A 26-member multi-institutional team led by the University of Oregon has discovered a nanodiamond-rich soil layer at six different sites across the North American continent.Nanodiamonds (nanometer-sized gems) are produced under high-temperature, high-pressure conditions, which occur rarely in nature. The presence of this nanodiamond formation supports the theory of a scattered comet impact about 12,900 years ago.
The nanodiamonds were found only in what is called the Younger Dryas Boundary, a geologic strata dated at about 12,900 years ago. Below this boundary layer are a wealth of prehistoric fossils from now-extinct species, including artifacts from the prehistoric Clovis culture. This strata also marks the beginning of a 1300-year cold period known as the Younger Dryas. A series of clustered comet impacts may have been responsible for this extinction event.
The sites are identified as Murray Springs, Arizona; Bull Creek, Oklahoma; Gainey, Michigan; Topper, South Carolina; Lake Hind, Manitoba; and Chobot, Alberta.
These results are reported in the January 2nd issue of Science.
Photo: ScienceDaily
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