What Is a Volcano Made Of?

🕐 5 min 26 sec 👦 Ages 9–12 🌍 English
Join Koko and Owlo as they explore the fascinating world of volcanoes and discover what they're made of!
Understand the structure of a volcano Learn about lava and its temperature Explore the layers of the Earth
📖 Story Script
                    Koko:
                    Owlo, I have to tell you something incredible. My class went on a field trip to the natural history museum yesterday.
                
                    Owlo:
                    Oh, that sounds wonderful, Koko! What was your favourite part of the whole museum?
                
                    Koko:
                    There was this giant model of a volcano, and it was actually erupting with fake lava. It was so cool. I could not stop staring at it.
                
                    Owlo:
                    I can picture it perfectly. Volcanoes have that effect on people. They are one of the most dramatic things on our entire planet.
                
                    Koko:
                    The guide said the lava was over a thousand degrees. I could not even imagine how hot that is. What is a volcano actually made of?
                
                    Owlo:
                    That is exactly the right question to ask. Let me grab something from the shelf first.
                
                    Koko:
                    Is that a book about volcanoes? The cover has a huge eruption on it. I want to see inside.
                
                    Owlo:
                    This is one of my favourites in the whole library. It has incredible diagrams of what is happening deep underground. Let us open it to the cross-section page.
                
                    Koko:
                    Whoa, it looks like a layered cake. There are all these different sections going down into the Earth.
                
                    Owlo:
                    That is actually a perfect way to describe it, Koko. The Earth has layers, just like that. The very centre is called the core, and it is incredibly hot.
                
                    Koko:
                    Hotter than the fake lava at the museum?
                
                    Owlo:
                    Much, much hotter. The core can reach temperatures of around five thousand degrees. As we move outward from the core, we reach a layer called the mantle.
                
                    Koko:
                    What is the mantle made of?
                
                    Owlo:
                    The mantle is made of rock, but here is the surprising part. Deep inside, that rock gets so hot that it becomes soft and almost like a very thick, slow liquid.
                
                    Koko:
                    So the ground under us is actually kind of melted? That is a strange thought.
                
                    Owlo:
                    It is strange, but true. That melted rock inside the Earth has a special name. It is called magma.
                
                    Koko:
                    Magma. I have heard that word before. Is that the same as lava?
                
                    Owlo:
                    Almost, but not quite. Magma is the name for melted rock while it is still underground. The moment it breaks through the surface, we call it lava.
                
                    Koko:
                    So it is the same stuff, just with a different name depending on where it is. That is actually kind of clever.
                
                    Owlo:
                    I never thought of it that way, but yes, that is exactly right. Now, how do you think that magma gets from deep underground all the way up to the surface?
                
                    Koko:
                    Maybe it pushes its way up? Like when you squeeze a tube of toothpaste too hard?
                
                    Owlo:
                    That is a brilliant comparison. Magma is lighter than the solid rock around it, so it slowly pushes upward through cracks and weak spots in the Earth's crust.
                
                    Koko:
                    And the volcano is like the opening where it finally bursts out?
                
                    Owlo:
                    Exactly. A volcano is essentially an opening, or a vent, in the Earth's surface. Beneath it is a chamber, like a underground room, where magma collects and builds up pressure.
                
                    Koko:
                    So the mountain part of a volcano, is that built from old lava?
                
                    Owlo:
                    Precisely. Every time a volcano erupts, lava flows out and cools down. It hardens into solid rock. Over thousands of years, layer after layer builds up and forms that cone shape.
                
                    Koko:
                    So the whole mountain is basically made of cooled lava from old eruptions. The volcano built itself.
                
                    Owlo:
                    That is a wonderful way to put it. Along with lava, volcanoes also shoot out ash, gases, and chunks of rock called volcanic rock or pumice.
                
                    Koko:
                    I have seen pumice before. My mum has a piece of it. It is so light and full of tiny holes.
                
                    Owlo:
                    That is because pumice forms when lava cools so quickly that gas bubbles get trapped inside. Those bubbles leave all those tiny holes behind.
                
                    Koko:
                    That is amazing. So even that little rock in the bathroom came from a volcano somewhere.
                
                    Owlo:
                    It very likely did. Volcanic rock is found all over the world. In fact, some of the most fertile farmland on Earth sits near old volcanoes, because volcanic ash makes soil incredibly rich.
                
                    Koko:
                    So volcanoes are scary, but also kind of helpful for the planet?
                
                    Owlo:
                    Exactly right. They are part of how our planet renews itself. They have been shaping the Earth's surface for billions of years.
                
                    Koko:
                    Okay, so here is what I learned today. The Earth has super hot melted rock inside it called magma. When that magma pushes up through a crack in the surface, it becomes lava. A volcano is basically the Earth's way of letting all that pressure out. And over time, all that cooled lava stacks up and builds a mountain. Oh, and pumice, that floaty holey rock, is basically lava with trapped bubbles. Next I want to find out why some volcanoes explode violently and others just kind of ooze slowly. Because that seems like a very important difference.
                
                    Owlo:
                    That is a perfect summary, Koko, and an excellent question for next time. You are thinking like a real geologist.