by a sharp mountain front made up of an escarpment linked to the Sudetic Marginal Fault. Near Kaczawa this escarpment reaches 80 to 120 m in height. The relative influence of Pliocene-Quaternary tectonic movements and erosion in shaping the mountain landscape may vary along the northern front of the Sudetes. During the Quaternary glaciations the Giant 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. Mass wasting Other than debris flows there is little contemporary mass wasting in the mountains. Avalanches are common in the Sudetes. History The area around the Sudetes had by the 12th century been relatively densely settled with agriculture and settlements expanding further in the High Middle Ages from the 13th century onward. The majority of settlers were Germans from neighbouring Silesia, founding typical Waldhufendörfer. As this trend went on thinning of forest and deforestation had turned clearly unsustainable by the 14th century. In the 15th and 16th centuries agriculture had reached the inner part of Table Mountains in the Central Sudetes. Destruction and degradation of the Sudetes forest peaked in the 16th and 17th centuries with demand of firewood coming from glasshouses that operated through the area in the early modern period. Some limited form of forest management begun in the 18th century while in the industrial age demand for firewood was sustained by metallurgic industries in the settlements and cities around the mountains. In the 19th century the Central Sudetes had an economic boom with sandstone quarrying and a flourishing tourism industry centered on the natural scenery. Despite this there was at least since the 1880s a trend of depopulation of villages and hamlets which continued into the 20th century. Since World War II various areas that were cleared of forest have been re-naturalized. Industrial activity across Europe has caused considerable damage to the forests as acid rain and heavy metals has arrived with westerly and southwesterly winds. Silver firs have proven particularly