Lost continent of Zealandia reveals its secrets after 375 years

Despite centuries of exploration, Earth continues to harbor secrets within its vast expanses. While geologists have mapped most of the planet's surface, significant discoveries still emerge. In 2017, geologists announced a remarkable finding in the Southern Hemisphere: an eighth continent. Named Zealandia, this landmass had been hiding in plain sight all along. The groundbreaking research was published in the journal Tectonics.

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The story of Zealandia's discovery spans nearly four centuries, beginning in 1642. Dutch captain Abel Tasman, under orders from the East India Company to explore the Southern Continent, set sail from Batavia on August 14, 1642. His journey took him westward to Mauritius in the Indian Ocean, as documented by Princeton University Library.

The return in Amsterdam of the second expedition to the East IndiesPainting by Hendrik Cornelisz Vroom via WikiCommons

During his expedition, Tasman's encounter with the local Māori people proved fateful. According to the BBC, tensions escalated when a group of Māori warriors attacked a small messenger boat traveling between the Dutch ships, resulting in four European deaths. The incident abruptly ended Tasman's mission.

Before departing, he named the site "Moordenaers (Murderers) Bay" and returned home, convinced he had found a vast new continent despite never returning to explore it further.

Nearly four centuries passed between Tasman's voyage and the continent's official discovery by geologists. The landmass was named "Zealandia" following a suggestion by American geophysicist Bruce Luyendyk, who first described the region in 1995. In the Māori language, Zealandia is known as "Te Riu-a-Māui."

A study published by GNS Science of New Zealand detailed how researchers collected rock samples by dredging from the Fairway Ridge to the Coral Sea. These samples were then geochemically analyzed to uncover the geological composition of Zealandia’s underwater region. Under the leadership of Nick Mortimer, the team examined the northern two-thirds of the submerged landmass, discovering a range of materials, including pebbly and cobbley sandstone, fine-grain sandstone, mudstone, bioclastic limestone, and basaltic lava. Radiocarbon dating indicated these rocks originated from various geological periods.

Dating back approximately 95 million years, the rocks and stones were traced to the Late Cretaceous period. Granite and volcanic pebbles discovered in the region were even older, estimated to be around 130 million years old, placing them in the Early Cretaceous period. In contrast, the basalts were relatively younger, likely formed about 40 million years ago during the Eocene period. “It is kind of cool,” Mortimer told the BBC. Andy Tulloch, a geologist at the New Zealand Crown Research Institute GNS Science and a member of the research team, noted, "This is an example of how something very obvious can take a while to uncover."

Spanning an impressive 4.9 million square kilometers, Zealandia is a massive continent roughly six times larger than Madagascar. However, the majority of its landmass lies hidden beneath the South Pacific Ocean. The only visible portion above sea level is found near Ball’s Pyramid on Lord Howe Island. Notably, Zealandia holds the distinction of being the smallest, thinnest, and youngest continent ever identified.

Typically, continental crust measures around 40 kilometers in depth, significantly thicker than oceanic crust, which averages about 10 kilometers. According to the researchers, Zealandia’s crust underwent extensive stretching, causing it to thin to approximately 20 kilometers before eventually sinking beneath the ocean. Today, with 95 percent of its landmass submerged, Zealandia remains a hidden realm on Earth, shrouded in enigmatic allure and rich with ancient geological tales.