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A cave or cavern is a natural void in the
ground Ground may refer to: * Soil File:Stagnogley.JPG, Surface-water-Gley soil, gley developed in glacial till, Northern Ireland. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body ...

ground
, specifically a space large enough for a human to enter. Caves often form by the
weathering Weathering is the deterioration of Rock (geology), rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little o ...
of rock and often extend deep underground. The word ''cave'' can also refer to much smaller openings such as
sea cave A sea cave, also known as a littoral cave, is a type of cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering Weathering is the breaking down of roc ...
s,
rock shelter A rock shelter (also rockhouse, crepuscular cave, bluff shelter, or abri) is a shallow cave-like opening at the base of a bluff or cliff. In contrast to solutional caves (karst Karst is a topography formed from the dissolution of solub ...

rock shelter
s, and
grotto A grotto is a natural or artificial cave A cave or cavern is a natural void in the Earth#Surface, ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. ...

grotto
s, though strictly speaking a cave is exogene, meaning it is deeper than its opening is wide, and a rock shelter is endogene.
Speleology Speleology is the scientific study of cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering Weathering is the breaking down of rocks, soil Soi ...
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''.


Formation types

The formation and development of caves is known as ''
speleogenesisSpeleogenesis is the origin and development of cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering Weathering is the breaking down of rocks, soil S ...
''; it can occur over the course of millions of years. Caves can range widely in size, and are formed by various geological processes. These may involve a combination of chemical processes, erosion by water, tectonic forces, microorganisms, pressure, and atmospheric influences. Isotopic dating techniques can be applied to cave sediments, to determine the timescale of the geological events which formed and shaped present-day caves. It is estimated that a cave cannot be more than vertically beneath the surface due to the pressure of overlying rocks. This does not, however, impose a maximum depth for a cave which is measured from its highest entrance to its lowest point, as the amount of rock above the lowest point is dependent on the topography of the landscape above it. For
karst Karst is a topography Topography is the study of the forms and features of land surfaces. The topography of an area could refer to the surface forms and features themselves, or a description (especially their depiction in maps). Topography ...

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 Limestone is a common type of carbonate In chemistry, a carbonate is a salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its na ...

limestone
by
dissolution Dissolution may refer to: Arts and entertainment Books * Dissolution (Forgotten Realms novel), ''Dissolution'' (''Forgotten Realms'' novel), a 2002 fantasy novel by Richard Lee Byers * Dissolution (Sansom novel), ''Dissolution'' (Sansom novel), a 2 ...

dissolution
. Caves can be classified in various other ways as well, including a contrast between active and 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").


Solutional

Solutional caves or karst caves are the most frequently occurring caves. Such caves form in rock that is soluble; most occur in
limestone Limestone is a common type of carbonate In chemistry, a carbonate is a salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of Salt (chemistry), salts; salt in its na ...

limestone
, but they can also form in other rocks including
chalk Chalk is a soft, white, porous Porosity or void fraction is a measure of the (i.e. "empty") spaces in a , and is a of voids over the total volume, between 0 and 1, or as a between 0% and 100%. Strictly speaking, some tests measure the "acce ...

chalk
,
dolomiteDolomite may refer to: *Dolomite (mineral) Dolomite () is an anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and ...
, marble, salt, and
gypsum Gypsum is a soft sulfate mineral The sulfate minerals are a class of mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with ...

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 systems. 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 In chemistry, carbonic acid is a dibasic acid with the chemical formula A chemical formula is a way of presenting information about the chemical proportions of atom An atom is the smallest unit of ordinary matter In classical ...

carbonic acid
) and naturally occurring
organic acid An organic acid is an with ic properties. The most common organic acids are the s, whose acidity is associated with their  –COOH. s, containing the group –SO2OH, are relatively stronger acids. Alcohols, with , can act as acids but t ...
s. The dissolution process produces a distinctive landform known as ''
karst Karst is a topography Topography is the study of the forms and features of land surfaces. The topography of an area could refer to the surface forms and features themselves, or a description (especially their depiction in maps). Topography ...

karst
'', characterized by
sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as vrtače and shakeholes, and to openings ...

sinkhole
s and underground drainage. Limestone caves are often adorned with
calcium carbonate Calcium carbonate is a chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entity, molecular entities) composed of atoms from more than one chemical element, element held togethe ...

calcium carbonate
formations produced through slow precipitation. These include
flowstone Flowstones are composed of sheetlike deposits of calcite Calcite is a carbonate mineral Carbonate minerals are those mineral In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", ...
s,
stalactite A stalactite (, ; from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population ...

