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42-487: Zealandia (pronounced / z iː ˈ l æ n d i ə / ), also known as Te Riu-a-Māui ( Māori ) or Tasmantis (from Tasman Sea ), is an almost entirely submerged mass of continental crust in Oceania that subsided after breaking away from Gondwana 83–79 million years ago. It has been described variously as a submerged continent , continental fragment , and microcontinent . The name and concept for Zealandia

84-696: A megalodon , an extinct shark, was also found by researchers. In 1876, the first telegraph cable connecting Australia and New Zealand was laid in the Tasman Sea. The telegraph cable was made obsolete in 1963 when the Commonwealth Pacific Cable , New Zealand's first international telephone cable, was completed. Moncrieff and Hood were the first to attempt a trans-Tasman crossing by plane in January 1928. The aviators were never seen or heard of again. The first successful flight over

126-518: A billion years ago and sources from an expanded-Ur continent between 3.5 and 2 billion years ago. The breakup of Gondwana formed Northern Zealandia. Zealandia underwent extension resulting from east to northeast-directed rollback of west to southwest-dipping subduction of the Pacific Plate . which terminated between 95 million to 85 million years ago. After 85 million years ago Zealandia separated from Australia through seafloor spreading of

168-699: Is 286,660.25 km (110,680.14 sq mi). Of this, New Zealand comprises the overwhelming majority, at 267,988 km (103,471 sq mi, or 93.49%) that includes the mainland ( North Island and South Island ), nearby islands, and most outlying islands , including the Chatham Islands , the New Zealand Subantarctic Islands , the Solander Islands , and the Three Kings Islands (but not

210-575: Is 67% the mass of the Earth. It has a thickness of 2,900 kilometres (1,800 mi) making up about 84% of Earth's volume. It is predominantly solid, but in geological time it behaves as a viscous fluid . Partial melting of the mantle at mid-ocean ridges produces oceanic crust , and partial melting of the mantle at subduction zones produces continental crust . Mercury has a silicate mantle approximately 490 kilometers (300 miles) thick, constituting only 28% of its mass. Venus 's silicate mantle

252-525: Is a marginal sea of the South Pacific Ocean , situated between Australia and New Zealand . It measures about 2,000 km (1,200 mi) across and about 2,800 km (1,700 mi) from north to south. The sea was named after the Dutch explorer Abel Janszoon Tasman , who in 1642 was the first known person to cross it. British explorer Lieutenant James Cook later extensively navigated

294-534: Is also substantially larger than the Arabian Peninsula (3,237,500 km or 1,250,000 sq mi), the world's largest peninsula , and the Indian subcontinent (4,300,000 km or 1,700,000 sq mi). Due to these and other geological considerations, such as crustal thickness and density, some geologists from New Zealand, New Caledonia, and Australia have concluded that Zealandia fulfills all

336-485: Is approximately 2,800 kilometers (1,700 miles) thick, constituting around 70% of its mass. Mars 's silicate mantle is approximately 1,600 kilometers (990 miles) thick, constituting ~74–88% of its mass, and may be represented by chassignite meteorites. Uranus and Neptune 's ice mantles are approximately 30,000 km thick, composing 80% of both masses. Jupiter 's moons Io , Europa , and Ganymede have silicate mantles; Io's ~1,100 kilometers (680 miles) silicate mantle

378-678: Is at the northern end of the ancient continent, while New Zealand rises at the plate boundary that bisects it. These land masses constitute two outposts of the Antarctic flora , featuring araucarias and podocarps . At Curio Bay , logs of a fossilized forest closely related to modern kauri and Norfolk pine can be seen that grew on Zealandia approximately 180 million years ago during the Jurassic period, before it split from Gondwana. The trees growing in these forests were buried by volcanic mud flows and gradually replaced by silica to produce

420-789: Is diverted west in the Subtropical Front which collides with the western moving Subantarctic front of the Antarctic Circumpolar Current . The East Australian Current sheds eddies on its way south that move south-westward with some known as the Tasman Leakage making it as far westward as the Indian Ocean. A deep-sea research ship, the RV Tangaroa , explored the sea and found 500 species of fish and 1300 species of invertebrates. The tooth of

