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Exploring the Deep

This lecture explores the dynamic nature of the Earth, including earthquakes, volcanic eruptions, and surface features such as mountain ranges and mid-ocean ridges. It also examines the topography of the ocean floor and the formation of ocean basins. The lecture discusses the interior of the Earth and how scientists gather information about it through meteorites, volcanoes, and seismic waves. It concludes with an overview of the Earth's layers and their properties.

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Exploring the Deep

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  1. GEO/OC103 Exploring the Deep Lecture 4: The Structure of the EARTH

  2. The Edge of the Sea • "Now I hear the sea sounds about me; • the night high tide is rising, swirling with a confused rush of waters against the rocks below …. • Once this rocky coast beneath me was a plain of sand; • then the sea rose and found a new shore line. • And again in some shadowy future the surf will have ground these rocks to sand and will have returned the coast to its earlier state. • And so in my mind's eye these coastal forms merge and blend in a shifting, kaleidoscopic pattern in which there is no finality, no ultimate and fixed reality - Earth becoming fluid as the sea itself." • Rachel Carson, The Edge of the Sea,  1955

  3. Atmosphere

  4. Hydrosphere Atmosphere

  5. Hydrosphere Atmosphere Cryosphere

  6. Biosphere Hydrosphere Atmosphere Cryosphere

  7. Lithosphere Biosphere Hydrosphere Atmosphere Cryosphere

  8. Our Dynamic Earth • Earth is incredibly dynamic • How do we know it’s dynamic?? • Earthquakes • Volcanic eruptions • Surface Features: • Mountain Ranges; Mid-Ocean Ridges; Deep-Sea Trenches

  9. Topography of the Ocean Floor

  10. Topography of the Ocean Floor Mid-Ocean Ridge

  11. Topography of the Ocean Floor Deep-sea Trench Mid-Ocean Ridge

  12. Topography of the Ocean Floor Deep-sea Trench Mid-Ocean Ridge Island Chain

  13. Elevated Continents

  14. Elevated Continents Depressed Ocean Basins

  15. How Big is the Earth? • Circumference  40,000 km (25,000 miles) • Radius  6,300 km (4,000 miles) • (1 meter = 1/10,000,000 distance from equator to pole)

  16. Questions: How are the ocean basins formed? How permanent are these features? What is the age of the ocean floor? Why are the ocean basins deep and the continents high?

  17. The Surface of the Earth • 2 levels: • elevated continents • depressed ocean basins • What causes these surface features? • We must know what goes on inside the Earth

  18. Interior of the Earth?

  19. Jules Verne

  20. “Journey to theCenter of the Earth” • Entered in Iceland • Exited in Italy

  21. Edgar Rice Burroughs • “Tarzan” • “John Carter of Mars”

  22. Pellucidar

  23. Information about the Earth’s Interior comes from: • Meteorites • Volcanoes • Seismic Waves

  24. Meteor Crater (Arizona)

  25. Willamette Meteorite • Found 1902,in West Linn • Largest inthe U.S.A. • Sold and nowresides atthe AMNH

  26. Volcanoes • E.g., Hawaiian “hotspot” • Windows into theEarth • Samples 200km down

  27. Seismic Waves • Sound energyfrom earthquakesand large explosions

  28. DEPTHS • Top of Mantle • 10 to 70 km (5 to 30 miles) • Top of Core • 2,900 km (2000 miles) • Center of Earth • 6,300 km (4,000 miles) • Mt. Everest  9 km high. • Mariana Trench 11 km deep.

  29. How do we know what’s inside the Earth?

  30. How do we know what’s inside the Earth?Direct Observations: • Exposures on Surface • Up from  50 km (30 miles) depth • Drilling • To  15 km (10 miles) • Volcanic Material • Up from  200 km (120 miles) depth

  31. How do we know what’s inside the Earth?

  32. How do we know what’s inside the Earth?Indirect Observations: • Magnetic Field • Iron core. • Gravity Field • Densities: • Crust: 2 - 3 gm/cm3 • Mantle: 3.3 - 5.8 gm/cm3 • Core: 10.8 gm/cm3 • Earthquake Seismic Waves • Physical state of crust, mantle, core.

  33. Interior of Earth by STRENGTH • LITHOSPHERE • rigid outer shell • crust and upper mantle (~ 50 to 200 km thick) • somewhat brittle, breakable • cold (likebutterout of fridge) • ASTHENOSPHERE • warmer, plastic layer under lithosphere • mantle from ~ 150 to 700 km • squishy, plastic • warm (like softened butter) • LOWER MANTLE • Solid, but can flow over time! • ~700 to 2900 km • OUTER CORE • liquid • INNER CORE • solid

  34. Elevated Continents Depressed Ocean Basins

  35. Swimming Pool

  36. Earth’s Mantle

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