stalactite
s,
stalagmite A stalagmite (, ; from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its populati ...

stalagmite
s,
helictite A helictite is a speleothem A speleothem (; from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in South ...
s,
soda straw Soda or SODA may refer to: Chemistry * Some chemical compounds containing sodium ** Sodium carbonate, washing soda or soda ash ** Sodium bicarbonate, baking soda ** Sodium hydroxide, caustic soda ** Sodium oxide, an alkali metal oxide * Sod ...
s and columns. These secondary mineral deposits in caves are called ''
speleothem A speleothem (; from Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is ap ...
s''. The portions of a solutional cave that are below the
water table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. Th ...

water table
or the local level of the groundwater will be flooded.
Lechuguilla Cave At , Lechuguilla Cave is the eighth-longest explored cave in the world and the second deepest () in the continental United States. It is most famous for its unusual geology, rare speleothem, formations, and pristine condition. The cave is named ...
in
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Greater Albuquerque , OfficialLang = None , Languages = English English usually refer ...

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 Hydrogen sulfide is a chemical compound A chemical compound is a chemical substance A chemical substance is a form of matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by havi ...

hydrogen sulfide
) gas rising from below, where reservoirs of oil give off sulfurous fumes. This gas mixes with groundwater and forms H2SO4 (
sulfuric acid Sulfuric acid (American spelling Despite the various English dialects spoken from country to country and within different regions of the same country, there are only slight regional variations in English orthography English orthogra ...

sulfuric acid
). The acid then dissolves the limestone from below, rather than from above, by acidic water percolating from the surface.


Primary

Caves formed at the same time as the surrounding rock are called primary caves.
Lava tube , California shows the classic tube shape; the grooves on the wall mark former flow levels. , Hawaii. The step mark, more visible on the right wall, indicates the depth at which the lava flowed for a period of time. . This is the Manjanggul lava pil ...

Lava tube
s are formed through
volcanic A volcano is a rupture in the crust of a planetary-mass object A planet is an astronomical body orbit In physics, an orbit is the gravitationally curved trajectory of an physical body, object, such as the trajectory of a planet ar ...

volcanic
activity and are the most common primary caves. As
lava Lava is magma once it has been expelled from the interior of a terrestrial planet (such as Earth) or a Natural satellite, moon onto its surface. Lava may be erupted at a volcano or through a Fissure vent, fracture in the Crust (geology), crust, ...

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. Such caves can be found in the
Canary Islands The Canary Islands (; es, Islas Canarias, ), also known informally as ''the Canaries'', is a Spanish archipelago An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster or collection of island ...
,
Jeju-do Jeju Island (; ) is the largest island in South Korea South Korea, officially the Republic of Korea (ROK), is a country A country is a distinct territory, territorial body or political entity. It is often referred to as the lan ...
, the basaltic plains of
Eastern Idaho Eastern Idaho is the area of Idaho Idaho () is a in the region of the United States. It borders the state of to the east and northeast, to the east, and to the south, and and to the west. To the north, it shares a small portion of ...
, and in other places.
Kazumura Cave Kazumura Cave is a lava tube and has been surveyed at 40.7 miles (65.5 km) long and 3,614 feet (1,102 m) deep making it the longest and deepest lava tube in the world. The cave is located on the island of Hawaii (island), Hawaiʻi on the easter ...
near
Hilo Hilo () is a census-designated place (CDP) and the largest city in Hawaii County, Hawaii, Hawaii County, Hawaii, United States, which encompasses the Hawaii (island), Island of Hawaii. The population was 44,186 according to the 2020 United State ...

Hilo
,
Hawaii Hawaii ( ; haw, Hawaii or ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspape ...
is a remarkably long and deep lava tube; it is . Lava caves include but are not limited to lava tubes. Other caves formed through volcanic activity include rifts, lava molds, open vertical conduits, inflationary, blisters, among others.


Sea or littoral

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 Ko Tapu, also known as James Bond Island, Phang Nga Bay Phang Nga Bay ( th, อ่าวพังงา, , ) is a 400 km2 bay in the Strait of Malacca between the island of Phuket Province, Phuket and the mainland of the Kra Isthmus of south ...

Phang Nga Bay
, solutional caves have been flooded by the sea and are now subject to littoral erosion. Sea caves are generally around in length, but may exceed .


Corrasional or erosional

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.


Glacier

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 cave water ice inside an ice cave An ice cave is any type of natural cave A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering Weathering is the breaking do ...

ice cave
s", though this latter term is properly reserved for bedrock caves that contain year-round ice formations.


