A continent “unlike anything found today” that was home to half a million people has been discovered off the northern coast of Australia.
The now-submerged continental shelf is a vast, habitable landscape that existed for 65,000 years and covers approximately 390,000 km2 – an area even larger than New Zealand.
A Continent with Complex Landscapes
Scientists, led by Kasih Norman from Griffith University (Queensland), have made a groundbreaking discovery. They state that this “complex landscape” on the Northern Shelf of Australia “is unlike any landscape found on our continent today.”
The now-submerged continental shelf was habitable for 65,000 years – (Image: Ladbible).
Additionally, the languages and rock art styles of the inhabitants here are similar to those of nearby groups. These areas were once connected by the continental shelf, which still exists – the Arnhem Land region to the north and Kimberley to the northwest.
Norman and her colleagues explain that when the last Ice Age ended around 18,000 years ago, global warming caused sea levels to rise, submerging many landmasses around the world.
This phenomenon divided the supercontinent Sahul into New Guinea and Australia, while also cutting Tasmania off from the mainland. The now-submerged continental shelves of Australia are believed to be environmentally unproductive and largely overlooked by the indigenous communities.
“However, increasing archaeological evidence suggests that this assumption is incorrect. Many large islands off the coast of Australia – which once formed part of the continental shelf – show signs of being inhabited before sea levels rose,” the researchers write.
Before Norman and her team conducted their investigations, archaeologists could only speculate about the nature of these submerged landscapes, dating back to before the last Ice Age, as well as their population sizes.
But the newly published findings have added many missing details, revealing that the Northern Shelf was a lush domain, with islands, lakes, rivers, and even vast inland seas. “This area contained habitable freshwater and saltwater environments. The most notable feature among these is the Malita inland sea,” they noted.
Ancient History of Ups and Downs
According to archaeologists, this marine area existed for 10,000 years, from 27,000 to 17,000 years ago, with a surface area larger than 18,000 km2. The Northern Shelf may have been home to between 50,000 and 500,000 inhabitants at various times over the past 65,000 years, according to a model created by Norman and her team.
The population likely peaked during the last Ice Age, about 20,000 years ago, when the entire continental shelf was dry land.
To draw their conclusions, researchers projected past sea levels onto high-resolution maps of the ocean floor.
They discovered that low sea levels revealed a vast archipelago of islands on the Northwestern Shelf of Sahul, extending 500 km towards Indonesia’s Timor Island. This archipelago appeared around 70,000 to 61,000 years ago and remained stable for about 9,000 years.
“Thanks to the rich ecosystems of these islands, people may have migrated in stages from Indonesia to Australia, using this archipelago as stepping stones. As the last Ice Age approached, ice caps at the poles increased and sea levels dropped by up to 120 meters. This exposed the entire shelf for the first time in 100,000 years,” scientists noted.
However, by the end of this Ice Age, rising sea levels submerged the continental shelf, forcing residents to flee as water encroached upon the once fertile land.
“The retreating population would have been forced to regroup as available land shrank,” the experts write, noting that this led to the emergence of “new rock art styles” in both Kimberley and Arnhem regions.
