Cave geology

thumb|Cenote at Hubiku, Yucatan

natural conduits through which lava travels beneath the surface of a lava flow

thumb|Eternal Flame Falls in New York has an eternal flame inside a small grotto behind the falls thumb|Grutas de García in [[Nuevo León, Mexico]]

marine sinkhole or cavern

area in an aquifer, below the water table

Suffosion is one of the two geological processes by which subsidence sinkholes or dolines are formed, the other being due to collapse of an underlying cave or void, with most sinkholes formed by the suffosion process. Suffosion sinkholes are normally associated with karst topography although they may form in other types of rock including chalk, gypsum and basalt. In the karst of the UK's Yorkshire Dales, numerous surface depressions known locally as "shakeholes" are the result of glacial till washing into fissures in the underlying limestone.

geological phenomenon, holes in coastal rock formations through which sea water is forced by the tide or waves.

crystal whose faces are easily distinguishable

Phreatic is a term used in hydrology to refer to aquifers, in speleology to refer to cave passages, and in volcanology to refer to a type of volcanic eruption.

thumb|Creux-Genat, an intermittent karst estavelle between Chevenez and Porrentruy in the Ajoie, recorded on April 2nd, 2005 and April 17th, 2006. In karst geology, estavelle or inversac is a ground orifice which, depending on weather conditions and season, can serve either as a sink or as a source of fresh water. It is a type of ponor or sinkhole.

Speleogenesis is the origin and development of caves, the primary process that determines essential features of the hydrogeology of karst and guides its evolution. It often deals with the development of caves through limestone, usually caused by the presence of water with carbon dioxide dissolved within it, producing carbonic acid which permits the dissociation of the calcium carbonate in the limestone.