ARIZONA (from the former Papago lo cality of Arizonac, or Arizonaca, probably meaning °place of small springs,* a few miles from the present Nogales, where some celebrat ed nuggets of silver were discovered in 1736 41. It has no connection with °arid zone,* etc.). A State of the United States (Western or Pacific group), bounded by Utah and Ne vada on the north, New Mexico on the east, Mexico on the south, Nevada, California and Lower California on the west. It extends from lat. 31° 20' to 37° N. and from long. 109° 2' to 114° 35' W. Land area, 113,810 square miles (72,838,400 acres), thus ranking fifth in size among the States. Pop. (1910) 204,354, (1917, est.) 263,788; males, 58.4 per cent. The capital is Phoenix.
Topography and Topographi cally Arizona presents two great divisions: a plateau region in the north, made up of ap proximately horizontal strata; and the moun tainous region in the south, consisting of up lifted strata plicated and folded with mineral rocks and intrusive veins. These mountain ranges are numerous and have a general north west and southeast trend, with intermediate broad valleys often 20 to 30 miles wide. The chief mountain masses are the Castle Dome, Big Horn, Eagletail, Chocolate, Dome Rock, Palomas, Harquahala and Harcuvar in the southwest; the Aquarius and Colorado in the west; the great plateaus rising in what are sometimes called the Northside Mountains in the northwest; the San Francisco and Black in the north central ; the Carrizo, Lukachukai and Tunicha in the northeast; the Zufii, White, Mogollon and Apache in the east; the Gila, Peloncillo, Pinalefio, Dragoon, Galiuro, Santa Catalina, Huachuca and Baboquivari in the southeast and south. The isolated volcanic San Francisco Mountains above Flagstaff are the highest of all, rising in their greatest height to 12,794 feet, and in Humphrey Peak to 12,562 feet. The other important peaks in the State are Thomas, 11,496 feet; Escudillo, 10, 691; Graham, 10,516; Ord, 10,266; and Greens, 10,115, while many others exceed 5,000 feet. To the south the surface falls sharply to low ridges, mostly volcanic; thence by terraced mesas to a great desert plain little above sea level, cut by Bullied stream-beds drawing the occasional rainfall to the broad and shallow Gila. The great northern plateau, or series of
plateaus, range in altitude from 5,000 to 7,500 feet; rising from them are numerous moun tain spurs, buttes and the cones of extinct vol canoes, while the Colorado River has cut through 6,000 feet of strata, exposing forma tions down to Carboniferous and Tertiary marine strata, underlying Tertiary lake sedi ments and later alluvium; indeed it has been said that every period of the world's history since the dawn of- life is represented in the geology of Arizona. The surface of the land as it lies was formed by a huge Eocene uplift, the water action afterward cutting the gorges and shaping the mesas and buttes; another took place in the Miocene, with eruptive volca noes. Near Holbrook, Navajo County, is a wonderful chalcedony forest (see FOREST, PET RIFIED), with prostrate trunks four feet thick cracked into exquisitely colored blocks. Every where a feature of the landscape in the north ern section is the great isolated mesas of sandstone with scarped and pinnacled sides, often more than 1,000 feet in sheer height. Most of the stream courses are dry save in the rainy season, and even then their flow is some times swallowed by the sands. The one con siderable river is the Colorado (q.v.) which flows generally southwest from Utah for 400 miles through the famous Grand Canon of Ari zona (q.v.), one of the wonders of the world, then turning south, forming the western bound ary of the State until shortly before it reaches the Gulf of California. Its chief affluent in the State is the Gila, which flows entirely across its southern portion; other tributaries are the Vir gin, which crosses the extreme northwest cor ner; the Colorado Chiquito or Little Colorado in the north, and Bill Williams fork in the west. Important tributaries of the Gila are the Salado, or Salt, and the Verde from the north and the San Pedro from the south.