SEA LEVEL STUDIES | Eustatic Sea-Level Changes Since the Last Glaciation

Abstract

Eustatic sea-level changes, reflecting changing water volumes within ocean basins at a global scale, are registered along coastlines in a relative change in the height of the sea surface with respect to the land. Estimates from continental shelves in the far field of Pleistocene ice sheets suggest that sea level rose from c. −125 ± 5 m at 19 ka at the end of the Last Glacial Maximum and almost attained present levels by 7 ka. Far field locations record a stand of relative sea level higher than present as early as 7 ka ago, with a progressively falling sea surface since that time due to hydro-isostatic adjustments. The elevation and timing of the early Holocene highstand varies spatially and temporally. In near field areas in closer proximity to former ice sheets, an early Holocene sea level higher than present is not registered, apart from areas where the glacio-isostatic adjustment (uplift) following the withdrawal of ice sheets has far exceeded the rate of sea-level rise, resulting in an apparent relative fall in sea level. In other near field sites such as southern England, present sea level was only attained within the past 2 ka. It is likely that minimal deglaciation occurred in polar regions after 4 ka, thus permitting the formation of well-defined early Holocene highstands in far field locations.