Even though we can’t see very far into the earth, geologists have a lot of cool ways to make pictures of its layers. Like a child’s jawbreaker, Earth is made up of layers that are made of different things and get hotter and more pressurized as you get closer to the centre of the planet.
The earth is made up of:
- The crust is 5 to 70 km thick.
- This layer is 2,900 kilometres thick.
- The outer core is 2,200 kilometres thick.
- Inner Core: between 1,230 and 1,530 km thick.
Earth’s Layers
1. Crust
We walk every day on the crust of the earth. It is the thin (relatively) outermost layer that wraps around the Earth and has temperatures between 500°C and 1,000°C. There are two kinds of crust: continental and oceanic. The crust of the earth is 5–70 km thick.
The land on Earth is made up of the continental crust, which is 35–70 km thick, less dense, and mostly made of rock granite.
Most of the ocean is made up of oceanic crust, which is denser, thinner (5–7 km), and mostly made of the rock basalt.
Only 1% of the volume of Earth is made up of the crust.
2. Cover
The mantle is just below the crust. The mantle is mostly liquid and can be shaped like plastic. It makes up 84% of the volume of the Earth. The mantle of the earth is 2,900 km thick and is divided into three main zones: the lithosphere, the asthenosphere, and the mesosphere.
The lithosphere is a little confusing because it includes both the bottom of the crust and the top of the mantle. It has a thickness of about 100 km and is made up of the 15 largest tectonic plates on Earth.
The mantle becomes much more fluid and flows in the asthenosphere. This makes it possible for the tectonic plates above it to move around the Earth.
In the mesosphere, which is the deepest part of the mantle, temperatures and pressures are so high that the rock gets harder and doesn’t move as easily.
Fun fact: Olivine, which is also called peridot when it is of gem quality, is the most common mineral in the mantle.
3. Outside Center
The mantle is on top of the outer core. This layer of liquid iron and nickel spins as the planet turns, creating the magnetic field of the Earth. This magnetic field helps keep us safe from the radiation from the sun. At up to 6,100 °C, the outer core is 2,200 km thick and very hot.
Fun Fact: Without the magnetic field of the outer core, our planet would be like Mars, which is mostly empty.
4. Inner Core
The deepest part of the earth is its inner core. It is also made of iron and nickel, but because of the high pressure, it is no longer a liquid. The inner core is about 5505 °C, which is as hot as the surface of the sun. The inner core of the earth is between 1,230 and 1,530 kilometres thick.
Fun fact: The inner core of the earth grows by 1mm each year. At some point, the entire outer core will solidify and become part of the inner core. Don’t worry, though, because that won’t happen for a very long time.
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