Nano-Diamonds and Clovis Sites

A brief paper published in Science on January 2, 2009, revealed data supporting an hypothesis about the abrupt end of the Clovis culture which was originally reported in 2007, and now has growing support among the scientific community.

Air Bombs

Cretaceous Period Chicxulub Crater, seen as a pale circle taking up a huge hunk of the Yucatan Peninsula, Mexico. This is what an impact crater looks like--there is no evidence that such a crater is associated with the black mats and nanodiamonds
Photo Credit: NASA / Getty Images

The theory goes that an asteroid or asteroids either exploded in air above North America or landed on the Laurentide Ice Sheet which covered Canada about 10,900 RCYBP (calibrated to 12,900 years ago). Those explosions—I notice the Science paper doesn't talk about the ice sheet—triggered environmental changes called the Younger Dryas (YD). The unarguable effects of those changes include the disappearance of large-bodied animals like mammoths and mastodons (called collectively megafauna) and the disappearance of the Clovis culture, a human population who survived by hunting those megafauna. It's likely that the Clovis people themselves (or at least some of them) survived--they just changed to hunting smaller animals and collecting plants, called the "Archaic" period in the Americas.

The physical evidence for this catastrophe, say scientists, is a "black mat" covering several Clovis sites. A black mat is a thin, organic-rich layer of sediment, characterized by lots and lots of carbon and the presence of nano-diamonds. Black mats were first recognized at Clovis-period archaeological sites by C. Vance Haynes in the 1970s. Haynes tied the black mat to a climate shift, but didn't make the leap to asteroid impacts.

Nano Diamonds and Destruction

Enormous Cubic Diamond, Frankie B Fashion Show; not what you'll find in a black mat (or on the ring finger of any archaeologist, I daresay)
Photo Credit: Frazer Harrison / Getty Images

Nano-diamonds (or nano-sized diamonds) are thought to have been created out of the carbon by exposure to shock. Cubic diamonds—the kind you buy from the jewelry store—form under high temperatures and pressures, temperatures that surely would have killed everything and everybody; nano-diamonds formed under a lesser shock.

Researchers opined in 2007 that the occurrence of the nano-diamonds in the black mat is evidence of explosions in air, or an impact of an asteroid on top of the glaciers which covered Canada at the time. If there had been a full cometary explosion, the evidence would have included shocked minerals and impact craters, and those kinds of things, seen at crater sites like Chicxulub in Yucatan, are not found in North America dated to the appropriate time.

Science 2009

The latest paper is a peer-reviewed version of the earlier PNAS paper. It reports evidence of an abundance of nano-diamonds at the onset of the YD at Murray Springs, Arizona; Bull Creek, Oklahoma; Gainey, Michigan; Topper, South Carolina; Chobot, Alberta; and Lake Hind, Manitoba.

More on Black Mats, Nano-Diamonds and Clovis

• Clovis, Black Mats, and Extra-Terrestrials, lots more detail on the PNAS paper
• Who Were the Clovis People?
• The Megafaunal Extinctions

Academic Sources

• Firestone, R. B., et al. 2007 Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling. Proceedings of the National Academy of Sciences 104(41):16016-16021. Free download
• Haynes Jr., C. V. 1991 Geoarchaeological and Paleohydrological Evidence for a Clovis-Age Drought in North America and Its Bearing on Extinction. Quaternary Research 35:438-450.
• Haynes, Jr C. V. 2008 Younger Dryas "black mats" and the Rancholabrean termination in North America. Proceedings of the National Academy of Sciences 105(18):6520–6525.
• Kennett, D. J., et al. 2009 Nanodiamonds in the Younger Dryas Boundary Sediment Layer. Science 323:94.
• Quade, Jay, Richard M. Forester, William L. Pratt, and Claire Carter 1998 Black Mats, Spring-Fed Streams, and Late-Glacial-Age Recharge in the Southern Great Basin. Quaternary Research 49(2):129-148.

Recent News Stories and Blogs

• Discover Magazine: Nano-Diamond Discovery Suggests a Comet Impact Killed the Mammoths January 5, 2009
• Nature Blog: Did killer comets bring the bling? January 5, 2009
• Science Daily: Six North American Sites Hold 12,900-year-old Nanodiamond-rich Soil January 2, 2009
• University of Oregon PR: Six North American sites hold 12,900-year-old nanodiamond-rich soil
• BoingBoing: Devastating comet hit North America 13,000 years ago? January 2, 2009