Abstract

An analysis of glacial landforms on a regional scale leads to an interpretation of the dynamics of Late Wisconsinan glaciation on Wollaston Peninsula, Victoria Island, Northwest Territories. The glacial record is dominated by four adjacent belts of landforms: (I) ground moraine (till plains and ice-marginal drainage features), (II) hummocky moraine, (III) lateral and shear moraine, and (IV) streamlined landforms. The landform belts are considered as representing four distinct glacial ice conditions or regimes: (1) ice-margin retreat during extending flow of thin, active ice; (2) marginal ice stagnation following compressional flow; (3) a surging ice margin producing massive shear moraines; and (4) large-scale flooding and mass ice stagnation following a surge. These landform belts were arranged in zones by topographically controlled glacial dynamics, the latter two defining a former ice stream.Glaciological inferences can be extended by examining the sediments and processes that produced each landform set. Ground-moraine sediments were produced mainly subglacially from melt out or lodgment of glacial debris. Hummocky moraine resulted from debris flow and meltwater deposition controlled by ice, from resedimentation by sediment gravity flow, and from slump. Compressional shearing stacked thick deposits of drift prior to resedimentation. Simple lateral or end moraines may comprise interbedded sediment gravity flows deposited at static ice margins. Deformed lateral moraines resulted from intense marginal compressive flow that sheared and stacked thick, coarse sediment ridges or plates. This lateral shearing may be attributed to streaming or large ice surges. Drumlin exposures showed undeformed, interbedded, stratified sediments that appear to have accumulated in a subglacial cavity; there is no deformation related to high subglacial stress. Subglacial meltwater floods may have followed glacier surge. The greatly extended and thinner ice mass produced by the surge melted in place as clean (debris-free) ice.

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