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The Sea Floor

The Sea Floor. Origin of the Ocean. Water vapor released during degassing of early earth volcanism Salt from chemical weathering. Methods of Studying the Sea Floor. Rock Dredge Corer Sea-Floor Drilling Submersibles Echo Sounder Seismic Profiler

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The Sea Floor

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  1. The Sea Floor

  2. Origin of the Ocean • Water vapor released during degassing of early earth • volcanism • Salt from chemical weathering

  3. Methods of Studying the Sea Floor • Rock Dredge • Corer • Sea-Floor Drilling • Submersibles • Echo Sounder • Seismic Profiler • Surveys - Magnetic, Gravity, Seismic Refraction • Deep Sea Cameras

  4. Features of the Sea Floor • Continental Margins • Passive • Active • Oceanic trench • Mid-oceanic ridge • Seamounts

  5. Continental Shelves and Continental Slopes • Vertical exaggeration in diagrams • Continental shelf • Continental slope • Continental rise

  6. Active Continental Margins • On land- earthquakes, young mountain belt, volcanoes • Continental shelf, continental slope, oceanic trench • Oceanic Trenches • Earthquakes of the Benioff seismic Zones • Volcanoes • Low Heat Flow • Negative Gravity Anomalies

  7. Submarine Canyons • Abyssal Fans • Bottom Currents • Down-canyon movement of sand • Bottom currents • River erosion • Turbidity Currents • Graded bedding • Shallow water fossils

  8. Passive Continental Margins • Continental shelf, slope, rise • The Continental Rise • Types of Deposition • From turbidity currents • From contour currents • Abyssal plains

  9. Fracture Zones • Offset rift valleys • Transform Fault • Portion that has earthquakes

  10. Seamounts, Guyots, and Aseismic Ridges • Seamounts • Guyots • Aseismic ridges

  11. Reefs • Fringing Reefs • Barrier Reefs • Atolls

  12. Sediments of the Sea Floor • Terrigenous Sediment • Pelagic Sediment • thickness increases away from crest of mid-oceanic ridge

  13. Deep-sea sediments, those found at depths greater than about 500 m, cover roughly two-thirds of the Earth. The predominant deep sediment is carbonate ooze, which covers nearly half the ocean floor

  14. The Mid-Oceanic Ridge • Rift Valley • Geologic Activity on the Ridge • Shallow-focus Earthquakes • High Heat Flow • Basalt Eruptions • Hot springs • Black Smokers • Biologic Activity on the Ridge • Geomicrobiology

  15. Oceanic Crust and Ophiolites • Evidence for composition of the oceanic crust • Ophiolite (from top to bottom) • Marine sedimentary rock • Pillow basalt • Sheeted dike complex • Gabbroic intrusions • Ultramafic rock

  16. The Age of the Sea Floor • Younger than 200 million years old • Parts of continents much older

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