Geology and ore deposits of the Platoro-Summitville mining district, Colorado. 122 pages. 40 plates (1:36,000). 2 figures. Digital PDF download. B-13D
Excerpted from the introduction:
The district covered by this bulletin is located in the mountainous region that forms the southeasterly extension of the San Juan Mountains and at or near the head waters of the Alamosa and Conejos Rivers. It lies in the southern part of Rio Grande County and in the northern part of Conejos County, the county line running a little north of the center of the mapped area, and is approximately forty miles west of Alamosa, the business center of the San Luis valley. It forms a small part of the Rio Grande National Forest. The area covered is something over fifty square miles.
This report includes the first detailed topographic survey of the area, conducted in 1913. Field work in the district took place between 1913 and 1915. The report is organized into the following chapters: Chapter I. Introduction; Chapter II. Topographic survey; Chapter III. Geology and petrography; Chapter IV. Summitville district; Chapter V. Platoro district; Chapter VI. Gilmore district; Chapter VII. Stunner and Jasper districts. Photographs of the area taken during the field work are included as plates along with a history of the district. A supplement contains a list of mining claims in alphabetical order.