Site provides evidence for ancient comet explosionJOEY HOLLEMAN; McClatchy Newspapers Published: October 7th, 2007 01:00 AM
COLUMBIA, S.C. – For the second time in less than a decade, a South Carolina river bluff holds evidence pointing to a theory with history-rewriting potential.
Microscopic soil particles from the Topper site near Allendale might hold a tiny key to a big theory: that comet-caused explosions wiped out the mammoths and mastodons, prompted the last ice age and decimated the first human culture in North America about 12,900 years ago.
The comet theory first began generating a buzz at an international meeting of geophysicists in Mexico in May. The findings were published this month in the Proceedings of the National Academy of Sciences. They’re about to go mainstream, with a National Geographic Channel segment today. The History Channel will film for a future show at Topper this week.
“People are fascinated by it,” said Allen West, an Arizona geophysicist and one of the leaders of the comet team, who’s speaking Wednesday at USC. “It has diamonds and giant elephants and Indians. Any new catastrophe theory that comes along gets plenty of attention.”
The new theory holds that a comet broke apart in the atmosphere above what is now eastern North America, producing explosions and wildfires as the pieces smashed into the surface.
Scientists, led by Richard Firestone of the Lawrence Berkeley National Laboratory in Berkeley, Calif., took soil samples from throughout North America and in Belgium. In a layer dating to about 12,900 years ago, they found high levels of iridium, nanodiamonds and glasslike carbon that could have been caused by a comet explosion and subsequent fires.
The Topper site, on the Savannah River, provided compelling evidence, in part because of earlier findings by Al Goodyear of the S.C. Institute of Archaeology and Anthropology at USC.
Goodyear drew international attention in 2004 when stone points found at Topper that apparently were sharpened by humans (Clovis points) were carbon dated to nearly 50,000 years ago. That put human beings in North America thousands of years earlier than thought. For generations, scientists have thought the first humans arrived 13,000 years ago via a land bridge from Asia.
Goodyear’s work at Topper, along with similar finds in Brazil and Chile, prompted scientific reconsideration of when humans arrived in North America. It also led to skepticism by scientists who didn’t buy Goodyear’s theory. In that regard, he found kindred spirits in the comet group.
“This is a pretty wild theory,” Goodyear said with a chuckle. “I’m glad I’m not doing this one.”
He welcomed West to dig at Topper. At the same depth as Topper’s undeniable Clovis artifacts, West found high concentrations of iridium, nanodiamonds and glasslike carbon.
West’s findings prompted Goodyear to do his own study on the disappearance of Clovis points. These stone tools are found throughout North America only in soil dating back about 13,000 years or more.
Not long after that, a different style of points began showing up from people scientists have dubbed the Redstone culture.
Goodyear’s recent study found there were four times as many Clovis points as Redstone points at similar sites. That would indicate a huge population drop from the Clovis to Redstone cultures, possibly caused by some natural catastrophe.
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