Fossil Butte National Monument is near the geographical center of Fossil Basin. The basin itself is located in the extreme southwestern part of Wyoming in Uinta and Lincoln counties, near the Utah-Idaho border ([Fig. 2]).
The monument is situated about 10 miles west of Kemmerer, Lincoln County, Wyoming ([Fig. 3]). U.S. Highway 30N runs just south of the monument as does the Union Pacific Railroad line to Oregon. The abandoned town of Fossil is also immediately south of the monument.
The Kemmerer and Sage quadrangles of the United States Geological Survey cover the entire monument and the surrounding area.
HISTORICAL BACKGROUND OF RESEARCH
The principal rocks involved at Fossil Butte are the Green River and Wasatch formations. The first published notice of these two rock units was by Hayden (1869). Although short, Hayden’s descriptions were the basis for later refinement of the stratigraphy of the Green River and Fossil basins. Hayden also mentioned the quantities of fossil fish from the Green River Formation.
The work done by Hayden was conducted under the auspices of the U.S. Department of the Interior, Geological and Geographical Survey of the Territories. The survey lasted from 1867 to 1878, during which time Hayden and his associates published annual reports of their findings.
In the 1870 report, Hayden (1871) mentioned the discovery of the Petrified Fish Cut. This cut is located on the main line of the Union Pacific Railroad about 2 miles west of Green River, Wyoming. A. W. Hilliard and L. E. Rickseeker, employees of the Union Pacific Railroad, discovered the cut and obtained many fossil fish which they turned over to Hayden.
Previous to Hayden, rocks now known as the Green River and Wasatch formations were occasionally mentioned in the various diaries, journals, and reports of early missionaries like those of S. A. Parker or those of explorers like Fremont (Knight 1955).
Fig. 1. Paleocene-Eocene lake system (after Schaeffer and Mangun 1965).