Continental/Cordilleran ice interactions: a dominant cause of westward super‐elevation of the last glacial maximum continental ice limit in southwestern Alberta, Canada

• Published in: Boreas
• Main Authors: LITTLE, EDWARD C., Jr., LIONEL E. JACKSON, JAMES, THOMAS S., HICOCK, STEPHEN R., LEBOE, ELIZABETH R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2001
• Subjects: Canada; Ice Sheet
• Online Access: http://dx.doi.org/10.1111/j.1502-3885.2001.tb00987.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1502-3885.2001.tb00987.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1502-3885.2001.tb00987.x

In 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.