A relative sea-level curve for the Polish Southern Baltic Sea

The relative sea-level curve was developed for the southern Baltic area, based on a set of 315 radiocarbon dates of different terrestrial and marine sediments, collected at 164 sites located in the Polish part of the Southern Baltic and in the adjacent coastal land area. When developing the curve, relicts of various formations related to the shoreline evolution as well as extents of erosional surfaces, determined from seismoacoustic profiles, were taken into account. During the Late Pleistocene and Early Holocene, i.e., between 13.0 and 8.5 ka BP, the southern Baltic sea level rose and fell three times, the amplitude of changes extending over 25–27 m. In the Late Boreal, c. 8.5 ka BP, the Baltic—its water level by about 28 m lower than the present one—became permanently connected with the ocean. Until the onset of the Atlantic, the sea level had risen to about 21 m below present sea level. During 8.0–7.0 ka BP, the sea level was rising, to reach −10 m. Subsequently during the Atlantic, until its end, the sea level rose to 2.5 m b.s.l. During the first millenium of the Subboreal, the sea level rose to about 1.3–1.1 m b.s.l., to become—on termination of the Subboreal—about 0.7–0.6 m lower than present. During the Subatlantic, the sea-level changes were minor.