Fot'est Advance Over Glaciated Areas. 95 



taken place the wall of ice is only twenty or thirty feet high, and 

 where masses of ice have recently broken off it is several times 

 these heights. 



During the nine years preceding iqoi the retreat, as marked 

 by a mining stake, has been at the rate of from 40 to 50 feet per 

 year. But this rate of retreat is recorded for a far greater period 

 by the forest and scrub growth which flourishes on the former bed 

 of the glacier, and upon its enclosing slopes. At a distance of 

 about three miles from the present face of the glacier quite a for- 

 est of spruce trees has grown, many of which have been cut for 

 the mines on Douglas Island. Those now standing within two 

 miles of the face of the glacier are nearly full grown and are evi- 

 dently the only generation which has ever occupied the locality, 

 as there are no aged or fallen trunks, and the forest litter and 

 humus is thin and coarse. The size of one of these trees and its 

 growth are as follows : 



At 2'5 years q inches in diameter. 



other trees not felled were as much as 8 or 10 inches larger in 

 diameter, but the one measured was about an average. 



Advancing from three-quarters to a mile toward the glacier few 

 trees could be found over 20 inches in diameter, or about 70 to 80 

 years old ; within the next one-half to one-quarter of a mile the 

 trees had decreased in age to saplings 6 to 8 inches in diameter 

 or about one-quarter of a century old. Be}'ond these were young 

 and seedling spruce which soon gave out entirely, their places 

 being taken by alder-brush, dwarf cotton wood, grasses and 

 mosses. The surface between these and the glacier was composed 

 of clean boulders, gravel and sand, showing but slight signs of 

 disintegration and supporting no growth except mosses. 



Standing at the base of the glacier and looking at the mountaiti 

 slope to the eastward a similar record of the melting and thinning 

 of the glacier and the advance of forest was observed. For the 

 first 100 to no feet in elevation above the glacier bed the sides of 



