The Glacial Geomorphology of the North-West sector of the Laurentide Ice Sheet

Abstract

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This paper presents a new map of the glacial geomorphology of ~ 800,000 km of north-west Canada. The mapped area includes parts of Northwest Territories and Nunavut which were covered by the Laurentide Ice Sheet during the Late Wisconsinan glaciation. It has been hypothesized that ice streaming occurred here during this time and the area has also been identified as a potential drainage pathway of glacial Lake Agassiz. Mapping was carried out remotely using a range of spaceborne imagery with varying spatial resolutions, including Landsat ETM+, ASTER and SRTM. Aerial photography was also used in areas where cloud obscured the Landsat imagery. The map records 94,780 individual landforms including moraines, eskers, large meltwater channels and lineations. Highly elongate bedforms with convergent flow traces and abrupt lateral margins are abundant throughout the mapped area and most likely represent former zones of streaming flow. Numerous eskers can be traced for tens of kilometres and are found both parallel and sub-parallel to abundant lineations. Moraine ridges are also identified which mark Late Wisconsinan ice margin positions and a series of smaller ridges are also identified within areas of hummocky topography. The map is intended to form the basis of a regional ice sheet reconstruction from the Last Glacial Maximum through to deglaciation, which we suggest is likely to involve marked changes in the spatial and temporal activity of ice streams.