2. Layers
• Earth’s interior is made up of layers.
• Each layer has a different composition,
pressure, and temperature.
3. Seismic Waves
• Scientist learned about the Earth’s layers
using seismic waves from earthquakes.
• Wave’s speed and direction change when
going through different materials (solid
rock, liquid rock, solid metal, liquid metal)
4. Crust
• Thin, rocky, outer layer of Earth.
– Two types:
• Continental crust (continents or land)
• Oceanic crust (under the ocean)