Welcome to Quantum Magazine's podcast. Each episode, we bring you stories about developments in science and mathematics. I'm Susan Vallett. In 2016, geochemists

Jonas Tush and Karsten Munker hammered 1,000 pounds of rock from the

Australian outback.

They air freighted it home to Cologne, Germany, and then spent five years sawing, crushing,

dissolving and analyzing it.

Now they've coaxed from those rocks a secret hidden for eons.

The era when plate tectonics began. That's next.

Explore other science mysteries in the Quanta book Alice and Bob Meet the Wall of Fire,

published by the MIT Press, available now at Amazon.com, Barnes & Noble.com, or your local bookstore.

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Earth's fractured surface of rigid, interlocking plates is unique in the solar system.

Scientists increasingly connect it to our planet's

other special features, such as its stable atmosphere, protective magnetic field, and menagerie of

complex life. But geologists have long debated exactly when Earth's crust broke into plates in the first place.

Competing hypotheses span from the first billion years of the planet's four and a half billion

year history to sometime in the last billion years. Those estimates have wildly different

implications for how plate tectonics affects everything else on Earth. The spreading,

smashing, and plunging of tectonic plates shapes far more than just geography. The recycling of

Earth's surface helps to regulate its climate, while the building of continents and mountains

pumps vital nutrients into the ecosystem.

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