sT.Jonn.l SECTION THROUGH STATION XXVI RIDGE. 385 



Station XXV pertain to horizons included in the Jurassic, the resem- 

 blance of which to the Trias "red beds" is very marked and liable to 

 deceive. It is not improbable the lower ledge of hmestone arches over 

 an anticlinal fold the axis of which lies a little to the northeast of the 

 exposure in the space at present overflowed by the volcanic rocks. But 

 the data are insufficient to more than suggest such a state of things. 



Opposite Station XXV the Snake Valley changes its course, curving 

 round due southeast, ascending, which direction it holds to the conflu- 

 ence of Pyramid Creek, and between those points the volcanic flows 

 reach up on the foot of the range several hundred feet above the river- 

 level. In connection with then general southeasterly strike, the bend 

 of the valley brings the "red-bed" series to thefront of the range before 

 reaching the Pyramid, where they dip into the mountain, southerly. The 

 Pyramid is a high conical trachytic hill, outlying the mountain-side, and 

 standing almost isolated in the valley, which is here contracted and filled 

 with low hills for a few miles intervening between the lower and ui^per 

 basins. Pyramid Creek debouches into a basin area, hemmed on the 

 •west by the steep red sandstone hills, and on the opposite side by the 

 continuation of the same deposits and an outlying tongue of low wooded 

 hills which projects from the foot of the mountain nearly to the river-sido 

 above a mile distant to the northeast. Looking up the canon, which 

 begins about three miles above the mouth of the creek, red beds alone 

 form the conspicuous strata discernible. But in making the ascent of 

 the main front ridge of the mountain, on the height of which Station 

 XXVI was established, members of other important formations are met 

 with, and on gaining the summit we have also mounted in the geological 

 scale to the horizon of the Jurassic. The section follows a course from 

 the Snake Valley west of south a distance of four or five miles, and al- 

 though over wide belts in the lower slopes, few details are revealed, due,, 

 probablj^, in i)art at least, to the position of the strata, and i^artly to the 

 wooded condition of the slopes, the upper horizons afforded an interest- 

 ing and better exposed set of deposits for study. 



Section through Station XXVI ridge. 



1. Dark red rock debris, appearing here and there in wooded ridge^ 

 close by the margin of the river. 



2. Gray and drab limestones, obscure. 



3. Gray, flesh-tinted quartzite conglomerate, bedding very hidistinct, 

 at one place inclining W. 15° S. at an angle of 40°. It forms a heavy 

 ledge outcropping in the crest of the low ridge on the northeast side of 

 the trail saddle, connecting this outlying group of low hills with the 

 mountain. In other places the ledge seems to dip northeastward, at a 

 less steep angle of inclination, and again it dips west at an angle of 48°; 

 but the first mentioned observation is probably nearer correct. 



4. Hard, spar-seamed, bluish limestone, bedding almost or quite obso- 

 lete, but appearing as a heavy ledge plating the southwest slope descend- 

 ing into the saddle depression. 



5. Obscure traces of red shales, staining the soil red in the saddle 

 (over which the trail passes leading up this side of the valley), and reach- 

 ing up on the mountain foot. Bluish brecciated limestone fragments arQ 

 scattered over the siuface. 



0. In a break in the wooded slope, 500 to 800 yards alcove the trail 

 saddle, debris of gray spar-seamed limestone appears, indicating th© 

 presence of a heavy subjacent ledge. 



7. A few himdred yards above the last, an obscure ledge of hard red 

 25 G s 



