BT.jonx.] TETOX PASS MOUNTAINS. 435 



to in connection with the notice of the southern extremity of the T6ton 

 Eange. These deposits doubtless here' recline on the flank of the great 

 range, dipping southerly conformably with the Carboniferous deposits 

 which rise up into the high dominating peaks at this end of the range. 

 As there mentioned, theVolcanics fringe the foot-hills weU uj) into the 

 little valley, on the southwest side of which, however, they were not rec- 

 ognized. It was a notable fact that the foot-hills of the S6ton Pass and 

 Pierre's Mountains below Station XXXIX were quite denuded of the 

 latter class of rocks, which on that side of Pierre's Basin do not reappear 

 until we have passed to the north of Spring Point, where they again exhibit 

 characteristic upraised benches resting on the border foot-hills. Passing 

 up Teton Pass the way gTadually penetrates alike deeper into the range 

 and lower in the geologic series, so that, at a point two to four miles 

 from the summit of thepass the Carboniferous ledges heavily plate the 

 immediate mountain slope. There the diminished brook again turns 

 southeast and soon passes into the horizon of the "red beds," which 

 continue to the high saddle next west of the summit, where they display 

 characteristic exiiosiu-es of deep red sandstone and arenaceous softer 

 beds, dipping southward at an angle of 45°. From the latter point the 

 trail again passes north of the trend of the "red beds," the way passing 

 over steep slopes buried beneath vast accumulations of intensely hard, 

 fragmentary, buff, and reddish silicious rock, which was found to be 

 heavily developed and comi)osing a zone of low elevations immediately 

 south of the siunmit. The relative position of the latter silicious horizon 

 is weU discerned from the mountain which rises immediately north of the 

 pass, Station XLIII. 



From the latter mountain summit the view embraces the whole coun- 

 try, sweeping round from the east, south, into the west, and commanding 

 nearly the whole of the highland region crowded into the great southern 

 bend of the Snake Eiver. In the immediate neighborhood of the Teton 

 Pass the silicious deposits of the upper measures of the Carboniferous 

 form a belt of low hills, in whose steep declivities bands of the included 

 red, gritty shales simulate the "red beds" of the Trias, only much less 

 considerable in vertical extent. But just beyond, in the slopes descend- 

 ing from higher ridges, appear here and there extensive open tracts whose 

 cover of luxuriant herbage we had come to associate with the presence 

 of ]ieculiar geological deposits ; and we have the confirmation of the 

 su]>position in numerous slides in the steeper slopes, which reveal ex- 

 tensive exposures of the Triassic " red beds." These deposits are easily 

 traced in a wide belt having a general west-northwest and east-southeast 

 trend, in the former direction passing down into the lower course of West 

 Teuton Pass Valley, and in the latter extending into the foot-hills south 

 of East Pass Creek, where they are hidden from sight by the forests 

 which very generally cover the hills in that quarter. Still beyond, south- 

 west, the ridges show quite extensive exposures of buff and grayish 

 deposits, to the southwest of which another belt of "red beds" intervenes 

 between the last and the immense accumulation of hght-drab strata 

 dimly seen in the escarpments of the prominent mountain heights which 

 rise immediately from the eastern border of the lower valley of the Snake. 

 This is, in brief, what appears from the commanduig summits north of 

 the pass. The distance is too great, to say nothing of the great extent 

 of surface clothed in forests and other growths in which tlie subjacent 

 strata are concealed from -s-iew to render it possible to gain more than 

 the barest general outlines of the distribution of the geological forma- 

 tions, not even the inclination of the strata being satisfactorily revealed 

 in the middle and more distant ridges ; while, of course, all stratigraphic 



