The last glaciation of east-central Ellesmere Island, Nunavut: ice dynamics, deglacial chronology, and sea level change

During the last glacial maximum of east-central Ellesmere Island, trunk gla ciers inundated the landscape, entering the Smith Sound Ice Stream. Acceler ator mass spectrometry (AMS) dates on individual shell fragments in till in dicate that the ice advanced after 19 ka BP. The geomorphic and sedimentary signatures left by the trunk glaciers indicate that the glaciers were poly thermal. The configuration and chronology of this ice is relevant to the re construction of ice core records from northwestern Greenland, the history o f iceberg rafting of clastic sediments to northern Baffin Bay, the reopenin g of the seaway between the Arctic Ocean and Baffin Bay, and the regional v ariability of arctic paleoenvironments. Deglaciation began with the separat ion of Ellesmere Island and Greenland ice at fiord mouths similar to 8-8.5 ka BP. Ice reached fiord heads between 6.5 and 4.4 ka BP. Trunk glacier ret reat from the fiords of east-central Ellesmere Island occurred up to 3000 y ears later than in west coast fiords. This later retreat was favoured by (1 ) impoundment by the Smith Sound Ice Stream in Kane Basin until similar to 8.5 ka BP, which moderated the impact of high summer melt recorded in nearb y ice cores between similar to 11.5 and 8.5 ka BP; (2) the shallow bathymet ry and narrowness (< 2 km) of the east coast fiords, which lowered calving rates following separation of Innuitian and Greenland ice; and (3) the like lihood of higher precipitation along east Ellesmere Island. Glaciers throug hout the field area readvanced during the late Holocene. The greater advanc e of coastal glaciers is attributed to their proximity to the North Water p olynya in Baffin Bay.