Zealandia

Zealandia is a massive, nearly submerged landmass located in Oceania.

While we usually think of continents as large land areas, most of Zealandia is hidden. Scientists describe it as a piece of continental crust. Some geologists call it a microcontinent or a continental fragment. However, many experts argue it should be classified as a full continent. This argument is based on its unique crustal thickness and density.

The history of Zealandia began hundreds of millions of years ago. A 2021 study suggests the landmass is over a billion years old. This makes it twice as old as geologists previously believed. Originally, Zealandia was part of a much larger supercontinent called Gondwana. Between 83 and 79 million years ago, it broke away from Gondwana. Following this split, the landmass began to subside, or sink. By approximately 23 million years ago, the entire landmass may have been submerged under the ocean.

The physical structure of Zealandia is vast and mostly underwater. About 94% of the landmass remains submerged beneath the Pacific Ocean. The total area of Zealandia is approximately 4.9 million square kilometers. This makes it much larger than many other geological features. For example, it is six times the size of Madagascar, which is a large microcontinent. It is also larger than Greenland, the world's largest island, which is about 2.1 million square kilometers. Furthermore, Zealandia is larger than the Arabian Peninsula and the Indian subcontinent.

Today, only small portions of Zealandia rise above the sea level. New Zealand is the largest visible part of the landmass. New Caledonia is the second largest part. New Zealand makes up about 93.49% of the total land area. This includes the North Island, the South Island, and several outlying islands. The Chatham Islands and the Three Kings Islands are also part of this area. New Caledonia accounts for about 6.48% of the area. Other small territories, like Norfolk Island, make up the remaining tiny fractions.

Life has existed on Zealandia for a very long time. During the Jurassic period, about 180 million years ago, ancient forests grew there. These forests were closely related to modern kauri and Norfolk pine trees. Volcanic mud flows eventually buried these trees. Over time, silica replaced the wood to create fossils. You can still see these fossilized logs at Curio Bay today. While scientists once thought there were no native land mammals, a 2006 discovery changed that. A fossilized mammal jaw from the Miocene period was found in the Otago region.

Human activity is also connected to this submerged continent. About 5.4 million people live on the parts of Zealandia above water. Auckland is the largest city, housing about 1.7 million people. This is roughly one-third of the total population. The ocean surrounding Zealandia is also very useful for resources. It supports large inshore fisheries and contains important gas fields. The New Zealand Maui gas field is the largest known field. People also look for offshore minerals like ironsands and volcanic massive sulfides.

Understanding Zealandia helps us understand how our planet works. The name was proposed by Bruce Luyendyk in 1995. Mapping of the entire area was only recently concluded in 2023. The landmass has different names depending on the language used. In English, it is called Zealandia, a name related to New Zealand. In the Māori language, it is known as Te Riu-a-Māui. This translates to 'the hills, valleys, and plains of Māui.' This hidden continent shows us how much of our world is still being discovered.