132 C.W. Hayes — Expedition through tJie Yukon District. 



ward, jDroducing the broad valleys of the upper Taku tributaries- 

 The deep canyon-like valleys in the lower portion of the river 

 basin represent a part of the erosion due to uplift in late Tertiary 

 and Pleistocene time. 



The divide between the Taku and Yukon drainage basins is 

 on the edge of an escarpment by which the surface drops from 

 the high plateau 2,600 feet to the level of Ahklen valley. The 

 altitude of the pass is 5,100 feet, which corresponds very nearly 

 with the average altitude of the interior plateau at this point. 

 The valley is from twelve to twenty miles broad, and on its 

 eastern side is the steep edge of a plateau corresponding to the 

 one on the west and extending eastward to the base of the Cas- 

 siar range, forty or fifty miles beyond. Bounded by these ap- 

 proximately parallel plateau escarpments, the valley extends in 

 an almost perfectly straight line for at least 250 miles in a north- 

 west-southeast direction. The upper, that is, the southeastern, 

 half of the valley is occupied by lakes. From one point on the 

 escarpment, affording only a partial view of the valley, fifty-four 

 Avere counted. Of these lakes, Ahklen-'^ is the northernmost and . 

 by far the largest. This lake is ninety-five miles in length and 

 from six to ten in breadth. Several small streams enter the 

 upper end, but its main feeder comes in from the northeast 

 about midway between the head of the lake and its outlet. This 

 stream, the Nisutlin, enters the head of an inlet about ten miles 

 in length which extends at right angles to the direction of the 

 lake. According to Mark Russell, who has prospected the stream, 

 its current is very sluggish for seventy-five or one hundred miles 

 above the head of the inlet. 



Beyond the lake the valley continues with little change, ex- 

 cept that the bounding escarpments draw somewhat closer to- 

 gether and decrease in height with the decreasing altitude of the 

 plateau toward the north. 



A consideration of the name to be applied to the river which 



* Among the various names which have been applied to the lake, Ahklen 

 is undoubtedly the one which should be retained. It is the name in com- 

 mon use among the Taku Indians. One branch of this tribe claims the 

 country about the southern end of the lake, spending a part of the year 

 there and coming out to the coast during the salmon season. The naiiie 

 is a T'linket word, meaning "big water." I have changed the spelling of 

 the word from "iVklene," as it appears on some maps, to Aliklen, which 

 more nearly represents the native pronunciation. 



