sr. jornr.] SECTION — WILLOW CREEK BASIN, &C. 349 



white quartzitic sandstone and buff, fragmentary siliceous layers, which 

 latter rise high up in the surface of the hill, gradually flattening out in 

 their southwesterly inclination, and probably attaining a thickness of 

 several hundred feet. 



o. Clinking, fragmentary, thin-bedded, siliceous limestone, fieshy-grayj 

 weathers rusty reddish-gray, becoming very cherty below, and inter- 

 bedded with fine drab limestone. A heavy ledge in crest of ridge, dip- 

 ping 43° to 50°, S. 25° to 30° W. Small pentagonal discs of crinoidal 

 columns, in the chert, were the only fossils observed. 



p 1 . Immediately underlying the above bed occurs a ledge of dark gray, 

 brittle limestone, with a Zaphrentoid coral, Syringopam, Athyris subtil- 

 ita f This is followed by — v 



p 2 . Gray, gritty, hard, laminated limestone, which is in turn underlaid 



by— 



p 3 . Gray, cherty limestone, containing Productus longispinus^ P. semi- 

 reticulatus, &c. 



p*. Several beds of bluish-gray, spar-seamed limestone and cherty lime- 

 stone, with Syringoporcij crinoidal remains, &c, and cherty masses show- 

 ing a concentric structure. The latter beds appear in a bench in the 

 steep northerly slope between one and two hundred yards north of the 

 crest, and together with the overlying beds making up a heavy deposit, 

 dipping 45°, S. 20° W. The latter limestones are clearly Upper Carbon- 

 iferous, as shown by the presence of Productus longispinus and Athyris 

 subtllita. 



q. In slope below the above limestones, in the north side of the ridge, 

 reddish sandstone debris was observed, but no beds in situ. Elsewhere 

 similar ledges are interbedded with the limestones in this member of the 

 Carboniferous series. The slope below gradually merges into the basaltic 

 benches which surround these hills and incline gently in the direction 

 of the Blackfoot. 



As before intimated, the relation of this area to the Blackfoot Mount- 

 ains could not be traced for the intervention of the basaltic flow which 

 fills the intermediate depression. The strike of the strata is nearly the 

 same in both areas. In the latter, however, it is noticeable that the 

 beds have swerved round more to an east-southeast and west-northwest 

 course. The direction of the strike of these ledges extended northwest- 

 erly would intersect the equally disturbed belt in the vicinity of High- 

 am's Peak and Station IV, with which the present much disturbed belt 

 is probably synchronous. According to the confessedly meagre data 

 which were obtained at this place, there would appear to exist here two 

 sharp synclinals, separated by a narrow anticlinal fold, which is much 

 pinched and faulted on the south. In the space where this fault would 

 be looked for traces of trachytic debris were noticed, but not in quantity 

 sufficient to suggest this as having been a point of volcanic effusion. 

 The supposed fault indicates a downthrow to the south, probably double 

 the total thickness of the Jurassic, or 3,000 to 5,000 feet, and it may be 

 found to have intimate relationship with the complicated and probably 

 faulted Jurassic strata in the border of Lincoln Valley, just to the south 

 of Station IV ridge, with which the disturbed belt at the present locality 

 is thought to be intimately related. The interpretation here presented 

 of the structural features of the locality has been reproduced hi one of 

 the accompanying diagrams, representing a inofile section of the locality 

 above alluded to. 



WILLOW CREEK BASIN AND BASIN RIDGES. 



The southern central portion of the southwest section of the district is 

 occupied by an extensive basin-area, wlfich forms the low water-shed 



