Image Credit:Brett Ryder
ASIA is torn in two. The Atlantic and Pacific oceans are swallowed. Where once there were beaches, great mountain ranges judder into the skies, fusing together a scatter of separate land masses into one mighty new supercontinent. Call it… Aurica.
That’s what João Duarte calls it, anyway. A geoscientist at the University of Lisbon, Portugal, he has his own distinct vision of how Earth may look 250 million years from now. He joins a band of fortune tellers gazing into the distant future, all with different ideas about how and where the next supercontinent will form, and what cataclysms might strike along the way.
The answer will determine Earth’s future climate and prospects for sustaining life. But getting it right requires grappling with a machine whose workings we still understand only imperfectly: that of plate tectonics.
Earth’s surface is clad in rigid rock plates – together called the lithosphere – formed of surface crustal rock laminated on to hard cold mantle rocks. Given their rigidity, it is surprising that these plates don’t simply lock together, unmoving. And indeed, until about 50 years ago geologists thought that Earth’s land masses were fixed, despite German geophysicist Alfred Wegener having proposed the idea of continental drift in 1915.
The creation and destruction of ocean basins makes plate motion possible. Plates move apart at mid-ocean ridges, where molten rock rises and cools to form hard, dense basalt. They move together at subduction zones, where old ocean lithosphere plunges under a neighbouring plate. As it penetrates the warmer, softer mantle beneath, it causes earthquakes and feeds volcanoes.
Magnetic signals recorded in sea-floor rocks,