st. join?.] KEGION OF STATION XXII. 375 



of the mountain a tMck ledge of hard, darkish gray, laminated sandstone 

 is exposed in a low wall which sweeps down into the deep gulch iu the 

 direction of the exposure of bed No. 55 of the preceding section, with 

 which it is either identical or but little removed to the north. The dip 

 of the bed here is north-northeastward at an angle of 45°. In the oppo- 

 site direction the same narrow comb is still traced in the flank of the 

 ridge towards Station XXII, the trend curving gently round into a 

 course south of west. In a lower eminence of the ridge, west of the 

 trachyte dome, occurs a heavy bed of hard, reddish-gray, laminated 

 sandstone, in thin layers, very like that last-mentioned above, and dip- 

 ping at an angle of 10°, X. 10° W., though variable, as though it formed 

 part of the undulating arch of a low dome or fold. It is here overlaid 

 by a ledge probably the same as that in the trachytic dome, which out- 

 crops in the north flank 300 yards below the crest. To show the vari- 

 able lay of these strata, even within short distances, at one point in the 

 west end of this eminence the bed dips westward at an angle of 20°, and 

 in the low connecting ridge just beyond the dip is to the X. 5° W., at 

 an angle of 30°. These beds are apparently underlaid by a ledge of 

 dirty brown, minutely brecciated or conglomeritic gritty limestone, upon 

 which rests a gray sandstone ; and in the summit of the high point half 

 a mile east of XXII, there appears a still higher heavy ledge of gray, 

 reddish-tinged, laminated sandstone, changed almost to the condition 

 of quartzite, dipping 40°, X. 15° W. The latter may belong to one of 

 the previously mentioned ledges. 



Passing from the last-mentioned point to Station XXII, the summit 

 of the mountain is found to be capped by a much broken up exposure 

 of flesh-tinted, gray, intensely hard sandstone, dipping northwestward. 

 In the southeast declivity, about 200 feet below the summit, the descent 

 is broken by a low mural exposure, which forms so conspicuous a feat- 

 ure in the mountain-side as seen from Station XXI. This wall shows 

 a thickness of 15 feet or more of very hard, laminated, gray, reddish- 

 tinted sandstone, almost a quartzite, which, at the point examined, dips 

 15° to 20°, X. 5° E. In a less marked bench intervening between the 

 above and the summit, a heavy ledge of thin-bedded, gray sandstone 

 outcrops, with a dip of 40°, X. 45° E. The lower ledge is, as.previously 

 observed, identical either with that forming the crest of Station XXI or 

 the next ledge to the south, the bed and associated strata at the present 

 locality apparently holding an inverted position. 



The above somewhat disconnected observations are introduced with 

 the view of presenting all the leading data possessed that may aid to a 

 fan elucidation of the complicated structural features pertaining to the 

 west flank of the northern portion of the range. It would appear that, 

 in this northern country, phenomena of the kind here mentioned are by 

 no means of rare occurrence : but in the present instance, to the writer 

 at least, they were of so great interest, and in spite of our opportunities, 

 or their lack, not quite worked out to our perfect satisfaction, that it 

 was deemed preferable to give a summary of the detail examinations on 

 which the conclusions arrived at were based, that they may be shown to 

 be consistent with the facts so far as observed. 



Station XXII occupies a commanding position on the western verge 

 of the range at the head of Smoke Creek (east fork of Willow Creek), 

 immediately overlooking the west-sloping volcanic plateau which termi- 

 nates in a line of steep, high bluffs, fronting the station on the west and 

 northwest, and which were once continuous with the similar benches 

 either side of Porcupine Creek. These volcanics, as at the latter local- 

 ity, gently slope to the level of the volcanic-floored upland bordering the 



