Iceland: glacial landforms from the Last Glacial Maximum

The configuration and dynamics of the Iceland Ice Sheet (IIS) during the Last Glacial Maximum (LGM) are generally poorly constrained due to sparse high-resolution mapping of glacial landforms and paucity of chronological data both onshore and (particularly) offshore. In the early 1900s, it was suggested that Iceland had been covered by a single ice sheet that extended beyond the present coast. Mapping efforts since the 1970s have then revealed glacial sediments and landforms across the shelf, including moraines, streamlined ridges, and troughs extending to the shelf edge. Dating of sediments and landforms offshore West, Northwest, and North Iceland indicates that the IIS terminated at or close to the shelf edge during the LGM. Maximum extent may have been reached in some areas before 28ka BP and deglaciation of parts of the ice sheet possibly commenced through initial thinning as early as 26ka BP. Dating of sediments and landforms on the shelf is still sparse and entirely lacking from the northeastern, eastern, and southern shelf around Iceland, hampering a chronologically robust reconstruction of the IIS. Thermomechanical modelling suggests that the IIS reached a maximum extent around 22.9ka BP and was drained by numerous ice streams that radiated from an east-west-orientated central ice divide. Future efforts should aim at testing previous reconstructions through detailed mapping and dating of glacial deposits particularly on the northeastern, eastern, and southern shelf to provide holistic chronological constraints of the spatial and temporal extent and dynamics of the IIS during the LGM.