152 THE ICE AGE IN CANADA. 



ice distribution, proceeding in the early glacial period 

 from its centre ; and later as a series of reefs and islands 

 in the arctic current. 



2. The maritime provinces of Prince Edward Island, 

 Nova Scotia and New Brunswick constitute a part of the 

 Atlantic slope of North America, and not having any 

 very high mountains, have had only minor centres of 

 permanent ice, but have been traversed by powerful ice- 

 laden currents from the north, and at certain periods of 

 partial submergence, more especially in the later glacial 

 age, have had boulders scattered over them from local 

 sources in their own hills. Parts of northern New Bruns- 

 wick have been invaded, in the more extreme glacial age, 

 by local glaciers from the north-east extension of the 

 Appalachian mountains. 



3. The Canadian region proper, or that constituting 

 the provinces of Quebec and Ontario, includes the wide 

 valley of the gulf and river St. Lawrence, and part of the 

 plateau of the great lakes. It curves to the south-west 

 and north-west around the great salient angle of the 

 Laurentian plateau, separating it from the basin of 

 Hudson's bay and the Arctic sea, and has to the south- 

 eastward the ridges of the Green and Appalachian 

 mountains forming the breast-bone of the North American 

 continent. In the earlier and more extreme glacial period 

 its lower lands were submerged and received on their 

 margins the ice discharged from the glaciers of the 

 Laurentide hills, the Adirondacks and the Appalachians. 

 The space between these now occupied by the St. 

 Lawrence, was a great channel like Baffin's bay and Davis 

 strait ; but owing to its direction,\ much more intensely 

 glaciated by floating ice borne on the Arctic current, 

 which spread its burden over the submerged North 



