The evolution of Lake Tänavjärv

The authors present the results of litho- and biostratigraphic investigation of L. Tänavjärv, NW Estonia. It has been found that the lake was isolated from the Litorina Sea at the end of the Late Atlantic period. Since then fine-grained sand and silt with plant macroremnants, diatomite and organic gyttja have been accumulated. On the ground of pollen and spore_ diagrams it is complicated to establish the limits of chronozones. The radiocarbon datings of Vaharu and Veski peatbogs are younger than it is assumed on the basis of biostratigraphic material. One reason for this may be the infiltration of ground water from the central part of raised bogs to their edge and into the lake. The neotectonic uplift also causes the changes in the ground water table and has a certain influence on this process. Since the end of the Late Atlantic period the aveiage uplift rate in this area is 2.1 mm per year.