The Mid-Atlantic Ridge dissects the entire length of the Atlantic in a series of rifts and fractures. In the central Atlantic, with relatively narrow continental shelves, it is easy to see where the coasts on either side of the ocean were once joined. The ridge mostly lies 4,900–9,800 ft (1,500–3,000 m) below sea level, although the volcanoes of Ascension Island and Saint Helena breach the surface. The sea floor gets deeper and older away from the center, and smoother as its features are covered in sediments. The featureless abyssal plains of the Angola and Brazil basins lie to the east and west, respectively. The ridge is displaced east–west at numerous points by transform faults, where the African and South American plates are moving past each other. These fracture zones extend some distance from the ridge, sometimes as active faults where parts of the same plate are moving at different speeds.