260 = REPORT UNITED STATES GEOLOGICAL SURVEY. 
In the uplands to the east the same variegated series occurs over a wide 
belt extending down the middle of the basin, and is overlaid by ob- 
scurely exposed deposits of drab clays and soft yellow sandstones. Just 
below the Du Noir, the north side terrace closely approaches the stream 
which has cut a narrow gorge in the tiited Carboniferous sandstones 
reclining on the flank of the Wind River Mountains, as described in a 
preceding page. The relations of the basin Tertiary deposits to the 
Paleeozie series in the mountain-flank at this locality are concealed by 
drift accumulations mantling the terrace. But in the north side of the 
expansion into which the valley opens below the narrows, the variegated 
deposits are exposed on an extensive scaie in the deep recess which here 
penetrates the upland; the soft materials of which they are composed 
readily yielding to the elements, which have wrought with wonderfully 
intricate picturesque effects in the sculpture of the barren bluffs that 
inclose this side of the valley. 
A few miles below the narrows, the uplands again approach the stream 
which here traverses a narrow passage cut into the dark red sandstones * 
of the Trias, which latter form the basis of the outlying terrace along 
the foot of the Wind River Mountains. A limited exposure of Jurassic 
strata occurs in the bench on the north side of the stream, upon which 
rest the nonconformable variegated Tertiary beds. The latter here rise 
up into a prominent headland, 600 feet or more in height, which was 
utilized for topographic purposes the previous season (Station LI, Té- 
ton division). These deposits here consist of alternating bands of pale- 
red and greenish-drab clays, with irregular or local thin layers of gray 
and y ellow sandstone. ‘The eminence is covered with a thickness of 10 
to 30 feet of brown earth and drift materials resting upon the planed- 
off surface of the variegated beds. The latter here incline to the north- 
eastward at an angle not exceeding 5°; the underlyins Jurassic beds 
dip in the same direction at an angle of 15° to 20°, the nonconforinity 
being marked as seen in the natural exposures ata distance. Itis prob- 
able a thickness of at least 1,000 feet of these deposits is seen in the 
picturesquely eroded area of their occurrence here alluded to, while their 
total vertical extent may be found to exceed this estimate. The com- 
paratively limited unexposed space intervening between the Jura and 
variegated Tertiary at this locality is wholly insufficient to admit the 
heavy series of yellow sandstones and clays of the lignitic series which 
higher up the valley were found underlyi ing the variegated deposits. 
Hence, it is reasonably inferred that the lignitic formation was here 
denuded prior to the deposition of the variegated beds, which at this 
locality rest immediately upon the unconformable and also extensively 
denuded Juarissic strata. 
Some notion of the distribution of the various geologic formations of 
the region may be gained from the eminence on which Station LIT (1877) 
was located. The banded Tertiary deposits have extensive areal dis- 
tribution to the north and east. The great sedimented volcanic ridge, 
constituting the Sierra Shoshone of Captain Jones, is traced from Tog- 
wotee Pass, eastward, along the northern rim of the basin, terminating 
in a group of lofty pinnacles lying to the east of the sources of North 
Fork Wind River, and which are probably the Washakee Needles. Irom 
the latter mountain ridge, the Owl Creek Mountains are separated by a 
gap, and at their base lies a massive outlying bench in which an enor- 
mous thickness of similar variegated deposits is visible. The valleys 
of Horse Creek and North Fork are excavated in these deposits—their 
fringes of cottonwood and green shrubs presenting a pleasing contrast 
to the environing red-striped barren hillsides, in appearance a semi- 
badland region, destitute of more than scant pasturage. 
