This Open-File Report consists of twenty-one 35-mm slides showing material that was presented at the Fourth Thematic Conference on Remote Sensing of the Environment held in San Francisco, California on April 1-4, 1985 (Purdy and others, 1985). The work was carried out in conjunction with the U.S. Geological Survey's Conterminous U.S. Mineral Appraisal Program for the Tonopah, Nevada 1° by 2° quadrangle (fig. 1). The slides show Landsat Multispectral Scanner (MSS) images, Landsat Thematic Mapper (TM) images, and geologic interpretations made from these data.