Cave 5778 225293586 2008-07-12T22:51:33Z WTucker 4108629 /* Patterns */ More consistent use of italics for terminology [[Image:Lechuguilla Cave Pearlsian Gulf.jpg|thumb|300px|[[Lechuguilla Cave]], New Mexico]] {{otheruses}} A '''cave''' is a natural underground void large enough for a human to enter. Some people suggest that the term 'cave' should only apply to cavities that have some part that does not receive daylight; however, in popular usage, the term includes smaller spaces like [[sea cave]]s, [[rock shelter]]s, and [[grotto]]s. [[Speleology]] is the science of exploration and study of all aspects of caves. Exploring a cave for recreation or science may be called "[[caving]]", "[[potholing]]", or occasionally (only in [[Canada]] and the [[United States]]), "[[spelunking]]". ==Types and formation== The formation and development of caves is known as ''[[speleogenesis]]''. Caves are formed by various [[geology|geologic]] processes. These may involve a combination of chemical processes, erosion from water, tectonic forces, microorganisms, pressure, atmospheric influences, and even [[Cave digging|digging]]. Most caves are formed in [[limestone]] by [[Solvation|dissolution]]. [[Image:HallOfTheMountainKings.jpg|300px|right|thumb|[[Speleothem]]s in Hall of the Mountain King, [[Ogof Craig a Ffynnon]], [[South Wales]].]] *''Solutional caves'' may form anywhere with rock that is soluble, and are most prevalent in [[limestone]], but can also form in other material, including [[chalk]], [[dolomite]], [[marble]], [[granite]], [[salt]], [[sandstone]], fossilized [[coral]] and [[gypsum]]. **The largest and most abundant solutional caves are located in limestone. Limestone dissolves under the action of rainwater and [[groundwater]] charged with H<sub>2</sub>CO<sub>3</sub> ([[carbonic acid]]) and naturally occurring [[organic acid]]s. The dissolution process produces a distinctive landform known as [[karst]], characterized by [[sinkhole]]s, [[sinking stream]]s, and underground drainage. Limestone caves are often adorned with calcium carbonate formations produced through slow precipitation. This include: [[flowstone]]s, [[stalactites]], [[stalagmites]], [[helictites]], draperies, [[soda straws]] and columns. These secondary mineral deposits in caves are called ''[[speleothem]]s''. **The world's most spectacularly decorated cave is generally regarded to be [[Lechuguilla Cave]] ([[New Mexico]], [[United States|USA]]). Lechuguilla and nearby [[Carlsbad Caverns]] are now believed to be examples of another type of solutional cave. They were formed by H<sub>2</sub>S ([[hydrogen sulfide]]) gas rising from below, where reservoirs of oil give off sulfurous fumes. This gas mixes with ground water and forms H<sub>2</sub>SO<sub>4</sub> ([[sulfuric acid]]). The acid then dissolves the limestone from below, rather than from above, by acidic water percolating from the surface. [[Image:hawaiian lava tube.jpg|thumb|300px|Exploring a lava tube in [[Hawaii]] ]] *Some caves are formed at the same time as the surrounding rock. These are sometimes called ''[[primary caves]]''. **[[Lava tube]]s are formed through [[volcanic]] activity and are the most common 'primary' caves. The [[lava]] flows downhill and the surface cools and solidifies. The hotter lava continues to flow under that crust, and if most of the liquid lava beneath the crust flows out, a hollow tube remains, thus forming a cavity. Examples of such caves can be found on [[Tenerife]], [[Hawaii (island)|Big Island]], and many other places. [[Kazumura Cave]] near [[Hilo]] is a remarkably long and deep lava tube; it is {{convert|65.6|km|sp=us}} long. **[[Blister cave]]s are also formed through volcanic activity. [[Image:Painted cave.jpg|300px|right|thumb|Painted Cave, a large sea cave, [[Santa Cruz Island]], [[California]]]] * ''[[Sea caves]]'' are found along coasts around the world. A special case is ''littoral caves'', which are formed by wave action in zones of weakness in sea cliffs. Often these weaknesses are faults, but they may also be dykes or bedding-plane contacts. Some wave-cut caves are now above sea level because of later uplift. Elsewhere, in places such as Thailand's [[Phang Nga Bay]], solutional caves have been flooded by the sea and are now subject to littoral erosion. Sea caves are generally around {{convert|5|m|sp=us}} to {{convert|50|m|sp=us}} in length but may exceed {{convert|300|m|sp=us}}. [[Image:Ice cave.jpg|300px|right|thumb|Glacier cave in Big Four Glacier, [[Big Four Mountain]], [[Washington]], ca. [[1920]].]] * ''[[Glacier caves]]'' occur in ice and under [[glacier]]s, formed by melting. They are also influenced by the very slow flow of the ice, which tends to close the caves again. (These are sometimes called ''[[ice caves]]'', though this term is properly reserved for caves that contain year-round ice formations). *''Fracture caves'' are formed when layers of more soluble minerals, such as gypsum, dissolve out from between layers of less soluble rock. These rocks fracture and collapse in blocks. *''Talus caves'' are the openings between rocks that have fallen down into a pile, often at the bases of cliffs. * ''[[Anchihaline caves]]'' are caves, usually coastal, containing a mixture of freshwater and saline water (usually sea water). They occur in many parts of the world, and often contain highly specialized and endemic faunas. ==Patterns== *''Branchwork caves'' resemble surface dentritic stream patterns; they are made up of passages that join downstream as tributaries. Branchwork caves are the most common of cave patterns and are formed near sinkholes where groundwater recharge occurs. Each passage or branch is fed by a separate recharge source and converges into other higher order branches downstream.