• 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)
• Thin, rocky, outer layer of Earth.
– Two types:
• Continental crust (continents or land)
• Oceanic crust (under the ocean)
• The crust and the solid uppermost layer of
• Heated rock under the crust.
– Rock is heated so much it acts like
• The thick middle layer of Earth
– Composed of rock
8. The Outer Core
• A layer of melted metal (iron and nickel)
• Denser than the mantle
9. The Outer Core
• Solid ball of iron.
• Earth’s densest layer.
• Temperature comparable to the surface of