Late Pleistocene pollen flora with Larix from till-covered esker at Hietamäki, Ostrobothnia, western Finland

ERIKSSON, BRITA and KUJANSUU, RAIMO, 1994: Late Pleistocene pollen flora with Larix from till-covered esker at Hietamäki, Ostrobothnia, western Finland. Bull. Geol. Soc. Finland 66, Part 2, 53-66. A till-covered layer of clay, fine sand and organic-bearing silt was found at Hietamäki near Haapajärvi, Ostrobothnia (Pohjanmaa), western Finland. The organic-bearing silt layer is an infill sediment in a dead ice hollow within a glaciofluvial formation interpreted as an esker. The esker is covered by till, at the base of which is a layer or lense of clay 1.5 m thick. On the basis of pollen content, the layers of clay and organic-bearing silt were deposited during the Eemian interglacial stage. Pinus-Picea-Larix forests mixed with Betula and Alnus possibly represent aregressive phase of the late Eemian vegetational development, when thermophile trees had already withdrawn from the area.