Periglacial Geomorphology

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Many present landscape elements in western and central Europe are to a large extent the result of periglacial processes that prevailed during cold periods more than 10,000 years ago. As with the glacial chapter, this account of the periglacial geomorphology also needs to base itself upon processes that no longer or only to a limited extent take place in the areas today. Consequently, this chapter will include an overview of some of the most important periglacial processes and deposits and their effects upon landscape development as influenced by variations in periglacial environmental conditions, lithology, and vegetation cover. Most landscapes that were glaciated during the Weichselian have accentuated relief, especially where subsequent human modification has been relatively modest. It is probable that the glaciated parts of Europe were also accentuated after the Saalian glaciation, but today smooth surfaces and gentle slopes characterize the Saalian areas. During interglacial periods relatively little landscape modification has taken place, and the difference in morphology between the Weichselian glacial landscape and the areas beyond is mainly due to the activity of periglacial processes. As a consequence these European landscapes can be regarded as periglacial. Even where a periglacial overprinting can be strongly demonstrated in the geomorphology of many western European landscapes the expression ‘periglacial landscape’ has not been widely used. There may be two main reasons for this. First, even if landforms resulting from periglacial processes may be geographically widespread, they are not normally as eye-catching and morphologically diverse on a local scale as are those resulting from glacial activity. Secondly, it is difficult to geographically delimit a periglacial area: in relation to a glaciated area where the criterion is whether the ice was there or not, the delineation of a periglacial area is dependent on much more subtle features and arbitrary criteria. Further, landscapes that show general imprints of past periglacial conditions often contain areas that bear identifiable imprints of the dominant activity of a single agent, such as water, wind, or gravity. Even if some of these activities may be particularly efficient in cold climates, they are nevertheless of a wider occurrence.