March 19, 1908J 



KA TURE 



46J 



CANADIAN GLACIERS.' 



IN Dr. Sherzer's elaborate memoir on five glaciers 

 ill the Canadian Cordillera, we have a con- 

 tribution to the study of ice-streams not less im- 

 portant than that recently undertaken by the Indian 



Geological Survey, which was recently noticed in these 

 columns (p. 201). Easy of access, and thus well 

 adapted for study, these Canadian glaciers lie between 

 the 51st and 52nd parallel, that is to say, very nearly 

 on the latitude of London ; two of 

 them, the Victoria and the Wenk- 

 chemna, being east of the conti- 

 nental divide, the third, the Yoho, 

 west of it, while the lUecillewaet 

 and the Asulkan glaciers are in the 

 Selkirks. The peaks of each range 

 often vary from ten to eleven 

 thousand feet in elevation, rarely 

 exceeding the latter, and though 

 they form rather more continuous 

 walls and exhibit less contorted 

 strata, remind us of the Swiss Ober- 

 land, west of the Kanderthal. The 

 ranges, in fact, are carved out of 

 stratified rocks, the deposition of 

 which began quite early in the 

 Cambrian period (the crystalline 

 Archjean floor being invisible in 

 this region) and continued through 

 Palaeozoic and Mesozoic ages until 

 the end of the Laramie. Then this 

 enormous mass of sediment, sup- 

 posed to measure from ten to twelve 

 miles in thickness, was slowly bent 

 up into a very broad and flattened 

 arch — designated, inappropriately as 

 we think, by the modern mongrel 

 term, a peneplain — which was duly 

 carved into peak and valley by the ' 



ordinary forces of subaerial erosion. 

 Through Cenozoic (sic) ages until the beginning of 

 the Pleistocene (why the diphthong should be 



abolished in one name and retained in the other we fail 

 to understand) rain and rivers were the chief sculptur- 

 ing agents, but with the latter, ice began to make its 

 mark on the rocks. There was, in fact, a Glacial epoch 

 here as well as in the European Alps, and Dr. Sherzer 

 tells us that signs are found of two, and one case 

 of three, advances of the ice, fol- 

 lowed by retreats. We should 

 have welcomed a rather more 

 precise description of the materials 

 deposited on these occasions than 

 is conveyed by the terms " till " 

 and " ground moraine," because 

 the identification of the latter is 

 often, as we know from experi- 

 ence, a function of the writer's 

 imagination, but we infer that in 

 this case the deposits alter in 

 character as the distance from the 

 present ends of the glaciers in- 

 creases, much as they do in the 

 Alps of Europe. 



In the case of each glacier, very 

 careful observations have been 

 made on the present position of 

 its end, the signs of advance or 

 retreat, the nature and quantity of 

 moraine, and the structure and 

 other physical properties of the ice. 

 No one of them is really large, 

 the Victoria, of which the fullest 

 description is given, not exceeding 

 more than about three miles in 

 length. Starting at Abbot's Pass 

 (about 9500 feet) on the divide, its ice emerges 

 from beneath the snow about 2000 feet lower 

 down, and melts away after descending about 

 1500 feet more. According to the description. 



1 " Glaciers of the Canadbi 

 dition of 1904) ■• By Dr. Willi: 

 Ion: Smithsonian Institution, 



I Rockies and Selkirks (Smithsonian E.\pe- 

 m Hittell Sherzer. Pp. sii+i3s. (Washing- 

 1907.) 



NO. .?oo3, VOL. yy] 



it exhibits all the features usual in an Alpine 

 glacier — crevasses, moulins, stratification, blue bands, 

 shear planes, a granular structure, and sometimes 

 even the disputed capillary tubes. Observations were 

 made to determine the rate of movement, which, if 



