Differentiation of the Earth

As we covered previously, the Earth was likely formed from the collision of dust and rocks circling the sun.  The kinetic energy of these collisions was converted to heat.  Because of the heat and constant bombardment the very early Earth would have been a largely molten homogeneous mass (1).

As the bombardment slowed and essentially ceased, the materials that made up the Earth would begin to sink or float depending on their density.  Lighter less dense materials float, while the heavier denser materials sink.  As the surface of the Earth cooled, a solid crust formed with lighter water covering most of it and even lighter gases surrounding everything.

This process is differentiation.