The Allerød/Younger Dryas transition in Wolin Island, northwest Poland, as reflected by pollen, macrofossils, and chemical content of an organic layer separating two aeolian series

Abstract

A palaeoecological study including pollen, macrofossils, and chemical analyses of an organic sediment separating two series of aeolian cover sands has enabled us to reconstruct environmental changes during the Allerod/Younger Dryas transition in Wolin Island, northwest Poland. The Allerod woodland dominated by Pinus sylvestris became more open at the beginning of the Younger Dryas, when aeolian (wind) activity resulted in instability of the soil. During the early phase of the Younger Dryas the water level in the local basin distinctly raised, indicating a change to a wetter climate. This short-lasting phase was followed by an increased frequency and intensity of aeolian processes. However, the main aeolian event took place before the major expansion of Juniperus, not later than 10,780±120 b.p. Frequent woodland fires, probably due to the activities of Palaeolithic people, have been documented both for the Allerod and the Younger Dryas periods. Macrofossils of Alnus sp. found in the Allerod layer are of special interest in showing the presence of alder trees in northwest Poland as early as the Late-glacial.