Sediment samples and Optically Stimulated Luminescence help determine age of jars of one of South East Asia’s most important archaeological sites.

Sediment samples from beneath stone jars from two of the more than 120 recorded megalithic sites were obtained by a team led Dr Louise Shewan from the University of Melbourne, Associate Professor Dougald O’Reilly from the Australian National University (ANU) and Dr Thonglith Luangkoth from the Lao Department of Heritage.

The samples were analysed using a technique called Optically Stimulated Luminescence (OSL) to determine when sediment grains were last exposed to sunlight.

«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,» Dr Shewan said.

The megalithic jar sites in Northern Laos comprise one to three-metre-tall carved stone jars, weighing up to 20 tonnes, dotted across the landscape, appearing alone or in groups of up to several hundred.

Dr Shewan and her team completed their most recent excavations in March 2020, revisiting Site 1 (Ban Hai Hin), and arriving back in Australia just before global pandemic international boarder closures.

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