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 Zealandia’s 2 million square miles are underwater, mapping the continent is a challenge.
  • Researchers have just released maps that show Zealandia in unprecedented detail, revealing its shape and how it formed millions of years ago.
  • Visit the Business Insider homepage for more stories.

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

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

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 can virtually explore the continent.

“We created these maps to provide an accurate, complete and up-to-date picture of the geology of New Zealand and the South West Pacific region – better than before,” said Nick Mortimer, who led the works. in a report.

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 across the tectonic plate boundaries.

The maps reveal new information about the formation of Zealandia before it was submerged millions of years ago.

An undersea continent of nearly 2 million square miles

Zealandia has an area of ​​almost 2 million square miles (5 million square kilometers), about half the size of Australia.

But only 6% of the continent is above sea level. This part underlies the northern and southern islands of New Zealand and the island of New Caledonia. The rest is underwater, making Zealandia difficult to keep an eye on.

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

Bathymetric

A bathymetric map of Zealandia, which shows the shape of the continent underwater.

GNS Sciences


It also depicts the coasts, territorial boundaries, and the names of major 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 undersea continent, the age of this crust, and the main faults. The continental crust – the oldest and thickest type of earth’s crust that forms landmasses – is shown in red, orange, yellow, and brown. The oceanic crust, usually younger, is blue. The red triangles indicate where the volcanoes are located.

New Zealand tectonic map

A tectonic map of Zealandia, which shows the types and age of the crust, major faults and volcanoes that make up the continent.

GNS Sciences


This map also reveals where Zealandia is on various tectonic plates, which of these plates are pushed under each other in a process known as subduction, and how fast that movement is occurring.

Studying the tectonic machinations that underlie Zealandia today may reveal clues to the continent’s initial formation.

Zealandia’s 85 million year old origins

The concept of Zealandia is 25 years old. Geophysicist Bruce Luyendyk coined the term in 1995.

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

“The reason I came up with this term is for convenience,” Luyendyk said. “It’s bits of the same when you look at Gondwana. So I was like, “Why do you keep naming this collection of coins as different things?” “”

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

Map of Pangea

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

Wikimedia Commons


Geological forces continued to reorganize these land masses, and Zealandia was forced under the waves some 30 to 50 million years after the Gondwana rupture as the largest tectonic plate – the Pacific plate – slowly subducted. below.

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 ticks all the boxes for continent status: it has clearly defined boundaries, occupies an area greater than 386,000 square miles (1 million square kilometers), is elevated above the surrounding oceanic crust, and has a continental crust thicker than this oceanic crust.

These new maps therefore offer further evidence that the submarine land mass should be considered the eighth continent, Mortimer added.

“If we could unplug the world’s oceans, it would be quite clear that Zealandia is standing out,” he told Science News in 2017, adding, “If it hadn’t been for the sea level , we would have long ago recognized Zealandia for what it was: a continent. “


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