14 ROUTE NEAR THD FORTY-FIRST AND FORTY-SECOND PARALLELS. 
suitable for settlement and cultivation. Immediately west of Great Salt lake there is a plain 
of mud, clay, and sand, impregnated with salt, seventy miles in width from east to west by 
its longest line, and forty at a narrower part further south, thirty miles of which must be piled 
for the passage of a railroad across it. A railroad may be carried over this series of valleys and 
around the mountain masses, at nearly the general level of the valleys. 
The route in this manner reaches the foot of the Humboldt mountains, a narrow but elevated 
ridge, containing much snow during most of the year, and crosses them by a pass nine miles 
long, about three of which are occupied by a narrow, rocky ravine, above which the road should 
be carried on the sloping spurs of the mountains on the western descent; elevation of summit 
6,579 feet above the sea. At the time when passed, 21st May, snow covered the high peaks 
above it, and a few drifts extended into the ravines down to the level of its summit. 
The descent is now made to the open valley of Humboldt river, which is followed for about 
190 miles. The steepest grade proposed in the pass of Humboldt mountain is 89 feet per mile 
for eight miles, but this can be reduced by gaining distance to any desirable extent. 
The Humboldt river, as described by Colonel Fremont, is formed by two streams rising in 
mountains west of the Great Salt lake. Its general direction is from east to west, coursing 
among broken ranges of mountains; its length about three hundred miles. It is without 
affluents, and terminates near the foot of the Sierra Nevada in a marshy lake. It has a 
moderate current—is from two to six feet deep in the dry season, and probably not fordable 
anywhere below the junction of the two streams during the melting of the snows. The valley 
varies in width from a few miles to twenty, and, excepting the immediate river-banks, is a dry, 
sandy plain, without grass, wood, or arable soil. Its own immediate valley (bottom) is a rich 
alluvion, covered with blue grass, herds-grass, clover, and other nutritious grasses, and its 
course is marked through the plain by a line of willow. 
Of the three lines from the Humboldt river to the foot of the Sierra Nevada, the best is that 
by the Noble’s Pass road, as it avoids the principal range of mountains crossed on the line 
followed a few miles south. The line followed crosses two ranges of the general character of the 
Basin mountains, and reaches the foot of the Madelin Pass of the Sierra Nevada, on the west 
shore of Mud lake, in a distance of 119 miles, and at an elevation of 4,079 feet above the sea. 
In this latitude the Sierra Nevada was found to be a plateau about 5,200 feet above the sea, 
40 miles in width from east to west, enclosed at these limits by low mountains, the summits 
of the passes through which are 400 and 500 feet above the base. The plain is covered with 
irregular spurs, ridges, and isolated peaks, rising a few hundred feet, limiting it in a north 
and south direction sometimes to a space of a few hundred yards, and at others to that of ten 
miles. These spurs, &c., on the eastern portion of the plateau, are sparsely covered with cedar ; 
on the western, heavily covered with pine. 
There is no drainage from this plain, the waters of a few small streams and springs forming 
grassy ponds upon its surface. In its general features it is similar to the Great Basin, 
excepting that as more rain falls upon it, the vegetation is comparatively luxuriant. 
There are two routes by which this plain may be reached from the Great Basin, and the 
descent made to the Sacramento river. That by the Madelin Pass, the more northern, is 
most probably the better of the two, and is the only one necessary to be considered. Leaving 
Mud lake, it ascends by the valley of Smoky creek for three miles, through a narrow gorge 
(from 100 to 150 yards wide) in an outlying spur of the Sierra Nevada. 
After this the route is over more open ground, varying, in degree, to the summit of the pas- 
sage through the eastern ridge bounding the Sierra Nevada plateau. The pass is thus far of a 
very favorable character—the length of the ascent is 22.89 miles; the difference of elevation, 
1,172 feet; the altitude of the summit, 5,667 feet; and the steepest slope is 75 feet per mile. 
The plateau being gained, is crossed by a nearly level line to the low ridge bounding it 
on the west, the summit elevation of which, 5,736 feet, is attained by following a ravine valley. 
The descent to the Sacramento along one of its tributaries is now commenced, and is at 
