st. jomf.] LOWER VALLEY OF SNAKE RIVER. 405 



placers derived their gold is situated in Mount Caribou. At the time 

 of our visit I was fortunate to meet one of the partners of an enterprise 

 looking to the development of the parent lodes. Messrs. Griffin & 

 Xoelans have begun a shaft upon a lode which outcrops high up on the 

 southerly declivity of the peak a mile to the southeast of Station 

 XXVIII. The lode has a strike about X. X.W. and S. S.E., nearly ver- 

 tical, or inclined southerly, if at all, and seems to be very wide ; indeed, 

 no well-defined walls have as yet been discovered, the exploration hav- 

 ing been carried to a depth of about 60 feet by an excavation 8 feet in 

 diameter. It is composed of rotten ferruginous quartz inclosed in the 

 peculiar tough trachytic mass, its relations apparently being that of a 

 dike or true vein, which may also traverse alike the sedimentaries and 

 eruptive materials. Xo assay of the lode-rock had been made from which 

 even an approximate knowledge of its value might be gained ; but a 

 little gold has been extracted by the rather crude processes at command 

 of the explorers. I believe there are other " discoveries" of similar char- 

 acter in the neighborhood, but none developed to the same extent as 

 that above noticed. In the vicinity of the Griffin lode, some 300 yards 

 to the southwest, a vein of magnetic iron ore has been discovered in the 

 hornblendic trachyte mass which forms the bulk of the western side of 

 the mountain. This vein, from which specimens were obtained, is said 

 to be 20 feet wide, and extends in a northwest and southeast direction, 

 or nearly parallel with the above-mentioned auriferous lode. 



LOWER VALLEY OF SNAKE RIVER. 



That portion of the course of Snake Eiver below the grand canon 

 traverses a typical valley trough defined on either hand by mountain 

 barriers, to which we have applied the term lower valley of the Snake. 

 This valley, with its southern continuation in Salt Eiver Valley, has a 

 northerly and northwest course of about fifty miles within the district, 

 and an average width between*the crests of the opposing mountain ridges 

 of eight to ten miles. To the northwest it opens out into a wide recess 

 communicating with the Snake plains, the barrier ridge of the Snake 

 Eiver Mountains throwing out a long low spur along the northwest 

 border considerably beyond the terminus of the Caribou Eange on the 

 southwest side of the valley. The often-mentioned volcanic upland 

 bordering the Snake plains sweeps round the extremities of the above 

 ranges, filling the broad debouchure and extending up the valley half 

 the distance to the grand canon, forming a continuous sheet of A^olcanic 

 materials with that which fills the Willow Creek Basin to the south and 

 similar recesses to the north. 



A few miles below Fall Creek, at the point where the river makes a 

 bend to the north, it begins its canoned course in the basaltic rocks, 

 which thence confine the river in a narrow channel between precipitous 

 walls of dark lava, until it emerges into the level plain, 15 to 20 miles 

 below. Above this lower canon pretty little alluvial expansions border 

 the stream, at intervals interrupted by high, jutting benches of the vol- 

 canic rocks, until just above Fall Creek the stream opens into a consid- 

 erable basin area, floored with Quaternary gravels which are fashioned 

 into low terraces. This prairie bottom extends a distance of 6 to 8 miles 

 up the valley, mainly lying along the opposite side, the stream skirting 

 the foot of the volcanic bench on the southwest side, with here and there 

 narrow intervale tracts intervening. Approaching Pyramid Creek the 

 volcanics again converge from either side, forming the narrows through 

 which the stream winds amidst varied, picturesque scenery a distance 



