CLIMATIC ZONES 43 



canyons of the rivers into the mountains, but the forests of the 

 Yukon country are very different from those of the coastal belt. 

 The drier forest is made up mostly of white spruce (Picea Cana- 

 densis), the northernmost Alaskan conifer, and associated with 

 this are paper birch, balsam poplars and aspens. Two character- 

 istic Rocky Mountain conifers reach Alaska — the lodge-pole 

 pine (Pinus Murrayana) and a balsam fir (Abies lasiocarpa). 



The swampy ground is often covered with dreary forests of 

 black spruce (P. Mariana). These spruce-bogs, known locally 

 as " muskegs" are a characteristic feature of the Canadian north- 

 west. The sub-soil is permanently frozen, and the surface soil 

 in consequence is saturated. Travelling between the northern 

 Canadian Rockies and the coast of British Columbia, one becomes 

 sufficiently familiar with these dreary spruce bogs. 



As there are no high mountains east of the Rockies, the flora 

 of the vast region between the northern Rocky Mountains and the 

 Atlantic coast, including the basin of the Mackenzie River, the 

 regions about Hudson Bay, and Labrador, is very much the same 

 and quite similar to that of inland Alaska. 



The arctic tundras reach their southern limit in Labrador, whose 

 flora has a good deal in common with Greenland, and at the south 

 merges into the forest flora of Quebec and Ontario. 



In the west, the wooded area of the sub-arctic zone is confined 

 to the more northern regions and passes gradually into the prairies 

 of Saskatchewan, Alberta and Manitoba. Eastward the increas- 

 ing precipitation permits forest growth throughout, and there is 

 a gradual transition southward into the mixed forests of Quebec, 

 Ontario, and the northern United States. 



Immediately east of the northern Rockies lies the great plain 

 drained by the Mackenzie and its tributaries, a region of swamps, 

 tundras and innumerable lakes, some like the Great Slave and 

 Athabaska, of great size, passing at the south into the prairies 

 of western Canada. 



Much of the northern district is forested, with white and black 

 spruce, scrub pine (P. Banksiana), tamarack (Larix Americana), 

 and balsam fir. Paper birch, balsam poplar and aspen are the 

 common deciduous trees. Willows and alders border the streams. 

 and other shrubs, honeysuckle, roses, currants, wild cherries, 

 Viburnum, buffalo-berry (Shepherdia), snow-berries (Symphori- 



