Context

New Zealand recently published two new maps which cover the shape of the ocean floor and Zealandia’s tectonic profile, which collectively help tell the story of the continent’s origins.

About

Considered to be a lost ‘eighth continent’ that got submerged underwater millions of years ago, the land mass is called Zealandia. 

• Researchers from GNS Science in New Zealand have now mapped the shape and size of the continent with utmost detail.
• For the mapping, the researchers analysed the bathymetry — the shape and depth of the ocean floor — around Zealandia.
• In addition, they studied its tectonic profile to accurately locate Zealandia across tectonic-plate boundaries.
• The newly created maps bring to light previously unknown information about the formation of Zealandia.
  
  
  

Lost eighth continent of earth

• Till 2017, Zealandia was classified as a “microcontinent,” much like the island of Madagascar.
• The landmass has “clearly defined boundaries, occupies an area greater than 386,000 square miles (1 million square kilometers), is elevated above the surrounding ocean crust, and has a continental crust thicker than that oceanic crust
• Zealandia’s total area has been mapped to be nearly 2 million square miles (5 million square kilometers).
• At this measure, Zealandia is about half the size of Australia, however, only 6% of the continent is above sea level.

How did the continent sink?

• The idea of a potential continent in this area has been around for some time, and the name “Zealandia” was first coined by geophysicist Bruce Luyendyk in 1995.
• The dedicated study of this area, stretching about 5 million square kilometers (about 1.93 million square miles), has since determined it is not just a group of continental islands and fragments, but a continental crust large and separate enough to be officially declared a separate continent.
• Zealandia used to be part of Gondwana, the supercontinent that once held many of the continents such as Africa and South America.
• About 85 million years ago, Zealandia split off from Gondwana. The drifting, shifting land mass, about half the size of Australia, was home to dinosaurs and lush rainforest.
• Then, millions of years later, the world’s tectonic plates pieces of the Earth’s crust began reorganizing themselves, in a period of dramatic geological change that also created the Pacific “Ring of Fire,” a belt in the Pacific where the world’s most active volcanoes are located.
• During this time, the Pacific Plate the world’s largest tectonic plate is believed to have sank below the continental crust of Zealandia.
• This process, called subduction, caused the root of the continent to break off and sink as well

The present scenario

• About 94% of Zealandia is now submerged underwater -- but some parts of the continent are still above land, making up New Zealand and other small islands.
• The highest point of Zealandia is Aoraki--Mount Cook at 3,724 meters (12,218 feet).
• There is still much unknown about the continent and whether the discovery of Zealandia could change historical climate models.
• As more research emerges, the interactive website and maps will be updated to reflect what we know.