SECTION VII. 
From Rio Colorado to the Pacific. 
The lofty crest of the Sierra Nevada, which forms the distinguishing topographical feature of 
California, extends uninterruptedly through five degrees of latitude, from Madeline Pass on the 
north, to Walker’s Pass on the south, the latter being in latitude 35° 40’. Between these 
points, it appears to be conceded that there is no break in the chain available for a railroad 
route. A secondary range of mountains, called the Coast range, dividing the waters of the 
Salinas from those of the San Joaquin, extends southeast from Monte Diablo to a point south- 
west from Walker" e Pass ; where, in latitude 34° 30' about, it intersects with a third great range. 
The latter commences at Point Conception, and extends* east-southeast to San Bernardino; and 
thence, according to recent explorations, is prolonged to the Colorado, near the junction of Rio 
Gila, and forms the northeast boundary of the California desert. South of San Bernardino 
commences another system of mountains, which traverses the whole length of Lower California, 
These various ranges are all united by low hills and ridges that are confined to a belt, about a 
degree and a half in width, bounded on the north by the parallel of 35? 15', and upon the south 
by latitude 33? 45' ; and among these connecting links are to be found the few available passes 
leading from the Colorado river to Los Angeles or San Francisco. 
The vapors that rise from the coast are generally precipitated upon the western slopes of the 
mountain ranges referred to; and therefore, south of the parallel of 36°, there is no stream, 
worthy of note, flowing from their bases eastward, save the Mojave river. This stream was 
formerly supposed to empty into the Colorado, near the Mojave villages; and, when our survey 
was projected, we believed it would lead by a favorable course the whole distance from that 
place to the eastern base of the Sierra Nevada. It now appears, however, from the examinations 
of Lieutenant Williamson—and subsequently those of Lieutenant Parke—that the Mojave river 
is lost at Soda lake. Hence, the region it traverses forms a basin belonging to the same system 
as those that are so celebrated further north. It is separated from the valley of Rio Colorado by 
a wide granitic mass, called the Painte mountain, which seems to be a prolongation of the 
Wasatch range. The slopes upon the east are so regular and smooth as to appear like a nearly 
level plain. Upon the summit there are but a few crested ridges, and the topographical sketches 
show passes, north and south of our line, lower than that upon which the levels were taken. It 
is believed that a more extensive exploration would discover a route across this ridge, by which 
the grades to Soda lake would not exceed 80 feet per mile. 
The region in the vicinity of the junction of the great mountain ranges that bound the Pacific 
slopes of California, within the belt above referred to, was explored by Lieutenant Williamson ; 
and the passes which he surveyed are described in his report. I beg leave briefly to refer 
to a few of them, as they have an important bearing upon the termination of the route under 
consideration. 
The best of the passes examined by Mr. Williamson are the San Gorgonio, at the junction of 
the Lower California range of mountains with the San Bernardino range; New Pass, through 
the latter range ; and Taheechaypah Pass, through the ridge dividing the so-called Great Basin 
from the head of Tulare valley. San Gorgonio Pass is available only to connect the Gila route 
with Los Angeles or San Diego. In the prolongation of this line to San Francisco, it is neces- 
9 This general sketch does not refer to the geological divisions, or strike of the mountain ranges, but simply, the 
direction of the masses. 
