The main mechanism through which the layering happened is gravity: it pulled the heavier, denser material to the center, leaving the less dense material on the surface.
The material that was on the outside cooled quicker, but this was the result, not the cause.
The answer is
<span>2) Gravity caused more-dense material to move toward the center of each planet.</span>
Volcanic eruptions are formed when so much PRESSURE from the magma inside the volcano builds up to it's boiling point.
An example would be like shaking soda as soon as the pressure is released there is foam. It's then same concept but with magma aka lava
Hope this helped
We don't know sorry hahahaha
