During the Quaternary glaciations the Krkonoše mountains was the most glaciated part of the Sudetes. Evidence of this are its glacial cirques and the glacial valleys that develop next to it. The precise timing of the glaciations in the Sudetes is poorly constrained. Parts of the Sudetes remained free from glacier ice developing permafrost soils and periglacial landforms such as rock glaciers, nivation hollows, patterned ground, blockfields, solifluction landforms, blockstreams, tors and cryoplanation terraces. The occurrence or not of these periglacial landforms depends on altitude, the steepness and direction of slopes and the underlying rock type.