Weichselian glacial stratigraphy in Hyvinkaa, southern Finland

Abstract

Two tills in Hyvinkaa represent one Weichselian glaciation: the lower till, named the Tanssikallio Till, being a basal lodgement till formed during the initial stage of the last Weichselian glaciation, and the upper till, named the Hyvinkaa Till, being a basal melt-out till from the time of the deglaciation of southern Finland, before the formation of the first Salpausselka marginal terrace. The tills can be compared with those earlier described from Kela west of Helsinki and from Vuosaari in Helsinki. The age of the lower basal lodgement till, when compared with the stratigraphy in Ostrobothnia, is not older than early Middle Weichselian. The possible ice-free interval between the deposition of the two tills at Vuosaari may correspond to the Middle Weichselian interstadial in Estonia. Elsewhere in southern Finland there is no conclusive stratigraphical evidence of an ice-free interval between an early Middle Weichselian and a Late Weichselian ice advance.