In the past, it was believed that Zealandia was no more than 500 million years old. New research, however, found that these estimates were incorrect.
As early as 2017, eleven geologists from New Zealand said they had discovered a sunken continent – Zealandia. People have been theorizing about the existence of Zealandia for more than a hundred years, but scientists have received new confirmations of their hypothesis that it exists only recently.
Sunken Continent Zealandia Twice As Old as Initially Thought
Should Zealandia be called a continent?
Initially, researchers debated whether the submerged land could be called a continent. It meets many criteria for such objects. One of the key characteristics is the existence of well-defined boundaries. Although the smallest continent is much larger, any new potential landmass should cover an area of more than one million square kilometers in order to be considered a continent. Moreover, it should be above the oceanic crust and have a thicker continental crust.
However, Zealandia does not meet one criterion – age. The oldest samples of it are estimated at the age of 500 million years. All other known continents are at least twice as old.
A new study, the results of which were published recently, found that these estimates were incorrect. Part of the sunken continent, whose origins are shrouded in mystery, turned out to be twice as old as geologists had previously predicted. As a New Zealand researcher notes, he no longer has any doubt that he lives on a separate continent.
But what is the exact history of the “new continent”? In modern days, 94% of the hypothetical continent is underwater. Once, it was part of the supercontinent Gondwana, but it broke off around 85 million years ago. Fast-forward another 30-50 million years, and Zealandia was almost entirely submerged under the waves.
Previous research suggested that the continent is about 500 million years old. The results of new studies, performed on 169 chunks of granite from Zealandia showed that it was once part of a much older supercontinent called Rodinia.
Much older than anticipated
Scientists consider that its formation began between 1.3 billion and 900 million years ago, which means that it is much older than previous estimates.
Earliest clues of Zealandia’s existence
While most of what we know about Zealandia was found in recent years, the first clues were suggested by James Hector, a Scottish naturalist, after his voyage in the area of New Zealand in 1895. He suggested that the country was once part of a large mountain chain that is now submerged.
Definition of a continent
We already mentioned the criteria needed for Zealandia to be considered a continent. But it is these same requirements that made it impossible for scientists to find the 8th continent earlier. Geologists only agreed to the current definition of a continent in the 1960s.
The name Zealandia was suggested in 1995 when scientific attention once again fell on the hypothetical continent and has been used since then.
Earth’s 8th continent?
With this information, should it be considered as the new 8th continent? With the help of the global initiative to map the entire ocean floor, scientists were able to map the size and coastlines of the hypothetical continent in incredible detail. If we didn’t mention it already, Zealandia is about half the size of Australia, making it the smallest continent on Earth, if ever confirmed.
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• BBC Future. (n.d.). The missing continent it took 375 years to find.
• Witze, A. (2017, February 16). Geologists spy an EIGHTH continent: Zealandia. Nature News.
• Woodward, A. (2021, August 14). A fragment of a mysterious 8TH continent is hiding under New Zealand – and it’s twice as old as scientists thought. Business Insider.
• Woodward, A. (n.d.). A chunk from the sunken continent of zealandia is twice as old as we thought. ScienceAlert.