End moraine stratigraphy and formation in the southwestern Pyhä-Luosto fell area, northern Finland

The morphology, stratigraphy and composition of the small end moraine ridges were studied in the Pyhä-Luosto fell area, northern Finland. The ridges occur in a restricted area and are formed of unique formations, in groups of ridges with intervals of tens of metres, with the chains of ridges being several kilometres in length. The ridges are composed of two to three till units of which the middle one exhibits shear, thrust and push structures, and sandy or gravelly layers and lenses. Massive boulder-rich flow till units and stratified sediments relating to ice-marginal deposition are also observed. Based on the stratigraphical studies, the formation of the end moraines is due to oscillation of the ice margin in the supra-aquatic environment during the retreat phase of the Late Weichselian Ice Age. The end moraine ridge observations in the Pyhä-Luosto fell area are remarkable because these kinds of moraine deposits are rare in Finland, in the central part of the Last Scandinavian Ice Sheet.