Rock Sample MA113 (IMAGE) University of California - Santa Cruz Caption UCSC researchers analyzed two rock samples collected in Eastern Antarctica in which alternating layers of calcite and opal reflect cyclic changes in the subglacial environment. Sample MA113 is 9 centimeters thick and comes from Mount Achernar Moraine on the side of Law Glacier. Credit Gavin Piccione Usage Restrictions For use only with news coverage of this research 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.