30 GLACIERS OF THE CANADIAN ROCKIES AND SELKIRKS. 



in agreement. So far as the present investigation is concerned the phenomena 

 observed can be satisfactorily explained only upon the theory that under certain 

 circumstances, and within certain limits, ice is capable of behaving as a plastic 

 body, that is, capable of yielding continuously to stress, without rupture. 

 In the discussion of this property of ice in the closing chapter of this report 

 it is pointed out that the "plasticity" of ice, a crystalline substance, must be 

 thought of as essentially different from that manifested by such amorphous 

 substances as wax or asphaltum. 



That the Victoria Glacier is flowing valleyward is capable of direct demon- 

 stration. From range lines across the glacier, the Messrs. Vaux marked the 

 position of a certain large boulder July 26, 1899. This was on the portion of the 

 glacier opposite the tributary and back some 6,800 feet from the nose. By July 

 24, 1900, this boulder was found to have moved forward 147 feet, while a second 

 "near the terminal moraine" was found to have moved 115 feet.' So far as 

 may be inferred from the phenomenon of the "dirt bands," to be later described, 

 the former boulder Avas not in the locus of maximum surface movement, but 

 some 360 feet to the west. In order to gather more definite data concerning 

 the movement of the lower Victoria a line of 1 8 steel plates was set by means of a 

 transit, the plates being placed as nearly as convenient at an average distance of 



d 





5 



5 



f It. -^-—^^^ 'I 



J.i '-^- mUUV YTVotcimt, 



^^^ o *flo aoo 300 4-00 Too ^^-'^ 



'~~^-~.^ Sea.V,toJFt4«. ^,^--' 



~~~"~— ^iJu«l_ed,JI_aVU«Ji«?'t-— ' -' ' 



100 feet. The line of plates was back 3,600 feet from the nose of the glacier (see 

 map) and was marked by setting the instrument over an established point upon 

 a large block on the shoulder of Mt. Whyte and sighting across to the sharp 

 edge of an easily recognizable cavity in the face of Mt. Aberdeen. The plates were 

 of the style successfully used by the Vaux brothers upon the Illecillewaet Glacier 

 and were 6X6X4 inches, with a 9-inch piece of f inch gas pipe screwed into the 

 center. They were given two coats of brilliant red paint, were numbered, and 

 had the actual reference line marked in white, after the short piece of pipe had 

 been driven into the ice. An arrow was marked upon each for purposes of 

 orienting, in case they should become turned. In general, where the melting 

 was greatest, it was found that the pipe did not sink into the ice and retain 

 its vertical position, but allowed the plate to drop to one side. The end of 



' Proceedings of the Academy of Natural Sciences of Philadelphia, Mch., 1901, p. 213. "Observations 



Made in 1900 on Glaciers in British Columbia." 



