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, New Mexico]] 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 which does not receive daylight; however, in popular usage, the term includes smaller spaces like sea caves, Rock Shelter s and Grottos . 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 the United States ) " Spelunking ". TYPES AND FORMATION Caves are formed by Geologic processes. These may involve a combination of chemical processes, erosion from water, tectonic forces, microorganisms, pressure and atmospheric influences. Most caves are formed in Limestone by solution (see below). Primary caves Some caves are formed at the same time as the surrounding rock. These are called ''primary caves''.
Numerous lava tubes are found on Hawaii ( Big Island ). Kazumura Cave near Hilo is the longest and deepest lava tube of the world and also the eighth longest cave of the United States. It is 65.6km long.
, California ]]
, Washington , ca. 1920 .]]
s in Hall of the Mountain Kings, Ogof Craig A Ffynnon , South Wales .]]
The largest and most abundant solutional caves are located in limestone. Limestone dissolves under the action of rainwater and Groundwater charged with H2CO3 ( 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, including the most common and well-known Stalactite s and Stalagmite s. 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 , USA ). Lechuguilla and nearby Carlsbad Caverns are now believed to be examples of another type of solutional cave. They were formed by acid rising from below, where reservoirs of oil give off sulfurous fumes, rather than by acidic water percolating from the surface. CAVE 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 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 1,000,000 km&2 - has relatively few documented caves. , the world's longest cave.]] RECORD CAVES The system with the greatest total length of passage is Mammoth Cave ( Kentucky , USA ) at 579 km in length. This record is unlikely to be surpassed in the near future as the next most extensive known cave is the Optymistychna system in Ukraine , at 214 km. As Of 2005 , the deepest known cave (measured from its highest entrance to its lowest point) is Voronya Cave ( Abkhazia , Georgia ), with a depth of 2,140 m. This was the first cave to be explored to a depth of more than 2 km. (The first cave to be descended below 1 km was the famous Gouffre Berger in France ). The Gouffre Mirolda - Lucien Bouclier cave in France (1733 m) and the Lamprechtsofen Vogelschacht Weg Schacht in Austria (1632 m) are the current second and third deepest caves. This particular record has changed several times in recent years. The deepest individual Pitch (vertical drop) within a cave is 603 m in the Vrtoglavica cave in Slovenia , followed by Patkov Gušt (553 m) in the Velebit mountain, Croatia . The largest individual cavern ever discovered is the , Borneo , Malaysia ), a sloping, boulder strewn chamber with an area of approximately 600 m by 400 m and a height of 80 m. Since new caves are continually being explored, the various records of cave dimensions need to be updated fairly frequently. For information on a specific cave, see List Of Caves . The National Speleological Society Geo2 Committee on Long and Deep Caves INHABITANTS Cave-inhabiting animals are often categorized as Troglobite s (cave-limited species), Troglophile s (species which can live their entire lives in caves, but also occur in other environments), Trogloxene s (species which 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 faeces of bats and other cave inhabitants. Other aquatic troglobites include Cave Fish and the Olm . Cave Insects such as Oligaphorura (formerly Archaphorura) schoetti are troglophiles, reaching 1.7 mm 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. Some tropical caves of southeast Asia are rich in cave fauna and some even have cave flora . ARCHAEOLOGICAL AND SOCIAL IMPORTANCE 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 Great Cave Of Niah , which contains evidence of human habitation dating back 40,000 years.'' National Geographic ''. James Shreeve. "The Greatest Journey". March 2006. 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
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