The land mass that became Antarctica once sat next to the equator. Across Earth’s history, several supercontinents have broken up and reunited like the Backstreet Boys.
Our current seven continents and five oceans are the result of more than 3 billion years of planetary evolution. The tectonic plates cross on top of the semi-solid sludge of the Earth’s core.
But mapping the exact movements of those plates during all that time is challenging; existing models are often piecemeal, spanning only a few million years, or focusing on continental or oceanic changes, not both.
Now, for the first time, a group of geologists offers an easily digestible look at 1 billion years of plate tectonic motion.
The geoscientists, from the University of Sydney, have been constructing for four years how land masses and oceans have changed over the past billion years. As part of a recent study, they animated the changes in the short video below.
The animation shows green continents flying back and forth across oceans, represented in white. The Ma at the top of the video is 1 million geologists – so 1 000 Ma is 1 billion years ago. The different color lines represent different types of boundaries between tectonic plates: Blue-purple lines represent divergent boundaries, where plates are divided apart; red triangles indicate converging boundaries, where plates move together; and gray-green curves show boundaries of transformation, where plates move sideways past each other.
“These plates move with the rapid growth of nails, but if a billion years are summed up in 40 seconds, an enchanting dance is revealed,” said Sabin Zahirovic, a University of Sydney geologist who co-authored the new study. wrote, said in a press release.
Building a better model of the earth’s plates
The Earth formed 4.4 billion years ago, and after that it has cooled enough to form a solid crust with individual plates about 1.2 billion years later.
Today, one can imagine the planet as a chocolate truffle – a viscous centerpiece in a hardened shell. The center consists of a semi-solid 1800-mile mantle that surrounds a super-warm core. The top layer – only about 21 kilometers thick – is the crust, which is fragmented into tectonic plates that fit together.
These plates surf on top of the mantle and move around as warmer, less dense material rises from deep in the earth to the crust, and colder, denser material sinks to the core.
Geologists can compile a picture of what plates were hundreds of millions of years ago by analyzing the paleomagnetic data. When lava cools at the intersection of two tectonic plates, some of the rocks contain magnetic minerals that correspond to the directions of the Earth’s magnetic poles when the rock solidified. Even after the plates in which these rocks moved, researchers can study the magnetic alignment to find out where the natural magnets existed on the world map in the past.
Using paleomagnetics and current data from the tectonic plate, the study authors were able to create the most thorough map of each plate’s journey from 1 billion years ago to the present.
“Simply put, this complete model will help explain how our home, planet Earth, became habitable for complex beings,” Dietmar Müller, a co-author of the study, said in a press release.
Of course, the puzzle of the Earth’s continents did not stop moving. For example, the Pacific Ocean is shrinking year by year. The Atlantic Ocean, meanwhile, is expanding, pushing the Americas away from Africa and Europe.
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