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Rock Cycle

5 minutes

[whirring]

(Describer) A machine burns lines into wood, drawing rectangles that form the letters MIT.

(Describer) Different rocks sit in a line.

(female narrator) I bet you thought rocks are just rocks, right?

(Describer) Three people are dressed as rocks.

Nope. There are three major types of rocks: sedimentary, igneous, and metamorphic. The coolest thing is that each one has the ability to change into the other kind.

(Describer) They shake their heads.

Huh? How is that possible?

[rock guitar plays]

(Describer) In fast-motion, someone writes on a whiteboard the title: The Rock Cycle. Drawings of lightning, stars and a rock are added.

[record scratch]

(male narrator) Sedimentary, metamorphic, and igneous rocks change into each other in a process we call...

(Describer) The people dressed as rocks pretend to play instruments.

[rock music]

No, not that kind of rock. This kind of rock.

[rock music]

(Describer) They hold actual rocks and shake them.

Yeah, that's more like it. The first type of rock we'll talk about is sedimentary. On the Earth's surface, wind and water break down rock into tiny pieces. Those pieces might collect in a riverbed, on a flood plain, in sand dunes, or collect on the ground. Over time, layers of these fragments build up and weigh down on one another. Eventually, they get fused together to form sedimentary rocks. If you look closely, you can still see pieces of the original rocks or sediment that were bound together.

(female narrator) Let's do a demo. We'll use jelly beans. Each flavor of jelly bean represents a rock or mineral

broken down by wind and water through erosion. We'll add jelly beans to some honey and corn starch. They're the bonding agents to hold pieces together, like glue for rocks. A little time and pressure turns our jelly bean pieces of sediment into a brand-new rock.

(male narrator) If you apply heat and pressure, it becomes a metamorphic rock. Metamorphic rock may form by friction of the Earth's shifting crust, pressure deep within the Earth, or even radioactive decay. The heat and pressure cause the rock structure to change, taking on a new form. Though it's changed, you can see structures of its original components.

(female narrator) Let's turn our sedimentary jelly bean rock into a metamorphic one with heat and pressure.

(Describer) It’s wrapped in foil.

To add pressure, we'll put this heavy pot on top. For heat, we'll bake it for 30 minutes. After it's cooled, our jelly bean rock has formed a more solid unit. You can still see the individual pieces of candy, but the structure has fundamentally changed.

(male narrator) The third type of rock is igneous. When rocks get superheated deep within the Earth,

they melt and form a liquid called magma. If magma moves up in the Earth's crust, it begins to cool. Igneous rocks have a uniform structure, but different properties, depending on whether they cooled on the Earth's surface or within the crust.

(female narrator) To turn our metamorphic rock into igneous rock, we're going to melt it in boiling water. When our rock has cooled, you can see the pieces combined to make an igneous rock with uniform structure.

(Describer) It’s black.

Pretty cool, huh?

(male narrator) This is part of the story. We showed one path through the rock cycle, but any rock can go from one type to another. For example, igneous rocks can turn into either metamorphic or sedimentary. And metamorphic rocks don't have to become igneous rocks. They can be broken down again and become sedimentary. Or sedimentary rocks can get pushed within the Earth to form igneous. See? All of the rock types are connected, making a cycle that never ends.

[rock music]

(Describer) The woman dressed as sedimentary rock sings while the men dressed as metamorphic and igneous rocks pretend to play guitar and drums. Titles: Made by Allie Anderson, Rita Domingues, Brad Holschuh, Aaron Johnson, Justin Kaderka. Music by Zep Herme, Luffy (under Creative Commons). Except where otherwise noted, this work is licensed under Creative Commons: Attribution, Non-Commercial, Share-Alike. Accessibility provided by the U.S. Department of Education.

♪ We are the rocks of the world ♪

♪ Whoa-ho-ho Rocking ♪

♪ We are rocking so much ♪

♪ Until tonight ♪

♪ Rockin', baby ♪

♪ Whoo-hoo Rockin' to the beat ♪

♪ Rockin', baby ♪

♪ Whoo-hoo, whoo-hoo ♪

♪ Rocking until the sun comes up ♪♪

Accessibility provided by the U.S. Department of Education.

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Learn the differences between sedimentary, metamorphic, and igneous rocks.

Media Details

Runtime: 5 minutes

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