RESEARCHES IN ALASKA 



543 



MAP COMPARING SIZES OP COPPER RIVER GPACIERS WITH GLACIERS IN THE ROCKY 

 MOUNTAINS, SEPKIRK3, AND CASCADES OP THE UNITED STATES AND CANADA 



Note that the largest glaciers of the United States are in the Cascades, where the Nis- 

 qually Glacier of Mount Rainier exceeds in size the Blackfoot Glacier of the Glacier National 

 Park, in the Montana Rockies. These and the Illecillewaet and other glaciers of the Cana- 

 dian Rockies and Selkirks are much smaller than the Alaskan glaciers. 



advance is phenomenal, averaging two to 

 eight feet a day, and especially remark- 

 able for the edge of a glacier, where 

 movement is always slowest. The rail- 

 way engineers made most of the surveys 

 before we reached Childs Glacier and 

 one after we left, but we made supple- 

 mentary observations on a number of 

 days between their surveys, finding the 

 ice front advancing at rates intermediate 

 between those shown on the maps. The 

 rates per day are shown in the table on 

 preceding page. 



The rates of average movement show 

 variations in velocity, with two maxima ; 

 the fastest movements show a very rapid 

 increase in rate of advance to the maxi- 

 mum, between August 6 and ri, and an 

 unusually rapid decrease again. This is 

 one of the most rapidly increasing and 



decreasing series of glacier movements 

 yet mapped. 



It was a rare opportunity to see the 

 visible forward movement of Childs Gla- 

 cier into the forest. A series of lobes de- 

 veloped, though some of them were not 

 persistent, and at the ends of these lobes 

 the day-to-day changes were most pro- 

 nounced. Ice blocks were sliding' down 

 the frontal slope, some of them being 

 rolled many feet into the forest ; trees 

 were overturned, turf and grass were 

 ploughed up and carried on the ice of the 

 glacier. 



Yet one saw and heard little of a spec- 

 tacular nature while traversing the ice 

 front. It was an irresistible, steady 

 movement, but slow, as the movement of 

 the hour hand of a clock is slow. As im- 

 pressive as anything was to find tons of 



