Exploring the Nation’s Trailside Geoheritage Sites
From small outcrops to canyons carved into vast land tracts, the earth’s geology has always been an invitation— pulling people into nature. Since 2021, the U.S. Geological Survey’s (USGS’) Geoheritage Sites of the Nation project has identified geological sites that have “played a significant role in impacting society throughout history”—helping to shape our relationship to the landscape. Eight of these sites can be viewed and found along multiuse trails, making for awe-inspiring journeys.
Special acknowledgement to TrailLink and the USGS for the data used to create this story, with geological facts provided by the USGS National Cooperative Geologic Mapping Program and the National Park Service (NPS).
This article was originally published in the Spring/Summer 2026 issue of Rails to Trails magazine and has been reposted here in an edited format. Subscribe to read more articles about remarkable trails while also supporting our work.
District of Columbia’s Pulpit Rock: Beach Drive (Rock Creek Park)
The 5-mile Beach Drive trail wends through Washington, D.C.’s Rock Creek Park, where you can find some of the most accessible geology in the capital, according to the USGS. The area has a presidential claim to fame, with Pulpit Rock on the southern section of trail (38.945110, -77.046644) being a favorite hiking spot of Teddy Roosevelt during his presidency. Overlooking Rock Creek, Pulpit Rock hails from likely the Cambrian Period, 541–485.4 million years ago.
Access: From the trailhead at Blagden Avenue and Beach Drive, take the Theodore Roosevelt Side Trail; note that the hiking-only route can be steep and uneven, with narrow sections. Expected time is 15–20 minutes to Pulpit Rock. From here, you can turn around or continue south on the Valley Trail, which allows you to loop back onto Beach Drive in about a half mile (near Boulder Bridge).
“Geology touches every aspect of our lives. Through our shared geological heritage, we are able tell the unique stories of the incredible geology across our nation, not only from a scientific perspective, but through a human perspective.”
—Christina DeVera, Physical Scientist for the USGS and lead for the Geoheritage Sites of the Nation project
Delaware’s Wissahickon Formation of the Delaware Piedmont: Brandywine Trail
Identifiable as “steep slopes and sharp valleys,” according to the USGS, the Wissahickon Formation of the Delaware Piedmont—along the Brandywine River in Wilmington—is a set of metamorphic rock making up a portion of the Appalachian Mountains. NPS writes that the landscape was forged by “tectonic activity that occurred during the Paleozoic Era,” 541–245 million years ago. In the early 1800s, Eleuthère lrénée du Pont chose the site to produce explosive black powder, using local rock for mill buildings designed to vent accidental explosions (source: American Society of Mechanical Engineers).
You can glimpse the formation along the 2.9-mile Brandywine Trail—which travels through Brandywine Creek State Park and connects to First State National Historical Park. Look on the trail north of state Route 92/Thompsons Bridge Road and south of Ramsey Road (39.823660, -75.572111).
Access: A convenient access point with parking and restrooms is the trailhead at 4017 Thompson Bridge Road (Route 92); head north to view the formation.
Maine’s Cadillac Mountain: Carriage Roads
The glaciated landscape of Maine is a featured highlight of Acadia National Park, where Cadillac Mountain sits as the highest point on the eastern seaboard, elevation 1,530 feet. Home to the Wabanaki, or “People of the Dawn,” the summit has a radiant claim to fame as the first place to see the sunrise in the United States (Oct. 7–March 6). Crisscrossing the park to the west are the Carriage Roads—45 miles of crushed-stone pathways created a century ago by billionaire John D. Rockefeller. Containing their own scenic qualities, such as stone arch bridges, waterfalls and granite-stone guardrails nicknamed “Rockefeller’s Teeth,” the Carriage Roads also connect to multiple hiking trails to the summit.
Access: Before going, please refer to the Acadia National Park website for road and trail closures, trail usage rules and regulations, and other planning information that can change seasonally. Vehicle reservations are required to drive Cadillac Summit Road from mid-May to mid-October.
