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TitleContinental/Cordilleran ice interactions: a dominant cause of westward super-elevation of the last glacial maximum continental ice limit in southwestern Alberta, Canada
AuthorLittle, E CORCID logo; Jackson, L E; James, T SORCID logo; Hicock, S R; Leboe, E R
SourceBoreas vol. 30, no. 1, 2001 p. 43-52, Open Access logo Open Access
Alt SeriesGeological Survey of Canada, Contribution Series 2000120
Mediapaper; on-line; digital
File formatpdf
NTS82G/01; 82G/08; 82G/09; 82G/10; 82G/15; 82G/16; 82J/01; 82J/02; 82J/07; 82J/08; 82J/09; 82J/10; 82J/11; 82H
AreaLethbridge; Calgary
Lat/Long WENS-116.0000 -112.0000 51.7500 49.0000
Subjectssurficial geology/geomorphology; tectonics; ice margins; ice retreat; ice conditions; glacial features; glacial history; crustal uplift; morphogenic uplift; isostatic rebound; isostatic compensation; tectonic interpretations; glaciers; ice movement directions; Mokowan Butte; elevations; Quaternary
Illustrationssketch maps; graphs; satellite images
Released2008 06 28
AbstractIn southwestern Alberta, Canada, a westward-rising last-glacial-maximum continental ice limit has been identified. This limit is defined by the upper elevation of Canadian Shield erratics deposited by last-glacial-maximum continental ice along the flanks of prominent ridges and buttes within the region. The interpolation between ice-limit data points has produced two distinct slope profiles: 2.9 m/km to the east, and 4.2 m/km to the west of Mokowan Butte. Three hypotheses are proposed to explain this westward rise of the last-glacial-maxi -mum continental ice limit: (1) regional tectonic uplift, (2) glacioisostatic uplift, and (3) continental ice-flow convergence due to topographic obstacles and interaction with montane ice. Inferred long-term rates of tectonic uplift and glacioisostati c modelling show that these two mechanisms account for less than 25% of the observed absolute elevation increase of the limit between the Del Bonita uplands and Cloudy Ridge in southwestern Alberta. The remaining rise in elevation of the continental ice-sheet margin in this region is thought to result from continental ice-flow convergence due to the combined effects of the regional topography and interaction with montane glaciers to the west. The steeper rise in the former continental ice surface west of Mokowan Butte can be explained by the tographic obstruction and interaction with montane glaciers in the area of the Rocky Mountain front.

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