Sudbury Basin, Ontario
The Sudbury basin formed as a result of an impact into the Nuna supercontinent from a bolide approximately 6 to 9 miles in diameter that occurred 1,849 million years ago in the Paleoproterozoic era. Current evidence indicates that it was actually a comet because no asteroid remains have ever been found. It was traveling around 25 miles per second and punched a hole through the crust 22 miles deep, creating a crater over 150 miles wide.