BEIJING, July 8 (Xinhuanet) -- A 3-mile-wide comet that shattered over glaciers and ice sheets in Canda during the last Ice Age may have scattered diamonds and precious metals in the eastern United States and set North America on fire, leading to a mass die-off of animals and humans.

    New chemical analyses of diamond, gold and silver found in Ohio and Indiana reveal the minerals were transported there from Canada several thousand years ago. The question is, how?

    "There are no gold mines or silver mines in Ohio that anyone knows of, but there are plenty of them in Canada," said retired geophysicist Allen West, who was involved in the study.

    The discovery is consistent with a theory proposed by West and colleagues that a 3-mile-wide comet splintered over glaciers and ice sheets in eastern Canada about 12,900 years ago and wiped out man and beast.

    "These would have been like ten thousand Tunguskas going off at once," said West, referring to a mid-air explosion over Siberia a century ago possibly caused by a fragmenting meteor. "Some of them you couldn't see, and animals would've been breathing them in. But other ones would clearly have been visible. They might've even hurt if they hit you."

    The diamonds, gold and silver could have been ejected into the air during the blasts, West said, or they could have been carried south by rivers formed from the meltwater of liquified glaciers.

    Flaming fragments of the comet crashing to Earth sparked forests fires around the globe, West contends. The intense heat from the blasts set the very air on fire. North America's grassland, the furs of animals, the hair and clothing of humans — all would have been set ablaze.

    West and his colleagues have proposed that the comet strike contributed to the extinction of several species of North American megafauna, including mammoths and mastodons, and led to the early demise of the Clovis culture, a Stone Age people who had only recently immigrated to the continent.

    (Agencies)