2 eS eS — 
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NO. 4 GEOLOGY, WIND RIVER BASIN—TOURTELOT 7 
determinable because of its overlap on the topography of the moun- 
tains and because the base of the formation is not exposed within the 
area of figure 2. The top of the formation is everywhere an erosional 
surface. A composite section of the formation, pieced together from 
exposures between Cedar Ridge and Badwater Creek in T. 39 N., 
R. 89 W., indicates the presence of about 700 feet of strata assigned 
to the Tepee Trail formation (fig. 5). Correlations between the sec- 
tions are made somewhat uncertain by discontinuous exposures and 
by minor faulting. On the north face of Lysite Mountain, about 520 
feet of Tepee Trail strata are present. As much as 150 feet of the 
Tepee Trail is exposed in a continuous section at only a few places on 
the south side of the mountain ranges. The Tepee Trail formation 
consists of a sequence of green, brown, and gray strata rich in vol- 
canic material of andesitic composition.® The sequence can be di- 
vided into lower and upper members in exposures south of the moun- 
tain front, and an essentially nonvolcanic facies equivalent to both 
members directly adjacent to the mountains or in some reentrants 
within them (fig. 3). The lower member consists chiefly of green 
and brown rocks ranging in texture from conglomerate to claystone 
with some limestone. The upper member consists chiefly of gray 
and greenish-gray fine-grained strata overlain by tan siltstone. The 
nonvolcanic facies is made up of white and light-gray pebbly clay- 
stone and mudstone and is referred to as the white clastic facies. 
Green and brown member——The most characteristic lithologic 
features of the green and brown member of the Tepee Trail forma- 
tion are bedded sedimentary rocks rich in volcanic material and zones 
of conglomerate containing roundstones of hard andesite and hard 
tuff(?) embedded in a coarse-grained matrix of similar volcanic ma- 
terial. The colors are independent of the lithology, in large part, and 
at some places the green color seems to be a secondary feature, the 
nature and origin of which have not been studied. Along Badwater 
Creek (southwestern part of T. 39 N., R. 88 W.) and along Dry 
Creek (sec. 8, T. 39 N., R. 92 W.), light-colored siliceous fresh- 
water limestone is prominent in the upper part of the member. Just 
east of Snyder Draw (sec. 29, T. 40 N., R. 89 W.) is a small out- 
5In previous reports on this area, the Tepee Trail rocks have been called 
“tuffs.” Actually, the final depositing agent of nearly all the rocks was running 
water and the aerial transport of the volcanic material to the area, necessary 
for the use of the pyroclastic rock name “tuff” (Wentworth and Williams, 1932; 
see also Hay, 1952), can only be inferred. Although many of the strata are 
clearly resedimented tuffs that have been transported only a short distance by 
water, use of the terms proposed by Wentworth and Williams for water-laid 
volcanic material is more accurate and is followed in this report. 
