An amateur astronomer scanning satellite maps for a camping location in Quebec stumbled upon an unexpected find: a large, strange circle on the landscape. That circle turned out to be a massive impact crater, roughly 25 kilometers wide, that was blasted into Earth about 390 million years ago.
Scientists later verified the discovery by identifying shatter cones, distinctive rock formations that form only under the extreme pressure of a meteorite impact. The finding adds a newly recognized ancient impact site to the geological record, and it all began with a casual look at a map.