Plate Tectonics

• Volcano - any opening in the ground where magma or molten rocks comes out
• ocean ridges - chain of volcanoes at the seafloor
• Fault - a break in the ground along which movement has taken place
• Trenches - deep canals on seafloor
• crust - thin outer layer (where people live)
• mantle - lies between earth's dense core and thin outer layer, below the crust
• core - center of the earth (ball shaped)
• the crust and the uppermost portion of the mantle have similar physical properties; they are solid and rigid.
• the earth is divided into layers based on its chemical composition; crust, mantle and core
• lithosphere - hard and rigid outer layer of the earth. (also includes the crust and asthenosphere)
• Moho Boundary - does not exist at uniform depth
• Mohorovicic Discontinuity - division in between crust/mantle
• Earth's Crust is divided into two types

  • Continental - SiAl (silicate aluminum)
  • Oceanic - SiMa (silicate magnesium)
• Continental crust is also created by plate tectonics
• Oceanic crust is formed at mid ocean ranges and it is destroyed in subduction zones
• Crust physical properties is solid
• Mantle physical properties are plastic and solid
• Convection Current - contributes into the landscape of the earth
• Outer core - mostly composed of iron and nickel
• Inner core - hot dense ball of mostly iron
• D layer - lowermost portion of mantle
• Volcanoes - windows of the earth
• Volcanoes erupt by heat and pressure
• Hotspot - usually located within the plates or away from margin
• Plate Boundaries - the lines between the pieces of plates are their boundaries
• Divergent - when plates move past by each other
• Transform - when plates slide past each other
• Shear Zone - area where the sliding plates meet
• Subduction - process by which the denser plate sinks into the mantle beneath the less dense plate
• Subduction plate - the place where two lithospheric plates come together
• Convection - method of heat transfer
• Slab Pull theory - explains gravity tends to "pull" denser or heavier material
• Raisin theory - earth is compared to a grape that has shrunk into raisin

  James Hall - proposed the raisin theory
• Isostasy theory - supported the raisin theory which refers to the gravitational equilibrium being experience by earth surface
• Clarence Edward Dutton - introduced the concept of isostasy
• Theatrum Orbis Terrarum (thetre of the earth) - considered the first true atlas
• Abraham Ortelius - made the theatrum orbis terrarum
• Continental Drift theory - implied the continents came from a single landmass
• Alfred Wegener - proposed the continental drift theory
• Seafloor Spreading theory - revived the continental drift theory, a hot less dense material from the mantle

  Harry Hess - proposed the seafloor spreading