Secrets of Earth’s sunken ‘lost continent’ revealed
The lost, underwater continent of Zealandia may have been used by animals and plants to cross continents 80 million years ago, research has found.
Zealandia, a mostly-submerged landmass in the South Pacific, was declared Earth’s newest continent earlier this year. Covering five million square kilometres (1.9 million square miles), it includes Lord Howe Island off Australia’s east coast, New Caledonia and New Zealand.
An international team of scientists found fossilised remains and evidence of large-scale tectonic plate shifts as part of one of the first extensive surveys of the region.
‘The discovery of microscopic shells of organisms that lived in warm shallow seas, and spores and pollen from land plants, reveal that the geography and climate of Zealandia was dramatically different in the past,’ said expedition co-chief scientist Professor Gerald Dickens of Rice University in Houston, Texas.
Expedition scientists drilled deep into the seabed at six sites in water depths of more than 1,250 meters (4,101 feet). They took 2,500 meters (8,202 feet) of sediment cores from layers that show how the geography and climate of Zealandia have changed over the last 70 million years.
‘More than 8,000 specimens were studied, and several hundred fossil species were identified,’ said Professor Dickens.
He added that the significant new fossil discoveries prove that Zealandia was not always as deep beneath the waves as it is today. Zealandia, which is mostly submerged beneath the South Pacific, was once part of the Gondwana super-continent but broke away some 75 million years ago.
In a paper published in the Geological Society of America’s Journal GSA Today in February, researchers made the case that it should be considered a new continent.
They said it was a distinct geological entity that met all the criteria applied to Earth’s other continents. These criteria include elevation above the surrounding area, distinctive geology, a well-defined area and a crust much thicker than that found on the ocean floor.
The newly extracted sediment cores show how the continent experienced tectonic and ecological change across millions of years.
‘Zealandia, a sunken continent long lost beneath the oceans, is giving up its 60 million-year-old secrets through scientific ocean drilling,’ said project co-director Jamie Allan.
‘This expedition offered insights into Earth’s history, ranging from mountain-building in New Zealand to the shifting movements of Earth’s tectonic plates to changes in ocean circulation and global climate.’
The new discoveries reveal new details about the formation of the ‘Pacific Ring of Fire’ – an active seafloor zone along the perimeter of the Pacific Ocean.
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