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196 GUIDEBOOK OF THE WESTERN UNITED STATES 
pl. 22, B), which becomes conspicuous near Avra siding and is a land- 
ead for many miles in all directions. Its elevation is 3,374 feet. 
It consists of lavas steeply tilted to the north, and it may shoes include 
the neck or vent of an old volcano. The railroad passes very near 
this peak at Montrose and Wymola sidings. According to Garcés, it 
was called Cerro de Tacca by the Indians. Near it, in ancient days, 
was a Pima settlement or rancheria called Akutchiny (“mouth of 
the creek’’), located at the sink of the Santa Cruz River. 
In the pass a few rods east of Wymola siding there is a 10-foot 
monument just south of the tracks with the inscription ‘Lieut. J. 
Barrett and Privates G. Johnson and W.S. Leonard, 
Wymola. killed April 15, 1862, in the only battle of the Civil 
et =n, War in Arizona. Erected by the Arizona Historical 
fles. : Society and Southern Pacific Railway, April 15, 1928.” 
These men and a few others, members of the Cali- 
fornia Volunteers, had an encounter with Confederates who had just 
evacuated Tucson. 
The Picacho Mountains, a high rocky range rising out of the desert 
plain north of Wymola, culminate in Newman Peak (elevation 4,529 
feet). They consist of schist, all of which in this general region is 
believed to be of pre-Cambrian age. 
Beginning near Wymola and extending for about 5 miles west is a 
very fine assemblage of cacti, growing mostly on the rocky slopes 
along the south side of the railroad. There are many stately sahuaros, 
barrel cactus (biznaga), cholla (cho’ya), and other desert species. 
The region extending west from the San Pedro River to the Colo- 
rado River and the Gulf of California, constituting the northern part 
of the Province of Sonora, was known to the early explorers as Pimeria 
Alta (pe-may-ree’ah). When the Spaniards found that its northern 
and northwestern extension: was occupied by the Papago Indians they 
called this portion Papaguerfa (pa-pa-gay-ree’ah), to distinguish it 
from the region of the more sedentary Sobaipuris of the Santa Cruz 
and San Pedro Valleys. With a mean annual rainfall on the lower 
lands ranging from 3 to 10 inches and a mean annual temperature of 
67° at Tucson and 72° at Yuma, it is one of the warmest and most 
arid portions of the United States. In places the summer maximum 
temperatures are as high as 126°. The vegetation is a striking 
assemblage of peculiar plants in which large cacti, small desert trees, 
and many shrubs are present, but all widely spaced. No part of the 
region is so dry as to be without plants except a few areas of drifting 
sand. Where the ground water is near the surface, as in the wider 
plains subject to occasional flooding by rains, there is considerable 
mesquite, but this plant also grows in many places where the amount 
& of water is very slight for most parts of the year. Mesquite, like a 
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