24 
POOLE’S SURVEY FROM SAN DIEGO TO FORT YUMA. 
The wide valley into .which, the creek enters offers superior advantages over the hasins of 
Yallecitas and Cariso creek, and has a great resemblance to that of San Felipe, the mountain 
slopes spreading out at their base forming broad inclined planes highly favorable to the location 
of the road. The channel of the water course has an inclination of about 60 feet per mile, to 
a narrow pass or gorge formed by the projection of a rocky spur a distance of 17.4 miles. The 
elevation of the track at the mouth of the canon, as proposed, will increase the rate of descent 
to about 80 feet per mile. 
Immediately after passing the gorge the open plain of the desert appears to the view, hounded 
on the right by the mountains of the peninsular range leading into Lower California. On the 
left and north the spurs from the same range are seen overlapping en echelon as far as the eye 
can reach. By skirting the mountains on the right any desired elevation for the track can he 
adopted, and will ensure the avoidance of the patches of drift sand which are sometimes 
encountered on the lower plain. 
From the gorge the proposed line runs along these foot hills to the base of a high mountain 
12.20 miles distant therefrom; then descending gradually to the plain in nearly a southeast 
course, it passes over a broad level flat of blue clay for 10.8 miles, when it reaches the arroyo 
of Cariso creek, which is always dry at this point. Crossing this channel we traverse the wide 
plain with scarcely an obstacle for 20 miles, and come to the deep channel of New river. Here 
water can he obtained by digging, and by the sinking of artesian wells an exhaustless supply 
can doubtless he procured. 
From New river to a point a few miles north of Cook’s wells, where the lofty sand ridges 
from the north terminate, the route will have a nearly uniform and slightly ascending grade 
over alternate sections of hard clay, loose gravel, and beach sand with pebbles. About 18 miles, 
in a direct line, brings the line to the mouth of the Grila, by keeping to the north of Pilot 
Knob and traversing the table land or upper terrace bordered by the sand hills of Cook’s wells. 
The entire distance from San Diego, by this route, is 189.10 miles. 
It is now demonstrated beyond doubt that no route across the desert can he carried to the 
northward of the point near Cook’s wells above indicated. 
My surveys of the United States public lands during the present year, under the orders of 
the Surveyor General, show the existence of an extensive range of lofty sand hills or drifts rising 
from the plain to the average height of 350 feet, and from one to two miles in breadth Their 
direction is nearly northwest from Cook’s wells, and they are terminated only by the desert 
range of mountains on the north, which are 50 miles distant. This singular obstacle, unlike 
the smaller detached sand hills of the neighborhood, seems to he entirely composed of drift sand, 
and is not, like other sand ridges, based upon a terrace or hank of earth. The ground on both 
sides of it is about at the same level, and is divided into two hasins, which receive the drainage 
of several hundred square miles of territory. It was observed that the direction of the wind on 
the west side of the ridge was constantly from the northwest, while on the east side it blew from 
the north and northeast down the valley of the Colorado. Whether these winds are the cause 
of its formation is not a matter for present discussion ; hut the fact is plain that they offer a 
permanent obstacle to the construction of a railroad. It is evidently necessary to turn this 
harrier by passing to the south of it, where it subsides into the general level of that part of the 
desert. 
