The Earth's interior is measured by density. The less dense layers are nearer to the top and the more dense lie deep within
the core. There is evidence that shows the accuracy of this statement. Scientist claim that the rocks are more dense when
they lie deep within the mantle than when they are at the surface. This is due to pressure put on them. To find the density
you need use Newton's Law of Gravitation.
More evidence comes from the speed of earthquake waves. These waves move faster deeper in the earth which proves that it is
more dense deeper in the earth. By obtaining this information scientists are able to determine things about the temperature,
pressure, and rock type that are in the earth.