image: Team leader Paul Renne examines a sample of hardened volcanic ash, called tuff, from the main extinction level where impact debris are found. This image relates to a paper that appeared in the Feb. 8, 2013, issue of Science, published by AAAS. The paper, by Paul R. Renne at the Berkeley Geochronology Center in Berkeley, CA, and colleagues was titled, “Time Scales of Critical Events Around the Cretaceous-Paleogene Boundary.” view more
Credit: [Image courtesy of Paul Renne]