462-491: Is overlain by a volcanic crust, Ganymede's ~1,315 kilometers (817 miles) thick silicate mantle is overlain by ~835 kilometers (519 miles) of ice, and Europa's ~1,165 kilometers (724 miles) km silicate mantle is overlain by ~85 kilometers (53 miles) of ice and possibly liquid water. The silicate mantle of the Earth's moon is approximately 1300–1400 km thick, and is the source of mare basalts . The lunar mantle might be exposed in

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504-559: Is six times the area of the next-largest microcontinent, Madagascar , and more than half the area of the Australian continent . Zealandia is more than twice the size of the largest intraoceanic large igneous province (LIP) in the world, the Ontong Java Plateau (approximately 1,900,000 km or 730,000 sq mi), and the world's largest island, Greenland (2,166,086 km or 836,330 sq mi). Zealandia

546-411: Is the largest part of Zealandia that is above sea level, followed by New Caledonia . Mapping of Zealandia concluded in 2023. With a total area of approximately 4,900,000 km (1,900,000 sq mi), Zealandia is substantially larger than any features termed microcontinents and continental fragments. If classified as a microcontinent, Zealandia would be the world's largest microcontinent. Its area

588-475: Is thinner than usual, approximately 20 km (12 mi) thick, and consequently, they do not float so high above Earth's mantle as that of most landmasses. About 25 million years ago, the southern part of Zealandia (on the Pacific Plate ) began to shift relative to the northern part (on the Indo-Australian Plate ). The resulting displacement by approximately 500 km (310 mi) along

630-627: Is widespread across Zealandia, but on present land generally it is of low volume apart from the huge mid to late Miocene shield volcanoes that developed the Banks and Otago Peninsulas . In addition, it took place continually in numerous limited regions all through the Late Cretaceous and the Cenozoic . Some of its causes remain in dispute perhaps because of data gaps. During the Miocene ,

672-749: The Alpine Fault is evident in geological maps. Movement along this plate boundary also has offset the New Caledonia Basin from its previous continuation through the Bounty Trough . Compression across the boundary has uplifted the Southern Alps , although due to rapid erosion their height reflects only a small fraction of the uplift. Farther north, subduction of the Pacific Plate has led to extensive volcanism, including

714-864: The Cato , Elizabeth , and Middleton reefs ( Coral Sea Islands Territory ) with 5.25 km (2.03 sq mi). As of 2024, the total human population of Zealandia is approximately 5.4 million people. The largest city is Auckland with about 1.7 million people; roughly one-third of the total population of the continent. [REDACTED] Africa [REDACTED] Antarctica [REDACTED] Asia [REDACTED] Australia [REDACTED] Europe [REDACTED] North America [REDACTED] South America [REDACTED] Afro-Eurasia [REDACTED] Americas [REDACTED] Eurasia [REDACTED] Oceania 40°S 170°E  /  40°S 170°E  / -40; 170 Tasman Sea The Tasman Sea

756-511: The Coral and Tasman seas until this ceased 52 million years ago. Shortening on an active convergent northern margin of Zealandia occurred mainly between 45 and 35 million years ago. This was followed by the opening of the backarc basins of the southwest Pacific and the migration of the Tonga and Kermadec Trenchs to the east. Shear extrusion followed between 23.3 million to 5 million years ago with

798-616: The Coromandel and Taupo Volcanic Zones . Associated rifting and subsidence has produced the Hauraki Rift and more recently, the Whakatane Graben and Wanganui Basin. Volcanism on Zealandia has taken place repeatedly in various parts of the continental fragment before, during, and after it rifted away from the supercontinent Gondwana . Although Zealandia has shifted approximately 6,000 km (3,700 mi) to

840-514: The Great South Basin were issued in 2007. Offshore mineral resources include ironsands , volcanic massive sulfides and ferromanganese nodule deposits. GNS Science recognises two names for the landmass. In English, the most common name is Zealandia , a latinate name for New Zealand; the name was coined in the mid-1990s and became established through common use. In the Māori language ,

