The scientific study of caves is called speleology (from the Greek words spelaion for cave and logos for study). It is a composite science based on geology, hydrology, biology, and archaeology, and thus holds special interest for earth scientists of the U.S. Geological Survey.

The features of a cave are dependent on water action and mineral content. Caves are full of mineral deposits that form unique shapes, such as the icicle-like stalactites (which hang from the ceiling) and stalagmites (which rise up from the ground).

Today, caves are used mainly for scientific research and recreation. Researchers study the underground movement of water through caves to help prevent groundwater wells from becoming polluted. Animals found deep in caves are studied to see how they survive with so little food and no light.

The study of caves is called speleology. A scientist who studies them is a speleologist.

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 of rock and often extend deep underground.

Krubera Cave

Lechuguilla Cave in Carlsbad, New Mexico, is the [deepest cave](https://www.onlyinyourstate.com/usa/three-deepest-caves-in-the-us/) in the United States, extending down 1,604 feet. Surveyors have mapped more than 120 miles of cave passageways.

Lechuguilla Cave

Krubera Cave, also referred to as Voronya Cave, is the world’s deepest (known) cave, located in Abkhazia, Georgia. Exploration has reached as far as 2,197 meters, making it the only cave known to exist on the planet that reaches further than 2,000 meters.

In 2001 a team led by Ukrainian Yuri Kasjan set a world record in the cave of 1,710 meters (5,610 feet). Last July a Moscow-based team extended that to 1,775 meters. Our hope was to find a path past 2,000 meters (6,562 feet).

Cave explorers must be lowered down to its depths and rather than having dry tails like many shallow caves, Krubera has a sump at the bottom, which is basically a water-filled basin.

But most caves form in karst, a type of landscape made of limestone, dolomite, and gypsum rocks that slowly dissolve in the presence of water with a slightly acidic tinge. Rain mixes with carbon dioxide in the atmosphere as it falls to the ground and then picks up more of the gas as it seeps into the soil.

Stalagmites, Stalactites and Columns Stalagmites and stalactites are some of the best known cave formations. They are icicle-shaped deposits that form when water dissolves overlying limestone then re-deposits calcium carbonate along the ceilings or floors of underlying caves.