8T.J0IIX.] SECTION — WILLOW CREEK BASIN, &C. 349 



white quartzitic sandstone and buff", fragmentary siliceons layers, wLich 

 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. 



0. Clinking, fragmentary, thin-bedded, siliceous limestone, fleshy-gray; 

 "weathers rusty reddish-gnxy, becoming very cherty below, and inter- 

 bedded with line drab limestone. A heavy ledge in crest of ridge, di])- 

 ping 4.30 to 50°, S. 25° to 30° W. Small pentagonal discs of crinoidal 

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



jj'. Immediately underlying the above bed occurs a ledge of dark gray, 

 brittle limestone, with a Zaphreutoid coral, iSyringojpora, Athyris aubtU- 

 ita f This is followed by — 



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

 by- 



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

 reticulatus, &c. 



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

 stone, with Sijringopora^ 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 4:5°, S. 20° W. The latter Umestones are clearly Upper Carbon- 

 iferous, as shown by the presence of Froductus lotigispinns 'djid Athyris 

 suhtilita. 



q. In slope below the above hmestones, 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 surroimd these hills and incline gently in the dii'ection 

 of the Blackfoot. 



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

 ams 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 

 coiu'se. The direction of the strike of these ledges extended northwest- 

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

 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 ui quantity 

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

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

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

 found to have intimate relationship with the comi)licated 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 intiniately related. The interpretation here presented 

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

 the accompanying diagrams, reijresenting a profile section of the locaUty 

 above alluded to. 



WILLOW CREEK BASIN AND BASIN EIDGES. 



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

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



