Studies of glacial history in Arctic Canada. I. Pumice, radiocarbon dates, and differential postglacial uplift in the eastern Queen Elizabeth Islands

Abstract

Dark brown pumice has been discovered recently on raised beaches of Ellesmere and Devon Islands, and in archeological sites on Baffin Island. It is similar in appearance and chemical composition to pumice associated with raised marine features throughout northern Europe, especially along the coasts of Norway and Spitsbergen. The source area for the pumice is uncertain, but Iceland is a good possibility.Radiocarbon dates on driftwood and whale bones imbedded in beaches at the "pumice level", as well as at higher and lower elevations, indicate that the pumice arrived approximately 5000 years ago.The pumice serves as a time-line and provides a means of correlating widely-separated marine features. Because these features now occur at different elevations, the amount and direction of tilt can be calculated. Also, former ice centers can be delineated, as the areas which have undergone the greatest uplift are those where the ice cover was once thickest. In Arctic Canada the "pumice level" rises westward along Jones Sound—from 16.5 m a.s.l. at the mouth of South Cape Fiord, Ellesmere Island, to 24.0 m at the eastern tip of Colin Archer Peninsula, Devon Island, ca. 130 km away. It also rises northwestward toward the head of South Cape Fiord.The Jones Sound information, plus radiocarbon dates from elsewhere in the Queen Elizabeth Islands indicating the approximate position of the shoreline at the same time, shows that there is a region in the eastern and central part of the archipelago where >25 m of uplift has occurred during the last 5000 years. This region, including considerable areas that are now sea, is believed to have been covered by a major ice sheet during the last glaciation.