Atacama Desert Boulders (IMAGE) Geological Society of America Caption These are huge boulders in Chile’s Atacama desert which appear to be rubbed very smooth about their midsections, leading University of Arizona geologist Jay Quade to wonder what could cause this in a place where water, Earth’s most common agent of erosion, is as almost nonexistent. Credit Image courtesy of Jay Quade. Usage Restrictions Image for non-profit and media use only 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.