ALLEROD, YOUNGER DRYAS AND EARLY HOLOCENE PALAEO-ENVIRONMENTAL STRATIGRAPHY

Investigation of the Polovecko-Kupanskoye pear bog, Yaroslavl District , central Russia, has revealed the sequence of Allerod, Younger Dryas, and Early Holocene palaeo-environmental events. Palynological assembl ages of Allerod age are dominated by spruce, with associated dwarf bir ch and cold steppe elements, suggesting widespread taiga forests. The transition to colder Younger Dryas conditions is marked by an abrupt d ecline of spruce, accompanied by sharp increases of Chenopodiaceae and Artemisia, and a lesser increase of Betula nana. Cold, dry steppe con ditions dominated during this phase. The onset of the Holocene Pre-Bor eal phase is indicated by a rise in arboreal birch pollen, and is mark ed by an initial warm event (Polovetsk warming) followed by renewed co oling (Peryaslavl cooling). The onset of the Boreal phase, ca. 9500 BP , was marked by the development of arboreal birch-pine forests, indica tive of climate warming. Following the termination of the Boreal phase , ca. 8000 BP, climatic fluctuations continued throughout the remainde r of the Holocene. (C) 1997 INQUA/Elsevier Science Ltd.