Relict lateral moraines in northern Sweden—evidence for an early mountain centred ice sheet

Abstract

Glacial geomorphology along the eastern rim of the Scandinavian mountain range includes glacial landforms from the last deglaciation as well as from earlier glacial stages. One of the most prominent landform groups from earlier glacial stages, and the most diagnostic for ice sheet reconstruction, is a set of lateral moraines. In this paper, we describe these lateral moraines within a key area around Kvikkjokk, northern Sweden. Position of these lateral moraines in relation to the last deglaciation patterns indicates that they were formed before the last glacial maximum (LGM). The location and morphology of moraines show that they were deposited by a mountain centred ice sheet with outlet glaciers along major valleys, emanating from the highlands west of the Kvikkjokk area. This ice sheet was likely less than 170-km wide and no more than 600-m thick. Climatologically and glaciologically, we expect the relict lateral moraines to have been deposited before 75 ka BP (marine oxygen isotope stage 4). Their preservation is a consequence of subsequent overriding of nonerosive cold-based ice. Ice-marginal landforms and deposits from mountain centred ice sheet configurations in Fennoscandia are scarce. Therefore, the relict lateral moraines are important tools for reconstructing these elusive early glacial stages, possibly correlated to the ice sheet inception.