During a study of the geology and ore deposits of the Magdalena mining district in the central part of New Mexico for the United States Geological Survey in cooperation with the New Mexico Bureau of Mines and Mineral Resources, the writers obtained the data here presented. The manuscript was submitted for criticism to Kirk Bryan, who has done much work in the surrounding country, and the authors are indebted to him for valuable suggestions and for hitherto unpublished data on the area east of the Magdalena Range.
The district covers the northern part of the Magdalena Range and a small area just north of it; its geographic and geologic relations to the surrounding region are shown in Figure 1. The area studied in detail is shown in Figure 2.
The district is in the southeastern part of the Basin and Range Province and possesses features typical of the maturely . . .