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Hueston Woods State Park: Fossil Hunting in Preble County, Ohio

Updated July 2026

Hueston Woods is one of the few Ohio state parks that permits fossil collecting, and it is regarded as one of the best places in the world to find Upper Ordovician fossils. Stream cuts and shoreline exposures around Acton Lake produce brachiopods, bryozoans, crinoids, and trilobites weathered from the Cincinnatian bedrock. The most productive spots are the Four Mile Creek picnic area near the dam, the Covered Bridge area, and the stream cuts at the north end of the lake. Reported finds include fossils, trilobites, brachiopods, bryozoans, crinoids. Below: coordinates, access notes, nearby spots, and trip-planning links.

Hueston Woods State Park photos

Public image records connected to this spot or its reported material.

1 photo

Acton Lake at Hueston Woods State Park, where Ordovician fossils weather from the shoreline and creek beds, Preble County, Ohio

Quick details

Access: Public area
County: Preble County
State: Ohio
Nearest road: Four Mile Creek
Postcode: 45003
Coordinates: 39.58097, -84.74896

Geology at Hueston Woods State Park

This spot sits on Drakes, Whitewater and Liberty Formations, Undivided, mapped as shale and limestone that formed roughly 455 to 445 million years ago. Limestone like this typically forms in ancient seas, so marine fossils such as brachiopods, corals, and crinoids tend to weather out of fresh exposures.

Mapped unit: Drakes, Whitewater and Liberty Formations, Undivided
Age: 455–445 Ma (Late Ordovician)
Rock types: shale and limestone
Elevation: 940 ft

Geologic mapping via Macrostrat and the underlying state geological survey maps (CC BY 4.0). Bedrock at the surface can vary within a mapped unit.

Best time to visit Hueston Woods State Park

Best months: March to November. Typical highs run 85°F in midsummer and 36°F in midwinter, with winter lows near 18°F.

Climate normals: NOAA 1991-2020 monthlies, EATON station (12 mi away).

Land & collecting status

Generally open to casual rockhounding

Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig.

Public-land rules vary by agency, season, and field office. The RockHoundR app pulls live BLM, USFS, NPS, and tribal overlays so you can see exactly which agency manages the ground at this spot.

Sources & verification

Spot details combine the public RockHoundR location dataset, normalized mineral labels, agency land-status checks in the app, and community submissions. Coordinates are approximate until verified in the field.

Sources: RockHoundR public spot dataset, app land overlays, and local agency review before each trip.

Found at Hueston Woods State Park

Each chip opens all spots that produce that material; the encyclopedia link opens the full ID and field guide.

Nearby rockhounding spots

Other rockhounding spots within driving distance of Hueston Woods State Park.

Across the state line from Hueston Woods State Park

Hueston Woods State Park is close enough to the Ohio border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

Hueston Woods State Park FAQ

Where is Hueston Woods State Park?+

Hueston Woods State Park is in Preble County, Ohio, at 39.58097, -84.74896. Nearest road: Four Mile Creek.

What rocks and minerals can you find at Hueston Woods State Park?+

Hueston Woods State Park is reported to produce Fossils, Trilobites, Brachiopods, Bryozoans, Crinoids.

Is collecting allowed at Hueston Woods State Park?+

Generally open to casual rockhounding. Most public-tagged spots sit on BLM, U.S. Forest Service, or other federal land where reasonable hand collecting of common rocks and minerals is allowed. Confirm posted rules and active mining claims before you dig. Always confirm current rules with the managing agency before a trip.

What tools should I bring to Hueston Woods State Park?+

A rock hammer, a cold chisel, safety glasses, and newspaper or foam for wrapping finds cover most fossil ground. A trowel and a sieve help in soft exposures.

When is the best time to visit Hueston Woods State Park?+

The most comfortable months at Hueston Woods State Park are March to November.

How do I get to Hueston Woods State Park?+

Open the directions link to navigate to 39.58097, -84.74896 in Google Maps. The nearest road is Four Mile Creek.

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