The Earth's Layers

The Crust

  • The Crust is the layer that we live on
  • The crust coolest layer of the Earth and the most solid
  • It is the most studied layer and the thinnest
  • Humans have never drilled through the entire crust
  • There are two types of crust. Oceanic crust and Continental crust
    • Continental crust is thicker and mostly made of granite
    • Oceanic crust is thinner and mostly made of basalt
    • Oceanic crust is thicker than continental crust

 

The Mantle

  • The mantle is the layer of the Earth between the crust and the core
  • It is not liquid like many people think. it flows but it is technically a solid. It is a semisolid
  • The lithosphere contains the crust and the upper part of the mantle
  • The asthenosphere sits just below the lithosphere and is much softer.
  • The Mantle is the thickest of all the layers

Mantle Convection

  1. Heat from radioactive decay in the Earth’s core heats up the mantle

   

  1. the hot material rises because it is less dense
    1. the hot mantle takes the plates with it as it moves
    2. the hot mantle cools and starts to sink
    3. The cooled mantle material pulls crust under the surface
    4. The mantle sinks toward the core to be reheated and the cycle starts again
  • When the convection currents flow in the asthenosphere they also move the crust.

Lithospheric Plates

  • The lithosphere is not one singular piece covering the whole Earth.
  • The lithosphere is broken up into many large moving slabs called “plates”

 

The Outer Core

  • The outer core is the only liquid layer of the Earth and it mostly made up of iron and nickel
  • As the Earth spins, the liquid iron and nickel of the outer core spin too
    • The spinning generates the Earth’s magnetic field that protects us from much of the Sun’s charged particles
    • Without the Outer Core being liquid, Earth would likely be as barren and lifeless as Mars

The Outer Core

  • The inner core is the center, and hottest layer of the Earth
  • The inner core of the Earth has temperatures and pressures so great that the metals are squeezed together and are not able to move about like a liquid, but are forced to vibrate in place like a solid.