Geologists matching rocks from opposite sides of the globe have found that part of Australia was once attached to North America 1.7 billion years ago.
Researchers from Curtin University in Australia examinedrocks from the Georgetown region of northern Queensland.
The rocks — sandstone sedimentary rocks that formed in a shallow sea — had signatures that were unknownin Australia but strongly resembled rocks that can be seen in present-day Canada.
The researchers, who described their findings online Jan. 17 in the journal Geology, concluded that the Georgetown area broke away from North America 1.7 billion years ago.
Then, 100 million years later, this landmass collided with what is now northern Australia, at the Mount Isa region.
[Photo Timeline: How the Earth Formed]