2. Explored through mines and wells Temperature and pressure increases with depth Earthquake (Seismic) Waves scientists are able to tell the density and composition of materials in the Earth by how these waves travel through the Earth

3. Differences in density resulted in materials within Earth forming layers Crust – least dense Mantle Core – most dense

4. the brittle, rocky outer layer of Earth very thin compared to other layers, like the shell of an egg composed of magnesium and iron earthquake waves speed up through this layer because it is the least dense Two types: Oceanic Crust – crust under the oceans Continental Crust – crust on land (thicker)

5. thick middle layer in the solid part of the Earth contains more iron and magnesium than the crust, making it more dense

6. Uppermost Mantle (Lithosphere) similar rocks to that of the crust Asthenosphere heated rocks begin to melt and flow slowly underneath the lithosphere Upper Mantle higher temperatures and high pressure cause rocks to stop melting and become solid again Lower Mantle most dense part of the mantle

7. dense and metallic center of the Earth composed mainly of iron and a small amount of nickel

8. Outer Core higher temperatures outweigh the high pressure and makes the outer core a liquid discovered by analyzing earthquake wave data high pressure outweighs the high temperatures and makes the inner core a ball of dense, solid iron spins faster than the rest of Earth Inner Core

9. The spinning of Earth’s inner core causes the molten iron of the outer core to move around forming a magnetic field around the Earth Magnetosphere – outer part of the magnetic field that protects Earth and interacts with charged particles from the sun