Substratum morphology and significance during the Weichselian Odra ice lobe advance in northeast Germany and northwest Poland

Abstract

In the Polish Lowlands, three main ice lobes, referred to as Odra, Vistula and Mazury, formed during the Last Scandinavian Glaciation. These lobes protruded at least several kilometres beyond the main ice margin and it is believed that they represent terminal parts of the ice streams. Applied geostatistical analysis based on numerous geological data has allowed an approximate reconstruction of the Odra ice lobe substratum in the area of northwest Poland and northeast Germany. A spatial representation of the Odra lobe substratum clearly illustrates the adverse slope of the glacier bed, but also indicates areas morphologically prone to ice streaming. It is suggested that the ice took advantage of local topography that enabled advance out of the Baltic basin; consequently, the ice followed a topographic low which, in combination with favourable hydraulic conditions of its substratum, likely initiated ice streaming.

An erosional origin for drumlins of NW Poland

“…The pattern of SSBs in the Stargard drumlin field compared with the morphology of the land surface preceding the last ice advance reconstructed by Hermanowski (2015) (Figure 6A, B) suggests that the ice flow was to some extent topographically controlled. This pattern is consistent with findings elsewhere (Evans et al, 2008;Kessler et al, 2008;Ross et al, 2009;Winsborrow et al, 2010;Rignot et al, 2011;Margold et al, 2015;Fransner et al, 2017;Mulligan et al, 2019), although areas where bed topography exerted little influence on the ice flow are also known (Ross et al, 2009;Stokes et al, 2013b).…”

“…Engelhardt and Kamb, 1998;Breemer et al, 2002;Clarke, 2005;Lesemann et al, 2010a). The western part of Stargard drumlin field is underlain by glaciolacustrine silts and clays (Dobracka, 1981;Piotrowski, 1981;Hermanowski, 2015). With thickness between several and~40 m and spatial extent of more than 20 km, these deposits constitute a regional aquitard.…”

“…B. Distribution of streamlined subglacial bedforms in relation to the relief preceding the ice advance reconstructed by Hermanowski (2015). Isolines are in metres above the sea level.…”

“…Stargard drumlin field (Figure 1) is located in the eastern part of the Odra ice lobe marking a terminal part of a major palaeo-ice stream of the southern Scandinavian Ice Sheet (SIS) referred to as ice stream B 2 by Punkari (1997). The ice lobe protruded several tens of kilometres beyond the main ice sheet margin of the Pomeranian phase (approximately 16-17 ka BP; Marks, 2012;Rinterknecht et al, 2012) of the Weichselian glaciation and ice streaming was facilitated by inefficient drainage of subglacial meltwater Piotrowski et al, 2009;Hermanowski 2015). Stargard drumlin field was first described by Keilhack (1897), then by Karczewski (1976) and more recently by Piotrowski et al (2012).…”

“…Distribution of streamlined subglacial bedforms in relation to the relief preceding the ice advance reconstructed byHermanowski (2015). Zones comprising streamlined subglacial bedforms with common morphometric characteristics and orientations.…”