They collect direct evidence from rock samples and indirect evidence from seismic waves
Answer: The correct answer is : Geologists have used two types of evidence, a direct one that are samples of rocks and an indirect one that is of seismic waves.
Explanation: Extreme conditions inside the earth have always prevented a very internal exploration. Direct evidence is obtained when forces inside the earth throw rocks at the surface from depths of more than 100km.
From the indirect evidence that seismic waves are, geologists have learned that the earth has several layers inside. Geologists observe the records of seismic waves and study how they travel through the earth, their speed and the route they take to determine the structure of the planet.
