# Volcanic plug

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{{short description|Volcanic object created when magma hardens within a vent on an active volcano}}
{{More citations needed|date=June 2013}}
[[File:Pitonpair.JPG|right|thumb|250px|An aerial view of the [Gros Piton](/source/Gros_Piton) and [Petit Piton](/source/Petit_Piton), in [St. Lucia](/source/St._Lucia), 2006.]]
A '''volcanic plug''', also called a '''volcanic neck''' or '''lava neck''', is a [volcanic](/source/volcano) object created when [magma](/source/magma) hardens within a [vent](/source/Volcanic_vent) on an active volcano. When present, a plug can cause an extreme build-up of high gas [pressure](/source/pressure) if rising [volatile](/source/Volatile_(astrogeology))-charged magma is trapped beneath it, and this can sometimes lead to an explosive eruption.  In a [plinian eruption](/source/plinian_eruption) the plug is destroyed and ash is ejected.<ref name="vlh">{{cite journal |last1=Huff |first1=W.D. |last2=Owen |first2=L.A. |date=2013 |title=Volcanic Landforms and Hazards |url=https://www.sciencedirect.com/science/article/pii/B9780123747396000890 |journal=Treatise on Geomorphology |volume=5 |issue= |pages=155 |doi=10.1016/B978-0-12-374739-6.00089-0 |isbn=9780080885223 |access-date=|url-access=subscription }}</ref>

[Glacial](/source/Glaciation) [erosion](/source/erosion) can lead to exposure of the plug on one side, while a long slope of material remains on the opposite side. Such landforms are called [crag and tail](/source/crag_and_tail). If a volcanic plug is later covered by softer, looser layers of [tephra](/source/tephra), such as ash and [hydrothermally altered](/source/hydrothermal_circulation) lava,<ref>{{cite web |date=14 March 2023 |title=How does hot water bring down volcanic slopes? |url=https://www.usgs.gov/observatories/calvo/news/altered-states-volcanic-rock#:~:text=Hydrothermal%20alteration%20changes%20primary%20volcanic,%2C%20yellow%2C%20and%20orange%20rocks! |website=U.S. Geological Survey |access-date=25 March 2026}}</ref> then agents of erosion may in time remove that softer surrounding rock while the plug's harder, less erodible congealed magma remains, producing a distinctive upstanding, necklike landform.<ref>{{cite web |title=Volcanic Necks and Plugs |url=https://www.nps.gov/articles/000/volcanic-necks-and-plugs.htm#:~:text=Volcanic%20necks%20and%20plugs%20are,of%20the%20former%20eruptive%20vent. |website=National Park Service |access-date=25 March 2026}}</ref><ref>{{cite web |title=Volcanic Rocks and Features |url=https://www.ncei.noaa.gov/access/metadata/landing-page/bin/iso?id=gov.noaa.ngdc.mgg.photos:G01222 |website=National Centers for Environmental Information |publisher=National Oceanic and Atmospheric Administration |access-date=25 March 2026}}</ref>

== Examples of volcanic plugs ==
[[File:Rhumsiki Peak.jpg|thumb|Volcanic plug near [Rhumsiki](/source/Rhumsiki), [Cameroon](/source/Cameroon).]]

=== Africa ===
Near the village of [Rhumsiki](/source/Rhumsiki) in the [Far North Province](/source/Far_North_Region_(Cameroon)) of [Cameroon](/source/Cameroon), Kapsiki Peak is an example of a volcanic plug and is one of the most photographed parts of the [Mandara Mountains](/source/Mandara_Mountains). Spectacular volcanic plugs are present in the center of [La Gomera](/source/La_Gomera) island in the [Canary Islands](/source/Canary_Islands) archipelago, within the [Garajonay National Park](/source/Garajonay_National_Park). [The Pico Cão Grande](/source/Pico_C%C3%A3o_Grande) (Portuguese for "Great Dog Peak") is a landmark needle-shaped volcanic plug peak in São Tomé and Príncipe, in the Caué District of São Tomé Island in Parque Natural Obô de São Tomé. Its summit is 663 m (2,175 ft) above sea level,[1] and it rises about 370 m (1,210 ft) over the surrounding terrain.[2] 
[[File:Roque Bentayga visto desde Artenara.jpg|thumb|[Roque Bentayga](/source/Roque_Bentayga) from the town of [Artenara](/source/Artenara)]]

=== Asia ===
[Sigiriya](/source/Sigiriya) is an ancient rock fortress near the town of [Dambulla](/source/Dambulla) in [Sri Lanka](/source/Sri_Lanka). Approximately 180m high, it is now a UNESCO listed [World Heritage Site](/source/World_Heritage_Site).<ref>{{cite web |last1=Voiland |first1=Adam |title=Sri Lanka's Granite Fortress |url=https://earthobservatory.nasa.gov/images/149543/sri-lankas-granite-fortress |website=NASA Earth Observatory |date=5 March 2022 |access-date=24 November 2024}}</ref>

=== Europe ===
[[File:Rocher St Michel à Aiguilhe.JPG|thumb|upright|[Saint Michel d'Aiguilhe](/source/Saint_Michel_d'Aiguilhe) chapel, on top of a volcanic plug in [Le Puy-en-Velay](/source/Le_Puy-en-Velay), France.]]

