| Summary: | The pattern of glacigenic sedimentation in the Haliburton region suggests that stagnation is an important element in the regional style of deglaciation in areas of moderate bedrock relief (50-150 m), such as the shield terrane of southern Ontario. The record of subglacial processes and sub-ice environments suggests that stagnation began subglacially during active ice-margin retreat. The style of proglacial sedimentation suggests that topographically controlled subglacial drainage systems were the primary mechanism of sediment delivery to the ice-margin, and the prevalence of ice-contact terraces within these deposits indicates that deposition occurred on and around stagnating ice masses. It is hypothesized that deglaciation occurred by stagnation-zone retreat. Bedrock topography was an important control in the stagnation process, as ice blocks were trapped within bedrock basins of all sizes. Four stages of deglaciation and sedimentation have been recognized: (1) ice sheet thinning, subglacial stagnation of entrapped basal ice, development of topographically controlled subglacial drainage systems, and till deposition; (2) active ice retreat, isolation of ice blocks at the ice-margin, and deposition of high level kame and ice-contact diamicton terraces; (3) downwashing of ice blocks, establishment of regional drainage routes and inundation by proglacial lakes, and proglacial basin-fill sedimentation; (4) post-glacial modification and terracing, and renewed clastic sedimentation within modern lakes. Elevations of shoreline features within the Gull River valley, indicate that an arm of Main Lake Algonquin extended northward from the Kirkfield outlet area into the Haliburton region. Exponential projection of the Main Algonquin water plane from the Kirkfield area, demonstrates that the water plane projected by previous workers is a composite feature comprising progressively younger shorelines from north to south. Therefore, the slopes of previous water plane projections reflect progressively slower uplift rates from north to south producing an apparent flattening of the curve in the zone of assumed isostatic stability, south of the Algonquin 'hinge-line'.
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