882-586: The Kermadec Islands or Macquarie Island ( Australia ), which are parts of the rift). New Caledonia and the islands surrounding it comprise some 18,576 km (7,172 sq mi or 6.48%) and the remainder is made up of various territories of Australia including the Lord Howe Island Group ( New South Wales ) at 56 km (22 sq mi or 0.02%), Norfolk Island at 35 km (14 sq mi or 0.01%), as well as

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924-750: The East Australian Current continues south in the western Tasman a branch flows east called the Tasman Front towards the north of New Zealand with most continuing eastward above New Zealand into the South Pacific Ocean. It transpires that while predominantly the location of westerly wind stress is a factor in how far north the formation of the Tasman Front occurs, so is the presence of the New Zealand land mass, as

966-684: The New Zealand Alpine Fault rupture and a southwestward extension of the Campbell Plateau relative to the Challenger Plateau . Southeast Indian Ocean Ridge expansion movement completely separated Zealandia from the Antarctic at about 10 million years ago. In the last 5 million years Zealandia has been generally subsiding owing to the Pacific Plate subducting westward and retreating eastward. New Caledonia

1008-843: The Northeast From the South East Rock to the north point of Three Kings Islands ( 34°10′S 172°10′E  /  34.167°S 172.167°E  / -34.167; 172.167 ), thence to North Cape in New Zealand. On the East On the Southeast A line running from South West Cape , Stewart Island, through the Snares (48°S, 166°30'E) to North West Cape, Auckland Island ( 50°30′S 166°10′E  /  50.500°S 166.167°E  / -50.500; 166.167 ), through this island to its southern point. On

1050-475: The South A line joining the southern point of Auckland Island ( 50°55′S 166°0′E  /  50.917°S 166.000°E  / -50.917; 166.000 ) to South East Cape, the southern point of Tasmania. The Tasman Sea's midocean ridge developed between 85 and 55 million years ago as Australia and Zealandia broke apart during the breakup of supercontinent Gondwana . It lies roughly midway between

1092-591: The Tasman Sea in the 1770s during his three voyages of exploration. The Tasman Sea is informally referred to in both Australian and New Zealand English as the Ditch ; for example, " crossing the Ditch " means travelling to Australia from New Zealand, or vice versa. The diminutive term "the Ditch" used for the Tasman Sea is comparable to referring to the North Atlantic Ocean as "the Pond". The south of

1134-526: The authors presented geological and ecological evidence in support of their thesis. In 2017, a team of eleven geologists from New Zealand, New Caledonia, and Australia concluded that Zealandia fulfills all the requirements to be considered a submerged continent , rather than a microcontinent or continental fragment . This verdict was widely covered in the news media . The younger Zealandia rocks have evidence of origins from early Gondwana formations of 500 to 700 million years ago, Rodinia formations about

1176-527: The continental margins of Australia and Zealandia. Much of Zealandia is submerged, so the ridge runs much closer to the Australian coast than New Zealand's. The Tasman Sea features a number of midsea island groups, quite apart from coastal islands located near the Australian and New Zealand mainlands: The East Australian Current that commences its flow southwards in the tropics of the Coral Sea, near

1218-494: The east coast to South East Cape , the southern point of Tasmania. On the North The parallel of 30°S from the Australian coast eastward as far as a line joining the east extremities of Elizabeth Reef and South East Rock ( 31°47′S 159°18′E  /  31.783°S 159.300°E  / -31.783; 159.300 ) then to the southward along this line to the South East Rock [an outlier of Lord Howe Island ]. On

1260-465: The eastern coast of Australia is the most energetic circulation feature in the south western Pacific Ocean and is a primary means of heat transport from the tropics to the middle latitudes between Australia and New Zealand. The East Australian Current is a return of the westward-flowing Pacific Equatorial Current (Pacific South Equatorial Current ). At the juncture between the Tasman and Coral seas while

1302-481: The fossils now exposed by the sea. As sea levels drop during glacial periods, more of Zealandia becomes a terrestrial environment rather than a marine environment. Originally, it was thought that Zealandia had no native land mammal fauna, but the discovery in 2006 of a fossil mammal jaw from the Miocene in the Otago region demonstrates otherwise. The total land area (including inland water bodies ) of Zealandia

