Under the waves of Pacific Ocean lies a giant land that once was called a continent: Zealandia, geologists say.
Zealandia is 5 million square kilometers big, including New Zealand and New Caledonia. A team of scientists from New Zealand, Australia, and New Caledonia argue in the March/April issue of GSA Today that this single crust is significantly separated from Australia.
“If you could pull the plug on the world’s oceans, then Zealandia would probably long ago have been recognized as a continent,” says team leader Nick Mortimer, a geologist at GNS Science in Dunedin, New Zealand.
“The results are pushing us to rethink how broadly we can or should apply the established definition of geological continental landmasses,” says Patricia Durance, a mineral geologist at the GNS Science office in Lower Hutt, New Zealand.
The researchers concluded Zealandia ought to be one of the continents. Zealandia didn’t break away from another continent, as it was thought to be in the past. The India-sized continent should be treated as the seventh continent of the world.
“If the elevation of Earth’s solid surface had first been mapped in the same way as those of Mars and Venus – which lack the arbitrary datum of opaque liquid oceans – we contend that Zealandia would, much earlier, have been investigated and identified as one of Earth’s continents,” the researchers noted.
“This is not a sudden discovery but a gradual realization; as recently as 10 years ago we would not have had the accumulated data or confidence in interpretation to write this paper.”
The scientists said classifying the area as one continent wasn’t just a matter of putting “an extra name on a list”.
“That continent can be so submerged yet unfragmented makes it a useful and thought-provoking geodynamic end member in exploring the cohesion and break-up of continental crust.”