Collecting samples (IMAGE) University at Buffalo Caption Scientists collect samples from boulders in Greenland. These samples contain chemical isotopes that can help scientists determine the ancient boundaries of the ice sheet. Credit Credit: Jason Briner Usage Restrictions This image may only be used with news stories discussing the research in the related press release. 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.