Co-Sponsored by The Center for Ancient Studies, the Institute for Environmental Studies, and the University of Pennsylvania Museum of Archaeology and Anthropology

This program is made possible through the generosity of Mr. and Mrs. A. Bruce Mainwaring

Is our civilization threatened by meteorites? Although recent Hollywood movies such as Deep Impact and Armageddon are partially fanciful, we may actually be more likely to die from the next meteorite impact than from a commercial plane crash. Many of us watched the spectacle in 1994 as the Shoemaker-Levy comet crashed into the icy atmosphere of Jupiter. What might have happened if Shoemaker-Levy's final destination had been Earth?

How many of us have examined the cratered surface of the Moon through amateur telescopes or binoculars? Planetary geologists recognize that the impact of bodies from space has been an important process in shaping the surfaces of other planets. But we have been curiously reluctant to accept the very high probability that Earth history is also characterized by collisions with chunks of rock from elsewhere in the solar system. Scientists have, understandably, been hesitant to acknowledge the importance of events that occur so infrequently that they have never been directly observed by humans.

However, we have now identified about 200 impact craters on Earth. A conservative extrapolation from the data suggests that the Earth has sustained more than 2,000 massive impact events during the last two billion years, or one major event every million years. If the next impact were to occur in an ocean basin, a two-to-one probability, the resulting wave would destroy life hundreds of meters above sea level and hundreds of kilometers inland.

You are cordially invited to attend a public symposium on meteorite impact in Earth history. We will hear a compelling review of the history of meteorite impact on Earth by Professor John S. Lewis of the University of Arizona, and an account of the very recent discovery of the largest crater known in North America, the Chesapeake Bay feature, by Dr. Wylie Poag of the U.S. Geologic Survey.

A CRATERED EARTH
Robert Giegengack
Professor of Earth and Environmental Science, University of Pennsylvania

RAIN OF IRON AND ICE: THE VERY REAL THREAT OF COMET AND ASTEROID BOMBARDMENT
John S. Lewis
Professor of Planetary Sciences, University of Arizona

CHESAPEAKE INVADER: DISCOVERING AMERICA'S GIANT METEORITE CRATER
Wylie Poag
Senior Scientist, U.S. Geological Survey

COMMENTARY

WERE DINOSAURS DRIVEN TO EXTINCTION BY THE ASTEROID THAT PRODUCED THE CHICXULUB CRATER IN YUCATAN?
Peter Dodson
Professor of Anatomy, School of Veterinary Medicine, University of Pennsylvania

RATIONALIZATION FOR THE NEED FOR RESEARCH INTO THE IMPACT OF NATURAL CATASTROPHES ON ANTHROPOLOGY
A. Bruce Mainwaring
Former Chairman, Board of Overseers, University of Pennsylvania

THE WOLFE CREED CRATER: ITS DISCOVERY AND MEANING IN SCIENTIFIC AND ABORIGINAL LORE
Peggy R. Sanday
Professor of Anthropology
University of Pennsylvania

CLOSING REMARKS
Jeremy A. Sabloff
The Williams Director, University of Pennsylvania Museum of Archaeology and Anthropology

QUESTION AND ANSWER PERIOD

6:00 PM RECEPTION (SEPARATE FEE)