4. -Rocks from inside Earth give geologists clues about earths structure. -This is direct evidence. Something you can physically observe. Geologists have only drilled 3.8 kilometers into the Earth’s crust. To reach the Earth’s center they would have to dig 6,000 kilometers which is 1600 times the deepest mine.

5. -Geologist observe seismic waves and study how they travel through the Earth. -Different types of seismic waves travel differently. The speed of the waves and the paths they take reveal the structure of the planet. -Using data from seismic waves, geologists have learned that earth’s interior is made up of layers. Like an Onion.

9. -Digging from the surface the rock starts off cool. -~ about 20 meters down starts to get warmer. For every 40 meters you descend the temperature increases 1 Celsius degree. -This rise in temperature continues for several tens of km. -After that it continues more slowly, but steadily