Little ButteVolcanic Series FOOTNOTES Recalculated age varies raore than 5 percent from published age."Ananolous age: age appears to be either too old or too young, based on other geologic or geochronologic data. Check source reference for more specific information.c Data excluded from average. Approximate location.e Location not plotted on index map.

Under the provisions of the Wilderness Act (Public Law 88-577, September 3, 1964) and related acts, the U.S. Geological Survey and the U.S. Bureau of Mines have been conducting mineral surveys of wilderness and primitive areas. Areas officially designated as "wilderness," "wild," or "canoe" when the act was passed were incorporated into the National Wilderness Preservation System, and some of them are presently being studied. The act provided that areas under consideration for wilderness designation should be studied for suitability for incorporation into the Wilderness System. The mineral surveys constitute one aspect of the suitability studies. The act directs that the results of such surveys are to be made available to the public and be submitted to the President and the Congress. This report discusses the results of a mineral survey of the Ishi (B5098), Mill Creek (O5284), Polk Springs (O5097), and Butt Mountain (O5100) Roadless Areas in the Lassen National Forest, Tehama and Plumas Counties, California. The areas were classified as further planning areas during the Second Roadless Area Review and Evaluation (RARE n) by the U.S. Forest Service, January 1979. SUMMARY oApproximately 270,000 yd of inferred auriferous gravel resources were estimated in three Tertiary deposits in the Polk Springs Roadless Area (table 1). These resources are exposed between Paleozoic and (or) Mesozoic metamorphic rocks and tuffbreccia and lava flows of the Pliocene Tuscan Formation which suggests that although no deposits were identified in the other roadless areas, they may be concealed beneath the Tuscan Formation.Recent stream gravels of Deer Creek in the Polk Springs Roadless Area contain enough gold to attract gold hobbyists; however, the stream gravels do not have sufficient volume to be considered a significant resource. Potential exists for additional auriferous gravels near the Occidental mine in the Polk Springs Roadless Area.Bleached zones within the Tuscan Formation do not appear to have associated mineralization. Although geothermal activity near Lassen Peak does not extend as far south as the study area, Sulphur Lick, in the southern Ishi area, contains cold mineralized water.