How was Crater Lake, Oregon formed?
A) caldera collapse of the top of Mt. Mazama after the eruption 7700 years ago partly emptied the magma chamber
B) when sea floor spreading permitted seawater to flood into the newly formed volcanic rift
C) as a remnant of the "great flood"
D) a prehistoric eruption of Mount St. Helens

Question

Quizplus · Accepted Answer

Crater Lake in Oregon was formed by the caldera collapse of the top of Mt. Mazama after a massive eruption approximately 7,700 years ago, which partly emptied the magma chamber beneath the mountain. This collapse created a large crater that eventually filled with rainwater and snowmelt, forming the lake.

How Was Crater Lake, Oregon Formed