Fracture

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

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 Scree is a collection of broken rock Rock most often refers to: * Rock (geology) A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound ...

scree
, and may be subject to frequent
rockfall A rockfall or rock-fallWhittow, John (1984). ''Dictionary of Physical Geography''. London: Penguin, 1984. . refers to quantities of rock falling freely from a cliff upEurope's highest cliff, Troll Wall in Norway, a famous BASE jumping loc ...
s and
landslide Landslides, also known as landslips, are several forms of mass wasting Mass wasting, also known as mass movement, is a general term for the movement of rock Rock most often refers to: * Rock (geology) A rock is any naturally occurri ...

landslide
s.


Anchialine

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 fauna.


Physical patterns

*''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
sinkhole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as vrtače and shakeholes, and to openings ...

sinkhole
s where
groundwater recharge Groundwater recharge or deep drainage or deep percolation is a process, where moves downward from to . Recharge is the primary method through which water enters an . This process usually occurs in the below plant s and, is often expressed as ...
occurs. Each passage or branch is fed by a separate recharge source and converges into other higher order branches downstream.Easterbrook, Don, 1999, ''Surface Processes and Landforms nd edition', New Jersey, Prentice Hall, p. 207 *''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 water. *''
Pit cave A pit cave, shaft cave or vertical cave—or often simply called a pit (in the US) or pot (in the UK); jama in South Slavic languages scientific and colloquial vocabulary (borrowed since early research in the Western Balkan Dinaric Alpine karst ...
s'' (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.


Geographic distribution

Caves are found throughout the world, although the distribution of documented cave system is heavily skewed towards those 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 The Madagascar dry deciduous forests represent a tropical and subtropical dry broadleaf forests, tropical dry forest ecoregion situated in the western and northern part of Madagascar. The area has high numbers of Endemism, endemic plant and animal ...
and parts of
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At 8.5 million square kilometers (3.2 million square miles) and with over 211 mill ...

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 —has relatively few documented caves.


Records and superlatives

*The cave system with the ''greatest total length'' of surveyed passage is in
Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ...
, US, at .World’s Longest Caves List from The National Speleological Society
/ref> *The longest surveyed ''underwater cave'', and second longest overall, is
Sistema Sac Actun Sistema Sac Actun (from Spanish and Yucatec Maya meaning "White Cave System") is an underwater cave system situated along the Caribbean coast of the Yucatán Peninsula The Yucatán Peninsula (, also , ; es, Península de Yucatán), in southea ...
in
Yucatán Yucatán (, also , , ; yua, Yúukatan ), officially the Free and Sovereign State of Yucatán,; yua, link=no, Xóot' Noj Lu'umil Yúukatan. is one of the 32 states which comprise the political divisions of Mexico, Federal Entities of Mexico. I ...

Yucatán
, Mexico at . *The ''deepest known cave'' — measured from its highest entrance to its lowest point — is
Veryovkina Cave Veryovkina Cave (also spelled Verëvkina Cave, , , ) is deep, the deepest-known cave on Earth. Its entrance is situated above sea level in Abkhazia, Georgia (country), Georgia. The entrance of the cave has a cross section of , and is located in ...
in
Abkhazia Abkhazia, , ka, აფხაზეთი, , rus, Абха́зия, r=Abkhaziya, p=ɐˈpxazʲɪjə xmf, აბჟუა, or , ( or ) is a partially recognized state in the South Caucasus Transcaucasia, also known as the South Caucasus, ...

Abkhazia
,
Georgia Georgia usually refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), one of the states of the United States of America Georgia may also refer to: Historical states and entities * Democratic Republ ...
, with a depth of .World's Deepest Caves List from The National Speleological Society
/ref> This was the first cave to be explored to a depth of more than . (The first cave to be descended below was
Gouffre Berger The Gouffre Berger is a French cave discovered on 24 May 1953 by Joseph Berger, Bouvet, Ruiz de Arcaute and Marc Jouffray. From 1953 to 1963, it was regarded as the deepest cave in the world at , relinquishing this title to the previous contender, ...

Gouffre Berger
in France.) The Sarma and Illyuzia-Mezhonnogo-Snezhnaya caves in Georgia, (, and respectively) are the current second- and third-deepest caves. The deepest outside Georgia is Lamprechtsofen Vogelschacht Weg Schacht in Austria, which is deep. *The ''deepest vertical shaft'' in a cave is in Vrtoglavica Cave in
Slovenia Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. It is bordered by Italy Italy ( it, Italia ), officially the Italian Republic ( it, Repubblica Italiana, l ...

