Answer:
When the magma, a molten rock flows as lava at the planet's surface, the surface gets cooled after a long, this whole process cause formation of some kinds of minerals on that surface.
Explanation:
Magma and Lava both are types of molten rock. The underground molten rock is called magma while the exploded molten rock on surface is known as lava. When these rocks cools down they get solidified and form crystal rock structure. Cooled magma is called plutonic igneous rock and cooled lava is called volcanic igneous rock. These rock crystals are of different sizes and consist several minerals such as Silicon(Si), Sodium (Na), Potassium (K), Aluminium (Al), Iron(Fe), Magnesium(Mg), Calcium(Ca). Some rocks that forms minerals consist high amount of iron. The amount of minerals and elements in every rock can very depending on shape and size.
Seems very basic, the ocean is above the plate, the plate material is heavier than water (it being rock). That's pretty much all of it. The plates grind a little and new land pushes up at plate boundaries but this does not seem to be related. The heavier material is below and the lighter above, those being rock and water respectively.
