Ephemeral
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{{Wiktionary|ephemeral}}
[[Image:MawsonPlateau-04.jpg|thumb|right|The epheremal nature of Granite Plateau Creek on the [[Mawson Plateau]], means the creek is usually a series of waterholes.]]
[[Image:2006-05-20 - Staircase Falls.jpg|thumb|right|Staircase Falls in [[Yosemite National Park]] only flows after heavy rainfall.]]
[[Image:Home reef.jpg|thumb|right|[[Home Reef]] has repeatedly breached the surface and been subsequently eroded by wave action.]]
'''Ephemeral''' things (from [[Greek language|Greek]] ''εφήμερος'' - ''ephemeros'', literally "lasting only one day"<ref>[http://www.perseus.tufts.edu/cgi-bin/ptext?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3D%2345743 Ephemeros], Henry George Liddell, Robert Scott, "A Greek-English Lexicon", at Perseus</ref>) are transitory, existing only briefly. Typically the term is used to describe objects found in nature, although it can describe a wide range of things.
==Geographical examples==
An ephemeral [[waterbody]] is a [[wetland]], [[Spring (hydrosphere)|spring]], [[stream]], [[river]], [[pond]] or [[lake]] that only exists for a short period following [[Precipitation (meteorology)|precipitation]] or [[snowmelt]]. They are not the same as intermittent or seasonal waterbodies, which exist for longer periods, but not all year round.
Examples of ephemeral streams are the [[Ugab River]] in [[Southern Africa]], and a number of small ephemeral [[watercourse]]s that drain [[Talak]] in northern [[Niger]]. Other notable ephemeral rivers include the [[Todd River]] and [[Sandover River]] in [[Central Australia]] as well as the [[Son River]], [[Batha River]] and the [[Trabancos River]].
[[Lake Carnegie (Western Australia)|Lake Carnegie]] in [[Western Australia]] and [[Lake Cowal]] in [[New South Wales]] are ephemeral lakes. Lake Tuzkan and [[Mystic Lake (California)|Mystic Lake]] in California are ephemeral.
There are also ephemeral islands such as [[Banua Wuhu]] and [[Home Reef]], which reappear and disappear beneath the waves.
==Biological examples==
Many plants are adapted to an [[Ephemeral plant|ephemeral lifestyle]], in which they spend most of the year or longer as seeds before conditions are right for a brief period of growth and reproduction. The spring ephemeral plant [[mouse-ear cress]] is a well known example. Animals can be ephemeral, with [[brine shrimp]] being an example.
==Ephemeral artifacts==
Ephemeral can also be used as an adjective to refer to a fast-deteriorating importance or temporary nature of an object to a person. [[Brands]] are notoriously ephemeral assets, and [[magazine]] publishing was once much more ephemeral than it is today.
A number of art forms can be considered ephemeral because of their temporary nature. Early [[land art]] and all [[sand sculpture]]s, [[ice sculpture]]s and chalk drawings on footpaths are examples of ephemeral art. [[G. Augustine Lynas]] and [[Duthain Dealbh]] create ephemeral sculptures.
==Other uses==
The [[placenta]] is considered an ephemeral [[organ (anatomy)|organ]] present during [[gestation]] and [[pregnancy]].
A sensation which is felt by a person for a certain period of time before needing replenishment can be referred to as ephemeral. Often, happiness is described as ephemeral, as one does not find it as a permanent state, with human lives always varying shades of happiness and disappointment.
==References==
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{{geology-stub}}
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[[Category:Rivers]]
[[Category:Lakes]]
[[Category:Greek loanwords]]
[[cs:Efeméra (rostlina)]]
[[de:Ephemere]]
[[lt:Efemerai]]
[[pt:Efémero]]
[[sk:Efeméra (rastlina)]]