A pollen analytical investigation supported by an 18O-record of a late glacial lake deposit at Grænge (Denmark)

Abstract

A core from a Late Glacial lake deposit at Graenge on the island of Lolland (Denmark) has been investigated with regard to the composition of the sediment, the palynology, including pollen concentrations and Betula pollen size measurements, and oxygen isotope composition of carbonate. It is concluded that the investigated part of the core covers the upper part of the Earlier Dryas, the Allerød, the Late Dryas, and the early part of the Holocene. Deposits of Earlier Dryas age were laid down subaerially. From the onset of the Allerød and afterwards a lake was present in which precipitation of calcium carbonate took place. The vegetational and oxygen isotope changes are related to changes in the environment. The early part of the Allerød possibly had the highest temperatures of this period but unstable, raw soil conditions and delayed immigration of tree-birch prevented an extensive growth of trees. During the middle part of the Allerød, soil conditions had improved and birch settled in the surroundings. During the Late Dryas the carbonate precipitation in the lake decreased to a minimum and tree-birch almost disappeared, suggesting that the temperature had dropped to, or below, the minimum temperature limit for this plant. The increase of temperature during the upper part of the Late Dryas seems to have taken place already before 10,000 B.P.