Zealand has an area of about 5 million km2.
- author, Draft
- stock, BBC News World
Aristotle, Eratosthenes and, later, the cartographer Ptolemy called it Terra Australis Ignota.
In search of this imaginary continent, in classical Greece, believed to be on the other side of the world due to its geometric symmetry, Dutch explorer Abel Tasman discovered a new land in 1642, the islands we now know as New Zealand. . But what I was looking for seemed too small.
It took 375 years to confirm that the continent known as Cilandia actually existed, although it was largely invisible to the naked eye: It is 94% underwater.
Now, a new study has completed the definitive map of Zealandia, or as it is known in Maori, Te Riu-a-Māui.
In a study published in “Tectonics,” scientists at GNS Science in New Zealand have created a new detailed map of Zealandia’s borders, thanks to rock samples dug from the sea floor.
The continent stretches 5 million square kilometersAnd it is not until now that its complete surface has been established.
Its history is linked to the ancient southern supercontinent Gondwana, when it split hundreds of millions of years ago, forming the continents we know today and maybe six or seven depending on which country one studies.
Celandia separated about 80 million years ago, but unlike its neighboring continents, Antarctica or Oceania, Most of its parts were submerged.
Basalts, sandstones and pebbles
The islands of New Zealand, the French territory of New Caledonia, and the small Australian territories of Lord Howe Island and Paul’s Pyramid are the only remaining landmasses on the surface.
Being under the sea, Cilandia is small and poorly studied, creating controversy about its shape and limits. So far, only the southern part of the continent has been mapped.
With new research led by geologist Nick Mortimer, The missing two thirds are defined Existing maps have been refined, so “5 million km2 of land and sea reconnaissance geomapping of Zealand is now complete,” the study notes.
To do this, a team of geologists and seismologists examined samples of rocks and sediments collected on the sea floor, mostly from drilling, and samples that appeared on the shores of islands in the area.
They were analyzed and dated Basalt, sandstone and sandstone pebbles. The researchers found that these sandstones consist of Upper Cretaceous (about 95 million years old) and Lower Cretaceous (130 to 110 million years old) granite and volcanic pebbles. The basalts are of Eocene age (about 40 million years old).
These results, along with regional magnetic anomaly data and information from other surveys, helped scientists map the underwater geology of North Zealand.
After the first European sighting by Abel Tasman (who later named the island of Tasmania) in 1642, other explorers and scientists searched the waters of Zealand in search of the lost continent. without feeling them floating above him.
The first real clues to its existence were gathered by the Scottish naturalist James Hector, who in 1895 explored the islands off the south coast of New Zealand and concluded that the country was “the remnant of a mountain range that formed the crest of a great continent”. The area, which extended to the south and east, is now submerged.”
Then, in 1995, American geophysicist Bruce Luyendyk returned described the region as a continent and suggested calling it Zelandia.
image source, Ketty
Mount Cook is the tallest in New Zealand and the largest on the entire New Zealand continent.
Will it change?
Continental crust is typically about 40 km deep and significantly thicker than oceanic crust, which is typically only about 10 km.
Iceland has some 20 km deep Because its base expanded greatly when it separated from Gondwana. Being so thin, it eventually sank, though not to the extent of normal oceanic crust.
Scientists argue that, because of the height of its crust and the type of rocks that make it up, Zealandia is definitely a continent.
Apart from scientific curiosity, would it change anything if researchers defined Zeland as a new continent?
According to United Nations Convention on the Law of the SeaCountries can extend their legal boundaries beyond the exclusive economic zone 370 km from their coasts and claim their “extended continental shelf”, which includes all mineral and oil resources.
By proving that it is part of a larger continent, New Zealand could increase its land area sixfold.
This means that funding for ocean exploration has increased manifold in recent years.
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