Crater lake
A crater lake is a lake that fills an impact crater or volcanic crater.
A crater lake forms when a crater fills with water from rain, snow or groundwater. Some crater lakes are in volcanic craters, but many famous ones fill impact craters.
Lake Bosumtwi in Ghana fills a crater about 10.5 kilometres across, formed about 1.1 million years ago. Pingualuit Crater in northern Quebec, Canada, about 3.4 kilometres across, holds a deep, very clear lake. The Kaali crater in Estonia, a few thousand years old, has a small lake in its main bowl. In Canada, the double lakes of the Clearwater Lakes were once thought to mark two craters made at once, but dating shows they formed at different times.
Crater lakes are valuable to scientists because their sediments build up layer by layer, preserving records of past climate. Cores drilled from Lake Bosumtwi, for example, contain a climate record going back about a million years. Many crater lakes are also beautiful places to visit.
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Level: Beginner Ages 7 and up