210 REPORT UNITED STATES GEOLOGICAL SURVEY. 
ledges inclining northeastward. Their reappearance was not observed 
on the steep southwest flank of the mountain immediately under the 
station, where the only sedimentary beds found are Carboniferous lime- 
stones with characteristic fossils, which outcrop in low, glaciated bosses, 
and dipping toward the mountain, whose foot is here buried in the débris. 
West of this, however, the quartzite, succeeded by the rusty-drab, even- 
bedded Quebec group limestones, is Seen rising upon the mountain flank, 
and in outlying Tidges the gray Garboniferous limestones recur. Itis in 
the interval lying between “the latter and the Triassic “ red beds” oceur- 
ring in the Hoback Canon ridge, that the singular red conglomeritic 
deposits occur, also dipping toward the mountain, and which hide from 
view the older rocks. This conglomerate is made up of abraded rock 
fragments, contributions from all the older rocks, including those of as 
late date as the Jura- -Trias, and possibly the Laramie formations, from 
which its relatively recent age is inferred. It seems highly pr obable 
that the interval alluded to marks the site of extraordinary geological 
disturbance, such as might occur along the line of impingement of two 
distinct axes of upheaval. 
The mountain is here much eroded, showing peculiarly weathered 
prec ipitous Archean ledges terminated i in extensive taluses of sliding 
débris. Itisan exceedingly picturesque locality, presenting tltose typical 
forms in mountain sculpture strikingly in contrast with the architectural 
forms into which the later sedimentary formations are wrought. Mr. 
Clark brought from the peak of Station XII fragments of quartzite, 
showing that even on this height the Archean is barely denuded of its 
Primordial covering. Mr. Perry, who also ascended the mountain, re- 
ported it made up of contorted gneissic rocks, quartz, feldspathic and 
hornblendic, traversed by quartz veins, and showing a well-marked anti- 
clinal, strike east-west, trendinground to northwest and southeast, with 
inclination of 25° to the horizon. To the northeast the slopes are com- 
paratively gentle, descending into the depression intervening between 
this and the north fold—a region filled with denuded, rocky inclines and 
sloping sedimentary tables, the same as described in the report on the 
Téton District, 1877. This depression drains southeast into the Hoback 
and north into the Little Gros Ventre.’ The latter quarter was reported 
upon the previous season. 
A couple of miles to the southeast of Station XII this south ridge is 
crested by Silurian formations, dipping gently northeastward, anda little 
farther on a heavy mass of Carboniferous limestone rises high up on a 
short spur in the south flank, the strata dipping toward the mountain, 
or N. 37° E., at angles of 20° to 30°, or more. The latter show bluish- 
gray, Spar- -seamed, cherty limestone and light buff, brecciated, impure 
limestone layers, containing numerous examples of a small zaphrentoid 
coral, a large Syringopora, and crinoidal remains. In the opposite side of 
the amphitheater, to the east, the quartzites and Quebec limestones are 
seen steeply inclined off the foot of the mountain and crowning the crest 
in isolated, monumental masses which have been but little disturbed from _ 
their horizontal position in the elevation of the mountain. The middle 
portion of the abrupt south front of the ridge shows a belt of denuded 
Archean rocks separating the lower and upper sedimentary occurrences. 
At this point the Carboniferous limestones have been swept away, but 
the remnant of Quebec limestone is flexed up in a sharp synclinal, a mere 
fragment of the south flank of the trough remaining. 
The Primordial quartzite here exhibits the same appearance noted in 
- this horizon to the west. It is a dark brownish-red to rusty buff, lami- 
nated rock, steeply dipping southward, and rests immediately upon the 
