What really killed the dinosaurs?
with Dr. Mark Richards
Saturday August 20, 2016 at 11:00 AM
159 Mulford Hall, UC Berkeley
The disappearance of the dinosaurs, along with 70% of all species in the fossil record, about 66 million years ago is widely attributed to the Chicxulub impact in Yucatán, Mexico — a discovery credited to a Berkeley team led by Walter and Luis Alvarez. However, at the same time, one of the largest volcanic eruptions in Earth history, the Deccan Traps, was occurring in India — a coincidence that has confounded geologists for three decades, and is made all the more remarkable since the four most recent mass extinctions in Earth history all correspond very closely in time to huge volcanic eruptions. Several new lines of evidence, including high-precision radioisotopic dating work at Berkeley, now suggest that the Chicxulub impact accelerated the Deccan Traps eruptions right at the time of the dinosaurs’ extinction. It is therefore difficult to know whether T. rex and friends were exterminated mainly by the impact itself or by the impact-triggered Deccan eruptions, since both events would have affected the environment in similar ways. So the great murder mystery once considered “solved” by the impact theory will require further research to sort out the true kill mechanisms for what appears to have been a double-edged catastrophe 66 million years ago.
Mark Richards earned his BS in engineering at the University of Texas, Austin, and his MS in physics and PhD in geophysics from the California Institute of Technology. He was a postdoc at Australian National University and served on the faculty at the University of Oregon prior to moving to UC Berkeley in 1989. He served as Dean of Mathematical and Physical Sciences from 2002-2014 and also as Executive Dean of the College of Letters and Science from 2006-2014, before returning to full-time research and teaching in the Department of Earth and Planetary Science. Professor Richards is a geophysical modeler and observer, focusing on the effects of large scale dynamic processes in the interiors of the terrestrial planets upon surface phenomena ranging from plate tectonics to large-scale volcanism. Recently, Professor Richards and his colleagues have suggested that one of the largest volcanic eruptions in Earth history, the Deccan Traps of India, was accelerated by the impact in Yucatán, Mexico, and that both events may have contributed to the great Cretaceous-Tertiary mass extinction. Professor Richards is a Fellow of the American Geophysical Union and the California Academy of Sciences, and has won the National Science Foundation’s Presidential Young Investigator Award. He is also the PI for the NSF-funded California Alliance (Berkeley, Caltech, UCLA, Stanford) project promoting diversity at the graduate, postdoctoral, and professorial levels in the mathematical and physical sciences. He has won Berkeley’s two highest awards for contributions to diversity, the Academic Senate’s Leon Henkin Award and the Chancellor’s Award for Institutional Excellence. This free public talk is presented as part of the monthly “Science@Cal Lecture Series” Event Contact: email@example.com