Ice Core 2 (IMAGE) Oregon State University Caption A volcanic ash layer in the WAIS Divide ice core. Volcanic markers like these were used in the new study to synchronize ice cores from across Antarctica. Credit Heidi Roop Usage Restrictions None 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.