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Abstract: This paper presents new Holocene relative sea-level (RSL) data collected from isolation basins close to the town of Paamiut in south west Greenland. The data shows a rapid fall from a marine limit of c. 52 m asl at c. 10.9 cal. ka BP to close to present by c. 9.5 cal. ka BP, at rates of up to c. 32 mm/yr, falling below present for the majority of the Holocene before rising to present in the last 2000 years. The elevation of the RSL lowstand is not well constrained, but was at least below −3 m. This pattern of rapid RSL fall during the early Holocene matches the pattern seen at other southern Greenland locations suggesting rapid, largely simultaneous ice retreat from the area surrounding the Qassimiut Lobe at the start of the Holocene, occurring c. 2000 years after the initial deglaciation of the extreme southern tip of Greenland. The RSL histories from this and other southern Greenland locations are distinct to those recorded further north along the west coast, and are in broad agreement with a pattern of vertical land motion and RSL predicted by the Huy2 model (Simpson et al., 2009), which predicts an 80 m drop in the contribution of vertical land motion to RSL at 10 cal. ka BP between Sisimiut and Paamiut on the west coast. Despite this broad-scale spatial agreement between the RSL data and the Huy2 model, it fails to satisfactorily predict the Holocene RSL histories at Paamiut and other southern Greenland locations. Sensitivity tests indicate that the data-model misfits are most likely due to an over-estimate of the forcing during the Holocene Thermal Maximum (or the response to this forcing) in southern Greenland and error in the North American ice sheets component of the background deglaciation model. Our new data suggests that much of the southern part of the ice sheet acted differently to the area further north. However RSL changes at Paamiut are also largely impacted by regional and larger-scale processes including a bulls-eye of uplift centred on the west, the impact of the Holocene Thermal Maximum and the influence of the collapse of the North American ice sheets. [Copyright &y& Elsevier]

This paper reviews the distribution, character and age of blue-ice moraines in Antarctica and asks whether there are implications for the study of former Pleistocene ice sheets in the Northern Hemisphere. Blue-ice forms where acceleration of downslope katabatic winds removes snow and causes ice to ablate. Upward ice flow compensates for the surface ablation and in some places brings rock debris to the surface to form a blue-ice moraine. Blue-ice moraines occur where topography focuses katabatic winds, notably outlet glaciers cutting through mountains and in the lee of nunataks and escarpments nearer the coast. Many Antarctic blue-ice moraines have been accumulating for millions of years. The cyclic growth and decay of Pleistocene ice sheets and the dominance of surface ablation near the ice-sheet margins are clearly different, yet there are aspects that apply to Pleistocene ice sheets. Based on Antarctic blue-ice deposits, equivalent deposits associated with former Pleistocene ice sheets are likely to: (1) lie in topographic sediment traps such as in side valleys or embayments next to outlet glaciers, (2) occur in the lee of mountains, (3) display a morphology indicating ice flow into the embayment or towards the mountain front, (4) include a wide range of lithologies derived from the inland ice sheet, yet consist wholly of local debris in places, (5) accumulate a thick deposit perhaps over successive glaciations. Further, (6) the location and intensity of moraine formation will change spatially and vertically in response to changes in the relative elevation of the surrounding mountains and its effect on ice flow. The extent to which these criteria will help in interpreting the behaviour of Pleistocene ice sheets is uncertain. But we use examples from the Greenland, Laurentide and Eurasian ice sheets to suggest that the concept of enhanced ablation by katabatic winds encouraging surface moraine formation helps resolve several puzzles. • Katabatic winds flowing over Antarctic nunataks create ablation hot spots. • Blue-ice moraines collect in such topographic sediment traps. • Similar sediment traps occurred on to Northern Hemisphere ice sheets. • The concept of topographic sediment traps helps interpretation of glacial sedimentation. [ABSTRACT FROM AUTHOR]