﻿456 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



the five years which have elapsed since, the hase of the ice front has 

 receded 55 ft, or an average of it ft. a year. 



Some distance down and upon the eastern side of the valley is 

 located the real nose of the glacier (fig. 65), the ice being completely 

 concealed by the debris from the right lateral and medial moraines. 

 Owing to the protection from the sun afforded by this veneering of 

 rock, combined with the sluggish condition of the ice along the side, 

 this nose is stagnant, or practically so, at the present time. The 

 last episode was one of advance, indicated by the manner and extent 

 to which the glacier has pushed into the forest of spruce and fir 

 (pi. lx). The fallen trunks and cut stumps, however, now seen 

 here were produced by a small snow slide, some decades ago, which 

 came down from between Castle Crags and Mt. Aberdeen, encir- 

 cling the nose when the ice stood somewhat farther back than at 

 present. Accurate measurements were made with a steel tape be- 

 tween blocks of an ancient moraine and others firmly planted in the 

 face of the frontal slope, here having an angle of about 38 . These 

 measurements showed that the latter blocks had settled backward an 

 inch in the 66 days from July 9 to September 13, and the inference is 

 that the ice beneath is slowly wasting faster than it is replenished 

 from behind. Confirmatory evidence of such wastage is furnished 

 by a small stream of clear, ice-cold water which issues from amongst 

 the rocks just west of the nose. So long as present conditions per- 

 sist, the recession will continue here with extreme slowness, but it 

 is obvious that a very slight additional impulse from behind would 

 inaugurate an advance. 



3. Forward Movement. — At the lower end of the sharply crested, 

 left lateral moraine shown in plate lx, a line of eighteen steel plates 

 was set, approximately 100 ft. apart and back 3,600 ft. from the 

 nose. The down-valley movement of these plates was accurately 

 determined with a transit for a period of ten cool days (July 9 to 19) 

 and then for a similar period of relatively warm ones (July [9 to 

 j')). 1 As was to be expected the movement was found to increase 

 from the sides, where it was practically nothing, towards the center 

 and to have been appreciably less for the cool period. The maximum 

 forward movement occurred in the broad, general depression in 

 which is seen the surface drainage channel, two-thirds of the way 

 across, and averaged for the cool period 2 inches daily, for the warm 



1 For the cool period the average daily minimum near the nose was 38.76 

 !•'., average maximum 60.36 F., total range 30.9 to 74.0 F., precipitation 

 .071 inches. For the warm period the average minimum was 39.59°, average 

 maximum 67.96°, total range 34.8 to 7? ■ '•■ precipitation .84 inches. 



