160 GUIDEBOOK OF THE WESTERN UNITED STATES 
be seen. The granite cliffs of Cochise’s Stronghold border a deep 
valley extending far into the Dragoon Mountains. Here the Apache 
Indians had a most useful hiding place, easily defended against every 
approach. Gerénimo fled here after his depredations and murders 
in Sulphur Spring Valley. 
The valley-fill materials revealed in cuts, badlands, and deeply 
gullied slopes are mostly fine pale reddish-brown sand and loam with 
a few beds of coarser materials. The brownish loam predominates, 
with nodular layers and beds of harder sandstone projecting from it. 
The lower beds well exposed east of Benson are reddish clay. This 
succession is about 900 feet thick in the valley slopes, and several 
hundred feet additional is known to underlie the valley floor at 
Benson, although above and below that place some of the underlying 
granite and schist are bared near the river. The sands and clays are 
deposits of former streams and lakes, which occupied the valley for a 
long time. They lie nearly horizontal near the center of thevalley and 
grade laterally into coarse deposits (Gila conglomerate) consisting of 
detritus from the adjoining mountain slopes and for the most part 
considerably tilted. In the clays have been found numerous remains 
of animals such as horses, elephants, mastodons, camels, deer, llamas, 
carnivores, various rodents, several reptiles, the tortoise G/ etches um, 
and several species of birds which have been described by J W. 
Gidley. Many are new species, and some are South American types. 
They are regarded as of late Pliocene age and indicate a warm, moist 
climate, probably subtropical. This faunal assemblage is very different 
from the present one and has been extinct for many thousands of years. 
In the fine-grained deposits in the southern part of the valley are 
deposits of gypsum and thick bodies of diatomaceous earth consisting 
largely of diatoms, minute siliceous skeletons, mixed with volcanic ash. 
The San Pedro River, which is crossed a short distance east of 
Benson, flows into the Gila River near Winkleman, nearly 100 miles 
to the northwest. It is a small stream when not in freshet but 
furnishes water for irrigation at several places, notably the old Mor- 
mon settlement of St. David, a few miles above Benson, established 
in 1878. Here also was the first artesian district in Arizona; the 
water is obtained from wells of moderate depth in the valley fill. 
Benson is a small commercial center and junction point for a branch 
railroad up the valley to connect at Fairbank with branches to 
B Tombstone and Patagonia. The Southern Pacific 
doe ae. south line (by way of Douglas) is on the bench 3 
Pern a miles west of Benson. In the San Pedro Valley are 
Ss mpd ruins of dwellings and pottery and implements 
‘Spanish explorers from Mexico. According to Sauer and Brand ® 
rome of the settlements were of considerable extent. 
oo Sa Pubs. in Aoupohi' vol. 3, No. 7, 1980. 
