoyed at present, and that in the height of the cold 

 period only a limited portion of the north-east of Europe, 

 the Alpine regions, the Cordillera of North America, the 

 Laurentide hills and the Appalachians were deeply ice- 

 capped, while the ice was flowing on all sides, north as 

 well as south, into submerged areas. 



In so far as Canada is concerned — and Canada includes 

 the northern half of the American continent, the greatest 

 of all the theatres of glacial action — the history of the 

 Pleistocene period, as stated in the previous chapters, may 

 be summed up as follows, beginning with the continental 

 period of the newer Pliocene : — 



1. In Canada and the eastern part of North America 

 generally, it is universally admitted that the later Pliocene 

 period was one of continental elevation, and probably of 

 temperate climate. It is also evident, from the raised 

 beaches holding marine shells, extending to elevations of 

 600 feet, and from boulder-drift reaching to a far greater 

 height, that extensive submergence occurred in the middle 

 and later Pleistocene. This was the age of the marine 

 Leda clays and Saxicava sands found at heights of 600 

 feet above the sea in the St. Lawrence valley nearly as far 

 west as Lake Ontario. It was also the time of the 

 extensive drift over the great area of the western plains. 



2. It is reasonable to conclude that the till, or boulder- 

 clay, under the Leda clay, and its equivalents, belongs to 

 the intervening period of probably gradual subsidence of 

 the lower lands, accompanied with a severe climate and 

 with snow and glaciers on all the higher grounds, sending 

 glaciated stones into the sea. This deduction agrees with 



