The Geography of Alaska 



217 



angular in outline, cut off from the con- 

 tinent by Mackenzie Bay on the north 

 and the Gulf of Alaska on the south. 

 South of it lies the Pacific Ocean. On 

 the west it is bounded by Bering Sea 

 and Bering Strait and west and north 

 by the Arctic Ocean. 



The territory is extended west and 

 southwest by its two peninsulas of con- 

 siderable size — the Seward Peninsula, 

 which with the Chukchee Peninsula 

 divides Bering Sea from the Arctic 

 Ocean, and the Alaskan Peninsula, 

 which, continued in its archipelagoes, 

 the Aleutian Islands and Commander 

 Islands, cuts off Bering Sea from the 

 Pacific Ocean. The coast of Alaska 

 is of two distinct topographic types. 

 Northward from the Alaskan Peninsula 

 shallow-water conditions usually pre- 

 vail, the coast line is very regular, and 

 the land slopes gently from the shore. 

 Eastward and southward from the Alas- 

 kan Peninsula the shores are usually 

 abrupt, with many embayments and 

 islands. This Pacific Coast region is 

 included in the glaciated area of Alaska, 

 while along the western and northern 

 coasts glaciation is either entirely ab- 

 sent or only of local character. 



The Pacific Coast line forms a deep 

 reentrant angle, which is occupied by 

 the Gulf of Alaska. It is bounded on 

 the east by the Panhandle of the terri- 

 tory, usually called Southeastern Alaska, 

 and on the west by the Alaskan Penin- 

 sula. It will be shown that the axes 

 of the dominant mountain chains un- 

 dergo, too, a marked change in direc- 

 tion, and are parallel to the crescent- 

 like bend of the southern coast line. 

 A study of the geology goes to show 

 that this is the topographic reflation 

 of an important structural feature. 



A clear conception of the main feat- 

 ures of the lopography of Alaska can 

 be obtained by comparing them with 

 those of the western United States. A 

 broad mountainous belt, called by Major 

 Powell the Pacific Mountains, including 



the coast ranges of California, Oregon, 

 and Washington, the Sierra Nevada, 

 and the Cascade Mountains, extends 

 along the western margin of the United 

 States and is continued by other ranges 

 northward into Canada. East of this 

 lies the Great Basin or Central Plateau 

 region, which also finds its counterpart 

 in British Columbia to the north. The 

 eastern limit of the Plateau region is 

 marked by the Rocky Mountains, which 

 again, like the western Pacific Moun- 

 tains, extend into Canada. To the east 

 of these the Great Plains extend north- 

 ward to Arctic waters. 



Dr George M.Dawson and others have 

 shown that these four topographic prov- 

 inces of the United States, which are 

 fairly well defined throughout western 

 Canada, find their continuation in sim- 

 ilar geographic features in Alaska. The 

 general trend of the highlands in Alaska, 

 as in the United States and Canada, is 

 parallel to the coast line. Attention has 

 already been called to the great south- 

 west bend of the Alaskan shore line near 

 latitude 6o°. The orographic features 

 of the mainland experience a similar 

 change in direction, continuing parallel 

 to the shore line. 



Alaska is thus divisible into the same 

 four geographic provinces as those of 

 western Canada and the United States. 

 The lines of demarkation between these 

 provinces are usually sharply drawn. 

 Each is of a predominant topographic 

 type, though each may be subject to 

 many minor topographic subdivisions. 



A mountainous belt skirting the Pa- 

 cific coast of Alaska and British Colum- 

 bia, extending inland from 50 to 200 

 miles, forms the westernmost of the four 

 provinces, which, in conformity with 

 Major Powell's classification, I will call 

 the Pacific Mountain System. It prop- 

 erly includes the mountainous Alexan- 

 der Archipelago and Aleutian Islands, 

 and a number of other island groups 

 which lie adjacent to the coast. The 

 Pacific Mountains belt is made up of 



