Jonathan Gilligan, Vanderbilt University (IMAGE) Vanderbilt University Caption This is the study's lead author, Jonathan Gilligan, associate professor of earth and environmental sciences. Credit John Russell/Vanderbilt University Usage Restrictions None License Licensed content 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.