Late Quaternary development of the southern sector of the Greenland Ice Sheet, with particular reference to the Qassimiut lobe

Abstract

The evolution of the southern Greenland Ice Sheet is interpreted from a synthesis of geological data and palaeoclimatic information provided by the ice‐sheet cores. At the Last Glacial Maximum the ice margin would have been at the shelf break and the ice sheet was fringed by shelf ice. Virtually all of the present ice‐free land was glaciated. The initial ice retreat was controlled by eustatic sea level rise and was mainly by calving. When temperatures increased, melt ablation led to further ice‐margin retreat and areas at the outer coast and mountain tops were deglaciated. Retreat was interrupted by a readvance during the Neria stade that may correlate with the Younger Dryas cooling. The abrupt temperature rise at the Younger Dryas—Holocene transition led to a fast retreat of the ice margin, and after ˜9 ka BP the ice sheet was smaller than at present. Expansion of the ice cover began in the Late Holocene, with a maximum generally during the Little Ice Age. The greatest changes in ice cover occurred in lowland areas, i.e. in the region of the Qassimiut lobe. The date of the historical maximum advance shows considerable spatial variability and varies between AD 1600 and the present. Local anomalous readvances are seen at possibly 7–8 ka and at c. 2 ka BP. A marked relative sea level rise is seen in the Late Holocene; this is believed to reflect a direct glacio‐isostatic response to increasing ice load.