Mount Mazama began to grow half a million years ago. The oldest rocks visible today, 420,000 years old, formed Mount Scott on the east side of Crater Lake. Over time, lava flowed from many volcanic vents, overlapping and building an irregularly shaped mountain. By 8,000 years ago, Mount Mazama may have stood as much as 12,000 feet (3,660 meters) tall. The peak has a mantle of pumice that was ejected during the climactic eruption of Mount Mazama.

Mount Scott is about 420,000 years old, and represents the oldest remnant of Mount Mazama. At 8,622 feet in elevation, it is the highest peak in the park. One or more snow avalanches created the long buff-colored scar descending down the flank of the peak.

Credits and Sources:

"Geology," National Park Service, http://www.nps.gov/crla/planyourvisit/upload/Geology.pdf (accessed November 4, 2015).

"Crater Lake National Park Geologic Resources Inventory Report," National Park Service, http://www.nps.gov/crla/learn/nature/loader.cfm?csModule=security/getfile&pageid=666498 (accessed November 4, 2015).