156 GUIDEBOOK OF THE WESTERN UNITED STATES 
Railroad Pass, is at Raso siding, where an elevation of 4,376 feet 
is attamed. A short distance south of this siding are mountain 
slopes of schist and granite, and at the divide there is a cut in gravel. 
The foot of the Pinalefio Mountains lies a few miles north, and Mount 
Graham is discernible in the distance. To the west is a short descent 
to Willcox, in Sulphur Spring Valley, across which the Winchester 
Willcox ountains are visible. Sulphur Spring Valley was 
: named from a sulphur spring at the foot of a small 
Pavan butte 20 miles south of Willcox. Established in 
New Orleans 1,410 1880, Willcox was named for Gen. O. B. Willcox, at 
ae that time commander of the military department 
of Arizona and southern California (1878-82). : 
Sulphur Spring Valley is a wide, nearly level-floored basin 130 
miles long, with no outlet stream, which receives the drainage of a large 
area of surrounding slopes and mountains. In it there has been 
deposited a thick accumulation of sand, gravel, and loam. Much 
water passes underground in this material, and about Willcox and for 
some distance north there are scores of wells which obtain from this 
source an abundance of pure, soft water for irrigation and domestic 
use. The land is fertile and the irrigated areas yield various farm 
products, notably pink beans, and fruits. Willcox is one of the largest 
cattle-shipping points in Arizona and the outlet for many sheep and 
much wool and mohair. In the center of the basin is a large, shallow 
flat of about 40 square miles, of irregular shape, known as Willcox _ 
Playa. In times of rainfall this playa becomes a shallow lake, but 
_ in dry weather, which usually prevails, it presents a wide expanse of 
glistening salt, covered in places by ponds of saline water. Although 
there is little mineral matter in the run-off water from the mountains, 
it is all concentrated by evaporation in the central basin, of which the 
playa occupies the lowest part, and as this process has eon Biied for 
many centuries considerable saline matter has accumulated. Sedi- 
ments have been deposited at the same time, so that the basin now 
contains a thick succession of clay and silt and saline admixture. 
For a time this basin was occupied by a lake, which has been called 
Lake Cochise. It varied considerably in depth, but a zone of beach 
sands and sand dunes marks a shore line that persisted for a long 
period of inundation. Sand dunes of this old beach are conspicuous 
near Hado siding (ah’doe). Beyond this place is a broad flat of saline 
= deposits on which, at times, considerable water is visible on each side 
of the embankment on which the railroad passes. The playa is only 
__ about 3 miles wide near the railroad but widens greatly to the east and 
_ south. Frequently there are striking mirages on this playa in which 
_the great flat in the distance appears to be a huge lake with the buttes 
a the south rising as islands. 
dug in the So floor near Willcox and Cochise have revealed 
ts, camels, and bisons of oy Pleistocene = e 
