Rounding River Rocks (IMAGE) University of Pennsylvania Caption A new study by the University of Pennsylvania's Douglas Jerolmack, working with mathematicians at Budapest University of Technology and Economics, has found that rocks traveling down a riverbed follow a distinct pattern, first becoming rounder, and then smaller. Credit University of Pennsylvania Usage Restrictions In context of reporting 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.