19 April 2013

Rock art may last up to 60,000 years

By
COSMOS Online
The world’s largest collection of rock art engravings could also potentially be home to some of the oldest, Australian researchers have found.
Burrup Peninsula rock art showing two birds. Credit: Brad Pillans / ANU

Burrup Peninsula rock art showing two birds. Credit: Brad Pillans / ANU

SYDNEY: The world’s largest collection of rock art engravings could also potentially be home to  some of the oldest, Australian researchers have found.

In a paper published in the June 2013 issue of Quaternary Science Reviews, scientists estimated that the Burrup Peninsula rock art gallery in Western Australia has the potential for the preservation of engravings up to 60,000 years old.

Geologist Brad Pillans from the Australian National University in Canberra, head researcher for the study, said that this time-scale is “basically a bit longer than we think humans have been in Australia, so there is the potential for the very earliest records of aboriginal rock art to be preserved there.”

Slow erosion

Burrup Peninsula and the islands in the surrounding Dampier Archipelago are home to an estimated one million rock engravings created by Indigenous Australians, including images of water birds, crabs, crayfish, kangaroos and figures with both human and animal features. The importance of this extensive collection of ancient art has been recognised by its inclusion on the National Heritage Register of Australia.

Pillans and his team carefully took rock samples from the Burrup Peninsula and determined that the long-term natural rate of weathering and erosion had been remarkably low, as little as 0.15 millimetres per 1,000 years on some horizontal rock surfaces.

The researchers said this could be attributed to the durability of the rock itself and the dry climate of the Burrup Peninsula. “The combination of very hard rock and very low rainfall means that surface preservation is enhanced in this environment,” said Pillans.

Rock art age still to be determined

Paul Taçon, an archaeologist and rock art expert at Griffith University in Queensland, who was not involved in the study, emphasised that the findings did not necessarily imply  the world’s oldest rock art exists at the Burrup Peninsula, just that it could.

According to Taçon, there is no current evidence to suggest that people were in the Burrup Peninsula area 60,000 years ago. He said the research showed “that certainly the rock surfaces that the engravings have been carved into are very, very tough and they don’t disappear after five or ten thousand years.”

Taçon added that the engravings are unlikely to last as long as the flat rocks themselves “because water and sand would accumulate in them causing increased erosion rates,” and that further research needs to be conducted to determine the exact age of the rock art.

Pillans said that a major obstacle would be that rock art is notoriously difficult to date. “You have to appreciate that these engravings are cut into the rock surface so, unlike paintings, we cannot date say, charcoal or organic materials in pigment on the rock,” he said.

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