New age constraints for the maximum extent of the last British-Irish Ice Sheet (NW sector)

This paper presents the first terrestrial age constraints from the outer continental shelf for the maximum extent of the NW sector of the last British–Irish Ice Sheet. Cosmogenic 10Be ages from eight glacially transported boulders on the island of North Rona show that the Late Devensian (Late Weichselian) British–Irish Ice Sheet overrode the island at its maximal stage and retreated c. 25 ka BP. These new dates, supported by other geological evidence, indicate that the north-western part of the ice sheet was most extensive between 27 and 25 ka BP, reaching the outer continental shelf during the global eustatic sea-level minimum at the Last Glacial Maximum.