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EARTH: The Water Planet

EARTH: The Water Planet. The Ocean. Covers 71% of Earth Make up 80% of Southern Hemisphere Only 61% of Northern Hemisphere Regulates atmosphere and weather Really only 1 interconnected ocean Few natural partitions Traditionally classified into 4 basins. Pacific Ocean. Deepest and largest

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EARTH: The Water Planet

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  1. EARTH:The Water Planet

  2. The Ocean • Covers 71% of Earth • Make up 80% of Southern Hemisphere • Only 61% of Northern Hemisphere • Regulates atmosphere and weather • Really only 1 interconnected ocean • Few natural partitions • Traditionally classified into 4 basins

  3. Pacific Ocean • Deepest and largest • Challenger Deep in Mariana Trench • Almost as large as other 3 combined • Covers 30.5% of Earth’s surface area • 60,045,000 square miles • Larger surface area than all land on Earth

  4. Atlantic & Indian Oceans • About same average depth • Atlantic is larger in area • Atlantic = 20.8% of Earth’s surface area • 29,630,000 square miles • Indian = 14.4% • 26,463,000 square miles

  5. Arctic Ocean • Smallest and shallowest • 2.8% of Earth’s Surface area • 5,426,000 square miles

  6. The Southern Ocean • Continuous body of water that surrounds Antarctica • 7,846,000 square miles

  7. What are Seas? • Areas of salt water connected to oceans • Shallower than main ocean basins

  8. Features of the Sea Floor

  9. Sediment • 2 major types: • Lithogenous • Weathering of rock • Biogenous • Skeletons/shells of marine animals • Composed of either calcium carbonate or silica

  10. Continental Margins • Boundary between continental and oceanic crust • 3 sections: • Continental Shelf • Continental Slope • Continental rise

  11. Continental Shelf • Part of continent under water • Ranges from .6 miles – 470 miles • During ice age, shelf is exposed • Rich diversity of living things

  12. Slope and Rise • At shelf break, slope gets very steep • Descends down to deep sea • “Drop off” • Sediment moving from continent moves down submarine channels and accumulates at bottom of slope • Continental rise

  13. Continental Margin depends on Plate Tectonics • Active Margins • Area of geological activity • Trenches • Steep, rocky shorelines • Passive Margins • Inactive • Wide, gradually sloping shelf, thick continental rise

  14. Comparing Margins PASSIVE MARGIN ACTIVE MARGIN

  15. Deep-Ocean Features • Abyssal Plain • Relatively flat • Seamounts • Submarine volcanoes • May rise above surface & form islands • Guyots • Flat-topped seamounts

  16. Mid-Ocean Ridge • At center of ridge, tectonic plates are pulling apart • Central rift valley forms here • Contains many cracks • Hydrothermal Vents form • Deep, hot springs

  17. How Do We Know the Topography of the Ocean? • Sonar (sound navigation ranging) • Send sound down • It bounces off object/feature • Echo returns

  18. Using Sonar • Sound travels 1454 m/sec in water • To calculate depth: 1454 m/sec x time /2 • Ex. If sound is sent from vessel & returns 4 seconds later, what is the depth? 2,908 meters

  19. Improved Technology: Side Scan Sonar • Sound waves sent out at an angle • Measures strength of echo • Converts strength of echo into shades of gray

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