Rock sampling in Yosemite National Park (IMAGE) University of California - Berkeley Caption In 2010, two of the study’s authors — David Shuster of UC Berkeley (left) and Yosemite Park geologist Greg Stock (right) — collected rock samples from the rim of Yosemite Valley, where the granite has eroded only slowly over the last 50 million years. In the distance is the upper Merced River valley. Former UC Berkeley graduate student Johnny Webb is at center. Credit Kurt Cuffey, UC Berkeley Usage Restrictions none License Original 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.