A 16 000-year record of near-field relative sea-level changes, northwest Scotland, United Kingdom

Abstract

Isolation basins, raised tidal marshes, coastal wetlands and dune systems around Arisaig in northwest Scotland produce a ∼16 000-year record of relative sea-level (RSL) change from the time of local deglaciation following the Last Glacial Maximum (LGM) to the present. New sea-level index points from Mointeach Mhor North define the culmination of the mid-Holocene RSL highstand to ∼7600–7400 cal yr BP and 6.74±0.2 m above present. Numerous sea-level index points indicate that the RSL highstand persisted more than 1000 years before the onset of any significant RSL fall. This points to a gradual cessation of melting of the Laurentide and Antarctic ice sheets, rather than an abrupt termination. Isolation basin evidence, from a marine limit ∼34 to 38 m above present down to sites close to current sea level, constrain the acceleration of eustatic sea-level rise during meltwater pulse 1a to ∼30 mm yr −1 or ∼11 km 3 yr −1 meltwater discharge. Comparison of RSL observations with glacial isostatic adjustment (GIA) model predictions show differences in the pattern of residuals dependent upon the GIA model used. Changes to the far-field ice model components can partly explain the patterns of residuals.