On my way there I had 2 mornings of glorious sunrises to greet me on my drive from Washington State to Wyoming.

Managed by the National Park Service, Fossil Butte National Monument, was established on October 23 1972 and is located in southwest Wyoming. This monument holds one of the largest deposits of freshwater fish fossils in the world from the Eocene Epoch, 34 to 56 million years ago. In prehistoric times, this part of Wyoming was a sub-tropical lake ecosystem with calm waters, lack of scavengers and a fine sediment that all worked together to create conditions perfect for preserving fossils from the Cenozoic aquatic communities of North America.

For over the two million years Fossil Lake covered an area of 40 to 50 miles (64 to 80 k) long north to south and 20 miles (32 k) wide of southwest Wyoming. Today less than 1.5% of Fossil Lake is protected and managed by the National Park Service. Fossil Butte National Monument promotes the protection of this world-class archeological heritage. The Monument contains only 8,198 acres (33,180,000 m²) of the 595,200 acres (2.409×10⁹ m²) of ancient lakebed. The Green River Formation’s ancient subtropical freshwater lake bed preserved 27 species of fish, 2 bat species,10 mammal species,15 species of reptiles that include turtles, lizards, crocodilians, and snakes, 2 extremely rare amphibian species have been identified, insects including spiders, dragonflies and damselflies, crickets’ stoneflies, true bugs, beetles, wasps, bees, ants, moths, butterflies and flies and plants. As major indicators of climate, plants are allowing scientists to study the ancient ecology of the Fossil Lake area. 

When fossils were discovered, coal miners in the area dug them up and sold them to collectors. Commercial and private fossil collecting is not allowed within the National Monument, although private quarries nearby continue to produce fossil specimens, both for museums and for private collectors.

There are over 80 fossils and casts on display in the Monument’s Visitor Center and a 13-minute video showing how fossils are found and what has been learned along with interactive exhibits. During the summer, lab personnel prepare fossils in public. Summer activities also include ranger programs, hikes, paleontology and geology talks, and participation in fossil quarry collections for the park. 

The base of Fossil Butte is defined by the bright red, purple, yellow and gray beds of the Wasatch Formation. Eroded portions of these horizontal beds slope gradually upward from the valley floor and steepen abruptly. Overlying them and extending to the top of the butte are the much steeper buff-to-white beds of the Green River Formation, which are about 300 feet thick. 

Quarry programs take place Fridays and Saturdays mid-June through late August between 11 a.m. and 3 p.m. If you wish to learn about the research and help search for fossils, meet at the Nature Trail and hike a half mile (0.8 k) to the quarry. All fossils found during the program are collected and contributed to the site’s scientific research.

There are several maintained hiking trails less than 3-miles (4.8k) long and two-track dirt roads (closed to vehicles) that spur off Scenic Drive. Scenic Drive is paved until the Nature Trail then it becomes a dirt/gravel road continuing to the north boundary of the Monument. All hikes allow visitors to take in the site’s unique landscape and geological features. Remember if fossils are discovered do not disturb them and inform a ranger as to the location, so that a qualified team can investigate and determine how to handle the fossil.