A cave is a hollow place in the ground, specifically a natural
underground space large enough for a human to enter. Caves form
naturally by the weathering of rock and often extend deep underground.
The word cave can also refer to much smaller openings such as sea
caves, rock shelters, and grottos, though strictly speaking a cave is
exogene, meaning it is deeper than its opening is wide, and a rock
shelter is endogene. A cavern is a specific type of cave, naturally
formed in soluble rock with the ability to grow speleothems.
Speleology is the science of exploration and study of all aspects of
caves and the cave environment. Visiting or exploring caves for
recreation may be called caving, potholing, or spelunking.
1 Types and formation
1.1 Solutional cave
1.2 Primary cave
Sea cave or littoral cave
1.4 Corrasional cave or erosional cave
1.5 Glacier cave
1.6 Fracture cave
1.7 Talus cave
1.8 Anchialine cave
2 Physical patterns
3 Geographic distribution
4 Records and superlatives
4.1 World's five longest surveyed caves
6 Archaeological and cultural importance
7 See also
9 External links
Types and formation
The formation and development of caves is known as speleogenesis,
which can occur over the course of millions of years. Caves are
formed by various geologic processes and can be variable sizes. These
may involve a combination of chemical processes, erosion from water,
tectonic forces, microorganisms, pressure, and atmospheric influences.
Isotopic dating techniques can be applied to cave sediments, in order
to determine the timescale when geologic events may have occurred to
help form and shape present day caves.
It is estimated that the maximum depth of a cave cannot be more than
3,000 metres (9,800 ft) due to the pressure of overlying
rocks. For karst caves the maximum depth is determined on the basis
of the lower limit of karst forming processes, coinciding with the
base of the soluble carbonate rocks. Most caves are formed in
limestone by dissolution.
Caves can be classified in various other ways as well, including
active vs. relict; active caves have water flowing through them,
relict caves do not, though water may be retained in them. Types of
active caves include inflow caves ("into which a stream sinks"),
outflow caves ("from which a stream emerges"), and through caves
("traversed by a stream").
Speleothems in Hall of the Mountain King of Ogof Craig a Ffynnon, a
solutional cave in South Wales.
Main article: Solutional cave
Solutional caves or karst caves are the most frequently occurring
caves. Such caves form in rock that is soluble; most occur in
limestone, but they can also form in other rocks including chalk,
dolomite, marble, salt, and gypsum. Rock is dissolved by natural acid
in groundwater that seeps through bedding planes, faults, joints, and
comparable features. Over time cracks enlarge to become caves and cave
The largest and most abundant solutional caves are located in
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 and underground drainage.
Limestone caves are often adorned with calcium carbonate formations
produced through slow precipitation. These include flowstones,
stalactites, stalagmites, helictites, soda straws and columns. These
secondary mineral deposits in caves are called speleothems.
The portions of a solutional cave that are below the water table or
the local level of the groundwater will be flooded.
Lechuguilla Cave in
New Mexico and nearby
Carlsbad Cavern 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
groundwater and forms H2SO4 (sulfuric acid). The acid then dissolves
the limestone from below, rather than from above, by acidic water
percolating from the surface.
Exploring a lava tube in Hawaii.
Caves formed at the same time as the surrounding rock are called
Lava tubes are formed through volcanic activity and are the most
common primary caves. As lava flows downhill, its surface cools and
solidifies. Hot liquid lava continues to flow under that crust, and if
most of it flows out, a hollow tube remains. Examples of such caves
can be found in the Canary Islands, Jeju-do, the basaltic plains of
Eastern Idaho, and other places.
Kazumura Cave near Hilo,
Hawaii is a
remarkably long and deep lava tube; it is 65.6 km long
Lava caves include but are not limited to lava tubes. Other caves
formed through volcanic activity include rift caves, lava mold caves,
open vertical volcanic conduits, and inflationary caves.
Sea cave or littoral cave
Main article: Sea cave
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 5 to
50 metres (16 to 164 ft) in length, but may exceed 300 metres
Corrasional cave or erosional cave
Salt cave in Mount Sodom, Israel.
Corrasional or erosional caves are those that form entirely by erosion
by flowing streams carrying rocks and other sediments. These can form
in any type of rock, including hard rocks such as granite. Generally
there must be some zone of weakness to guide the water, such as a
fault or joint. A subtype of the erosional cave is the wind or aeolian
cave, carved by wind-born sediments. Many caves formed initially by
solutional processes often undergo a subsequent phase of erosional or
vadose enlargement where active streams or rivers pass through them.
Main article: Glacier cave
Glacier cave in Big Four Glacier, Big Four Mountain, Washington, ca.
