This is a pair of craters so close to each other that they form one lake, and were long thought to have been formed by a pair of gravitationally bound asteroids, but analysis of the surrounding rock puts them about 180 million years apart. Source.
Turvey is the Canadian novel I'd most like to see made into a film. Hell, it's the Canadian novel I'd most like to make into a film myself. Go to Fly-by-Night for everything you want to know about English Canadian paperbacks in the 1940s and 50s.