A diagram of Mount Mazama

This view is looking north from Oregon Highway 62 toward Crater Lake National Park from a pasture near Fort Klamath, Oregon.  Crater Lake fills a caldera that formed when Mount Mazama, a large volcano in the Cascades Range, erupted and collapsed about 7,700 years ago. Before the eruption, Mount Mazama was probably about 12,000 feet high. Mount Scott, on the right side of the image, is 8,929 feet (Klimasauskas and others, 2002; Ramsey and others, 2000).