Rogen moraine:: an example of glacial reshaping of pre-existing landforms

Rogen moraine is widely distributed in the core areas of the former Scandinavian and Laurentide ice sheets. It is generally agreed upon that these gently arched, ice-How transverse ridges call be used in reconstructions of paleo-ice-flow patterns and that they indicate a melted-bed or poly-thermal basal ice regime. However, the processes of ridge generation have been contentious. This study proposes a two-stage formation of Rogen moraine, based oil detailed sedimentological and structural investigations in excavated trenches in a Ropen moraine landscape in the province of Dalama, central Sweden. Field data suggest that Rogen moraine ridges are the reshaped remains of pre-existing transverse moraine ridges, originally deposited from ice-cored moraines ill an ice-marginal zone. Due to back- and down-wasting of ice-cores, inter-ridge troughs were filled with debris flow and fluvial deposits, which after landscape inversion were transformed to areas of transverse and hummocky moraines. It is proposed that this primary landscape formation Occurred during an Early Weichselian deglaciation. This relict landscape was later preserved beneath cold-based Mid- to Late-Weichselian ice sheet(s), which turned wet-based during the Preboreal deglaciation phase and re-moulded the precursor landforms into Rogen moraine. (c) 2005 Elsevier Ltd. All rights reserved.