University of Oregon Scientists Propose Comet Impact Theory for North American Extinctions

Scientists are investigating a new theory that a large comet or other object collided with the Earth some 12,900 years ago, causing the disruption of the prehistoric Clovic culture and the extinction of numerous animals across North America, according to researchers leading a recent presentation at the University of Oregon (UO).

UO archaeologists Douglas J. Kennett and Jon M. Erlandson publicly detailed the theory for the first time earlier this month before a classroom packed with students and faculty. The theory has since been presented at the 2007 Joint Assembly of the American Geophysical Union held this week in Mexico.

Kennett and Erlandson are part of a multi-institutional, 26-member team proposing that a comet or other extraterrestrial object struck the Great Lakes region nearly 13,000 years ago and set off a wave of cultural fragmentation, animal extinctions and a thousand-year cold spell. The theory is based in part on the presence of a carbon-rich layer of soil found at about 50 sites occupied by the Clovis culture. The carbon layer contains elements and materials similar to those found in what is known as the K-T Boundary, a layer of Earth associated with the extinction of the dinosaurs at the end of the Cretaceous Period.

"Highest concentrations of extraterrestrial impact materials occur in the Great Lakes area and spread out from there," said Kennett. "It would have had major effects on humans. Immediate effects would have been in the North and East, producing shockwaves, heat, flooding, wildfires and a reduction and fragmentation of the human population."

A leading argument for the mass die-off of dinosaurs is that a large asteroid struck the Earth near the Gulf of Mexico at that time, sending clouds of choking, sun-blocking dust into the global atmosphere for such a long period of time that temperatures plummeted. The resulting period of cold darkness is believed to have wiped out numerous plant and animal species.