The ocean floor is that area of the Earth's crust covered by ocean water. It is divided into the continental margins and the deep-sea basins.

Continental Margins

The continental margin is the part of the seafloor at the edges of the continents and major islands where, just beyond the shoreline, it tapers gently into the deep sea. The continental margin includes the continental shelf, the continental slope, and the continental rise.

Continental shelf The continental shelf is that part of the margin that begins at the shoreline. It is flat and its width varies. At Cape Canaveral, Florida, for example, there is no shelf. Off the coast of Texas, however, the shelf is 125 miles (200 kilometers) wide. The continental shelf is usually less than 660 feet (200 meters) below sea level. It receives much rich sediment (soil and other particles) from rivers that...