The ocean floor spreading and the subsidence of cooling oceanic plate, the transport and settling down of terrigenous sediments, the transport along the continental slope, consolidation and isostatic subsidence of sedimentary layers are considered
of the ocean bottom relief. There are three types of motions, namely vertical (subsidence) at mid-oceanic ridges, horizontal (moving apart) at continental terraces and diagonal motions (down and apart from the ridge axis) within abyssal plains. Progressive