Wrangell Mountains, Alaska 



407 



plain, the channels unite and enter a 

 canyon cut in the flood plain material 

 or in the rock beneath it, and in this 

 canyon the tributary continues to or 

 nearly to its junction with the master 

 stream. Sometimes just above this junc- 

 tion a second flood plain is developed. 



These rivers, like all others with 

 glacial sources, are at their highest 

 stages during midsummer, when melt- 

 ing of the snow and ice is at the maxi- 

 mum, and are lowest in the late winter, 

 when this is at a minimum. In the sum- 

 mer they are muddy, overloaded with 

 ground-up rock fragments ; in the win- 

 ter they are clear, and the trout, driven 

 from them in summer, return to them. 



The greater part of the drainage of 

 the Wrangell Mountains is gathered 

 into the Copper River, whose basin of 

 nearly 25,000 square miles includes a 

 large proportion of mountainous terri- 

 tory, in which glaciation is at present 

 active. Among the large streams of the 

 continent, it is perhaps the most nearly 

 purely glacial in its sources of supply, 

 and a comparison of its grade, which is 

 dependent, in part at least, upon this 

 fact, with those of other streams be- 

 comes interesting. 



The total fall of Copper River, from 

 its sources in Copper Glacier to the sea, 

 a distance of about 300 miles, is 3,600 

 feet— an average of 12 feet per mile. 

 The lower half of the river, from Copper 

 Center to the mouth, has an average fall 

 of nearly 7 feet per mile, while the 

 upper half, between Copper Glacier and 

 Copper Center, falls about 17 feet in 

 each mile. 



Compare with this the fall of the 

 Yukon, which between White Horse 

 and the sea is approximately 1.2 feet 

 per mile, and below Fort Yukon about 

 .5 feet per mile, or that of the Ohio, 

 which between Pittsburg and Cairo is 

 .435 feet per mile. The relatively tor- 

 rential character of the Copper as a type 

 of glacier-fed stream thus becomes 

 strikingly evident. 



Copper River drains the southern, the 



western, and a part of the northern 

 slope of the mountains. The central 

 part of the northern face drains into the 

 Tanana by its^two great tributaries, the 

 Nabesna and the Chisana, while some 

 of the glacial drainage from the extreme 

 northeastern limit of the mountains 

 passes down the valley of the White to 

 the Yukon. 



The district embraced by the group 

 offers many attractive problems to those 

 interested in physical geography or 

 geology and the allied sciences. The 

 problems of land forms as determined 

 by vulcanism and as modified by glacial 

 erosion, questions of ice accumulation 

 and shrinkage, of glacial deposition, of 

 the aggradation of glacier-fed streams, 

 unique problems of vulcanism and gla- 

 ciation, such as subglacial lava streams, 

 and modifications of glaciers by the 

 heat attending volcanic activity are a 

 few of the questions which immediately 

 occur for investigation here. 



The opening of the military trail from 

 the port of Valdez, on Prince William 

 Sound, and the establishment, by pros- 

 pectors and others, of various secondary 

 trails to points within the foothills of 

 the Wrangell Mountains have made 

 the whole region comparatively accessi- 

 ble. It is quite probable that the next 

 few years will see a railroad built to the 

 copper properties in the Chittina Valley, 

 which will remove the present necessity 

 of making a trip of 150 miles by pack 

 train and will place the traveler in the 

 interior valley of the Copper at any 

 season of the year. When that time 

 comes, the Wrangell Mountains should 

 prove an attractive field for students 

 and for those tourists who desire to get 

 a little beyond the usual summer fron- 

 tier. The maps which are now drawn 

 and will soon be publicly available will 

 serve as guides until the time shall come 

 when larger-scale work is required, 

 and the preliminary geographic studies 

 which have been carried out will serve 

 to indicate the tenor of the closer studies 

 of the future. 



