Co-Lead Scientists with Sediment Core (image) University of Massachusetts at Amherst Caption Co-authors Julie Brigham-Grette and Pavel Minyuk celebrate when drilling reached the bottom of lake sediments at a depth of 318 m below the lake bottom. At that point, drilling began reaching into the 3.6-million-year-old impact rock. Credit Photo courtesy of Tim Martin Usage Restrictions None 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.