Rapid sea level changes in the Southern Baltic during late glacial and Early Holocene

In the area of the southern Baltic Sea, the largest and most violent changes in water level took place in Late Glacial and Early Holocene, during the period between 13.0-8.5 ka BP. These changes depended on the varied glacio-isostatic movements between the northern and southern parts of the Baltic Sea, the glacio-eustatic increase in the ocean level and the closing or opening of the connection between the Baltic Sea basin with the ocean. During the Late Glacial and Early Holocene, the sea level changed within an amplitude as wide as 25-27 m. In some extreme cases, the sea level could have fallen at a rate of about 100-300 mm/a, the sea level rise rate reaching up to about 40-45 mm/a. In Late Glacial and Early Holocene, there were three transgressions: during 12.0-11.2, 11.0-10.3 (the Baltic Ice Lake) and 10.2-9.2 ka BP (the Yoldia Sea and the Ancylus Lake). There were also three regressions, setting on 11.2, 10.3 and 9.2 ka BP. During regressions, depending on the real drainage rate and the local gradient of the bottom inclination, the land possibly grew at a rate of 0.3 to 4 km per year. During transgressions, rate of shoreline migration could reach in some cases up to 150-200 m per year. These processes took place on the surface of the sea bottom currently located at the depth of c. 55 to 25 m below sea level and from 30 to 60 km away from the present-day southern coast of the Baltic Sea. Rapid changes of shoreline position are recorded in progradational barrier structures and in the erosion surfaces of the glacial till and glacio-marine clays.