Maryland’s Mather Gorge: C&O Canal Towpath/Billy Goat Trail
The eroded cliffsides of Mather Gorge create an ethereal visual at Great Falls National Park— comprising a landscape on the Potomac River cut over an estimated 30,000 years, according to NPS. The gorge, made up of “Neoproterozoic-Cambrian metasedimentary rocks”—1 billion to 541 million years ago—is named after the first director of the NPS, Stephen Mather. You can enjoy expansive views of the gorge along the Billy Goat Trail A, a 1.7-mile hiking path that connects in Potomac, Maryland, to the 184.2-mile C&O Canal Towpath, a portion of the 3,700-mile Great American Rail-Trail®.
Access: A trailhead on the C&O Canal Towpath with parking, restrooms and water is located in Potomac at 10300 MacArthur Blvd., where a small side path (note: has steps) leads you down to the trail. Turn right (east) on the towpath to reach the Billy Goat Trail in about 0.4 mile. The Great Falls Tavern Visitor Center at 11710 MacArthur Blvd. is 0.7 mile north of the Billy Goat Trail’s northern endpoint. Please refer to NPS and the C&O Canal Trust for trail closures and details. Note: The C&O Canal Trust describes the Billy Goat Trail as demanding but rewarding.
Powell’s Great Unconformity
In Arizona’s Mojave Desert, Pima Point on the western section of the Grand Canyon Greenway features views of the Great Unconformity at the Grand Canyon, an “erosional contact representing up to 1.3 billion years of missing earth history,” writes the USGS. It is known as John Wesley Powell’s unconformity to honor the second director of the Geological Survey’s pioneering work in the region.
Massachusetts’ Race Point Beach (Cape Cod): Province Lands Bike Trail
The 7.6-mile Province Lands Bike Trail, constructed in 1967, has the distinction of being the first bike trail built by NPS. Located in the northern tip of Cape Cod, the trail forms a loop around Provincetown’s Beech Forest while connecting to multiple destinations, including Race Point Beach, a Holocene-age dune, 11,700 years ago to the present. According to NPS, the Massachusetts Humane Society started the world’s first organized lifesaving service in 1785, and outposts began to pop up on Cape Cod in the early 1800s. The federally funded Old Harbor station at Race Point Beach, built in 1897 and originally located at Nauset Beach, now houses a museum dedicated to lifesaving and maritime rescue history.
Access: Multiple trailheads with restrooms, parking and/ or water dot the Province Lands Bike Trail, including at Race Point Beach at the trail’s northern endpoint (north of the municipal airport) and the Province Lands Visitor Center on Race Point Road.
Nebraska’s Scotts Bluff: Monument Valley Pathway
Just a few miles away from the largest city in Nebraska’s panhandle, you’ll find an otherworldly site in the form of Scotts Bluff National Monument, a towering mesa of sandstone and clay rising 800 feet above the North Platte River. Scotts Bluff served as a landmark for Native Americans for thousands of years, and for people traveling west in the 1800s; today the site offers a variety of experiences for tourists, including scenic driving and hiking, historical exhibits, and displays of works by western artist William Henry Jackson. Scotts Bluff is accessible via the aptly named Monument Valley Pathway, whose southeast endpoint provides unobstructed views of the landmark.
Fun fact: Jackson’s photo documentation of the Yellowstone region—taken during an 1871 USGS expedition—helped inspire the establishment of the nation’s first national park.
Access: Multiple parking lots and other facilities can be found along the Monument Valley Pathway. From its northeast endpoint at Scottsbluff, the trail winds 6.3 miles through Terrytown and then Gering, reaching Scotts Bluff monument and the visitors center at trail’s end.
South Carolina’s Weston Lake: Congaree Boardwalk Loop
“Astonishing biodiversity exists in Richland, South Carolina’s Congaree National Park, the largest intact expanse of old growth bottomland hardwood forest remaining in the southeastern United States,” writes NPS. A feature of the park is Weston Lake, which—according to research cited by the USGS—is the “largest standing body of water on the floodplain.” You can reach an overlook via the 2.4-mile Congaree Boardwalk Loop, which forms a square leading south to the lake from its trailhead near the Harry Hampton Visitor Center. The trail also features a variety of wildlife, from deer and otters to alligators, as well as views of Cedar Creek.
Access: Sections of the boardwalk will be closed for scheduled improvements on a rolling basis, with detours provided. Access the boardwalk and Weston Lake from the visitor center on National Park Road.
Note: This article was updated on June 8, 2026.
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