CGRG Bibliography of Canadian Geomorphology
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Author : Coulthard, R.D.; England, J.H.; and Utting, D.J.
Date : 2007.
Title : Deglaciation of fiords entering Buchan Gulf, Baffin Island, Nunavut: a dynamic NE Laurentide Ice Sheet during Holocene deglaciation.
Publication : CANQUA Ottawa 2007. Canadian Quaternary Association Conference, June 4-8, 2007. Carleton University, Ottawa, Ontario, Canada.
Issue :
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Abstract
The maximum extent and retreat history of the Late Wisconsinan Laurentide Ice Sheet on eastern Baffin Island has been widely debated for over 40 years. Previous models have proposed either a large, thick ice sheet inundating the entire landscape (e.g. Hughes et al., 1977) or a thin ice sheet limited in extent to the major fiord heads (e.g. Miller and Dyke, 1974). Recent work on east-central Baffin Island now suggests an extensive but relatively thin Laurentide Ice Sheet in the region (Briner et al., 2005; Davis et al., 2006). Our new data add to the ongoing revision of the region and demonstrate a very dynamic ice sheet during Holocene retreat. In Buchan Gulf, Laurentide outlet glaciers extended at least as far as the mid-fiord region until 8.8 ka BP, however their maximum extent remains undefined. Inside the 8.8 ka BP margin, 22 new radiocarbon dates on marine shells indicate that the fiord glaciers retreated asynchronously and non-sequentially during the Holocene. Deglaciation occurred earliest in Dexterity Fiord (8.4 ka BP), despite its shallow depth and relative proximity to the Paleo-Barnes Ice Cap (a remnant of the Laurentide Ice Sheet). In adjacent Tromso Fiord, deglaciation occurred much later (4.5 ka BP) despite greater water depth and distance from the Paleo-Barnes Ice Cap. Notably, ice remained at tidewater in three of the four fiords until well after the end of the Cockburn Substage (8 – 9 ka BP), a period marked by glacier re-advance to several fiord heads elsewhere on eastern Baffin Island. The diachronous retreat histories in the adjacent fiords described here may be explained partly by physiographic factors; however, the fiords with the youngest dates of deglaciation are also those with the strongest evidence for vigorous, warm-based ice flow. At Tromso and Cambridge fiord heads, polished bedrock and far-travelled limestone erratics are found at high elevation on adjacent uplands. Conversely, blockfields and tors are more common adjacent to the heads of Royal Society and Dexterity Fiords. Our new evidence suggests that fast-flowing warm-based ice embedded in the Baffin Island (Foxe) sector of the Laurentide Ice Sheet persisted throughout deglaciation of the east coast of Baffin Island, and fed several tidewater fiord glaciers well into the Holocene.
Bibliography of Canadian Geomorphology