{{Short description|Glacial landscapes in Central Europe}} '''Old and Young Drift''' are geographic names given to the [[morainic]] landscapes that were formed in Central Europe; the Old Drift during the older [[ice age]]s and the Young Drift during the latest [[glaciation]]s – the [[Weichselian]] in North Germany and the [[Würm glaciation|Würm]] in the [[Alps]]. Their [[landform]]s are quite different. Areas of Old Drift have been heavily flattened and transformed as a result of geomorphic processes such as [[denudation]] and [[erosion]], whilst areas of Young Drift have largely retained their original shape. Whilst the majority of Old Drift moraines were formed during the [[Saale glaciation]] about 130,000 to 140,000 years ago, the Young Drift moraines in Central Europe are only about 15,000 to 20,000 years old. The terms Old and Young Drift are used for all elements of the [[glacial series]] even though the meltwater deposits and landforms are not strictly moraines.
== Old Drift == The Old Drift landscapes were [[tundra]]s or [[cold desert]]s during the last ice age. [[Periglacial]] processes resulted in significant [[ablation]] of higher terrain as well as [[Glacier ice accumulation|accumulation]] of [[Sedimentary rock|sediments]] in the depressions. As a result of that the old glacial forms have clearly been worn down. In addition almost all closed hollows (e. g. [[dead ice]] [[kettle hole]]s) have been completely filled in. Old Drift landscapes are therefore much less [[terrain|relief]]-intensive than Young Drift regions and have hardly any natural [[lake]]s. The [[river system]] of Old Drift areas is normal and hierarchical.
Due to advanced [[weathering]] of the sediments near the surface, the [[soil]]s are more heavily leached ( ([[Brunification|brunified]], [[decalcified]] and/or [[podsol]]ized). The [[glacial till]] is generally decalcified to 3–4 metres; thinner strata may be entirely decalcified. Very common are wind-formed ablation or accumulation landforms, because during the [[glacial period]]s, the wind could easily blow [[sand]] and [[silt]] away due to the lack of a layer of vegetation. The presence of [[ventifact]]s, [[dune]]s and [[loess]] is thus typical of Old Drift areas.
== Young Drift == Young Drift morainic landscapes by contrast have new landforms that are still recognisable as [[glacial]] forms. There are numerous enclosed hollows, many of which are filled with water. The river system is often still immature and rather chaotic. There are numerous inland drainage areas. [[Ventifact]]s and [[dunes]] do occur; but these landforms are much younger and less intensively formed than in Old Drift country. The soils are markedly less weathered than those of the Old Drift. On areas of [[ground moraine]], the depth of decalcification of the [[glacial till]] is thus often less than 1 metre.
== Literature == * {{citation|surname1=Frank Ahnert|title=Einführung in die Geomorphologie |edition=1st|publisher=Verlag Eugen Ulmer|publication-place=Stuttgart|pages=350 ff|isbn=3-8252-8103-5|date= 1996|language=German}}
== External links == *{{cite web |url=http://satgeo.zum.de/satgeo/beispiele/glossar/altmo.htm |title=Kleines Glossar zur Glazialmorphologie: Moränen: Jungmoräne, Altmoräne |publisher=Zentrale für Unterrichtsmedien im Internet e.V.|work=Satellitengeographie im Unterricht, Merzhausen |access-date=2009-12-10}}
[[Category:Glacial landforms]] [[Category:Geodynamics]]