Although lithogenous sediments are dominant in many areas, biogenous and hydrogenous sediments are also abundant because the accumulation rate of all sediments is very slow. Abyssal clay cover most of the deep ocean floor. Oozes are found at slightly shallower depths. They are tiny shells of plants and animals and are important sources of sediment. Production of the plankton which make most of this material is greatest in coastal upwelling regions and at equatorial divergences.
Destruction occurs mainly through dissolution.
The ocean is undersaturated with silica at all depths. It varies from 3500 to 6000 m depth. Manganese nodules are poorly understood. They occur in deep ocean environments where other sediments accumulate slowly. Most with economic potential are from areas with moderate surface productivity and are rich in copper and nickel.