Sedimentation and lithostratigraphy of the Vuosaari multiple till sequence in Helsinki, southern Finland

Abstract

A multiple till sequence interbedded with sorted sediments has been investigated at Vuosaari, Helsinki, Finland. The investigation was carried out using standard sedimentological procedures combined with microfossil analysis in order to determine the genesis of the exposed sediments. This evidence is used to correlate lithostratigraphically the sequence with adjacent multiple till sequences in other parts of southern Finland (south of the Salpausselkä zone). It is concluded that all three till beds at Vuosaari are of basal origin that were laid down by separate ice flow phases. In contrast two rhythmite beds between the tills are thought to have been deposited in open water. The sediments at Vuosaari may have been laid down during the Weichselian glaciation although it is also possible that the lowermost till bed represents Saalian till.

Keywords

• till
• lithostratigraphy
• pollen analysis
• diatom flora
• deposition
• correlation
• Pleistocene
• Vuosaari
• Helsinki
• Finland