Speleology (fromAncient Greekσπήλαιον (spḗlaion) 'cave' and-λογία (-logía) 'study of') is the scientific study ofcaves and otherkarst features, as well as theircomposition, structure,physical properties, history,ecology, and the processes by which they form (speleogenesis) and change over time (speleomorphology). The termspeleology is also sometimes applied to the recreational activity ofexploring caves, but this is more properly known ascaving,potholing (British English), orspelunking (United States and Canadian English). Speleology and caving are often connected, as the physical skills required forin situ study are the same.

Speleology is a cross-disciplinary field that combines the knowledge ofchemistry,biology,geology,physics,meteorology, andcartography to develop portraits of caves as complex, evolving systems.

Before modern speleology developed,John Beaumont wrote detailed descriptions of someMendip caves in the 1680s. The term speleology was coined byÉmile Rivière in 1890.^[1]

Prior to the mid-nineteenth century the scientific value of caves was considered only in its contribution to other branches of science, and cave studies were considered part of the larger disciplines ofgeography,geology orarchaeology. Very little cave-specific study was undertaken prior to the work ofÉdouard-Alfred Martel (1859–1938), the 'father of modern speleology', who through his extensive and well-publicised cave explorations introduced in France the concept of speleology as a distinct area of study. In 1895 Martel founded theSociété de Spéléologie, the first organization devoted to cave science in the world. Other early speleologists includeHerbert E. Balch.

An international speleological congress was proposed at a meeting inValence-sur-Rhone, France in 1949 and first held in 1953 inParis. TheInternational Union of Speleology (UIS) was founded in 1965.^[2]

The growth of speleology is directly linked with that of the sport ofcaving, both because of the stimulation of public interest and awareness, and the fact that most speleological field-work has been conducted by sportcavers.

Karst is a landscape that has limestone underneath which has been eroded. Caves are usually formed through chemicalcorrosion via a process ofdissolution.^[3] Corrosion has several ways of doing this, it can be on carbonate rocks through chemical reactions, in gypsum and rock salt it can happen physically, and in silicate rocks and warm climate the decomposition of the materials can happen as well.

A speleothem is ageological formation bymineraldeposits that accumulate over time in naturalcaves.^[4] Speleothems most commonly form incalcareous caves due to carbonate dissolution reactions. They can take a variety of forms, depending on their depositional history and environment. Their chemical composition, gradual growth, and preservation in caves make them usefulpaleoclimatic proxies.

Caves have an absence of stabletemperature, high relativehumidity, low rates ofevaporation and limited supply oforganic material, which help in creating an environment which is highly favorable for the growth ofmicrobes. Microbial assemblages in caves includearchaea,bacteria,fungi and other micro-eukaryotes, these highly adapted microbial communities represent the living-backbone of cave ecosystems and play a key role in shaping structures and sustaining trophic networks.^[5]

The creation of an accurate, detailed map is one of the most common technical activities undertaken within a cave. Cave maps, calledsurveys, can be used to compare caves to each other by length, depth and volume, may reveal clues onspeleogenesis, provide a spatial reference for further scientific study, and assist visitors with route-finding.

Caves provide a home for many unique biota. Cave ecologies are very diverse, and not sharply distinct from surface habitats. Generally however, the deeper the cave becomes, the more rarefied the ecology.

Cave environments fall into three general categories:

• Endogean

the parts of caves that are in communication with surface soils through cracks and rock seams, groundwater seepage, and root protrusion.

• Parahypogean

the threshold regions near cave mouths that extend to the last penetration of sunlight.

• Hypogean

or "true" cave environments. These can be in regular contact with the surface via wind and underground rivers, or the migration of animals, or can be almost entirely isolated. Deep hypogean environments can host autonomous ecologies whose primary source of energy is not sunlight, but chemical energy liberated from limestone and other minerals bychemoautotrophic bacteria.

Cave organisms fall into three basic classes:

There are also so-calledaccidental trogloxenes which are surface organisms that enter caves for no survival reason. Some may even betroglophobes (“cave haters”), which cannot survive in caves for any extended period. Examples include deer which fell through a sinkhole, frogs swept into a cave by a flash flood, etc.

The two factors that limit cave ecologies are generally energy and nutrients. To some degree moisture is always available in actively forming Karst caves. Cut off from the sunlight and steady deposition of plant detritus, caves are poor habitats in comparison with wet areas on the surface. Most of the energy in cave environments comes from the surplus of the ecosystems outside. One major source of energy and nutrients in caves is dung from trogloxenes, most of which is deposited by bats. Other sources are mentioned above.^[6]

Cave ecosystems are very fragile. Because of their rarity and position in the ecosystem they are threatened by a large number of human activities. Dam construction, limestone quarrying, water pollution and logging are just some of the disasters that can devastate or destroy underground biological communities.^[7]

Speleologists also work with archaeologists in studying underground ruins, tunnels, sewers and aqueducts, such as the various inlets and outlets of theCloaca Maxima inRome.^[8]

• Different Types of Erosion
• National Speleological Society
• The Virtual Cave, an online guide to speleothems
• Biospeleology; The Biology of Caves, Karst, and Groundwater, by Texas Natural Science Center, theUniversity of Texas at Austin and theMissouri Department of Conservation
• Speleogenesis Network, a communication platform for physical speleology and karst science research
• National Cave Research and Protection Organization, India
• cave-biology.org Cave biology^[usurped], biospeleology inIndia
• Cave Biota; an evolving "webumentary", sponsored byHoosier National Forest and Indiana Karst Conservancy
• IJS – Home Page (International Journal of Speleology) (in English, Italian, French, German, and Spanish)
• Caving News, Daily news and articles on caves, caving, speleology, karst and other information for cavers.