Strunkpass

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According to Meyer's Lexicon, a Strunkpass is “the lowest point of a mountain pass that separates two river areas ”. In German-speaking geology, the “Strunkpass” is also characterized by the much stronger “retrograde erosion” of one of two flowing waters if their sources are on opposite sides of a dividing land elevation.

Strunk passports, in English "Wind gaps", is available as a special geoarchives on many continents. Erosion processes of two rivers in a region can have led to relief developments in long geological processes that can be characterized morphologically as stump passes.

Upper reaches of the Afon Erch, Wales , Great Britain. In the back right the now dry, tapped river bed.

Genesis of trunk passports

Geological profile on the Alb eaves . Strunk passes to Lauchert and Fehla .

If the greater erosion capacity of a river on one side reduces the catchment area of the river on the other side, this ultimately leads to the river tapping on the other side. The tapped river is diverted (eg the " Feldbergdonau "), or it is shortened and loses at least part of its catchment area; in the latter case, water erosion takes place in the remaining valley from now on only through a smaller body of water.

Strunk passes in limestone mountains

If, such as For example, in the Swabian Alb , the Dinaric Alps or the Southern Limestone Alps, river tapping was accelerated by karstification , the valleys of the "decapitated" upper reaches of tapped rivers can even become dry valleys .

Swabian Alb

Nine (!) Strunk passports of the Swabian Alb .
"Beheaded" Colonel Lauchert . Valley of an Urlauchert that extends far beyond today's Albtrauf .

After the gradual lowering of the Upper Rhine Rift and, as a result, the tectonic uplift and tilting of the Jura panels , the relationship between the two river systems Rhine and Urdonau had fundamentally and permanently changed. With the formation of the Upper Rhine Rift and the Rhine in it, a deeper erosion base was created. As a result of more powerful, retrograde erosion , the Rhine and its tributaries enlarged their catchment areas to the detriment of the Danubian river system. The right tributaries of the Neckar leading to the Albtrauf - all tributaries of the Rhine - were consequently able to steadily erode the northern edge of the Jura plateau. As a result, the catchment area of ​​the Upper Danube on the entire north side of the Swabian Alb became smaller. In several cases, Danube tributaries have already been “tapped”. Even today this geologically long “battle for the watershed” continues in favor of the Rhenish river system. Some of these rivers were formerly in the Miocene and until the early Pleistocene powerful rivers that drained large areas of southwest Germany to the south. They originally drained into the barley sand channel and later into the developing Urdonau. Among other things, the following are beheaded today: The rivers Schmiecha , Urlauchert , Urfehla , Große Lauter and Ur-Lone (see the very small Lone today ). "The valleys with their wide valley floors spread out into the air."

Very young Strunkpass education

Rhenish tap of the Feldbergdonau (Wutach- Aitrach -Donau)

A prime example of a relatively young Strunk Pass was created by tapping the so-called Feldberg Danube near Blumberg in the late Pleistocene (only around 20,000 years ago). The downstream part of the former Feldbergdonautal is today a wide, flat dry valley between Blumberg and the recent Danube east of Geisingen . In this valley there is also a wetland and a meager trickle called Aitrach . The Feldbergdonau was beheaded by the Rhenish Wutach, which eroded exceptionally quickly . The Wutach at a distance of 1–2 km has deepened its river bed by now 165 m compared to the wide valley floor of the Aitrach.

Individual evidence

  1. ↑ Meyers Grosses Taschenlexikon, Mannheim 1990. The Duden defines "Strunk" a. a. as "a dry stump of a dead tree", Duden, German Universal Dictionary, 2nd completely revised edition, 1989
  2. ↑ River taps can also occur with other geomorphologies and for other causes
  3. ↑ Lehmann (1933)
  4. ^ Morawetz (1976)
  5. ↑ The steeper slope curve (slope inclination) of the much shorter Rhine route to the global erosion base sea level causes an even greater relief energy of receding erosion.
  6. ↑ Eberle (2007), pp. 68, 74; Geyer (1980), p. 54
  7. ↑ z. B. Ur- Eschach areas up to the Black Forest , Urlone areas up to the Heilbronn area
  8. ↑ The Ur-Schmiechatal (former main valley) was beheaded near Lautlingen- Ebingen; Also near today's Schmiecha origin, which lies on the Swabian Alb, another head was created on the “Stich”, Geyer (1980), p. 54
  9. ↑ Ufrecht (2006), p. 54f
  10. ↑ Abel 2003, p. 67
  11. ↑ Geyer (1980), p. 54

literature

  • Lehmann (1933), Lehmann, E., The Gottscheer Hochland, Basics of Regional Studies, Scientific Publications of the Museum for Regional Studies in Leipzig, Leipzig 1933
  • Wagner (1953), Wagner, G., Morphology and River History, Excursion to the Westalb, Z. dt. Geol. Ges., 105, Stuttgart 1953, pp. 295-299
  • Morawetz (1976), Morawetz, S., Taps in the Styrian Randgebirge and its surroundings, attempt at a systematics. Communications from the Natural Science Association for Styria, 106, Graz 1976, pp. 77–94,
  • Geyer (1980), Geyer, OF & Schneider, G., Westalb and Vorland between Reutlingen and Balingen (Black Jura, morphology, tectonics, seismicity) in: Jber Mitt. Oberrhein. geol. Ver. n. F. 62, Stuttgart 1980
  • Scheff (1983), Scheff, J. Karstung in the upper Laucherttal - attempt to date age, Laichinger Höhlenfreund, 18, Laichinger 1983, p. 99ff
  • Geyer (1986), Geyer & Gwinner (1986): Geyer, OF, Gwinner, MS, Geologie von Baden-Württemberg, 3rd edition, Stuttgart, 1986
  • German Stratigraphic Commission (STD 2002), see web links
  • Abel (2003), Abel, Thekla, Investigations into the genesis of the Malmkarst of the Middle Swabian Alb in the Quaternary and later Tertiary, TGA C67, Diss. 2003, University of Tübingen, Geo. Fac. 2003
  • Ufrecht (2006), Ufrecht, W., A sealed cave ruin stage on the Kuppenalb between Fehla and Lauchert (Zollernalbkreis, Swabian Alb), Laichinger Höhlenfreund, Laichingen 2006
  • Eberle (2007), Eberle, J .; Eitel, B .; Blümel, WD; Wittmann, S. Germany's South from the Middle Ages to the Present, Heidelberg, 2007
  • Geotopes in the administrative district of Tübingen (2007), State Institute for the Environment, Measurements and Nature Conservation, Baden-Württemberg. See web links
  • Geotopes in the four administrative districts of Baden-Württemberg, protected area directory, full texts, LfU, Baden-Württemberg, 2000, 2003, 2005, 2007. See web links

See also

Web links

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