Hill-Slope and Runoff Processes at Work (IMAGE) University of Oregon Caption Graphic shows how the combination of hill-slope erosion and precipitation-generated runoff over geological time create a landscape of orderly ridges and valleys. Credit Courtesy of Joshua Roering Usage Restrictions Please include credit 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.