The 50 million year old lake bed protected by Fossil Butte National Monument is one of the richest fossil localities in the world. Recorded in limestone are dynamic and complete paleoecosystems that spanned two million years. Preservation is so complete that it allows for detailed study of climate change and its effects on biological communities. Visitors discover that this resource displays the interrelationships of plants, insects, fishes, reptiles and mammals, like few other known fossil sites. The relevance and challenge of study and preservation of this ancient ecosystem are equal to those of a modern ecosystem.
The surface topography of Fossil Butte is now covered by a high cold desert. Sagebrush is the dominant vegetation at the lower elevations, while limber pine and aspen occur on the slopes. Pronghorn, Mule deer and a variety of birds are commonly seen. Moose, elk and beaver are sometimes observed.
Introduction
Fossil Butte National Monument was established on October 23, 1972, in order to preserve fossil bearing rock formations. These rocks contain traces of plants and animals from a lake that covered the area over 50 million years ago. Many species of fishes, insects, birds and even crocodiles are wonderfully preserved, making the park’s fossils of international scientific importance. The 8,198 acre park is located just 15 miles west of the town of Kemmerer in southwestern Wyoming. At between 6500 feet and 8000 feet in elevation, its climate is that of high desert. Summers bring hot, sunny days and pleasantly cool nights. Winters are cold with moderate snowfall.
The park has a visitor center featuring a display of museum-quality fossils, a bookstore and an information desk. It is open year-round excluding federal holidays.
Animals abound at Fossil Butte. Herds of elk, pronghorn antelope, mule deer and even a few moose frequent the park. Smaller mammals such as jackrabbits, badgers, porcupines, coyotes and prairie dogs are resident year round. A variety of eagles, hawks and falcons have become increasingly common.
Nature & Science
Three ancient great lakes existed in the region of Wyoming, Utah and Colorado 50 million years ago - Lake Gosiute, Lake Uinta and Fossil Lake, the smallest. All are gone today, but they left behind a wealth of fossils in lake sediments that turned into the rock layers known as the Green River Formation, made up of laminate limestone, mudstone and volcanic ash. The fossils are among the most nearly perfectly preserved remains of ancient life in the world. Some of the most extraordinary of these fossils came from Fossil Lake, represented today by a flat-topped remnant of rock that stands where the center of Fossil Lake once was. Fossil Butte National Monument preserves that butte and its invaluable, fascinating record of the past. The fossils of Fossil Lake are remarkable for their abundance and the broad spectrum of species found here - more than 20 kinds of fish, 100 varieties of insects and an as yet uncounted number of plants. Paleontologists, the scientists who study fossils and private collectors have unearthed literally millions of specimens during the past 100 years. Many billions more still lie buried in the hills.
The fossils are remarkable for their detail. Many fish, for example, retain not only their entire skeletons, but their teeth, delicate scales and skin as well. And perhaps most remarkable of all is the story the fossils tell of an ancient life and landscape.
The scene 50 million years ago, during the Eocene Epoch of the Cenozoic Era, was quite different from that today. Fossil Lake, 50 miles long and 20 miles wide at its maximum, nestled among mountains in a lush green forest of palms, figs, cypress and other subtropical trees and shrubs. Willows, beeches, oaks, maples and ferns grew on the lower slopes and on the cool mountain sides was a spruce and fir forest. In and around the warm waters of the lake animal life was diverse and abundant. A broad range of fish inhabited the tributaries, shallows and deep water of Fossil Lake during its unusually long life of more than 2 million years. Gars, paddlefish, bowfins and stingrays, though they may appear primitive to some, still survive today, as do herring, perch and mooneyes. The lakeshore was alive with crocodiles and turtles; insects, dog-sized horses and early primates inhabited the land; birds and bats mastered the air.
Recreation
There are two interpretive hiking trails. Bicycles must remain on the roads and stay off of the trails for maintenance and safety reasons. There is no camping or overnight parking at the park.
Pets are allowed on trails, but must be under physical restraint at all times. Horse use is allowed in the Monument, but not on the trails. Riders must unload horses outside of the monument boundary.
During the winter, hiking and cross-country skiing are encouraged, weather permitting.
Traveler Facts
Contact Information
Fossil Butte National Monument
P. O. Box 592
Kemmerer, WY 83101-0592
Phone: 307-877-4455
Fax: 307-877-4457
Operating Hours & Seasons
Summer Hours 8:00am - 7:00 p.m. (June to August)
Winter Hours 8:00am - 4:30 p.m. (September through May). Closed winter Holidays.
Weather/Climate
Summer has warm days and moderate evenings. A light jacket is needed most evenings. Bring sturdy shoes needed for hiking and protection from sun is recommended. Spring, fall and winter can be very cold and you should expect snow and winter conditions. Light frosts are common on summer nights.
