22 
POOLE’S SURVEY FROM SAN DIEGO TO FORT YUMA. 
indication of water on this portion of the line. It disappears a few rods below the border of 
the marsh, and the sandy creek again becomes dry. 
The slopes of this valley offer every facility for the location of the road, being broad inclined 
planes, composed of coarse gravel and sand, derived from the washing and wearing down of 
the mountain sides. Over the long, straight portions of this line a grade of 200 feet to a mile 
might with safety he adopted, though that of the whole line, from the station at Oak G-rove to 
the village, a distance of 8.92 miles^ is fixed at 106 feet, arriving on the slope behind the 
Indian huts at a point 22 feet above the level of the wagon road. 
Half a mile before reaching the village water again appears in the form of springs. It is 
considered inferior in quality, and has a peculiar taste, due to the presence of alkaline or other 
salts. Vegetation here consists only of some varieties of cactus, sage, and a few samples of low 
inesquite and stunted cedar hushes. Far up the valley of “ Volcan,” which enters the valley 
nearly opposite this point, may be seen, however, dark forests of pine timber crowning the 
hill tops. These are ten miles off, hut transportation to this point is not difficult. 
From the Indian village two routes were surveyed to the open plane of the desert. The first 
was by way of the wagon road, as at present travelled, and the other through a canon which 
conducts the waters of San Felipe into an adjoining valley leading directly to the desert. 
The results obtained by the former do not vary materially from those obtained by Lieut. 
Williamson in his examination of the same ground in 1853, though they are not, of course, 
identical with them in every respect, owing to the different methods of observation pursued. 
An inspection of the tables appended to this report will serve to show, when compared with the 
data furnished by the survey of that officer, the slight difference between the measurements of 
altitudes by the barometer and those of the spirit level. 
FROM SAN FELIPE TO THE COLORADO RIVER, BY WAY OF THE WAGON ROAD. 
Reports of this route having been frequently made by officers in the service of the govern¬ 
ment, it will he only necessary to briefly allude to its characteristic features. The face of the 
country throughout this distance of 125 miles may he described as a desert, though the name is 
generally only applied to the level portion of the route. For forty miles before reaching the 
open expanse of the desert the road traverses sandy canons and sterile basins, hounded on all 
sides by hare and rocky mountains, without enough of earth to cover their nakedness. Water 
is found only at distant points, and the absence of this element, combined with the intense 
heat, gives to the landscape a desolate and forbidding aspect. 
From San Felipe the road commences a gentle ascent, and leaves the valley at a distance of 
5.59 miles, at a grade of 36.8 feet per mile, passing a narrow ridge 50 feet in height, requiring 
a cut through rock of 450 feet in length. Crossing a small basin at a grade of 30.5 feet, we 
come to the entrance of a canon at 2.46 miles. This canon, which is extremely crooked, has 
a grade of 189.16 feet per mile for 1.42 miles, which, by resorting to the side hills, may he 
reduced to 100, making it necessary to cut and fill a series of rocky spurs and narrow ravines. 
From the foot of this canon to the puerto or pass, beyond which there is no obstruction, the 
natural surface has a grade of 96.5 feet a mile, which would he increased to about 100 if the 
side hill location above he adopted. From the mouth of this pass, which is a mile in length, 
and has a fall of 195 feet, the valley of Yallecitas has a regular descent at the rate of about 
