240 REPORT UNITED STATES GEOLOGICAL SURVEY. 
being walled by Archean rocks. In the debouchure of the cafon Mr. 
Perry found limited exposures of gray and brownish-gray soft sandstones 
in horizontal position, containing obseure fossils of apparently Tertiary 
facies. These presiimably Tertiary occurrences seem to indicate the 
pre-Tertiary existence of the mountain gorge in which these strata were 
deposited, and which latter were subsequently subjected to extensive 
glacial and fluviatile erosion, so that the present exposures may well be 
regarded as mere remnants of an originally extensively distributed Ceno- 
zoic formation. Some analogy may be recognized between the above 
exposures and the upper lignitic formation occurring in the Gros Ventre 
Basin, but the evidence, unfortunately, is too meager to more than sug- 
gest their possible identity with the latter horizons. 
Station XX VI was located on the uplifted Paleozoic ridge, midway 
between Jake’s and Torrey’s Creeks, at an actual altitude computed at 
10,269 feet, the crest culminating at a somewhat higher elevation a 
little to the south, or nearer Torrey’s Creek Cation. A fine view of the 
western or inner abrupt declivity of this mountain ridge was gained 
from the summit of Union Peak, extending southeast as “far as Station 
XXV, south of Campbell’s Fork. Cation, a distance of fourteen miles. 
The ereater elevation of the abrupt west: facing break is composed of 
‘Archean rocks, bearing above characteristic exposures of the Silurian 
and Carboniferous formations. The latter outcrops in long lines of low 
mural exposures, separated by intervals of more or less gentle talus 
slopes. As seen from the eastern edge of the summit plateau two or 
three miles north of Station XV, and ‘overlooking the profound depres- 
sion in the bottom of which lies’ the glacier-fed Jakelet that forms the 
source of Campbell’s Fork, the great sedimentary mountain ridge is 
shut out from view by lotty iter vening Archean walls. This part of 
the range is frightfully gashed by erosive agents, and in the chasms 
that reach up into the high summit still linger not insignificant remnants 
of glaciers, which above emerge into the snow-fields that envelop ex- 
tensive areas over the northeast slope of the summit. 
Between Torrey’s Creek and Little Wind River Canons the mountain 
flank preserves the same geological character as noted to the northwest 
of the former stream. But the caiions that pierce this part of the range 
afford more complete sections of the Mesozoic rocks, owing to the fact 
that the mountain border to the south has suffered to a much less degree 
from the effects of the denuding agents, which to the north, in places, 
barred the Palezozoics to the base of the mountain. ‘Although lying to 
the east of the limits of the present district, opportunity was “offered for 
visiting some of the more important cations cutting the great sediment- 
ary ridge, and the securing of an amount of interesting data bearing on 
the general structure of the mountain flank. In compliance with the 
request of Dr. Hayden, a brief account of the observations in this 
quarter, including both the mountain flank and such portions of the ba- 
sin area as came under hasty examination, is subjoined. 
Hight miles southeast of Torrey’s Creek, Campbell’s Fork issues from 
the mountains. Its sources, which have ‘already been alluded to, lie 
well within the territory of ‘this district, and flowing north of east it 
joins Wind River, after a course of about sixteen miles, at a point six 
miles below the mouth of N orth Fork. For fully three- ‘fourths of this 
distance the stream traverses a deep mountain gorge, the upper half ly- 
ing exclusively in the Archean area, the lower portion cutting across 
the outer mountain ridge, where the uplifted sedimentaries are shown 
in escarpments hundreds of feet in height. Just below the debouchure 
the stream is dammed by low, transverse barriers, doubtless of glacial 
ee 
