Map showing geochemistry of stream sediments in the Jerry Peak Wilderness Study Area, Custer County, Idaho

The Jerry Peak Wilderness Study Area is about 25 mi south of Challis in Custer County, central Idaho (fig. 1). The study area contains 46,150 acres of land administered by the by the Bureau of Land Management and 1 sq mi owned by the State of Idaho, a total of 46,790 acres. Most of the study area is readily accessible by roads along tributaries of the East Fork Salmon River, especially Road Creek, Herd Creek, and Lake Creek. The southeastern part of the area can be reached from Road Creek by the road down Peck's Canyon and by roads from Thousand Springs Valley, southeast of the study area. Several access roads to past logging operations extend up Sage Creek and its tributaries in the southeast part of the study area. Access to points within the northern part of the area is facilitated by jeep trails that connect with Road Creek and lake Creek and by improved road that extends northward from Herd Lake. The study area is moderately rugged, with local relief approaching 2,000 ft. Jerry (10,010 ft), the highest point within the area, is a low knoll on a north-trending linear ridge (fig. 1). The ridge has not been glaciated, despite its relatively high altitude. Most of the area is thinly covered by grass and low shrubs; trees, for the most part, are restricted to valley bottoms or to local, small groves on hillslopes.