Rock Butte – April 2025
We were driving up Arizona State Route 89 and looking for anything interesting on our drive. Small crinoid fossils at Rock Butte are mentioned in all of the Arizona guidebooks that we use. The photos in all the books did not look too promising, so our hopes were not set too high.
The location is only 3 miles off State Route 89, but the road is rough and would not be drivable for cars without good ground clearance. The fossils are located in limestone that was at one point quarried. There is a large brick kiln in front of the quarry, but it’s fenced off because the kiln is in a state of disrepair and not safe to go near. There were signs designating the kiln as a protected under the Antiquities Act of 1906 as a culturally significant item, but the sign didn’t explain anything about the history of the kiln: when it was used, what it was used for and who built it.
The fossils are located in the quarry behind the kiln, but the rocks around the quarry had more fossils in them than the rocks in the quarry pit. The main pit was mostly light gray rocks, which were not as desirable. We had more luck with the brown-gray rocks.
The fossils were very numerous but also very small. We haven’t done much crinoid collecting so this stop was worth it, but for the more experienced collector this might not be a place to go out of your way to go to. We are not fossil experts so we aren’t too knowledgeable about what fossils we were looking at, but according to geologic maps the rock is Redwall Limestone and approximately 337-353 million years old.
The parking area is located at: 34.98691, -112.45406