The field of oceanography is usually broken down into sub-disciplines, including: [Biological Oceanography] -- the study of marine organisms (plants and animals) and the relationship between those organisms and the environment of the oceans [Chemical Oceanography] -- the study of the composition of seawater , its processes and cycles - current and historical, and the chemical exchanges between atmosphere and ocean [Geological Oceanography] -- the study of the earth at the land/sea margin and below its surface, and the history of the processes that formed the ocean basins, continents and islands such as plate tectonics, volcanoes and earthquakes [Physical Oceanography] -- the study of how and why oceans move, including examinations of waves, currents, eddies, gyres and tides, and the interactions of atmospheric and oceanic movements [Ocean Engineering] -- the discipline involved with the design and construction of scientific equipment and installations for use at sea; also studied are the interaction of the sea with the works of humankind [Marine Policy and Law] -- covers a broad range of ocean resource management issues, including the laws, regulations and policies concerning ocean environmental quality, fisheries, coastal zone management, marine archaeology and aquaculture.