Ajo lies in the Papago country of southwestern Arizona, in the Sonoran desert section1 of the Basin and Range province (Fig. 1). The region, which displays a wide variety of topographic forms, offers unusual opportunity for study to those interested in the physiography of arid regions because the United States Geological Survey has completed topographic maps, one of the Ajo quadrangle on the scale of 1: 48,000, and one of a few square miles in the mining area near Ajo on the scale of 1: 12,000.
The Ajo quadrangle includes the small mountain masses of the Little Ajo Mountains, Childs Mountain, and part of the Batamote Mountains. Much of the area is occupied by desert plains, of which the largest is the Valley of the Ajo. Altitudes range from 1,150 to 3,200 feet. Local relief is moderate and only exceptionally reaches 1,000 feet in a square mile. The climate . . .