Soil Excavation at Valles Caldera (IMAGE) University of Arizona Caption Researchers examine and photograph a cross-section of soil exposed within an excavation pit at the Valles Caldera National Preserve, N.M. From L to R: Scott Compton, hydrologist with Valles Caldera National Preserve; Jon Chorover, a UA professor of soil, water and environmental science; and Craig Rasmussen, a UA assistant professor of soil, water and environmental science. Credit Marcel Schaap, UA Dept. of Soil, Water and Environmental Science. Usage Restrictions This photo may only be used to illustrate a story about the research described in the accompanying news release, "UA Awarded $4.35 Million to Study Earth's Critical Zone." Please make sure to credit the photo as requested. Do not post this photo independent of the story. 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.