Dr Stephen Grebby (IMAGE) University of Nottingham Caption Dr Stephen Grebby, lead study author from the Nottingham Geospatial Institute, University of Nottingham Credit University of Nottingham 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.