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How The Earth Works

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How The Earth Works

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How The Earth Works

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  1. How The Earth Works

  2. The Solid Earth

  3. Earth Systems • External Effects (Astronomical) • Atmospheric Circulation • Oceanic Circulation • Hydrologic Cycle • Rock Cycle • Plate Tectonics

  4. Earth Systems

  5. Earth Systems

  6. Earth Systems

  7. Earth Systems

  8. Earth Systems

  9. Earth Systems

  10. Earth Systems

  11. Earth Systems

  12. Convection

  13. Earth and the Universe • Rotation (Day-Night) • Lunar (Tides) • Annual (Seasons) • Precession and Orbit Variations (Ice Ages?) • Galactic (250 m.y. period) • Unpredictable Events • Nearby Supernovae • Meteor Impacts • Long-Term Evolution of Sun

  14. Atmospheric Circulation • Unequal Solar Heating • Equator to Pole • Day - Night • Different Surfaces • Buoyancy • Adiabatic Heating and Cooling • Coriolis Effect • High and Low Pressure • Fronts and Air Masses

  15. Atmospheric Circulation

  16. Oceanic Circulation • Surface Currents - Driven by Winds • Thermohaline - Deep Circulation • Evaporation makes water more saline and denser • Freezing makes water more saline and denser • Cold water is denser than warm water

  17. Surface Currents

  18. Thermohaline Circulation

  19. Hydrologic Cycle • Evaporation from Oceans • Precipitation on Land • Infiltration into Ground (Ground Water) • Runoff (Erosion)

  20. Hydrologic Cycle

  21. Water • Principal Agent in Modifying Earth’s Surface • Medium for Storing and Distributing Global Heat • The Universal Solvent • Essential for Life • Destructive to Rocks • Lowers Melting Point of Rocks • Reduces Strength of Rocks Under Pressure

  22. The Rock Cycle • New Rocks Exposed by Erosion • Rocks Broken Down Mechanically and Chemically (Weathering) • Components Transported by Erosion • Components Cemented into Sedimentary Rocks • Burial and Heating creates Metamorphic Rocks • Melting Creates Igneous Rocks

  23. The Rock Cycle

  24. Plate Tectonics • Outer Crust of Earth Moves a Few cm/yr • Driven by Convection in Earth’s Interior • Accounts For: • Earthquakes • Volcanoes • Mountain-Building (Orogeny) • Configuration of Continents

  25. Plate Tectonics

  26. Plate Tectonics

  27. Convection

  28. Convection In The Earth

  29. Plate Tectonics and Resources

  30. Configuration of Continents • Oceanic Circulation • Weather and Climate Patterns • Deserts • Mountains and Rain Shadows • Pathways for Migration • Ecological Niches

  31. Configuration of Continents

  32. Some Unique Aspects of Geology Importance of Relationships • Sequential • Spatial Importance of Time Distinctive Problems of Evidence • Slow Rates • Rare Events • Destruction of Evidence • Inaccessibility

  33. Some Geologic Rates Cutting of Grand Canyon • 2 km/3 m.y. = 1 cm/15 yr Uplift of Alps • 5 km/10 m.y. = 1 cm/20 yr. Opening of Atlantic • 5000 km/180 m.y. = 2.8 cm/yr. Uplift of White Mtns. (N.H.) Granites • 8 km/150 m.y. = 1 cm/190 yr.

  34. Some Geologic Rates Movement of San Andreas Fault • 5 cm/yr = 7 m/140 yr. Growth of Mt. St. Helens • 3 km/30,000 yr = 10 cm/yr. Deposition of Niagara Dolomite • 100 m/ 1 m.y.? = 1 cm/100 yr.

  35. 1 Second = 1 Year • 35 minutes to birth of Christ • 1 hour+ to pyramids • 3 hours to retreat of glaciers from Wisconsin • 12 days = 1 million years • 2 years to extinction of dinosaurs • 14 years to age of Niagara Escarpment • 31 years = 1 billion years

  36. Some Unique Aspects of Geology (Continued) Reliance on Inference and Deduction Intrinsically "Unsolvable" Problems • Ancient Landscapes • Mass Extinctions • Ancient Ocean Basins

  37. Scientific Principles in Geology • Parsimony (K.I.S.S.) • Superposition • Uniformitarianism Using these, plus observation, we establish facts about Earth Processes

  38. Parsimony • The simplest explanation that fits all the data is preferred • Doesn’t guarantee that things must be simple! • Theories with lots of ad hoc or unsupported ideas are probably wrong.

  39. Superposition:Mindoro Cut, Wisconsin

  40. Geologic Map

  41. Uniformitarianism Continuity of Cause and Effect • Apply Cause and Effect to Future - Prediction • Apply Cause and Effect to Present - Technology • Apply Cause and Effect to Past - Uniformitarianism