Scientists use sub-surface imaging to uncover ancient landscape changes in Northern Australia’s Red Lily Lagoon and its impact on rock art

Researchers at Flinders University have made a groundbreaking discovery about the Red Lily Lagoon area in Northern Australia using sub-surface imaging and aerial surveys. The methods allowed them to see through floodplains and determine how the landscape was affected when sea levels rose around 8,000 years ago. The researchers found that the ocean had reached this now-inland region, which has significant implications for understanding the archaeological record of Madjedbebe, the oldest archaeological site in Australia. The findings also shed new light on the rock art in the area, which is globally recognized for its significance and unique style.

The researchers were able to examine how sediments buried beneath the floodplains changed as sea levels rose, revealing how the transformation of Red Lily Lagoon resulted in the growth of mangroves that supported animal and marine life in the region. The environment fostered by this transformation inspired the subjects and animals in the ancient rock art.

According to Dr. Jarrad Knowlessar, Senior Author and Research Associate at Flinders University, the mapping of the area fundamentally changes our understanding of the landscape in Arnhem Land, which is a key landscape for understanding the early human occupation of Australia. He added that their reconstruction of Red Lily Lagoon enables predictive modeling of prominent cultural sites and provides an important method for interpreting the presence and provenance of Indigenous cultural material. The researchers also found that changes in the rock art’s subject matter reflected the broader environmental changes that took place in the landscape, such as the appearance of estuarine animal species like fish and crocodiles, which occurred when freshwater floodplains made up the landscape.

The study’s results indicate that all Pleistocene sites in western Arnhem Land were once located near the ocean and, subsequently, mangrove swamps during the landscape’s transformation. This finding is significant for understanding the paleogeographic settings of these sites and interpreting changes in stone artefacts, food resources, and isotope composition from this period of the first Australians.

Co-author Associate Professor Ian Moffat explains that Electric Resistivity Tomography (ERT) is a non-invasive, rapid, and cost-effective method that can map large areas of the Australian landscape, providing insight into their ancient history. The study demonstrates the usefulness of ERT data in developing landscape models that can help identify buried archaeological sites and improve our understanding of the regional geography and its impact on past human behavior. These findings have important implications for locating new sites and gaining a more nuanced understanding of the region’s history.

Red Lily Lagoon Modern Day Visualisation 2. Credit: Dr Jarrad Knowlessar, Flinders University Research Associate
Red Lily Lagoon Pleistocene (Ice age) 9,000 years ago visualisation. Credit: Dr Jarrad Knowlessar, Flinders University Research Associate.
Red Lily Lagoon Pleistocene (Ice age) 9,000 years ago visualisation 2. Credit: Dr Jarrad Knowlessar, Flinders University Research Associate.
Sea level flooding – Mangroves Image. Credit: Dr Jarrad Knowlessar, Flinders University Research Associate.
Sea level flooding at Red Lily Lagoon area. Credit: Dr Jarrad Knowlessar, Flinders University Research Associate.
Sea level flooding 2. Credit: Dr Jarrad Knowlessar, Research Associate at Flinders University.

Red Lily Lagoon holds great archaeological significance in Arnhem Land, as it is located at one of the easternmost points of the East Alligator River floodplain. This area is significant as the Arnhem Plateau creates a significant boundary between the low-lying floodplains and the sandstone highlands, which have been occupied by humans for over 60,000 years and are home to numerous significant sites, including some of the most renowned rock art panels in Australia.

Co-author and traditional owner, Alfred Nayinggull, emphasized the importance of this research, stating that they want to share the knowledge of what happened thousands of years ago with others.

Source: Flinders University

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