Book 30, Question 17
Why are lakes on the Canadian Shield so rocky and clear?
The Canadian Shield is a huge area of very old, hard rock.
The rock is mostly granite and similar kinds, which dissolve very slowly, so the lake water carries few dissolved minerals. With so few nutrients to feed algae, the water stays clear. Because there is little limestone to balance acid, many Shield lakes are slightly acidic and can be sensitive to acid rain. These lakes are famous for cottages, canoes, and loons.