Sea Cave Stratigraphy (IMAGE) Rutgers University Caption The stratigraphy of the sea cave in Sumatra excavated by scientists from the Earth Observatory of Singapore, Rutgers and other institutions. The lighter bands are sand deposited by tsunamis over a period of 5,000 years; the darker bands are organic material. Credit Earth Observatory of Singapore 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.