Sunday | April 12, 2026
Yellowcat: Agates to Uranium
Led by geologist David Berry
Only a 45-minute drive from Green River, the Yellowcat district is a historic uranium mining area, also well-known by geologists and paleontologists. Along the way, we will stop at an overlook with stunning views of the subvolcanic La Sal Mountains, the Book Cliffs, and the Uncompahgre Plateau. At this stop we will discuss deep geologic time and David will present a brief geologic history of the region, from the Great Unconformity upon the 1.7 billion year old Black Rocks to the extensive Eocene lakes that deposited the Green River Formation.
At Yellowcat, we will look at ruins of uranium mining, and David will talk about the geology of local uranium deposits, as well as offer a historical perspective of uranium production in the Colorado Plateau. Finally, we will rockhound for agates, barite balls, and maybe even see a few dino bone chips (these must be left in place).
This is a full-day driving trip through the Yellowcat area east of Green River that includes hiking up steep slopes.
This trip is not recommended for young children due to potential hazards at mine sites.
See below for more trip information.
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Participants must drive their own vehicles.
High-clearance vehicles with are required. Anticipate short sections of rough road.
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A full tank of gas.
Lunch, water, snacks, camera, binoculars. A Geiger counter if you have one!
Sturdy shoes - we will be walking off-trail ½ mile or more on stops.
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David Berry
GeologistDavid Berry is a retired geologist and water manager. As a geologist, he was primarily involved with minerals exploration and environmental work. More recently, he taught geology classes as a lecturer at Colorado Mesa University.
