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Geology 12

Geology 12. Presents. Unit Outline Chp 10 Earth’s Interior Chp 11 Sea Floor Chp 12 Plate Tectonics Chp 9 Seismic (EQ) Chp 13 Structure. Chp 11 Seafloor. Volcanoes outgasses water to fill oceans Average depth = 4 km Continental Margins mark edge of continent from deep sea floor

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Geology 12

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  1. Geology 12 Presents

  2. Unit Outline • Chp 10 Earth’s Interior • Chp 11 Sea Floor • Chp 12 Plate Tectonics • Chp 9 Seismic (EQ) • Chp 13 Structure

  3. Chp 11 Seafloor • Volcanoes outgasses water to fill oceans • Average depth = 4 km • Continental Margins mark edge of continent from deep sea floor • 2 types of margins

  4. Cont’l Shelf Cont’l Slope Abyssal Plain Cont’l Rise Submarine canyon Oceanic Plate Cont’l Plate 1. Passive Margin = where oceanic plate is fused to continental plate and large amount of sediment is deposited. • Ex: Eastern N. America Cont’l Margin fused

  5. Submarine canyons • Cut into cont’l shelf-slope by: • a) rivers when sea-level was up to 130 m lower during ice ages • animation • b) turbidity currents = underwater landslides that erode slope and travel for 100’s of km • Sediments are deposited as a deep sea fan as graded bedding

  6. Passive Margins

  7. New York Cont’ shelf Hudson River Submarine Canyon Cont’ slope

  8. 2. Active Margin = where oceanic plate is subducting under continental plate Ex: W. coast of S. America Volcano Cont’l shelf Cont’l slope Trench Abyssal plain Cont’l plate Oceanic plate

  9. Active Margins

  10. Oceanic (spreading) Ridge: where new oceanic plate is being created by volcanism Island/seamount seamounts Rift valley Pillow lava Sheeted dikes and gabbro mantle peridotite

  11. Ocean Ridge

  12. Guyot • Guyots New volcanic island Eroded flat by waves

  13. Guyots & Seamounts

  14. Guyots & Seamounts

  15. Reefs Top view lagoon Fringing reef Barrier reef Cross section Atoll

  16. Fringing Reef Island

  17. Barrier Reef Island

  18. Atoll

  19. Islands get smaller as they age due to: • a) wave erosion • b) oceanic plate sinks as it moves way from divergent boundary or hot spot • See Q14d, p.9 of WS 12.2

  20. Use the diagram of a typical ocean basin to answer question6. 6. The diagram represents a cross-section of an ocean basin. The number which represents a diverging plate boundary is A. 1 B. 2 C. 3 D. 4

  21. Read Chapter 11Do WS 11.1Read Chapter 12 Go to Chp 12 Plate Tectonics

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