370 EEPORT UNITED STATES GEOLOGICAL SURVEY. 



112. Yery hard, dark blue, chocolate-stained, spar-seamed sandstone, 

 5 feet exposed ; dip 35°, I^T. 40° E. 



113. Low ridg-e, covered with the rusty brown vesicular obsidian lava, 

 also here occurring in abraded masses, 60 yards. 



114. Slope, showing red shales and obsidian fragments, 125 yards. 



115. Partially metamorphosed, hard indurated, chocolate-colored 

 shales, dipping northeastward, but much obscured by cleavage, passing; 

 up into red shales, 250 yards. 



IIG. Dove-colored or light drab, fragmentary, sometimes earthy lime- 

 stone, apparently forming a heavy bed, of which a thickness of 10 to 

 20 feet is exposed ; overlaid by harder, rough-weathered darkish gray 

 and drab, heavier bedded limestone, with obscure fossils. The rock, in 

 places, weathered light yellowish drab, and is intersected by thin seams 

 of chalcedony. Dip north-northeast, at an angle of 30°, more or less, and 

 flagging the northeast face of the mountain. 



Station XX affords a fine view of the mountain summits to the soutli 

 and southwest, but to the north higher crests shut out the view of the 

 northern end of the range. Looking down the great spur-like ridge 

 which descends along the north side of Fall Creek Canon, we gain a 

 pretty clear knowledge of the lithological characters of the rocky strata 

 and their distribution in the space embraced between Station XX and 

 the nearest point on Snake Eiver, six miles to the northeast, just above 

 the entrance to its lower caiion in the basalt. Without presuming to 

 give the actual dip of these strata, which the distance did not allow of 

 satisfactory determination, their appearance has been incorporated in 

 the diagram of the above referred to section, and which may be briefly 

 noticed as follows : Outlying the summit of the station on the northeast, 

 and beneath which its limestone mail passes in its northeasterly inclina- 

 tion, the first break or double parallel ridge shows (117) a heavy deposit 

 of red beds, largely composed of soft materials, with beds of brown and 

 red sandstone. Xext beyond, in a narrow succeeding ridge, is seen 

 (118) a series of light drab bands, merging below into the reddish shales 

 of the preceding. Xext occurs a wide and very broken belt, one to two 

 miles across, in which appear (110) heavy deposits of red-colored beds ; 

 then succeeds a lower and narrower ridge, made up of (120) light-colored 

 beds, followed by (121) a partially exposed red-bed ridge, apparently 

 lying near the valley-side, south of the Snake. The strata of the two 

 first series (117, 118) evidently dip with the limestones (IIG) in Station 

 XX ; but in the ridges beyond it was impossible to determine more than 

 the general lithological peculiarities of the strata, which were seen to 

 /cross the spur in parallel bands. However, to the north we were able 

 to extend our examinations into the belt of deposits here referred to, and 

 the resu.lts will be alluded to presently. 



In passing up the south spur of Station XX, at a point about a mile 

 from the station, an interesting exposure of the same series of strata 

 shown in the foregoing section occurs in the northwest side of the gulch. 

 Tlie limestone and sandstone beds, 85 to 89, and others, have the ap- 

 pearance of having been quite overturned, so that these beds as sliown 

 in the section actually occupy an inverted position. Farther up the 

 gulch, here and there exposures of light gray limestones are traced in 

 the upper slopes, their outcrop nearly horizontal or gently inclined north- 

 erly, as though they constituted part of the roof of a broad-topped anti- 

 clinal fold, in the southern flank of Avhich the strata were toppled over 

 past the vertical, while in the oi)i)osite or northern flank they hold their 

 natural relative position, where they are overlaid in order by the super- 



