0:00 The ground beneath your feet is moving right now, about as fast as your fingernails grow—maybe six inches a year, tops.0:08 And those six inches, over millions of years, can create a volcano, or trigger an earthquake, or raise a mountain range ten thousand feet high.0:19 It's just staggering!0:21 Last week on Quantum Wonders, we talked about gravity holding entire galaxies in this perfect, cosmic dance, and now you're telling me there's a similar, incredible dance happening right under our feet.0:36 That is the perfect way to frame it.0:39 It’s the theory of plate tectonics.0:41 And it's the story of how our planet is constantly, beautifully remaking itself.0:47 Okay, so break it down for me.0:50 "Tectonic plates." I've heard the term my whole life, but what are they, really?0:56 Are they like giant, rocky puzzle pieces?0:59 Exactly like that!1:00 The Earth’s entire outer shell—its crust—isn’t one solid, seamless piece.1:06 It’s broken into about a dozen giant, rigid plates and a bunch of smaller ones that all fit together.1:13 And these plates are just...1:15 floating?1:16 Floating on what?1:17 On the mantle!1:18 It's the layer right below the crust.1:21 The best way to picture it is to imagine a giant, planet-sized pot of incredibly thick, hot soup that’s been simmering for billions of years.1:32 A planet-sized pot of soup!1:34 I love it.1:35 The intense heat from the Earth's core makes the molten rock in the mantle rise, cool off near the surface, and then sink back down in these huge, slow-motion circular currents.1:48 And the plates are just along for the ride, like crackers floating on top of that soup!1:55 That’s the one!1:56 They're being pushed and pulled by these massive convection currents.2:01 Some move at less than an inch a year, while others, like the Pacific Plate, can book it at six inches a year.2:09 Wait—so what happens when these giant, continent-sized crackers bump into each other?2:16 That is where ALL the action is.2:18 You get three main types of fireworks.2:21 Sometimes they crash right into each other.2:24 A head-on collision!2:26 A very, very, VERY slow head-on collision.2:29 When two continental plates collide, the rock has nowhere to go but up.2:34 That's how we got the Himalayas.2:37 The Indian plate is still pushing into the Eurasian plate right now.2:42 So mountains are basically the planet's crumple zones.2:46 What else can happen?2:47 Sometimes, they pull apart.2:49 That's called a divergent boundary.2:52 Magma from the mantle rushes up to fill the gap, creating brand new crust.2:58 It's happening as we speak, right down the middle of the Atlantic Ocean.3:03 The Atlantic is actually getting wider every year?!3:07 By about an inch!3:08 And the third way is they slide past each other.3:12 That’s a transform boundary.3:14 Like the San Andreas Fault in California.3:17 Precisely.3:18 The plates try to slide, but their edges are jagged and they get stuck.3:23 Pressure builds and builds for years, decades, even centuries, and then— —they slip.3:30 That sudden release of energy is an earthquake.3:33 Wow.3:33 So earthquakes, volcanoes, mountains...3:36 it all comes back to the edges of these plates.3:40 It all comes back to the plate boundaries.3:43 Take a look at the Pacific Ocean.3:46 The edges of the enormous Pacific Plate are almost all active boundaries, rubbing up against other plates.3:54 Is that what they call the "Ring of Fire"?3:57 That's it.3:57 It's a nearly 25,000-mile-long horseshoe of volcanoes and earthquake sites that rims the entire Pacific Ocean.4:06 Something like ninety percent of the world's earthquakes happen along that one ring.4:12 All because this one giant plate is constantly crashing into, pulling away from, or sliding past its neighbors.4:20 All at the same time.4:22 It is the most geologically dynamic place on the entire planet.4:27 It's just so wild to think about.4:29 We walk around on this solid ground, but it's really just the thin, cool crust on top of a raging, boiling engine.4:38 An engine that has been running for billions of years.4:42 It’s what broke apart the supercontinent Pangaea into the continents we know today.4:48 It’s what built the mountains we climb and what carves out the oceans we cross.4:54 So the world map is just… a snapshot.4:57 A temporary arrangement.4:59 A very temporary arrangement, on a geological timescale.5:03 The forces are always at work.5:05 The world map is a verb, not a noun.5:08 So the ground isn't really solid ground at all.5:12 It's a promise that's always being broken and remade.5:16 I couldn't have said it better myself.5:18 It's the planet's living, breathing skin.
