Underneath the rolling hills and glistening streams of Southern Indiana lies an extraordinary world practically unknown to man. The mysterious underground world of caves with their intricate passageways and dramatic formations is a wonderland just waiting to be explored. However, care must be taken not only to protect the animals that rely on these caves, but the citizens who are fortunate to live on this phenomenal landscape known as karst.

You may know what karst is or understand how this type of topography can affect a people, but Karst does matter. It matters a lot.

What is Karst & Where is it in Indiana?

Karst topography is a distinctive type of landscape that is largely shaped by the dissolving action of groundwater on carbonate bedrock, usually limestone. This geological process, which will take thousands of years, is characterized by unique features such as sinkholes, fissures, caves, disappearing streams, springs, rolling topography, and underground drainage systems.

The karst formation process involves what scientists refer to as "the carbon dioxide cascade." As rain falls, it picks up CO2 which dissipates in the droplets. When the rain seeps into the soil, it picks up more carbon dioxide and forms a weak solution on carbonic acid (H2O + CO2 = H2CO3). Over long periods of time, a continuous flow of this acidic water will dissolve carbonate bedrock and create larger openings in cracks and crevices already in the rock. An underground drainage system will eventually from, allowing more water to pass and will lead to the development of caves and other karst formations.

There are two areas of kart landscape in Indiana – the Mitchell Plateau and the Muscatatuck Plateau. Mitchell is located in southern Indiana, extending from eastern Owen County southward towards the Ohio River in Harrison County. Muscatatuck is found in southeastern Indiana. Both were developed by limestone with Mitchell created by Mississippian limestone and Muscatatuck on Silurian and Devonian age bedrock. 

Check out the Indiana Geological Society’s map on the Physiographic Divisions of Indiana to see exactly where these karst regions lie. 

Why Does Karst Matter?

Caves provide essential habitat for unique plants and animals, some of which spend their entire lives in complete darkness - many of them that would not be able to survive otherwise. With our biodiversity at risk, it is important to be careful above and below our karst regions. With some of the species at risk of extinction, it is important to take care when caving as not to disturb what is down below.

Another important reason to be concerned about karst and caved is because these systems carry water from the surface to the underground aquifers where most of our drinking water originates.  In fact, almost 25% of the groundwater is located in caves and karst regions. The protection and management of these vital water resources are critical to public health and to sustainable economic development.  Once a cave is damaged, its formations and the creatures that live within it cannot be recovered. 

Karst systems are critical environmental resources. In fact, 40% of our drinking water passes through cave and karst systems. According the the USGS's Ground Water Resources Program, "the importance of ground-water in complex geologic environments can no longer be overlooked." Karst regions have a unique features that controls the movement and access to ground water and watersheds.  Development in these areas are vulnerable to increased chances of contamination and lack of availability of quality drinking water in the future.

Visit the Karst Waters Institute for more information on the relationship between our drinking water and karst regions.

Trogloxons, Trogophiles and Trogobites, Oh My! 

Cave animals fit into three categories – trogloxenes, trogophiles, troglobites - based on the amount of time they spend in the cave.

Trogloxenes are temporary cave dwellers that come and go freely. Bats - like the Indiana bat - are the most well-known trogloxenes while skunks, raccoons and even humans are other examples.

Troglophiles are animals that love to live in caves but can live outside of them if they choose. Crickets, earthworms, fish and various amphibians are just a few examples.

Troglobites are true cave dwellers; animals that live their entire lives beneath the earth as they can not survive elsewhere. Cave fish, cave crayfish, arthropods, millipedes and some species of salamanders are some examples of these particular cave creatures.

Karst regions and caves accommadate a rich diversity of animals that represent more that half of the endangered species in the United States. Unfortunately less than 4% of these species have any federal protection. That is why many state and local organizations near karst eco-regions - such as The Nature Conservancy and the Indiana Karst Conservancy - have worked hard to protect and preserve our cave systems and the species that rely on them.

What is The Nature Conservancy Doing?

In 2003, TNC’s Indiana Chapter purchased 213 acres of land above the Lost River cave system in Orange County. The Lost River flows down the cave drains 48 square miles of watershed above ground. Chemical pollution, soil run-off and failing septic systems from the area could easily contaminate the water unless the area was protected. The Conservancy hopes that they – along with the U.S. Forest Service and the Indiana Karst Conservancy – will be able to reduce pollutants by protecting what’s on top by limiting access to the property and not allowing new septic systems to be installed. In doing so, The Nature Conservancy will be able to better protect viable populations of cave restricted species and maintain water quality and quantity supplying the karst system.

Indiana’s Blue River Project office works closely with the people who live in the area including the many landowners along the Lost River’s path. Not only are they protecting the cave system but the animals and fauna that need their habitat clean and healthy. Karst plant communities – like limestone glades, chert barrens and upland sinkhole swamps – offer the region a unique beauty not found elsewhere in the state. 

Interesting Facts and Maps 

• Karst habitats comprise 20% of the Earth's land surface.
• One-quarter of the world gets its freshwater from karst aquifers.
• Scientists estimate 60,000 species of cave-dwelling animals worldwide, with 10% in North America.
• An estimated 90% of subterranean life has not yet been described.
• Deforestation, land developments and vandalism are just a few threats to subterranean species.

From TNC’s Subterranean Conservation website

•Caves formed by the "carbon dioxide cascade" are also called solutional caves.  
•Troglobites have developed unique characteristics so they can devote their time to finding food. Most are white or pink in color as they lack pigments and many are “blind” as they have no or poorly developed eyes. Troglobites are usually long in length (compared to their above ground relatives) and can go without food for extreme periods of time
•Speleothem is the general term for any mineral deposit or formation found in caves. The most common are stalactites (which hang from the ceiling) and stalagmites (that grow up from the ground).
 

For More Information

USGS Map of Karst Regions in the United States
The National Karst Map

Indiana Karst Conservancy - "The IKC was formed by concerned individuals when it was apparent that no similar group was actively protecting such features for their inherent geological, biological, and archaeological importance."

Indiana Cave Conservation Association is a small organization who was developed for recreational cave explorers, who wish to our Karst regions for future generations to visit and enjoy.

The mission of the American Cave Conservation Association is to "conserve caves, karstlands and their resources.

Indiana Cave Survey - cavers filling in the need of cataloging all cave and karst features in Indiana.

National Speleological Society - the organization that "does more than any other organization to study, explore, and conserve cave and karst resources; protect access to caves; encourage responsible management of caves and their unique environments; and promote responsible caving."

Serving the Cavers of Indiana -  Indiana Caver  
The Indiana Outfitter's offer a listing of where to go for your caving needs.

USGS Karst Hydrology Map
Tips on how to prevent ground water contimination in karst regions by the Indiana Geological Society.

The National Park Services Cave and Karst Program

National Caves and Karst Management Symposium - forums for promoting, advancing, and sharing concepts in effective management of cave and karst resources. Check out their paper on the misconceptions about caves and karst.

Links for Teachers on Karst and Caves:
USGS Teacher's Guide and Paper Model Instructions

Fun Experiments for Kids:  
Karst Topography Simulation
Sinkholes in a Cup

Conservation of the North American Cave and Karst Biota - a paper by William R. Elliot, 1998

Nature picture credits (top to bottom, left to right): Photo © TNC (cave); Graphic © Elena Blando (karst map).