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Publications - Occasional Papers

Deglacial Chronology and Uplift History: Northeastern Sector, Laurentide Ice Sheet

INSTAAR Occasional Paper 12

1974, 113 pp.

Using data contained in published literature and the Radiocarbon Data Bank of the Institute of Arctic and Alpine Research, an isochrone map is constructed which describes the pattern of deglaciation of the northeastern sector of the Laurentide Ice Sheet from the time of the late Wisconsin maximum (8000 yr to 8500r B.P.) to the present. The change in area and volume of the Northern Baffin Island Ice Cap from 7000 yr B.P. to the present is calculated using the isochrone map and two models relating ice area to volume. The volume measurements are then used to determine the contribution of the ice cap to world sea level rise since 7000 yr B.P.

Based on 325 shoreline locations, radiocarbon dated between 250 yr and 8750 yr B.P., eight isobase maps of the study area are produced depicting the amounts of uplift accomplished since 8000 yr B.P. and 1000 yr intervals thereafter. The pattern of isobases on the 8000 yr B.P. surface shows good agreement with the outline of the late Wisconsin terminal position. The 7000 yr B.P. and younger surfaces show the land recovering around five semi-independent uplift centers over the Queen Elizabeth Islands, Southampton Island, southeastern Keewatin, western Quebec, and northern Baffin Island. These uplift centers correspond to late-glacial centers of retreat.

The change in geometry of the uplift surface over northern Baffin Island is analyzed in detail and is found to be a function of the rate of decay of the Northern Baffin Island Ice Cap. Graphs derived from manipulations of the isochrone and isobase maps describe this functional relationship.

Finally the duration and amount of residual rebound at the regional center of uplift over Southampton Island is predicted on the basis of the measured displacement of isobases between 8000 yr and 1000 yr B.P. It is suggested that rebound in that area will be complete within the next 4000 yr resulting in a further 48 m or less of uplift.

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