Distribution and glaciological implications of relict surfaces on the Ultevis plateau, northwestern Sweden

Abstract

AbstractThe Ultevis plateau, northwestern Sweden, has a relief of less than 200 m, yet bears three different kinds of landscape, classified according to the degree of glacial erosion. The first type is restricted mainly to topographic highs and has almost entirely escaped erosion, despite complete and prolonged ice cover during the late Weichselian. The other two landscape types are distinguished depending on whether older land- forms have been completely erased or not. The latter two appear to have undergone erosion only briefly. The transitions between landscape zones are usually sharp, and specific boundary landforms occur. The Scandinavian ice sheet was cold-based in its central areas during its maximum. During the deglaciation, both the dry/wet-base boundary and ice margin migrated inwards, at different speeds. When the ice front retreated faster than the thermal transition zone, the wet-base marginal zone shrank and erosion was reduced or avoided. Where the wet-base zone was of limited longitudinal extent, as on the Ultevis plateau, conversion from a frozen to a thawed bed was incomplete, leaving a patchwork of preserved glacial and non-glacial morphologies.