Deglaciation pattern in sub‐aquatic — supra‐aquatic transitional environment illustrated by the klarälven valley system, värmland, western sweden

Abstract

The downwasting of the Weichselian ice sheet in the Klarälven valley and its continuation southwards has been studied. The meltwater drainage below the highest coastline (HCL) on the plain of Lake Vänern took place subglacially causing breaking‐up and calving around tunnel mouths in the ice margin. When the ice margin reached into the extension of the Klarälven valley, the drainage pattern changed to lateral. The ice disappeared as a narrow ice tongue later than in the surrounding highland. When the tongue receded northwards it left dead‐ice bodies behind, that remained in the valley after the general retreat. Along the tongue and dead‐ice bodies glaciofluvial sediments accumulated as kame terraces, deriving from esker trains in tributary valleys. At the mouths of the tributaries, deltas were deposited. Halts in the retreat occurred at a few places marked by thresholds of till. According to the present study the HCL rises northwards, from 180 m a.s.l. at Brattforsheden to 228 m at Höljes 170 km to the north. At halts in the ice recession it dropped a few metres. A tentative dating based on the level of the HCL, the tilt of raised shorelines and the rate of shoreline regression has given the time 10900 to 10360 calibrated years BP for the retreat of the ice margin from Brattforsheden to Höljes.