Archaeologists and traditional owners have visualised an ancient landscape hidden under an inland West Arnhem flood plain for thousands of years, using a technique they say could guide future archaeological digs.
The Red Lily Lagoon flood plain sits more than 40 kilometres inland, near a culturally significant rock art site, Madjedbebe.
Archaeologists have long believed that the landscape has changed from semi-arid, to coastal, to the modern-day flood plain, as ocean levels changed over thousands of years.
Around 6,000 to 9,000 years ago, researchers believe the ocean extended much further inland, and the Red Lily Lagoon area was a coastal region.
A team from Flinders University, working with senior traditional owner Alfred Nayinggull and local Njanjma rangers, has now used drones, laser and subsurface imaging techniques to look below the present-day flood plain, revealing a coastal landscape now buried under layers of sediment.
The researchers used a 3D model to visualise that landscape, with the findings, published in scientific journal Plos One on Friday.
"These results show that there were huge sandstone escarpments — similar to the dramatic sandstone escarpments we see in Arnhem Land and Kakadu today — that are completely under the ground now from all the sediment that this marine seawater would have brought with it, that for the majority of human occupation was actually exposed and probably habited by people," lead researcher Jarrad Kowlessar said.
He said the underground mapping and visualisation technique could be used by archaeologists to identify underground sites where First Australians may have lived thousands of years ago and potentially left behind rock art or tools.
"If we can use this method to map these sandstone cliffs, and we can use this method to look at whether there are any [rock art] painting preservations," he said.
"The data is one thing, but to then visualise it, model it in 3D and be able to explore those environments means that we can understand the data in new ways and understand what life might have been like," Dr Kowlessar said.
New 3D mapping technology 'promising' for archaeology
The study's co-author, Associate Professor Ian Moffat, said the technique was a "game changer" for archaeological research.
"Instead of focusing on the archaeological sites — which is the way we normally think about archaeology — we've really stepped out and tried to understand the landscape in a much more holistic way," he said.
Dr Moffat said his long-time collaborator, senior traditional owner Alfred Nayinggull had been a driving force behind the work.
"He is very passionate about asking these questions about the landscape and about protecting and understanding the incredible rock art and archaeological record of the Red Lily lagoon area."
Professor Paul Tacon, an archaeologist at Griffith University who was not involved in the research, said the technique was a "promising" use of the 3D modelling technology, but more research was needed.
"There needs to be some sort of follow up research to see if it is indeed evidence of Pleistocene habitation sites where they have suggested they may be located."
He also warned that if rock art had been painted on the sandstone cliffs, it would likely have been eroded by now.
"Unfortunately if the rock art had been made at the habitation site there wouldn't be much of it left because of the acidic soils and the amount of time it has been buried, all of which would have eroded painted art away."
But Dr Kowlessar said even if rock art had been destroyed over time, the technique could be used to help find sites where humans may have left behind tools, helping to deepen researchers' understanding of Australia's First Peoples.
"These insights present completely new challenges to archaeological research. It gives us a new direction to look in."
