Fossil Site in Sweden (IMAGE) Field Museum Caption These are cliffs made of sedimentary rock that was once an ancient seabed. The gray horizontal line in the rock shows where the dust from the asteroid collision fell. Credit (c) Field Museum, Philipp Heck Usage Restrictions Please include credit: (c) Field Museum, Philipp Heck 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.