Science Saturday

The Lost Continent Beneath The Pacific Ocean

If there's one thing that excites us more than the idea of alien planets, it's the thought of what might be waiting beneath the surface of the ocean. Cthulu? Snorks? The lost continent of Atlantis? Unfortunately, science is a big party-pooper that says that probably none of those are actually real. Except...there really is a lost continent in the Pacific Ocean, and its highest point is the only part that's breached the surface. You know it as New Zealand, but there's a whole lot more Zealand where that came from.

Looking For Atlantis

Sail west from Sydney and you'll find Zealandia. Sort of. You won't be able to see it (not most of it, anyway), but deep beneath the ocean is a chunk of land spread out over 4.9 million square kilometers (about 3 million square miles) that broke off from Australia about 75 million years ago. Generally, we don't think of land masses as being continents if they're underwater — actually, we often don't even consider them to be land masses. But Zealandia meets pretty much all of the criteria: elevation above the surrounding area, a distinctive geology, a well-defined area, and a crust much thicker than that found on the ocean floor.

In one of the most intensive explorations of a "lost continent" ever, the Australian National University has launched a drill ship to explore Zealandia. The mission of the JOIDES Resolution is to collect sediment from the continental crust beneath the ocean, and test our theories about how and when Zealandia formed. Scientists currently believe that it was once a part of Gondwana, the supercontinent that also included Australia, Antarctica, Africa, and South America. But it probably broke off about 75 million years ago, and over the course of about 20 million years gradually spread itself so thin that it sank like an Oreo in milk. With core samples and mineral deposits, scientists will be able to strengthen these theories — or throw them out entirely.

An Army Of Atlantises

We've actually had an idea of Zealandia's existence since about 1919 (when it was known as Tasmantis), but it's not the only sunken continent on the planet. Another, much smaller, leftover of the great Gondwana break-up was discovered in 2017 and named "Mauritia" after Mauritia, one of its only parts to actually break the surface.

There are quite a few more of these continental crumbs, in fact, but only Zealandia has been deemed big enough to actually be described as a continent. The others, including Mauritia, Madagascar, and a bunch of tiny underwater islands you've probably never heard of, have all been deemed "microcontinents" or "continental fragments." But we prefer to think of them all as Snork sanctuaries.

Zealandia: The Ancient Continent Of New Zealand

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Key Facts In This Video

  1. About 26 million years ago, Zealandia (the ancient continent of New Zealand) almost disappeared beneath the ocean. 00:01

  2. What saved New Zealand from becoming completely submerged with the rest of Zealandia was the collision between the Australian and Pacific plates. 00:11

  3. A series of underwater blasts over 4 million years is what brought the Chatham Islands above sea level. 01:34

Written by Reuben Westmaas August 14, 2017