The formation of the glacial Lake Peace meltwater channel in Northern Alberta during the retreat of the Laurentide Ice Sheet and the potential for aggregate resources
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Date
2006
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University of New Brunswick
Abstract
During the last retreat of the Laurentide Ice Sheet in Northwestern Alberta, a 150 km long drainage channel crossing map sheets 84K and 84N was created as lake water catastrophically breached an ice dam spanning the ramparts of Mt. Watt to the north and Caribou Mountains to the west. This event released the contents of glacial Lake Peace first eroding and then depositing landforms northwards along the drainage channel. The vertical extent of channel units and the lateral extent of different bedding layers were identified at each site. These deposits varied from clay size to boulder size, with overall fining upwards in each unit. The variation of poorly sorted units and well-sorted units suggest that the deposition occurred under varying conditions of sedimentary supply and water discharge At least three main stages of deposition are identified: (1) an initial catastrophic breaching of the ice dam by a subglacial stream, that culminated with the deposition of a massive sandy gravel unit, (2) the deposition of fine p-gravel layers by coalescing tributary streams from the east and west as the main outwash channel formed and divided the ice mass, and (3) a final catastrophic drainage event which eroded previous channel deposits and deposited a massive planar gravel layer.