Science

Crust

  • broken into big pieces, like a gigantic jigsaw puzzle

  • also known as tectonic plates

  • Made of relatively light elements, silica, aluminum and oxygen.

Mantle

  • Close to 3,000 kilometers thick, Earth’s thickest layer

  • Made of Iron, Magnesium, and Silicon

  • Dense, hot, and semi-solid

  • reaches the melting point of rock, forming layers of partially melted rock known as the asthenosphere.

Outer Core

  • Made from iron and nickel, liquid form.

  • Heated largely by the radioactive decay of the elements uranium and thorium.

Inner core

  • Solid metal ball, radius of 1,220 km.

  • Extremely dense, made mostly of iron and nickel

  • very hot


  • Conorod discontinuity - upper & lower crust

  • Mohorovicc discontinuity - lower crust & upper mantle / Andhrija Mohovicic - using Seismic waves

  • Repiti discontinuity - upper & lower Mantle

  • Guttenberg discontinuity - Lower Mantle & Outer core

  • Lehmann discontinuity - outer & inner core

Alfred Wegener

  • Father of Plate tectonics

  • Continential Drift


    Driving Forces Resisting Forces

  • Slab pull Slab resistance

  • Slab suction Collisional resistance

  • Ridge push Transform fault resistance

  • Mantle convection Drag force


    Seismometers is used to detect seismic waves and is recorded by seismographs.


    Body waves and surface waves

  • Body waves - travel through the inner layers of the planet

    • Surface waves - only on the surface.


      P waves - first to be felt

      S waves - felt in an up and down motion


      Pangaea - greek word / pan - all / gea - earth - all of earth

      surrounded by vast sea or super ocean called Panthalassa - all seas

    • broke into 2 smaller super continents, Gondwana and Laurasia




      Contraction theory - contracted and wrinkled


      Theory of continental drift

    • apparent fit of the eastern coastline of South America and western coastline of Africa

    • Similarities of plant and animal fossils in South America and some parts of the African continent.

    • Similarities in the sequences of rock layers of opposite sides of the Atlantic Ocean


      Seafloor spreading theory

    • Proposed by Harry Hess

    • seafloors move and carry the continents along

Theory of plate tectonics

  • incorporates the continental drift theory and the seafloor spreading theory.

Driving Forces

  • Mantle convection - rising of heat from the core toward the mantle

  • Slab pull - subducting slab sinks into the hot mantle because of a difference in temperature.

  • Slab suction - two colliding plates, one subducting underneath the other.

  • Ridge push — lithosphere is pushed up by the asthenosphere.

Resisting Forces

  • Slab resistance - force that resists all the forces associated with plate movement in subduction zones

  • Collisional resistance - heavy plate is pulled into the mantle

  • Transform fault resistance - frictional force due to the opposing movement of plates moving past one another between two spreading centers.

  • Drag force - resists movement of lithospheric plates.