P waves are shown as straight arrows and the S waves are arrows with a wave. The mantle, outer core and inner core are shown as well. The diagram shows that as P waves move toward the earth’s outer core they are reflected, refracted or deflected. S waves are blocked and do not enter the outer core. This suggest to geologist that the earth’s outer core must be made of liquid because S waves cannot pass through liquids. The shadow zone is also shown in the cross section.