“All our stories are written on these stones,” says Corey Adams, a traditional Aboriginal custodian of the Murujuga land we are standing on in Western Australia. He is showing me around the densest collection of ancient rock art in the world – more than 2 million engravings, or petroglyphs, that his ancestors have created since becoming the first people to set foot in Australia.
The collection has been added to for more than 50,000 years, making it the most continuous sequence of rock art in the world. It is also among the oldest, coming close to Spain’s record-breaking 66,700-year-old cave paintings.
Murujuga, which means “hip bone sticking out” in the local Ngarluma-Yaburara Aboriginal language, refers to a peninsula jutting out of the remote Pilbara region. It also includes surrounding islands that were connected to the mainland until about 7000 years ago, when they were cut off by a 130-metre sea level rise that began after the last glacial maximum.
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I have come here to join an archaeological and geological expedition by researchers from the University of Western Australia and the University of Wollongong in New South Wales. They are seeking to precisely date the rock art and understand more about how its surrounding environment has changed.
Current estimates of the art’s age, at about 50,000 years old, are based on the dating of stone tools and other human artefacts found in a nearby cave. Only now is the art itself being directly dated.
To get here, we took a helicopter from Karratha, a nearby mining town. It was blowing a gale when we arrived at the airport and I was nervous about my first-ever helicopter ride. However, our pilot said I shouldn’t panic unless I see him pull his visor down to mask the fear in his eyes, which was reassuring.
Thankfully, we landed in one piece on a northern island of Murujuga called Middle Gidley. The landscape is spectacular in a parse, rugged way. There are no trees, just spiky spinifex grass interspersed with large jumbles of rocks that change from orange to red to pink to purple as the sun moves across the sky. I can see how this scenery has inspired
a torrent of human creativity.
There is art all over the rocks – images of people dancing, boomerangs, boats, wallabies, emus and extinct species like fat-tailed kangaroos and thylacines, or Tasmanian tigers. The newer art captures whales, fish, crabs and turtles that arrived when rising sea levels turned the once-inland region into a coastal area.
The unusual hardness and low weathering rates of the rocks have exquisitely preserved the drawings, made by scratching or carving the surface with sharpened stones.
Luke Gliganic at the University of Wollongong is trying to date the art using a technique called optically stimulated luminescence surface exposure dating. The idea is to measure the rate at which freshly exposed surfaces of the rocks at Murujuga – like those formed during carving – lose electrons, which occurs upon light exposure. The age of the ancient carvings can then be extrapolated by measuring their electron loss to date.
We hop back on the helicopter to fly to nearby Rosemary Island, where Gliganic has been given permission from traditional owners to make an experimental carving on one of the rocks. He uses a drill, hammer and chisel to cut small cores out of the rock surface. To limit light exposure, he then quickly wraps them in foil to take to his lab. Gliganic will collect more of these samples during future trips to establish the rate of electron loss across a given time period.
Back on Middle Gidley, Matthias Leopold, Caroline Mather, Mick O’Leary and Diego da Silva Turollo, all at the University of Western Australia, are working on a way to try to reconstruct historical climate records for Murujuga. Normally, these are reconstructed by studying tree rings, ice cores or stalagmites and stalactites in caves, but the sparse landscape of Murujuga offers none of these things, so the researchers have had to get creative.
They previously found a shallow basin in Middle Gidley that contains layers of sediment that have built up over time. These layers may hold clues to past environmental conditions and, with any luck, could contain ancient stone tools that can be dated based on their depth. Traces of pollen may also indicate changes in vegetation.
The researchers fire up a large drill, which they use to drive metal tubes into the ground and extract 10-metre-long cores. It is back-breaking work, especially with the blazing sun overhead and no trees to provide shelter. Once the cores are ready, they are carried back to the mainland in a large net swinging below a helicopter. There, they will be transported by truck 1500 kilometres to the University of Western Australia for analysis.
Exhausted and streaked with red dirt, we finally set up camp as the sun starts to dip below the rocks. Lying in my tent, I think about the first people who arrived here, who had to pull off one of humankind’s first-ever open water crossings to get to Australia, from somewhere in south-east Asia. After travelling down the coast, they chose this spot to begin capturing their stories.
Their enduring art has allowed them to continuously pass on their ancient wisdom and traditions, with Murujuga people today still performing some of the dances and rituals illustrated on the rocks.
Unfortunately, there is uncertainty about how long the art will last. Some scientists and traditional owners believe that emissions from a nearby liquefied natural gas processing plant may be damaging the rock art, although others have found no evidence of this. The government of Western Australia has partnered with the Murujuga Aboriginal Corporation to research whether the rock art is being damaged, but the results aren’t expected for years.
Certainly, everything should be done to protect this special place. There is nowhere else on Earth where you can peer so clearly into a 50,000-year-long story of humanity, spanning massive climate shifts, dramatic sea level rises and changes in flora and fauna. As Adams says: “It’s not only significant to Aboriginal culture, it’s [significant to] the whole world.”
