Deglaciation and Isostasy in the Sukkertoppen Ice Cap Area, West Greenland

Abstract

Three groups of landforms of deglaciation are analyzed, namely those associated with (1) the disappearance of Inland ice (main Greenland ice sheet), (2) the withdrawal of local Sukkertoppen ice, and (3) the changing of relative sea level. Consideration of their interrelationships in space and time allows a reconstruction of the process of deglaciation. There was an overall westerly movement of Inland ice across the area and this persisted during the early stages of deglaciation. Later stages of deglaciation reflect progressive downwasting with ice persisting in the troughs while adjacent plateau areas became free of ice. The highest marine limit is at 123 m and this incursion of the sea took place ca. 8,800 to 9,000 radiocarbon years BP. Local Sukkertoppen ice appears to have played an insignificant role during this main phase of deglaciation. Subsequently several Sukkertoppen outlet glaciers have advanced over marine deposits.

The paper concludes with consideration of some wider implications. The importance of downwasting and meltwater activity during deglaciation is stressed. Also it is noted that isostatic recovery follows the Greenlandic pattern with high initial rates of uplift, apparently ceasing ca. 3,000 to 5,000 years BP. Unlike arctic Canada and Scandinavia where uplift has continued to the present day, the continued existence of a major ice sheet in Greenland is probably responsible for this recent stabilization. Finally, it is suggested that the last Inland ice sheet accomplished little erosion in the area compared to earlier ice sheets.