Application of ams dating to the paleogeography of the canadian high arctic

Abstract

During the last glaciation, the ice limit on northern Ellesmere Island was only 5–40 km beyond present ice margins due to the area's severe aridity. Many glaciers calved into a full glacial sea that transgressed the ice-free fiords and interislands channels to 140 m asl. Chronological evidence for the full glacial sea was first provided by conventional 14C dates on large samples ( > 40 g) that predated the onset of deglaciation and emergence by 1000 to 3000 years. Because some shell samples yielded conventional dates that ranged from 7025 to 10760 BP it was recognized that AMS dating of individual valves was necessary to determine their true range of ages. This paper discusses the application of AMS dating to the improved understanding of the full glacial sea. The full glacial sea is important geophysically and paleoclimatically because it records the complete history of glacial loading and unloading. Furthermore, the full glacial sea contradicts the popular notion that pervasive high latitude ice sheets inundated the Northern Hemisphere around 18000 BP. The new perspectives generated by the full glacial sea and the prospects of AMS dating will test many basic views concerning glacial dynamics and the evolution of the landscape in Arctic Canada.