I would like to know if Crater Lake (Oregon) is considered to be a Composite or a Shield cone? Since it is the result of subduction would it not be a Composite volcano? The references I have looked at refuse to come out with a definitive answer.

Keith Lay

Hi Keith,

Crater Lake (formerly Mt. Mazama) is a composite volcano. It is made up of many inter-bedded layers of lava and ash. It is important to note, however, that just being a subduction-related volcano doesn't necessarily mean that you will be a composite volcano. Although rare, there are a few basaltic shield volcanoes along some subduction zones.

Sincerely,

Scott Rowland

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