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Australia is not only the smallest continent but also Earth ’s magnanimous island . But the land Down Under was n’t always so marooned ; it was once part of a expectant supercontinent . So when did Australia become its own continent ?
Australia ’s continental landmass measuresabout 2,300 miles ( 3,700 kilometers ) from north to south and 2,485 miles ( 4,000 km ) from east to west . Within its 2.97 million square mi ( 7.69 million straight km ) , Australia is plate to the oldest know material of terrestrial origin on Earth : zircon crystals from the Jack Hills area of western Australia date to about 4.4 billion long time ago , concord to a 2014 survey in the daybook Nature Geoscience .
When did Australia — which is both the world’s smallest continent and Earth’s largest island — become a loner?
The oldest parts of Australia are three continent - size chunk of rock acknowledge as cratons : the North , South and West Australian cratons , Alan Collins , a geologist at the University of Adelaide in Australia , evidence Live Science . The younger , eastern part of Australia is made up of John Rock that formed on the border of the continent ’s older regions over the past 500 million years .
Australia was once part of a much larger landmass known as Gondwana , which also included what are now Africa , South America , Antarctica , India and Madagascar . Gondwana was itself once part of the supercontinentPangaea , from which it break off about 200 million years ago , agree to Monash University .
Gondwana begin splintering about 180 million years ago , Collins said . Its eastern half — which included Australia , Antarctica , India and Madagascar — separate from its western one-half , made up of Africa and South America , according to the Free University of Berlin .
When did Australia — which is both the world’s smallest continent and Earth’s largest island — become a loner?
Related : Is Africa splitting into two continents ?
Gondwana crack up because pelagic impertinence subducted , or slid , under the southerly and easterly tolerance of Asia , fall into the deepEarth , Collins explained . This pelagic crust dragged the residuum of itstectonic platewith it , and the northern margin of Gondwana was on the other ending of this plate , he said .
East Gondwana , in bit , lost more and more parts over time . " Together as a undivided block , Australia and Antarctica separated from Gondwana about 135 million ago,“Patrice Rey , a geologist at the University of Sydney , told Live Science .
This block separated from Gondwana because a architectonic plate east of this block subducted under the block . " Thissubduction zoneaccommodated the eastward move of the Australia - Antarctica block away from Gondwana , " Rey aver .
New Zealand was once part of this breakaway block , too . However , about 100 million year ago , the land mass that now includes New Zealand — the largely submerged continent dubbed Zealandia — split from what is now eastern Australiain part due to major volcanic bodily process .
— When did Antarctica become a continent ?
— How many tectonic plates does Earth have ?
— Do the Pacific Ocean and the Atlantic Ocean mixture ?
Australia ultimately separated from Antarctica to become its own continent about 35 million year ago , when the former blow northward aside from the latter , Rey said . This event create the Southern Ocean that presently surrounds Antarctica , Collins said .
Australia is still on the move . Drifting at about 2.75 in ( 7 centimeters ) per year , Australia is the planet ’s quickest - be active tectonic plate , Australian scientists Chris Rizos and Donald Grant wrote ina 2017 piece in The Conversation .
" Australia is moving quite fast north — as fast as your fingernail grow , " Collins enunciate .
In about 20 million to 30 million years , Australia " is likely to sideswipe East Asia , " Collins added . Once Australia collides with Asia , its sentence as its own continent will amount to an end .
