Holocene Sea Level changes, Cumberland Coast, Northwest England: Eustatic and glacio-isostatic movements

Abstract

Radiocarbon dates on materials from storm-eroded coastal sections plus other dates from peats and wood now below current high tide level are used to construct a preliminary history of relative sea level movement and to derive isostatic and eustatic components of the sea-level changes. Sea-level rose 22 m, relative to the land between 9,200 and 6,000 BP. No information is available for sea level between 6,000 and 3,600 BP but it was probably slightly higher than present. The main Postglacial Beach along this stretch of coast, and the highest evidence of marine action, is ca 5m above average high spring tide level. Shells in this beach date from 2,300±BP which suggests that at least storm waves were reaching these elevations 3,000 years or so after the usually accepted age for the feature. Relative sea-level changes after 3,600 BP were complex and there is at least one soil forming interval recorded. The high coastal sand dunes backing this stretch of coast date from between 1.200 and 1.500 BP. The estimated glacio-isostatic recovery is ca. 18m over the last 13,000 years. Computed eustatic curves indicate fluctuations in world sea-level in the last 5,000 years but these fluctuations could be caused by variations in storminess.