The New Zealand continent

Te Ika-a-Māui and Te Waipounamu - New Zealand’s main islands – have long been recognised for their distinctive forms. Polynesian oral histories describe a powerful demi-god catching a great fish (the North Island) from his canoe (the South Island). Captain James Cook mapped the islands of Aotearoa on his first visit in 1769-70. Unknown to many, much of New Zealand’s landmass lies hidden offshore. The geology team at GNS Science tells us more.

First of all, what is the definition of a continent?

The standard dictionary definition of a content is ‘one of Earth’s large continuous landmasses’. But, from a geological point of view this is a narrow and incomplete way to look at continents. All of Earth’s major landmasses are surrounded by submarine continental shelves. To geologists these shelves are also parts of continents. They have the same kinds of rock and when sea levels are low during ice ages, the shelves become land.

Tell us about the discovery of the New Zealand continent.

Te Riu-a-Māui/Zealandia was discovered progressively in more than a century of research and marine expeditions. The wide continental shelves around New Zealand and New Caledonia were shown on maps in the early 1900s. Since the 1990s, more and more continental rocks such as granite and greywacke have been sampled from submarine Te Riu-a-Māui/ Zealandia. In the past decade we have finally gathered enough evidence and confidence to draw sharp lines around Te Riu-a-Māui/Zealandia’s limits and put it on the map.

Te Riu-a-Māui - Zealandia was a sold-out set of two 1oz silver proof coins issued in February 2020. It has a maximum worldwide mintage of 400 sets. What is the meaning of the name Te Riu-a-Māui?

Riu conveys a picture of a basin or hull (e.g. of a canoe) that encloses many things and holds them together. Te Riu-a-Māui literally means the entire hills, valleys and plains of Māui - the great Polynesian ancestor and explorer of the Pacific Ocean. The name was recommended by Associate Professor Mānuka Hēnare of the University of Auckland. It’s a very appropriate name for the Pacific’s continent.

Why is it important to GNS Science that Te Riu-a-Māui/

Zealandia gains global recognition?

Te Riu-a-Māui/Zealandia is five million square kilometres in area. That’s two thirds the area of Australia. Putting

Earth’s eighth continent on a world map simply conveys a more accurate picture of what’s here in our corner of the planet. In terms of submarine geology, knowing there’s a continent out there is important background information for natural resources and natural hazards.

A knowledge of the changing latitude, climate and land area of Te Riu-a-Māui/Zealandia provides a useful backdrop for biologists to study the origins of our native flora and fauna. It is also important for all New Zealanders to understand that they live on a continent and that the country does not end at the beach. If we want to manage our environment, at a minimum we need to understand its extent and shape. Where can people learn more about New Zealand’s geology? There are lots of books and online resources. For a start, try www.gns.cri.nz/Home/Learning and gsnz.org.nz.