ABSTRACT: Consensus on the Iinnuitian ice sheet during the last glacial maximum: new evidence and opportunity

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Abstract

Consensus in support of the Innuitian Ice Sheet (IIS) during the last glacial maximum ends three decades of debate. The IIS coalesced with Greenland ice throughout Nares Strait (500 km long) where ice thickness reached 1 km. This coalescence caused thickening of the eastern Ellesmere Island ice divide, and enhanced westward flow, recorded by granite dispersal trains, to the intermontane basin of Eureka Sound. Ice debouching eastward from the mountains of Axel Heiberg Island also filled Eureka Sound, which became the axis of glacioisostatic loading in the alpine sector of the IIS. From Eureka Sound, ice diverged northward into Nansen Sound, and southward into Norwegian Bay. From Norwegian Bay, the ice divide of the IIS extended westward into the central arctic, north of Bathurst and Devon islands. An ice stream flowing southeastward from this divide occupied Wellington Channel, flanking Devon Island. A flowline of equal length on the opposite (NW) side of this divide would reach the westernmost arctic islands. AMS dates on subtill organics and shelly till suggest that significant buildup of the IIS on east Ellesmere Island occurred < 25 ka BP, when several proxy records indicate extreme aridity. Rapid breakup of the IIS in the marine channels and fiords occurred between ~10 and 9 ka BP in the central arctic and Eureka Sound, and between 10 and 8 ka BP in Nares Strait. Subsequently, land-based ice margins stabilized along coastlines where widespread sedimentation records slower retreat, extending inside modern ice margins by ~6 ka BP. Isobases drawn on the ~8.5 ka BP shoreline reach 120-130 m asl, and portray an arcuate ridge extending 700 km from Eureka Sound in the north to Bathurst Island in the southwest. New opportunities exist to determine the configuration and pattern of ice divides during the maximum extent and retreat of the IIS. This would also provide new opportunities for glaciological, geophysical and paleoenvironmental modelling. The history and dynamics of the IIS is pertinent to the paleo-oceanography of Baffin Bay and the Arctic Ocean, and to the undefined northeastern limit of Beringia

Bibliography of Canadian Geomorphology