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taneous observations at the West Butte, was 6,673 feet.* Lieutenant 
Blackiston, in 1858, made the height 6,030 feet, by a single observation 
in unsettled weather. The trail descends on the west side of the water- 
shed ridge very rapidly, and at the distance of three quarters of a mile, 
crosses a little brook which lies 1,325 feet lower than its summit, and 300 
feet below the stream last crossed on the east side. It next passes for 
about two miles along the face of a very steep hill-side, when a descent is 
again made to a piece of flat ground in the bottom of the valley, covered 
with a scattered erowth of young pines. (P. contorta, var. latifolia Eng.) 
This place may be called the West Fork, as a second valley as large as 
that of the pass, here comes in from the south-east. The rocks in the hill- 
side last mentioned, dip generally north-westward ; they appear to belong 
to the same series as those of the watershed ridge, and to be included, — 
at least for the most part,—in division C. The lower part of the hill is 
composed principally of greenish slaty-rocks and sandstones, while at the 
higher levels, red sandstones preponderate, and are seen to be overlaid 
just north of the West Fork, by a remnant of the great limestone D. 
133. Westward from the West Fork, the Valley of the Pass was 
examined for about four miles. It is here hemmed in by two immense 
mountain masses, which were at once recognised as Mts. Yarrell, and 
Kirby and Spence, of Lieut. Blackiston. ‘The rocks in these havea 
general easterly and north-easterly dip, and appear to be unconnected 
with those of the central region last described, and probably separated 
from them by a fault. About a mile from the Forks, in the north side of 
the Pass—which as before offers the best section—a great series of 
reddish sandstones, often in quite massive layers, is found. The tint is 
most pronounced in the upper layers, the lower becoming interstratified 
with thin beds of yellow-weathering magnesian limestone, often con- 
cretionary, which finally preponderate in giving colour to the strata. 
These rocks represent Series F. and G., elsewhere more fully noticed. 
Below them, and forming a prominent feature, is the trap bed EK. It 
retains its character as before described, but in Mt. Yarrell, is much more 
important, and must be at least 100 feet in thickness. The great 
limestone D., is here also shown, underlying the trap; and is well situated 
for examination, as the whole of the beds come down in succession on the 
trail. It is not so highly magnesian as the limestone B., and generally 

*The observations were as follows:—Aug. 15th, 11,25 A.M., 6,682; Aug. 16th, 11.20 A.M., 6,678; Aug. 
20th, 10.20 A.M., 6,659. 

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