The Cananea Mountains are situated in the north central part of Sonora, Mexico. At the eastern base of the range is the town of Cananea (approximately 31° N. Lat.; 110° W. Long.), about 25 miles south of the international boundary and 38 miles southwest of Naco, the port of entry from the United States.
Sporadic mining has been carried on in this region since before the eighteenth century, but never on a large scale until after the formation of the Cananea Consolidated Copper Company at the beginning of the present century. Since that time there has been more or less continuous production, which increased considerably during the period from 1928 to 1931 because of the high price of copper and the discovery of a new high-grade ore body.
Coincident with the development of the mines, several geologists1 made studies of the rocks and ore bodies. In 1907, a systematic . . .