Paleoflood marks in sandur morphometry as the result of the glacier surge (NW Poland)

Abstract

In the Pomeranian marginal zone of the last Pleistocene glaciation specific morphometric features are found. They represent indicators of surging events affecting the individual outlet glacier lobes of the Scandinavian Ice Sheet margin. They are assumed to have been active during the climate warming of the Weichselian glaciation decay. Many tunnel valleys deep-rooted in the proximal slopes of the terminal moraine ridge with incised gorges and wide extramarginal sandur fans spread from the mouths to the forefield. The relatively low relief intensity factor, the fluvioglacial sediments covering distal slopes of the terminal moraines and ‘washed out’ older forms may be considered as indirect evidence of outburst floods caused by a re-canalization of the subglacial drainage system. The morphometry of the palaeochannels in the gorge profiles are used to calculate estimates of extreme discharges (c. 5 × 103–105m3s–1).