Section 2. Southern Canada and the United States 



A. States, Provinces and Forest Districts, Chiefly Coniferous Forest 



Few or none of the states or provinces 

 are covered exclusively by coniferous 

 forest, and classification is accordingly 

 difficult on any basis. Several types of 

 coniferous forest are included; northern, 

 northwestern mesophytic, southwestern 

 xerophytic, and the montane of the 

 Rockies, Sierras, and Cascades. In 

 addition to coniferous forests Idaho, 

 Oregon, and California include a desert, 

 sage brush, semi-desert, grassland, and 

 considerable areas above timber line; 

 Washington and British Columbia, sage- 

 brush, semi-desert, and grassland, and 

 large areas above timber line, Alberta, 

 Saskatchewan, Manitoba, and Minne- 

 sota include popular savanna, and 

 steppe; Ontario, deciduous forest and 

 tundra; Quebec, tundra. The state, 

 national, provincial, and dominion for- 

 ests included in this section are almost 

 entirely coniferous. V. E. S. 



1. BRITISH COLUMBIA 1 



BY JOHN DAVIDSON, P. Z. CAVERHILL, 



EDWARD A. PREBLE AND A. H. 



HUTCHINSON 



I. GENERAL CONDITIONS (P. Z. C.) 



A. TOPOGRAPHY 



British Columbia occupies the north- 

 central portion of the Pacific slope of 

 North America, which is regarded as the 

 greatest forest region of the continent 

 and the greatest coniferous forest of the 

 world. The Province is a quadrangle 

 about 760 mi. long and 470 mi. wide. It 

 extends from the 49th to the 60th 

 parallels of latitude and from the crest 

 of the Rocky Mountains westward to 



1 Where there was no cooperation between the 

 authors their names are given in the order of the 

 receipt of their manuscripts and parts written by 

 each are indicated in the body of the text. 



the Pacific. Its eastern boundary fol- 

 lows the axis of the Rockies north from 

 49 to 54, and from there to latitude 60 

 it follows longitude 120. On the west 

 between latitudes 55 and 60 it is shut 

 off from the Coast by the long narrow 

 strip sometimes called the "Pan-handle" 

 of Alaska. 



The topography is prevailingly moun- 

 tainous except in the northeast corner, 

 which includes a triangular area of the 

 eastern foot-hills and the great plains 

 east of the Rocky Mountains. The 

 main physiographic features are the 

 series of parallel mountain ranges and 

 intermontane trenches or valleys which 

 extend with a general northwest trend 

 along both the east and west sides of the 

 Province, separated by a central belt of 

 plateau and minor mountain ranges. 



The Rocky Mountains on the east are 

 the northern end of the Cordilleran belt 

 which forms the backbone of the con- 

 tinent from Mexico to Alaska. It con- 

 sists of the upturned edges of the strata 

 underlying the Great Plains on the east, 

 chiefly alluvial and carboniferous lime- 

 stone. In the southern half of the 

 Province the average height of the peaks 

 is around 8000 ft., and the higher peaks 

 range from 10,000 to 13,500 ft.; north- 

 ward the mountains become progres- 

 sively lower. The average width of the 

 range is 60 mi. 



Along the western base of the Rockies 

 is the Rocky Mountain trench, a large 

 U-shaped trough from 2 to 15 mi. wide, 

 extending 900 mi. through the whole 

 length of the Province. 



Forming the western rim of the trench 

 is the Columbia system of mountains ex- 

 tending from the United States bound- 

 ary north to the Fraser River, latitude 

 53 45', with an average width of 80 mi. 



150 



