Weichselian red tills in the Gardno Phase End Moraine (Dębina Cliff) – criteria for distinction, origin and stratigraphic position, and implications for the origin and course of the Baltic Ice Stream

Jaroslaw Jasiewicz

doi:10.3285/eg.56.4.04

Abstract

Abstract. The paper presents the results of investigations of red tills from the South Baltic Middle Sea-Coast recorded in cliff exposures of Gardno Phase End Moraine. Distinctive features of these tills are: high percentage of Aland granitoids and porphyries identified in the 16-32 mm fraction, and large amounts of non-carbonate rocks, mostly red feldspars in relation to quartz, in the sandy fractions of 0,5-0,8 mm and 2-4 mm. Based on structural-textural features, the red till has been classified as flow till of local origin. The ice dynamism during Gardno Phase can be correlated with the Young Baltic Advance and most probably with the Belt Sea advance. On the basis of the petrographic properties of the Gardno red till and the results of radiocarbon dating, a new hypothesis regarding the origin, chronology and rate of flow of the Baltic Ice Stream is developed.

Highlights

Red tills are a well-known phenomenon in northern Germany, and a significant criterion for establishing changes in the dynamics of ice sheets during individual glaciations
The available information on Weichselian red tills in northern Germany has been summarised by STEPHAN (1985), with further information given subsequent publications (STEPHAN 1987, 1998, 2001)
Weichselian red tills identified in the crosssection of the cliff of the Gardno Phase end moraine include flow tills that are connected with the advance of the Gardno ice sheet

Summary

Introduction

Red tills are a well-known phenomenon in northern Germany, and a significant criterion for establishing changes in the dynamics of ice sheets during individual glaciations. Their common feature is the dominance of rock derived from the eastern and mid Baltic regions. According to KABEL (1982) and EHLERS (1992), four till types are recognisable, based on dominant pebble composition as follows: tills containing abundant Devonian dolomites and intensively crushed Devonian siltstones, with a high percentage of Paleozoic limestone. The main aims of this paper are to describe the lithological properties of the red tills found at Dębina, indicate the criteria used in distinguishing them as a separate lithostratigraphic

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