Kick cart

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Step carts are second order cart structures . They arise from solution weathering on slightly inclined surfaces in karst rocks .

history

The term Trittkarre , engl. occurs barrow , barrow step or carting heelprint , was founded in 1960 by Alfred Bögli introduced. He used this to refer to step-like solution structures that cover rock surfaces that are gently sloping like stairs. E. and A. Chaix had already scientifically described this structure in 1907. Further editors were F. Bauer (1962), JN Jennings (1971), MM Sweeting (1972) and G. Soares de Carvalho (1975). A more recent work is by Márton Veress. The English term step karren goes back to F. Werner (1975), heelprint karren to A. Bögli (1980).

description

Secondary step carts formed on steep gully karst, karst of Italy

The height of each step usually varies between one and ten centimeters, with a maximum between three and five centimeters. They are arranged parallel to the height contours of the slightly sloping surface. The step width is between two and 25 centimeters, but in rare cases it can be up to a hundred centimeters. The steps that close the steps to the rear consist of a string of arched segments. Similar to an amphitheater, the rounded segments surround each individual step, which is preceded by a gently sloping, exposed ramp surface ( foreground ). As the angle of incidence of the surface increases, the tread width decreases and the steps consequently move closer together.

Varieties

The following varieties can be distinguished for step carts:

  • Embrionic step carts: They are much smaller than fully developed step carts. Their steps are usually much more curved and the steps are comparatively wider.
  • Niche carts : They have very wide steps with a low step. The individual stage elements coalesce and in extreme cases can form completely self-contained units which are then difficult to distinguish from real Kamenitzas.
  • Funnel carts : They consist of a funnel-shaped step, the step has been lost on them.
  • Uvala Trittkarren: With them, individual step segments merge with one another.
  • Rippelbarrow: Your steps are straight. So far they are only known in marble.
  • Step step carts: They are semicircular and develop near or on the edge of cleft carts and manholes.
  • Tetrahedron Carts: They only have steps and occur on very steep surfaces. It is quite possible that they are also a special form of pointed carts .

Occurrence

In addition to their widespread occurrence in limestone and dolomitic rocks , step carts made from marble and gypsum are also described. They can even be seen in sandstones .

Step carts are not only formed on free rock surfaces, they also arise on compensation areas , in gutter carts , on the ridge between individual gutters and even in larger Kamenitzas .

Haserodt (1965) found them at an altitude of 1900 to 2200 meters in the Alps.

Emergence

The trolleys parallel to the height contours lie transversely to the film of liquid sliding over the inclined surface. Its currents are undoubtedly responsible for the emergence of the step carts, but which factors determine the occurrence and the spatial arrangement of the step carts remains unclear. The decrease in the tread width with increasing angle of incidence indicates supercritical flows , characterized by the transverse ribs that arise in them .

Sinter terraces at hot springs have a very similar structure

See also

Individual evidence

  1. ^ Bögli, A .: Journal for Geomorphology . S2, 1960, p. 4-21 .
  2. ↑ Chaix, E. & Chaix, A .: Globe . tape 46 . Genève 1904, p. 17-53 .
  3. ↑ Jennings, JN: Karst . Massachusetts Institute of Technology Press, Cambridge, Massachusetts 1971.
  4. ^ Sweeting, MM: Karst Landforms . Macmillan, London 1972.
  5. ^ Lloyd, EF: NZ Geol. Surv. Bull. Band 85 , 1972.

literature

  • Allen, JRL: Sedimentary structures - their character and physical basis . 1984, ISBN 0-444-42232-3 .