452 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



more intense manifestation or local concentration of the same elevatory 

 forces. 



Mention was made of the great spur to the west of Station XLIV, 

 whose abrupt terminus fronts the eastern escarpments of the Lower 

 Gros Ventre Buttes. This ridge is seen to be heavily burdened by the 

 older sedimentaries which occupy a shallow sag between the above- 

 mentioned saddle and its high western point, which latter appears to be 

 partially flagged with quartzite, and corresponds to the sharp fold 

 noted in making the ascent of the foreland ridge north of this spur. 

 Hence, it would seem very probable that we have here another and 

 parallel uplift which culminated in the great spur, to the northwest of 

 which it is far less conspicuous, and may gradually diminish and finally 

 die out; in the opposite direction its character could not be clearly ascer- 

 tained. All these folds have a general parallel arrangement, trending 

 about southeast and northwest, approximate. 



Along the northern or northeastern border of the range, there appear 

 the edges of great blocks of tilted strata, showing the gray of the Car- 

 boniferous limestones, and the peculiar colors of the "red bed" series, 

 the disposition of which is exactly that of their occurrence in the north- 

 east flank of the Wind River Range, whose snow covered domes just 

 rise to view far away to the south of east. Southeastward of the high 

 Archaean peak, the main crest of the range, or such it appears to be, 

 along the southern border, is soon surmounted by the sedimentaries, 

 quartzite, and Quebec Group limestones, which dip gently northeastward 

 into the depression at the foot of the great northern fold. The southern 

 flank of this crest was at no point visible, so that we do not know 

 whether it presents an abrupt pitch of the strata similar to the corre- 

 sponding flank of the northern fold, or the beds more gradually descend 

 into the basins at the heads of Hobacks and Green Rivers, in which 

 latter, to the eastward, in the neighborhood of Union Pass, Dr. Hayden 

 found extensive developments of the Tertiaries rising high up on the 

 western flank of the Wind River Mountains. 



To the south-southeast the view embraces avast extent of haze-obscured 

 country, devoid of prominent orographic features, and which evidently 

 belongs to the Green River Basin. To the south and south-southwest 

 massive mountain ridges define the horizon, their summits showing large 

 patches of snow, and which form the southern extension of the Snake 

 River Range between Hoback's and Salt Rivers. From the eastern 

 border of this mountain belt a dark, even-crested, gradually diminishing 

 ridge extends far out into the above-mentioned basin region. It resem- 

 bles the great volcanic plateau slopes north of the Teton Range, but 

 Dr. Peale, in whose district it lies, found it to be made up of Green River 

 and Wasatch Tertiary. The Snake River enters the Grand Canon to the 

 south-southwest, and is soon lost amidst a labyrinth of deep gorges and 

 rough mountainous country. Southeast or east of the upper entrance 

 the Grand Canon a rather low but very broken group of mountains, 

 traversed by rugged gorges tributary to the Snake, seems to be entirely 

 composed of deep red strata, disposed in broad belts, beyond which are 

 seen grayish deposits in the main mountain crests, which are probably 

 Carboniferous limestones, upon which the red beds rest. The latter are 

 the deposits mentioned by Professor Bradley as forming three well-de- 

 fined anticlinal folds in the upper third of the Grand Cauon below the 

 mouth of Hoback's River. The trend of these anticlinals is, however, more 

 to the south than that of the Gros Ventre folds, giving rise to the narrow 

 triangular area which separates the latter from the Snake River Range. 

 In the belt belonging to the southern or southwestern flank of the Gros 