[Borgarvirki](/source/Borgarvirki) is a volcanic plug located in north Iceland.

A volcanic plug is situated in the town of [Motta Sant'Anastasia](/source/Motta_Sant'Anastasia) in Italy.

[Saint Michel d'Aiguilhe](/source/Saint_Michel_d'Aiguilhe) chapel, whose construction started in 969,<ref>{{Base Mérimée|PA00092565|Eglise Saint-Michel}}</ref> near [Le Puy-en-Velay](/source/Le_Puy-en-Velay) in France. The volcanic plug rises about {{convert|85|m}} above the surroundings. Another building on a volcanic plug is the 14th century [Trosky Castle](/source/Trosky_Castle) in the [Czech Republic](/source/Czech_Republic).  [Strombolicchio](/source/Strombolicchio), the northernmost of the [Aeolian Islands](/source/Aeolian_Islands), and [Rockall](/source/Rockall), a small, uninhabited, remote [islet](/source/islet) in the North [Atlantic Ocean](/source/Atlantic_Ocean), are also volcanic plugs.

In the [United Kingdom](/source/United_Kingdom), two examples of a building on a volcanic plug are the [Castle Rock](/source/Castle_Rock_(Edinburgh)) in [Edinburgh](/source/Edinburgh), Scotland, and [Deganwy Castle](/source/Deganwy_Castle), [Wales](/source/Wales). The [Law, Dundee](/source/Law%2C_Dundee), [Ailsa Craig](/source/Ailsa_Craig), [Bass Rock](/source/Bass_Rock), [North Berwick Law](/source/North_Berwick_Law) and [Dumgoyne](/source/Dumgoyne) hill are other examples of volcanic plugs located in [Scotland](/source/Scotland). There are over 30 volcanic plugs in [Northern Ireland](/source/Northern_Ireland), including [Slemish](/source/Slemish) in [Ballymena](/source/Ballymena), [Tievebulliagh](/source/Tievebulliagh), [Scawt Hill](/source/Scawt_Hill), [Carrickarede](/source/Carrick-a-Rede_Rope_Bridge), [Scrabo](/source/Scrabo_Tower) and [Slieve Gallion](/source/Slieve_Gallion).<ref name="hmso">Wilson, H E et al (1986) Geological Survey of Northern Ireland, HMSO</ref>

=== North America and the Caribbean === 

There are several volcanic plugs in the [United States](/source/United_States), including [Morro Rock](/source/Morro_Rock) in [California](/source/California), Devils Elbow located in the [Heceta Head Lighthouse](/source/Heceta_Head_Lighthouse) Scenic State Park on the [Oregon](/source/Oregon) coast, Thumb Butte in the [Sierra Prieta](/source/Sierra_Prieta) of Arizona and Agathla Peak near [Monument Valley](/source/Monument_Valley), and [Shiprock](/source/Shiprock) and [Cabezon Peak](/source/Cabezon_Peak), both found in [New Mexico](/source/New_Mexico). [Devils Tower](/source/Devils_Tower) in [Wyoming](/source/Wyoming) and [Little Devils Postpile](/source/Little_Devils_Postpile) in [Yosemite National Park](/source/Yosemite_National_Park), California, are also believed, by many [geologist](/source/geologist)s, to be volcanic plugs.  In Canada, the [Northern Cordilleran Volcanic Province](/source/Northern_Cordilleran_Volcanic_Province) gives rise to several confirmed and suspected plugs. Chief among these is [Castle Rock](/source/Castle_Rock_(volcano)), located in [British Columbia](/source/British_Columbia), which last erupted during the [Pleistocene](/source/Pleistocene).  The southern coast of [Saint Lucia](/source/Saint_Lucia) is dominated by the iconic [Pitons](/source/Pitons_(Saint_Lucia)), a [UNESCO](/source/UNESCO) [World Heritage Site](/source/World_Heritage_Site). The twin peaks, Gros Piton and Petit Piton, steeply rise more than {{convert|770|m|ft}} above the [Caribbean](/source/Caribbean_Sea).

=== South America ===

[Pinnacle Rock, Galápagos, Ecuador](/source/Pinnacle_Rock_(Gal%C3%A1pagos)).

