File:Guide books of excursions in Canada. 1-10 (1913) (14776057501).jpg

Identifier: guidebooksofexcu10inte (find matches)
Title: Guide books of excursions in Canada. 1-10
Year: 1913 (1910s)
Authors: International Geological Congress (12th : 1913 : Toronto) Geological Survey of Canada Ontario. Bureau of Mines
Subjects: Geology
Publisher: (Ottawa, Government Printing Bureau)
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

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stones,thought to be of Devonian age, are developed.Typical granodiorites continue to Caribou. Lake Bennett and other similar bodies ofwater forming the headwaters of Yukon river,are of particular interest, and various theorieshave been advanced to account for their origin.It appears, however, that these lakes representthe positions occupied by the last great tonguesof the retreating valley glaciers, and that theice melted so rapidly toward the last that thedepressions it occupied had not time to becomefilled with glacial debris as did other valleys andother portions of these valleys. The valley of Lake Bennett, which is really asouthern continuation of the broad depressionextending northward from Caribou towardWhitehorse, is typically U-shaped, has highprecipitous walls rising abruptly from thewaters edge in places, and, particularly alongthe western side of the lake, has had all pro-jecting points and spurs planed away by north-ward moving valley glaciers. Virtually all the34883—5
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67 tributary streams entering this valley havehanging valleys, and in general the effects ofvalley glaciation are here so pronounced as tomake it an ideal region in which to study thesephenomena. (17, p.p. 11—23). The terraces seen along Lake Bennett atvarious elevations possess considerable interest,particularly as similar terraces characterizealmost all the main valleys not only in CentralYukon but in adjoining portions of BritishColumbia and Alaska. They are well devel-oped along Lewes river below Whitehorse, alongLake Laberge, along Nordenskiold river, andelsewhere. A number of theories have beenadvanced at different times to explain the originof these terraces, but the majority of such ex-planations fail when all the known facts andthe extent of the region throughout which theterraces occur, are considered. The writer hasinvestigated these in different districts in theYukon (17, pp. 21-23.) and Northern BritishColumbia (18, see section on Terraces) andbelieves them to be all la

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