Cave-in-Rock State Park is an Illinois state park on 204 acres (82.6 ha) in Hardin County, Illinois

Illinois

Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...

 in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. The state park contains the historic Cave-in-Rock, a landmark of the Ohio River

Ohio River

The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...

. It is maintained by the Illinois Department of Natural Resources

Illinois Department of Natural Resources

The Illinois Department of Natural Resources is a cabinet-level department of the state government of Illinois. It is headquartered in the state capital of Springfield...

 (IDNR).

Geology

The Cave-in-Rock was worn into the limestone bluffs of the Ohio by river floods, especially during the meltoff following the Wisconsin

Wisconsin glaciation

The last glacial period was the most recent glacial period within the current ice age occurring during the last years of the Pleistocene, from approximately 110,000 to 10,000 years ago....

 ice age. It is not a karst

KARST

Kilometer-square Area Radio Synthesis Telescope is a Chinese telescope project to which FAST is a forerunner. KARST is a set of large spherical reflectors on karst landforms, which are bowlshaped limestone sinkholes named after the Kras region in Slovenia and Northern Italy. It will consist of...

land cavern like Mammoth Cave in nearby Kentucky

Kentucky

The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...

; it is an obvious, 55 feet (16.8 m) wide tunnel leading a short distance into the bluff.

History

Cave-in-Rock was known and used for thousands of years by the Native Americans. It was mapped and named in 1729 by the French explorer de Lery, who named it the caverne dans le Roc. This name, translated directly into English, is the name the cave bears to this day.

During the 1790s and first decade of the 19th century, Cave-in-Rock reached the height of its notoriety. Flatboats carrying farm produce from Kentucky, Ohio, and southern Indiana began to float down the Ohio River towards the marketplace in New Orleans. As a known Ohio River landmark, the cave was a landmark of this dangerous journey. From approximately 1797 until 1799, the cave was a hideout for a notorious gang of bandits, headed by Samuel Mason

Samuel Mason

Samuel Mason or Meason was a Revolutionary War militia captain on the frontier, who following the war, became the leader of a gang of river pirates and highwaymen on the lower Ohio River and the Mississippi River in the late 18th and early 19th centuries...

, that preyed upon the lawless river commerce.

Later in the 19th century, Cave-in-Rock was tamed by settlers who formed the river town of Cave-in-Rock, Illinois

Cave-In-Rock, Illinois

Cave-In-Rock is a village in Hardin County, Illinois, United States. Its principal feature and attraction is a large nearby cave on the banks of the Ohio River. Cave-in-Rock was originally a stronghold for outlaws including; river pirates and highwaymen, Samuel Mason and James Ford, tavern...

 near the cave. The town survives to this day. It became the site of a river ferry

Ferry

A ferry is a form of transportation, usually a boat, but sometimes a ship, used to carry primarily passengers, and sometimes vehicles and cargo as well, across a body of water. Most ferries operate on regular, frequent, return services...

, adjacent to the state park, that crosses the Ohio River from Illinois Route 1

Illinois Route 1

Illinois Route 1 is a state highway in the U.S. state of Illinois. Running parallel to the Indiana border, it is also the longest state road, starting on the south side of Chicago as Halsted Street at the intersection with 95th Street, south to a free ferry crossing to Kentucky at Cave-In-Rock on...

 to Kentucky Route 91.

State park

In 1929, the state of Illinois acquired 64.5 acres of land, including the cave. Other small parcels of land were acquired later to form the current park. The state park, which stretches from the river's edge to the top of the adjacent 60 feet (18.3 m) tall bluff, is maintained by IDNR for Ohio River access, camping, and hiking, including hikes to the historic cave.