Brace yourself for surprising plate tectonics facts.

The theory of plate tectonics—that Earth’s surface is shaped and affected by deep geological plates moving around—is really only about fifty years old in its current form. For what now seems like (sorry) bedrock knowledge about why things like earthquakes happen, that isn’t terribly old at all. Jerry Lee Lewis had been singing “Whole Lotta Shakin’ Goin’ On” for over a decade before earth science had a unifying theory on what all that shaking was about.

Getting to that unified theory took decades of heated exchanges between “mobilists” and “fixists,” competing hypotheses about what was inside the Earth’s mantle, and evolving technologies that helped science to fill in the gaps in our understanding about what's going on below the surface.

In its Shaking Up Earth theme, Century of Science presents this history and explains why plate tectonics continues to shift our understanding of our planet. The only planet we know to have plate tectonics, by the way.

The Earth's plate tectonics are on full display in Iceland, which sits atop both the Eurasian and the North American plates. The line where they meet, the Mid-Atlantic Ridge, is visible (and walkable) in Þingvellir National Park, the only place on the planet to see it above sea level.

How did scientists finally prove the theory of plate tectonics? By getting a bit of help from a World War II workhorse: the magnetometer. Developed out of earlier efforts to create sensitive detection of metal underwater—like the kind of metal that would be wrapped around an enemy submarine lurking deep below the waters—scientists used the magnetometer to show the ocean floor was spreading out.