ICE STREAM INTERACTIONS AT THE NORTH-WESTERN MARGIN OF THE LAURENTIDE ICE SHEET, VICTORIA ISLAND AND PRINCE OF WALES ISLAND, ARCTIC CANADA

Several palaeo-ice streams have been hypothesised on Victoria Island and Prince of Wales Island in the Canadian Arctic at the north-western margin of the Laurentide Ice Sheet. However, complex cross-cutting flow patterns have so far prevented an overall synthesis of the interactions between individual ice streams and a plausible reconstruction of the glacial history of the region. It is important to resolve the location and activity of these ice streams, firstly to reconcile them with (often conflicting) ice sheet models and secondly, to examine their possible role in known iceberg and meltwater events in the Arctic Ocean. In this paper we present an overview of results from mapping a variety of glacial landforms (e.g. drumlins, mega-scale glacial lineations, ribbed moraine, eskers, and marginal moraines) on Victoria Island and Prince of Wales Island using digital satellite imagery and aerial photographs in combination with Digital Elevation Models. Ice stream tracks are identified on the basis of their unique characteristics: convergent flow patterns with extremely abrupt lateral margins (< 500 m) and comprising subglacial bedforms (drumlins and mega-scale glacial lineations) with high elongation ratios. It is demonstrated that ice streams preferentially developed in subglacial troughs often bordered by higher elevations which appear generally devoid of ice flow indicators, although this is not always the case. It is apparent that ice stream activity did not conform to a simple pattern of flow orthogonal to the ice sheet margin and retreating time transgressively. Individual ice streams appear to intersect (capture?) each other at oblique angles. This attests to rapid changes in ice sheet configuration and suggests that ice stream activity switched on and off during deglaciation. It appears that warm-based ice streams may have drawn down ice, isolating cold-based patches at higher elevations. In other locations, the presence (and orientation) of eskers suggests that warm-based deglaciation took place at oblique angles to the ice stream flow patterns. The emerging picture is that of rapidly-flowing ice streams facilitating deglaciation and forcing abrupt changes in ice sheet configuration and basal thermal regime.