Union Bridge: Pink Marble & Green Marble Rockhounding in Carroll County, Maryland

Updated June 2026

Union Bridge is a mapped rockhounding spot in Carroll County, Maryland. Reported finds include pink marble, green marble. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Carroll County
State: Maryland
Nearest road: Quaker Hill Road
Postcode: 21791
Coordinates: 39.55408, -77.17261

Geology at Union Bridge

This spot sits on Sams Creek Metabasalt, mapped as metabasalt that formed roughly 2500 to 540 million years ago. Volcanic ground like this weathers into rocky slopes and float, and fresh exposures in cuts and drainages are usually the most productive places to look.

Mapped unit: Sams Creek Metabasalt
Age: 2500–540 Ma (Proterozoic)
Rock types: metabasalt
Elevation: 340 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 Union Bridge

Best months: March to November. Typical highs run 86°F in midsummer and 40°F in midwinter, with winter lows near 23°F.

Climate normals: NOAA 1991-2020 monthlies, EMMITSBURG 2 SE station (10 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 Union Bridge

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 Union Bridge.

Across the state line from Union Bridge

Union Bridge is close enough to the Maryland border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

Union Bridge FAQ

Where is Union Bridge?+

Union Bridge is in Carroll County, Maryland, at 39.55408, -77.17261. Nearest road: Quaker Hill Road.

What rocks and minerals can you find at Union Bridge?+

Union Bridge is reported to produce Pink Marble, Green Marble.

Is collecting allowed at Union Bridge?+

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 Union Bridge?+

A rock hammer, sturdy gloves, safety glasses, and a collecting bag cover the basics here. Add a spray bottle: wet rock shows color and pattern that dry rock hides.

When is the best time to visit Union Bridge?+

The most comfortable months at Union Bridge are March to November.

How do I get to Union Bridge?+

Open the directions link to navigate to 39.55408, -77.17261 in Google Maps. The nearest road is Quaker Hill Road.

More rockhounding in Maryland

See all 42 Maryland spots →

Open Union Bridge on the map

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