markers (IMAGE) Johannes Gutenberg Universitaet Mainz Caption The comparative ratios of various marker substances in speleothems can be used to determine the type of vegetation that was present at a certain time above the cave. Credit ill./©: Research group of Thorsten Hoffmann Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. No derivatives or adaptations of the work are permitted. License CC BY-NC-ND 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.