CGRG Bibliography of Canadian Geomorphology
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Author : Fenton, M.M.; Paulen, R.C.; and Pawlowicz, J.G. ,
Date : 2003.
Title : Evidence of pre-late Wisconsin glacial deposits in central and northern Alberta.
Publication : Joint Annual Meeting of the Canadian Quaternary Association and the Canadian Geomorphology Research Group. Halifax, Nova Scotia, June 8-12, 2003.
Issue :
Page(s) :
Abstract
During the past two decades, central Alberta was characterized by stratigraphy in which only one Laurentide glacial event, the Lostwood Glaciation, advanced into the province. This fact was attributed to middle Wisconsin preglacial deposits documented at Watino and in the gravel pits west of Edmonton. However, recent research during the past decade has documented several glacial and nonglacial sequences. A total of five glacial sequences were documented in the Cold Lake region on the Alberta Saskatchewan border. Stratigraphic position and detailed sedimentological studies allowed tentative correlations with three of these till units discovered immediately east of Edmonton where middle Wisconsin age dates were obtained from material below the uppermost till unit. Overburden drill programs in north central Alberta have discovered multiple tills in a number of holes. The tills are differentiated by their relative stratigraphic position, provenance lithology and preservation of oxidized horizons at depth. The degree of weathering of these lower tills is quite intense, much more so than modern weathering profiles. Typically, these units are preserved in the preglacial channels that were incised into the Cretaceous bedrock. However, recent fieldwork revealed the presence of two till sheets in the southern uplands of the Buffalo Head Hills and on the northwestern flank of the Pelican Mountains. The lower till has a noticeable increase in matrix sand and is carbonate poor. The lithological differences suggest ice flow from two different provenances: the older till being deposited by flow from the east, and the surface till by flow from the northeast such that during this event the glaciers moved over the Paleozoic carbonate bedrock that is exposed along this margin of the Canadian Shield. However, the possibility that the earlier glaciation was also of a northeast provenance exists if the Paleozoic bedrock was covered by clastic Cretaceous bedrock during pre-Wisconsin time. As Quaternary mapping continues into northern Alberta, additional evidence for multiple glacial events will likely be discovered. Currently, the southern and western limit of older glaciations in central Alberta lies between Villeneuve and Edmonton, and Watino and Peace River, respectively. Continued research will refine the maximum extents of older glacial advances in north central Alberta.
Bibliography of Canadian Geomorphology