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.
Of historic significance, this report includes the first detailed topographic survey of the area, the work for which was conducted in 1913. Also, field work in the districts took place in about 1913 to 1915, and the histories of the mining districts are included. Photographs of the area taken during the field work are included as plates in the report. Thus, through this report histories of 100 years ago are preserved.
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. In the Supplement is a list of mining claims in alphabetical order.