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).
[Illustration: Fig. 1. Paleocene-Eocene lake system (after Schaeffer
and Mangun 1965).]
[Illustration: Fig. 2. Geographic features of southwest Wyoming and
adjacent areas (from Oriel and Tracey 1970).]
[Illustration: Fig. 3. Physiography of the Fossil Butte National
Monument region (from U.S. Department of the Interior 1964).]
Hayden’s report (1871:425-437) included a description of the fish
fossils from Petrified Fish Cut by E. D. Cope, a vertebrate
paleontologist. Several years earlier Leidy (1856), another
paleontologist, described a fish from an unknown locality in the Green
River Formation.
Hayden divided this survey area into several districts. The Green River
district was put in charge of A. C. Peale. Peale’s (1879:535) report
contained the first geologic description of Fossil Butte itself, as well
as a short discussion of the fish fossils obtained there. The
description of the butte is quoted here:
... In the lower part of the bluff from which these specimens are
taken, the bright coloured beds of the Wasatch are seen outcropping,
although the entire section cannot be seen, as their softness causes
them to weather so that the debris conceals the strata. The fossils
are found at several horizons in the shales. Near the top of the bluff
is a band of hard, bituminous, or oily shale, which burns rather
freely with a strong bituminous odor.... It is brownish-black in color
and on the weathered surfaces a bluish white....
The next major publication dealing with Fossil Basin was that by Veatch
(1907). He mapped the rocks in certain areas of the basin in an attempt
to bring a semblance of order to Hayden’s (1869) broad stratigraphic
descriptions. His work resulted in the designation of most of the rock
units in Fossil Basin from Jurassic to Recent.
Schultz (1914), an associate of Veatch, published a paper dealing with
the structures to the north and east of Fossil Basin. This helped to
delineate the features surrounding and forming the basin.
Subsequent work on the geology of southwest Wyoming mainly has been
concentrated on the Green River Basin just east of Fossil Basin.
Significant work on Fossil Basin has been done by Rubey et al. (1968a,
b) who mapped the northern part of the basin, and by Oriel and Tracey
(1970) who have published results of the latest study on the
stratigraphy and age of the rock units in Fossil Basin. This latest work
is the culmination of many years of study and incorporates and refines
data presented in shorter, earlier papers.