The importance of thermal boundary transitions on glacial geomorphology; mapping of ribbed/hummocky moraine and streamlined terrain from LiDAR, over Smaland, South Sweden

摘要

In this paper we synthesise previous sedimentological studies and new, high resolution, digital elevation models (DEMs) from southern Smaland to investigate the evolution of a deglacial landscape. Starting approximately at the deglacial highest shoreline, there is a 20-40-km-wide zone of ribbed and hummocky moraine that can be connected to the predominantly subaqueous Goteborg moraine. North of this there is a dramatic shift into streamlined terrain. Based on sedimentological investigations we conclude that these zones represent a sub/supraglacial stagnant-ice landsystem, followed by a subglacial active ice landsystem, which during their formations had very different thermal and process regimes along the ice-bed interface (freezing on/frozen versus wet-based basal regimes). New observations derived from high resolution, Light Detecting and Ranging DEMs reveal patterns of erosional/depositional and morphostratigraphic relationships that have not previously been observed, opening up gateways for future research.