The Rock Cycle

I'm Tessa. Welcome to Fun Science Demos. Today, the big idea is rocks and how they're formed. We know that all rocks are made from minerals. Today, I'm going to show you a cool demonstration about how rocks are formed. Rocks are made from minerals. We have to start our demonstration with my minerals. Let's take a closer look at this first type of rock. When I look at it, I see layers going through it. So, let's try to make a rock with layers. I have here little bits of crayon that represent minerals and rocks, sediment. These layers are going to pile up at the bottom of oceans and at the bottom of lakes. They're going to pile up on top of each other. They're going to get mixed up. They're just going to keep piling, kind of like a layer cake. I'm making myself a little layer cake here. As they pile, slowly, they become this type of rock. When you look closely, I see my layers. I see my minerals. I see my sediment. I see them all on top of each other at the bottom of the ocean. This first type of rock is formed from layers of sediment. It's called a sedimentary rock. Sediment. Sedimentary. Perfect. Rock type number two. Here's an example of rock type number two. If I look closely at it, I still see some layers. But it's no longer a sedimentary rock because more change has happened to it. When I look at my model of a sedimentary rock and I start changing my sedimentary rock, I'm only going to apply some pressure. I'm going to use my hand to apply that pressure. I'm going to press. My hands, naturally, have a little bit of heat. Not only am I applying pressure, but I'm applying heat. This heat and this pressure is causing my sedimentary rock to change. This new type of rock is called a metamorphic rock. Metamorphic means changed. I've applied heat and pressure to my rock. Now I have a metamorphic rock. The next type of rock is formed from liquid rock. But how do I get liquid rock? Well, I can change a solid to a liquid with heat. This happens deep inside the earth. I'm going to use this hot plate to show you. If I put my metamorphic rock and apply heat, it's going to begin to melt. It's going to begin to melt very quickly. For my model, in real life, this takes a long time. This change happens deep inside the earth. As this liquid rock, we've given it a special name. It's called magma. You watching the change in the color? The change in the texture? The entire thing has almost changed. The colors are really mixing. I now have magma. I've given my liquid rock, also called magma, some time to cool. I look at it. It's going to be a little bit different than a liquid. It's now a solid. It's a rock. This type of rock is called an igneous rock. Here's an igneous rock. Pretty cool. Let's review. Layers of sediment built up under the ocean? Sedimentary rock. Rock changed from heat and pressure? Metamorphic rock. Liquid rock cooled? Igneous rock. Rocks are formed through this process called the rock cycle. If you'd like to learn more about the rock cycle, check out the links in the video description. Science is so cool!