Earth, Environmental and Geographic Sciences Seminar Series presents Dr. Jerome Lesemann

The Department of Earth, Environmental and Geographic Sciences invites you to a lecture from Dr. Jerome Lesemann of Vancouver Island University, entitled Regional stagnation of the western Keewatin ice sheet and the significance of meltwater corridors and eskers, Northern Canada.

Retreat of the Keewatin sector of the Laurentide Ice Sheet is often depicted as a step-wise and sequential pattern, implying active back stepping of the ice margin toward Keewatin Ice Divide. However, these patterns are not well constrained by landforms and/or dates, and lead to re-evaluation of this retreat pattern and the deglacial dynamics of the Laurentide Ice Sheet in Keewatin.

The glacial land system of western Keewatin region, northern Canada, consists of three significant events:

1. Regional emplacement of subglacial sediments, mainly till;
2. Landscape erosion with development of an integrated, anabranched network of meltwater drainage routes leading to meltwater corridors; and
3. Deposition of an extensive array of eskers, and related landforms, within meltwater corridors. The network of long (∼100-200 km), relatively wide (∼1-3 km) meltwater corridors record confined subglacial erosion that scoured sediment (and bedrock) prior to glaciofluvial sedimentation (predominantly eskers).

Despite considerable sediment erosion along meltwater corridors, moraines  and other ice-marginal deposits are rarely observed on the western Keewatin landscape. The absence of these features is inconsistent with deglacial models relying on step-wise active retreat of the ice margin.

Instead, we propose that deglaciation of the western Keewatin sector of the Laurentide Ice Sheet was predominantly controlled by regional thinning and stagnation.

Please note: Those wishing to attend the lecture must obtain the Zoom password by emailing eegs.okanagan@ubc.ca.

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