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Geologic tests shed light on the age of megalithic jars


Australian researchers have uncovered the age of the mysteriously noted megalithic jars in Laos.

Doctor Louise Shewan of the University of Melbourne, along with Associate Professor Dougald O’Reilly of the Australian National University, and Dr Thonglith Luangkoth from the Laos Department of Heritage used a sampling technique called optically stimulated luminescence.

The technique analysed how long the sediment from beneath the jars had gone without any sunlight and determined the jars to have been put in place anywhere between 1240 and 660 BCE.

Shewan said the latest findings uncovered much new information in the context of the jars’ existence.

“With these new data and radiocarbon dates obtained for skeletal material and charcoal from other burial contexts, we now know that these sites have maintained enduring ritual significance from the period of their initial jar placement into historic times,” Shewan said.

Using another geological dating technique, the researchers determined the location of the jars for at least one site, tracking it to a presumed quarry about eight kilometres away.

“How the jars were moved from the quarry to the site, however, remains a mystery,” O’Reilly said.

The jars were added to the UNESCO World Heritage List in July 2019, as the UNESCO committee declared the site “the most prominent evidence of the Iron Age civilisation that made and used [the jars] until it disappeared”.

Shewan said the next big undertaking for her team is gathering more samples from similar sites. The challenge is not in finding the samples but in the fact Laos is said to be the most heavily bombed country, per capita in the world, following the Vietnam War.

Reportedly, less than 10 per cent of the megalithic jar sites have been cleared for research and pose no risk of unexploded bombs.

“We expect that this complex process will eventually help us share more insights into what is one of Southeast Asia’s most mysterious archaeological cultures,” Shewan said.

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