238 REPORT UNITED STATES GEOLOGICAL SURVEY. 
strata, is pierced by numerous water-courses, whose deeply eroded cafions 
break the continuity of the great sedimentary ridge, revealing its struet- 
ural features in a series of most remarkable natural rock sections. The 
meager observations made above Warm Spring Creek have already re- 
ceived brief mention, and the following notes are based on observations 
made along the mountain front below that locality, extending to the 
eastern boundary of the district a few miles below the mouth of Tor- 
rey’s Creek. However, much interesting data was gained relating to the 
detail geology of the great eastern foreland between the latter point and 
Camp Brown, which, although outside the limits of this district, will be 
introduced in the order of their occurrence in journeying southwards 
along this side of the mountains. 
A few miles below Warm Spring Creek and about a mile distant from 
Wind River the foreland slope is interrupted by a rather prominent 
ledge of rusty weathered rock, having the appearance of a trap-dike as 
seen from a distance. It was found, however, to consist of a steeply 
tilted mass of middle Carboniferous sandstone, at one point dipping 
about northeast at an angle of 80°. It is made up of buff and reddish 
partially metamorphosed sandstones, including softer portions. The 
steep slope below is strewn with fragments of dark buff and drab lime- 
stones and chert, containing Productus and Spirifer, belonging to the up- 
per division of the Carboniferous. On reaching the foot of the steep 
declivity the Triassic “‘red beds” are encountered, extending thence in 
the terrace bench to Wind River, where they form low mural exposures. 
The gentle inclination of the latter deposits might almost be regarded 
as evidence of non-conformity, an appearance which is doubtless due to 
the abrupt flexure of the strata at this point, and the erosion of the 
softer superimposed deposits over the steep acclivity down to or below 
the line defining the abrupt spring of the uplift. 
Just below, on the opposite side of Wind River, and perhaps three or 
‘four miles below Warm Spring Creek, Station LII of 1877 was located 
on an eminence of the Wind River Tertiary, which here closely ap- 
proaches the stream. The above-mentioned Trias ‘‘red beds” reappear 
in the outlying bench at the foot of the Tertiary plateau, where they are 
in turn overlaid by a few feet thickness of the inferior strata of the Jura, 
resting upon the soft light-colored sandstones, &c., composing the beds 
of passage between the Jurassic and the typical “red beds” of the Trias. 
The Jura appears in a bench about 300 feet above the river, and is uncon- 
formably overlaid by the variegated or banded pale-red and greenish- 
drab arenaceous clays of the Wind River Tertiary, which culminate in 
the before-mentioned station promontory at an elevation of 600 to 650 
feet above the stream. The Jura and inferior strata at this locality pre- 
sent the following section: 
Section at Station LIT (1877), north side of Wind River. 
a. Triassic “red beds,” consisting of deep-red and greenish-drab in- 
durated gritty layers, upper measures concealed in terrace surface. 
b. Green clays, with thin streaks of deep-red indurated gritty layers, 
10 feet exposed, at elevation of about 275 feet above river. 
e. Soft, thin-bedded yellow sandstone, with red and gray streaks, 30 
feet; overlaid by soft whitish sandstone, 40 to 50 feet. 
d. Greenish-blue marly clays, with layers of dirty gray-buff lamina- 
ted and thin shaly limestone, 25 feet +. 
_ @, Drab-gray, heavy bedded fragmentary limestone, 4 to 5 feet. 
J. Light marly shales, 25 feet +. 
