|The road to the top of the dome|
Mammoth Mountain is as renowned for being part of a volcano as it is for its skiing. The Long Valley Caldera, a colossal volcano in the eastern Sierra Nevada region, is an area of extreme volcanism. Volcanoes have been erupting here since long before its last climactic eruption 750,000 years ago, and the last eruptions are as young as a few hundred years. This final eruption erupted approximately 600 cubic kilometers of material and resulted in the subsidence of the crust between 2 and 3 kilometers to create the current caldera. This particular feature, Obsidian Done, is related to the volcanics here but is from a different system: the Mono-Inyo crater chain.