Casa Diablo Hot Springs in eastern California, near Mammoth Lakes in the Long Valley Caldera, has long been shaped by its geothermal setting. Once known for a regularly erupting geyser, it was also an important Native American obsidian mining and manufacturing site from as early as the Millingstone Horizon, with stone traded as far as the coastal Chumash. In 1878 it became a stage stop on the Bishop Creek to Bodie route, serving nearby mining camps, and after closing in 1881 it continued in various commercial uses. Since 1983, the site has also been home to the Mammoth Geothermal Complex, linking prehistoric trade to modern energy production.