The Ocean Floor Chapter 14

What is Oceanography?  Oceanography  science that draws on the methods and knowledge of geology, chemistry, physics, and biology to study all aspects of the world ocean

Water on the Earth  61% found in the Northern Hemisphere  81% found in the Southern Hemisphere  71% total on Earth

The Four Oceans  Pacific –largest and the greatest average depth  Atlantic –shallowest  Indian  Arctic

Mapping the Ocean Floor  Bathymetry  measurement of ocean depths and the charting of the shape or topography of the ocean floor

Mapping the Ocean Floor  Sonar is an acronym for sound navigation and ranging. It is also referred to as echo sounding  transmitting sound waves toward the ocean bottom

Mapping the Ocean Floor  Satellites  able to measure small differences by bouncing microwaves off the ocean surface

Mapping the Ocean Floor  Submersibles are small underwater crafts used for deep-sea research  remotely operated vehicles (ROVs)

Main Ocean Floor Regions  Continental Margin  Ocean Basin Floor  Mid-Ocean Ridge

Continental Margin  Continental shelf is the gently sloping submerged surface extending from the shoreline  mineral deposits, large reservoirs of oil and natural gas, and huge sand and gravel deposits  Continental slope is the steep gradient that leads to the deep-ocean floor  Continental rise is the gently sloping surface at the base of the continental slope.

Ocean Basin Floor  Trenches form at the sites of plate convergence where one moving plate descends beneath another  Abyssal plain is a very level area of the deep-ocean floor  Seamount is an underwater volcano at least 1000 meters above the deep-ocean floor  Guyot is an eroded, submerged seamount.

Mid-Ocean Ridges  Seafloor spreading  process by which plate tectonics produces new oceanic lithosphere at ocean ridges  New ocean floor is formed  Hydrothermal Vents  mineral-rich water is heated by the hot, newly-formed oceanic crust and escapes through cracks in the oceanic crust into surrounding ocean water

Types of Seafloor Sediments  Terrigenous sediments: mineral grains that were eroded  Biogenous sediments: shells and skeletons of marine animals and algae  Hydrogenous sediment: minerals that crystallize directly from ocean water through various chemical reactions

Resources From the Sea  Oil and natural gas  main energy products currently being obtained from the ocean floor  Gas hydrates  compact chemical structures made of water and natural gas

Resources From the Sea  Sand and Gravel  Used to fill in recreational beaches and make concrete  Manganese nodules  Extracted to make permanent magnets and engine parts  Evaporative Salts  halite—table salt  Used for preserving foods and de-icing roads

Which Ocean Has the Greatest Salt Quantity?  Dead Sea  38% salt content