Unlike any other rocky planet in the solar system, the earth’s surface is a giant puzzle, the pieces of which are constantly in motion. Each piece of the puzzle is a tectonic plate, enormous tartines from the planet’s crust, and a rigid disc of the squidgy-but-solid mantle below. These plates move at the same speed as your fingernails grow, bump against each other, slide side by side, and fall under and on top of each other – thus forming the face of the world.
Half a century ago, the theory of plate tectonics had just been accepted by an initially skeptical scientific community. Science was still in its infancy. As reported in a recent issue of Earth-Science Reviews, scientists can now precisely track the journeys of the Earth’s tectonic plates over the last billion years of their history.
Older computer-aided simulations usually only simulated the movements of the continents and showed them floating around on an undynamic blue background of the ocean like croutons floating around in soup. This time the scientists tried a new approach. They combined magnetic data that reveals the position of rocks relative to the magnetic poles millions of years ago with geological data that describes how the plates interact along their boundaries. The result is a high-fidelity simulation that models the migration of entire tectonic plates – continents, oceans, and all – and shows how they fraternize with one another with remarkable precision.
Similar meticulous reconstructions of plate tectonics have been carried out over the past decade, but only for limited geological time windows. This is the first time that this type of full plate tectonics reconstruction has been put together for an uninterrupted fifth of the Earth’s history.
This act of planetary time travel is of enormous importance to geoscientists, as plate tectonics controls or influences everything else on earth: it creates mountains, volcanoes, continents and oceans; it determines the distribution of life while blindly directing its development; By burying and erupting carbon, it regulates the world’s long-term climate.
“Many things that we look at and that interest us today depend on time cycles from 10 to 100 million years in plate tectonics,” said Andrew Merdith, geoscientist at Claude Bernard University Lyon 1 in France and lead author of the study in the United States. As we look back in time, more cycles are revealed that allow scientists to unravel the planetary-level processes that created the world we live in today.
“Plate tectonics is the really big picture that other things can be built into,” said Lucía Pérez-Díaz, a structural geologist and tectonics expert at Oxford University who was not involved in the work. And a lot has happened in the last billion years that this new recovery can help contextualize.
It includes the time when the earth was a giant snowball 700 million years ago; the distribution of complex animal species 540 million years ago; the largest mass extinction in the history of the earth 252 million years ago; the development of flowering plants 130 million years ago; the creation of the Himalayas 45 million years ago; and – precisely in the last geological second – the appearance of modern man.
Aside from its scientific applications, animation also resonates with humans on a visceral level.
“It’s pretty hypnotic,” said Dr. Pérez-Díaz, “for me too, and I see her all the time.”
“A lot of people, when they’re young, like dinosaurs and volcanoes and supercontinents and things like that,” said Dr. Merdith. “Maybe this is a bit of that childlike joy.”