How and why earth material seperated into layers.

After several million years, the Earth separated into several layers. Iron, nickel and other heavy metals mostly settled to the core; lighter elements remained in the mantle around the core. The lightest elements, such as oxygen and silicon, floated to the top and cooled, forming a solid crust. Because the Earth was not completely liquid, the layering process was uneven; pockets of heavy elements remained in the crust.

[content deleted] - user123802726recklesschicken

it creates acid rain