I think Geologists have used two main types of evidence to learnabout Earth's interior: direct evidence from rock samples and indirect evidence from seismic waves. The geologists in Figure 2 are observing rock on Earth's surface.
Geologist use rock samples to learn more about conditions deep inside of the Earth. Using rock core samples and rocks ejected from deep underground, geologists are able to infer information about the conditions under which the rocks were formed.