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1344-528: The landmass is named Te Riu-a-Māui , meaning 'the hills, valleys, and plains of Māui '. The Zealandia continent is largely made up of two nearly parallel ridges, separated by a failed rift , where the rift breakup of the continent stops and becomes a filled graben . The ridges rise above the sea floor to heights of 1,000–1,500 m (3,300–4,900 ft), with a few rocky islands rising above sea level . The ridges are continental rock, but are lower in elevation than normal continents because their crust

1386-541: The latter of which contains most of the Median Batholith crust. These two features are separated by the Alpine Fault and Kermadec Trench and by the wedge-shaped Hikurangi Plateau , and they are moving separately from each other. The case for Zealandia being a continent in its own right has been argued in the Nick Mortimer and Hamish Campbell book Zealandia: Our continent revealed (2014), in which

1428-564: The northern section of Zealandia ( Lord Howe Rise ) might have slid over a stationary hotspot , forming the Lord Howe Seamount Chain . It has been suggested that Zealandia may have played an important part in the origin of the Pacific Ocean's volcanic Ring of Fire . Occasionally, Zealandia is divided into two regions by scientists: North Zealandia (or Western Province); and South Zealandia (or Eastern Province),

1470-554: The northwest with respect to the underlying mantle from the time when it rifted from Antarctica , recurring intracontinental volcanism exhibits magma composition similar to that of volcanoes in previously adjacent parts of Antarctica and Australia. Large volume magmatism occurred in two periods, being in the Devonian (370 to 368 million years ago) and the Early Cretaceous (129 to 105 million years ago). This volcanism

1512-481: The requirements to be considered a continent rather than a microcontinent or continental fragment. Geologist Nick Mortimer commented that if it were not for the ocean level, it would have been recognised as such long ago. Zealandia supports substantial inshore fisheries and contains gas fields, of which the largest known is the New Zealand Maui gas field , near Taranaki . Permits for oil exploration in

1554-427: The sea is passed over by depressions going from west to east. The northern limit of these westerly winds is near to 40°S . During the southern winter, from April to October, the northern branch of these winds from the west changes its direction toward the north and goes up against trade winds . Hence, the sea receives frequent winds from the southwest during this period. In the Australian summer (from November to March),

1596-456: The sea was accomplished by Charles Kingsford Smith and Charles Ulm later that year. The first person to row solo across the sea was Colin Quincey in 1977. The next successful solo crossing was completed by his son, Shaun Quincey, in 2010. Mantle (geology) The Earth's mantle is a layer of silicate rock between the crust and the outer core . Its mass of 4.01 × 10 kg

1638-432: The southern branch of the trade winds goes up against west winds and produces further wind activity in the area. The Tasman Sea is 2,250 km (1,400 mi) wide and has an area of 2,300,000 km (890,000 sq mi). The maximum depth of the sea is 5,943 m (19,498 ft). The base of the sea is made up of globigerina ooze. A small zone of pteropod ooze is found to the south of New Caledonia and to

1680-730: The southern extent of 30°S , siliceous ooze can be found. The International Hydrographic Organization defines the limits of the Tasman Sea as: On the West A line from Gabo Island (near Cape Howe , 37°30'S) to the northeast point of East Sister Island (148°E), thence along the 148th meridian to Flinders Island ; beyond this island a line running to the eastward of the Vansittart Shoals to [Cape] Barren Island , and from Cape Barren (the easternmost point of [Cape] Barren Island) to Eddystone Point (41°S) in Tasmania, thence along

1722-838: The top of New Zealand defines the furtherest south that the Tasman Front can be split off by the westerly winds. A boundary current called the East Auckland Current goes down the west coast of the North Island and further south the East Cape Current, that has been diverted towards the South Island by the shapes of the Lord Howe Rise and southern east coast of the North island continues to the south. The East Australian Current south of Tasmania also

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1764-468: Was proposed by Bruce Luyendyk in 1995, and satellite imagery shows it to be almost the size of Australia. A 2021 study suggests Zealandia is over a billion years old, about twice as old as geologists previously thought. By approximately 23 million years ago, the landmass may have been completely submerged. Today, most of the landmass (94%) remains submerged beneath the Pacific Ocean . New Zealand

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