1. What is the earth like inside?
Earth’s Interior Notes
What is the earth like inside?

2. The earth is made up of layers that formed from differences in density
The earth is made up of layers that formed from differences in density. Let’s look at them…

3. Inner Core Outer Core The Core Discovered 1906 Solid iron & nickel.
1,200 km thick
Density – 15 g/cm3
Discovered 1936
Outer Core
Liquid iron & nickel.
2200C C.
2,250 km thick;
Density – 10 g/cm3
Discovered 1926

4. Mantle (Lower & Upper) Made of Si, O, Fe, & Mg. 870C to 2200C.
2,900 km thick
Density – 5 g/cm3

5. Upper Mantle - Asthenosphere
Partly melted & plastic.
150 km thick
Density – 3.5 g/cm3
Plasticity – the ability for
a solid to flow like a
liquid. Think of asphalt.

6. Moho The boundary between the mantle & the crust.
Lithosphere
The outer, hard part of the Earth

8. Continental Crust Oceanic Crust 30-50 km thick Granite
High in Al, Mg, K, & Si
Density – 2.7 g/cm3
Oceanic Crust
5 - 7 km thick
Basaltic rock
High in Fe, Mg, & Ca
Density – 3 g/cm3

9. Discovering Earth’s Interior

10. How do we know what’s inside the earth?
We use seismic waves to take an x-ray of it!
Earthquakes Produce different types of seismic waves that can be detected far from the epicenter (origin).

11. Different Types of Seismic Waves…
P-waves Fast, compressional waves that travel through solids & fluids. The denser the substance, the faster they travel.
S-waves Slower, shear waves that travel through solids only.
Lookie Here!

12. Shadow Zone An area where no seismic waves occur.
S-wave No S-waves pass between 105˚ to 180˚ Shadow b/c they cannot go through a liquid Zone (outer core).

13. P-wave. No P-waves pass between 105˚ to Shadow. 140˚
P-wave No P-waves pass between 105˚ to Shadow 140˚. They are bent around this Zones area b/c of a change in velocity.
See it in action!