The role of hydro-isostasy for Holocene sea-level changes in the British Isles

Abstract

The last deglaciation of the British ice sheet in combination with melting of more distant ice sheets gives the nearby region a complicated sea-level history, with post-glacial rebound occurring over Scotland and northern England, eustatic sea-level rise much further away, and more complex changes in the intermediate regions like southern England. At the glacial maximum, most of the present North Sea floor was above sea level, and it has subsequently been covered by water. In most previous sea-level calculations, the meltwater load has usually been modelled without allowing for the change in ocean shape as sea-level changes, and frequently without including spatial variability of the meltwater load. By assuming the shoreline was at its present position throughout the period of deglaciation of the Late Pleistocene ice sheets, the amount of tilting of the British Isles by the meltwater load is reduced, since such a model erroneously applies loads both to the east and west of the British Isles. A review of the various meltwater models is included and it is shown that errors in predictions of sea-level change of up to 10 m at 10 kyr B.P. are made along the east coast of England and along the coastlines on the southern edge of the North Sea. The most important effect of the meltwater load is to tilt the continent normal to the continental margin. This pattern is modified by the unloading brought about by glacial rebound of Scotland and the Norwegian coast, and the recent filling with water of the North Sea.