The 8,198 acre park is located just 15 miles west of the town of Kemmerer in southwestern Wyoming. At between 2000 and 2500 meters (6500’ and 8000’) 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. There are also two groomed hiking trails.

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.

Fees and Restrictions
There is no entrance fee at the Monument.

Licensed motor bikes, trucks, and automobiles are permitted in the Monument, but are restricted to designated roads and operators must be properly licensed. Bicycles must also 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. During the winter, hiking and cross-country skiing are encouraged, weather permitting. Snow machines are not permitted within the Monument boundaries.

The Fossils
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.

Ideal Conditions for Fossil-Making
What events led to the preservation of so much of Fossil Lake’s life as fossils? No one knows for sure, but after careful study scientists have developed theories to explain the process. One essential ingredient for preservation, they believe, was rapid burial in calcium carbonate, which precipitated out of the water and fell like a constant gentle snow on the bottom of Fossil Lake. Whatever sank to the bottom - dead fish, fallen leaves - was covered by this protective blanket. Year after year for hundreds of thousands of years, this reoccurred. Some of the most perfectly preserved fossils come from the deep-water sediment layers of whitish to buff-colored calcite limestone alternating with brown oil shale commonly called the 18-inch layer. The fossils are generally adult fish. An equally important fossil-bearing layer comes from nearer the lake shallows and is composed of lighter colored limestone with faint lamination that splits easily due to the lack of organic material. Thus, its name: the split-fish layer, which averages 6.5 feet thick. Here one finds younger fish and species that would have survived better in near shore shallows - crayfish and stingrays, for example.

Unsolved Mysteries
While many of Fossil Lake’s animals and plants probably died natural deaths, on several occasions huge numbers of fish were killed suddenly. These die-offs are recorded on great slabs of the Green River Formation called mass mortality layers. What killed these fish? A superbloom of blue-green algae that emitted poisons into the water? A sudden change in water temperature or salinity? All of these? Ongoing research may solve the mystery.

Fossil Collection Issues
Fossils: A Part of Our National Heritage
Fossils have been pondered and discussed since the time of the early Greeks. Throughout human history, fossils have been perceived as objects of awe and wonder, and scorned as tricks of the Devil. As we have come to understand earth history more fully, fossils have proven valuable tools for interpreting ancient climates and understanding the development of life forms throughout earth history.

When the science of paleontology was first established, fossils were often studied “out of context.” Little attention was given to the study of ancient environments in which the fossil had once resided or the context in which the organism was deposited. With the increased sophistication of paleontology as a science, fossils are no longer considered isolated objects but as elements of a complex continuum of ancient ecosystems.

When fossils are collected by researcher, careful documentation is made of their location, their place in the geologic record, and the type of depositional environment. Also, any relationship with surrounding ancient organisms is noted. Paleontologists are now asking questions about how the earth’s climate has changed through time and what forces were at work to cause the mass extinctions that occurred in the past.

Because fossils can provide such a wealth of information, they are considered an important national treasure to protect. On federal lands, the collecting of vertebrate fossils is allowed only for research purposes and the collectors must be associated with some type of public institution, usually a museum or university. The purpose of this regulation is to ensure that vertebrate fossils are collected with as much information as possible and that they remain in the public trust. Different regulations pertain to state lands, and private lands are unregulated.

Fossil Collecting in Fossil Basin
Fossil Basin contains some of the most complete and well-preserved fossils in the world. Fossil Basin also contains the remains of an ancient ecosystem. These detailed fossils and their ecological relationships have been studied extensively by researchers since the 1870s. Around the turn of the century, the first commercial quarriers “set up shop” in Fossil Basin. They collected and prepared fossil fish and sold them to private collectors and museums around the world. Today, the Bureau of Land Management (BLM) and Fossil Butte National Monument, a unit of the National Park Service (NPS), protect a portion of the land within Fossil Basin. Commercial quarrying activity in Fossil Basin occurs on private or state leased lands.

The State of Wyoming has developed a permit system through the State Land Commission that allows commercial quarriers to quarry for vertebrate fossils in the Green River Formation on State lands. However, they must report and relinquish any vertebrate fossils that are not one the seven most common genera (Knightia, Diplomystus, Priscacara, Mioplosus, Notogoneus,and Amphiplaga. The uncommon genera are sent to the University of Wyoming Museum of Geology where they are prepared and further studied.

Individuals who collect on private lands are not obligated to turn in rare or unique specimens. They can sell their fossils without restriction. However, many private collectors donate fossils to public institutions.

The Value of Protecting Fossils on Public Lands

• All fossils collected on public lands are documented and accounted for. Within the National Park Service, fossils are curated and available for loan to other institutions.
• Researchers with collecting permits are able to study paleontological deposits and purse pertinent questions on ancient environments, evolution, and paleoclimates.
• Fossils within the National Park Service are made available to the public through exhibits and interpretation. Specimens not on exhibit are accessible through study collections and loans.

Above article courtesy of National Park Service.