CLIMATIC OSCILLATIONS OF THE MAZOVIAN (HOXNIAN) INTERGLACIAL IN THE POLLEN AND ISOTOPIC RECORDS. J. Nitychoruk, K. Binka, M. Chodyka, H. Ruppert, A.Tudryn. Department of Geology, Pope John Paul II State School of Higher Education in Biala Podlaska ul. Sidorska 95/97, 21-500, Biafa Podlaska E-mail: jerzy.nitychoruk@pswbp.pl, m.chodyka@dydaktyka.pswbp.pl department of Paleontology, Institute of Geology, University of Warsaw, Al. Zwirki I Wigury 93, 02-089 Warszawa E-mail: k.binka@uw.edu.pl. Department of Sedimentology, Geowissenschaftliches Zentrum der Universitaet Goettingen (GZG) Goldschmidt str. 1-3, 37077, Goettingen, Germany E-mail: hrupper@gwdg.de. Faculte des Sciences d’Orsay, University de Paris XI, Campus universitaire d’Orsay – 91 405, Orsay Cedex, France E-mail: alina.tudryn@u-psud.fr.

The evolution of plant assemblages during the Mazovian (Hoxnian) Interglacial is intermitted by several changes of the vegetation cover that can be observed in pollen diagrams from entire Europe. Two periods of larger-scale climatic oscillations have been noted during this interglacial; they caused vegetation changes and modification in the values of oxygen and carbon isotopes. The first climatic change occurred after the maximal content of yew (Taxus) and was caused by cooling comparable to that from 8.2 ka ago in the Holocene, resulting from oscillations of the North Atlantic circulation. The second oscillation took place during the climatic optimum of the interglacial and is reflected in Western Europe in changes of tree stands – disappearance of hornbeam and partly spruce in favour of birch and pine. In the Osscwka profile, southern Podlasie, Poland, this interval is marked by the disappearance of spruce and culmination of hornbeam, whereas increased concentration of heavy isotopes of oxygen and carbon is observed in the lake basin. The accompanying increase of volcanic ash concentration in deposits allows correlating climatic changes with volcanic activity.