Proposed Extent of Late Wisconsin Laurentide Ice on Eastern Baffin Island

The apparent outer limit of late Wisconsin Laurentide ice on eastern Baffin Island (roughly correlative with the “classical” Wisconsin of the southern Laurentide margin) is delimited in broad terms on the distal side by the presence of undisturbed glaciomarine deposits for which associated molluscan fauna have ¹⁴C ages beyond the useful radiocarbon age range. This is supported by the distribution of drowned cirques, submerged late Wisconsin glaciomarine deltas, moraines from local ice sources of comparable age, and the absence of main fiord ice moraines. Within this maximum outer limit of late Wisconsin glaciation, only the previously mapped Cockburn Moraine System is associated with marine deposits of finite ¹⁴C age. This system forms a largely continuous and prominent end and lateral moraine overlying till showing extensive tundra polygon development, and it is associated with ice-contact raised marine features dating between 7,500 and 8,500 ¹⁴C yr B.P. A map depicting the late Wisconsin ice margin based on these criteria shows that most of the eastern coastal margin of Baffin Island remained ice free throughout the last glacial stade (approximately 8,000 to 25,000? yr B.P.). This interpretation is supported by the occurrence of deposits dated more than 25,000 yr B.P., 30 to 60 km inland from the outer coast, which have not been glacially overridden; the pattern of postglacial isostatic uplift since 8,000 yr B.P.; and the complete absence of features dating between 10,500 and 25,000 yr B.P., despite more than 160 finite dates. Of 66 marine limit dates from the region, 44 percent lie between 7,500 and 8,500 yr B.P., whereas less than 8 percent are between 9,000 and 10,500 yr old. A consideration of the pattern of atmospheric circulation at the last glacial maximum suggests that few cyclonic disturbances penetrated the North American Arctic and that consequent decreased precipitation allowed only minimal glacial expansion.