Moräntäckta rullstensåsar i Västerbottens inland

Detta är en Kandidat-uppsats från Umeå universitet/Institutionen för ekologi, miljö och geovetenskap

Sammanfattning:

The purpose of this study was to map the distribution of till-covered eskers in the inland of Västerbotten County in northern Sweden. The top layers of big eskers along the valleys of Öre River, Ume River and Vindel River were investigated through shallow digging. Findings were investigated through field assessment and soil analysis and many locations with till-covered eskers have been identified in Västerbotten's inland in this survey. The till covering the eskers has probably been transported only short distances and has its origins in glacifluvial material. The pattern is not consistent and there are areas where till does not cover the eskers. This can be explained trough irregular till deposition or that the till has been washed away or alternatively that the upper layer that is interpreted as glacifluvial material actually is till that has only been transported for very short distances. The findings of till-covered eskers in Västerbotten means that the traditional view of the eskers originating from the last deglaciation (Weichsel 3) may need to be reviewed. Where overlaying till has been found on top of eskers it means that the eskers must have originated in an earlier glaciation than the last. Only one layer of till could be discerned on the eskers in the survey, so an explanation could be that the till formed during Weichsel 3 and that the eskers formed earlier by the deglaciation of Weichsel 2, but dating the layers in till-covered eskers is difficult. No transition zone between till-covered to not till-covered eskers was found in this study.

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