Maps reveal what the 8th continent, Zealandia, looks like underwater

  • Scientists confirmed the existence of an eighth continent, called Zealandia, under New Zealand and the surrounding ocean in 2017.
  • Because 94% of Zealand’s 2 million square miles are underwater, mapping the continent is challenging.
  • The researchers have just released maps showing Zealandia in unprecedented detail, revealing its shape and how it formed millions of years ago.
  • Visit the Business Insider home page for more stories.

About 3,500 feet below the waves of the South Pacific lies a lost eighth continent.

Scientists confirmed that the submerged landmass, called Zealandia, was its own continent in 2017. But until now they had not been able to map its full extent.

On Monday, researchers at GNS Science in New Zealand announced that they had mapped the shape and size of the continent in unprecedented detail. They put their maps on an interactive website so that users could virtually explore the continent.

“We have made these maps to provide an accurate, complete and up-to-date image of the geology of the New Zealand and Southwest Pacific area, better than before,” said Nick Mortimer, who led the work. in a sentence.

Mortimer and his colleagues mapped the bathymetry surrounding Zealandia, the shape and depth of the ocean floor, as well as its tectonic profile, showing where Zealandia falls through the boundaries of the tectonic plate.

The maps reveal new information about how Zealandia formed before it submerged underwater millions of years ago.

An underwater continent nearly 2 million square miles in size

Zealandia’s area is nearly 2 million square miles (5 million square kilometers), about half the size of Australia.

But only 6% of the continent is above sea level. That part supports the northern and southern islands of New Zealand and the island of New Caledonia. The rest are underwater, making Zealandia difficult to study.

To better understand the submerged continent, Mortimer and his team mapped both Zealandia and the ocean floor around them. The bathymetric map they created (below) shows how high the mountains and the crest of the continent rise to the surface of the water.


A bathymetric map of Zealandia, showing the shape of the underwater continent.

GNS Science

It also represents the coasts, the territorial limits and the names of the main underwater features. The map is part of a global initiative to map the entire ocean floor of the planet by 2030.

The second map made by GNS scientists (below) reveals the types of crust that make up the underwater continent, the age of that crust, and major faults. The continental crust, the oldest and thickest type of earth crust that forms land masses, is shown in red, orange, yellow and brown. The oceanic crust, which is generally younger, is blue in color. The red triangles show where the volcanoes are.

New Zealand tectonic map

A tectonic map of Zealandia, showing the types and ages of the crust, major faults, and volcanoes that make up the continent.

GNS Science

This map also reveals where Zealandia is located through various tectonic plates, which of those plates are being pushed underneath each other in a process known as subduction, and how fast that movement is occurring.

Studying the tectonic machinations that underpin Zealandia today may reveal clues to how the continent formed in the first place.

Origins of Zealand’s 85 million years

Zealandia’s concept is 25 years old. Geophysicist Bruce Luyendyk coined the term in 1995.

Luyendyk previously told Business Insider that he never intended for the term to describe a new continent. Rather, the name originally referred to New Zealand and a collection of submerged pieces of bark that smashed the ancient Gondwana supercontinent about 85 million years ago.

“The reason I came up with this term is for convenience,” said Luyendyk. “They are pieces of the same thing when you look at Gondwana. So I thought, ‘Why do you keep naming this collection of pieces as different things?'”

Gondwana was formed when Earth’s ancient supercontinent, Pangea, split into two fragments. Laurasia in the north became Europe, Asia, and North America. Gondwana in the south dispersed to form modern Africa, Antarctica, South America, and Australia.

Pangea Map

A map of Pangea 200 million years ago, with blank tectonic plate boundaries.

Wikimedia Commons

Geological forces continued to reorganize these land masses, and Zealandia was forced under the waves 30 to 50 million years after Gondwana broke when the largest tectonic plate, the Pacific Plate, slowly subducted below it.

These maps show that Zealandia is a continent like the other 7

Until 2017, Zealandia was classified as a “microcontinent”, like the island of Madagascar. But according to Mortimer, Zealandia meets all the requirements for the state of the continent: it has clearly defined limits, occupies an area greater than 386,000 square miles (1 million square kilometers), rises above the surrounding oceanic crust, and has a continental crust thicker than That oceanic crust.

Therefore, these new maps offer more evidence that underwater land mass should be considered the eighth continent, Mortimer added.

“If we could disconnect the world’s oceans, it would be pretty clear that Zealandia stands out,” he told Science News in 2017, adding: “If it weren’t for ocean level, we would have long ago recognized Zealandia for what it was: a continent “.