What Are Caves?

Speleologists (or cave scientists) consider South Dakota to be one of the premier cave regions of the world! Located beneath
South Dakota are some of the world's largest and most interesting caves. These caves are useful to both wildlife and humans alike.

Most of the caves in South Dakota are formed in limestone. Limestone is a sedimentary rock made of the shells and skeletons of animals which lived in seas that covered this state long ago. Limestone dissolves more easily in water than most rocks. If water enters cracks in limestone, it dissolves away the rocks and enlarges the cracks. If the cracks become large enough for humans to enter, we call them caves. Other types of caves exist, but none is as important to South Dakota, environmentally or economically, as limestone caves.

Figure 1. Paha Sapa Limestone outcrop belt where S.D. Caves can be found. 
Where Are They Found?

All of South Dakota's limestone caves are found in or near the Black Hills. This is the only part of the state where limestone
is found at the surface. The layer of limestone containing most of these caves is called the Paha Sapa limestone. This rock
formation was deposited in a shallow sea between 330 and 360 million years ago. Pahasapa limestone deposits vary from
300 to 600 feet in thickness.

More than 100 caves have been explored in the limestone surrounding the Black Hills. Many of these caves are only a few
hundred feet or less in length. Some are much longer. Jewel Cave, discovered west of the city of Custer in 1900, contains
more than 84 miles of passages. This makes Jewel Cave the second longest cave in the United States (only Mammoth Cave in Kentucky is longer) and the fourth longest cave in the world. Wind Cave, discovered north of Hot Springs in 1881, is more
than 65 miles in length. Wind Cave is the third longest cave in the United States and the seventh longest in the world. Studies
of the wind, which is always present at the cave entrances, indicate that less than 5% of both Jewel Cave and Wind Cave
have been explored! These calculations are based on measurements of the volume of air entering and leaving the cave and the resulting estimation of the cave volume to be 2 billion cubic feet. 


Black Hills caves are interesting for more than just their size. Most geologists consider the caves of the Black Hills to be
among the world's oldest. Wind and Jewel Caves are thought to have begun forming 40 to 60 million years ago. Some Black
Hills caves are home to certain types of cave formations that are found in few other caves in the world. Wind Cave, for
example, contains more displays of a formation known as boxwork than any other cave in the world. Some of the caves in the
Black Hills have been developed to allow easy access for humans. Trails have been constructed to make walking easier, and
electric lights have been installed to illuminate the caves, which are naturally very dark. For a fee, visitors are taken through
the cave by someone who knows the way. There are currently eight caves in the Black Hills that offer tours.

Why Are Caves Important?

Wildlife Habitat:
Caves are a valuable habitat for a variety of animals. Most caves have remarkably constant temperatures. This makes them
attractive to animals such as bats, who often use caves for hibernation. Bats also roost in caves during the day and use them
as nurseries for their young. Some caves, such as Wind Cave, have few bats. Other caves, especially Jewel Cave, house
thousands of bats at some times of the year. Bats have developed a bad reputation over the years. This is unfortunate, because
bats are extremely important to the environment as important predators of insects.

Caves are dark places. This makes it impossible for plants to grow in caves. Without plants, there is very little food
available for animals to live off of. Because of this, the number of animals living in caves is relatively small. The ones that
do live there are often highly adapted to the special cave environment. For example, many are blind, since there is little use
for sight in a perfectly dark cave. A number of caves in the Black Hills contain species of blind insects. Some of these
species, such as a springtail found in Wind Cave, may be unique to Black Hills caves!

Human Shelter:
Caves are valuable to humans as well. Some caves in the Black Hills served as shelter for thousands of years. Others may
have religious significance to local Native Americans.

Scientific Study:
Caves serve as important natural laboratories where scientists may study simple ecosystems. By understanding these simple
ecosystems, we may be able to gain a better understanding of life on the surface of our planet. Caves also provide unique
opportunities for geologists to study groundwater or rare minerals.

Caves are economically important to the Black Hills region. Each year, millions of dollars are spent by the visitors to the
developed caves.

Conservation Measures

Things work very slowly in caves. A careless action, such as breaking a formation or disturbing a cave's native animals, can
undo thousands of years of nature's work. As far as humans are concerned, once a cave is changed, it is changed forever. For
this reason alone, we must work to preserve caves wherever they are found.

Caves on federal lands are now protected by law. Both Jewel Cave and Wind Cave are administered by the National Park
Service. The Federal Cave Resources Protection Act of 1988 requires government agencies such as the United States Forest
Service, Bureau of Land Management, and National Park Service to protect the significant caves contained on the lands they
administer. This act makes it a crime to disturb any of the features of caves found on federal land. Several states also have
cave protection laws. South Dakota currently has no laws directly devoted to the protection of caves.


Boxwork - an unusual formation, resulting from weathering, that is composed of thin, intersecting blades of calcite.
Limestone - a sedimentary rock consisting mainly of calcium carbonate crystals. This rock is formed by the accumulated deposits of dead invertebrates.
Sedimentary rock - one of the major types of rocks; formed from the matter that settles to the bottom of a body of water.
Speleology - the science of exploring caves.
Spelunker - one whose hobby it is to explore caves.

Reference Materials

Moore, G.W. and G.N. Sullivan, 1978. Speleology, The Study Of Caves, 150 pp. A very good brief introduction to
speleology for the layperson.

Kerbo, R., 1981. Caves. Children's Press, Chicago, 48 pp. Possibly the best book on caves for very young readers. Kerbo
writes with the young audience always in mind but uses geologically correct terminology and explanations.

Halliday, Dr. W.R. , 1976. Depths Of The Earth, 432 pp. Hair-raising stories of American caving and a fair account of the
history of caving in America.

Conn, H. and J., 1977. The Jewel Cave Adventure, 240 pp. The fascinating story of two people exploring and mapping in
what is now the second longest cave in the U.S.

Jackson, D.D., 1982. Underground Worlds, 177 pp. Part of the Time-Life Planet Earth series. Many photographs and
illustrations in color.

Hassemer, J., Editor, 1982. Caving Basics, 125 pp. Chapters written by various authors (all experienced cavers). Writing
style varies considerably and some of the chapters are excellent.

Mohr, C.E. and T.L. Poulson, 1966. The Life Of The Cave, 232 pp. A popular book devoted to cave life. Many fine
photographs and illustrations. Directed to the high school level.

Palmer, A.N,, 1984. Jewel Cave, A Gift From the Past. Fenske Printing, Rapid City, 41 pp. This book provides a beautifully
illustrated and detailed discussion of the history and geology of Jewel Cave.

Palmer, A. N., 1988. Wind Cave, An Ancient World Beneath the Hills. Pixel Corp., Denver, CO., 49 pp. This book provides
a detailed and illustrated discussion of the history and geology of the Wind Cave.

Cave-related Organizations

The National Speleological Society
Cave Avenue
Huntsville, AL 35810

American Cave Conservation Association
P.O. Box 409
Horse Cave, KY 42749

Written By:
Jim Nepstad, Wind Cave National Park, Hot Springs, S.D.

Reviewed By:
Martin Ott, Superintendent, Wind Cave National Park, Hot Springs, S.D.

Publication of the Cave of South Dakota fact sheet was funded by the S.D. Department of Game, Fish, and Parks, Division of Wildlife, Pierre, SD.