Contributions to the climate history from the late Highglacial to the early Holocene reconstructed by tree-rings and snail shells from several glaciations

All archives presented in this paper, with the possible exception of the Wylermoos (Belpberg), have been preserved due to the extreme geomorphic conditions at the time they were formed. In spite of the unfavourable ecological conditions at the time of the sedimentation of the loamy alluvia in the Daettnau valley near Winterthur, beneath the Uto at Zurich, and in the water meadows of the Reppisch near Birmensdorf as well as Landikon (all in Switzerland) these localities reflect the global changes at the transition from Highglacial to the early Holocene, in some cases involving several parameters. The tree-ring chronologies reveal the annual resolution of the Boelling and Alleroed as well as the calibration of the 14C-production rate. The high resoluted dendrochronological results are embedded in the stratigraphy of the accompanying mollusc and pollen records. The stable isotopes in the snail shells and lake marl deposits reflect the temperature development and reveal the correlation in the large area between Central Europe and Greenland. The stable isotopes in the fossil wood confirm the results from the mollusc records with reference to temperature and moisture conditions: During Boelling, the climatic conditions, in spite of some phases of inundations, were dryer and warmer than towards the end of the Alleroed. The warming from Oldest Dryas to Boelling, the climatic reverse into the Younger Dryas, and again the climatic improvement at the transition to the Preboreal proceeded abruptly. Evidence for this is provided by the trend of the δ18O-records and especially the tree-ring yields. Probable connection between the tree-ring chronologies and the LST-isochron within the varves opens new perspectives for correlations, and makes the datings more reliable. (author) 97 figs., tabs., 180 refs