Internal structure and significance of ice-marginal moraine in the Kebnekaise Mountains, northern Sweden

Despite a long history of glaciological research, the palaeo-environmental significance of moraine systems in the Kebnekaise Mountains, Sweden, has remained uncertain. These landforms offer the potential to elucidate glacier response prior to the period of direct monitoring and provide an insight into the ice-marginal processes operating at polythermal valley glaciers. This study set out to test existing interpretations of Scandinavian ice-marginal moraines, which invoke ice stagnation, pushing, stacking/dumping and push-deformation as important moraine forming processes. Moraines at Isfallsglaciären were investigated using ground-penetrating radar to document the internal structural characteristics of the landform assemblage. Radar surveys revealed a range of substrate composition and reflectors, indicating a debris-ice interface and bounding surfaces within the moraine. The moraine is demonstrated to contain both ice-rich and debris-rich zones, reflecting a complex depositional history and a poly-genetic origin. As a consequence of glacier overriding, the morphology of these landforms provides a misleading indicator of glacial history. Traditional geochronological methods are unlikely to be effective on this type of land-form as the fresh surface may post-date the formation of the landform following reoccupation of the moraine rampart by the glacier. This research highlights that the interpretation of geochronological data sets from similar moraine systems should be undertaken with caution.