ICE-FLOW HISTORY AND CONTRASTING GLACIAL LANDSCAPES OVER THE KEEWATIN ICE DIVIDE AREA, CENTRAL NUNAVUT, CANADA

Quaternary mapping in central Nunavut over recent years by the Geological Survey of Canada (GSC) was centered in the region of the Keewatin Ice Divide, a broad zone of opposing ice flow on the northwest side of Hudson Bay during the last glaciation. Data provide an ice-movement chronology in an area of complex ice flow, and identify contrasting glacial landscapes and ice flow conditions in the area of the ice divide. From the Schultz Lake area to the Hudson Bay coast, outcrops have fresh, unweathered surfaces, and show evidence of glacial scour and polish. The record of successive paleo-ice flows is revealed by cross-striations, lee-side preservation of old striations, cross-streamlined landforms, and multiple-till stratigraphy, indicating large-scale patterns of ice-sheet flow and their changes through time. This suggests warm-based conditions under a transitory ice divide and leads us to support a much more dynamic behaviour for the Keewatin Ice Divide than previously realized. In contrast, 200 km farther north in the Wager Bay area, a 20-km wide belt of weathered upland terrain with few striae or glacial landforms suggests an ice regime that was different from areas to the south. The limited striation record and the absence of well-formed roches moutonnées in the central belt south of Wager Bay, combined with grus and weathering pits on rock surfaces in uplands near the ice divide, suggest limited glacial erosion in this area and an ice divide that appears to have been fairly stable. Ice in the Wager Bay area could have been cold-based and protective under the stable ice divide.