1. Unit 1: Introduction to Earth Science part 3
Segregation/Formation Of Earth’s Layers

2. Origin of the earth
It was thought that Earth was not always layered as it is today. Some scientists suggest that Earth was somewhat like the moon billions of years ago

3. Why does earth have layers?

4. Why does earth have layers?
Thanks to nature (i.e. heat and gravity)
Sources:
Radioactive Decay
Particle Collisions
Residual Heat
Related to density

5. Why does earth have layers?
Heat: from particle collisions and radioactive elements produced melting of the interior.
Denser material sank to the Earth’s center (due to gravitational forces)
lighter materials floated upwards.
This process is often referred to as differentiation or segregation.
*still occurring today (smaller scale)

6. Why does earth have layers?
Gases are released from Earth’s interior through volcanoes.
This segregation/differentiation caused the geosphere (Solid Earth) to developed layers that have different properties.

8. Differentiation Video

9. Layers of the earth
Both the inner and outer core are made up of Nickel and iron (due to segregation),
but they have different States of Matter.
Why would they be in different states?
One solid, one liquid
Which would be solid;
the inner or outer core? Why?

10. Layering of Earth pg. 22, 476

11. State: Thin, rocky outer skin
Crust
Lithosphere
State: Thin, rocky outer skin
Composition: felsic rock - granite is dominant rock
Density: 2.7 g/cm3 (mostly low density rock)
Temperature: increases with depth 400 C
*Roughly 100km think (varies depending on ocean or continental) -

14. Plate tectonics

15. Temperature: increases with depth to 3500 C.
Asthenosphere (upper mantle)
Mantle
State: Mainly solid, very strong but can flow (like silly putty or an eatmore bar)
Composition: Dominant rock is ultramafic - Dominant rock type is called ‘peridotite”
Density: 3.3 g/cm3 (increases in density as it goes deeper-segregation)
Temperature: increases with depth to 3500 C.
*Is 2900 km thick – The thickest layer!

16. Composition: iron and a small amount of nickel Density: 11 g/cm3
Outer Core
State: liquid
Composition: iron and a small amount of nickel
Density: 11 g/cm3
Temperature: > 6700 C
* 2270 km thick
- convection currents exist within and contributes to origin of magnetic field

17. *Hotter, denser and stronger that outer core **State: solid
Inner Core
*Hotter, denser and stronger that outer core
**State: solid
Radius = 1216 km

19. Temperature and Density Increases with Depth
Density inside Earth increases as depth inside Earth increases.
Temperature inside Earth increases at a rate of approximately 35 degrees celcius per kilometer. This is referred to as the Geothermal Gradient.

20. Earth is a Dynamic Planet
It changes slowly over millions of years (erosion of a mountain)
But it can also have dramatic quick changes (volcanic eruptions and earthquakes)

21. Hydrosphere
Biosphere
Geosphere
Atmosphere

22. Which layer do you think developed 1st? 2nd? 3rd?

23. Order of development Geosphere  hydrosphere  atmosphere biosphere
Hydrosphere and atmosphere formed from early “outgassing”, where molten material cooled and released dissolved gases into the atmosphere (N2, H2O vapor, CO2, Ar)

25. The earth is a complex set of interacting systems
Each sphere influences one another and effects our daily lives

26. The earth is a complex set of interacting systems
Ex. Water cycle
Ex. Volcanic eruption
How does each illustrate interactions among Earth’s spheres?

27. All 4 spheres?

28. All 4 Spheres

29. All 4 Spheres
Shoreline