The Sweetwater Roadless Area lies between Yerington, Nevada, and Bridgeport, California, along the California-Nevada boundary. The area encompasses approximately 72,240 acres in Toiyabe National Forest in Mono County, California, and Lyon and Douglas Counties, Nevada.

This roadless area, which lies just east of the Sierra Nevada range, exhibits rugged topography. Elevations range from about 6,160 feet near Devil's Gate to 11,673 feet at Mount Patterson.

Geochemical sampling was conducted during 1978, 1979, and 1980. This report summarizes the results of that investigation and provides details of the geochemical evaluation used in producing the final mineral resource assessment of the study area (Brem and others, 1984).

Map A shows the locations of all sites where rock samples were collected for this report and the distributions of anomalous concentrations for 12 elements in the 127 rock samples collected. In a similar manner, map B shows the collection sites for 59 samples of minus-60-mesh stream sediment, and 59 samples of nonmagnetic heavy-mineral concentrate derived from stream sediment and also shows the distributions of anomalous concentrations for 13 elements in the stream-sediment samples and 17 elements in the concentrate samples. Map C shows outlines of those drainage basins containing samples of stream sediment and concentrate with anomalous element concentrations and also shows weighted values for each outlined basin based on the number of elements with anomalous concentrations in each stream-sediment and concentrate sample and on the degree to which these concentrations are anomalous in each sample.