Simulation of the Baltic Sea shorelines in Estonia and neighbouring areas

Glacial retreat and the resulting isostatic land uplift together with the eustatic rise of sea level have determined the shore displacement around the Baltic Sea. Periods of damming and changes in the Baltic Sea outlet complicated the shoreline displacement at the end of the Late Weichselian and at the beginning of the Holocene. In the frame of the present research a shoreline displacement database of the Baltic Ice Lake (10 300 14C BP), Ancylus Lake (9200 14C BP), and Litorina Sea (7000 14C BP) transgressional shorelines in Estonia, NW Latvia and NW Russia was compiled. Of the total 414 sites, comprised in the data set, 254 points come from Estonia, 110 points from the neighbouring areas of Russia and 50 from coastal NW Latvia. The data were interpolated to the linear surfaces using point kriging approach and after elimination of residuals higher than 0.4 m the isobases of the above-mentioned stages of the Baltic Sea were simulated. The reconstructed isobases show that shoreline tilting was steeper in the northwestern part of the studied area during the Baltic Ice Lake and Ancylus Lake stages; this can be partly explained by hinge-lines. The variability of the uplifted shoreline azimuth has increased towards modern time, being most changeable during the Litorina Sea. The uplift gradient direction was quite irregular during the Ancylus stage. The uplift gradient magnitude was highest in North Estonia and NW Latvia, especially during the Baltic Ice Lake stage, obviously caused by differences in tectonic activities. The obtained new data refer to fairly uneven and inconsistent uplift of Estonia during the early Holocene, caused partly by the tectonics, geological structure and hydro-isostasy.