Columnar jointing in the Alcantara Gorge, Sicily

Columnar jointing is a geological structure where sets of intersecting closely spaced fractures, referred to as

joints A joint or articulation (or articular surface) is the connection made between bones, ossicles, or other hard structures in the body which link an animal's skeletal system into a functional whole.Saladin, Ken. Anatomy & Physiology. 7th ed. McGraw- ...

, result in the formation of a regular array of polygonal prisms, or columns. Columnar jointing occurs in many types of igneous rocks and forms as the rock cools and contracts. Columnar jointing can occur in cooling lava flows and ashflow

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...

s (

ignimbrite Ignimbrite is a type of volcanic rock, consisting of hardened tuff. Ignimbrites form from the deposits of pyroclastic flows, which are a hot suspension of particles and gases flowing rapidly from a volcano, driven by being denser than the surro ...

s), as well as in some shallow intrusions. Columnar jointing also occurs rarely in

sedimentary rock Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...

s if they have been heated by nearby hot

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

. The columns can vary from 3 meters to a few centimeters in diameter, and can be as much as 30 meters tall. They are typically parallel and straight, but can also be curved and vary in diameter. An array of regular, straight, and larger-diameter columns is called a colonnade; an irregular, less-straight, and smaller-diameter array is termed an entablature. The number of sides of the individual columns can vary from 3 to 8, with 6 sides being the most common.Oregon State University > Volcano World > ... > Columnar Jointing
Accessed 29 December 2013.

Places

Some famous locations in the United States where columnar jointing can be found are the Devils Tower in Wyoming, the Devils Postpile in California and the Columbia River

flood basalt A flood basalt (or plateau basalt) is the result of a giant volcanic eruption or series of eruptions that covers large stretches of land or the ocean floor with basalt lava. Many flood basalts have been attributed to the onset of a hotspot reac ...

s in

Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Idaho. T ...

, Washington and

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyomi ...

. Other famous places include the

Giant's Causeway The Giant's Causeway is an area of about 40,000 interlocking basalt columns, the result of an ancient volcanic fissure eruption. It is located in County Antrim on the north coast of Northern Ireland, about three miles (5 km) northeast of ...

Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...

and

Fingal's Cave Fingal's Cave is a sea cave on the uninhabited island of Staffa, in the Inner Hebrides of Scotland, known for its natural acoustics. The National Trust for Scotland owns the cave as part of a national nature reserve. It became known as Finga ...

on the island of

Staffa Staffa ( gd, Stafa, , from the Old Norse for stave or pillar island) is an island of the Inner Hebrides in Argyll and Bute, Scotland. The Vikings gave it this name as its columnar basalt reminded them of their houses, which were built from ver ...

Scotland Scotland (, ) is a Countries of the United Kingdom, country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a Anglo-Scottish border, border with England to the southeast ...

Devils Tower

The Devils Tower in Wyoming in the United States is about 40 million years old and high. Geologists agree that the rock forming the Devils Tower solidified from an intrusion but it has not been established whether the

from this intrusion ever reached the surface. Most columns are 6-sided, but 4, 5, and 7-sided ones can also be found.

Giant's Causeway

The Giant's Causeway (

Irish Irish may refer to: Common meanings * Someone or something of, from, or related to: ** Ireland, an island situated off the north-western coast of continental Europe ***Éire, Irish language name for the isle ** Northern Ireland, a constituent unit ...

: ''Clochán An Aifir'') on the north Antrim coast of Northern Ireland was created by volcanic activity 60 million years ago, and consists of over 40,000 columns. According to a legend, the giant

Finn McCool Fionn mac Cumhaill ( ; Old and mga, Find or ''mac Cumail'' or ''mac Umaill''), often anglicized Finn McCool or MacCool, is a hero in Irish mythology, as well as in later Scottish and Manx folklore. He is leader of the ''Fianna'' bands of y ...

created the Giant's Causeway, as a causeway to Scotland.

Sōunkyō Gorge

Sōunkyō Gorge, a part of the town of Kamikawa, Hokkaido, Japan, features a 24-kilometer stretch of columnar jointing, which is the result of an eruption of the

Daisetsuzan Volcanic Group The is a volcanic group of peaks arranged around the wide caldera in Hokkaidō, Japan. In the Ainu language it is known as ''Nutapukaushipe'' (which means "the mountain above the river"),

30,000 years ago.

Deccan Traps

The late Cretaceous Deccan Traps of India constitute one of the largest volcanic provinces of Earth, and examples of columnar jointing can be found in St. Mary's Island in the state of Karnataka.

High Island Reservoir

Formed in Cretaceous, the columnar rocks are found around the reservoir and the islands nearby in Sai Kung,

Hong Kong Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delta i ...

. It is special that the rocks are not mafic, but felsic

instead.

Hexagonal volcanic tuffs at East Dam of High Island Reservoir 1

Makhtesh Ramon

The columnar jointed sandstone of the ''HaMinsara'' (Carpentry Shop) in the makhtesh (erosion cirque) of Makhtesh Ramon, Negev desert,

Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...

Cerro Kõi

There are several examples of columnar jointed sandstones in the greater

Asunción Asunción (, , , Guarani: Paraguay) is the capital and the largest city of Paraguay. The city stands on the eastern bank of the Paraguay River, almost at the confluence of this river with the Pilcomayo River. The Paraguay River and the Bay o ...

region of

Paraguay Paraguay (; ), officially the Republic of Paraguay ( es, República del Paraguay, links=no; gn, Tavakuairetã Paraguái, links=si), is a landlocked country in South America. It is bordered by Argentina to the south and southwest, Brazil to th ...

. The best known is Cerro Kõi in Areguá, but there are also several quarries in

Luque Luque () is a city in Central Department of Paraguay, part of the Gran Asunción metropolitan area. Both 1635 and 1750 have been recorded as dates of its founding. It was temporarily the capital of Paraguay in 1868 during the Paraguayan War b ...

Mars

Several exposures of columnar jointing have been discovered on the planet Mars by the High Resolution Imaging Science Experiment (

HiRISE High Resolution Imaging Science Experiment is a camera on board the '' Mars Reconnaissance Orbiter'' which has been orbiting and studying Mars since 2006. The 65 kg (143 lb), US$40 million instrument was built under the direction ...

) camera, which is carried by the

Mars Reconnaissance Orbiter ''Mars Reconnaissance Orbiter'' (MRO) is a spacecraft designed to study the geology and climate of Mars, provide reconnaissance of future landing sites, and relay data from surface missions back to Earth. It was launched on August 12, 2005, an ...

(MRO).

Sawn Rocks

Sawn Rocks, in Mount Kaputar National Park close to Narrabri,

New South Wales, Australia ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

, features 40 meters of columnar jointing above the creek and 30 meters below the surface.Sawn Rocks walking track, Mount Kaputar National Park
NSW National Parks and Wildlife Service. Retrieved 3 January 2019.

Basaltic Prisms of Santa María Regla

Alexander von Humboldt documented the prisms located in Huasca de Ocampo, in the Mexican state of Hidalgo.

Columnar Basalt of Tawau (Batu Bersusun)

River flows through the area of columnar basalt. One section is seen vertically high on river bank. The rest lays on river bank. Water flows from the lowest area forming waterfall and scenic view. Location is at Kampung Balung Cocos, Tawau

References

External links

*Aydin, A., and J. Zhong (nda
Columnar Joints

Stanford University, Stanford, California. {{Structural geology Igneous rocks Geomorphology Structural geology Metamorphic rocks