Crater Lake, Oregon

Crater Lake caldera (8,156 feet, 2,487 meters) was formed by a collapse during the catastrophic eruption of approximately 12 cubic miles (50 cubic kilometers) of magma, 6,845 years ago. The 5 mile by 6 mile (8x10 kilometer) caldera lies in the remains of Mount Mazama, a Pleistocene stratovolcano cluster covering 150 square miles (400 square kilometers) in the southern Oregon Cascades. Prior to its climactic eruption, Mount Mazama's summit had an elevation between 10,800 feet and 12,000 feet (3,300 meters and 3,700 meters). Its southern and southeastern flanks were deeply incised by glacial valleys, now beheaded, that form U-shaped notches in the caldera wall. Crater Lake reaches a maximum depth of 1,932 feet (588 meters). Wizard Island Post-caldera volcanic landforms are present beneath the lake surface and poke through to form Wizard Island. The central platform, Merriam Cone, and Wizard Island are all andesite evidently erupted within a few hundred years of caldera's collapse.