What volcanic events formed Crater Lake, OR? When did they take place?
A. A powerful explosion blew away the top of a stratovolcano; 10 million years ago.
B. The crater of a large, extinct cinder cone filled with water; 5 million years ago.
C. Landslides and volcanic mudflows dammed the Mazama River; 500 years ago.
D. Caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago.
Answer:D
What volcanic events formed Crater Lake, OR? When did they take place?
A. A powerful explosion blew away the top of a stratovolcano; 10 million years ago. B. The crater of a large, extinct cinder cone filled with water; 5 million years ago. C. Landslides and volcanic mudflows dammed the Mazama River; 500 years ago. D. Caldera collapse followed major ash and pyroclastic-flow eruptions; 6000 years ago.