sr. john.] SECTION THROUGH STATION XXIV. 381 



the opposite side at an angle of 30°, X. 35° E., and again gently rising 

 to the northeast, where it forms a low bench outcrop 50 to 75 yards 

 from the axis of the fold. A thickness of 20 feet is exposed. 



34. Bed shales, space 40 yards. 



35. Drab, fragmentary limestone, obscure outcrop. 



36. Defrm-covered slope, 25 yards. 



37. Uneven heavy-bedded buff limestone, apparently interbedded or 

 associated with drab limestone, 20 to 30 feet exposed. The buff ledge is 

 variable in inclination, dipping at one point 28°, W. 45° X., and a few 

 yards to the east changing to X. 30° to 45° E. at an angle of 30° to 35°, 

 in the direction of the general slope, and passing under the trachytic 

 ledges which here rest on the crest of the ridge. The buff limestone 

 much resembles a tufaceous spring deposit. 



38. Drab and chocolate-colored trachytic debris in crest of spur-ddge 

 apparently filling a gully or sag 200 to 300 yards across. 



39. Keddish-gray and buff, hard, obliquely-laminated quartzitic sand- 

 stone, with slickenside surfaces and much broken up by joint and cleav- 

 age structure. Forms a heavy ledge, dipping 25° to 45°, S. 30° to 00° W. 



40. Slope, with sandstone debris in low bench midway, 400 to 500 

 yards. 



41. Debris of drab, indurated calcareous shales and nodular limestone, 

 in brow of steep declivity. 



42. Unexposed, 100 yards. 



43. Heavy ledge of light and dark drab limestone, 20 feet exposed, in 

 prominent transverse ridge. Dip 45°, S. 50° W. 



44. The main crest of the spur from the above ledge is composed of 

 trachytic rock, which sweeps down into the valley, terminating abruptly 

 in high bluffs on the Snake just above the entrance to the " lower cafion." 

 The undulating crest of the ridge is covered with considerable quantities 

 of water-worn pebbles and bowlders of sedimentary and other rocks. 



45. Crossing over to the next spur-ridge on the southeast, in the slope 

 perhaps half a mile from the last limestone ledge, 43, there appears the 

 debris outcrop of tight bluish spar-seamed limestone, which, lithologic- 

 ally, bears a strong resemblance to the Carboniferous limestones, although 

 no fossils were here discerned conclusively demonstrating their age. 



40. The above ledge is followed by a heavy ledge of pinkish-gray, 

 laminated quartzite, dipping 50°, S. 55° W., which forms a narrow abut- 

 ment ridge across the foot of the spur through which the little brook has 

 cut a picturesque canon passage just before it emerges into a miniature 

 basin and flows out to join the Snake half a mile below. 



The little basin at the foot of the above-mentioned spur on the edge 

 of the Snake Valley, a few hundred yards distant from the quartzite 

 wall, is partially hemmed in by a low conical hill 200 to 300 feet in height, 

 which shows weathered masses of flesh-colored and drab trachyte 

 protruding in the upper slopes, similar to that observed in the trachytic 

 continuation of the main spur a mile or so to the north. The volcanic 

 ledges here apparently rest upon a deposit of soft drab earth, but so 

 imperfectly exposed as not to show clearly its character. It resembles 

 the earthy material found in connection with the late Tertiary deposits 

 and superimposed trachytic mantle, as seen at the before- mentioned 

 localities in the vicinity of Station XXX, and elsewhere in the valley of 

 the Blackfoot. The water-worn drift material alluded to under Xo. 44 

 of the foregoing section, is found scattered plentifully over this little 

 butte, and chiefly consists of quartzite bowlders, with few of limestone. 

 Similar occurrences of this erratic material were subsequently met with 

 higher up the valley. 



