Weird But True
By Alex Mitchell
Published Nov. 13, 2023, 5:13 p.m. ET
The mystery of a landmass that broke from modern-day western Australia and drifted to sea has been solved after 155 million years. Geologists from Utrecht University in the Netherlands have finally located the Down Under expanse — way down under the Earth’s surface.
The elusive, 3,106-mile stretch, now referred to as Argoland, was once part of the supercontinent Gondwana. It initially drifted northwest where several southeast Asian islands currently exist today, according to researchers. Despite the little remaining evidence of Argoland’s existence, the geologists’ detective work point beneath the jungles of Indonesia and Myanmar.
In their quest to learn more about Argoland, the researchers compared it to another prehistoric continent called Greater Adria, which was rediscovered in 2019. Adria also broke off into multiple fragments that were split amongst ocean basins before becoming a singular, tectonic plate. Centuries ago, it was integrated into Earth’s mantle, leaving only a top layer that formed mountains in southern Europe.
The search for Argoland in southeast Asia lent fewer clues as it did not leave traces within rock formations. It took researchers seven years to draw solid conclusions as they investigated the structure of several islands, including Sumatra, the Andaman Islands, Borneo, Sulawesi, and Timor.
University researcher Eldert Advokaat stated, “We were literally dealing with islands of information, which is why our research took so long. We spent seven years putting the puzzle together. The situation in Southeast Asia is very different from places like Africa and South America, where a continent broke neatly into two pieces. Argoland splintered into many different shards, which obstructed our view of the continent’s journey.”
Finally, Advokaat and his team learned that Argoland’s many fragments had reached their separate destinations all within the same time frame. They ultimately found that Argoland had shimmied between neighboring geological systems in both the Himalayas and the Philippines. This discovery was crucial in determining the greater yet hidden location of the continent — one made up of several fragments that became an archipelago separated by ocean basins rather than a single united landmass.
“The splintering of Argoland started around 300 million years ago. It was about 215 million years ago that an event caused the breakup to accelerate and shard into many, thin pieces,” explained Utrecht University geologist Douwe van Hinsbergen. Its uncovering is instrumental to Earth science. “Those reconstructions are vital for our understanding of processes like the evolution of biodiversity and climate, or for finding raw materials,” he said. “At a more fundamental level: for understanding how mountains are formed or for working out the driving forces behind plate tectonics; two phenomena that are closely related.”
