The land is clothed with dense growths of 

 tundra and native grass species, but island- 

 fashion stands of spruce and birch timber are 

 scattered over it. 



WEST CENTRAL 



West Central Division embraces an area 

 480 miles by 300 miles with a coastline cut by 

 scores of bays into which several rivers and 

 creeks flow. The large delta formed from residue 

 carried by the Yukon and Kuskokwim Rivers, 

 which pass through more than 350 miles of this 

 area, contains a myriad of lakes and bogs. 



The topography of this large land mass 

 generally consists of low flat muskeg bogs and 

 undulating hills, varying in height from near sea 

 level to 1,400 feet. However, the southern half 

 of the Seward Peninsula is mountainous and has 

 peaks rising to 3,800 feet. 



ARCTIC DRAINAGE 



Arctic Drainage Division comprises all of the 

 area north of the Brooks Range Divide, the 

 Kotzebue Sound Area, and the Kobuk and No- 

 atak Rivers. Three-fourths of the 1,200-mile 

 shoreline is north of the Arctic Circle. The Kotze- 

 bue Sound Area is a low tideland delta sur- 

 rounded by gently rolling hills. Most of the land 

 up to 3,000 feet elevation is covered by moss, 

 lichens, brush, and grass, but some dense stands 

 of spruce occupy the most favorable edaphic 

 sites. The arctic slope is a high, rolling plateau, 

 gradually lowering to near sea level, where it is 

 dotted by numerous lakes, muskeg bogs, and 

 rivers. The Meade, Chipp, Colville, and Canning 

 Rivers have their sources in the plateau area of 

 the Endicott Mountains and flow northward into 

 the Arctic Ocean. 



INTERIOR BASIN 



Interior Basin embraces most of the Yukon 

 River drainage and the upper portion of the 

 Kuskokwim Valley. The Endicott and Philip Smith 

 Mountains, a part of the Brooks Range, delineate 

 the northern limits of the area; between these 

 and the Alaska Range lies the drainage basin of 

 the great Yukon River. The Alaska Range is 

 composed of peaks more than 10,000 feet above 

 sea level, including North America's highest 

 peak, 20,300-foot Mount McKinley. 



Major features of the Interior Basin Division 



are the Yukon Flats on and near the Arctic Circle 

 and the adjacent mountains with elevations up to 

 6,000 feet. The Tanana River Valley, with an 

 area of about 24,000 square miles, lies north of 

 the Alaska Range, whose glaciers supply most of 

 the southern tributaries of the river. The upper 

 half of the valley is rough and broken, while the 

 lower portion has considerable level and gently 

 rolling country; some of it in the vicinity of 

 Fairbanks is adapted to agriculture. The upper 

 portion of the large Kuskokwim River Valley is 

 dotted by lakes and lesser rivers, many of which 

 are often bordered by timber stands to varying 

 widths. The intervening area is covered by 

 mosses, brush species, and native grasses. The 

 elevation of much of the valley area varies from 

 near sea level to only 2,300 feet. 



CLIMATE 



Climatically, Alaska is a land of dramatic 

 contrasts. Annette, near Ketchikan, in southeast 

 Alaska receives 97 inches of precipitation and 

 the temperatures may fall between 1° and 86° F. 

 But at Fort Yukon on the Arctic Circle, only 6 V 2 

 inches of precipitation falls and the temperature 

 varies from — 75° to 100° F. Information in this 

 chapter is confined chiefly to summertime condi- 

 tions within Interior Alaska. 



The movement of these high and low pres- 

 sure regimes (p. 4) brings different climatic 

 conditions through the State. Variation in tem- 

 perature, air moisture, precipitation, and the 

 geographic distribution of these factors is im- 

 portant to fire control, particularly during spring 

 and summer seasons (Kincer 1941). 



Watson's (1959) study of Alaska climate 

 divides the State into four major zones (fig. 20) 

 that are actually consolidations of the seven geo- 

 graphic divisions outlined in figure 19: 



1. Zone of dominant maritime influence. 



2. Transition zone. 



3. Dominant continental zone. 



4. Arctic drainage zone. 



Isolines of figures 21 through 27 show the 

 variation of precipitation during the spring and 

 summer months and the normal annual total. 

 The reader should refer to these while studying 

 the ensuing climatic descriptions. 



22 



