Late Holocene sea-level changes along the southern coast of Finland, Baltic Sea

Abstract

Lake isolation studies provide a reliable method for reconstructing the sea-level history of areas affected by the glacio-isostatic land uplift. In this study, Late Holocene relative sea-level changes were investigated along the southern coast of Finland, Gulf of Finland in the Baltic Sea, by studying 11 isolation basins in four areas (Kirkkonummi, Orslandet, Tenhola and Prästkulla), which extend across 120 km of Finnish coastline that is characterised by a narrow archipelago. The methods employed were lithostratigraphic interpretation, diatom analyses and radiocarbon dating. Also used in this work are the results from three previously studied isolation basins with four 14C dates. The sea-level history varies within the study area. The 3000 yr old Baltic Sea shoreline is located about 11 m above present sea-level (a.s.l.) in Prästkulla, and about 8 m a.s.l. in Kirkkonummi. These differences are due to the differences in isostatic uplift rates, which have been slower in the east. The main trend in relative sea-level along the southern coast of Finland is one characterised by a generally decreasing uplift rate during the Late Holocene. However, we identify the uplift anomalies in two areas where our data show phases of relative sea-level lowering. They are the first verified Late Holocene land uplift anomalies detected in Finnish sea-level data.