Collected samples from drilling (IMAGE) University of Göttingen Caption The light-coloured volcanic ash, embedded between finely stratified lake clays of the intensively investigated research drilling Nördlingen 1973. Credit Gernot Arp, University of Goettingen 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.