Paleozoic Sedimentary Rock (IMAGE) The Hebrew University of Jerusalem Caption Showing the Paleozoic sedimentary rock sequence at the Grand Canyon - from which samples were collected for this study. The steep cliffs are of marine limestone or dolomite formations. Credit Uri Ryb 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.