Washington, Oct 8 : The theory that comet-caused explosions wiped out mammoths and mastodons, prompted the last ice age and decimated the first human culture in North America about 12,900 years ago, has received a boost for the second time in less than a decade.

Allen West, an Arizona geophysicist has said that microscopic soil particles from the Topper site near Allendale might hold a tiny clue in support of this theory.

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. Later a National Geographic segment brought them into the mainstream. The History Channel has also planned for a future show at Topper this week.

“People are fascinated by it. It has diamonds and giant elephants and Indians. Any new catastrophe theory that comes along gets plenty of attention,” said West.

According to the new theory, 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.

The scientists, led by Richard Firestone of the Lawrence Berkeley National Laboratory in Berkeley, California, 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, possibly caused by a comet explosion and subsequent fires.

The scientists said the Topper site, on the Savannah River, provided compelling evidence, in part because of earlier findings by Al Goodyear of the SC Institute of Archaeology and Anthropology at USC. (ANI)