ST. JOHN.] LOWER SNAKE RIVER VALLEY. 407 



large basin tract -svliich here occupies the valley. Along one of these 

 little caiionst, hrce miles above Fall Creek, interesting exposures of the 

 volcanics were met with, a section of which is reproduced in connec- 

 tion with the section-diagram of the mountain border north of Station 

 XXV, where their relations to the sedimentaries, as also the relative 

 position and succession of the somewhat variable elements of which 

 they are composed, are well shown. The section here referred to exhib- 

 its the various sheets of volcanic material rather rapidly rising from the 

 river bluffs iidand, where they reach an elevation of 800 to 1,000 feet 

 above the river-level. The inferior flows appear well up the canon in 

 the neighborhood of the sedimentary flank of the mountain, wlio.se foot 

 they bmy from view ; but the northerly inclination is apparently sufti- 

 ciently steep to carry these deposits beneath the river-level, tlie descent 

 being somewhere between 500 and GOO feet in a distance of perliaps one 

 and a half miles. The lowest member, «, shows an exposed thickness 

 of about 30 feet of dark drab trachyte. This is overlaid by h, dark, 

 vesicular, rudely bedded basaltic lava, 25 feet or more ; c, i)ink tiachyte, 

 or tuff, rather hard and weathered in slab-like fragments with a bedded 

 appearance, 30 feet or more ; d, conglomeritic deposit, made up of water- 

 worn pebbles of quartzite, limestone, &c., without distinct arrangement 

 in layers, held in a buff-drab matrix Hke a volcanic paste. This deposit 

 attains a thickness of 100 feet or more, forming picturesque mural bluffs 

 on the water side below the month of the gidch, and risuig inland, 

 southward, its debris scattered thickly over the surface of its outcrop 

 like accumulations of glacial drift. In the river bluffs and inland it 

 is overlaid by e, a volcanic ledge consisting of maroon-drab trach,si:e, 

 laminated gray trachyte or trachorheites, and intensely hard, dark, basal- 

 tic lavas, showing an exposed thickness of about 25 feet. The latter 

 flow extends high up on the foot of the mountain, occurring in sloping 

 plateau-like benches. The variety in the character of the components 

 of the volcanic deposits at this locality may not indicate so many dis- 

 tinct epochs of eruption and flow, the different materials apparently 

 having followed without cessation, in alternating order. Yet the pres- 

 ence of the interpolated conglomerate evidently shows an interval 

 between the earlier and later trachytic flows suflicient for the accumula- 

 tion of a heavy deposit of erratic materials which subsequent volcanic 

 action, by affecting its partial transformation, partly claims for its own. 

 This deposit, physically, bears intimate resemblance to that which 

 crowns the summit of Station XXIII in the northern part- of the Caribou 

 Eange, and AA'hich seems to form the basis of the volcanic rocks at that 

 place ; the chief differences noticeable being its inferior position and the 

 more distinct conglomeritic instead of brecciated character, from which 

 it may well be inferred the two deposits are not contemporaneous, 

 although, perhaps, similar in origin. 



Many beautiful views are gained from the trail passing over the high 

 benches, stretches of wide bottom plain, through which the gleaming river 

 winds in majestic curves, its siuface studded with beautiful islands and 

 the banks Ihied with tall cotton Avoods, here bordered by mural Islufts of 

 volcanic rock, fiinged with dark-foliaged pine and flr, and the whole 

 bounded by rugged mountain Avails, Avhich stretch aAvay in long lines of 

 perspectiA'e until lost in the distant windings of the valley. Certainly, 

 few locahties afford the same varied and none more beautiful scenery 

 than frequently greets the traveler in the lower valley of the Snake. 

 One of the prominent heights on the opposite side of tlie A-alley, about 

 midway between Fall Creek and Pyramid Creek, to Avhich Mr. IJechler 

 gave the name Promontory Peak, presents a singidar phenomenon in 



