New Zealand Is Not Just A Small Bunch Of Islands – It’s The Lost Continent Of Zealandia

A group of geologists is making a new push to add an eighth continent to the accepted list, known as Zealandia. The scientists have been working for two decades gathering data to support their claim that New Zealand is just the tip of a huge submerged landmass that deserves to be called a continent.

“Being more than 1 million square kilometers in area, and bounded by well-defined geologic and geographic limits, Zealandia is, by our definition, large enough to be termed a continent,” said lead author Dr Nick Mortimer in a press release.

Mortimer heads a team of eight geologists at GNS Science, which is a New Zealand Crown Research institute focused on geology, geophysics and nuclear science. The rest of the paper’s contributors hail from Victoria University, the Geological Survey of New Caledonia and the University of Sydney.

According to their paper, published in the journal of the Geological Society of America GSA Today, the New Zealand islands are the tips of mountains belonging to a fairly large continent that is 94% hidden under the sea.

This is a claim the team has made before, but Mortimer insists this paper is significant as it is the culmination of more than 20 years of their research.

“Based on various lines of geological and geophysical evidence, particularly those accumulated in the last two decades, we argue that Zealandia is not a collection of partly submerged continental fragments but is a coherent 4.9 square million kilometer continent,” he said.

The research shows that Zealandia is a young, thin continent with crust thickness of between 10km and 30km, increasing to 40km under parts of the South Island. The submerged continent is around the same area as greater India, making it the seventh largest geological continent.

Scientists don’t just want the continent accepted for the prestige of New Zealand, but because of the opportunity it presents to investigate the geological processes of continents at an earlier stage.

“The importance of Zealandia is not so much that there is now a case for a formerly little-known continent, but that, by virtue of its being thinned and submerged, but not shredded into microcontinents, it is a new and useful continental end member,” the paper says.

“Zealandia started to separate from [ancient supercontinent] Gondwana in the Late Cretaceous as an ~4000-km-long ribbon continent, but has since undergone substantial intra­continental deformation, to end up in its present shape and position.

“To date, Zealandia is little-mentioned and/or entirely overlooked in comparative studies of continental rifting and of continent-ocean boundaries. By including Zealandia in investigations, we can discover more about the rheology, cohesion, and extensional deformation of continental crust and lithosphere,” it adds.

There is no official body that can define Zealandia as a continent. However, the team argues that it meets the generally agreed principles of a continent:

(1) high elevation relative to regions floored by oceanic crust;

(2) a broad range of siliceous igneous, metamorphic, and sedimentary rocks;

(3) thicker crust and lower seismic velocity structure than oceanic crustal regions;

(4) well-defined limits around a large enough area to be considered a continent rather than a microcontinent or continental fragment

“Currently used conventions and definitions of continental crust, continents, and microcontinents require no modification to accommodate Zealandia,” the paper says.

“The scientific value of classifying Zealandia as a continent is much more than just an extra name on a list. That a continent can be so submerged yet unfragmented makes it a useful and thought-provoking geodynamic end member.”

Forbes 

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