PLATE TECTONICS
This illustration reveals how the lithosphere is composed of both the crust and the upper part of the mantle which is solid.  Together, they carry all of the Earth's oceans, and land masses.  The astheno-
sphere is the fluid part of the mantle and its continual motion is the driving force behind the movement of the lithosphere.

EARTH'S MAGNETIC FIELD
The outer part of the core is liquid and it is in constant motion in response to the rotation of the Earth on its axis.  This constant motion is responsible for the magnetic lines of force that emanate from the Earth.