Unlike on every other rocky planet in the solar system, Earth’s surface is a giant jigsaw puzzle whose pieces are constantly on the move. Each puzzle piece is a tectonic plate, tremendous tartines made of the planet’s crust and a rigid slice of the underlying, squidgy-but-solid mantle. These plates move around at the same rate that your fingernails grow, bumping into, sliding next to and tumbling under and over each other — and in doing so, they sculpt the face of the world.
Half a century ago, the theory of plate tectonics had just been accepted by an initially skeptical scientific community. The science was in its infancy. Now, as reported in a recent issue of the journal Earth-Science Reviews, scientists are able to precisely recreate the journeys of Earth’s tectonic plates over the last billion years of its history.
Older computerized simulations tended to recreate the movements of the continents alone, showing them drifting about on an undynamic blue ocean background like croutons bobbing about in soup. This time around, the scientists tried a new approach. They combined magnetic data, which reveals the positions of rocks relative to the magnetic poles millions of years ago, with geological data describing how the plates interact along their boundaries. The result is a high-fidelity simulation, one that models the migration of entire tectonic plates — continents, oceans and all — showing how they fraternize with one another with remarkable precision.
In the past decade, similarly painstaking plate tectonics reconstructions have been made but only for limited windows of geologic time. This is the first time this type of full-blown plate tectonics reconstruction has been assembled for an uninterrupted fifth of Earth’s history.
This act of planetary time travel is of vast importance to geoscientists, because plate tectonics controls or influences everything else that happens on Earth: It makes mountains, volcanoes, continents and oceans; it determines the distribution of life while blindly guiding its evolution; by both burying carbon and erupting it, it regulates the world’s long-term climate.
“A lot of things we look at and care about in the present day are dependent on 10- to 100-million-year time cycles in plate tectonics,” said Andrew Merdith, a geoscientist at the Claude Bernard University Lyon 1 in France and the study’s lead author. By looking further back in time, more cycles are revealed, allowing scientists to unravel the planetary-scale processes that made the world we live in today.
“Plate tectonics is that really big picture that you can put other things into,” said Lucía Pérez-Díaz, a structural geologist and tectonics expert at the University of Oxford who was not involved with the work. And a lot of things have happened in the past billion years that this new recreation can help contextualize.
It includes the time Earth was a giant snowball 700 million years ago; the proliferation of complex animal life 540 million years ago; the greatest mass extinction in Earth’s history 252 million years ago; the evolution of flowering plants 130 million years ago; the creation of the Himalayas 45 million years ago; and — right at the last geologic second — the appearance of modern humans.
Its scientific uses aside, the animation also resonates with people on a visceral level.
“It’s quite hypnotic,” Dr. Pérez-Díaz said, “even for me, and I see them all the time.”
“A lot of people when they’re young really like dinosaurs and volcanoes and supercontinents and things like that,” Dr. Merdith said. “So maybe this taps into a little bit of that childlike delight.”
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