186 REPORT UNITED STATES GEOLOGICAL SURVEY. 
bowlders, including metamorphic fragments, which were derived from 
the Gros Ventre Mountains. The expansions of the valley receive con- 
siderable affluents from the north, and this section marks the axis of a 
syneclinal depression which is filled with the Triassic “red beds.” A 
few miles above the entrance to the cation the strata are much disturbed, 
and in the space beyond, lying between this ridge and the southern foot 
of the Gros Ventre Mountains, the continuity of the Mesozoics is lost 
beneath accumulations of more recent origin. 
In the low nerthern continuation of the ridge the sedimentary for- 
mations apparently trend round more to the west, where they approach 
nearest to the south flank of the Gros Ventre Mountains. ‘There is evi- 
dence of much disturbance in this quarter, the Triassic ‘‘red beds” being 
steeply upraised and resting upon deposits referred to the Upper Carbon- 
iferous. The latter here show a heavy ledge of gray, rusty weathered, 
fragmentary limestone, locally showing a tendency to concretionary 
structure,as also magnesian in composition. The bed outcrops in a 
sharp ridge between two northern afiluents of the above-mentioned 
stream, and dips southwestwardly at angles varying from 45° to 80°. 
In lithological character and composition the ledge resembles horizons 
in the uppermost or Permo-Carboniferous division, as elsewhere devel- 
oped in this region, although no fossils were recognized at this locality. 
The “red beds” here show 500 to 1,000 feet of the inferior portion of 
the series, consisting of alternations of deep red and thinner gray, lami- 
nated arenaceous shales and sandstones. These deposits inclose bands 
of reddish-stained, vesicular calcareous rock, which weathers with arough 
surface, recalling the tufaceous-like limestone layers interbedded in the 
Triassic sandstones on the east flank of the Wind River Mountains. 
The latter ‘“‘red bed” series forms a belt, the trend of which apparently 
identifies the fold at the present locality with the first abrupt break on 
the east of the Carboniferous belt in the Hoback Canon section already 
noticed. The position of this red belt is indicated in the steep slopes, 
both by the red color imparted to the soil by the disintegration of the 
red arenaceous deposits and the luxuriant herbaceous growth which this 
soil sustains in mountainous regions. 
As already intimated, the eastern flank of the latter Mesozoic fold 
north of the little stream above described is obscured by later deposits. 
But in the section between this stream and Hoback Cation, ascending to 
Station III, which occupies an eminence in the midst of this area nearly 
10,000 feet in altitude, the following observations weremade: Westof the 
outilanking eastern anticlinal ridge, on crossing the synclinal, the calca- 
reous indurated shales, drab limestones, and chocolate-red arenaceous 
shales composing the Jura, succeeded below by the Triassic sandstones, 
outcrop at intervals in the outlying spur ridges at the foot of Station 
IIf. These deposits dip to the eastward, but in the space lying between 
the abrupt spur ridges and the main mountain group the strata are ob- - 
securely exposed; so that itis not clear how intimate the western border 
of the Mesozoic fold here corresponds toits appearance 3 or 4 miles to 
the south in the Hoback Cation section. 
In the summit of Station IIT the strata dip southwest at an angle of 
30°, the direction and angle of inclination varying considerably even 
within short distances. The crest shows a ledge of gray sandstone, in 
places slightly caleareous and laminated, underlaid by red, indurated 
arenaceous deposits. The high shoulder on the east, however, exposes 
Similar gray and brownish red sandstones, dipping 25° northeastward, 
and a few hundred yards south of the station the same ledges incline 
northwest at the same angle. It is apparent that Station III ridge is 
