Collecting Evidence (image) The Earth Institute at Columbia University Share Print E-Mail Caption Geochemists dated the crater by analyzing rocks thrown out when it exploded. Lead author Peri Sasnett contemplates a sample. Credit Brent Goehring/Lamont-Doherty Earth Observatory Usage Restrictions None Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.