Late Quaternary evolution of the Nysa Kłodzka river valley in the Sudetic Foreland, southwestern Poland

Abstract

The late Quaternary Nysa Kłodzka river terrace system has developed since the retreat of the Early Saalian (Odranian) ice sheet, which entirely covered the Sudetic Foreland and partly the Sudetes Mts. There are four terraces in the river valley, where the oldest one, the Upper Terrace, developed during and immediately after the ice sheet retreat, other terraces were deposited during the subsequent cold and warm stages, Wartanian, Weichselian and the Holocene. At the initial stage, the present river valley formed at the margin of retreating ice sheet. Later, the valley developed due to several erosion and sedimentation phases. The Nysa Kłodzka river flows through a zone of moderate to distinct tectonic activity, which is confirmed by seismic activity and recent crustal movements in the eastern part of the Sudetic Foreland. The neotectonic movements influenced much the evolution of morphology of this zone throughout the Quaternary and led to the shaping of the valley into its current form. During the late Quaternary, neotectonics could have been strenghten due to post-glacial isostatic rebound. These vertical movements disturbed the terrace system of the Nysa Kłodzka river valley, with the strongest terrace tilt in the Upper Terrace level, but less deflections visible even in the Holocene terrace levels.