68 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



which swept through the valley 70 to 80 years ago. Other trees in similar posi- 

 tion, but also dead, still retain their bark and boughs, but show no signs of fire. 

 It is likely that these trees were killed, and more or less. displaced, by the ad- 

 vance of the ice front (plate xxiv, figure 2), since which time the ice has advanced 

 less than a dozen feet. This is still further evidence of the almost stagnant 

 condition of the glacier. Only at one point, near the center, were there any 

 trees which have been recently cut by rolling blocks from the frontal slope. 

 This is taking place about the nose of the stream coming from Mt. Deltaform. 



In order to gather some definite data concerning the frontal movements, 

 a series of eight sets of reference blocks was established along the eastern half 

 of the front, beginning at a point just east of the drainage brook. Between 

 certain marked points upon boulders that had rolled forward and others firmly 

 embedded in the frontal slope, accurate measurements were made with a steel 

 tape.. From August 9 to September 12, 1904, an interval of 34 days, it was 

 found that there was no perceptible movement at the station east of the drainage 

 brook. Passing westward along the front, and up the valley, the data indicated 

 that there had been a wastage of the ice, causing the blocks to settle back 1.2 

 inches and 0.7 inch. The next two stations showed an advance of 1.9 and 1.3 

 inches, while the next two gave a retreat of i.o and 4.6 inches respectively. 

 At the upper station, where the trees had been freshly cut, the advance for 

 the 34 days amounted to n.8 inches. One year later, September 8, 1905, 

 measurements were again made between the series of blocks and at all of the 

 stations (the upper block at station D could not be located because of disturb- 

 ance) there was a small advance indicated, varying from 1.7 inches to 20.4 

 inches. The least movement was about the extremities of the easternmost 

 streams and the greatest was towards the center. 



A summary of the measurements is given below. 



Stations. Movement for 34 days, Aug. 9 to Movement for 361 days, Sept. 12, 



Sept. 12, 1904. 1904, to Sept. 8, 1905. 



A o.o inches i . 7 inches. 



A -1.2 



B -0.7 



C 1.9 



E -i .o 



F -4.6 



G ii. 8 



2-4 

 4.8 



12 . o 



Missing. 



3-2 

 20.4 



IS- 1 



These figures indicate that the component glaciers are as independent m their 

 movements as in their structure, and that some may be stationary, or in retreat, 

 while others lying alongside are advancing. The question of the frontal be- 

 havior of a. piedmont glacier is thus seen to be complicated in proportion to 

 the complexity of its structure. Measurements made at single stations can give 

 only very incomplete data concerning the glacier as a whole. There should be 

 at least one such measurement for each commensal stream. 



8. FORMER ACTIVITY. 

 a. Bear-den moraines. Along the western front of the Wenkchemna, for a 



