A cross section of Earth reveals a layered structure that has different thicknesses and densities. How do geologists know this?
A) from drilling and digging down into the various layers
B) from observing the characteristics of lava and gas issuing from volcanic vents
C) from observing the transit times through Earth of seismic waves generated by earthquakes
D) from comparisons with drill cores taken by robot spacecraft on Mars and Venus

Question

Quizplus · Accepted Answer

Geologists use seismic waves generated by earthquakes to study Earth's interior. The waves travel at different speeds through different materials, allowing scientists to infer the structure and composition of Earth's layers.

A Cross Section of Earth Reveals a Layered Structure That