According to a report in Live Science, the new chemical analyses of diamond, gold and silver found in Ohio and Indiana has revealed that the minerals were transported there from Canada several thousand years ago. "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.
The diamonds, gold and silver could have been ejected into the air during the blasts, or they could have been carried south by rivers formed from the meltwater of liquefied glaciers.
The researchers speculate that for several months following the comet strike, the skies rained precious stone and metals.
Diamonds drizzled down by the tons.
"Some of them you couldn't see, and animals would've been breathing them in," West told LiveScience. "But other ones would clearly have been visible. They might've even hurt if they hit you," he added.
According to West, the larger diamonds were visible to the naked eye and dropped like hail stones within seconds of the blasts.
The smallest diamonds, the "size of cold viruses," would have lingered in the atmosphere for weeks or months, eventually wafting down to Earth like expensive snowflakes, he added.
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.
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.