Glacier caves are formed by melting ice and flowing water within and
under glaciers. The cavities are influenced by the very slow flow of
the ice, which tends to collapse the caves again. Glacier caves are
sometimes misidentified as "ice caves", though this latter term is
properly reserved for bedrock caves that contain year-round ice
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 of stone.
Talus caves are formed by the openings among large boulders that have
fallen down into a random heap, often at the bases of cliffs. These
unstable deposits are called talus or scree, and may be subject to
frequent rockfalls and landslides.
Main article: Anchialine cave
Anchialine 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
Branchwork caves resemble surface dendritic 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.
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.
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.
Spongework caves are formed when solution cavities are joined by
mixing of chemically diverse water. The cavities form a pattern that
is three-dimensional and random, resembling a sponge.
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
Pit caves (vertical caves, potholes, or simply "pits") consist of a
vertical shaft rather than a horizontal cave passage. They may or may
not be associated with one of the above structural patterns.
Cave in Slovak
Caves are found throughout the world, but only a small 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 rough 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 square kilometres
(390,000 sq mi)—has relatively few documented caves.
Records and superlatives
The cave system with the greatest total length of surveyed passage is
Mammoth Cave in Kentucky, US, at 652 km (405 mi).
The longest surveyed underwater cave, and second longest overall, is
Sistema Sac Actun
Sistema Sac Actun in Yucatán, Mexico at 335 km
The deepest known cave — measured from its highest entrance to its
lowest point — is
Krubera Cave in Georgia, with a depth of
2,197 m (7,208 ft). This was the first cave to be
explored to a depth of more than 2 km (1.2 mi). (The first
cave to be descended below 1 km (0.62 mi) was the famous
Gouffre Berger in France.) The Sarma and Illyuzia-Mezhonnogo-Snezhnaya
caves in Georgia, (1,830 m or 6,000 ft, and 1,753 m or
5,751 ft respectively) are the current second- and third-deepest
caves. The deepest outside Georgia is
Weg Schacht in Austria, which is 1,623 m (5,325 ft)
The deepest vertical shaft in a cave is 603 m (1,978 ft) in
Vrtoglavica Cave in Slovenia. The second deepest is Ghar-e-Ghala at
562 m (1,844 ft) in the Parau massif near
The deepest surveyed underwater cave at 404 metres (1,325 ft) is
Hranice Abyss in the Czech Republic.
The largest known room is
Sarawak Chamber, in the Gunung Mulu National
Park (Miri, Sarawak, Borneo, Malaysia), a sloping, boulder strewn
chamber with an area of approximately 700 by 400 m (2,297 by
1,312 ft) and a height of 80 m (260 ft). The nearby
Clearwater Cave System is believed to be the world's largest cave by
volume, with a calculated volume of 3,800,000 m3
(130,000,000 cu ft). The largest room in a show cave is
the salle de La Verna in the French Pyrenees.
The largest passage ever discovered is in the
Son Doong Cave
Son Doong Cave in Phong
Nha-Kẻ Bàng National Park in Quảng Bình Province, Vietnam. It is
4.6 km (2.9 mi) in length, 80 m (260 ft) high and
wide over most of its length, but over 140 m (460 ft) high
and wide for part of its length.
World's five longest surveyed caves
For more, see List of longest caves.
Mammoth Cave, Kentucky, US
Sistema Sac Actun/Sistema Dos Ojos, Mexico
Jewel Cave, South Dakota, US
Sistema Ox Bel Ha, Mexico
Optymistychna Cave, Ukraine
Main article: Biospeleology
Townsend's big-eared bats in a cave in California
Olms in a Slovenian cave
Cave-inhabiting animals are often categorized as troglobites
(cave-limited species), troglophiles (species that can live their
entire lives in caves, but also occur in other environments),
trogloxenes (species that use caves, but cannot complete their life
cycle fully in caves) and accidentals (animals not in one of the
previous categories). Some authors use separate terminology for
aquatic forms (for example, stygobites, stygophiles, and stygoxenes).
Of these animals, the troglobites are perhaps the most unusual
organisms. Troglobitic species often show a number of characteristics,
termed troglomorphic, 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, and cave salamanders such as the olm and the Texas blind
Cave insects such as Oligaphorura (formerly Archaphorura) schoetti are
troglophiles, reaching 1.7 millimetres (0.067 in) 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.
Bats, 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 crickets 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,
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.
Cave entrances often have typical florae. For instance, in the eastern
temperate United States, cave entrances are most frequently (and often
densely) populated by the bulblet fern, Cystopteris bulbifera.
