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A review of Scottish marine shell radiocarbon dates, their standardization and interpretation

Synopsis A list of published marine shell radiocarbon dates is produced by applying a standard set of operations to the pretreatment and subsequent assessment of such dates. Marine shell dates, in general, when compared to other such dates in the same stratigraphic sequence, give results that are consistent with their stratigraphic relationships. Marine shells also give results that are comparable with dates obtained from terrestrial materials. The radiocarbon dates on ice-transported or over-ridden marine shells show a threefold division: ‘infinite’ dates that may relate to an Early Devensian ice sheet build-up; dates from the Middle/Late Devensian that indicate Late Devensian ice expansion in the Outer Hebrides; and dates from the Lateglacial related to the Loch Lomond Readvance. The many marine shell dates from the head of the Firth of Clyde and the Clyde estuary imply that the area around the mouths of the sea lochs was deglaciated by c. 13,000 yr BP and that there was an ice-free period in the inner sea lochs from at least c. 12,400 yr BP till at least c. 10,800 yr BP prior to the maximum of the Loch Lomond Readvance.