2. Internal Structure of the Earth

Crust

Crust

• Outermost, thinnest layer

  Composed of rocks and minerals

  • Iron (Fe), Calcium (Ca), Hydrogen (H), Aluminium (Al), Silicon (Si), Oxygen (O), Sodium (Na), Potassium (K), Titanium (Ti)

• Continental crust - Thicker, lower density

• Oceanic crust - Thinner, higher density

Mantle

• Beneath the crust

• Composed of mostly silicates, namely Silicon (Si), and Oxygen (O)

• Convection current is present

  • Hot air rises

  • Cold air sinks

Outer Core

• Composed of Nickel and Iron

• Liquid

  • Liquid because there is not enough pressure for it to be kept solid

Inner Core

• Composed of Nickel and Iron

• Solid

• Intense pressure -- prevents the iron in the core from melting

Lithosphere

• Solid, outer part of the Earth

• Rigid and elastic layer (upper mantle and crust)

  • Rigid due to stress, temperature, and curvature of the Earth

• Coolest layer (literally.)

• Conducts heat from convection

Oceanic lithosphere

Thinner and denser oceanic crust. Primarily composed of basalt.

Continental lithosphere

Thicker and less dense continental crust. Primarily composed of granite.

Characteristics of a plate

• Carries both continental and oceanic crusts

• Floats on top of the asthenosphere -- slides horizontally over it, bends slightly

• Moves very slowly

Asthenosphere

• Highly viscous -- Rocks flow like liquid (Magma)

• High pressure and temperature

7 Major Plates

African, Antarctic, Eurasian, Indo-Australian, North American, Pacific, South American

Examples of Minor Plates

Caribbean, Scotia, Arabian, India, Philippine, Juan de Fuca, Cocos, Nazca Plates