['Magma comes out of the rift valley.', 'Magma cools to rock and hardens.', 'Rock is pushed away as new rock is formed at MOR.', 'Oceanic crust and continental crust meet at the trench.', 'Oceanic crust bends down under the continental crust.', 'Gravity pulls rock towards mantle.', 'Rock melts to mantle.']