Dependence of Glaciers on Precipitation. 151 



snow disappears in summer, although they have an altitude of 

 from 6,000 to 7,000 feet and a mean temperature much lower 

 than any portion of the southern coast. The explanation must 

 be found in the very much greater precipitation and prevalence 

 of clouds along the coast than in the interior. 



The glaciers farthest removed from the coast are those flowing 

 from the mountains of the Wrangiell group, where the moisture- 

 laden winds of the north Pacific are able to pass up the Copper 

 River valley and across the coast range, which is here much 

 lower than toward the east. 



Four considerable glaciers descend to or nearly to tide level 

 on Taku inlet and river, though only Taku glacier, entering the 

 head of the inlet, discharges bergs. A few miles up from the 

 mouth of the river are two glaciers which come down into the 

 valley nearly opposite to each other. Neither quite reaches 

 the river, but, like the Norris* glacier 'on the inlet, they spread 

 out into fan-shaped expansions with low wooded deltas of mo- 

 raine material in front. Along the steep sides of the river val- 

 ley above these glaciers a slight but distinct terrace has been cut 

 about 150 feet above the river. It is probable that AVrightf glacier, 

 pushing across the valley to its northern side, dammed the 

 stream for a short time after the main valley was clear of ice. 

 Above Wright glacier only a few; small masses of ice or glacierets 

 occur in the Taku basin in cirques about the higher mountain 

 summits. No parts of the high interior plateau, either in the 

 Taku or Yukon basins, carry glaciers, and probably very little, 

 if any, snow remains throughout the year between the Coast and 

 Cassiar ranges, though much of the surface is fully 3,000 feet 

 above the snow line at the coast. The reason for this rapid rise 

 of the snow line toward the interior is the dry climate, with 

 short but hot summers prevailing throughout this region. In 

 like manner the high plateau east of White river is wholly free 

 from summer snow, and the first glaciers seen in the Yukon 

 basin were those flowing northward from the St Elias range. 

 Kluantu and Donjek rivers undoubtedly head in glaciers, but 

 these were not seen, since they lay too far east of the route 

 traveled. Three large glaciers flow into the White River basin 

 west of the Alaskan boundary, and numerous streams crossed 

 while following the southern bank of the upper White river 



* Named in 1886 for Dr Basil Norris, surgeon United States Navy, 

 t Named by the writer for Professor G. F. Wright of Oberlin college. 



