March 10, 2017, 11:09 a.m.View more articles
For many years, people have been taught that the Earth has seven continents – but now a group of geologists is proposing that there is an eighth one, right underneath New Zealand. They’re calling it Zealandia!
The seven continents that most people are familiar with are North America, South America, Antarctica, Africa, Australia, Europe and Asia.
It’s quite difficult, however, to figure out exactly what a continent is, because people disagree on how you should classify one. Depending on where you live in the world, you might learn that there are seven, six or even five continents.
Generally speaking, a continent needs to follow four rules. First, it needs to be a huge piece of land with high mountains as well as areas that are close to the very bottom of the ocean. Second, a continent should have a distinctive range of rock types. Third, it should be clear to see where the continent’s edges are. And finally, it should be really, really big! So what’s the deal with this new continent? Geologists think that Zealandia broke off from the Australian continent about 60–85 million years ago. For a long time, scientists thought that this broken-off landmass just wasn’t big enough to be considered a continent – but after studying it in a lot more detail, they think it is big enough, and Zealandia should be named the eighth continent of the world!
So, what convinced them? Well, they looked at some maps of the seafloor around New Zealand. These maps revealed there was a large shallow area that stretched out for about 5 million km2 in all directions from the islands’ coast, before a sharp drop of about 2000 meters.
Ocean floors do change in depth, but not this abruptly in every direction. This made the scientists realize they weren’t looking at the seafloor, but instead at a huge mass of land, which had sunk about a kilometer below the water’s surface. This sunken landmass was huge – definitely big enough to be considered a continent. Only a tiny amount (6%!) of it is high enough to sit above sea level, forming New Zealand. Because so much of it is underwater, Zealandia is sometimes described as a “drowned continent”.
As there is no official list of continents, the group of scientists are trying hard to convince the world that they are right, and that Zealandia should be considered a continent. What do you think – have they convinced you?