1. Marine Science Unit 3: Geological Oceanography

3. Earth’s Interior Notes
What’s the Earth like inside?

4. Layers of the Earth
The earth is made up of layers that formed from differences in density.
Inner Core
Outer Core
Mantle
Crust
Let’s look at them…

5. The Layers of the Earth
The Earth is composed of four different 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 even hotter with pressures so great you would be squeezed into a ball smaller than a marble if you were able to go to the center of the Earth
© Copyright 2006.  M. J. Krech. All rights reserved.

6. Layers of the Earth The Core - Discovered 1906
innermost layer; solid inner core and liquid outer core; iron-rich.
Made up of 90% iron and nickel with some silicon, sulfur, and other heavy metals
Temperature of 5,500° C (9,032° F)
The total core has an estimated radius of 3470 km
The core makes up 31.5% of the Earth’s mass and 16% of the Earth’s volume.

7. Layers of the Earth Inner Core- Discovered 1936
Thought to be solid iron and nickel due to intense pressure
5000° C; but new evidence suggests can get as hot as 6,600 ° C (hotter than the sun)
1,200 km thick
Density- 15 g/cm3

8. Layers of the Earth Outer Core- Discovered 1926
Liquid iron and nickel and has less pressure than the inner core
2200° C – 5000° C
2,250 km thick
Density- 10 g/cm3

9. Layers of the Earth Mantle Core (Lower and Upper)
Largest layer of the Earth
Made of Si, O, Fe, and Mg.
870° C to 2200° C
2,900 km thick
Density- 5 g/cm3
Makes up 68% of the Earth’s mass and 82% of the Earth’s volume

10. Layers of the Earth Lower Mantle Extends from the core
More dense than Upper Mantle and flows more slowly
Upper Mantle
Made up of two layers
1. Asthenosphere (asthenes=weak): partly melted and plastic.
Plasticity- the ability for a solid to flow like a liquid. Think asphalt.
Slowly flowing below the lithosphere extending to a depth of km
Density 3.5 g/cm3
2. Lithosphere (lithos=rock): Earth’s cool rigid outer layer that is km thick
Made up of the rigid solid upper portion of the mantle and the crust

11. Layers of the Earth Crust- outermost layer; thinnest portion of the
Thin solid outermost layer
Relatively cool temperature
0.4% of Earth’s mass and 1%
of Earth’s volume
Composed of oxygen,
silicon, magnesium, and iron
Oceanic Crust: Thin and made up of mostly basalt (heavy dark colored rock); 3-5 miles thick; denser than continental crust
Continental Crust: 25 miles thick and made up of mostly granite (light-colored rock)
The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other three layers. The crust is only about 3-5 miles (8 kilometers) thick under the oceans (oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust).

12. Analogy How are the earth’s layers similar to an egg? Shell=crust
Egg white=mantle
Yolk=core

13. How do we know what’s inside the Earth?
We use seismic waves to take an x-ray of it
Earthquakes: produce different types of seismic waves that can be detected far from the epicenter (origin).
P-waves: travel through solids and fluids (denser=faster)
S-waves: slower travel through solids only