Ice Age Ends Smashingly: Did a comet blow up over eastern Canada? Sid Perkins Evidence unearthed at more than two dozen sites across North America suggests that an extraterrestrial object exploded in Earth's atmosphere above Canada about 12,900 years ago, just as the climate was warming at the end of the last ice age. The explosion sparked immense wildfires, devastated North America's ecosystems and prehistoric cultures, and triggered a millennium-long cold spell, scientists say. IT'S IN THERE. A layer of carbon-rich sediment (arrow) found here at Murray Springs, Ariz., and elsewhere across North America, provides evidence that an extraterrestrial object...