Depression (geology)


Depression (geology)

A depression in geology is a landform sunken or depressed below the surrounding area. Depressions may be formed by various mechanisms.

Structural or tectonic related:

  • Structural basin: A circular, syncline-like depression; a region of tectonic downwarping (e.g., associated with a subduction zone and island arc);
  • Graben or rift valley: down dropped and typically linear depressions or basin created by rifting in a region under tensional tectonic forces.
  • Pull apart basin caused by offset in a strike slip or transform fault (example: the Dead Sea area).
  • Oceanic trench: a deep linear depression located in the ocean floor. Oceanic trenches are caused by the subduction (when one tectonic plate is pushed underneath another) of oceanic crust beneath either other oceanic crust or continental crust.

Sedimentary related:

Glaciation related:

  • A basin formed by glaciation - depressed by the weight of the ice sheet resulting in post-glacial rebound after the ice melts (the area adjacent to the ice sheet may be pulled down to create a peripheral depression.)[2]
  • Kettle: a shallow, sediment-filled body of water formed by melting glacial remnants in terminal moraine.[3]

Volcanism related:

  • Caldera: a volcanic depression resulting from collapse following a volcanic eruption.[4]
  • Pit crater: a volcanic depression smaller than a caldera formed by a sinking, or caving in, of the ground surface lying over a void.
  • Maar: a depression resulting from phreatomagmatic eruption or diatreme explosion.

Erosion related:

Impact related:

References

  1. ^ a b "Dictionary of Geologic Terms - B". geotech.org. http://www.geotech.org/survey/geotech/dictiona.html#sectB. Retrieved 2006-08-25. 
  2. ^ "Glossary of Important Terms in Glacial Geology - Peripheral Depression". Montana State University. 1999. http://gemini.oscs.montana.edu/~geol445/hyperglac/glossary.htm#peripheral. Retrieved 2006-08-25.  Cites American Geological Institute’s Glossary of Geology (3rd edition, revised in 1987).
  3. ^ "Dictionary of Geologic Terms - K". geotech.org. http://www.geotech.org/survey/geotech/dictiona.html#sectK. Retrieved 2006-08-26. 
  4. ^ "Dictionary of Geologic Terms - C". geotech.org. http://www.geotech.org/survey/geotech/dictiona.html#sectC. Retrieved 2006-08-25. 

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