<ref name=Easterbrook>Easterbrook, Don, 1999, ''Surface Processes and Landforms [2nd edition]'', New Jersey, Prentice Hall, pp. 207</ref> *''Angular Network caves'' form from intersecting fissures of carbonate rock that have had fractures widened by chemical erosion. These fractures form high, narrow, straight passages that persist in widespread closed loops.<ref name=Easterbrook /> *''Anastomotic caves'' largely resemble surface braided streams with their passages separating and then meeting further down drainage. They usually form along one bed or structure, and only rarely cross into upper or lower beds.<ref name=Easterbrook /> *''Spongework caves'' are formed as solution cavities are joined by mixing of chemically diverse water. The cavities form a pattern that is three-dimensional and random, resembling a sponge.<ref name=Easterbrook /> *''Ramiform caves'' form as irregular large rooms, galleries, and passages. These randomized three-dimensional rooms form from a rising water table that erodes the carbonate rock with hydrogen-sulfide enriched water.<ref name=Easterbrook /> ==Geographic distribution== Caves are found throughout the world, but only a portion of them have been explored and documented by [[cavers]]. The distribution of documented cave systems is widely skewed toward countries where [[caving]] has been popular for many years (such as [[France]], [[Italy]], [[Australia]], the [[United Kingdom|UK]], the [[United States]], etc.). As a result, explored caves are found widely in [[Europe]], [[Asia]], [[North America]], and [[Oceania]] but are sparse in [[South America]], [[Africa]], and [[Antarctica]]. This is a great generalization, as large expanses of North America and Asia contain no documented caves, whereas areas such as the [[Madagascar dry deciduous forests]] and parts of [[Brazil]] contain many documented caves. As the world’s expanses of soluble bedrock are researched by cavers, the distribution of documented caves is likely to shift. For example, [[China]], despite containing around half the world's exposed [[limestone]] - more than {{convert|1000000|km2|sp=us}} - has relatively few documented caves. ==Record lengths, depths, pitches and volumes== [[Image:Mammoth cave canyon.jpg|300px|right|thumb|Canyon passage in [[Mammoth Cave National Park|Mammoth Cave]], the world's longest cave.]] The cave system with the greatest total length of passage is [[Mammoth Cave National Park|Mammoth Cave]] ([[Kentucky]], [[United States|USA]]) at {{convert|591|km|sp=us}} in length. This record is unlikely to be surpassed in the near future, as the next most extensive known cave is [[Jewel Cave]] near [[Custer, South Dakota]], at {{convert|225|km|sp=us}}.<ref>http://www.caverbob.com/wlong.htm World’s Longest Caves List from The National Speleological Society</ref> The deepest known cave (measured from its highest entrance to its lowest point) is [[Voronya Cave]] ([[Abkhazia]], [[Georgia (country)|Georgia]]), with a depth of {{convert|2191|m|sp=us}}.<ref>http://www.caverbob.com/wdeep.htm World’s Deepest Caves List from The National Speleological Society</ref> This was the first cave to be explored to a depth of more than {{convert|2|km|sp=us}}. (The first cave to be descended below {{convert|1|km|sp=us}} was the famous [[Gouffre Berger]] in [[France]]). The [[Illyuzia-Mezhonnogo-Snezhnaya]] cave in [[Abkhazia]], [[Georgia (country)|Georgia]], ({{convert|1753|m|sp=us}}) and the [[Lamprechtsofen Vogelschacht]] Weg Schacht in [[Austria]] ({{convert|1632|m|sp=us}}) are the current second- and third-deepest caves. This particular record has changed several times in recent years. The deepest individual [[pitch (vertical space)|pitch]] (vertical drop) within a cave is {{convert|603|m|sp=us}} in [[Vrtoglavica Cave]] in [[Slovenia]], followed by [[Velebit caves|Patkov Gušt]] at {{convert|553|m|sp=us}} in the [[Velebit]] mountain, [[Croatia]]. The largest individual cavern ever discovered is the [[Sarawak chamber]], in the [[Gunung Mulu National Park]] ([[Miri]], [[Sarawak]], [[Borneo]], [[Malaysia]]), a sloping, boulder strewn chamber with an area of approximately {{convert|600|m|sp=us}} by {{convert|400|m|sp=us}} and a height of {{convert|80|m|sp=us}}. ==Ecology== [[Image:townsends in music hall.jpg|300px|left|thumb|Townsend's Big-eared bats in a cave]] Cave-inhabiting animals are often categorized as [[troglobite]]s (cave-limited species), [[troglophile]]s (species that can live their entire lives in caves, but also occur in other