5 66 



ZONES AND REGIONS [Pt. Ill, Sect. II 



western parts exhibits differences, so that, with Sargent, we may distinguish 

 an Atlantic Northern forest (i on Map 4) and a Pacific Northern forest 

 (A on Map 4). 



The subpolar forest extends, not as a connected area towards the south, 

 but in the form of broad strips which are separated from one another by 

 wide districts of grassland and desert. The southern continuation of the 

 Pacific Northern forest, like the main forest itself, is composed of conifers, 

 and, at first, represents a belt which extends over about two degrees of 

 latitude, and, south of 53°, is divided by the desert district of the Great 



Fig. 306. The northern part of the Pacific Coast forest. Forest in Sitka, South Alaska. Right 

 hand: Tsuga Mertensiana. Left hand : Chamaecyparis nutkaensis ? From a photograph. 



Basin into a western and an eastern strip. Yet long before this division 

 a clear difference in the flora and oecology is established between the forest 

 of the Pacific Coast and that of the Interior. 



The Pacific Coast forest (B on Map 4) is, in British Columbia, Washing- 

 ton, and Oregon, between latitudes 6o° and 43°, but especially south of 51°, 

 the most luxuriant if not also the most diversified on the continent. 

 Pseudotsuga Douglasii, Carriere, Picea sitchensis, Bong., Tsuga Mertensiana, 

 Carriere (Fig. 306), Chamaecyparis nutKaensis, Spach, and Thuya gigantea, 

 Nutt., here attain gigantic dimensions. Trees up to 90 meters in height 



