Lake Bosumtwi Sediment Core (IMAGE) University of Arizona Caption This sediment core taken from Lake Bosumtwi, Ghana has annually deposited layers. These layers provide a high-resolution chronology for the sediments and a means of reconstructing past climate variations. A meter stick lies alongside the core for scale. Credit T.M. Shanahan and W. Wheeler. Usage Restrictions The photo may be used only to illustrate a story about the research described in this news 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.