Archaeologists have been mapping a hidden landscape where the first Australians emerged over 60,000 years ago. This region was once a coastal mangrove swamp, but before that, it was a semi-arid savannah plain that was hundreds of kilometers from the sea. During the late Pleistocene epoch, Australia was connected to its northern neighbors, New Guinea and Indonesia, in a supercontinent known as Sahul. Then, at the end of the last ice age, around 10,000 years ago, large areas of land were submerged as ice sheets melted.
Australia’s First Peoples occupied these parts of northern Australia for at least 65,000 years, as indicated by thousands of stone tools and remnants of food scraps unearthed at the Madjedbebe rock shelter in the 2010s. Their presence indicates a remarkable journey of skilled mariners traversing seas and land bridges to inhabit the driest continent on Earth. To help with the search for other ancient sites, researchers working with the local Njanjma Rangers reconstructed an ancient landscape buried beneath today's seasonal floodplain. Their efforts could redirect the search for these ancient sites occupied by Australia's first peoples by mapping the long-forgotten landscape that greeted those people when they arrived. The team used geophysical measurements to digitally 'peel back' layers of soil and expose a string of sandstone cliffs that "for the majority of human occupation were actually exposed and probably habited by people," according to Flinders University archaeologist Jarrad Kowlessar.
This technique is electrical resistivity tomography, which involves passing an electrical current through the ground to measure sediments and rocks below. Comparing those results with aerial mapping, the team came to appreciate just how much the landscape has changed. A deep valley and river system are now buried under more than 15 meters of sediments deposited by extensive mangroves. The researchers say it could contain sites where Australia's first people left behind rock art or stone tools. However, it remains to be seen if those artifacts have been preserved. Visualizing these landscapes and understanding the rapid environmental change Australia's Indigenous peoples witnessed at Red Lilly Lagoon will guide interpretations of existing rock art sites that depict fish, crocodiles, and marine life. This research reveals a complex Pleistocene landscape, offering the potential to locate additional archaeological sites and reveal more about the lifeways of the earliest Australians, according to Kowlessar and colleagues in their published paper.
As every year passes, research enriches the oral histories of Australia's Indigenous peoples, and we come to understand more about the country's deep past. Protecting these areas steeped in history has become an urgent issue. Rock art sites on Western Australia's Burrup Peninsula are being removed and damaged by the expansion of heavy industry. Once these sites are destroyed, our chance to see the land through the hands and eyes of ancient peoples is lost, save for the stories their descendants share.