Volcanoes are one of Earth’s most magnificent land features.
In this lesson, you’ll learn about volcanoes, how they’re formed, what’s inside them, and why some volcanoes look different than others.
What Is a Volcano?
What do you say to an upset volcano? You seem a little hot-headed right now! Heat does play a large part in the creation of volcanoes. The process starts deep within the earth, which is made of several layers, including the core in the middle, the mantle above the core, and the crust at the surface of the earth.The top part of the mantle is made of very hot melted rock called magma. Above that is Earth’s crust, which is broken in huge pieces of rock called plates.
These plates float very slowly on the mantle – we’re talking just a couple of centimeters a year. A volcano is a type of mountain that is created when some of that magma travels up through the plates to the earth’s surface.
How Are Volcanoes Formed?
The earth’s plates move in different ways, and sometimes these movements can help to create volcanoes. Sometimes, the plates collide into each other.
This is called a destructive plate boundary. Other times, an oceanic plate collides with a continental plate, causing the oceanic plate to slide under the other. When this happens, some of the magma rises to the top. And when it happens over and over in the same spot, a volcano is created and grows with every eruption.Earth’s plates can also move away from each other to create a volcano. This is called a constructive plate boundary. As the plates move apart, magma rises up through the newly created gap.
The magma eventually cools off, creating new crust. Just like with destructive plate boundaries, volcanoes are created this way when the process happens repeatedly in the same location.
What’s in a Volcano?
When you look at a volcano, you can only see part of it. However, it’s made of several main parts, inside and out. The magma that moves up from the earth’s mantle collects and is stored in an area under the crust called a chamber. When the plates move either together or apart, that magma travels up tunnels called vents, which open up at the top in an area known as a crater. When the magma leaves the volcano, it’s then called lava.
Besides lava, sometimes ash, gas, and steam also leave the volcano.
Why Do Volcanoes Look Different?
Although most volcanoes are formed in the same basic way, some things happen differently as they form. This is what helps scientists classify volcanoes into three groups: composite volcanoes, cinder cone volcanoes, and shield volcanoes.
Composite volcanoes are the ones we see mostly on television. They are made up of layers of lava mixed with volcanic ash. Cinder cone volcanoes are made mostly of cinders that are released from the volcano. Shield volcanoes are mostly made of hardened lava and have much lower slopes than composite and cinder cone volcanoes.
Volcanoes are formed when the earth’s plates move together or apart, causing magma to come up to the earth’s surface. When magma reaches the surface, it’s called lava. Different mixtures of lava help to create different types of volcanoes, including composite volcanoes, cinder cone volcanoes, and shield volcanoes.