Sediment core (IMAGE) Northwestern University Caption Calcium carbonate samples from a sediment core drilled from the mid-Pacific Mountains show evidence of ocean acidification 127 to 100 million years ago. Credit Northwestern University 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.