Geology
Geologically Rainy Lake is part of the Canadian Shield and retains features associated with it, such as a large, ancient caldera and a fault line that can be clearly seen in satellite images of the lake. The rock under the lake and exposed on many of its islands is an exposed part of the North American craton composed of ancient Precambrian rock. This rock has been significantly affected by glaciation, which dominates much of the recent geologic history of the area.
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