AskDefine | Define Graben

User Contributed Dictionary

see graben

German

Etymology

Old High German grabo

Noun

  1. ditch
  2. trench

Extensive Definition

A graben is a depressed block of land bordered by parallel faults. Graben is German for ditch.
A graben is the result of a block of land being downthrown producing a valley with a distinct scarp on each side. Grabens often occur side-by-side with horsts. Horst and graben structures are indicative of tensional forces and crustal stretching. ''
Graben are produced from parallel normal faults, where the hanging wall is downthrown and the footwall is upthrown. The faults typically dip toward the center of the graben from both sides. Horsts are parallel blocks that remain between grabens, the bounding faults of a horst typically dip away from the center line of the horst.
A single graben or multiple grabens can produce a rift valley.

Half-grabens

In many rifts the grabens are asymmetric, with a major fault along only one of the boundaries, and these are known as half-grabens. The polarity (throw direction) of the main bounding faults typically alternate along the length of the rift. The asymmetry of a half-graben strongly affects syntectonic deposition. Comparatively little sediment enters the half-graben across the main bounding fault, due to the effects of footwall uplift on the drainage systems. The exception is at any major offset in the bounding fault, where a relay ramp may provide an important sediment input point. Most of the sediment will enter the half-graben down the unfaulted hanging wall side (e.g. Lake Baikal, ).

Famous grabens

See also

References

  • Physical Geography: A Landscape Appreciation
Graben in German: Graben (Geologie)
Graben in Estonian: Alang
Graben in Basque: Graben
Graben in French: Graben
Graben in Korean: 지구대
Graben in Italian: Graben (geologia)
Graben in Hebrew: גראבן
Graben in Dutch: Slenk (geologie)
Graben in Japanese: 地溝
Graben in Norwegian: Graben
Graben in Norwegian Nynorsk: Graben
Graben in Polish: Rów tektoniczny
Graben in Portuguese: Graben
Graben in Ukrainian: Грабен
Graben in Chinese: 地塹
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