There are 23 National Natural Landmarks in Ohio.
Name Image Date Location County Ownership Description Arthur B. Williams Memorial Woods Cuyahoga municipal A remarkably pristine remnant beech-maple forest Blacklick Woods Fairfield county An outstanding example of relatively undisturbed, old-growth beech-maple and swamp forest communities Brown's Lake Bog Wayne private One of the few well-preserved, virgin boreal acid bogs remaining in a region where wetlands have been drained for agricultural use. Buzzardroost Rock, Lynx Prairie, The Wilderness Adams private Supports many rare or uncommon species and it has an almost 50- year history of scientific observations. Cedar Bog Champaign state An excellent example of a marl swamp. Part of Cedar Bog State Nature Preserve. Clear Fork Gorge Ashland state Clearly illustrates evidence of stream reversal due to the Wisconsin glacier. Located in Mohican State Park. Clifton Gorge Greene state Exemplary of interglacial and postglacial canyon-cutting into the dolomites of the Niagara Escarpment. Part of Clifton Gorge State Nature Preserve. Crall Woods Ashland private A near-virgin remnant of maple-basswood-beech forest-type. Cranberry Bog Licking state The only known bog of its type in existence. Part of Cranberry Bog State Nature Preserve. Dysart Woods Belmont state One of the finest remaining examples of the white oak forests of eastern Ohio. Managed by Ohio University. Fort Hill State Memorial Hillsboro Highland state Excellent outcrops of Silurian, Devonian, and Mississippian sedimentary bedrock and a natural bridge. Glacial Grooves State Memorial Erie state Very large limestone glacial grooves. Glen Helen Natural Area Greene private Includes a waterfall that carved a large travertine bowl around its pool. Goll Woods Fulton state One of the best remaining examples of an oak-hickory dominated forest in Ohio. Part of Goll Woods State Nature Preserve. Hazelwood Botanical Preserve Hamilton state Highly detailed study of the site's plant ecology was published in 1929. Managed by the University of Cincinnati. Highbanks Natural Area Delaware, Franklin county A forested bluff overlooking the Olentangy River. Holden Natural Area Geauga, Lake private A complex of three natural areas. Hueston Woods Butler, Preble state A noteworthy example of beech-maple climax forest that has never been cut. Located in Hueston Woods State Park. Mantua Swamp Portage private Contains many different wetland communities. Mentor Marsh Lake state Consists of marsh vegetation, aquatic plants, swamp and bottomland forest, and upland forest. Part of Mentor Marsh State Nature Preserve. Serpent Mound Cryptoexplosive Structure Adams, Highland, Pike private A structure of undetermined origin exposed by differential erosion. Tinker's Creek Gorge Cuyahoga municipal Contains a virgin oak-hickory and virgin beech-maple-hemlock forest. White Pine Bog Forest Geauga municipal, private The only remaining near-virgin remnant white pine boreal bog in Ohio.
See also
List of National Historic Landmarks in Ohio