Ramzi Touchan, University of Arizona (image) University of Arizona Caption Ramzi Touchan of the University of Arizona's Laboratory of Tree-Ring Research teaches students techniques for taking tree-ring cores during his field work in Algeria. Credit Photo courtesy of R. Touchan, University of Arizona. Usage Restrictions This photo may be used only to illustrate a story about the research described in the release, 20th Century One of Driest in Nine Centuries for Northwest Africa. 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.