A Coinciding Asteroid and Extinction? (3 of 7) (image) American Association for the Advancement of Science Share Print E-Mail Caption 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." Credit [Image courtesy of Paul Renne] Usage Restrictions Please cite the owner of the image when publishing. This image may be freely used by reporters as part of news coverage, with proper attribution. Non-reporters must contact Science for permission. Share Print E-Mail 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.