Is zealandia 8th continent?? WITH EXPLANITION
Answers
Answer:
About 3,500 feet under the south Pacific sits a piece of land 2 million square miles in size — about half as big as Australia.
But scientists can't agree on whether this submerged land mass, called Zealandia, is a continent or not. A team of geologists declared it one in 2017, but not all researchers are convinced.
"It's not like a mountain, country, or planet. There is no formal body to approve a continent," Nick Mortimer, a geologist from New Zealand's GNS Science who led 2017 group, told Insider.
While the definition of a continent is contentious, Mortimer's group suggested that a continent should have clearly defined boundaries, occupy an area greater than 386,000 square miles (1 million square kilometers), be elevated above the surrounding ocean crust, and have a continental crust thicker than that oceanic crust.
Zealandia meets all those stipulations.
"If you were to drain the oceans, Zealandia would stand out as a well-defined, high-standing plateau above the ocean floor," Mortimer said.
He considers it "the thinnest, most submerged and smallest continent."
The problem, however, was that until recently, the oldest crust and rock ever sampled from Zealandia was just 500 million years old, whereas all the other continents contain crust that is 1 billion years old or more. But a recent study found that part of the submerged continent is twice as old as geologists previously thought, which could boost Mortimer's argument.
"This new study ticks that final continental box," Rose Turnbull, a New Zealand geologist who co-authored the study, said in a press release. "There is no longer any doubt that we live on top of a continent."
Zealandia, a term geophysicist Bruce Luyendyk coined in 1995, is made up of New Zealand and a collection of submerged chunks of crust that broke off an ancient supercontinent called Gondwana about 85 million years ago.
About 94% of it is underwater — Zealandia sunk under the waves about 30 million to 50 million years after it broke off Gondwana. So it's a challenging land mass to study.
The geologists behind the recent research looked at 169 chunks of Zealandia granite, which were found under New Zealand's South and Stewart Islands. Granite forms when magma crystallizes deep within the Earth's crust.
By extracting microscopic crystals from the granite, the team was able to determine both the age of the crystals themselves and of the crust in which they formed. The results showed that crust was once part of another supercontinent known as Rodinia, which formed between 1.3 billion and 900 million years ago.
In other words, Zealandia's geologic history starts far earlier than 500 million years ago.