INITIATION OF THE LAST GLACIATION IN NORTHERN EUROPE

The bio-and chronostratigraphy of the Eemian interglacial (marine isot ope substage 5e) and an Early Weichselian glaciation (5d-a) establishe d from representative and detailed sequences can be correlated with th e deep-sea oxygen isotope stratigraphy, ice-con data, sea-level fluctu ations and coupled ice sheet-climate models. Biostratigraphic sequence s from Fennoscandian key sections are correlated with reference sequen ces from Estonia and from sections located near or beyond the margins of the last glaciation. Organic sediments previously attributed to Ear ly and Middle Weichselian interstadial periods in Finland are argued t o be redeposited and mixed older (last interglacial) material. Pollen and diatom spectra of the undisturbed materials suggest that the Eemia n climatic optimum was followed by a continuously cooling climate and a regressive marine level. If only undisturbed sequences are considere d, the major climatic fluctuations of the Early Weichselian, apparent in Central and Western Europe. are not apparent in the sequences from the central part of the glaciated terrain. Instead, some sequences are truncated by sediments indicating approaching ice sheets soon after t he interglacial. This may imply that the ice sheet grew over Finland d uring the first Early Weichselian stadial. The preservation of the int erglacial beds and the lack of younger non-glacial sediments support t he interpretation that the area remained ice-covered until the final d eglaciation. During the Early Weichselian, the Norwegian coast was pro bably occasionally ice free, similar to the coastal zone of Greenland today. The authors' interpretation of the Fennoscandian organic deposi ts of the last glaciation may also explain similar observations from t he central parts of the Laurentide ice sheet. (C) 1998 Published by El sevier Science Ltd. All rights reserved.