Caves and Karst

Sponsored by Hoosier NF and Indiana Karst Conservancy. Produced by Ravenswood Media, Inc. Photo Credits: George Cesnik and Keith Pamper, Design and Layout: Kriste Lindberg
	Webumentary - this link leaves the Hoosier NF website but shows actual film footage of cave life done in partnership with the Indiana Karst Conservancy and the Hoosier National Forest. This website also includes other information and interesting facts on caves and karst.
	General Cave and Karst Information
	Inventories for Bats on the Hoosier NF
	Indiana Karst Conservancy receives National Award from Forest Service

Caves and Karst on the Hoosier National Forest

The Hoosier has special underground values that are largely hidden from view and unrecognized by most Forest visitors.  The Forest is located on an area rich in caves and karst features.  Karst is a term that comes from an area in Yugoslavia called the Carso Plateau where scientists first documented these features, and it typically refers to a landscape pockmarked with sinkholes, may be underlain by caves, and has many large springs that discharge into streamvalleys. 

Karst landscapes form when rainwater seeps down through a relatively thin soilcover and into fractured and soluble bedrock.  Weak acids in rainwater that filter down through vegetation and soils easily erode limestone.  The acid slowly dissolves the limestone and creates voids.  These voids gradually enlarge as underground watermoves through them.  Over time, the interaction of water and stone creates blind valleys, caves, gulfs, rises, sinkholes, sinking streams, springs, swallow holes, and other karst features.

Cave environments, by their very nature, provide a unique ecological system.  Indiana has one of the best-known karstareas in the United States.  Well over 100 studies have been published on karst features within the State, many of these in the area of the Forest.  Additionally, caves provide excellent natural classrooms for environmental education of unique underground resources and the interrelationships between the surface and subsurface. 

The karst region in southern Indiana is divided into two parallel areas called the Mitchell Plain (the eastern one third) and the Crawford Upland in the west (Figure 3.24).  The Upland is technically less than 100 feet higher than the plain, so the division is not obvious to most; but underground the rock layers are significantly different.  Layers of rock (limestone, sandstone, and shale) over 400 feet thick were built up by ancient seas that once covered this part of Indiana.  The lowest and thickest layers are limestone up to 170 feet thick.

Over time, massive rock beds tilted and developed cracks and faults.  Erosionhas worn away the upper layers in the Mitchell Plain, exposing the geologically older limestones.  Here the karst features such as sinkholes and disappearing streams are common elements of the landscape.  It is here that towns such as Bedford, Bloomington, Mitchell, and Oolitic developed around the limestone quarry industry.  It is also here one can find the majority of Indiana's 2,500 caves.

Several uncommon plants and animals have at least part, if not all, of their life cycle dependent on the environment provided in caves.  Cave life exists in a finite space without light.  Caves provide air, food, humidity, temperature, and waterin a normally steady state.  Major changes to this delicate environmental balance are disastrous to many of these uncommon plants and animals.  Because caves are dependent on the interaction with the surface, management above ground is important.  Cave ecosystems rely on maintenance of microclimates, prevention of erosionand siltation, soilacidity, and other factors.  Caveenvironments provide habitatfor a considerable number of invertebrate species.  The description and inventory of karstfauna on the Hoosier is a distinctly recent achievement.  Undertaken to acquire baseline inventories, this work continues to describe species new to the scientific literature and to document new distributions of previously described species.  While this work represents a remarkable achievement in the description of karst species and their distribution, science still knows little of their life histories and vulnerabilities.  Due to the extreme isolation and harsh conditions of the cave environment, many of the species, especially cave obligates, are rarely found.

Informational Paper on Caves on the Hoosier