Blowhole (geology): Difference between revisions
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[[File:Blowhole1.svg|thumb|right|Sea based blowhole.]] |
[[File:Blowhole1.svg|thumb|right|Sea based blowhole.]] |
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[[File:Blowhole2.svg|thumb|right|Land based blowhole.]] |
[[File:Blowhole2.svg|thumb|right|Land based blowhole.]] |
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In [[geology]], a '''blowhole''' is formed as [[sea cave]]s grow landwards and upwards into vertical shafts and expose themselves towards the surface, which can result in blasts of water from the top of the blowhole<ref>{{cite book |title=Engineering geology |last=Bell |first=F. G. |author2=Frederic Gladstone Bell |year=2007 |publisher=Elsevier |isbn=978-0-7506-8077-6 |page=140}}</ref> if the [[geometry]] of the cave and blowhole and state of the [[weather]] are appropriate. |
In [[geology]], a '''blowhole''' is formed as [[sea cave]]s grow landwards and upwards into vertical shafts and expose themselves towards the surface, which can result in blasts of water from the top of the blowhole<ref>{{cite book |title=Engineering geology |last=Bell |first=F. G. |author2=Frederic Gladstone Bell |year=2007 |publisher=Elsevier |isbn=978-0-7506-8077-6 |page=140}}</ref> if the [[geometry]] of the cave and blowhole and state of the [[weather]] are appropriate.<ref name=":2" /> |
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=== Mechanics === |
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| ⚫ | A ''blowhole'' is also the name of a rare geologic feature in which air is blown through a small hole at the surface due to [[pressure]] differences between a closed underground system and the surface. The blowholes of [[Wupatki National Monument]] are an example of such a phenomenon. It is estimated that the closed underground passages have a volume of at least seven billion cubic feet. Wind speeds can approach 30 miles per hour.<ref>{{cite book |first1= James Doyne |last1=Sartor |first2=D. L. |last2=Lamar |title=Meteorological-Geological Investigations of the Wupatki Blowhole System |location=Santa Monica, CA |publisher=RAND Corporation |year=1962 |url=http://www.rand.org/pubs/research_memoranda/RM3139 |oclc=22486021}}{{Page needed|date=July 2011}}</ref> Another well known example of the blowhole is the natural entrance to the [[Wind Cave National Park|Wind Cave]]<ref>Rodney D. Horrocks and Bernard W. Szukalski; ''[https://caves.org/pub/journal/PDF/V64/v64n1-Horrocks.pdf Using geographic information systems to develop a cave potential map for Wind Cave, South Dakota]''; Journal of Cave and Karst Studies 64 (1): 63-70.</ref> |
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Blowholes are likely to occur in areas where there are crevices, such as [[Lava tube|lava tubes]], in rock along the coast.<ref name=":0">{{Cite book|title = Blowholes|url = http://link.springer.com/referenceworkentry/10.1007/978-90-481-2639-2_189|publisher = Springer Netherlands|date = 2011-01-01|isbn = 978-90-481-2638-5|pages = 163-164|doi = 10.1007/978-90-481-2639-2_189|language = en|first = Colin D.|last = Woodroffe}}</ref> These areas are often located along [[Fault (geology)|fault lines]] and on islands.<ref name=":0" /> As powerful waves hit the coast, water rushes into these crevices and bursts out in a high pressured release.<ref name=":0" /> It is often accompanied by a loud noise and wide spray, and for this reason, blowholes are often sites of tourism. <ref name=":0" /> |
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=== Ecological Impacts === |
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Blowholes have the capacity to change the topography near their locations. Blowholes can eventually erode the area surrounding the crevices to form larger sea caves.<ref name=":1">{{Cite journal|url = http://www.jstor.org.libezp.lib.lsu.edu/stable/4298348?Search=yes&resultItemClick=true&searchText=blowhole&searchUri=%2Faction%2FdoBasicSearch%3FQuery%3Dblowhole%26amp%3Bfilter%3Diid%253A10.2307%252Fi394720&seq=11#page_scan_tab_contents|title = Coastal Geomorphology of Andesite from the Cretaceous Alisitos Formation in Baja California (Mexico)|last = Clark|first = Hovey C.|date = 1995|journal = Journal of Coastal Research|doi = |pmid = |access-date = |last2 = Johnson|first2 = Markes E.|issue = 2|volume = 11|page = 401-414}}</ref> In some instances, the cave itself may collapse.<ref name=":1" /> This event may create shallow pools along the coast.<ref>{{Cite journal|title = Galapagos Islands: Geological Field Notes: New Data|url = http://www.jstor.org/stable/3627258|journal = Transactions of the Kansas Academy of Science (1903-)|date = 1978-10-01|pages = 231-241|volume = 81|issue = 3|doi = 10.2307/3627258|first = Paul|last = Tasch}}</ref> |
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=== Other === |