Archaeological and cultural importance
Taíno petroglyphs in a cave in Puerto Rico
Throughout history, primitive peoples have made use of caves. The
earliest human fossils found in caves come from a series of caves near
Krugersdorp and Mokopane in South Africa. The cave sites of
Kromdraai B, Drimolen, Malapa, Cooper's D,
Gladysvale, Gondolin and
Makapansgat have yielded a range of early
human species dating back to between three and one million years ago,
including Australopithecus africanus,
Australopithecus sediba and
Paranthropus robustus. However, it is not generally thought that these
early humans were living in the caves, but that they were brought into
the caves by carnivores that had killed them.
The first early hominid ever found in Africa, the
Taung Child in 1924,
was also thought for many years to come from a cave, where it had been
deposited after being predated on by an eagle. However, this is now
debated (Hopley et al., 2013; Am. J. Phys. Anthrop.). Caves do form in
the dolomite of the Ghaap Plateau, including the Early, Middle and
Later Stone Age site of Wonderwerk Cave; however, the caves that form
along the escarpment's edge, like that hypothesised for the Taung
Child, are formed within a secondary limestone deposit called tufa.
There is numerous evidence for other early human species inhabiting
caves from at least one million years ago in different parts of the
Homo erectus in China at Zhoukoudian, Homo
rhodesiensis in South Africa at the
Cave of Hearths (Makapansgat),
Homo neandertalensis and
Homo heidelbergensis in Europe at
Archaeological Site of Atapuerca,
Homo floresiensis in Indonesia, and
Denisovans in southern Siberia.
In southern Africa, early modern humans regularly used sea caves as
shelter starting about 180,000 years ago when they learned to exploit
the sea for the first time (Marean et al., 2007; Nature). The oldest
known site is PP13B at Pinnacle Point. This may have allowed rapid
expansion of humans out of Africa and colonization of areas of the
world such as Australia by 60-50,000 years ago. Throughout southern
Africa, Australia, and Europe, early modern humans used caves and rock
shelters as sites for rock art, such as those at Giants Castle. Caves
such as the yaodong in China were used for shelter; other caves were
used for burials (such as rock-cut tombs), or as religious sites (such
as Buddhist caves). Among the known sacred caves are China's
Cave of a
Thousand Buddhas and the sacred caves of Crete.
List of caves
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© Oxford University Press 2009
^ Moratto, Michael J. (2014).
California Archaeology. Academic Press.
p. 304. ISBN 9781483277356.
^ Lowe, J. John; Walker, Michael J. C. (2014). Reconstructing
Quaternary Environments. Routledge. pp. 141–42.
^ "Cavern Geology" (PDF). National Caves Association. Retrieved 29
^ a b Laureano, Fernando V.; Karmann, Ivo; Granger, Darryl E.; Auler,
Augusto S.; Almeida, Renato P.; Cruz, Franciso W.; Strícks, Nicolás
M.; Novello, Valdir F. (2016-11-15). "Two million years of river and
cave aggradation in NE Brazil: Implications for speleogenesis and
landscape evolution". Geomorphology. 273: 63–77.
^ authors И. Кудрявцева, Д. Люри. name Geography.
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карстоведения. Д. А. Тимофеев, В. Н.
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Терминология карста. Базис
карстования D.A. Timofeev, V.N. Dublyansky, T.Z. Kiknadze,
Karst Terminology, The Commission
Speleology and Karst, Moscow
Center of the Russian Geographical Society
^ "How Caves Form". Nova (TV series). Retrieved 2013-07-01.
^ Silvestru, Emil (2008). The
Cave Book. New Leaf. p. 38.
^ John Burcham. "Learning about caves; how caves are formed". Journey
into amazing caves. Project Underground. Archived from the original on
May 3, 2009. Retrieved September 8, 2009.
^ a b c d e Easterbrook, Don, 1999, Surface Processes and Landforms
[2nd edition], New Jersey, Prentice Hall, p. 207
^ a b c d e f g World’s Longest Caves List from The National
^ a b c World's Deepest Caves List from The National Speleological
^ Brocklebank, Tony. "Iranian cavers discover one of the world's
deepest shafts". Darkness Below UK. Retrieved 1 January 2017.
^ "Exclusive: Deepest Underwater
^ "Is the Clearwater System the biggest of them all?". The Mulu Caves
Project. Retrieved 19 November 2016.
^ Owen, James (2009-07-04). "World's Biggest
Cave Found in Vietnam".
National Geographic News. National Geographic Society. Retrieved
^ Olsen, Brad (2004). Sacred Places Around the World: 108
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Wikimedia Commons has media related to Caves.
Wikivoyage has travel information for Caves.
Wikisource has the text of the 1920
Encyclopedia Americana article
Cave topics and lists by country
Glossary of caving and speleology
Caves by country
Types and formation
Lists of caves
World Heritage Sites:
Cave Art of Northern Spain
Cave Art of Iberian Mediterranean Basin
Cave Art of the Iberian Southern Tip
New South Wales
Papua New Guinea
Nok and Mamproug