Abstract

Three alternative hypotheses for the timing and rate of deglaciation in the outer fiords and coasts of the eastern Canadian Arctic are tested by a computer program that provides information on the amount and form of crustal deflection according to a two-layer geophysical model. The three alternative hypotheses are (1) a glacial advance that started about 20,000 B.P. and reached a maximum at the outer coast at 18,000 B.P. and a slow glacial retreat that began at 14,000 B.P., (2) a glacial advance about 20,000 B.P. with the glacial margin stabilized along the Cockburn moraines near the fiord heads from 15,000 to 8000 B.P., and (3) a glacial advance to the coast from 20,000 to 19,000 B.P. with the glacial margin stabilized until 9000 B.P. and then a rapid glacial retreat to the fiord heads.

The derived-deflection and relative-sea-level curves, for a position equivalent to the outer coast of Baffin Island, indicate that the results from hypotheses 1 and 3 are incompatible with the observed distribution of raised Holocene and late Pleistocene marine sediments and their associated 14C dates. In contrast, the curve for relative sea level from hypothesis 2 explains significant elements of the distribution of radiocarbon dates and suggests that a marine transgression affected the outer coast until about 8500 B.P. The marine transgression was not caused by the peak in eustatic sea level but by the glacio-isotatic depression of the coast maintained by the stable mass of the northeastern sector of the Laurentide Ice Sheet.

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