1516 K. Kaiser et al. Copyright © 2007 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms 32, 1516–1532 (2007) DOI: 10.1002/esp Earth Surface Processes and Landforms Earth Surf. Process. Landforms 32, 1516–1532 (2007) Published online 8 February 2007 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/esp.1480 Geomorphic evolution of small river–lake-systems in northeast Germany during the Late Quaternary Knut Kaiser, 1 Henrik Rother, 2 Sebastian Lorenz, 3 Peter Gärtner 4 and Ralf Papenroth 5 1 University of Marburg, Department of Geography, Deutschhausstrasse 10, 35032 Marburg, Germany 2 Institute for Environmental Research (ANSTO), PMB 1, Menai, NSW 2234, Australia 3 Consultants for Geology and Analytics (IHU), Tieplitzer Strasse 27, 18276 Gross Upahl, Germany 4 Barnim Nature Park, Wandlitzer Chaussee 55, 16321 Bernau, Germany 5 Consultants for Construction Materials and Environment (IBU), Berliner Strasse 2, 15566 Schöneiche, Germany Abstract This study investigates the post-glacial development of four small river–lake systems in the Weichselian belt of northern central Europe. The valleys investigated are part of an imma- ture drainage system characterized by frequent and abrupt changes in flow direction and the presence of numerous stagnant-ice depressions in the valley course. The depressions contain thick sedimentary sequences which provide excellent archives for the reconstruction of the post-glacial valley development. Study results indicate that the valleys reuse segments of former subglacial meltwater channels. During the Late Pleniglacial these channels carried meltwater streams. Stagnant-ice melting occurred in stages from the Oldest Dryas to the early Holocene and was often followed by the formation of lakes in the valley course. Flow reversals occurred during the Late-glacial–Holocene transition and were in response to general base-level lowering caused by stagnant-ice melting, headwater erosion and lake overspills. Lacustrine deposition typically started during the early Late-glacial comprising mainly silicate gyttjas, whereas organic gyttjas and peats accumulated during the Allerød. The Younger Dryas is associated with a marked increase in fluvial and aeolian sedimenta- tion, and lake-level high stands. This was followed by early Holocene lake-level low stands and a subsequent stabilization phase with decreasing silicate input and increasing organic lacustrine deposition. In general, dramatic changes in Late Pleniglacial to early Holocene sedimentation suggest that small-scale catastrophic events played a more important role in triggering geomorphic changes then previously recognized. Infilling continued until peat accumulation and terrestrialization of lake basins became widespread during the mid- to late Holocene. Beginning in the late Holocene anthropogenic influences become important mainly involving an increase in sediment supply due to forest clearing and land use, followed by mill stowage, river course correction and anthropogenic lake-level manipulations. Copyright © 2007 John Wiley & Sons, Ltd. Keywords: Late Weichselian; Holocene; post-glacial valley evolution; stagnant-ice depression Introduction Over the past two decades an increasing number of geoscientific and palaeoecological studies have aimed at resolving questions related to the Late Quaternary evolution of drainage patterns in central Europe (e.g. Hagedorn, 1995; Berglund et al., 1996; Mol et al., 2000). An important aspect of this work has been the high-resolution reconstruction of the impacts of past climate changes on river systems. In addition, much palaeoecological work has aimed at a better understanding of river floodplain, lake and bog ecosystems (e.g. Michaelis, 2002; Schönfelder and Steinberg, 2002). Geomorphologically, the investigations have focused on the study of the diverse interrelations between climate and the development of river systems (e.g. Vandenberghe, 2003). The state of knowledge on the Late Quaternary evolution of drainage patterns in central Europe varies substantially from region to region. A broad range of studies is available from the German uplands and Alpine forelands as well as from the Elsterian (c. >300 ka) and Saalian (c. >125 ka) glacial belts of northern Germany, The Netherlands and *Correspondence to: Knut Kaiser, University of Marburg, Department of Geography, Deutschhausstrasse 10, 35032 Marburg, Germany. E-mail: Knut.Kaiser@gmx.net Received 7 April 2006; Revised 3 November 2006; Accepted 16 November 2006