How The Earth Works

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How The Earth Works
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(No Transcript)
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The Solid Earth
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Earth Systems

• External Effects (Astronomical)
• Atmospheric Circulation
• Oceanic Circulation
• Hydrologic Cycle
• Rock Cycle
• Plate Tectonics

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Earth Systems
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Earth Systems
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Earth Systems
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Earth Systems
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Earth Systems
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Earth Systems
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Earth Systems
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Earth Systems
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Convection
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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

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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

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Atmospheric Circulation
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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

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Surface Currents
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Thermohaline Circulation
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Hydrologic Cycle

• Evaporation from Oceans
• Precipitation on Land
• Infiltration into Ground (Ground Water)
• Runoff (Erosion)

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Hydrologic Cycle
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Water

• Principal Agent in Modifying Earths 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

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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

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The Rock Cycle
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Plate Tectonics

• Outer Crust of Earth Moves a Few cm/yr
• Driven by Convection in Earths Interior
• Accounts For
• Earthquakes
• Volcanoes
• Mountain-Building (Orogeny)
• Configuration of Continents

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Plate Tectonics
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Plate Tectonics
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Convection
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Convection In The Earth
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Plate Tectonics and Resources
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Configuration of Continents

• Oceanic Circulation
• Weather and Climate Patterns
• Deserts
• Mountains and Rain Shadows
• Pathways for Migration
• Ecological Niches

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Configuration of Continents
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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

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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.

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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.

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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

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Some Unique Aspects of Geology (Continued)

• Reliance on Inference and Deduction
• Intrinsically "Unsolvable" Problems
• Ancient Landscapes
• Mass Extinctions
• Ancient Ocean Basins

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Scientific Principles in Geology

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

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Parsimony

• The simplest explanation that fits all the data
  is preferred
• Doesnt guarantee that things must be simple!
• Theories with lots of ad hoc or unsupported ideas
  are probably wrong.

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SuperpositionMindoro Cut, Wisconsin
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Geologic Map
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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