Layers of the Earth

The Earth is comprised of 4 different layers. These layers include the crust, mantle, outer core, and inner core.

1. Crust

• The outermost, thinnest layer of the Earth.

• Varies from about 5 km (oceanic crust) to 70 km (continental crust)

  • Oceanic Crust: Made of basalt, denser than continental crust.

  • Continental crust: Composed mainly of granite, less dense.

• Divided into tectonic plates

• Earthquakes and volcanic activity happen

• Contains all life forms, landforms, and bodies of water.

2. Mantle

   • Thickest layer, below the crust

   • 2,900 km in thickness

   • Made of solid, silicate rock, rich in magnesium, iron, silicon, and oxygen

   • Mostly solid rock, but behaves like a viscous fluid over long periods, and forms convection currents due to the heat from the core.

   • Ranges from 500°C near the crust to over 4,000°C near the core.

     • Convection Currents

       • Convection Current = Hot substances rise, and cool substances sink, causing a cycle of movement

       • Heat makes something less dense = lighter

       • Cooling makes something more dense = heavier

     • Convection Currents in the Mantle

3. Outer Core