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Introduction to Earth Science

Introduction to Earth Science. Or, How The Earth Works. Branches of Earth Science. Geology Solid Earth Much Larger than Other Parts Many More Kinds of Materials Preserves a History Meteorology – Climatology Oceanography Astronomy Planetary Geology. The Earth Systems.

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Introduction to Earth Science

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  1. Introduction to Earth Science Or, How The Earth Works

  2. Branches of Earth Science • Geology • Solid Earth Much Larger than Other Parts • Many More Kinds of Materials • Preserves a History • Meteorology – Climatology • Oceanography • Astronomy • Planetary Geology

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

  4. The Solid Earth

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

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

  7. 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

  8. Surface Currents

  9. Thermohaline Circulation

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

  11. Hydrologic Cycle

  12. 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

  13. 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

  14. The Rock Cycle

  15. 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

  16. Plate Tectonics

  17. Plate Tectonics and Resources

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

  19. 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

  20. 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.

  21. 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.

  22. 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

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

  24. Scientific Principles in Geology • Parsimony (Keep It Simple) • Superposition • Uniformitarianism Using these, plus observation, we establish facts about Earth Processes

  25. 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.

  26. Superposition:Road Cut, Superior, AZ

  27. Geologic Map

  28. 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

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