Zealandia, also known as Te Riu-a-Māui or Tasmantis, is Earth's eighth continent. It is mostly submerged about 3,500 feet under the South Pacific. In 2023, geologists concluded the meticulous mapping of its entire 2 million square miles using data from ocean-floor rock samples. This refined map sheds light on Zealandia's unique geological history.
The continent is now 94% submerged, with only 6% forming New Zealand and its neighbouring islands. The map shows that Zealandia was once a much larger continent, with a landmass that was comparable to Australia. However, over time, Zealandia was gradually submerged by the ocean.
History of Zealandia
Earlier, geologists deemed that Zealandia was formed over 550 million years ago when Gondwana, a supercontinent that included Africa, South America, Australia, Antarctica, and India, began to break apart. Around 83 million years ago, Zealandia separated from Australia and Antarctica and began to submerge beneath the ocean.
Approximately 23 million years ago, the landmass may have been completely submerged. Today, most of the landmass (94%) remains submerged beneath the Pacific Ocean. New Zealand is the largest part of Zealandia that is above sea level, followed by New Caledonia.
However, a 2021 study suggests that Zealandia is 1 billion years old, about twice as old as geologists previously thought. This would make Zealandia the oldest continent on Earth. The study found that the oldest rocks on Zealandia are around 1 billion years old.
Zealandia is a submerged continent with a total area of approximately 4,900,000 square kilometer's (1,900,000 square miles). This makes it substantially larger than any other microcontinent or continental fragment. If it were classified as a microcontinent, Zealandia would be the largest in the world, with an area six times greater than Madagascar, the next-largest microcontinent. It is also more than half the size of Australia.