John Day River at Cottonwood Canyon State Park: Agate & Jasper Rockhounding in Gilliam County, Oregon

Updated August 2026

John Day River at Cottonwood Canyon State Park is a mapped rockhounding spot in Gilliam County, Oregon. Reported finds include agate, jasper, petrified wood. Below: coordinates, access notes, nearby spots, and trip-planning links.

Quick details

Access: Public area
County: Gilliam County
State: Oregon
Coordinates: 45.46987, -120.42929

Geology at John Day River at Cottonwood Canyon State Park

This spot sits on Columbia River Basalt Group; Grande Ronde Basalt; Normal magnetostratigraphic unit 2, mapped as basalt flows that formed roughly 23 to 5 million years ago. Petrified wood typically comes from volcanic ash beds like the ones associated with this ground, where buried forests were slowly replaced by silica.

Mapped unit: Columbia River Basalt Group; Grande Ronde Basalt; Normal magnetostratigraphic unit 2
Age: 23–5 Ma (Miocene)
Rock types: basalt flows
Elevation: 520 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 John Day River at Cottonwood Canyon State Park

Best months: January to November. Typical highs run 89°F in midsummer and 45°F in midwinter, with winter lows near 29°F.

Climate normals: NOAA 1991-2020 monthlies, MORO station (14 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.

State guidance last verified: April 1, 2026

BLM Oregon/Washington — Rockhounding & mineral material
Oregon Department of Geology and Mineral Industries (DOGAMI)
Oregon Parks and Recreation Department — beach collecting rules
Community submissions reviewed against published agency rules

Found at John Day River at Cottonwood Canyon 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 John Day River at Cottonwood Canyon State Park.

Across the state line from John Day River at Cottonwood Canyon State Park

John Day River at Cottonwood Canyon State Park is close enough to the Oregon border that the next-closest rockhounding spots are in a neighboring state. Worth knowing if you are already on the road.

John Day River at Cottonwood Canyon State Park FAQ

Where is John Day River at Cottonwood Canyon State Park?+

John Day River at Cottonwood Canyon State Park is in Gilliam County, Oregon, at 45.46987, -120.42929.

What rocks and minerals can you find at John Day River at Cottonwood Canyon State Park?+

John Day River at Cottonwood Canyon State Park is reported to produce Agate, Jasper, Petrified Wood.

Is collecting allowed at John Day River at Cottonwood Canyon 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 John Day River at Cottonwood Canyon State Park?+

A rock hammer, sturdy gloves, and a padded bag cover petrified wood hunting. Most pieces are surface float, so walking slopes and washes beats digging.

When is the best time to visit John Day River at Cottonwood Canyon State Park?+

The most comfortable months at John Day River at Cottonwood Canyon State Park are January to November.

How do I get to John Day River at Cottonwood Canyon State Park?+

Open the directions link to navigate to 45.46987, -120.42929 in Google Maps. Some spots are remote, so check road conditions before driving out.

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