Where is Fossil Butte National Monument?
Fossil Butte National Monument is a national monument in the U.S. State of Wyoming. It preserves a fossil deposit, Fossil Lake, from the Eocene, about 50 million years ago.
The Reserve was established in 1972 after the deposit was explored from the 1870s onwards and finds were commercialised over several decades. It is managed by the National Park Service.
The fossil finds consist almost exclusively of aquatic life forms, mostly fish. Besides crocodiles, soft turtles, two species bats, some dragonflies and other species. The finds are deposited in the Green River Formation, sedimentary rock of the large lake landscapes, which consists of sandstone and siltstone with stored coal and oil shale. The particularly interesting layers are limestone and dolomite, which are found here in such a fine composition that they have not only preserved bone structures, but also soft parts of the fossil Fauna. The best preserved finds lie in the so-called 18-inch layer, a limestone layer.
In the 1870s, near-surface coal was developed to supply the railway. The Miners made the first fossil finds.