Tiny Gems, Cosmic Impact

Diamonds Found on Santa Rosa Island

Hexagonal nanodiamonds discovered on Santa Rosa Island

Nano-sized diamonds found embedded in the crust of Santa Rosa Island off the coast of Santa Barbara appear to have been formed when a comet crashed into Earth-the same comet that scientists say may also be responsible for the extinction of the island’s pygmy mammoth. “The pygmy mammoth, the tiny island version of the North American mammoth, died off at this time,” said UCSB professor emeritus James Kennett, who, with his son Douglas Kennett of the University of Oregon, led the 15-person research team whose findings were published this week in the Proceedings of the National Academy of Science (PNAS). “Since it coincides with this event, we suggest it is related,” Kennett said.

The diamonds’ creation also coincides with the disappearance of the first well established and distributed North American people, known as the Clovis. Nineteen types of birds and 35 species of mammals vanished in the same time frame.

Douglas Kennett said the hexagonal diamonds known as lonsdaleite are typically found in meteorites and impact craters; those in the sedimentary layer covering Santa Rosa Island known as Younger Dryas Boundary are evidence that a cataclysmic impact approximately 12,900 years ago scattered comet fragments across North America. James Kennett said that the diamonds’ unique “assemblage of material” would not be possible without a long-ago cosmic blast.

Dark layer of sediment is exposed in Arlington Canyon on Santa Rosa Island.

The Santa Rosa diamonds were found under four meters of millenniums-old dust and soot telling a dark tale indeed. This layer was once airborne, the scientists hypothesize, sent skyward by the landing of the comet fragments-fragments that impacted with enough speed, heat, and force to produce not only dust, soot, and diamonds but extensive wildfires. Not enough sunlight could penetrate to enable the species’ survival. “This hypothesis fits with the abrupt climatic cooling as recorded in ocean-drilled sediments beneath the Santa Barbara Channel,” Kennett said.

Many of his peers consider James Kennett, former director of the Marine Science Institute at UCSB and native New Zealander, the “father” of marine geology and paleoceanography.

Douglas Kennett received his bachelor’s, master’s, and PhD in anthropology at UCSB.

Funding for the research was provided by the National Science Foundation.

Co-authors on the PNAS paper are Jon M. Erlandson and Brendan J. Culleton, of the University of Oregon; Allen West of GeoScience Consulting in Arizona; G. James West of UC Davis; Ted E. Bunch and James H. Wittke, of Northern Arizona University; Shane S. Que Hee of UCLA; John R. Johnson of the Santa Barbara Museum of Natural History; Chris Mercer of UCSB and National Institute of Materials Science in Japan; Feng Shen of the FEI Company; Thomas W. Stafford of Stafford Research Inc. of Colorado; Wendy S. Wolbach and Adrienne Stich, of DePaul University in Chicago; and James C. Weaver of UC Riverside.


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