Rising sea levels have obscured large swaths of the land people once called home.. Now scientists have found evidence of a lost continent off the northern coast of Australia, where half a million people lived about 70,000 years ago.

This land mass, known as the Northwest Platform, It was about 1.6 times larger than Great Britain and contained archipelagos, lakes, rivers and a large inland sea. The archipelagos were so large they could have acted as a migration route from Indonesia to Australia, experts say.

Unfortunately, the northwest platform It was lost about 10,000 years ago when sea levels rose and now lies about 90 meters underwater in the Timor Sea. The new study was led by Kasih Norman, an archaeologist at Griffith University in Queensland. “We have revealed details of the complex landscape that existed on Australia’s northwest shelf,” said Norman and his colleagues.

“It was unlike any landscape you find on our continent today.” The last ice age ended about 18,000 years ago. The subsequent warming caused sea levels to rise and flood large parts of the world’s continents, including a huge landmass surrounding Australia.

This landmass connected the Australian continent to New Guinea and Tasmania (now known collectively as Sahul), but as sea levels rose, parts of it became submerged. This process divided the Sahul supercontinent into New Guinea and Australia, and isolated Tasmania from the mainland.

The northwest platform of Sahul was especially so a “vast, habitable kingdom” and a “unique cultural zone” with similarities in stone ax technology, rock art styles and languages, experts say. For the study, they analyzed bathymetric data (information about the depths and shapes of underwater terrain) in the northwestern shelf area. They also analyzed historical sea level data to help estimate when the region was populated and when it was lost.

Rapid global sea level rise between 14,500 and 14,100 years ago and 12,000 to 9,000 years ago caused the rapid flooding of about half of the northwestern shelf with seawater. The human population would have witnessed a ‘coastal invasion’ and retreated further towards the Australian continent.

This resulted in an increase in population in the Kimberley and Arnhem regions of Northern Australia, evidenced by distinctive new styles of rock art in both regions. The team also pointed to stone tools recently found on the seabed off the coast of Western Australia’s Pilbara region.

The study was published in Quaternary Science Reviews. (JO)