the mantle and core are composed of different material
P waves refract as they travel through Earth. The shadow zone exists because of seismic waves. The shadows show when the earth spins around.
The weight of the rocks in the crust and upper mantle results in the pressure that allows diamonds to form.
Wondering slowly with no pattern
The oldest continental crust would be between three and one half to four billion years older than the oldest oceanic crust. This is due to the fact that ocean plates are subducted under the continental plates, subjected to partial melt and essentially recycled in the mantle before reforming.
The iron nickel core has been determined to actually exist from the examination of meteorites, from the gravitational field of Earth, and from the Earth's density in comparison to its volume.
It is called folding when rocks bend without breaking because of plate movement.
The molten bit of the Iron core.
Liquid.APEX