Zealandia is a long, narrow microcontinent that is mostly submerged in the South Pacific Ocean.

A microcontinent is a landmass that has broken off from a main continent. Zealandia broke off from Antarctica about 100 million years ago, and then from Australia about 80 million years ago.

Zealandia is about half the size of Australia, but only 7 percent of it is above sea level. Most of that terrestrial land makes up the two large islands of the country of New Zealand, the North Island and the South Island. Stewart Island, just south of the South Island, and many smaller islets are also a part of Zealandia. New Caledonia, a collection of islands governed by France, makes up the northern tip of Zealandia.

Zealandia generally enjoys a mild, temperate climate. Its largest islands have glaciers, the largest being Tasman Glacier on the South Island. Activity from the last glacial period also carved out many fjords and valleys. The tropical climate of New Caledonia, on the other hand, has more in common with Oceania and the South Pacific.

Volcanic Activity

Zealandia is a very tectonically active region. Part of the microcontinent is on the Australian plate, while the other part is on the Pacific plate.

The northern part of Zealandia is very volcanic. There are six major areas with active volcanoes, the largest being the Taupo Volcanic Zone on the North Island. Geothermal activity caused by the interaction of the Australian and Pacific plates also means there are many natural geysers and hot springs scattered throughout Zealandia.

Both the North and South Islands have volcanic mountain ranges running through their centers. The North Island is dominated by the North Island Volcanic Plateau, while the primary mountain range of the South Island is the Southern Alps. Both mountain ranges are slowly getting higher through a process called tectonic uplift.

Underwater Zealandia

The submerged part of Zealandia is rich in mineral deposits, although New Zealand's government strictly controls undersea mining activity. There are also many natural gas fields scattered throughout Zealandia. The Maui natural gas field in the Tasman Sea is the largest.

Underwater Zealandia is of value to science as well as business. During glacial periods, sea levels fell, and more of Zealandia was above water. Zealandia's submerged fossils provide valuable clues to life during those time periods.

Zealandia
Most of Zealandia lies underwater.

Exclusively Zealandia
The microcontinent of Zealandia helps determine New Zealand's Exclusive Economic Zone, or the offshore area around a country. A country may use any natural resources, such as oil or fish, in its EEZ without permission from another organization. New Zealand's EEZ is about 4.3 million square kilometers (2.7 million square miles), more than 15 times the amount of land above ground.

Noun

all weather conditions for a given location over a period of time.

Noun

one of the seven main land masses on Earth.

Noun

long, narrow ocean inlet between steep slopes.

Noun

remnant, impression, or trace of an ancient organism.

Noun

remnant, impression, or trace of an ancient organism.

Noun

heat energy generated within the Earth.

Noun

natural hot spring that sometimes erupts with water or steam.

glacial period
Noun

time of long-term lowering of temperatures on Earth. Also known as an ice age.

Noun

mass of ice that moves slowly over land.

hot spring
Noun

small flow of water flowing naturally from an underground water source heated by hot or molten rock.

Noun

body of land surrounded by water.

microcontinent
Noun

a type of large continental island.

mineral
Noun

inorganic material that has a characteristic chemical composition and specific crystal structure.

mining
Noun

process of extracting ore from the Earth.

mountain range
Noun

series or chain of mountains that are close together.

Noun

type of fossil fuel made up mostly of the gas methane.

Oceania
Noun

region including island groups in the South Pacific.

plate tectonics
Noun

movement and interaction of the Earth's plates.

Polynesia
Noun

island group in the Pacific Ocean between New Zealand, Hawaii, and Easter Island.

Noun

base level for measuring elevations. Sea level is determined by measurements taken over a 19-year cycle.

submerge
Verb

to put underwater.

temperate
Adjective

moderate.

terrestrial
Adjective

having to do with the Earth or dry land.

tropical
Adjective

existing in the tropics, the latitudes between the Tropic of Cancer in the north and the Tropic of Capricorn in the south.

uplift
Noun

elevation of the Earth's surface due to tectonic or other natural activity.

valley
Noun

depression in the Earth between hills.

volcanic
Adjective

having to do with volcanoes.

Noun

a microcontinent that broke off from Australia about 80 million years ago. Zealandia is almost totally underwater.