Abstract
IN Dr. Sherzer's elaborate memoir on five glaciers in the Canadian Cordillera, we have a contribution to the study of ice-streams not less important 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 continental divide, the third, the Yoho, west of it, while the Illecillewaet 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 Oberland, 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 Archaean floor being invisible in this region) and continued throug-h Palaeozoic and Mesozoic ages until the end of the Laramie. Then this enormous mass of sediment, supposed 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 ocarved 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 sculpturing 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, followed 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 experience, 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 increases, much as they do in the Alps of Europe.
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BONNEY, T. Canadian Glaciers . Nature 77, 463–464 (1908). https://doi.org/10.1038/077463a0
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DOI: https://doi.org/10.1038/077463a0