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| ⚫ | A ''blowhole'' is also the name of a rare geologic feature in which air is blown through a small hole at the surface due to [[pressure]] differences between a closed underground system and the surface. The blowholes of [[Wupatki National Monument]] are an example of such a phenomenon. It is estimated that the closed underground passages have a volume of at least seven billion cubic feet. Wind speeds can approach 30 miles per hour.<ref name=":2">{{cite book |first1= James Doyne |last1=Sartor |first2=D. L. |last2=Lamar |title=Meteorological-Geological Investigations of the Wupatki Blowhole System |location=Santa Monica, CA |publisher=RAND Corporation |year=1962 |url=http://www.rand.org/pubs/research_memoranda/RM3139 |oclc=22486021}}{{Page needed|date=July 2011}}</ref> Another well known example of the blowhole is the natural entrance to the [[Wind Cave National Park|Wind Cave]]<ref>Rodney D. Horrocks and Bernard W. Szukalski; ''[https://caves.org/pub/journal/PDF/V64/v64n1-Horrocks.pdf Using geographic information systems to develop a cave potential map for Wind Cave, South Dakota]''; Journal of Cave and Karst Studies 64 (1): 63-70.</ref> |
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<gallery widths="220px" heights="220px" perrow="2"> |
<gallery widths="220px" heights="220px" perrow="2"> |
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Image:Kudawella-blowhole-sri-lanka.JPG|[[Hummanaya]] - A blowhole located in Southern Province, [[Sri Lanka]]. |
Image:Kudawella-blowhole-sri-lanka.JPG|[[Hummanaya]] - A blowhole located in Southern Province, [[Sri Lanka]]. |
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Image:Nakalele-Blowhole-Maui.jpg|[[Nakalele Point|Nakalele]] blowhole, located near [[Nakalele Point]] in north western [[Maui]], Hawaii. |
Image:Nakalele-Blowhole-Maui.jpg|[[Nakalele Point|Nakalele]] blowhole, located near [[Nakalele Point]] in north western [[Maui]], Hawaii. |
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</gallery |
</gallery> |
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==References== |
==References== |
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Revision as of 22:48, 23 November 2015
In geology, a blowhole is formed as sea caves grow landwards and upwards into vertical shafts and expose themselves towards the surface, which can result in blasts of water from the top of the blowhole[1] if the geometry of the cave and blowhole and state of the weather are appropriate.[2]
Mechanics
Blowholes are likely to occur in areas where there are crevices, such as lava tubes, in rock along the coast.[3] These areas are often located along fault lines and on islands.[3] As powerful waves hit the coast, water rushes into these crevices and bursts out in a high pressured release.[3] It is often accompanied by a loud noise and wide spray, and for this reason, blowholes are often sites of tourism. [3]
Ecological Impacts
Blowholes have the capacity to change the topography near their locations. Blowholes can eventually erode the area surrounding the crevices to form larger sea caves.[4] In some instances, the cave itself may collapse.[4] This event may create shallow pools along the coast.[5]
Other
A blowhole is also the name of a rare geologic feature in which air is blown through a small hole at the surface due to pressure differences between a closed underground system and the surface. The blowholes of Wupatki National Monument are an example of such a phenomenon. It is estimated that the closed underground passages have a volume of at least seven billion cubic feet. Wind speeds can approach 30 miles per hour.[2] Another well known example of the blowhole is the natural entrance to the Wind Cave[6]
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Blowholes, north coast of Barbados -
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References
- ^ Bell, F. G.; Frederic Gladstone Bell (2007). Engineering geology. Elsevier. p. 140. ISBN 978-0-7506-8077-6.
- ^ a b Sartor, James Doyne; Lamar, D. L. (1962). Meteorological-Geological Investigations of the Wupatki Blowhole System. Santa Monica, CA: RAND Corporation. OCLC 22486021.[page needed]
- ^ a b c d Woodroffe, Colin D. (2011-01-01). Blowholes. Springer Netherlands. pp. 163–164. doi:10.1007/978-90-481-2639-2_189. ISBN 978-90-481-2638-5.
- ^ a b Clark, Hovey C.; Johnson, Markes E. (1995). "Coastal Geomorphology of Andesite from the Cretaceous Alisitos Formation in Baja California (Mexico)". Journal of Coastal Research. 11 (2): 401-414.
- ^ Tasch, Paul (1978-10-01). "Galapagos Islands: Geological Field Notes: New Data". Transactions of the Kansas Academy of Science (1903-). 81 (3): 231–241. doi:10.2307/3627258.
- ^ Rodney D. Horrocks and Bernard W. Szukalski; Using geographic information systems to develop a cave potential map for Wind Cave, South Dakota; Journal of Cave and Karst Studies 64 (1): 63-70.
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