Slovenia
. The second deepest is Ghar-e-Ghala at in the Parau massif near
Kermanshah Kermanshah ( fa, ; ku, Kirmaşan ,کرماشان), also known as Kermāshān, is the capital of Kermanshah Province#REDIRECT Kermanshah Province Kermanshah Province ( fa, استان كرمانشاه, Ostān-e Kermanšah, ku, پارێزگا ...

Kermanshah
in
Iran Iran ( fa, ایران ), also called Persia, and officially the Islamic Republic of Iran, is a country in Western Asia Western Asia, West Asia, or Southwest Asia, is the westernmost subregion A subregion is a part of a larger regio ...

Iran
. * The deepest ''underwater cave'' bottomed by a
remotely operated underwater vehicle A remotely operated underwater vehicle (technically ROUV or just ROV) is a tether A tether is a cord, fixture, or flexible attachment that characteristically anchors something movable to something fixed; it also maybe used to connect two movabl ...
at , is the
Hranice Abyss The Hranice Abyss ( cs, Hranická propast, the English name adopted by the local tourist authorities) is the deepest pit cave in the Czech Republic flooded pit cave in the world. It is a karst sinkhole located near the town of Hranice (Přerov Dis ...
in the
Czech Republic The Czech Republic, also known by its short-form name Czechia and formerly known as Bohemia, is a landlocked country in Central Europe. It is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to ...
. *The ''largest known room'' is
Sarawak ChamberSarawak Chamber is the largest known cave chamber in the world by area and the second largest by volume after the Miao Room in China. It is in Gua Nasib Bagus (Good Luck Cave), which is located in Gunung Mulu National Park, in the Malaysian state of ...
, in the
Gunung Mulu National Park The Gunung Mulu National Park is a national park in Miri Division, Sarawak, Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, t ...
( Miri,
Sarawak Sarawak (; ) is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ''The State'' (newspaper), a daily newspaper i ...

Sarawak
,
Borneo Borneo (; id, Kalimantan) is the third-List of islands by area, largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java Is ...

Borneo
,
Malaysia Malaysia ( ; ) is a country in Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is the geographical southeastern subregion of Asia, consisting of the regions ...

Malaysia
), a sloping, boulder strewn chamber with an area of approximately and a height of . The nearby Clearwater Cave System is believed to be the world's ''largest cave by volume'', with a calculated volume of . The largest room in a
show cave A show cave — also called tourist cave, public cave, and in the United States, commercial cave — is a cave which has been made accessible to the public for guided visits. Definition File:Manjanggul Lava tube.jpg, Lighting in Manjanggul l ...
is the salle de La Verna in the French
Pyrenees The Pyrenees (; es, Pirineos ; french: Pyrénées ; ca, Pirineus ; eu, Pirinioak ; oc, Pirenèus ; an, Pirineus) is a mountain range straddling the border of France and Spain. It extends nearly from its union with the Cantabrian Mountains to ...

Pyrenees
. *The ''largest passage'' ever discovered is in the Son Doong Cave in
Phong Nha-Kẻ Bàng National ParkPhong may refer to: Computer graphics *Phong shading *Phong reflection model The Phong reflection model (also called Phong illumination or Phong lighting) is an empirical model of the illumination model, local illumination of points on a Surface ...
in
Quảng Bình Province Quảng Bình (), formerly Tiên Bình under the reign of Lê Trung Hưng of the Lê dynasty (this province was renamed Quảng Bình in 1604), is a Provinces of Vietnam, province along North Central Coast, Vietnam's north-central coast. The provi ...
,
Vietnam Vietnam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,, group="n" is a country in Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia or SEA, is the ...

Vietnam
. It is in length, high and wide over most of its length, but over high and wide for part of its length.


Five longest surveyed

# Mammoth Cave,
Kentucky Kentucky ( , ), officially the Commonwealth of Kentucky, is a state State may refer to: Arts, entertainment, and media Literature * ''State Magazine'', a monthly magazine published by the U.S. Department of State * The State (newspaper), ...
, US #
Sistema Sac Actun Sistema Sac Actun (from Spanish and Yucatec Maya meaning "White Cave System") is an underwater cave system situated along the Caribbean coast of the Yucatán Peninsula The Yucatán Peninsula (, also , ; es, Península de Yucatán), in southea ...
/
Sistema Dos Ojos Dos Ojos (from Spanish language, Spanish meaning "Two Eyes"; officially Sistema Dos Ojos) is part of a flooded cave system located north of Tulum, on the Caribbean coast of the Yucatán Peninsula, in the state of Quintana Roo, Mexico. The explorati ...
, Mexico # Jewel Cave,
South Dakota South Dakota () (Sioux The Sioux or Oceti Sakowin (; Dakota Dakota may refer to: * Dakota people, a sub-tribe of the Sioux ** Dakota language, their language From this origin, Dakota may also refer to: Places United States * Dako ...

