The surface geometry of the Last Glacial Maximum ice sheet in the Andoya-Skanland region, northern Norway, constrained by surface exposure dating and clay mineralogy

Blockfields, weathering boundaries and marginal moraines have been mapped along a longitudinal transect from northern Andoya to Skanland in northern Norway. The degree of rock-surface weathering above and below glacial trimlines, clay-mineral assemblages and surface exposure dating based on in situ cosmogenic 10 Be have been used to reconstruct the vertical dimensions and timing of the Last Glacial Maximum (LGM) of the Scandinavian Ice Sheet in this region. The cosmogenic exposure dates suggest that the lower blockfield boundary/ trimline along the Andoya-Skanland transect represents the upper limit of the Late Weichselian ice sheet, with an average surface gradient of c. 9.5 m/km. The surface exposure dates from Andoya pre-date the LGM, suggesting that the LGM ice sheet did not reach mountain plateaux at northwest Andoya. The results thus support evidence from lake sediment records that the northern tip of Andoya was not covered by the Scandinavian Ice Sheet during the LGM.