HOLOCENE EMERGENCE AT CAPE-HERSCHEL, EAST-CENTRAL ELLESMERE-ISLAND, ARCTIC CANADA - IMPLICATIONS FOR ICE-SHEET CONFIGURATION

Twenty-five radiocarbon age determinations on marine molluscs, basal organic pond sediments, chaffed remains in archeological sites, and a variety of other materials have allowed the construction of an emergence curve for Cape Herschel, east-central Ellesmere Island (78-degrees-35'N, 74-degrees-40'W). Only a narrow fringe of land is present between the Prince of Wales Icefield and Smith Sound, yet emergence of the order of 135 m has taken place during the last 8500 - 8700 radiocarbon years. The highest in situ shells were collected at an elevation of 107.5 m, and ages of 8470 +/- 100 BP (GSC-3314) and 8230 +/- 70 BP (TO-230) were obtained on this material. The spectacular and fresh-appearing glacial sculpture along both sides of Smith Sound, coupled with the rapid emergence in Holocene time and the fact that the oldest dates on marine shells at the fiord heads to the west are 3000-4000 years younger than those at Cape Herschel, provides convincing evidence that an ice stream filled Smith Sound (> 500 m deep) during the Late Wisconsinan glacial maximum. The Smith Sound Ice Stream drained southward from the Greenland Ice Sheet and the Innuitian Ice Sheet, which were confluent over Kane Basin, and it overrode the top of Pim Island (550 m asl). Massive melt-off of ice must have been occurring at the transition from Pleistocene to Holocene time, and this melting continued until the mid-Holocene, when all investigated outlet glaciers were behind their present positions.