The Earth

1
The Earths Layers
2

The Earth has 4 Layers

• The Crust is the layer that you live on, and it
  is the most widely studied and understood.
• The Mantle is much hotter and has the ability to
  flow.
• The Outer Core and Inner Core are hotter still
  and are under enormous pressure.

3
Crust
Continental Crust
Oceanic Crust

• The Earth's Crust is like the skin of an apple.
  It is very thin in comparison to the other
  layers.
• The crust is 5-100 km. thick
• There are two types of crust Continental Crust
  and Oceanic Crust
• Both continental crust and oceanic crust are made
  of the elements oxygen, silicon, and aluminum.

4
Crust

• The temperature of the crust varies from air
  temperature at the top to 900? C. at the bottom
  (hot enough to melt rock!)

5
Mantle

• The mantle is the thickest layer of the Earth,
  2900 kilometers thick.
• Very hot, dense rock like asphalt under a heavy
  weight.
• The temperature of the mantle varies from 900?
  Celsius at the top to about 3000? Celsius near
  the bottom!

6
The Mantle

• No one has ever visited the mantle.
• With present technology, we cant drill far
  enough through the crust to get to the mantle.
• So how do scientists know about the mantle?
• They observe places where mantle rock pushes
  close to the Earths surface, such as where lava
  pours out of active volcanoes on the ocean floor.

7
Convection Currents in the Mantle

• Convection currents are caused by the very hot
  material at the deepest part of the mantle
  rising, then cooling, sinking again and then
  heating, rising and repeating the cycle over and
  over.
• When the convection currents flow in the mantle
  they also move the crust. The crust gets a free
  ride with these currents.
• The movement of the mantle is the reason that the
  plates of the Earth move!

Convection Current Animation http//education.sdsc
.edu/optiputer/flash/convection.htm http//www.abs
orblearning.com/media/item.action?quick12p
8
The Core

• The core of the Earth is like a ball of very hot
  metals. 3000? C. to 4000? C.
• Iron small amounts of nickel
• The Earths magnetism is caused by the core.

9
Outer Core

• The outer core is so hot that the metals in it
  are all in the liquid state.
• 2000 km thick
• Liquid metals (iron nickel)

10
Inner Core

• Temperatures and pressures are so great here that
  the iron and nickel metals are squeezed together
  and vibrate in place as a solid.

11
Pressure

• In the core, the pressure is 45,000,000 pounds
  per square inch.
• You would be squeezed into a ball smaller than a
  marble if you were able to go to the center of
  the Earth!

12

• On lined paper in your science binder, copy these
  questions and answer them in complete sentences
• What causes the mantle to "flow"?
• What are the two main metals that make up the
  Earths core?
• How do temperatures and pressures change as you
  move from the crust toward the core?