Petra, That paste on the Geology of Catalina Island is highly inaccurate. I won't bother to explain why, unless someone asks. Yes, there are volcanic rocks on Catalina, probably 15-20 million years old as someone (Canie) suggested, and there are metamorphic rocks that were subducted and then later exumed. I (and others) think Catalina Island, as is the case with all the offshore California Islands, is there because it is actively uplifting.

Chris