Contact: Lisa Nelson Lisa.Nelson@nau.edu 928-523-6123 Northern Arizona University Research team says extraterrestrial impact to blame for Ice Age extinctions A colorized scanning electron microscope image of a glassy carbon sphere that contains evidence of extraterrestrial impact. The sphere measures about .012 inches in width. What caused the extinction of mammoths and the decline of Stone Age people about 13,000 years ago remains hotly debated. Overhunting by Paleoindians, climate change and disease lead the list of probable causes. But an idea once considered a little out there is now hitting closer to home. A team of international researchers, including two Northern...