Photograph inside of Mammoth Cave in Kentucky.

Kentucky Earth Science Quick Facts

Page snapshot: Kentucky State Geologic MapFossil; Rock; Mineral; GemHighest and Lowest Elevations; Places to Visit; and Additional Resources.

Image above: Little Bat Avenue inside of Mammoth Cave National Park, Kentucky. Photograph by Don Sniegowski (Flickr; Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Generic license); image cropped and resized).

Geologic Map of Kentucky


Geologic map of Kentucky with physiographic regions identified.

Geologic map of Kentucky showing maximum ages of mappable units. Image by Jonathan R. Hendricks for the [email protected] project developed using QGIS and USGS data (public domain) from Fenneman and Johnson (1946) and Horton et al. (2017).

Kentucky State Fossil: Brachiopod

Kentucky's state fossil is a brachiopod (genus and species not stated). Brachiopod fossils are especially common in Ordovician-aged rocks in Kentucky near Cincinnati, Ohio. Learn more about brachiopods on the Digital Encyclopedia of Ancient Life.


Photograph of a sample of Ordovician rock from Kentucky that is covered in fossil brachiopod shells.

Brachiopods from the Ordovician of Kentucky. Photograph by Kyle Hartshorn (Flickr; Creative Commons Attribution 2.0 Generic license; image cropped and resized).

Kentucky State Rock: Kentucky Agate

Agate is a fine-grained and layered form of quartz, often having bright colors exhibited in patterns and bands. Kentucky agates are Mississippian in age and come in a variety of beautiful colors including red, black, gray, and yellow.


Photograph of a sample of Kentucky agate.

Sample of cut and polished agate from Kentucky (Mississippian Borden Formation). Photograph by James St. John (Flicker; Creative Commons Attribution 2.0 Generic license; image resized).

Kentucky State Mineral: Coal

Although the coal is not technically a mineral, it is legally considered a mineral resource thanks to its use as a fossil fuel. Kentucky is one of the top producers of coal in the US, mining 150–160 million tons annually.


Photograph of a sample of coal from Kentucky.

Sample of bituminous coal from the Pennsylvanian of Kentucky. Photograph by James St. John (Flicker; Creative Commons Attribution 2.0 Generic license; image resized).

Kentucky State Gem: Freshwater Pearl

While most gemstones are minerals, pearls are formed when an irritant (usually a sand grain) makes its way inside the body of a bivalve mollusk such as a mussel. The animal secretes a lining of calcium carbonate called nacre around the irritant to protect itself, forming a pearl. Due to overharvesting, pollution, and habitat loss, Kentucky’s natural pearl-producing mussels are at risk.


Photograph of shells of the fluted kidneyshell mussel.

Shells of the fluted kidneyshell (Ptychobranchus subtentum), a type of freshwater mussel known from Kentucky and other nearby states. Photograph by the U.S. Fish and Wildlife Service (Flickr; Creative Commons Attribution 2.0 Generic license).

Kentucky's Highest and Lowest Elevations

Highest Elevation: Black Mountain

At 1263 meters (4139 feet) above sea level, Black Mountain is Kentucky's highest point, located in the Appalachians near the Virginia border in Harlan County. The mountain is located near rich coal veins and was threatened by mountaintop removal mining until the state purchased rights to the summit in 1999.


Photograph of Black Mountain, the highest point in Kentucky.

Black Mountain, Kentucky, the highest point in the state. Photograph by "iLoveMountains.org" (Flickr; Creative Commons Attribution 2.0 Generic license).


Lowest Elevation: Mississippi River at Kentucky Bend

The Mississippi River at Kentucky Bend in southwestern Kentucky is the lowest point in the state, with an elevation of 78 meters (257 feet).

Photograph of Kentucky Bend on the Mississippi River, the lowest point in Kentucky.

Kentucky Bend, the lowest point in Kentucky, as viewed from across the Mississippi River in New Madrid, Missouri. Photograph by Jimmy Emerson (Flickr; Creative Commons Attribution-NonCommercial-NoDerivs 2.0 Generic license).

Places to Visit


Mammoth Cave

Mammoth Cave, Kentucky. Learn more about the rocks of Mammoth Cave here.


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Photograph inside of Mammoth Cave in Kentucky.

Stalagmites forming in Onyx Cave, Mammoth Cave National Park, Kentucky. Photograph by "Navin75" (Flickr; Creative Commons Attribution-ShareAlike 2.0 Generic license).


Cumberland Falls

Corbin, Kentucky. Learn more about the topography of  Cumberland Falls here.


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Photograph of Cumberland Falls waterfall in Kentucky.

Cumberland Falls in southeastern Kentucky. Photograph by Jim Bauer (Flickr; Creative Commons Attribution-NoDerivs 2.0 Generic license).


Red River Gorge Geological Area, Daniel Boone National Forest

Stanton, Kentucky.


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Photograph of rocks at Red River Gorge in Kentucky.

The Auxier Ridge Trail at Red River Gorge Geological Area in Kentucky. Photograph by "The Cut" (Flickr; Creative Commons Attribution 2.0 Generic license; image resized).

Additional resources


Learn more about the Earth science of Kentucky and the surrounding region on [email protected]


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Simple map of the southeastern United States showing the boundaries of the Inland Basin, Coastal Plain, and Blue Ridge and Piedmont regions.

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