Sources of loess material for deposits in Poland and parts of Central Europe: The lost Big River Janusz Badura a , Zdzis1aw Jary b, * , Ian Smalley c a Polish Geological Institute, National Research Institute, Lower Silesian Branch in Wroclaw, Al. Jaworowa 19, 50-122 Wroclaw, Poland b Department of Physical Geography, Institute of Geography and Regional Development, University of Wroclaw, Pl. Uniwersytecki 1, 50-137 Wroclaw, Poland c Giotto Loess Research Group, Geography Department, Leicester University, Leicester LE1 7RH, UK article info Article history: Available online 23 June 2012 abstract The classical research of Smalley and Leach, investigating the origin of silty material for loess, paid attention to its possible relationship with valleys of the major Central European rivers. In contrast to loess occurring adjacent to the rivers Rhine, Danube, or Dnieper, the origin of silty material in the Central European Highlands and to the Carpathians was not believed to be related to the river valleys, but rather to the extent of the Weichselian Glaciation. The sources of the silt were to be the periglacial deserts at the margins of ice sheets. However, the duration of the loess-forming processes significantly exceeded the time that the ice sheet resided on the Central European Lowlands. Investigations of Late Pleistocene localities in brown coal mines in Lusatia have shed new light on the locations from where the silty material was derived. Research in the Lusatian ice-marginal valley has documented the presence of a large river flowing through the area from Eemian to Late Pleniglacial times. As fluvial deposits now overlie fluvioglacial sediments of the Warthe Stage, a river flowed during post-glacial times through a depression constituted by the Wroc1aweMagdeburgeBremen ice-marginal valley. The deeply incised ice-marginal valley transformed into a fluvial tract. Analyses of sediments and landforms in Lusatia and western Silesia indicate that in Late Pleniglacial times, a radical change of the river network must have occurred in this area. The Odra River, which had earlier headed to the North Sea, was captured by a glacial river flowing in new-formed BarutheG1ogów ice-marginal valley during the Leszno/Brandenburg Phase of the Last Glaciation. At the end of the Last Glacial, the Odra diverted to the north and eventually flowed to the Baltic Sea. The change in the course of the major river caused its tributaries coming from the mountains to bury its former valley with sediments. Deposition of eroded and weathered material took place in the Great Odra Valley under highly changing climatic conditions. Under periglacial conditions, this dry fine- grained material was eroded, transported, and deposited on the areas in front of the mountains, forming the Northern Loess Belt. Its alimentation area was thus the valley of one of the longest European rivers, active from the Warthe Stage until the Late Pleniglacial times (MIS 2e6), and not only a periglacial desert at the foreland to the Last Glacial Maximum (LGM). Ó 2012 Elsevier Ltd and INQUA. All rights reserved. 1. Introduction There are considerable deposits of loess in southern Poland. These are associated with the Carpathian and Sudetes mountains to the south, with the Pleistocene glaciations of northern Poland which reached the mountain foothills, and with the rivers Odra and Wis1a, which flow generally in a northerly direction towards the Baltic Sea. This paper is essentially concerned with the origins of loess material to form these deposits, but as this has wider impli- cations, it is necessary to consider the general problem of the source and distribution of loess material in East and Central Europe. In this way, the study extends and develops the review of loess in east and central Europe given earlier by Smalley and Leach (1978). Much revision is now required to the review by Smalley and Leach (1978). It was compiled a long time ago and much has changed in the interim. Smalley and Leach were concerned with the northern glaciers as producers of loess material and this may have distorted their view of the more southern parts of East and Central Europe. Certainly they rather neglected the Carpathian and Sudetes mountains as a source of loess material, and in the study of loess in Poland these mountains must loom large. Also there is a time factor; Smalley and Leach were essentially looking at relatively young loess and there is profit in looking at the older loesses in the region and considering their particular origins. * Corresponding author. E-mail addresses: janusz.badura@pgi.gov.pl (J. Badura), zdzislaw.jary@ uni.wroc.pl, zdzislaw.jary@gmail.com (Z. Jary), ijs4@le.ac.uk (I. Smalley). Contents lists available at SciVerse ScienceDirect Quaternary International journal homepage: www.elsevier.com/locate/quaint 1040-6182/$ e see front matter Ó 2012 Elsevier Ltd and INQUA. All rights reserved. http://dx.doi.org/10.1016/j.quaint.2012.06.019 Quaternary International 296 (2013) 15e22