Tuesday, September 25, 2007

Megafauna impact event update Research team says extraterrestrial impact to blame for Ice Age extinctions
“The detonation either fried them or compressed them because of the shock wave,” said Ted Bunch, NAU adjunct professor of geology and former NASA researcher who specializes in impact craters. “It was a mini nuclear winter.”

Bunch and Jim Wittke, a geologic materials analyst at NAU, are co-authors of the paper, which fingers an extraterrestrial impact 12,900 years ago for the mass extinctions at the end of the Ice Age. The paper was just released online in the Proceedings of the National Academy of Sciences. The research team includes several members of the U.S. National Academy of Sciences and researchers from Hungary and the Netherlands.

No one has found a giant crater in the Earth that could attest to such a cataclysmic impact 13,000 years ago, but the research team offers evidence of a comet, two and a half to three miles in diameter, that detonated 30 to 60 miles above the earth, triggering a massive shockwave, firestorms and a subsequent drastic cooling effect across most of North America and northern Europe.

About the only new thing here is the multi-impact angle. Still doesn't explain why some large herbivores (e.g., mammoth) would go extinct because of it while others (e.g., bison) didn't. But, that's pretty secondary; they've still got to convince people it actually happened the way they say it did. Then it's a whole other ballgame.