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

Abstract

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possibly represent a regressive phase of the late Eemian vegetational development, when thermophile trees had already withdrawn from the area.

Keywords

• stratigraphy
• till-covered esker
• organic-bearing silt
• pollen analysis
• correlations
• interglacial environment
• Eemian
• Weichselian
• Haapavesi
• Ostrobothnia
• western Finland