How is it that I grew up a science and nature freak in Canada and never heard about Lake Manicouagan? I had to learn about it from my new Oxford Satellite Atlas of the World (which makes great reading if you’re recovering from overindulgence in gardening). About 210 million years ago an asteroid 5 kilometres across hit what is now Québec and created a 100 km-wide crater (now a mere 70 km across due to erosion). The resulting global dust cloud blocked out the sunlight and wiped out 60% of Earth’s species. (This Triassic-Jurassic extinction event is not to be confused with the Cretaceous-Tertiary (or K-T) extinction event that totalled the dinosaurs.) The sudden removal of millions of tons of rock from the crater’s center caused a sudden “rebounding uplift” and what we have now (thanks in part to Hydro Québec) is a rare annular lake (or reservoir, if you want to get technical). Who knew?