NO. 4 GEOLOGY, WIND RIVER BASIN—TOURTELOT 3 
with some feldspathic sandstone and much gypsum” is the only recog- 
nition of the younger Eocene rocks until Wood, Seton, and Hares 
(1936) announced the discovery of fossil mammals of late Eocene age 
from a locality on Badwater Creek (loc. 3, fig. 2). Love (1939, 
p. 78) compared the strata here with the Tepee Trail forma- 
tion of late Eocene age in the Absaroka Range, where the formation 
consists of flows, breccias, and tuffs. Wood, Seton, and Hares recog- 
40 MILES 
Fic. 1.—Sketch map showing location of area discussed in this report. 
nized the fault that separates the strata of middle(?) and late Eocene 
age on the north from the Wind River formation on the south. In 
1944, investigations of the geology of the area were begun by the 
U. S. Geological Survey to establish the structural relations between 
the Wind River Basin and the bordering Owl Creek and Big Horn 
Mountains and to map the geology of the area (Tourtelot, 1946, 1948, 
1953).* Considerable emphasis was placed in these investigations on 
the Tertiary stratigraphy as a basis for interpreting the geologic his- 
tory of the area. The fauna described by C. L. Gazin in Part 2 of 
this report was discovered during this work. The fauna was enlarged 
by collections made by A. E. Wood (1949) and by C. L. Gazin and 
Franklin Pearce in 1946 and 1953. 
* Data from these publications are included in this report without direct cita- 
tion, for the most part. 
