Scientists confirm the location of Earth’s missing eighth continent

In the waters of the South Pacific, geologists have identified a massive land area that has stayed mostly hidden below the surface. Many scientists now consider it a separate continent spanning nearly two million square miles (5 million square kilometers).

Experts call this sunken stretch of terrain Zealandia, and only about five percent of it breaks the ocean’s surface in places like New Zealand.

Researchers suggest that it split from larger landmasses many millions of years ago, making it the planet’s newest candidate for a fully fledged continent.

Ancient beginnings of Zealandia

Nick Mortimer from GNS Science has been at the forefront of examining how Zealandia formed. He and his colleagues looked back over 100 million years to when Gondwana was a huge supercontinent consisting of South America, Africa, Antarctica, Australia, and parts of Asia.

Pieces of Gondwana started drifting apart over time, with one section eventually evolving into Zealandia. The land that once stood high above sea level began to slip below the ocean’s surface because of changes in tectonic forces.

As movement within Earth’s outer layers continued, Zealandia gradually edged away from West Antarctica about 85 million years ago. Later, it drifted apart from Australia and became an isolated mass.

The crust in this isolated region lost thickness and cooled, which led to the land’s final dip below sea level. Today, it remains mostly out of sight, but its presence has significant scientific value.

Geological findings across Zealandia

While plenty of geologists guessed for decades that this submerged area was continental in nature, the label of a separate continent was not widely accepted. Many believed these underwater ridges and plateaus were just fragments.

Fresh data has now changed that perspective. Researchers used geochronology, a method that determines rock ages through radioactive decay, to establish a timeline for the region’s formation.

“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 said.

Evidence showed that this underwater land shares key traits with other recognized continents.

The scientists collected rock samples in the northern sections of Zealandia using advanced dredging tools. Their results mapped out sandstone, volcanic pebbles, and basaltic lavas with ages ranging from the Early Cretaceous to the Eocene epoch.

Confirmed by magnetic clues

Magnetic data played a key role in confirming Zealandia’s hidden shape. Using measurements of magnetic anomalies, researchers spotted clear patterns tied to ancient volcanic activity that helped mark the continent’s boundaries.

These anomalies aligned with rock ages from dredged samples, revealing stretches of intraplate basalts which were formed during the Cretaceous and Eocene periods.

The consistent signals supported the idea that Zealandia wasn’t just random ocean crust – it was structured like a true continent.

Tectonic plates explained

Much of Zealandia’s descent can be traced back to movements of tectonic plates, which are massive slabs of Earth’s surface that shift over time. In some regions, plates converge, causing one plate to sink beneath the other in a process called subduction.

Zealandia’s thinning crust was shaped by such shifts. Plate stretching allowed deep ocean waters to flood over much of the land, leaving only a few islands sticking out above sea level.

Why does any of this matter?

Scientists find Zealandia valuable for learning how continents evolve under changing plate conditions. This sunken landmass preserves clues about Earth’s past that might not be visible on continents above the surface.

“Zealandia’s underwater status in no way diminishes its geological significance,” stated a GNS Science researcher. That perspective encourages a closer look at how plate dynamics affect continental shapes and positions over geologic time.

Many sedimentary rocks within Zealandia date to the Late Cretaceous period, indicating that parts of it remained above water long after it separated from other continents. Basalt samples reveal younger volcanic pulses that arose when new plate boundaries formed.

The combination of rock dating methods, magnetic signatures, and tectonic mapping helped define where Zealandia’s boundaries lie. Researchers now have a clearer view of this submerged landscape and its distinct geological zones.

Ongoing exploration of Zealandia

Large portions of Zealandia remain unexplored. Technologies like seismic imaging and deep-sea drilling will likely uncover more details of its structure and past.

Some investigators hope to find further clues about how drifting continents influence sea level, climate patterns, and the distribution of plants and animals. Each discovery could refine our understanding of how Earth’s surface rearranges itself.

Several areas on the planet exist as microcontinents or submerged fragments, but Zealandia stands out for its size and completeness. It is not only a trove of history but also a reminder that Earth still holds secrets.

Future fieldwork and collaborative international studies may refine ideas about how Zealandia contributes to global tectonic activity.

This hidden expanse highlights the complexities of continental classification and sparks discussion about what qualifies as a continent.

The study is published in the journal Tectonics.

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