Seismic Refraction (IMAGE) University of Wyoming Caption Seismic refraction data is collected from geophones that record the arrival of energy sent through the shallow subsurface by sledgehammer blows at the surface. Alec Spears (left) and Troy Covill were University of Wyoming students at the time of the study. Cliff Riebe, an associate professor in UW's Department of Geology and Geophysics, and his research team discovered that weathering of subsurface rock in the Southern Sierra Nevada Mountains of California occurs due more to rocks expanding than from chemical decomposition, as previously thought. Credit Russell Callahan 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.