1. What is Inside the Earth?

2. Layers of the Earth
The Earth is divided into two different sets of layers, by two different methods: chemical composition and physical properties.

3. Layers by Chemical Composition – 3-Layer Way C is the third letter
The three layers divided by chemical composition are the Crust, the Mantle, and the Core.
These layers are divided based on the density of the ingredients that make up each layer.
The densest ingredients are pulled to the center due to gravity.

4. The Crust
The crust is the outermost layer of the Earth, and is also the thinnest.
The crust is km thick or about 1% of the Earth’s mass.
Both types are made mainly of oxygen, silicon, and aluminum. There are two types of tectonic plates: oceanic and continental.
Continental crust is thick and fluffy while oceanic crust thin and dense
Oceanic crust is more dense than continental crust.

5. The Mantle
The mantle is located between the core and the crust and is about 66% of the Earth’s mass.
It is a region of hot, slow-flowing rock.
The mantle is denser than the crust.
It contains magnesium and iron.

6. The Core
The core extends from below the mantle to the center of Earth.
Scientists think that the core is made mostly of iron and nickel.
The core is the densest layer, and makes up about 33% (one third 1/3) of the Earth’s mass.

7. How is the 3-layer way like an egg?

8. Layers by Physical Properties – 5-Layer Way 5= F (sound)
The Earth can also be divided into layers based on physical properties (texture).
These physical properties include whether the layer is solid or liquid, and how well the layer transfers energy waves.
The five physical layers are the Lithosphere, Asthenosphere, Mesosphere, Outer Core, and Inner Core.

9. Lithosphere
The lithosphere is the outermost, rigid layer of Earth (brittle plates).
The lithosphere is divided into pieces called tectonic plates.

10. Asthenosphere
The asthenosphere is a layer of plastic, or soft rock that flows slowly (hot playdoh).
The tectonic plates move on top of this layer because of convection currents in this layer.
Convection currents are the circular movement of rock material where warmer material rises, and the cooler material sinks.

11. Mesosphere The mesosphere is the strong, lower part of the mantle.
The mesosphere extends from the bottom of the asthenosphere to the Earth’s outer core.
Made of solid rock.

12. Outer Core The outer core is the liquid metal layer of Earth’s core.
It lays beneath the mesosphere and surrounds the inner core.
The rotation of this liquid metal creates a magnetic field in Earth and gives us a north pole and a south pole.

13. Inner Core The inner core is the solid, most dense center of Earth.
The inner core extends from the bottom of the outer core to the center of Earth.

14. How do we know what’s inside Earth?
Scientists measure the path of seismic waves from earthquakes to predict the type of material at different depths inside the earth.
The seismic waves move differently through solid, softer, and liquid rock material.