Thursday, May 17, 2007

Did comet start deadly cold snap?
A comet or some other extraterrestrial object appears to have slammed into northern Canada 12,900 years ago and triggered an abrupt and catastrophic climate change that wiped out the mammoths and many other prehistoric creatures, according to a team of U.S. scientists.

Evidence of the ecological disaster exists in a thin layer of sediment that has been found from Alberta to New Mexico, say the researchers, whose work adds a dramatic and provocative twist to the decades-old debate about the demise of the mammoths, mastodons and sloths that once roamed North America.

The sediment layer contains high concentrations of iridium, fullerenes and other compounds associated with space rocks and impacts, says Luann Becker, a geologist at the University of California, Santa Barbara, who has been analyzing the sediments.

Interesting, but I remain skeptical. For one thing, mammoths seem to have gone extinct over time from south to north rather than north to south as one would expect from a far-northern impact (or from overkill; don't have the refernece handy though).