Yellowstone 1 (IMAGE) American Geophysical Union Caption A researcher sits on a horizontal branch of a large living evergreen, wielding a T-shaped tree coring tool. Credit Grant L. Harley Usage Restrictions Use with appropriate credit. 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.