GLACIERvS OF THE CANADIAN ROCKIES AND SELKIRKS. 1 13 



and Rockies about the year 1897 or 1898, and that since then the average 

 for the series of years is in excess of the normal. These lines of evidence consist 

 (i) in the records kept by the station agent at Glacier House of the snowfall, 

 and of the records of the Canadian Meteorological Service for Banff and Calgary. 

 With the exception of Agassiz, which appears to be one of Bruckner's "excep- 

 tional coast stations," the other records do not reach far enough back to be of 

 service. (2) The notes and photographs of the Messrs. Vaux in the Asulkan 

 Valley, made in 1898 and 1899, when contrasted with those of later date, indi- 

 cate the close of a series of years with 1897-8, during which the snowfall was 

 much less than since. (3) The thickness of the strata in the ne've' of the Asulkan 

 Glacier, assuming that they represent annual accumulations, indicates at the 

 point photographed in 1902 that three years of diminished precipitation closed 

 with 1897-8 and were followed by four years during which the average precipita- 

 tion was in excess. (4) In 1883 and 1884 Dawson found over a belt of country 

 140 miles long in the western part of the Rocky System, evidence of a recent 

 high- water stage of the lakes, which resulted in the killing of trees that must have 

 grown during a prolonged low- water stage that preceded. The condition of the 

 trees indicated that they had ' ' been killed within a few years. " If we assume that 

 the wet phase that gave rise to this condition of the lakes closed about the year 

 1880, then we should expect the inauguration of another wet phase about the 

 years 1897 or 1898. Finally (5), from the photographs that have been made of 

 the Illecillewaet Glacier we have proof of the long-time oscillations of the level 

 of the ice about the ne" v line, giving rise to 



c. Ice waves. When photographs taken from the identical view-point in 

 1888, 1897, and 1905 (plates xxxvi and xxxvn) are compared, they show a 

 marked fluctuation in the height of the ice along the sky-line. The ice appears 

 to have been at a minimum about 1888 and to have been approaching the 

 same condition in 1905, possibly attaining it during the current season of 1906. 

 The crest of a wave, or impulse of ice from the ne've' appears to have reached the 

 sky-line about 1897 to 1899. The time from trough to crest would represent a 

 quarter of the period, that from trough to trough, half of the period of the com- 

 plete oscillation of the ice wave. In this case our data would indicate a period 

 of 36 to 40 years, agreeing well with the precipitation cycles to which these ice 

 waves are to be ascribed. It has been shown by the work of Finsterwalder, 

 Bltimcke, and Hess that the advance of a glacier is due to the progress of an ice 

 wave along its length, moving more rapidly than the ice itself. The Illecillewaet 

 in 1887 was experiencing about its nose the last stages in the effect of the arrival 

 of such a wave. The trough, then at the sky-line, moved valleyward and per- 

 mitted the retreat of the nose of the glacier, which retreat was probably at its 

 maximum about the year 1895 or 6, or some 8 or 9 years after the start. The 

 data for 1902 to 1905 seemed to indicate that an advance was about to be 

 inaugurated but the very marked retreat of 1905-6 shows that this ad- 

 vance has been somewhat delayed. When later the year is known at which date 

 the advance was most rapid we may figure the rate at which the wave travelled the 



