Cave

\nA cave is a natural underground void.

Table of contents

1 Cave types and formation 1.1 Primary caves 1.2 Secondary caves 2 Distribution 3 Records 4 Archaeological and social importance 5 See also 6 External links 7 Other uses of 'Cave'

Cave types and formation

\nCaves are formed by geologic processes. These may involve a combination of chemical processes, tectonic forces and atmospheric influences.

Primary caves

\nSome caves are formed at the same time as the surrounding rock. These are called primary caves.\n]]\nLava tubes are formed through volcanic activity. They are the most common primary caves. Lava flows downhill and the surface cools down and becomes hard. The lava now flows inside its crust, until the eruption ends. \nThe liquid lava inside the crust flows out and leaves a hollow tube. \nThe most important 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. Blister caves are also formed through volcanic activity.

Secondary caves

\nSecondary caves are formed inside the rock after the rock itself has formed by processes which removes material such as solution and erosion. Erosion is a mechanical form of weathering which is caused by the abrasive action of wind or water.

• Sea caves are very common at all coasts of the world, but as they are restricted to the zone where waves work on the rocks of the coast they are generally rather small.

, Washington, ca. 1920]]\n* Ice caves occur in and under glaciers, formed by melting. They are also influenced by the very slow flow of the ice which tends to close the caves again. Solutional caves may form anywhere with rock which is soluble, and are most prevalent in limestone, but can also form in other material, including chalk, dolomite, marble, loess, ice, granite, salt, lava, sandstone, and gypsum. The most common process of cave formation is karstification, which is the solution of rocks by rain water. Cave formation in limestone occurs because limestone dissolves under the action of rainwater and groundwater charged with CO₂ (carbonic acid) and naturally occurring organic acids. The dissolution process produces a distinctive landform known as karst and characterized by sinkholes, sinking streams, and underground drainage. Limestone solution is the single most important process forming caves and the origin of the great majority of all caves on Earth. The reason for this abundance is the facts that limestone is so common and the slowness of the solution process. If it was faster, the lifespan of limestone caves would be much shorter and their number much lower. in Hall of the Mountain Kings, Ogof Craig a Ffynnon, South Wales]]\nLimestone caves are often adorned with calcium carbonate formations produced through slow precipitation, including the most common and well-known stalactites and stalagmites. These secondary mineral deposits in caves are called speleothems. The world's most spectacularly decorated cave is generally regarded to be Lechuguilla Cave (New Mexico, USA).

Distribution

\nCaves are sparse in South America, Africa, and Antarctica, but are found widely in Europe, Asia, and North America. The distribution of cave systems so far discovered is widely skewed toward countries where caving is popular (such as the USA, France, the UK etc.). It is likely that many more systems will be discovered, especially in China, which, despite containing around half the world's exposed limestone - more than 1,000,000 km² - has hardly been explored underground.

Records

\nCaves can reach considerable dimensions. Of the cave systems that have been discovered so far, the most extensive is Mammoth Cave (Kentucky, USA) with 560km of passages. The deepest known cave (2004) is Voronja Cave (Georgia), with a depth of 1,710m, but this title has recently been needed to be updated frequently as exploration of new cave progresses. The largest individual cavern found is the Gua Niah (also known as the Sarawak Chamber), Deer Cave (Borneo, Malaysia) with an area of approximately 600m by 400m and a height of 80m.

Archaeological and social importance

\nCaves are also an archaeological treasure house as primitive people used caves as their shelter and sometimes burial place. Items placed in caves are protected from climate and scavanging animals. One example is the Great Cave of Niah, which is one of the largest limestone caves in the world as well as an archaeological treasure house. It was here that archaeologists discovered the evidence of Man’s existence dating back 40,000 years. Caving is the sport of cave exploration.

See also

\n* Quarries\n* Mines\n* List of caves\n* Cave painting\n* Cavus

External links

\n* About Gua Niah\n* British Caving Association (BCA), UK\n* Classification of Caves Very detailed list of cave types with links to further information\n* National Speleological Society (NSS), US\n* NSS Geo2 Committee on Long and Deep Caves A website with numerous pages on cave world records, e.g., the longest and deepest caves; compiled by Bob Gulden\n* Ogof Ffynnon Ddu Virtual tour etc.\n* The Virtual Cave A site with exceptional photography by Dave Bunnell, the editor of the NSS News. Make a virtual caving trip!

Other uses of 'Cave'

In addition to the usual meaning of the term there are three places in the United States called Cave. They are in Stevens County, Kansas, Lincoln County, Missouri and Pendleton County, West Virginia. Cave is a town in New Zealand. Caves is also the name of a commune in the Aude département, in France CAVE is the Cave Automatic Virtual Environment for immersive virtual reality simulations. Category:Subterranea\nCategory:Geology\nCategory:Landforms\n