From towering volcanic peaks to shimmering hypersaline lakes, Mammoth Lakes is a place where adventure and geology come together in the most spectacular way. Beneath its scenic mountains, alpine lakes, and world-famous ski slopes lies the powerful story of the Long Valley Caldera a super volcano that dramatically reshaped the landscape hundreds of thousands of years ago. Today, visitors can experience this incredible volcanic legacy firsthand, from steaming fumaroles and glassy obsidian domes to volcanic islands rising from the waters of Mono Lake, all while enjoying unforgettable hiking, kayaking, biking, and skiing adventures in the great outdoors.

Mammoth Mountain

One of California’s most popular and iconic volcanoes, Mammoth Mountain’s gondola-accessed promontory sits at an elevation of 11,000 feet above the town of Mammoth Lakes and provides visitors with unparalleled views and outdoor recreation throughout the year. This geologically young mountain was formed by a series of violent eruptions that occurred roughly 110,000 to 55,000 years ago as proof of the geologic unrest in the Eastern Sierra. Each of the many individual eruptions left layers of volcanic rock called rhyolite and dacite, with distinctly coloured intervals of rock representing separate tectonic events. While the volcano itself is no longer considered active today, the mountain is still alive with evidence of an explosive past. Fumaroles discharge steam and volcanic gases from the flanks of Mammoth Mountain and on the southwest side in the Mammoth Lakes Basin, as well as releases of carbon dioxide, have killed the forests around Horseshoe Lake.