6T.J0HN.] PALEOZOIC AREAS — UPPER CARBONIFEROUS. 489 



types, as understood at the present time. Indeed, these njiper beds re- 

 call the Saint Louis formation from the abundant prevalence of the coral 

 Llthostrotion in them. These distinctively red passage beds are succeeded 

 by a heavy series of reddish-tinged buff, fragmentary, siliceous deposits 

 and limestones, which bridge over the Teton Pass and the mountain side 

 to the west, and are finally succeeded by the Triassic " red-beds" within 

 the disturbed belt of the Snake River Eange to the southwest. The 

 Gros Ventre Mountains and Buffiilo Fork Teak show much the same 

 materials in tliis horizon, so far as time permitted of ascertainment. To 

 the west and southwest, however, this particular horizon was not recog- 

 nized, if it there exists. 



The principal stratigraphical peculiarities of the Upper Carboniferous 

 series, exclusive of the extreme upper or Permo-Carboniferous horizons, 

 consist of alternations of heavy beds of brittle, buff, siliceous material, 

 or buft', reddish-tinged, laminated sandstones, usually quartzitic, gray to 

 drab, siliceous or cherty, sometimes spar-seamed limestones, and vari- 

 egated shales, which may reach a thickness of from 1,000 to 2,000 feet. 

 The siliceous deposits predominate, but, owing to their fragmentary 

 nature, their outcrop is usually strewn with the tine, angular debris de- 

 rived from the breaking up of their own beds, except where the ledges 

 are steeply tilted, when they are weathered into exceedingly craggy crests 

 or hog-back ridges. These siliceous beds have afforded no fossils, ex- 

 cept fucoidal-like markings. The limestones, however, afford fossils, 

 which, as has been pointed out in preceding pages, x)resent Upi)er Car- 

 boniferous facies. 



In the Blaclvfoot Eange these deposits show a thickness probably as 

 great as that of the inferior limestones. Its limestone layers contain, 

 amongst a grouj) of fossils which, in the i)resent state of knowledge, 

 might not be regarded as of great value in the definition of epochal forma- 

 tions, a few forms that are regarded as characteristic of the Uitper Car- 

 boniferous or Coal-Measure period. Sucli are the Atliyris subtilita and 

 Froductus longispimis, yxhiGh. are associated yi-ith Productus semireticu- 

 latus (?) Hemipronites, minute crinoidal columns, Zaphrentoid corals, and 

 a delicate form of Syringopora. On the northeast flank of the Caribou 

 Eange, limestones which hold apparently the same relative i^osition are 

 crowded with crinoidal columns, Ptilodictya, Fcncstclla, Spirifer, Pro- 

 ductitSj and a small Platyceras uudistinguishable from a form, originally 

 described bj^ Mr. Meek, from the Upper Coal Measures of Nebraska, and 

 which has subsequently been identified by Dr. White in collections from 

 Carboniferous rocks near Santa Fe. 



East of the Mount Putnam ridge the sedimentary strata form a shal- 

 low synclinal, in the eastern border of wliicli occurs a heavy series of 

 siliceous beds and quartzitic sandstones, interbedded with bands of lime- 

 stone, which, although not with certainty identified with the Upi^er Car- 

 boniferous, hold a position inferior to the Jurassic deposits, which latter 

 occur in the low ridge along the axis of the synclinal. It is jiossible 

 that these ui)i)er siliceous horizons include Permian or Permo-Carbon- 

 iferous beds. But to the north, in the continuation of the same ridge at 

 Station V, Higham's Peak, the jiartially magnesian limestone layers 

 associated with the siliceous deposits, which latter are here tilted into 

 vertical position, traces of an interesting fossil fauna were observed, 

 consisting of 3Iyalina, Aviculoj)ecten, S2)infcr, and crinoidal remanis, 

 which certainly recall the fauna! phases of high Upjier Coal-^Measure de- 

 l)0sits in the country bordering the Lower Missouri in Iowa, Kansas, and 

 Nebraska. But at this locality the strata are in so disturbed a condition 

 as to render their satisfactory study an undertaking of some difliculty. 



