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 the Earth of waves generated by large 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 large earthquakes to image the interior of Earth. These waves travel through the different layers of Earth and their speed and path help scientists determine the thickness, density, and composition of each layer.

A Cross Section of Earth Reveals a Layered Structure That