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  • Breaking up is hard to do.

  • Sometimes, it feels like it goes on forever...days...weeks...months...millions of years?

  • Just ask Pangaea.

  • Plate tectonics.

  • It's not your fault if you take it for granted.

  • The concept that the Earth's crust moves around, rubs together, and pulls apart seems obvious now.

  • I mean just look at it.

  • But as recently as 50 years ago, thinking the continents had ever actually moved from their current locations would have gotten you laughed out of any serious scientific meeting.

  • The notion of moving continents all started with Alfred Wegener.

  • He noticed the continents appeared to fit together, almost perfectly, like a jigsaw puzzle.

  • And if they used to fit together, that means they must have somehow moved apart.

  • This led him to introduce a new idea: continental drift.

  • The snug fit of coastlines wasn't the only evidence that the continents were all once joined together in a giant landmass, all nice and cozy.

  • Wegener noticed fossils of certain animals had been found in Antarctica, India, and Africa.

  • How did the same animal end up all over the world?

  • Before, geologists thought land bridges had connected the continents, and were now submerged or eroded away.

  • Or else, they swam.

  • Remains of an ancient fern had also been found on five continents.

  • And ferns definitely can't swim.

  • It just didn't make sense.

  • That wasn't all.

  • The same types of rocks and mountains lined up continuously between continents.

  • It was a convincing body of evidence suggesting the continents moved around during Earth's history.

  • So obviously Wegener was celebrated and awarded for this brilliant idea, right?

  • More like the opposite.

  • One paleontologist called his theory "Germanic pseudoscience".

  • He was ridiculed around the world for his "delirious ravings."

  • The reason for all the hate was no one could see how continents might move.

  • Did the rotation of the Earth create enough centrifugal force to move them?

  • Was it the tides?

  • These forces weren't strong enough to move entire continents.

  • Wegener was never able to convince other scientists before he died on an expedition to Greenland in 1930 at only 50 years old.

  • He never knew the fate of his ideas.

  • In 1929, Arthur Holmes showed thermal convection in the mantle could create enough of a current to move the continental crust on top of it, an idea he originally got from Wegener.

  • In 1962, geologist Harry Hess found a strange magnetic pattern along a seafloor ridge.

  • Earth's magnetic field has flipped hundreds of time over the planet's history.

  • Magnetic minerals deep in the Earth, in hot magma, preserved this magnetic fingerprint as they cooled and hardened into rock.

  • Just like planetary tree rings, geologists could analyze the rock on either side of the ridge to retrace its history.

  • The seafloor was spreading apart at these ridges, where new rock was oozing up from the hot mantle.

  • Geologists finally had proof that earth's crust wasn't static.

  • It was constantly changing.

  • They're even moving right now.

  • Can't you tell?

  • Probably not.

  • Every year, the spreading at the Mid-Atlantic ridge pushes the Eurasian plate and North American plate just 2.5 centimeters farther apart.

  • But over millions of years, that really adds up.

  • Spreading between plates also happens on land.

  • The African plate and the Arabian plate are actually splitting the continent in two.

  • These deep rift valleys will eventually become an ocean and create a new separate African landmass.

  • The "Ring of Fire" is where denser oceanic crust is moving underneath the less dense continental crust.

  • 90% of the world's earthquakes and most major volcanoes occur along this margin.

  • Monstrous eruptions and destructive earthquakes change our world everyday and influence the lives of humans all over it.

  • Just like the surface of our dynamic planet, the story of plate tectonics shows us it can take a little while before earth-shaking ideas change the world.

  • If you catch my drift.

  • Stay curious!

Breaking up is hard to do.

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How Do We Know Plate Tectonics Is Real?

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    Liang Chen posted on 2019/05/28
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