Erdman Farm: Fossil Hunting in Karnes County, Texas

Updated June 2026

Erdman Farm is a mapped rockhounding spot in Karnes County, Texas. Reported finds include petrified palm wood, opalized wood, fossils. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Karnes County
State: Texas
Nearest road: FM 887
Postcode: 78113
Coordinates: 29.00051, -98.01955

Geology at Erdman Farm

This spot sits on ground mapped as Alluvium, undivided that formed within roughly the last 3 million years. Reworked sediments like these can carry fossils eroded from older beds upstream, typically as rolled bone fragments, teeth, and shell material.

Mapped unit: Alluvium, undivided
Age: 3 Ma to present (Pleistocene to Holocene)
Elevation: 350 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 Erdman Farm

Best months: October to May. Typical highs run 96°F in midsummer and 65°F in midwinter, with winter lows near 43°F. Summer heat here is intense, so carry more water than you think you need and work the early morning.

Climate normals: NOAA 1991-2020 monthlies, KARNES CITY 2N station (11 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.

State guidance last verified: April 1, 2026

Texas Parks and Wildlife Department
Bureau of Economic Geology — Texas geology
Big Bend National Park — Rules
Community submissions reviewed against published agency rules

Found at Erdman Farm

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 Erdman Farm.

Erdman Farm FAQ

Where is Erdman Farm?+

Erdman Farm is in Karnes County, Texas, at 29.00051, -98.01955. Nearest road: FM 887.

What rocks and minerals can you find at Erdman Farm?+

Erdman Farm is reported to produce Petrified Palm Wood, Opalized Wood, Fossils.

Is collecting allowed at Erdman Farm?+

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 Erdman Farm?+

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 Erdman Farm?+

The most comfortable months at Erdman Farm are October to May. Summer heat here is intense, so carry more water than you think you need and work the early morning.

How do I get to Erdman Farm?+

Open the directions link to navigate to 29.00051, -98.01955 in Google Maps. The nearest road is FM 887.

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Open Erdman Farm on the map

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