NOBLES PASS, 49 
which descends in a broken, rocky ravine; and in its lower portion its walls frequently become 
vertical for considerable distances, partaking exclusively of the cañon character. Seven miles 
above the valley it is entered by a large ravine from the southeast, but it still preserves its 
general course, and eventually runs out. It is frequently broken throughout its entire length 
by small side ravines, and is generally narrow at the bottom and broad at the top ; but, for 
short distances, it is aMekésntely broad and narrow at the top and bottom. For the first dines 
or four miles above the valley, the ravine is from two hundred to two hundred and fifty feet 
deep, but above that it seldom exceeds forty feet, except where small ridges, or spurs, approach 
it, when its walls become much higher, but are less vertical. After ascending it for eight 
miles, we crossed it, and ascended an ladies peak near it. The position of this peak was 
favorable for pbuorvation; but we could nowhere discover a route superior, or at all equal, to 
the one we were flowin, for a railroad to ascend this pass. Continuing our examination; 
therefore, we ascended the stream for four miles on its southern bank, to where it again 
receives a considerable branch from the southwest, and two small ones fiin the opposite side. 
But it was here rapidly running out; and a short distance above, the main stream descends 
in à channel but slightly depressed below the surface of the broad mountain plain which we 
were approaching. Passing again to the north side of the stream, we ascended it a short dis- 
tance, and then crossed over and encamped with the main party, which had followed the road, 
on Summit creek, at our former camp of July 2. 
July 9.—In leaving camp this morning, I followed the open, grassy plain, lying between 
Summit and Pine creeks, while Mr. Egloffstein proceeded with a party down the former stream 
until it disappeared in the plain; and then crossed over, without any material change of level, 
to the head of Susan river; and thence continued our line of yesterday, from Susan river by 
the ascending plain to Pine creek. This portion of the mountain is unobstructed by any 
sudden rise or fall, and can be traversed for several miles in any desired direction without 
obstruction. It will require a minute survey of the lower portion of this pass, to determine 
the best line by which to effect its ascent by a railroad ; whether by ascending the ravine of 
the river, by which the grade is comparatively small, or by rising as soon as possible to the 
top of the ravine, with a heavier grade, thereby avoiding, to a considerable extent, the expensive 
labor of removing rocks for its passage. It is believed to be practicable to accomplish either. 
The ascending grades by the river, from Roop’s farm, are, for the first four miles, an average 
of 10.10 feet to the mile; and for the next four miles, 105.50 feet to the mile; then 59.10 feet 
to the mile for 4.50 miles; and for the next 7.25 miles, after leaving Susan river, 75.10 feet 
to the mile; followed by 31.10 feet to the mile for 7.25 miles, and 54.30 feet per mile for 
2.95 miles; with a descending grade of 27.70 feet per mile for five miles, to the west side of 
Pine creek. From Pine creek we passed through the open pine woods, and, bearing to the left, 
followed a grassy plain, gradually descending for 4.73 miles, with a high ridge on our left, 
which we continued to pass around, changing our course more to the south as we progressed. 
This prairie was from one to three miles wide, and was marshy in the southwestern part, where 
it terminates. Leaving it, we again entered a heavily timbered district, descending consider- 
ably for 3.75 miles, when we came again into an open prairie, and encamped on Black Butte 
creek—a small stream, three feet wide, flowing a little to the west of north, and eventually 
disappearing in the dee The characteristic feature of the country Mini to-day is the 
broad trunk of the mountain—the plains which we are following—surmounted by elevated 
peaks and ridges, having no uniform direction, and with elevations varying from five hundred 
to three thousand feet above the plains, with drifts of snow only upon the most elevated peaks. 
From west of Pine creek to this camp the average natural grades, given by our barometers, 
are, for the first 2.89 miles, a descent of 63.20 feet to the mile; and 19.50 feet per mile bor 
the following 1.84 miles ; and 71.90 feet per mile for the next 1.70 miles; and 64.90 feet per 
mile for 2.05 miles; and 113 feet per mile for 1.55 miles thence to camp, where our altitude is 
5,084 feet above the sea. 
Tb 
