340 EEPOET UNITED STATES GEOLOGICAL SUEVEY. 



7. Gray, spar-seamed limestone, appearing in tlie northeast face of tlie 

 mountain in successive low mural exposures. 



The vertical thickness of the beds exposed in Blackfoot Peak is diffi- 

 cult to estimate with a degree approaching nearer than a rough approx- 

 imation; but it probably amounts to above 2,000 feet, including the 

 upper siliceous horizons of the Carboniferous, but not showing the super- 

 imposed "red-beds," or Trias, but which, it is believed, may exist between 

 the two main ridges of the range at this locality. The connection of the 

 beds occurring in this eastern ridge with the Carboniferous ledges which 

 make up the west or Wolverine ridge was not actually traced, the inter- 

 vening space in the upper basin of Wolverine Creek showing no out- 

 cropping ledges trom beneath the detrital materials which compose its 

 rounded, grassy slopes ; but it seems highly probable that the beds com- 

 posing the latter ridge occupy a lower stratigrai)hic position than the 

 crest-ledges in Blackfoot Peak, and to account for their jjresent relative 

 position it seems within reason to infer either the existence of a line of 

 dislocation of the strata, or, x)erhai:)s, a fold, the axis of which lies within 

 the area included in the depression of the upper basin of the Wolverine. 

 The latter supposition is hinted in the section across the range along the 

 course of the Wolverine, given in an accompanying diagram, and it would 

 appear to be the more plausible of the two inferences in explanation of 

 the stratigraphic relations of the east and west ridges. 



The view from Blackfoot Peak, which is rather conspicuous from its 

 isolation than on account of its relative height, is both extensive and 

 very fine. Although our first view of the Tetons was had from Mount 

 Putnam, nearly 30 miles to the south westward, from the i3resent mount- 

 ain the first objects that arrest the attention are the great obelisks 

 which dominate our district and which rise up grandly away to the 

 northeastward 60 miles distant, their pedestal of mountain plateau, at 

 this season of early summer, showing nearly an unbroken field of snow, 

 above which the bare rocky cones spring to heights 12,000 to near 14,000 

 feet above the sea. Intervening, the lower range of the Snake Eiver 

 Mountains hides the great foreland slopes of the Teton Eange, and nearer 

 still a belt of wild, broken hills, and a broad basin-depression with 

 isolated low ridges, mark the position of the Caribou Eange and Willow 

 Creek basin, which occupy the country between the Snake Eiver Eange 

 and the Backfoot Mountains. The northern termini of all these mount- 

 ain and hill ranges present the volcanics gently upraised in successive 

 benches, which sweep down in graceful curves into the great x)lain of 

 the Snake, the same on the Blackfoot Mountains as on the Caribou and 

 Snake Eiver Eanges and the lesser ridges in the foreground. To the 

 south the wooded ridges of the southern continuation of the main ridge 

 of the Blackfoot Eange shut out the view and a clearer exhibition of 

 the geological features alike. 



In the foreground just to the east of Blackfoot Peak occurs a narrow belt 

 of low ridges, in whose southwest slojies obscure outcrops of soft yellow- 

 buff deposits interlaminated with harder layers, occur, overlaid by varie- 

 gated i)ale-reddish clays in bands, dipping oft" to the northeast at a mod- 

 erate angle of inclination, and making up a thickness of several hundred 

 feet. In the absence of fossils it may be a matter of conjecture in assign- 

 ing these deposits to their proper place in the geological scale, while their 

 relations to the Carboniferous beds in the monoclinal ridge from whose 

 foot they incline is enveloped in some uncertainty from the same cause. 

 They are believed to be the equivalent of certain deposits, possibly rep- 

 resenting early Tertiary or Laramie Group beds ; but their ];)osition in 

 relation to the well-determined age of the beds in the mountain crest is 



