The Lost Continent of Zealandia

Zealandia is the geological continent that encompasses New Zealand and New Caledonia. It includes land that is mostly submerged, but during ice ages, was above sea level.

Zealandia is ​​5 million km² making it the eqivalent of two-thirds the size of its neighbour, Australia.It spans north to New Caledonia and further south than New Zealand's own sub-Antarctic islands. New Zealand comprises the largest part of Zealandia that is not submerged, followed by the main island (Grande-Terre) of New Caledonia. In geological history, these islands were the main mountain ranges of this continent when it was above sea level.

Zealandia Satellite Image Data

Zealandia as seen from satellite images.

According to scientists, Zealandia comes remarkably close to the Australia continent off the coast of Queensland, a mere 25km in fact. But what makes Zealandia a continent even though it is currently 93% covered by sea? First thing to consider is that much of the current continents such as Africa could be covered by sea in the distant future and that wouldn't affect their continent status. To be considered a continent rather than a micro-continent or fragment of another continent, certain criteria is required. The following is what distinguishes Zealandia as Earth's eighth continent.

• It sits above the surrounding sea floor with its own distinctive geology;
• It has a well-defined shape rather than a broken set of plateaus;
• The crust is thicker than the ocean floor around it;
• It also helps explain the movement of the other continents after Gondwana broke apart.

Zealandia on the Map

Approximate shape of Zealandia next to Australia.

The discovery of Zealandia was not sudden, but a slow realisation upon reflection of accumulated data. While there is no organisation responsible for defining continents like there is for planets, the aspiration for Zealandia to be recognized as a continent is not new. In fact, geophysicist Bruce Luyendyk coined the term 'Zealandia' back in 1995 and this is a fight that started two decades ago. So what has changed since then? The data now seems conclusive and the theories are approaching reality. Zealandia will likely be recognised as a gelological continent in time as further data is analysed and new material is written.

Geologist Nick Mortimer and lead author of the study published their findings in the Geological Society of America's Journal, GSA. He said the following to the media upon submission of their paper:

"the value of classifying Zealandia as a continent is much more than adding a new name to the list." "That a continent can be so submerged yet unfragmented" makes it useful for "exploring the cohesion and breakup of continental crust."

"If we could pull the plug on the oceans, it would be clear to everybody that we have mountain chains and a big, high-standing continent".

Zealandia, The Hidden Continent

The total land area of Zealandia above sea level (including lakes and rivers) is 286,655 km2 (110,678 sq mi). New Zealand comprises the vast majority at 267,988 km2 (103,471 sq mi or 93%). The realm of New Zealand today that is part of Zealandia includes the two main islands named North Island and South Island as well as many surrounding smaller islands such as Stewart Island. Outlying islands include: Antipodes Islands, Auckland Islands, Bounty Islands, Campbell Islands, and the Chatham Islands out east. However, the Kermadec Islands which belong to New Zealand today, are not part of Zealandia.

The islands that make up New Caledonia today sit in the northern portion of Zealandia. They comprise some 18,576 km2 (7,172 sq mi) or 7% of the area above sea level. The tiny remainder is made up of various outlying islands under Australian administration including the Lord Howe Island Group, Norfolk Island, as well as Elizabeth and Middleton reefs.

The Eighth Continent?

Read more: A new continent called Zealandia →