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Created page with 'File:lighterstill.jpgright|frame ==Origin== classical Latin ''Oasis'', the name of a fertile place in the Libyan desert < ancient [...'
[[File:lighterstill.jpg]][[File:Huacachina-oasis.jpg|right|frame]]

==Origin==
classical Latin ''Oasis'', the [[name]] of a [[fertile]] place in the Libyan [[desert]] < ancient [[Greek]] ''Ὄασις'' (Herodotus; compare Hellenistic Greek ''Αὔσις'' (Strabo)) < ancient Egyptian ''wḫ'-ṭ''; compare Coptic ''ouahe'' dwelling-place
*[http://en.wikipedia.org/wiki/17th_century 1613]
==Definitions==
*1: a [[fertile]] or green area in an arid region (as a [[desert]])
*2: something that provides refuge, relief, or pleasant [[contrast]]
==Description==
In [[geography]], an '''oasis''' (plural: oases) or [http://en.wikipedia.org/wiki/Cienega cienega] (Southwestern United States) is an isolated area of [[vegetation]] in a [[desert]], typically surrounding a spring or similar [[water]] source. Oases also provide [[habitat]] for animals and even [[humans]] if the area is big enough.

The location of oases has been of critical importance for [[trade]] and [[transportation]] routes in [[desert]] areas. [[Caravan]]s must travel via oases so that supplies of [[water]] and [[food]] can be replenished. Thus, [[political]] or [[military]] [[control]] of an oasis has in many cases meant control of [[trade]] on a particular route. For example, the oases of [http://en.wikipedia.org/wiki/Awjila Awjila], [http://en.wikipedia.org/wiki/Ghadames Ghadames] and [http://en.wikipedia.org/wiki/Kufra Kufra], situated in [[modern]]-day Libya, have at various times been [[vital]] to both North-South and East-West [http://en.wikipedia.org/wiki/Trans-Saharan_trade trade in the Sahara].

Oases are formed from underground [[rivers]] or aquifers such as an [http://en.wikipedia.org/wiki/Artesian_aquifer artesian aquifer], where [[water]] can reach the [[surface]] naturally by [[pressure]] or by man made [[wells]]. Occasional brief thunderstorms provide subterranean water to sustain [[natural]] oases, such as the [http://en.wikipedia.org/wiki/Tuat Tuat]. Substrata of impermeable rock and stone can trap water and retain it in pockets; or on long faulting subsurface ridges or volcanic dikes water can collect and percolate to the [[surface]]. Any incidence of water is then used by [[migrating]] birds who also pass [[seeds]] with their droppings which will grow at the water's edge forming an oasis.

[[Category: Geography]]

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