342 REPORT UNITED STATES GEOLOGICAL SURVEY. 



whicli show here and there in reddish fragmental ledges. The country 

 is covered with a brownish-buff soil, which sustains a good growth of 

 excellent herbage. Little streams of pui'e water flow down from the 

 range, opening into pretty intervales bordered by willows and ponded 

 by beaver-dams. We were inchned to imagine it a sort of Arcadia, in 

 vrhich the rough duties of our every-day life were blended with unex- 

 pected exhibitions of latent sentiment, transforming the camp into sem- 

 blance of home, which with regret Ave daily abandoned, oidy to find the 

 next spot equally- jileasantly selected and our evening board decorated 

 with chai-miug floral displays, the welcome ahnost daily prepared us by 

 our young men. 



Between Stations YII and YIII the crest of the range trends more to 

 the southeast, and is broken down in a wide recess which opens south- 

 westerly into the Blaclvfoot Valley, and which is filled with smooth, wave- 

 lilce hills, which rise in successive benches and culminate in trachyte- 

 crowned suuunits but little lower than the crest of the main range. One 

 of these eminences, situated in the mouth of the recess, and nearly in 

 Ihie with and almost midway between Stations VII and VIII, consists 

 of brownish-red and drab trach.-^'lic rock, which occurs both in large 

 block's, rounded by atmos])heric action, exfoliating in concentric layers, 

 and in tlun, even-bedded layers, which gently incline north-northeast. 

 The break drains west by Elder Creek, and south by a similar affluent, 

 GraA'cl Creek. To the northwestward, the sections exposed in the ra- 

 vines show the limestone strata in nearly horizontal position, or gently 

 inclined from east to west ; but this appearance is due to the course of 

 the canons following nearly the direction of strike of the ledges, which 

 are elsewhere observed to dip in a general southwesterly direction at 

 angles of from 25^ to G0°. Ascending the southern continuation of the 

 range, at a i)oint to the northwest of Station VIII, where Gravel Creek 

 enters a part of its course sustained by a huge retaining- wall of lime- 

 stone, through which it breaks near the foot of Station VIII and flows 

 out southwesterly into the valley, the Carboniferous beds again appear 

 in force, grayish-blue, spar-seamed limestone, with crinoidal columns 

 and Zaphrentis, dipping- W. 5° S., at an angle of 30°. The same beds 

 form the wall along the west side of the creek, in which they appear in 

 horizontal lines conforming to the strike of the strata, and weathered 

 in picturesque castellated forms, pierced with caverns and apertures. 

 The mountain slopes steeply to the stream, its face buried beneath the 

 angular debris fallen from above. A little farther to the southeast these 

 strata have trended round more to the west, dipping 35°, S. 35° W. In 

 the saddle, a short distance northwest of Station VIII, the axis of a fold 

 lies near and parallel with the crest, the beds dipping on the one hand 

 15° to 25°, N. 25° to 35° E. ; and nearer the station the crest is formed of 

 ledges abundantly charged with a form of Lithostrotion, Zaphrentis, &c., 

 and dip S. 30° W., at an angle of 40°. Standing on any part of the 

 crest in this vicinity, the wavering direction of the strike of the rocks 

 is plainly traced, curving in and out, the angle of inclination gradually 

 steepening, until, on the southwest flank, it reaches nearlj^ G0°, S. 50° 

 W., but so variable, even in this short distance, that only the aggregate 

 of many observations give the mean of the rate of dip and direction of 

 strike of the ledges which make up the mountain ridge. Descending 

 from Station VIII, in the south end of the low ridge confining Gravel 

 Creek to the foot of the mountain for a part of its course, and just south 

 of the ]:)oint where the stream forces a passage through to the valley, 

 an interesting example of cleavage is seen, whiijli at first sight might be 

 mistaken for" the bedding. The limestone rises up in a steep face, front- 



