secondary mineral



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 caves, rock shelters, 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, in Canada and the United States, spelunking (see Caving).

Types and formation

The formation and development of caves is known as speleogenesis. Caves are formed by various geologic processes. These may involve a combination of chemical processes, erosion from water, tectonic forces, microorganisms, pressure, atmospheric influences, and even digging.

Most caves are formed in limestone by dissolution.

  • 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 H2CO3 (carbonic acid) and naturally occurring organic acids. The dissolution process produces a distinctive landform known as karst, characterized by sinkholes, sinking streams, and underground drainage. Limestone caves are often adorned with calcium carbonate formations produced through slow precipitation. This include: flowstones, stalactites, stalagmites, helictites, draperies, soda straws and columns. These secondary mineral deposits in caves are called speleothems.
    • The world's most spectacularly decorated cave is generally regarded to be Lechuguilla Cave in New Mexico. Lechuguilla and nearby Carlsbad Caverns are now believed to be examples of another type of solutional cave. They were formed by H2S (hydrogen sulfide) gas rising from below, where reservoirs of oil give off sulfurous fumes. This gas mixes with ground water and forms H2SO4 (sulfuric acid). The acid then dissolves the limestone from below, rather than from above, by acidic water percolating from the surface.
  • Some caves are formed at the same time as the surrounding rock. These are sometimes called primary caves.
    • Lava tubes 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, Big Island, and many other places. Kazumura Cave near Hilo is a remarkably long and deep lava tube; it is long.
    • Blister caves are also formed through volcanic activity.
  • Glacier caves occur in ice and under glaciers and are 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).


  • 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.

Geographic distribution


Record lengths, depths, pitches and volumes

The cave system with the greatest total length of surveyed passage is Mammoth Cave (Kentucky, USA) at 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 .

The deepest known cave (measured from its highest entrance to its lowest point) is Voronya Cave (Abkhazia, Georgia), with a depth of . This was the first cave to be explored to a depth of more than . (The first cave to be descended below was the famous Gouffre Berger in France). The Illyuzia-Mezhonnogo-Snezhnaya cave in Abkhazia, Georgia, and the Lamprechtsofen Vogelschacht Weg Schacht in Austria are the current second- and third-deepest caves. The deepest cave record has changed several times in recent years.

The deepest individual pitch (vertical drop) within a cave is in Vrtoglavica Cave in Slovenia. The second deepest is Patkov Gušt at 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 by and a height of .




Cave insects such as Oligaphorura (formerly Archaphorura) schoetti are troglophiles, reaching 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.




Archaeological and social importance






See also


External links

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