1. Layers of the Earth

2. Layers of the Earth Compositional Layers Structural Layers
Divided by what they are made out of
There are 3 Compositional Layers
Structural Layers
Divided by how they “work”
There are 5 Structural Layers

3. Compositional Layers (made out of)
Crust
Oceanic Crust
Thinner
Younger (180 million or less)
More dense
Continental Crust
Thicker
Older (up to 4 billion years old)
Less dense

4. Compositional Layers Mantle Core Under crust More dense than crust
2/3 of Earth’s total mass
Core
Central part of Earth
Made of Iron & Nickel

5. Structural Layers (work)
Lithosphere
Crust + Upper Mantle
Cool, Rigid
Makes up plates (tectonic)
Asthenosphere
Plastic (like clay)
Contains magma
Has convection currents which move the plates

6. Structural Layers
Mesosphere
“Middle” sphere
Solid mantle rock

7. Structural Layers Outer Core Inner Core Dense Liquid
Source of magnetosphere
Inner Core
Solid
1/3 of Earth’s mass

8. How do scientists “know” that the earth has these layers?

9. How about drilling? Continental Crust: Oceanic Crust:
The Kola Superdeep Borehole on the Kola peninsula of Russia reached km (~7.62 mi) and is the deepest penetration of the Earth's solid surface.
The dig began in 1970 and continued for 19 years, stopping only when the 180°C (356°F) temperature made further digging impossible
Oceanic Crust:
We have drilled down 1.7 km (~1 mi) into the seafloor.
We have penetrated only the upper 25% of either crust.

10. Why can’t we dig deeper?
HEAT: At 5 km deep, the temperature reaches 70 degrees Celsius (158 F) and therefore massive cooling equipment is needed to allow workers to survive at such depths. Remember the deepest hole reached 180°C (356°F).
ROCK WEIGHT: At 3.5 km the pressure of rocks above you is 9,500 tons per meter squared. When rock is removed through mining this pressure triples in the surrounding rock. This effect (coupled with the cooling of the rock) causes a phenomenon known as rock bursts, which accounts for many of the 250 deaths in South African mines every year.
PRESSURE OF MAGMA: Once you break through the crust, you would release pressurized magma– instant volcano – destroying equipment, killing workers, etc.

11. So – what “tool” do scientists use to learn about the layers…

12. Scientists use data from earthquakes – using seismometers – to learn about what is below us.

13. Seismograms