New Zealand sits atop a previously unknown continent - mostly submerged beneath the South Pacific - that should be recognised with the name Zealandia, scientists said on Friday.
Researchers said Zealandia was a distinct geological entity and met all the criteria applied to Earth's seven other continents including elevation above the surrounding area, distinctive geology, a well-defined area and a crust much thicker than that found on the ocean floor.
In a paper published in the Geological Society of America's Journal, GSA Today, they said Zealandia measured five million square kilometres and was 94 per cent underwater.
The paper's authors said it had only three major landmasses, New Zealand's North and South Islands to the south, and New Caledonia to the north.
The scientists, many from the official New Zealand research body GNS Science, as well as an Australian academic from the University of Sydney, said Zealandia was once part of the Gondwana super-continent but broke away about 100 million years ago.
"The scientific value of classifying Zealandia as a continent is much more than just an extra name on a list," they wrote.
"That a continent can be so submerged yet unfragmented makes it (useful)... in exploring the cohesion and breakup of continental crust."
Lead author Nick Mortimer said scientists have been gathering data to make the case for Zealandia for more than 20 years.
But their efforts had been frustrated because most of it was hidden beneath the waves.
"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," he told TVNZ.
The spatial limits of Zealandia. Source: GSA Today
Mortimer said he wanted Zealandia to become an accepted part of how the Earth is viewed.
"What we hope is that Zealandia will appear on world maps, in schools, everywhere," he said.
"I think the revelation of a new continent is pretty exciting."
The problem the scientists face in seeking recognition, however, is the nebulous definition of 'continent' where there is no scientific body that formally recognises and 'endorses' the land masses.
The study that appeared in GSA Today cited the 'Glossary of Geology', highlighting that "the last point - how a major piece of continental crust has to be called a continent - is almost never discussed".
"Perhaps this is because it is assumed that the names of the six geological continents ... suffice to describe all major regions of continental crust," the scientists said.
Brendan Murphy, a geologist at St. Francis Xavier University in Antigonish, agreed the article made clear an interesting grey area in the field.
“One of the main benefits of this article is that it draws attention to the arbitrary and inconsistent use of such a fundamental term as continent," he told journal Nature.
However support for recognition was not unanimous.
"So what?" Peter Cawood, a geologist at Monash University, said in response.
