1. The Ocean Floor Chapter 14

2. 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

3. Water on the Earth • 61% found in the Northern Hemisphere • 81% found in the Southern Hemisphere • 71% total on Earth

4. The Four Oceans • Pacific –largest and the greatest average depth • Atlantic –shallowest • Indian • Arctic

5. Mapping the Ocean Floor • Bathymetry • measurement of ocean depths and the charting of the shape or topography of the ocean floor

6. 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

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

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

9. Main Ocean Floor Regions • Continental Margin • Ocean Basin Floor • Mid-Ocean Ridge

10. 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.

11. 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 • Guyotis an eroded, submerged seamount.

12. 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

13. 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

14. 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

15. 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

16. Which Ocean Has the Greatest Salt Quantity? • Dead Sea • 38% salt content