Earth’s Layers

A journey to the center of the earth...

The Four Layers

•The Crust•The Mantle

•The Outer Core•The Inner Core

The Four Layers

The Crust

• The outer most layer of the earth.• The thinnest layer of the earth.

– Continental Crust – 30-40 km (18-25 mi)

– Oceanic Crust – 5 km (3 mi)

• The crust is the layer we live on.

Transition Zone

•The Lithosphere–Consist of the lower part of the crust

and the upper part of the mantle.- 100 km thick

The Mantle

• The second layer of the earth.• The thickest layer.

– 2885 km (1790 mi)

• Two parts of the mantle– The upper mantle

•The asthenosphere

– The lower mantle•semisolid of super hot rock

The Asthenosphere

• It Moves!– This layer is cooler than the lower

mantle below it, 1000oC.•This is the temperature at which rock

begins to melt.

– The lower mantle is 3700oC.•The temperature difference causes

convection currents to form.

Convection in the Mantle

•What is convection?–Have you ever boiled water?–Have you ever made soup?–Then you have seen and used convection.

Convection in the Mantle

• Convection occurs when the hotter material at the bottom rises to the top.

• At the top the material cools and becomes denser.

• The material sinks to the bottom and heats again.

Convection in the Mantle

• The material becomes hotter and less dense and rises to the top.

• This cycle repeats over and over slowly causing the mantle to move.

Convection in the Mantle

The Outer Core

•The third layer.•Composed of liquid metal.

– Iron and nickel.

•This liquid metal spins in one direction.

•2270 km (1400 mi) thick.•Very hot - 3700oC-4300oC

The Inner Core• The fourth layer.• Solid metal ball of iron.• The hottest layer.

–4300oC• Wait, if it is the hottest layer than

why is it solid?–The pressure is so high that it

compresses this layer into a solid.

Resources

• http://www.cotf.edu/ete/modules/volcanoes/interior.html

• http://www.learner.org/channel/courses/essential/earthspace/session3/closer.html

• http://www-astronomy.mps.ohio-state.edu/~pogge/TeachRes/Artwork/Stars/

• http://www.lacoctelera.com/myfiles/walksearthscience/sx5561a3.jpg