CGRG Bibliography of Canadian Geomorphology
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Author : Ferguson, A.J.
Date : 1978
Title : Late Quaternary geology of the Upper Elk Valley, British Columbia
Publication : Unpublished M.Sc., University of Calgary, Calgary
Issue :
Page(s) :
Abstract
Surficial deposits in the upper Elk Valley, B.C. were examined in order to determine (i ) tihe nature and distribution of Quaternary sediments, and (2) Late Quaternary glacial and climatic history of the region. Information on Late Quaternary history was obtained by means of tephra analysis, radiocarbon dating, palynological studies, and a stratigraphic study of the deposits. Surficial deposits, mapped at a scale of 1:50,000, consist mainly of tills and associated ice-contact sediments, the latter including lake sediments deposited in ice-dammed Glacial Lake Elk. Overlying these deposits are Holocene and modern fluvial and fan deposits, bog deposits, and mass wasting debris. Tephra was identified as to source by determination of refractive indices of glass shards and, more definitively, by microprobe analysis of the magnetite fraction. Tephra collected from alluvial deposits and bogs was identified as Mazama (6600 B.P.). Tephra collected from pedogenic soils horizons was found to be intermixed with silt and could not be accurately identified. One of the mixed samples may represent a pre- Mazama tephra of unknown origin. A 4,2 m core from a peat bog contained Mazama tephra, beaver-chewed wood radiocarbon dated at 10125±285 years B,P., and 5 recognized pollen zones: birch-sagebrush tundra (I), spruce-fir (II), pine (III), pine-Douglas fir (IV), and pine-spruce-fir (V). Zone l represents time after deglaciation but before 10125 B.P. Two subzones, designated IIIa andVa, suggest cool, moist climates. These subzones are tentatively correlated with minor Early Holocene and Late Holocene glacial advances. Zone IV and most of zone III represent relatively warm, dry climates associated with the Altithermal. Till stratigraphy indicates at least two major glacial advances in the valley. Ice of the older advance, which extended south of the study area, attained elevations above 1935 m(6350 ft). It is correlated with the Big Rock Stade in Alberta. The younger and less extensive advance is correlated with the Canmore Stade in Alberta, There is evidence for two minor glacial advances. One, which extended to the upper Elk Lakes and produced rockglaciers in other cirques, is correlated with Early Holocene advances in Alberta. The other,which resulted in fresh cirque moraines still largely unvegetated, is correlated with the Cavell Advance in Alberta (about 100-200 years B.P.). A time/depth analysis of bog stratigraphy, utilizing Mazama tephra and dated organic matter, suggests that the southern section of upper Elk Valley was deglaciated by 12000 to 13000 years B.P,, the central section by 11000 to 12000 years B.P., and Elk Pass by 8400 years B.P.
Bibliography of Canadian Geomorphology