Big Run: Fossil Hunting in Lycoming County, Pennsylvania

Updated June 2026

Big Run is a mapped rockhounding spot in Lycoming County, Pennsylvania. Reported finds include radioactive copper, fossils. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Lycoming County
State: Pennsylvania
Nearest road: Big Run Road
Postcode: 17737
Coordinates: 41.29834, -76.69335

Geology at Big Run

This spot sits on Catskill Formation, mapped as sandstone, siltstone, and shale that formed roughly 385 to 360 million years ago. Sedimentary layers like these are where fossils are typically preserved, and fresh exposures after rain or in active cuts tend to produce best.

Mapped unit: Catskill Formation
Age: 385–360 Ma (Late Devonian)
Rock types: sandstone, siltstone, and shale
Elevation: 760 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 Big Run

Best months: March to November. Typical highs run 84°F in midsummer and 34°F in midwinter, with winter lows near 19°F.

Climate normals: NOAA 1991-2020 monthlies, WILLIAMSPORT RGNL AP station (12 mi away), adjusted for elevation.

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 Big Run

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 Big Run.

Big Run FAQ

Where is Big Run?+

Big Run is in Lycoming County, Pennsylvania, at 41.29834, -76.69335. Nearest road: Big Run Road.

What rocks and minerals can you find at Big Run?+

Big Run is reported to produce Radioactive Copper, Fossils.

Is collecting allowed at Big Run?+

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 Big Run?+

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 Big Run?+

The most comfortable months at Big Run are March to November.

How do I get to Big Run?+

Open the directions link to navigate to 41.29834, -76.69335 in Google Maps. The nearest road is Big Run Road.

More rockhounding in Pennsylvania

See all 88 Pennsylvania spots →

Open Big Run on the map

Use the RockHoundR app for live land overlays, weather, geology, directions, and saved finds.