Earth's Layers

• Earth is made up of layers.

• The materials that make up each layer have different properties.

• As you travel deeper into the Earth, the pressure and temperature increase.

• Scientists think about Earth's layers in two ways - in terms of their chemical composition and in terms of their physical properties.

Earth's Compositional Layers

Crust

• Outermost layer of Earth.

• Two types - oceanic and continental.

• Mostly made of the elements oxygen and silicon.

Mantle

• Region of hot, slow moving, solid rock.

• Convection currents occur here.

• More dense than the crust because it contains more magnesium.

Core

• Centermost part of Earth.

• The thickest compositional layer.

• Earth's densest layer.

• Mostly made of the elements iron and nickel.

Earth's Mechanical/Structural Layers

Lithosphere

• Outermost rigid layer of Earth.

• Made up of the crust and the upper part of the mantle.

• Divided into pieces called tectonic plates.

Asthenosphere

• Upper part of the mantle that is made of semisolid rock.

• Flows slowly.

• Convection currents occur her causing tectonic plates to move.

Mesosphere

• Strong lower part of the mantle.

• Flows slower that the asthenosphere.

Outer Core

• Liquid layer of Earth's core.

• Surrounds the inner core.

• Made of liquid iron and nickel.

Inner Core

• Solid, dense center of Earth made of iron and nickel.

• Although the inner core is very hot, it is kept solid due to the great pressure of the layers above it.

• About 6,380 km below Earth's surface.

Layers of the Earth: Composition & Mechanical