Here's how it works:

1. Magma Formation: Magma originates deep within the Earth, often with a mafic composition (rich in magnesium and iron).

2. Cooling and Crystallization: As the magma rises towards the surface, it starts to cool. As it cools, minerals with higher melting points (like olivine and pyroxene, which are mafic) start to crystallize first.

3. Gravity Settling: These denser crystals sink to the bottom of the magma chamber, accumulating and forming a layer of mafic minerals.

4. Remaining Magma: The remaining magma becomes enriched in lighter elements like silica and sodium, making it more felsic.

5. Further Crystallization: As the magma continues to cool, the felsic minerals crystallize and accumulate at the top of the magma chamber.

6. Pluton Formation: Eventually, the magma cools completely, forming a pluton. The bottom of the pluton will be composed of the early-formed mafic minerals, while the top will be composed of the later-formed felsic minerals.

In summary: Crystallization differentiation is a process where different minerals crystallize at different temperatures and densities within a cooling magma chamber, leading to a layering effect with mafic minerals at the bottom and felsic minerals at the top.