Fossil Butte National Monument–What is it Known For?

Picture of Fossil Butte

By Richelle Primm, SVI Media

Make sure to add visiting the Fossil Butte National Monument to your summer activities.

Whether you want to hike, visit the aquarium in stone (the only one in the world, by the way), or find a fossil yourself, this would be a fun event for the whole family.

Fossil Butte is located about 80 miles south of here, between Afton and Kemmerer.

“The abundance, diversity, and quality of preservation is what makes the Green River Formation fossils so unique. Here at Fossil Butte, we display over 300 of them in our visitor center,” Kim Acker, Supervisory Park Ranger for Fossil Butte National Monument, said.

Acker said most of the main fossil interest started in the 1860s when the building of the first transcontinental railroad began.

“As some workers were blasting rock for a section of rail near what is now Green River, WY, they noticed fossils in the cut. Commercial quarriers and researchers alike took an interest in digging further,” Acker said. “A century later, we now understand that this area was once a warm, temperate environment.”

Acker continued, “There was a large freshwater lake that was home to crocodilians, turtles, fish, and more.” … “Fossil Butte itself, along with other high buttes remaining in the area, were once the bottom of the lake, where fish and other animals sank after death to become fossilized.”

Due to a combination of a densely vegetated terrestrial ecosystem, an abundance of life in the lake and the surrounding ecosystem, and a lack of predators, this led to an abundance and diversity of excellently preserved fossils, Acker said.

She said, “To date, we have found over 400 different species, ranging from plants, to aquatic animals, to terrestrial reptiles and mammals.”

The Fossil Butte staff provide various activities for those visiting to help the history and fossils come to life.

Acker said there are two established hiking trails along with 8 thousand acres of open back-country. You can hike to the top of Nature Trail and watch a Geoscientist excavate and catalog fossils. On your exploration, you have the chance of seeing wildlife such as moose, pronghorn, elk, and birds.

There are also fossil preparation demonstrations to see how fossils go from the ground to display, and rangers discuss topics from earth and cultural history, to geology, to modern day plants and animals. For those who visit on Friday or Saturday, the research quarry is open to the public. Also, if you’re interested in exploring Fossil Butte after dark, it has an exceptional night sky.

“My favorite part about my job is seeing visitors (young and old) look at the fossils and just say “wow,”” Acker said. “They can’t believe that Wyoming was so different 52 million years ago, or that something could be preserved so perfectly for that long.”

If you’re interested in learning more about Fossil Butte, you can call the office at 307-800-8404 or visit the website at The park is located at 864 Chicken Creek Rd., Kemmerer, WY, 83101.

“By sharing the Fossil Butte story, we hope more people will come and see us in person,” Acker said.

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