Australia is not only the smallest continent but also the largest island in the world. But the Lower Lands were not always so isolated; It was once part of a larger supercontinent. So when did Australia become its own continent?

Australia’s continental landmass is approximately 2,300 miles (3,700 km) from north to south and 2,485 miles (4,000 km) from east to west. Within an area of ​​2.97 million square miles (7.69 million square kilometers), Australia is home to the oldest known material of terrestrial origin on Earth: approximately 4.4 billion years old, from the Jack Hills region of Western Australia, according to a 2014 study. zircon crystals dating back to before. to work. In the journal Nature Geoscience.

The oldest parts of Australia are made up of three continent-sized pieces of rock known as cratons: the Northern, Southern and Western Australian cratons, geologist Alan Collins of the University of Adelaide in Australia told LiveScience. The younger eastern part of Australia consists of rocks formed at the edges of older parts of the continent over the last 500 million years.

Australia was once part of a much larger landmass known as Gondwana, which also included modern-day Africa, South America, Antarctica, India and Madagascar. Gondwana was once part of the supercontinent Pangea, from which it split about 200 million years ago, according to Monash University.

According to Collins, Gondwana began to break up about 180 million years ago. According to the Free University of Berlin, the eastern half, which includes Australia, Antarctica, India and Madagascar, is separated from the western half, which consists of Africa and South America.

Collins explained that Gondwana broke apart and plunged deeper into the Earth as its oceanic crust subducted, or slid, beneath the southern and eastern margins of Asia. The oceanic crust drags the rest of the tectonic plate with it, he said, and the northern edge of Gondwana is at the other end of that plate.

Eastern Gondwana lost more and more pieces over time. “Australia and Antarctica broke away from Gondwana as a single block about 135 million years ago,” geologist Patrice Ray of the University of Sydney told LiveScience.

This block broke away from Gondwana because the tectonic plate to the east of the block sank beneath the block. “This subduction zone explains the movement of the Australia-Antarctic Block eastward of Gondwana,” Ray said.

New Zealand was also once part of this breakaway bloc. However, about 100 million years ago, the landmass that now includes New Zealand (a largely submerged continent called Zealandia) broke away from present-day eastern Australia, partly due to intense volcanic activity.

According to Ray, Australia finally broke away from Antarctica and became its own continent when it moved northward from Antarctica about 35 million years ago. This event created the Southern Ocean that now surrounds Antarctica, Collins said.

Australia is still on the move. Australia is the fastest-moving tectonic plate on the planet, drifting at a rate of about 2.75 inches (7 centimeters) per year, Australian scientists Chris Rizos and Donald Grant wrote. 2017 articles on The Conversation.

“Australia is hurtling north as fast as your fingernails grow,” Collins said.

In about 20 to 30 million years, Australia “will probably replace East Asia,” Collins added. When Australia collide with Asia, its time as a continent in its own right will come to an end.