Australia is not only the smallest continent, but also the largest island on Earth. But the land Down Under wasn’t always so isolated. It was once part of a larger supercontinent. So when did Australia become its own continent?
Australia’s continental land measures Approximately 2,300 miles (3,700 km) from north to south and 2,485 miles (4,000 km) from east to west. Within his 2.97 million square miles (7.69 million square kilometers) of Australia lies the oldest known material of terrestrial origin on Earth. It is a zircon crystal from the Jack Hills region of Western Australia that dates back approximately 4.4 billion years. According to a 2014 study published in the journal Nature Geoscience..
Australia’s oldest regions are three continent-sized blocks of rock known as cratons. The cratons of Northern Australia, South Australia, and Western Australia. alan collinsgeologists from the University of Adelaide in Australia told Live Science. The young eastern part of Australia is made up of rocks that formed at the edge of older regions of the continent over the past 500 million years.
Australia was once part of a much larger continent known as Gondwana, which also included modern-day Africa, South America, Antarctica, India, and Madagascar.Gondwana itself was once part of a supercontinent pangeaIt separated from there about 200 million years ago, According to Monash University.
Gondwana began to break up about 180 million years ago, Collins said. The eastern half, which includes Australia, Antarctica, India, and Madagascar, is separated from the western half, which consists of Africa and South America. According to the Free University of Berlin.
Related: Will Africa split into two continents?
Gondwana broke up as oceanic crust subducted, or slid, beneath the southern and eastern margins of Asia and fell into the deep ocean. earthexplained Collins.This oceanic crust dragged in the rest structural plate And the northern edge of Gondwana is on the other side of this plate, he said.
East Gondwana lost more parts over time. “Australia and Antarctica separated as one block from Gondwana about 135 million years ago.” Patrice Raya geologist at the University of Sydney told Live Science.
The block separated from Gondwana because a tectonic plate to the east of the block subducted beneath the block. “this subduction zone “It corresponded to the eastward movement of the Australian and Antarctic blocks away from Gondwana,” Ray said.
New Zealand was also once part of this breakaway bloc. But about 100 million years ago, a largely submerged continent called Zealandia, the landmass that now includes New Zealand, arose. Separated from present-day eastern Australia Partly due to massive volcanic activity.
Australia eventually separated from Antarctica and became its own continent about 35 million years ago, when the former drifted north from the latter, Ray said. This event created the Southern Ocean, which now surrounds Antarctica, Collins said.
Australia is still moving. Australian scientists Chris Rizos and Donald Grant write that Australia is drifting at a rate of about 2.75 inches (7 centimeters) per year, making it the fastest-moving tectonic plate on Earth. . 2017 article from The Conversation.
“Australia is moving north quite fast, as fast as a fingernail grows,” Mr Collins said.
In about 20 to 30 million years, Australia “will likely skid across East Asia,” Collins added. Once Australia collides with Asia, the days of Australia as its own continent will come to an end.