A drone shooting laser light beams that can “disappear” dense bush to reveal what lies beneath has located three new Aboriginal rock shelters within a minuscule part of the Greater Blue Mountains’ world heritage site’s 1.03 million hectares.
The discoveries by the University of Sydney’s digital archaeologist Dr Jacob Bongers have raised hopes that hundreds – maybe thousands – of ancient sites could be identified across the vast UNESCO site, which is about the same size as Lebanon.
The drone used light detection and ranging (LiDAR) technology to create a 3D map of the terrain that is accurate down to centimetres. “What’s great about LiDAR’s lasers is that you can remove the tree canopy and see what’s underneath, allowing us to find shelters deep in the bush,” Bongers said.
The newly located sites, some with red hand stencils and stone artefacts, show signs of continuous Indigenous occupation going back millennia.
Wayne Brennan, a Gomeroi man, rock cave expert and archaeologist from the university, said he was blown away when he first saw it: “I couldn’t believe it. I thought it was whitefella magic.”
Brennan said LiDAR would help identify undisturbed rock art and cultural sites that could bolster the case to extend the Blue Mountains’ UNESCO listing to include its Indigenous culture.
“The main trump card we’ve got is that this is undisturbed landscape with cultural heritage in it, and that doesn’t exist in many places in the world. That’s our punchline … our right hook.”
Its existing listing recognises its biodiversity, including its exceptional eucalyptus landscape, and its prehistoric species, such as the Wollemi pine, against a backdrop of 300-metre sandstone cliffs.
The research project is called Gulumada, meaning “place of koalas”. It is also the proposed dual language name for the mountains. Explorer George Bass described the Blue Mountains as the “horrible perpendicular mountains” and predicted others would find it impossible to cross.
Yet for thousands of years Indigenous peoples traversed the mountains, stopping for cultural business and staying overnight in shelters.
Because of its difficult terrain, which is close to impassable by foot, only 10 per cent of the entire Blue Mountains has been surveyed, with 200 Indigenous rock shelters recorded containing cultural and archaeological evidence.
The researchers analysed the LiDAR data, generated detections of potential rock shelters and then verified (or “ground-truthed”) these results by walking through the rugged terrain.
They found three unrecorded sites within a 4.16-square-kilometre area.
Using the new technology, a shelter “popped right off the model”, said Bongers.
Within seconds of arriving at the site, Bongers and the University of Sydney research archeologist Dr Amy Mosig Way spotted multiple flaked stone artefacts made of tuff (tuffaceous sandstone) in the sandy floor.
It was evidence of tool marking, said Way, who also works with the Australian Museum. “You only have to look for a second and you can see multiple artefacts.”
Even within the small pilot project site, about 10 per cent of the GBM heritage listed area, the new technology would likely add 30 to 50 rock shelters, many with cultural material, Way said.
A research paper published this week in the journal Remote Sensing by Bongers, with co-authors Brennan, Way and Erin Wilkins, said the results proved the technology can locate unregistered archaeological rock shelters within, and beyond, Australia.
“The Blue Mountains was a test case. We did the research here, the data is from here, but it is bigger than Australia. This approach could be used in any other rugged environment or challenging terrain,” Bongers said.
Bongers is among a new wave of digital archaeologists using drones to do research in areas humans find difficult to access. In Peru he “drone-mapped” more than 5200 precisely aligned holes in the Andes – known as the Band of Holes – to discover it was a kind of Indigenous marketplace.
The unregistered rock shelters were not listed in any online databases. “The implications here are huge. This methodology can become a tool that Aboriginal communities can use with existing knowledge to locate other sites in rugged environments.”
To show why identifying and protecting these sites was important, Way, Bongers and Brennan visited a known cultural site where bushfire had erased rock carvings like Bic’s Wite-Out blanks text.
“All this white stuff is what fire can do,” Brennan said.
The area spared included engravings of an emu, and a kangaroo that had been speared twice, part of stories that connect sites across the ranges.
Brennan said it was important to get the best possible record we can at this particular moment “because the fire can destroy it. Imagine that.”
Way, Brennan and members of the Dharug Custodian Aboriginal Corporation “ground-truthed” the detections by walking to the site to make an archaeological survey.
Way said, “One of the main issues we had initially had [was] that it would find caves that are on cliff faces. So, yes, it is a rock shelter but there’s no way a human could ever have got into it.”
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