220 IRVING. 



divide to the southeast, no break in the continuity of the igneous 

 rock can be observed. The distinct southeastern outher, which 

 has ah-eady been mentioned, is completely made up of this rock, 

 but as we turn toward the southwest a small fragment of Car- 

 boniferous limestone is seen resting on top of the divide which 

 separates the forks of Raspberry gulch. Continuing the descent 

 of this divide, we encounter various exposures of Cambrian 

 shales. At a point six hundred feet lower in elevation than the 

 summit of the mountain, these dip at a low angle slightly to the 

 west of south. In the bed of Raspberry gulch, at the point 

 where its two forks unite is a thick sheet of igneous rock, over- 

 lain by Cambrian shales, which here dip sharply to the south- 

 west. 



The rock from this sheet was not examined microscopically 

 by the writer, and so cannot be said with certainty to be ident- 

 ical with that of Terry Peak. 



Again if we ascend the mountain from Foley flat, on the 

 ridge which separates the steep, amphitheatral basin from the 

 forks of Lost Camp creek we find not more than a few hundred 

 feet above the bed of the creek a ridge of unmetamorphosed 

 Cambrian shales dipping at an exceedingly steep angle to the 

 southwest. This is at a distance of nearly half a mile from the 

 igneous crest of the peak, however, and it is doubtful if that has 

 been the disturbing influence. Indeed, as we ascend still fur- 

 ther up the divide we may look off into the deep basin to the 

 south, and see the Cambrian in great development, but not in so 

 disturbed a condition. 



On the ridge which bounds this basin to the south the igneous 

 rock may be seen running further down toward the flat to the 

 southwest, than it does on the northern and western sides, but 

 still not attaining a thickness of more than three hundred feet 

 from the summit of the mountain. The southeastern side of 

 this ridge, which slopes off into Raspberry gulch was not ex- 

 amined, but from the way in which the igneous talus gives place 

 to sediments (as mentioned above) on this side it is probable that 

 the rock is not exposed there in much greater development. 

 On the northern and northeastern sides of the mountain the 