environments), [[trogloxene]]s (species that use caves, but cannot complete their life cycle wholly in caves) and accidentals (animals not in one of the previous categories). Some authors use separate terminology for aquatic forms (e.g., [[stygobite]]s, [[stygophile]]s, and [[stygoxene]]s). Of these animals, the troglobites are perhaps the most unusual organisms. Troglobitic species often show a number of characteristics, termed troglomorphies, associated with their adaptation to subterranean life. These characteristics may include a loss of pigment (often resulting in a pale or white coloration), a loss of eyes (or at least of optical functionality), an elongation of appendages, and an enhancement of other senses (such as the ability to sense vibrations in water). Aquatic troglobites (or stygobites), such as the endangered [[Alabama cave shrimp]], live in bodies of water found in caves and get nutrients from detritus washed into their caves and from the feces of bats and other cave inhabitants. Other aquatic troglobites include [[cave fish]], the [[Olm]], and cave salamanders such as the [[Texas Blind Salamander]]. [[Cave insects]] such as Oligaphorura (formerly Archaphorura) schoetti are troglophiles, reaching {{convert|1.7|mm|sp=us}} in length. They have extensive distribution and have been studied fairly widely. Most specimens are female but a male specimen was collected from [[St Cuthberts Swallet]] in 1969. [[Bat]]s, such as the [[Gray bat]] and [[Mexican Free-tailed Bat]], are trogloxenes and are often found in caves; they forage outside of the caves. Some species of [[cave cricket]]s are classified as trogloxenes, because they roost in caves by day and forage above ground at night. Because of the fragile nature of the cave ecosystem, and the fact that cave regions tend to be isolated from one another, caves harbor a number of [[endangered species]], such as the [[Tooth cave spider]], [[Liphistiidae]] Liphistius trapdoor spider, and the [[Gray bat]]. Caves are visited by many surface-living animals, including humans. These are usually relatively short-lived incursions, due to the lack of [[light]] and sustenance. ==Archaeological and social importance== [[Image:taino.jpg|300px|right|thumb|[[Taino]] [[petroglyph]]s in a cave in Puerto Rico]] Throughout history, primitive peoples have made use of caves for shelter, burial, or as religious sites. Since items placed in caves are protected from the climate and scavenging animals, this means caves are an archaeological treasure house for learning about these people. [[Cave painting]]s are of particular interest. One example is the [[Niah Caves|Great Cave of Niah]], in Malaysia, which contains evidence of human habitation dating back 40,000 years.<ref>''[[National Geographic]]''. James Shreeve. "The Greatest Journey". March 2006.</ref> In [[Germany]] some experts found signs of [[cannibalism]] in the caves at the [[Hönne]]. Caves are also important for geological research because they can reveal details of past climatic conditions in speleothems and [[sedimentary rock]] layers. Caves are frequently used today as sites for recreation. [[Caving]], for example, is the popular [[sport]] of cave exploration. For the less adventurous, a number of the world's prettier and more accessible caves have been converted into [[show cave]]s, where artificial lighting, floors, and other aids allow the casual visitor to experience the cave with minimal inconvenience. Caves have also been used for [[BASE jumping]] and [[cave diving]]. Caves are also used for the preservation or aging of wine and cheese. The constant, slightly chilly temperature and high humidity that most caves possess makes them ideal for such uses. ==See also== [[Image:Burger OtokKriznaJama.jpg|thumb|right|400px|Subterranean isle in [[Križna jama]]]] * [[Cave Conservancies]] * [[Cave Research Foundation]] * [[Caving]] * [[Flowstone]] * [[Grotto]] * [[List of caves]] * [[Mining]] * [[National Speleological Society]] * [[Pit Cave]] * [[Sinkhole]] * [[Speleology]] * [[Speleothem]] * [[Stalactite]] * [[Stalagmite]] * [[Wine caves]] ==References== {{reflist}} ==External links== {{Commons|Cave|Cave}} * [http://www.caves.org.au Australian Speleological Federation (ASF)], AU * [http://www.british-caving.org.uk/ British Caving Association (BCA)], UK * [http://www.showcaves.com/english/explain/Speleology/Classification.html Classification of Caves] A list of cave types with links to further information * [http://www.caves.org/pub/journal/ Journal of Cave and Karst Studies] * [http://www.caves.org/ National Speleological Society (NSS)], US * [http://www.uis-speleo.org/ International Union of Speleology (UIS)]. * [http://www.ssslib.ch/bbs/ Speleological Abstract (SA/BBS)] An annual review of the world's speleological literature. * [http://www.goodearthgraphics.com/virtcave The Virtual Cave] Photographs of many types of caves. * [http://www.cave-biology.org cave-biology.org] Cave biology (biospeleology) in India. * [http://discovercaves.com/tours.htm Tour Caves] A Google Map of Commercial Tour Caves in the US. 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