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The Ocean Basins Three Major Oceans Pacific Atlantic Indian Three Major Oceans Atlantic – the shallowest ocean (3.3km average depth) Indian – second shallowest ocean (3.8km average depth) Pacific – the deepest ocean (3.9km average depth) What is a sea? Small area of the ocean that is partially surrounded by land The Seven Seas Numerous seas – they are all considered part of an ocean Exploring our Oceans • Oceanography is the study of the physical characteristics, chemical composition and life forms of the ocean. What are Submersibles? • Underwater research vessels The Alvin The Jason SONAR • Important to help map ocean floor • Sound Navigation and Ranging How SONAR works… receiver ocean surface transmitter ocean floor Differences in the time it takes for the sound waves to leave the boat and then return tell scientists how deep the ocean bottom is. Features of the Ocean Basins • Continental margin: portion of ocean made up of continental crust Features of the Ocean Basins • continental shelf: flat part of continental margin covered by shallow ocean water Formed by changes in sea level Avg depth = 60 m Features of the Ocean Basins • continental slope: boundary between continental crust and oceanic Features of the Ocean Basins • submarine canyons: deep, v-shaped valley that cuts through shelf & slope Features of the Ocean Basins • continental rise: wedge of sediments that separates slope from ocean floor Features of the Ocean Basins • abyssal plain: large flat area on the ocean floor Features of the Ocean Basins • seamount: underwater volcanic mountain (1000m) Features of the Ocean Basins • guyot: a flat-topped submerged seamount Features of the Ocean Basins • trench: deep narrow valleys along the edges of ocean floor Marianas Trench in Pacific ocean is 36,000 ft deep (6mi) – deepest point Features of the Ocean Basins • mid-ocean ridge: mountain range on ocean floor Features of the Ocean Basins • rift valley: deep crevice in between mountain ranges Features of the Ocean Basins • coral reef: limestone structures containing shells of animals that surround volcanic islands
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