Nanodiamonds Support Comet, Mass Extinction Theory

Scientist have discovered nanodiamonds that could indicate that part of a comet hit North America almost 13,000 years ago and set off a warming trend, according to an article in Science.

The nanodiamonds appeared to form in soil from Arizona, Michigan, Oklahoma, South Carolina, and Canada. They only occur in places exposed to massive pressure and extreme temperatures, which results from explosions or extraordinary impacts.

Before finding the diamonds, scientists believed that something impacted the Earth and triggered a 1,300-year cooling period in the Northern Hemisphere. That period is thought to have ended the warming that followed an Ice Age. Scientists also have found fragments of comets and high levels of iridium in layers that formed before mammoths went extinct thousands of years ago. That information also supports the theory that a comet struck the Northern Hemisphere and altered the Earth's climate and ecology.

Similar evidence has been found in soil in Europe, Asia, and South America, according to the article (subscription required) published in Science this week. The findings could have an effect on researchers' understanding of the history of the Earth's climate and inhabitants. They also lend credence to beliefs that an object from space could have set off a chain of events that resulted in the sudden extinction of the mammoth, mastodons, and other living creatures in North America.

Researchers plan to study records on climate, archeology, and paleontology for further research. They believe the largest portion of the comet may have landed in the ocean, since no major impression has been found.