exo & endo

• Plate Tectonics

  The Hadean Earth was once an undifferentiated, homogeneous mass of solid rock around 4.5 billion years ago. It began to sort out its materials based on density, resulting in distinct layering: crust, mantle, and core
• Types of Earth's crust

  • Continental
  • Oceanic
• Continental crust


  • Less dense, made of older material like silica and aluminum-based granite, divided into lithosphere and asthenosphere
• Oceanic crust


  • Denser, younger, and thinner, made of silica and magnesia-based basalt
• Plate Boundary

  Divergent boundary creates new plate material and normal faults. Convergent boundary causes plates to collapse, forming volcanic arcs and reverse faults. Transform boundary plates slide past each other, forming strike-slip faults
• Plate Movement

  • Factors include mantle convection, slab pull, and ridge push, resulting in tectonic movement of a few centimeters per year
• Mantle Convection


  Thermodynamic heating of liquid rocks in the mantle provides movement to the plates
• Slab Pull

  Tensional force exerted by cold, dense oceanic plates as they subduct into the mantle due to their weight, working with mantle convection
• Ridge Push

  Gravitational sliding occurring at mid-ocean ridges as the lithosphere slides down the asthenosphere
• The combination of mantle convection, slab pull, and ridge push results in tectonic movement of a few centimeters per year, almost invisible to people
• The Wilson Cycle is a theory proposed by John Tuzo Wilson, correlating plate movements
• Ocean ridges


  Result of the lithosphere sliding down the asthenosphere
• Tectonic movement


  A few centimeters per year, making it almost invisible to people
• The Wilson Cycle is a theory proposed by John Tuzo Wilson
• Wilson stated that the countless cycles of rifting and deformations that formed continents and ocean basins destroy older basins
• Wilson's theory justifies why the Earth has not shrunken nor expanded
• Wilson Cycle

  1. Continent Rifting

  2. Oceanic Basin and Crust Development

  3. Passive Margin Cooling and Sedimentation

  4. Volcanic Mountain Belt Formation

  5. Subduction Welding

  6. Continental Collision

  7. Orogenesis
• Continental Drift theory is proposed by Wegener
• Wegener suggested that the early Earth was once a supercontinent named Pangaea, surrounded by a superocean named Panthalassa
• Evidence used by Wegener to support Continental Drift theory

  • The Fit of Continental Shorelines
  • Distribution of Glacial Sediments
  • Paleoclimate
  • Fossil Distribution
  • Rock Distributions
• Wegener used the Fit of Continental Shorelines, Distribution of Glacial Sediments, Paleoclimate, Fossil Distribution, and Rock Distributions as pieces of evidence