Cave types and formation
Caves are formed by geologic processes. These may involve a combination of chemical processes, tectonic forces and atmospheric influences.
Some caves are formed at the same time as the surrounding rock, including lava tubes and blister caves. These are called primary caves. There are also secondary caves, which are formed inside the rock by processes which removes material, such as solution and erosion.
Erosion is a mechanical form of weathering which is caused by running water, a cave river which works on its bed deepening it or waves (on coasts).
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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 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 probably 80% of all caves on Earth. The main reason for the overwhelming number of karst caves is the fact that much of the surface is built of limestone, but also the slowness of the solution process. If it was faster, the lifespan of limestone caves would be much shorter and
their number much lower.
Limestone 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).
Caves can also form through the abrasive action of rivers, the wind, or the sea.
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 rather small. There are also some special cases; 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.
Lava 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.
The liquid lava inside the crust flows out and leaves a hollow tube.
The 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.
Records
Caves 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
Caves 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. That is another reason why caves should be protected from casual intrusion.
Caving is the sport of cave exploration.
See also
External links
In addition to the usual meaning of the term there are three locations in the United States with this name. 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.
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