ALASKA AND ITS MINERAL RESOURCES 145 



Birch creek, Beaver, Tanana, and Nowikakat rivers ; from the 

 north come the Dall, Tozikakat, Melozikakat, and Koyukuk 

 rivers, the latter one of the largest tributaries and said to be 500 

 to 600 miles in length. 



The Yukon is generally a broad and muddy stream, flowing 

 with a current of 3 to 9 miles an hour. Occasionally it runs in 

 a narrow, rocky canyon cut through lava, or across low moun- 

 tain ranges, and such stretches are locally called " ramparts." 

 For the most part, however, its valley is wide, and the stream 

 often spreads out into many channels with low wooded islands 

 between, the whole covering a width said to reach 10 miles in 

 places. Dry spruce is practically the only fuel available for 

 steamers along the Yukon, and the supply is limited and diffi- 

 cult to obtain. Although the river is frozen up during eight 

 months of the year, from October to June, its importance as a 

 means of transporting supplies can hardly be overestimated. In 

 the early years, when the connection between the upper and 

 lower portions of the river was not absolutely known, the Hud- 

 son bay fur-traders were in the habit of taking their peltry from 

 Fort Selkirk down to the mouth of the Porcupine and up that 

 stream to the Mackenzie, preferring to make this long and cir- 

 cuitous journey rather than encounter the difficulties of a more 

 direct route across the mountains to the eastward. 



The international boundary between American and Canadian 

 territory has no relation to the physical structure of the interior 

 region ; hence in this description that portion of British Colum- 

 bia which lies opposite the Alexander archipelago and the coastal 

 strip of American territory southeast of Mount St Elias will be 

 considered as part of the general province of Alaska. The known 

 portions of the interior region, which lie mainly south of the 

 Arctic circle, belong to the drainage system of the Yukon river. 

 This stream, with its various tributaries, drains the northwestern 

 portion of the cordilleran system included between the coast 

 and the Mackenzie river valley, which are about 700 miles 

 apart and approximately parallel. The Mackenzie river flows 

 from Great Slave lake into the Arctic ocean. To one tracing 

 the broader features of physical structure northwestward from 

 the United States through British Columbia, it would seem that 

 the mountainous region between the Yukon and the Mackenzie 

 represents the Rocky mountains proper, and the Alexander ar- 

 chipelago and adjoining coast slopes the Coast ranges. The basin 

 of the Upper Yukon (the river above the great bend) would then 