=== Oceania === 

There are several volcanic plugs in the [North Island](/source/North_Island) of [New Zealand](/source/New_Zealand), including:
* the Pinnacles in the [Coromandel Peninsula](/source/Coromandel_Peninsula)
* [Bream Head](/source/Bream_Head) in [Northland](/source/Northland_Region)
* Paritutu and the adjacent [Sugar Loaf Islands](/source/Sugar_Loaf_Islands) in [Taranaki](/source/Taranaki)
* St. Paul's Rock at [Whangaroa Harbour](/source/Whangaroa_Harbour)
* [Piha](/source/Piha)'s Lion Rock, which hosted a fortified [Maori](/source/M%C4%81ori_people) [pā](/source/p%C4%81)
* Mount Pohaturoa near the village of [Ātiamuri](/source/%C4%80tiamuri), a distinctive sight for travelers along [State Highway 1](/source/State_Highway_1_(New_Zealand))

In New Zealand's [South Island](/source/South_Island), [Onawe Peninsula](/source/%C5%8Cnawe_Peninsula) on [Banks Peninsula](/source/Banks_Peninsula) is a prominent volcanic plug, and erosion of [Saddle Hill](/source/Saddle_Hill_(New_Zealand)) near [Dunedin](/source/Dunedin) has also revealed a plug. Dunedin's [Mount Cargill](/source/Mount_Cargill) displays two plugs: its main summit and the subsidiary summit of Buttar's Peak.

In [Australia](/source/Australia), [The Nut](/source/The_Nut_(Tasmania)) in [Tasmania](/source/Tasmania) are further examples, along with [Mount Warning](/source/Mount_Warning) and the several peaks in the [Warrumbungles](/source/Warrumbungles) in New South Wales. The 11 peaks of the [Glasshouse Mountains National Park](/source/Glass_House_Mountains_National_Park) including [Mount Beerwah](/source/Mount_Beerwah), [Mount Tibrogargan](/source/Mount_Tibrogargan), [Mount Coonowrin](/source/Mount_Coonowrin), [Mount Cooroora](/source/Mount_Cooroora), [Mount Ngungun](/source/Mount_Ngungun), Mount Tibberoowuccum, Mount Tunbubudla, and Mount Beerburrum, in [South East Queensland](/source/South_East_Queensland) are volcanic plugs.<ref>{{cite web |url=https://www.australia.com/en/places/brisbane-and-surrounds/guide-to-the-glass-house-mountains.html |title=Guide to the Glass House Mountains – Tourism Australia |date=21 July 2021 }}</ref><ref>{{cite web
 |url= http://www.geomaps.com.au/scripts/mountwarning.php
 |work= Geological sites of NSW
 |title= Wollumbin/Mt Warning Shield Volcano
 |publisher= Cartoscope Pty Limited
 |access-date= 30 June 2013
 |archive-date= 22 June 2013
 |archive-url= https://web.archive.org/web/20130622034644/http://www.geomaps.com.au/scripts/mountwarning.php
 |url-status= dead
 }}</ref>

== Gallery ==
<gallery mode="packed" widths="100">
Edinburgh Castle From Princes Street Garden 001.jpg|[Edinburgh Castle](/source/Edinburgh_Castle) in [Scotland](/source/Scotland) is built upon an [ancient volcanic plug](/source/Castle_Rock_(Edinburgh)).
Mt Popa.jpg|[Taung Kalat](/source/Mount_Popa), Burma.
Strombolicchio2.jpg|[Strombolicchio](/source/Strombolicchio) Island and its lighthouse, close to Stromboli Island ([Aeolian Islands](/source/Aeolian_Islands), Italy).
RoqueNublo2.jpg|[Roque Nublo](/source/Roque_Nublo), symbol of [Gran Canaria](/source/Gran_Canaria) island.
Slemish (8) - geograph.org.uk - 834986.jpg|[Slemish](/source/Slemish), a volcanic plug in [Northern Ireland](/source/Northern_Ireland), is traditionally associated with [St Patrick](/source/St_Patrick).
TroskyCastle.JPG|[Trosky Castle](/source/Trosky_Castle) ("Panna" Tower), Czech Republic.
Devils_Tower.jpg|[Devils Tower](/source/Devils_Tower), Wyoming, USA.
File:Shiprock.snodgrass3.jpg|[Shiprock](/source/Shiprock), New Mexico, USA.
File:Whangaroa_Harbour3.JPG|St. Paul's Rock, above [Whangaroa Harbour](/source/Whangaroa_Harbour), Northland, New Zealand.
São Tomé - Pico Cão Grande.jpg|[Pico Cão Grande](/source/Pico_C%C3%A3o_Grande), landmark volcanic plug peak on [São Tomé Island](/source/S%C3%A3o_Tom%C3%A9_Island) (São Tomé and Príncipe), rising over {{convert|300|m}} above the surroundings.
Dent_de_la_Rancune,_voie_normale.png|Dent de la Rancune, a challenging climbing site in the [Chaîne des Puys](/source/Cha%C3%AEne_des_Puys), France.
File:Crater Bluff Warrumbungles.jpg|Crater Bluff in the [Warrumbungles](/source/Warrumbungles), New South Wales

</gallery>
{{Commons category|Volcanic plugs}}

== References ==
{{Reflist}}

{{Earth's landforms}}

Category:Volcanic plugs
Category:Volcanic landforms

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Adapted from the Wikipedia article [Volcanic plug](https://en.wikipedia.org/wiki/Volcanic_plug) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Volcanic_plug?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.