Main location (geosciences)

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The main layer (abbr. LH ) is mostly the youngest and thus the topmost of the periglacial layers . It was created towards the end of the last glacial period and consists essentially of components of the rock , loess and occasionally traces of the tephra of the Laacher See . The main location has an almost extensive distribution on the slopes of the low mountain range far into the basin areas, as far as they are not in the course of human intervention, e.g. B. by agriculture , was removed. The main layer appears in the pedological literature under different names, for example according to Semmel (1990) as cover debris , if the stone content is low as cover sediment .

Characteristics of the main layer are loose storage and a fairly constant thickness of 50 ± 20 cm. Main sites were found in various low mountain ranges under bogs , which is why their cold-age formation is certain, although their storage is disturbed by later events in many places due to fallen trees, forestry, etc., so that their formation by gelifluction is often no longer certain on the basis of the properties of the site itself can be proven.

An essential property of the main site, its very constant thickness, is hardly influenced by morphometric parameters such as slope inclination , exposure or location in the slope. Results of measurements of Durchtränkungsfließens suggest that a phenomenon can as the main location at Periglazialklima arise when several factors come together: The shift is short-lived, there is no fresh sediment, z. B. Aeolian , delivered later and there is no permafrost . The latter in particular is controversial in the literature on the main situation.

Due to its loose storage, the main location is the main root space of the vegetation . As mostly the top layer of the near-surface subsurface, it is particularly important for pedogenesis , as the A-horizons are developed in it. The loess content of the main layer usually has a positive effect on its buffer properties , which delays strong acidification for some time. The formation of the soils in individual cases does not only depend on the main layer itself, but also on which substrate follows below: If it is a central layer , a parabroun earth is very regularly developed, the Al horizon of which is found in the main layer. If a base layer with dense storage or a more densely compacted central layer follows below , a pseudogley can be formed in the case of a flat relief with the Sw horizon in the main position. Otherwise the development of a brown earth is to be expected with its Bv horizon in the main position. Podsols are rare and mostly a result of forestry use .

literature

  • A. Semmel: Periglacial morphology . Scientific Book Society, Darmstadt 1990, ISBN 3-534-01221-6 .
  • A. Semmel: Basics of soil geography . Teubner Study Books of Geography, Stuttgart 1993, ISBN 3-519-23408-4 .
  • Ad hoc working group Soil: Soil-Scientific Mapping Instructions . Ed .: Federal Institute for Geosciences and Raw Materials in cooperation with the State Geological Services, 5th edition, Hanover 2005. ISBN 3-510-95920-5 ( description of the contents of the Schweizerbart-Verlag )
  • A. Kleber: Geo-ecological importance of periglacial slope sediments . In: H. Gebhardt, R. Glaser, U. Radtke & P. ​​Reuber (Eds.): Geographie . Elsevier, Spektrum, Munich 2007 pp. 32–33, ISBN 3-827-41543-8 .
  • A. Kleber & J. Völkel: Slope sediments and their soils . In: German working group for geomorphology (Hrsg.): The earth surface. Space for people to live and create . Journal of Geomorphology NF Suppl.-Vol. 148, 2007, pp. 20-24.

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