South Dakota
, US #
Sistema Ox Bel Ha Sistema Ox Bel Ha (from Yucatec Maya language, Mayan meaning "Three Paths of Water"; short Ox Bel Ha) is a cave system in Quintana Roo, Mexico. It is the longest explored underwater cave in the world and ranks fourth including dry caves. As of May ...
, Mexico # Optymistychna Cave,
Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in . It is the in Europe after , which it borders to the east and north-east. Ukraine also shares borders with to the north; , , and to the west; and to the south; and has a coastli ...

Ukraine


Ecology

Cave-inhabiting animals are often categorized as
troglobite A troglobite (or, formally, troglobiont) is an animal species, or population of a species, strictly bound to underground habitats, such as caves. These are separate from species that mainly live in above-ground habitats but are also able to live u ...
s (cave-limited species),
troglophile Troglofauna are small cave-dwelling animals that have adaptation, adapted to their dark surroundings. Troglofauna and stygofauna are the two types of subterranean fauna (based on life-history). Both are associated with subterranean environments – ...
s (species that can live their entire lives in caves, but also occur in other environments),
trogloxeneTrogloxenes or subtroglophiles, also called cave guests, are animal species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species i ...
s (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,
stygobite Stygofauna are any fauna that live in groundwater systems or aquifers, such as caves, fissures and vugs. Stygofauna and troglofauna are the two types of subterranean fauna (based on life-history). Both are associated with subterranean environments ...
s, 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 salamander A cave salamander is a type of salamander that primarily or exclusively inhabits caves, a group that includes several species. Some of these animals have developed special, even extreme, adaptations to their subterranean environments. Some speci ...
s such as the
olm The olm or proteus (''Proteus anguinus'') is an aquatic in the family , the only species found in Europe. In contrast to most s, it is entirely ; it eats, sleeps, and breeds underwater. Living in caves found in the , it is to the waters th ...

olm
and the .
Cave insects Cave dwelling insects are among the most widespread and prominent troglofauna (cave-dwelling animals), including Troglofauna#Categories, troglobites, Troglofauna#Categories, troglophiles, and Troglofauna#Categories, trogloxenes. As a category of ec ...
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 in 1969.
Bat Bats are mammal Mammals (from Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as Latium. Through the po ...

Bat
s, such as the
gray bat The gray bat (''Myotis grisescens'') is a species of microbat endemic to North America. The creature once flourished in caves all over the southeastern United States The southeastern United States, also referred to as the American Southeast ...
and
Mexican free-tailed bat The Mexican free-tailed bat or Brazilian free-tailed bat (''Tadarida brasiliensis'') is a medium-sized bat native to the Americas, regarded as one of the most abundant mammals in North America. Its proclivity towards roosting in huge numbers at ...
, 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 fragility of cave ecosystems, 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. 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

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 Sterkfontein, Swartkrans, 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 world, including ''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 the 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, Buddhist caves). Among the known sacred caves are China's Cave of a Thousand Buddhas and the sacred caves of Crete.


Caves and acoustics

The importance of sound in caves predates a modern understanding of acoustics. Archaeologists have uncovered relationships between paintings of dots and lines, in specific areas of resonance, within the caves of Spain and France, as well as instruments depicting paleolithic motifs, indicators of musical events and rituals. Clusters of paintings were often founds in areas with notable acoustics, sometimes even replicating the sounds of the animals depicted on the walls. The human voice was also theorized to be used as an echolocation device to navigate darker areas of the caves where torches were less useful. Dots of red ochre are often found in spaces with the highest resonance, where the production of paintings was too difficult. Here, singing is to be the most efficient way to explore caves. Caves continue to provide usage for modern-day explorers of acoustics. Today Cumberland Caverns provides one of the best examples for modern musical usages of caves. Not only are caves utilized for the reverberations, but for the dampening qualities of their abnormal faces as well. The irregularities in the walls of the Cumberland Caverns diffuse sounds bouncing off the walls and give the space and almost recording studio-like quality. During the 20th century musicians began to explore the possibility of using caves as locations as clubs and concert halls, including the likes of Dinah Shore, Roy Acuff, and Benny Goodman. Unlike today, these early performances were typically held in the mouths of the caves, as the lack of technology made depths of the interior inaccessible with musical equipment. In Luray Caverns, Virginia, a functioning organ (music), organ has been developed that generates sound by mallets striking stalactites, each with a different pitch.


See also

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References

{{Authority control Caves, Erosion landforms Fluvial landforms