Appendix A: National Natural Landmarks

The National Natural Landmark (NNL) program was established by the secretary of the interior in 1962 under the authority of the Historic Sites Act of 1935. The purpose of establishing the program was to identify and encourage the preservation of the full range of geological and ecological features that represent nationally significant examples of the nation’s natural heritage. National natural landmarks can be on either public or private land. Landowners must indicate consent for designation of a national natural landmark on their property. Designation of a national natural landmark is not a federal land withdrawal, it does not change ownership, it does not dictate federal activity, and it does not guarantee public access. It is the designation of a significant feature of the nation’s natural heritage (see the National Natural Landmarks/ National Historic Landmarks map).





Horseshoe Lake Natural Preserve

Alexander County, Illinois


Natural preserve contains diverse acquatic and terrestrial flora and fauna and mature stands of bald cypress. The site is on the migration corridor of many waterfowl as well as being an overwintering area for thousands of Canada geese.

Little Grand Canyon Area

Jackson County, Illinois


An exceptional example of a large box canyon with vertical overhanging walls and contains a great diversity of ecosystems, including sandstone outcrops and overhangs, ravine slope forest, dry site oak- hickory forest, and hill prairies. The ravine is nationally known as a seasonal haven for a great variety of snakes that hibernate there.

Fults Hills Prairie Nature Preserve

Monroe County, Illinois


This nature preserve contains the largest complex of high- quality undisturbed loess hill prairies along the Mississippi River in Illinois, including the largest single prairie opening.

Giant City Geologic Area (In Gicant City State Park)

Union County, Illinois


This area is an exceptional example of gravity sliding, consisting of massive joint- bounded sandstone blocks of Pennsylvania Age. Rich flora include zeric woods and oak/ hickory forest.

Henderson Sloughs

Uniontown, Kentucky


One of the largest wetlands remaining in Kentucky. It is an important habitat for waterfowl and other wildlife. It was also the home of John James Audobon.

Mark Twain and Cameron Caves

Marion County, Missouri


Two caves on either side of a small valley, Cave Hollow, are exceptionally good examples of the maze type of cavern development.

Big Oak Tree (In Big Oak Tree State Park)

Southeast of East Prairie, Missouri


This area is the only sizable tract of essentially virgin wet-mesic bottomland habitat.

Pickle Springs

St. Genevieve County, Missouri

State and Private

A deep, forested gorge containing one of the finest Pleistocene relict habitats in Missouri. It supports many relict herbaceous plant species, including one rare moss of tropical affinity and several plant species characteristic of the Appalachian Mountains.

Reelfoot Lake

Lake County, Tennessee


Contains water lily glades, cypress swamps, sawgrass jungles, and scattered bodies of open water formed in the winter of 1811- 12 as a result of the New Madrid earthquake. The site contains domes, sunken lands, fissures, sinks, sand blows, and extensive landslides.

Big Lake Natural Area

Mississippi County, Arkansas


This natural area contains a significant amount of virgin timber and a mix of southern, mid-western, and Ozark flora, and supports several endangered bird species.

Green Ash Overcup Oak Sweetgum Research Natural Area (In Delta National Forest)

Sharkey County, Mississippi


The area contains three very rare remnants of virgin bottomland hardwood forest in the Mississippi River Delta Region. Some of the oldest sweetgum stands are 250- 300 years old.

Mississippi Petrified Forest

Flora, Mississippi


This area contains petrified remains of sequoia, maple, fir, birch, spurge and other trees deposited millions of years ago by as the result of a catastrophic event and eventually uncovered through processes of erosion.

Last updated: November 16, 2017