Geologists confirmed the existence of a hidden continent named Zealandia beneath the South Pacific Ocean. Covering approximately five million square kilometers—about the size of India—the submerged landmass has remained largely hidden, with ninety-five percent of its surface submerged beneath the waves.
A 2023 study titled Reconnaissance Basement Geology and Tectonics of North Zealandia, published in the journal Tectonics by the American Geophysical Union, provided details about the geology of Zealandia. Researchers at GNS Science in New Zealand, including Dr. Nick Mortimer, undertook research to map and understand the vast continental area.
"For decades, many geologists assumed that Zealandia is of continental nature, but its classification as a separate continent was not widely accepted, New studies supported by advanced techniques, such as geochronology, have provided strong evidence to classify Zealandia as a continent.
Zealandia's formation is linked to the ancient supercontinent Gondwana, which more than 100 million years ago included present-day territories of South America, Africa, Antarctica, Australia, and parts of Asia. About 85 million years ago, Zealandia began to separate from Gondwana and initially remained above sea level. Over millions of years, tectonic forces thinned the crust of Zealandia, ultimately pulling most of the continent beneath the ocean's surface.
Using geochronology methods—which determine the age of rocks based on measuring radioactive decay—researchers mapped the main geological units of northern Zealandia. By collecting rock samples, including basaltic lavas, sandstone pebbles, cobbles, mudstones, and bioclastic limestones, they traced a timeline of the geological formation of the Zealandia region.
"By dating these rocks and studying the magnetic anomalies they presented, we were able to map the major geological units across North Zealandia," the researchers explained. Magnetic data played a role in confirming the hidden shape of Zealandia, as the analysis of changes in the Earth's magnetic field recorded in Zealandia's crust helped mark the continent's boundaries.
The combination of magnetic anomalies and rock ages revealed geological patterns that reflect those observed in known continents. The structural coherence across the northern half of Zealandia provided strong evidence of its continental nature. The consistent signals supported the idea that Zealandia was not merely random oceanic crust—it was structured like a real continent and shelters characteristic geological units of continental crust, not just fragments of oceanic crust.
"Zealandia's submerged status in no way diminishes its geological significance," said Dr. Nick Mortimer. He added, "Today, although it is mostly submerged, Zealandia retains enormous scientific value."
Researchers identified remnants of sandstone, volcanic gravel, and basaltic lava in Zealandia, which are typical of continental environments and provide a record of its geological past. These rock samples date from the Early Cretaceous (100 to 146 million years ago) to the Eocene (34 to 56 million years ago), suggesting that parts of the continent remained above water for a long time before submerging completely.
Despite the progress made, large portions of Zealandia remain unexplored, making its existence important for scientific research. Scientists hope to find additional clues to outline the structure and past of Zealandia. Technologies such as seismic imaging and deep-water drilling could reveal more details about Zealandia's internal configuration.
Written with the help of a news-analysis system.