Mammoth Mountain (USGS photo, Mangan)

Mammoth Mountain is a popular recreation area in the Eastern Sierra Nevada mountains, and is one of California's major volcanoes. The town of Mammoth Lakes is tucked up next to the volcano. It lies on the edge of the Long Valley Caldera, and at the southern end of the Mono-Inyo chain of lava domes and craters. The area generates a large amount of geothermal energy—note Casa Diablo geothermal plant in the foreground.