An international group of geologists and seismologists examined rock samples from the bottom of the ocean to determine the boundaries of the hypothetical seventh continent (Zealandia). According to an elaborate estimate, the area of ​​the continent, including the submerged areas, is approximately 5 million km². This is about 1.5 times less than Australia.

About 83 million years ago, the Gondwana supercontinent was torn apart by geological forces, eventually forming the present-day continents. Researchers had previously shown that in addition to the six preserved continents (Eurasia, Africa, South America, North America, Australia and Antarctica), there was one more continent after the breakup, Zealandia, which was later submerged.

94% of Zealand’s territory is under water, with the remaining 6% comprising New Zealand and surrounding islands. Since Zeeland is under the ocean, it is as well studied as ordinary continents. Researchers developed the current maps of Zealandia based on an analysis of the origin of rocks and sediments lifted from the ocean floor.

By dating rocks and interpreting magnetic anomalies, geologists have mapped the major geological formations of North Zealand. The researchers found a mixture of sandstone from the Late Cretaceous period, approximately 95 million years old, and granite and volcanic pebbles, dating back to the Early Cretaceous period up to 130 million years ago. The basalts are newer; They are approximately 40 million years old and belong to the Eocene period.

The researchers also showed that internal deformation in both Zealand and West Antarctica indicates that stress caused the cracking of subduction plates that took in ocean water and formed the Tasman Sea.

After several million years, further separation of Antarctica continued to stretch the crust until it became thin enough to split and determine the fate of the largely submerged Zealandia. Source