Arrange the events to describe how a volcano forms and erupts. the plates move constantly. molten magma flowing beneath earth's surface finds its way out of the gaps. the mound cools down over thousands of years to form a mountain. the heap grows bigger and bigger as the volcano erupts, creating a huge mound. at times, the plates move away from each other, creating gaps. earth's crust is made up of huge slabs called plates. magma comes out of earth, creating a heap of lava, ash, and rocks.