Palaeosols as Quaternary stratigraphic key horizons in Ostrobothnia, western Finland

KUJANSUU, RAIMO, 1992. Palaeosols as Quaternary stratigraphic key horizons in Ostrobothnia, western Finland. Bull. Geol. Soc. Finland 64, Pari 2, 161—167. In Ostrobothnia, western Finland, palaeosols have been recognized at several sites in the sandy deposits between glaciofluvial sediments and the overlying till. The palaeosols resemble postglacial podzol. As climatic conditions changed, the palaeosols at Kärjenkoski, Risåsen and Norinkylä were gradually covered with sand transported by the wind and rainwater, and the A horizons grew in thickness. Under early-glacial conditions the podzol was buried under proglacial sands, which, despite often being deformed by the advancing ice sheet, also contributed to the preservation of the palaeosols. According to TL and OSL dating, the palaeosols were formed 164—83 ka ago, implying that the ice-free period in southern Ostrobothnia lasted from the Saalian deglaciation to the end of the Br0rup interstade or even to the beginning of the MidWeichselian. Palaeosols can be used as stratigraphic key horizons to correlate systems over large areas.