Editing Geyser (section)

{{Short description|Natural explosive eruption of hot water}}
{{About|volcanic geysers|{{CO2}}-driven geysers|Cold-water geyser|other uses}}
{{Use Oxford spelling|date=October 2024}}
{{Use dmy dates|date=October 2024}}

[[File:Yellowstone National Park (WY, USA), Old Faithful Geyser -- 2022 -- 2599.jpg|thumb|upright=1.3|alt=Water ejecting from the ground and steam rising to the right|[[Old Faithful]] erupting at [[Yellowstone National Park]]]]

A '''geyser''' ({{IPAc-en|ˈ|g|aɪ|z|ər}}, {{IPAc-en|uk|ˈ|g|iː|z|ər}})<ref>{{cite web |url=http://dictionary.cambridge.org/dictionary/british/geyser?q=geyser |title=Definition of geyser noun from Cambridge Dictionary Online |access-date=9 July 2011}}</ref><ref>{{Cite web |url=http://www.oxforddictionaries.com/definition/english/geyser |archive-url=https://web.archive.org/web/20130609235600/http://oxforddictionaries.com/definition/english/geyser |url-status=dead |archive-date=9 June 2013 |title=geyser {{!}} Definition of geyser in English by Oxford Dictionaries |website=Oxford Dictionaries {{!}} English}}</ref> is a [[spring (hydrosphere)|spring]] with an intermittent water discharge ejected turbulently and accompanied by steam. The formation of geysers is fairly rare and is caused by particular [[hydrogeological]] conditions that exist only in a few places on Earth.

Generally, geyser field sites are located near active [[volcanic]] areas, and the geyser effect is due to the proximity of [[magma]]. Surface water works its way down to an average depth of around {{convert|2000|m|ft}} where it contacts hot rocks. The pressurized water boils, and this causes the geyser effect of hot water and steam spraying out of the geyser's surface vent.

A geyser's eruptive activity may change or cease due to ongoing [[Deposition (geology)|deposition]] of [[mineral]]s within their plumbing, exchange of functions with nearby [[hot spring]]s, [[earthquake]] influences, and human intervention.<ref name=Bryan1995>{{cite book |last=Bryan |first=T. Scott |year=1995 |title=The geysers of Yellowstone |location=Niwot, Colorado |publisher=University Press of Colorado |isbn=0-87081-365-X}}</ref> Like many other natural phenomena, geysers are not unique to Earth. Jet-like eruptions, often called cryogeysers, have been observed on several of the [[Natural satellite|moons]] of the outer Solar System. Due to the low ambient pressures, these eruptions consist of vapour without liquid; they are made more easily visible by particles of dust and ice carried aloft by the gas. Water vapour jets have been observed near the south pole of [[Saturn]]'s moon [[Enceladus]], while [[nitrogen]] eruptions have been observed on [[Neptune]]'s moon [[Triton (moon)|Triton]]. There are also signs of [[Geysers on Mars|carbon dioxide eruptions]] from the southern polar ice cap of [[Mars]].

In the case of Enceladus, the plumes are believed to be driven by internal energy. In the cases of the venting on Mars and Triton, the activity may result from solar heating via a solid-state [[greenhouse effect]]. In all three cases, there is no evidence of the subsurface hydrological system which differentiates terrestrial geysers from other sorts of venting, such as [[fumarole]]s.