An Ice-dammed Lake. 135 



tary, and receives the northward drainage from the greater part 

 of the St Elias mountains east of the 141st meridian. There was 

 some question as to which branch should be regarded as the 

 main river and which the tributary, but the western is more 

 nearly in the axis of the main valley and is probably also some- 

 what larger than the Donjek, although no satisfactory compari- 

 son could be made as the confluence was not seen. The western 

 branch rises in Scolai pass from the northward-flowing lobe of 

 Russell glacier. In the fifty miles of its course lying west of the 

 international boundary it receives a number of tributaries from 

 the south, all of which flow from glaciers. This part of the 

 river is in unstable condition. It flows in many channels, con- 

 stantly shifting its position upon a wide gravel plain which is 

 being built up by contributions of coarse sediment from the over- 

 loaded stream. 



Scolai* pass is a low gap cut through the range which extends 

 northwestward to the Wrangell group. Russell glacier, from the 

 southeast, flows into the pass against the steep western wall, 

 which turns a part of the stream northward into White river 

 basin and turns a smaller lobe toward the south, so that for about 

 ten miles the pass is filled with ice at least several hundred 

 feet in depth. The altitude of the divide, which is near the 

 northern edge of the range, is 5,040 feet, or about 1,000 feet higher 

 than the upper White River valley. The southern lobe of the 

 glacier gives rise to the Nizzenah river, which flows at first west- 

 ward through a deep canyon-like valley for fifteen miles, and 

 then nearly southward about twenty miles, emerging into the 

 valley between the two divergent mountain ranges already de- 

 scribed. At the point where the river makes its sharp bend to- 

 ward the south, a glacier coming into the valley from the north- 

 west has dammed its waters so as to form a lake several miles in 

 length. Pushed out of its old channel by the ice, the stream 

 flows a short distance across a rocky point and then plunges 

 into a tunnel in the ice from which it emerges half a mile below. 

 After leaving the mountains it flows nearly westward for thirty 

 miles, to its confluence with the Chittenah, and the latter stream 

 continues in the same course about fifty miles further to Copper 

 river. These eighty miles are in a rather broad, open valley, 



* " Scolai " is the name by which the Copper river chief, Mcolai, is known 

 among' all the Yukon natives. 



