Crater Lake Deepest point 1 949 Crater Lake

Crater Lake

Deepest point = 1, 949’

Crater Lake History 1. Built on older shield volcano 2. Growth of Mt. Mazama composite volcano 3. Glacial erosion (concurrent with volcanism) 4. Explosion craters fill with domes 5. Massive eruption of Mt. Mazama and subsequent caldera formation 6. Resurgent volcanism in caldera

Shield Volcano

Basaltic andesite flows

Crater Lake

Basin and Range Structure Crater Lake

Crater Lake Bimodal volcanism

Crater Lake History 1. Built on older shield volcano 2. Growth of Mt. Mazama composite volcano 3. Glacial erosion (concurrent with volcanism) 4. Explosion craters fill with domes 5. Massive eruption of Mt. Mazama and subsequent caldera formation 6. Resurgent volcanism in caldera

Garfield Peak Mount Scott Applegate Peak

Andesite and Dacite

Phantom Ship

“Phantom Ship” (andesite flow)

Caldera wall showing lava, cinders, and pumice layers

Pumice Castle

Mount Mazama prior to collapse 1500 m 9 km

Crater Lake History 1. Built on older shield volcano 2. Growth of Mt. Mazama composite volcano 3. Glacial erosion (concurrent with volcanism) 4. Explosion craters fill with domes 5. Massive eruption of Mt. Mazama and subsequent caldera formation 6. Resurgent volcanism in caldera

Glacial valley filled by lava flow Base of glacial trough

Kerr Notch Sun Notch

Glacial Striations