Karst is a term used to describe a special type of landscape that is formed by the dissolution of soluble rocks, including limestone and dolomite. Karst landscapes are often spectacularly scenic areas. The topography of such areas is dominated by sinkholes, sinking streams, large springs, and caves.

Karst regions contain aquifers that provide large supplies of water. More than 25 percent of the world's population either lives on or obtains its water from karst aquifers. In the United States, 20 percent of the land surface is karst and 40 percent of the groundwater used for drinking comes from karst aquifers.

In cave and karst regions the relationship between groundwater and surface water is easily recognized. Sizable surface streams disappear into underground channels and conversely, some large springs emerge to become the headwaters for rivers. The sinkholes and cave entrances are direct openings to the groundwater, acting much like a kitchen sink drain, allowing anything running off the surface land area to enter the groundwater. This makes a tremendous groundwater pollution potential in karst areas. Groundwater can travel quite rapidly through these underground networks - up to several miles a day - and contaminants can be transmitted quickly to wells and springs in the vicinity.

Many homeowners believe that the source of their groundwater is miles away, and is naturally protected from surface activities. In reality, water quality monitoring projects in karst areas have documented that water often comes directly from the immediate surface.

Groundwater is a precious, non renewable resource, and polluting our groundwater will start to impact everyone.

Another division of cave habitats is by light zone. The area just inside the cave opening is called the entrance zone. This area inside the cave still receives sun light. The light from the entrance allows some plant growth and an exchange of animals that might commonly be seen living above ground. Farther from the entrance the light begins to diminish. This area is called the twilight zone. The dark zone begins where the cave becomes completely dark and extends throughout the rest of the cave.

Compared to surface habitats, underground habitats are food-poor. Most of the nutrients must be brought into the cave from outside. This occurs by organic debris, seeds, nuts and small animals being carried into the cave by flowing water. Organic matter is also carried into the cave by organisms in the form of eggs and guano (feces). Additionally insects and other animals dying inside the cave become food for other cave animals. All the organic matter is decomposed (broken down) by molds, fungi and bacteria. The nutrients then become available to microscopic animals and insects which in turn are eaten by larger animals. The karst species are adapted to live on this limited food supply.

A large variety of animals live in caves. Species who spend their entire life in a cave’s total darkness must be adapted to the continuous darkness, and usually constant temperatures and high humidity. The adaptations include lack of pigmentation, increased sensory structures, reduced eyes or blindness, low reproductive rates and elongated appendages and antennae.

There are degrees of adaptation in cave life. Adaptation is relatively slight in animals that live in caves for short periods of time. Biologists classify cave animals based on the animal’s degree of adaptation, its cave habitat, and the amount of time it spends in the cave environment.

Terrestrial cave dwelling species live on land and have the prefix Troglo. Aquatic cave dwelling species live in the water and have the prefix Stygo.

Caves have captured the imagination of many poets and authors, and have conjured the spirit of adventure and exploration. Human use of caves has come a long way throughout our history, from living space to hiding place and from commercial production to exploration. Despite the long existence of caves, we continue to learn from them and about them.

Caves are a valuable source for information about both the geological and historical past. Fossils found in caves provide paleontologists with clues to the biological portion of the earth's history. Fossils of marine animals and plants that lived in the seas where the limestone was deposited are found imbedded in the bedrock. In addition, fossils of more recent terrestrial creatures which used the caves as homes or became trapped in sinkholes are sometimes found in cave passages. These include mammoth, mastodon, saber tooth cat, and giant sloth remains.

Records of past human civilizations are found as cave artifacts, ranging from cave paintings and pottery of native and ancient peoples to the remnants of saltpeter mining from the American Civil War. The dry, nearly constant atmosphere of many caves has preserved the artifacts. Primitive tools, clothing, food, artwork, and skeletal remains of humans and animals all provide needed clues to our past. We also know that early humans used the entrances of caves for living spaces.

Caves were often used for very practical reasons. In recent centuries, modern humans used caves for purposes such as storing fruits and vegetables and for growing mushrooms. History shows that the darkness and constant temperatures provide ideal conditions for the aging processes of some cheeses and alcoholic beverages. Some caves were used as hospitals for people with respiratory illnesses in hope that the constant atmosphere might help. Caves have provided hiding places for bandits, smugglers, counterfeiting operations, and moonshining (making illegal whiskey). Cave waters have supplied a ready source of water for making many kinds of products. Caves have also been mined for guano (bat feces), used as fertilizer through the late 1940's.

Today we understand the great value caves have to offer. Scientists study the natural resources in the caves and karst areas. This research ranges from studying the habitats of the many species of cave adapted animals to better understanding how caves were formed. Hydrologists study the water and the interactions between surface water and groundwater in cave areas. These studies will lead to a better understand of the natural resources that are important to everyday life. This knowledge can then be used for management plans to protect these valuable natural resources for future generations.