Blowout (geology)

Blowout (geology)

Blowouts are sandy depressions in a sand dune ecosystem (psammosere) caused by the removal of sediments by wind.

Blowouts occur in partially vegetated dunefields or sandhills. A blowout forms when a patch of protective vegetation is lost, allowing strong winds to "blow out" sand and form a depression. Although they generally remain small, blowouts can expand to kilometers in size and up to around 70m in depth. [Pound, R. and Clements, F.E. 1900. The phytogeography of Nebraska. 2d ed. Lincoln, 442 pp.] [Jungerius, P.D. and van der Meulen, F. 1989. The development of dune blowouts, as measured with erosion pins and sequential air photos. Catena 16(4-5):369-376.]

Causes of vegetation loss include extended droughts, fire (natural and anthropogenic) or, in extreme cases, trampling by humans, cattle, horses, etc. [Wang Shuai, Hasi Eerdun, Zhuang Yanmei and Zhang Ping. 2008. A study of blowouts in the Hulun Buir Sandy Grassland, Northeast China. In: Correa, A.C., Agnello, M.F., Todd, R. and Peterson, R. (ed). Water in the Arid and Semiarid Lands. Proceedings of the 2006 International Conference, 15-17 November 2006, Lubbock, Texas, ICASALS Publication 2008-1, pp. 191-199.] Fire is the most common cause, however. In time, succession will begin again as suitable seeds are blown in and pioneers become re-established. [Barbour, E.H. 1895. Report of the geologist: Soils. In: Furnas, R.T. (ed), Annual Report, Nebraska State Board of Agriculture for the year 1894, pp. 61-92.]

Coastal sand dunes are found just inland from a beach, and are formed as the wind blows dry sand inland beyond the beach. It follows that this can only happen when there is an area of reasonably flat land inland from the beach. In time, this rather inhospitable surface will be colonised by pioneer species. These species (e.g. marram grass) will stabilise the dunes and prevent them moving any more. The process of plant succession will eventually see these dunes converted to woodland (depending on the climate) and a mature soil will have formed. [Hugenholtz, C.H. and Wolfe, S.A. 2006. Morphodynamics and climate controls of two aeolian blowouts on the northern Great Plains, Canada. Earth Surface Processes and Landforms 31(12):1540-1557.]

Blowouts provide an important habitat for flora and fauna. [Rydberg, P.A. 1895. Flora of the sand hills of Nebraska. Contributions from the United States National Herbarium 3:133-203.]


ee Also

*Sand Hills (Nebraska)

External links

* [ The Bibliography of Aeolian Research (BAR)]

Wikimedia Foundation. 2010.

Игры ⚽ Нужен реферат?

Look at other dictionaries:

  • Blowout — or Blow Out may refer to: *Blowout (well drilling), a sudden release of oil and gas from a well *Blowout (geology), a sandy depression caused by the removal of sediment by wind * Blow Out , a 1981 film directed by Brian De Palma * Blow Out (TV… …   Wikipedia

  • Blowout (well drilling) — A blowout is the uncontrolled release of crude oil and/or natural gas from an oil well or gas well after pressure control systems have failed.[1] Prior to the advent of pressure control equipment in the 1920s, the uncontrolled release of oil and… …   Wikipedia

  • Geology of the Death Valley area — The exposed geology of the Death Valley area presents a diverse and complex story that includes at least 23 formations of sedimentary units, two major gaps in the geologic record called unconformities, and at least one distinct set of related… …   Wikipedia

  • Médanos (geology) — For other uses, see Médanos (disambiguation). Unvegetated Médanos de Coro in Estado Falcon, Venezuela …   Wikipedia

  • 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… …   Wikipedia

  • Dreikanter — A Dreikanter is a type of ventifact that typically forms in desert or periglacial environments due to the abrasive action of blowing sand.[1] Dreikanters exhibit a characteristic three faced pyramidal shape. The word Dreikanter is a German word… …   Wikipedia

  • Erg (landform) — For other uses, see Erg (disambiguation). Issaouane Erg, Algeria. (31°11 …   Wikipedia

  • Indiana Dunes State Park — Indiana Dunes Designation(s) State Park; National Natural Landmark Location Porter County, Indiana, USA Address 1600 N 25 E Chesterton, IN 46304 Nearest City Porter, Indiana …   Wikipedia

  • Oil gusher — An oil gusher (or just gusher ; also sometimes called a wild well ) is an uncapped oil well connected to a reservoir of petroleum oil that is under high pressure. The oil can shoot 200 feet (60 m) or higher into the air.… …   Wikipedia

  • Conasauga shale — Coordinates: 33°41′55.09″N 85°36′14.74″W / 33.6986361°N 85.6040944°W / 33.6986361; 85.6040944 The Conasauga Shale is a Cambri …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”