176 GUIDEBOOK OF THE WESTERN UNITED STATES 
per cent of copper. When this ore was worked out new bodies of lower- 
grade ores were found which have continued to produce a large ton- 
nage, and in 1902 other ore bodies were revealed by the Calumet & 
Arizona mine. The workings are large and of considerable depth, but 
all lie in an area of less than a quarter of a square mile. (Ransome.) 
According to the United States Bureau of Mines about 32,250,000 
tons of material has been removed from Sacramento Hill, most of it 
low-grade ore. About 3,000 men are employed. The copper produc- 
tion of the several mines in 1929 was 186,130,352 pounds, which, to- 
gether with considerable gold, silver, and lead as by-products, had a 
value of $35,504,798. The most extensive ores are sulphides, oxides, 
4 sea level WaT 
Horizontal scale - vere scale 
a a ee . 2M oR 9 L i 1 lopcc Feet, 
Figure 45.—Section across the Bisbee region, Ariz. Ke, Limestones, sandstones, shales, and conglom 
erate of Lower Cretaceous age (Comanche); Cn, Naco limestone; Ce, Escabrosa limestone; D, 
Martin sas (Devonian); €a, Abrigo limestone; €b, Bolsa quartzite (Cambrian); sc, schist; 
gp, granite porphyry. After Ransome 
and carbonates. In 1929 their average value in metals was near $12 
a ton. 
The mean annual precipitation in this region is from 18 to 20 
inches. 
Naco * is in the wide Espinal Plain (es-pee-nahl’), which slopes 
west from the foot of the Mule Mountains into the broad valley of 
the San Pedro River. This river rises in Mexico, 
ene north, and finally empties into the Gila River. 
onan dee 4.78 feet. ‘The San Pedro Valley has had an interesting history, 
New Orleans 1,431 having long been a natural passageway for explorers, 
pat travelers, and Indians, including De Niza and Coro- 
nado. (See p. 150.) 
In 1692, on his first visit, Padre Kino (see pp. 161, 186) named the 
river Quiburi (kee-boé-ree) from a rancheria of about 500 Indians, 
near the river not far from Tombstone. It was the home of Coro, 
the head Pima chief, and it was here that Kino on the expedition of 
1697 found the Tudians dancing about some Apache scalps they had 
just obtained. Later American and Mexican settlers in the valley 
_ were greatly harassed by hostile Indians, until the final subjugation 
of the Apaches in 1886. The earliest Shariah settlers were four 
Mormon. families from the colony established near Mesa, Ariz., by 
In March, 1929, Naco, Mexico, | tionists, in which the latter, by the aid 
just across the boundary from Naco, | of bombs dropped from airplanes and 
ab was the scene of a severe sess attacks by tanks, were victorious. 
Naco. 
