Editing Geyser (section)

=== General categorization ===

There are two types of geysers: ''fountain geysers'' which erupt from pools of water, typically in a series of intense, even violent, bursts; and ''cone geysers'' which erupt from cones or mounds of [[siliceous sinter]] (including [[geyserite]]), usually in steady jets that last anywhere from a few seconds to several minutes. [[Old Faithful Geyser|Old Faithful]], perhaps the best-known geyser at Yellowstone National Park, is an example of a cone geyser. [[Grand Geyser]], the tallest predictable geyser on Earth (although [[Geysir]] in Iceland is taller, it is not predictable), also at Yellowstone National Park, is an example of a fountain geyser.<ref>{{cite book |last=Bryan |first=T. Scott |title=The Geysers of Yellowstone |edition=Fifth |location=United States |publisher=University Press of Colorado |year=2018}}</ref>

{{multiple image
 |direction = horizontal
 |align     = left
 |width1    = 202
 |width2    = 180
 |image1    = Fountain geyser.jpg
 |image2    = Old Faithful Geyser Yellowstone National Park.jpg
 |alt1      = Geyser erupts up and blows sideways from a pool.
 |alt2      = High geyser of water erupts out of the sparsely vegetated earth.
 |footer    = [[Fountain Geyser]] erupting from the pool (left) and [[Old Faithful geyser]] (cone geyser having mound of siliceous sinter) in [[Yellowstone National Park]] erupts approximately every 91 minutes (right).
}}

There are many volcanic areas in the world that have [[hot spring]]s, [[mud pot]]s and [[fumarole]]s, but very few have erupting geysers. The main reason for their rarity is that multiple intense transient forces must occur simultaneously for a geyser to exist. For example, even when other necessary conditions exist, if the rock structure is loose, eruptions will erode the channels and rapidly destroy any nascent geysers.<ref>{{Cite thesis |last=Brown |first=Sabrina |year=2019 |title=Diatom-inferred records of paleolimnological variability and continental hydrothermal activity in Yellowstone National Park, USA |url=https://digitalcommons.unl.edu/geoscidiss/122 |type=PhD dissertation |publisher=University of Nebraska–Lincoln}}</ref>

Geysers are fragile, and if conditions change, they may go dormant or extinct. Many have been destroyed simply by people throwing debris into them, while others have ceased to erupt due to dewatering by [[geothermal power]] plants. However, the Geysir in Iceland has had periods of activity and dormancy. During its long dormant periods, eruptions were sometimes artificially induced—often on special occasions—by the addition of [[surfactant]] soaps to the water.<ref name="Pasvanoglu_etal_2000">{{cite journal |title=Geochemical Study of the Geysir Geothermal Field in Haukadalur, S. Iceland |first1=S. |last1=Pasvanoglu |first2=H. |last2=Kristmannsdóttir |first3=S. |last3=Björnsson |first4=H. |last4=Torfason |journal=Proceedings World Geothermal Congress 2000 |year=2000}}</ref>
{{Clear}}