David-BurleyDavid Burley and his colleagues applied uranium/thorium dating to a series of coral artifacts including the ones seen here to establish within 16 years the time during which the first settlers arrived in Polynesia.

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Pinpointing Polynesia’s settlement date

November 22, 2012
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SFU archaeologist David Burley and colleagues at the University of Queensland in Australia have narrowed to within 16 years the time during which the last major chapter in human colonization, the Polynesian triangle, occurred.

The scientists say Polynesia’s first settlers—the Lapita people—arrived between 880 and 896 BC, 2,830 to 2,846 years ago. The 16-year settlement window is far smaller than the previous radiocarbon-dated estimate of 178 years, between 2,789 and 2,947 years ago.

Burley and his colleagues published their claims Nov. 7 in an article in the open-access journal PLoSONE.

Polynesia, a group of 1,000 islands forming a geographic triangle connecting Hawaii, New Zealand and Easter Island in the South Pacific Ocean, is one of the last areas discovered and settled by humans.

Burley’s team applied uranium/thorium dating to a series of coral artifacts recovered from a site in Tonga known to be the first Polynesian settlement location.

The dating technique is not new, having been used previously to date coral reefs and stalagmites in caves and other materials. But Burley’s team had to develop new processes and verification protocols to achieve their more precise dating of the Tongan artifacts.

When the scientists results came back from the lab, Burley says his only comment was: “Wow! It is spooky that we can track an event that happened so long ago to such an exact period of time.”

The researchers dated coral files, artifacts used to file-down wood or shell materials for manufacturing other artifacts. They successfully date 13 files ranging in temporal sequence from the top to the bottom of their archaeological site.

Burley is most excited about a coral file found at the bottom. Not only does it have the oldest date, but it was also found in beach sand over which the archaeological site formed.

“It is the beach on which first landfall took place,” says Burley. “And we now know exactly when that happened.”

Read the PLoSONE article at: http://at.sfu.ca/pLoLfF.

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