November 19, 2008
American Center for Physics
College Park, MD
Speaker: Luann Becker, Department of Physics and Astronomy, Johns Hopkins University
Time and Location Talk starts at 1:00 pm with Q&A to follow. It will be held in one of the first floor conference rooms at the American Center for Physics, One Physics Ellipse, College Park, MD. This is located off River Road, between Kenilworth Ave. and Paint Branch Parkway.
Abstract: It is well established that the last catastrophic faunal extinction in the geologic past coincided with the end of the Pleistocene during the deglaciation between the last glacial episode and the present Holocene interglacial. This was a time of massive loss in mammals at both the generic and species levels. The details of the timing of these extinctions remain unclear due to limitations of biostratigraphy and resulting questions as to when many of the taxa did become extinct within the last deglacial episode. Nevertheless, the available data strongly constrains the timing of the extinctions to a brief interval between the end of the last glacial episode and the beginning of the Younger Dryas, an interval of only 1500 yrs. Since this interval itself was so brief, it is no surprise that this event is widely equated as a mass extinction occurring ~13 ka immediately following the so-called Clovis interval of early human occupation in North America. The cause of this mass extinction has been debated for many years but remains highly controversial in part because of limitations of available data, but also because the two major hypotheses that have been long invoked - climate change and human over-hunting - have continued to present significant problems. In this talk, I will discuss evidence for an impact event that occurred ~13 kya. The closeness in the age of a major faunal extinction and abrupt cooling with the inferred extraterrestrial (ET) impact, if correct, raises the possibility of causal relations between these different phenomena; i.e. that the faunal extinction at least in part resulted from the ET impact event and that climate cooling was also triggered by the ET impact event.
B.S. (1983) Geology, Texas A&M University
M.S. (1993) and Ph.D (1995), Oceanography, Scripps Institution of Oceanography
NRC Post-Doctoral Fellow, NASA/AMES Research Center, Moffet, CA
Previously at: U Hawaii, U Washington, UCSB, Esso and Exxon
Member of the National Academies of Science Committee and Panels (Astrobiology, Origins and Evolution of Life, Organic Environments in the Solar System)
Member of the ACS, AAAS, ISSOL, AAPG, AGU
Recent Publications related to: evidence for the Younger Dryas impact event; organic matter in the Martian meteorite ALH84001; impact event at the 250 myr old Permian – Triassic boundary; Astrophysical and Astrochemical Insights into the Origin of Life.