The marine Eemian of the Baltic: new pollen and diatom data from Peski, Russia, and Põhja‐Uhtju, Estonia

Abstract

AbstractSeveral relatively well‐preserved last interglacial (Eemian, marine oxygen isotope substage 5e; ca. 130–116 ka) deposits containing marine diatom flora have been found in Finland. In addition to these Finnish sites, more numerous Eemian (Mikulino) marine deposits are known from the northwestern part of Russia and from Estonia.Two new clayey and silty deposits covered by till, one at Peski, Russia, and the other Põhja‐Uhtju, Estonia, were studied for pollen and diatom content. At Peski, the deposit representing the Eemian interglacial is 3.8 m thick. The polyhalobous diatom flora in the Corylus and Carpinus zones indicates the maximum of the marine transgression during the climatic optimum. Later, the increasing proportion of brackish water diatom flora indicates a lowering in the relative sea‐level, and finally, during a very late phase of the Eemian, the sharply increasing proportion of freshwater species indicates the isolation of the sedimentary basin from the Eemian Sea.At Põhja‐Uhtju, according to the pollen, the Eemian deposit is 3.5 m thick. Diatoms occur only in a layer 1.6 m thick, which represents the period of Corylus and Carpinus zones, and thus the period of the climatic optimum. The brackish–marine diatom flora consists mainly of littoral, shallow‐water species.Although Peski is situated at a higher altitude than Põhja‐Uhtju at present, the diatom stratigraphy at Peski indicates deeper and more saline conditions than at Põhja‐Uhtju during the Eemian. This probably is the result of variations in glacio‐isostatic rebound between these sites, which can be accounted for by differences of the ice load during the final phase of the Saalian glaciation. Copyright © 2002 John Wiley & Sons, Ltd.