Wasp nests help to unlock secrets of WA's Aboriginal rock art

We know that there is older art than this in Australia, but it usually has been on plaques and pieces of rock that has fallen off the wall and we don't get the full image. This time we we've got the full picture of what it is.

A yam-like motif painted in mulberry coloured ochre on the ceiling of a deep cavern
(Image: ABC Kimberley)

Leah McLennan and Vanessa Mills ABC Kimberley 1 September 2016

Researchers have used wasp nests that are thousands of years old to date Aboriginal paintings in Western Australia's remote north-west Kimberley region.

After a three-year-long project, archaeologists have dated what they say "may be the longest, most impressive rock art sequence anywhere in the world".

The collaborative Australian Research Council project involved researchers from the University of New England, Macquarie University and the University of Wollongong, and 20 Aboriginal community members from Kandiwal and Kalumburu.

The Kimberley has tens of thousands of rock art sites, including those in the rugged Lawley and Mitchell river basins.

(Image: UNE - ABC Kimberley)

The group focused on the Mitchell Plateau and the area around the Lawley River, home to some of the most remote and rugged country in Australia.

Lead author and archaeologist from the University of New England, Dr June Ross, said results from dating the wasp nests overlying the artworks confirmed the origin of the rock art was "indeed ancient".

She said it provided evidence that the art was painted just after the height of the last ice age.

"Our results demonstrate that at least some phases of Kimberley art are of great antiquity," she said.

Among the team's discoveries was a "perfectly preserved yam-like motif painted in mulberry coloured ochre on the ceiling of a deep cavern".

It has a minimum age estimate of more than 16,000 years.

"We know it was painted before 16,000 years ago, so we are very excited about that," Dr Ross said.

"We know that there is older art than that in Australia, but it usually has been on plaques and pieces of rock that has fallen off the wall and we don't get the full image. This time we we've got the full picture of what it is."

Wunambal Gaambera Aboriginal Corporation chair Cathy Goonack said rock art in the Mitchell Plateau area attracted visitors from around Australia and the world, and the new research would help inspire locals to care for the art work.

"They want to look at our art and hear our stories. Now we have got a good science story that we can tell people as well," Ms Goonack said.

"We will also use this information to help us look after our art."

Technique dates grains of sand

The researchers used three different dating techniques to investigate the wasp nests that were attached to the rock art sites.

Using a light sensitive method called "optically-stimulated luminescence", which was applied to the sand grains found within mud wasp nests, researchers were able to date when the artwork was created.

The technique measures the period of time since a grain of sand was last exposed to sunlight, thus providing a minimum estimate for the time that the artist could have painted the image.

"Mud wasps really are the most helpful insects," Dr Kira Westaway said, a geochronologist from Macquarie University.

"They build nests on top of the art using grains of sand that can be used for dating without damaging the art itself.

"As long as we understand how the nests are constructed and how well they are preserved over thousands of years, we can use the resulting age to confidently claim that the artist painted this image before the mud wasp constructed its nest."

Establishing firm dates for rock art is notoriously difficult, but dates of around 40,000 years have been recorded for images in Indonesia and Spain.

In Australia dates of between 13,000 to 15,000 years old have been recorded in Queensland, and up to 28,000 years in Arnhem Land in the Northern Territory.