st. John-.] CAEIBOU RANGE. 363 



bedding', associated with red shales, which stand in various positions, or 

 dipping from vertical at one point G5°, X. 45° E., changing in a short 

 distance to the opposite direction at a steeper inclination. This con- 

 tinues to be the character of the ridge to its northwest extremity, where 

 it is broken down in a low saddle at the head of Mosquito Gulch, which 

 connects it with the highlands to the northwest on which Station XIX 

 was located, about three miles distant from Station XVIII. At the lat- 

 ter point the ridge shows an interesting section. The last-mentioned 

 sandstone horizon, forming a brown weathered ledge with red shales, 

 outcrops in the south declivity a hundred yards from the summit, and 

 dips steeply southward. A little higher in the ' slope, a heavy ledge of 

 (12) bluish-drab, spar-seamed limestone forms a break in the steep de- 

 scent, the dip ranging from 45° to 60°, S. 30° to 40° W. It contains 

 numbers of a small Gastreopod and very imperfect Lamellibranchiates, 

 and vertebrate remains. Of the latter, only a few indeterminable frag- 

 ments of bone, and a single specimen of a vertebra, rewarded a careful 

 search. The Gasteropods are undistinguishable from a form occurring 

 elsewhere in post-Jurassic deposits, and the Lamellibranch may prove 

 to belong to the genus TJnio. Professor Cope's determination of the croc- 

 odilian affinities of the vertebra also bears strong, though not conclusive^ 

 evidence in favor of the transitional or early Cenozoic age of these de- 

 posits. The Limestone is immediately succeeded by (13) indurated brown- 

 ish ferruginous deposits, also containing obscure fossils, apparently a 

 LameUibranchiate shell. The crest of the ridge immediately above the 

 latter exposure is formed by a heavy bed of (14) hard, grayish blue, 

 rusty weathered, spar-seamed, brecciated sandstone, with slickenside 

 surfaces, and much broken up. It clips 75°, S. 30° W., in places verti- 

 cal. 



From the foregoing observations it is apparent that we at the outset 

 of our examinations along the outlying southwestern border of the range 

 encounter evidences of the extraordinary character of the disturbances 

 which constitute so prominent a feature in its dynamical geology. In 

 the short space gone over there are two sharp folds, that on the crest of 

 which Station XVIII is located, pitching steeply to the northeastward, 

 and in places thrown beyond the vertical, reversing the order of super- 

 position of the strata involved in the overturn. The northeast face of 

 Station XVIII ridge falls rapidly into the gulch of the main northwest 

 branch of the East Fork, over a declivity covered with dense thickets 

 and coniferous forests. Beyond lies a far more broken and higher mount- 

 ain region, culminating in Station XXV, 10 miles to the northeast, which 

 overlooks the lower valley of the Snake between Pyramid and Fall 

 Creeks. To the north, this ridge attaches to the water-shed at Station 

 XIX, northwest of which it sinks into a broad depression some six miles 

 across and 800 feet in depth, opening a low pass from Willow Creek, via 

 Fall Creek, across to the lower valley of the Snake. This pass is very 

 like the depression at the head of McCoy Creek, though the canoned 

 course of Fall Creek affords a less practicable route for a highway than 

 the more open valley of the former stream. The view looking south and 

 southeast embraces the basin ridges west of Gray's Lake, and the crater- 

 like northwestern face of Mount Caribou, and far in the distance, in the 

 direction of the Wind Eiver Mountains, a line of snowy peaks stretches 

 across the horizon. 



Approaching Station XLX from the valley of Willow Creek, a section 

 is crossed which extends our knowledge of the component strata in a 

 belt still more northerly than that just noticed. The way leads in a gen- 

 eral northerly course a distance of about six miles, the southern third or 



