Lost Landmass With Inland Water Discovered in Northwestern Australia; Ancient Colony Was Once Home to 500,000 People

Northwestern Australia is a region known for its arid landscapes and vast deserts. This area is home to three large deserts: the Great Sandy Desert, the Great Victoria Desert, and the Gibson Desert. A recent study, however, reveals this part of the continent was once home to a thriving civilization that existed thousands of years ago. The currently dry and barren land was once covered by an inland sea, providing a unique environment for early settlers.

(Photo: Wikimedia Commons/ NASA/EarthKAM)

Australian Geography

Around 18,000 years ago, the last ice age ended, causing a rise in sea levels, which drowned vast areas of the world's continents. The process split the supercontinent of Sahul into Australia and New Guinea and separated Tasmania from the mainland.

For much of the 65,000 years of human history, the Kimberley and western Arnhem Land were connected by the northwest continental shelf, which is currently submerged. This vast, habitable region covered almost 150,000 square miles (390,000 square kilometers), one-and-a-half times larger than modern New Zealand. Kimberley and Arnhem Land were likely a single cultural zone with similar languages, rock art styles, and stone-axe technology.

Unlike the rest of the world, the continental shelves of Australia, which are currently drowned, were thought to be environmentally unproductive and of little use to First Nations settlers. However, many large islands off the coast of Australia show signs of occupation before rising sea levels.

Lost Ancient Colony

In a recent study, scientists reveal details of the complex landscape in the Northwest Shelf of Australia, with landscape features unlike any other continent. Their discoveries are discussed in the paper: "Sea level rise drowned a vast habitable area of northwestern Australia, driving long-term cultural change."

Archeologist Kasih Norman and her colleagues reconstructed the topography of the Northwest Shelf by mapping sea levels onto high-resolution ocean floor maps. Low sea levels exposed a huge archipelago of islands on the Northwest Shelf of Sahul, which extends 311 miles (500 kilometers) towards the Indonesian island of Timor.

The archipelago appeared between 70,000 and 61,000 years ago and remained stable for about 9,000 years. It might have also been a stepping stone for people who migrated from Indonesia to Australia.

The mapping result also revealed that the Northwest Shelf contained a large lake during the last ice age. At its maximum extent, the lake would have been half the size of Lake Eyre. Several ancient river channels, which would have flowed into the Malita Sea and the lake, are still visible on the ocean floor maps.

The now-drowned shelf could have supported between 50,000 and 500,000 people over the last 65,000 years. This population would have peaked about 20,000 years ago when the entire region was dry. The people were compelled to fall back as the rising sea levels drowned the Northwest Shelf at the end of the last ice age.