Newly discovered microscopic diamonds suggest that a comet crashed into North America 13,000 years ago, triggering devastating floods and fires that killed 35 species and wiped out human communities, reports the Los Angeles Times. Layers of "nanodiamonds," found in a number of regions in the country, were created by the crash some 65 million years after a much larger comet collision wiped out the dinosaurs, say researchers.
The scientists link the more recent comet to the beginning of a geological period called the "Younger Dryas"— also known as the Big Freeze. "There's no other way we can interpret the presence of these diamonds other than an extraterrestrial impact," said paleooceanographer James Kennett. "I've counted up 15 major things that occurred 12,900 years ago. I'd like somebody to explain that to me in some other way."