The seafloor buckles where drifting plates that make up the Earth's outer shell slowly, over millions of years, collide.
(The seafloor; buckles; where drifting plates that make up the Earth's outer shell slowly, over millions of years, collide) (plates; make up slowly; the Earth's outer shell)
The seafloor plates
buckles make up slowly
where drifting plates that make up the Earth's outer shell slowly, over millions of years, collide
the Earth's outer shell