Kettle holes - stratigraphical archives for Weichselian geology and palaeoenvironment in northernmost Sweden

An active search for pre-Holocene organic deposits in stratigraphically well-defined positions has proved to be a useful tool for reconstruction of glacial and non-glacial Weichselian development in northernmost Sweden. The investigations have been concentrated to kettle holes connected to eskers belonging to a morphologically prominent northwesterly glacial system characterized by extensive drumlinization. Organic deposits, radiocarbon-dated as older than the Holocene, have been found at some 25 localities. Some sites display two organic-bearing sequences separated by a till bed. The pollen flora in the lowest organic bed reflects an interstadial vegetational development: Arctic shrub and herb tundra-subarctic light birch forestherb tundra with ericaceous shrubs and dwarf birch. This interstadial is correlated with Peräpohjola in Finland. During the younger Tärendö Interstadial the vegetational development was similar, but a more continental climate is indicated hy high values of steppe plants, e.g. Artemisia and Chenopodiaceae. The Tärendö Interstadial, correlated with Odderade, wascharacterized by open, unstable soils due to periglacial processes such as cryoturbation and eolian activities. The Weichselian glaciation is divided into three glacial stades separated by ice-free interstadials in the area studied. Except for a zone with S-SW drumlinization the impact of the two later ice sheets is insignificant.