Oceanic plate is subducted back into the asthenosphere at trenches Frictional heating along the plate boundary gives rise to arc volcanism
passive margin between the ocean crust and continental margin
Genesis of the lithosphere at a mid-ocean ridge Spreading causes the ocean basin to grow
Fig.19-3, pg 461: Press, F. and Siever, R. (1978) Earth (second edition). W.H. Freeman, SanFrisco.