1. “Window” to the Earth’s Interior
Formation of the Earth
“Window” to the Earth’s Interior

2. Read:
Excerpts from the Bryson article
Respond to the prompts

3. Warm up…
Use the pieces you have from your envelope to construct a square. Work by yourself and keep your eyes on your own square!

4. now…
Use the pieces you have from your envelope AND the extra piece I have given you to construct a square. Work by yourself and keep your eyes on your own square!

5. Which looks like Early Earth during it’s formation?B

7. How did the
Earth form?

9. ?How did Early Earth Form?
Homogeneous collection of small solid particles
Heat
Generated by “friction” causing the interior to become
molten
Dense material moved to the center; less dense to the edges
Materials that hit the Earth caused it to grow
As Earth began to COOL Radioactive elements moved out and heat was released

10. Geologic history began when solid rock formed.
over 3.8 billion years ago.
No rocks from that time exist today.
Why?

11. Inside the Earth Earth’s layers  Divided 2 different ways:
Based on composition
Based on physical properties

12. Modern Earth Three layers based on composition
Crust - Outermost layer - solid
Mantle - Below crust -liquid
Core - Center layer - solid/liquid
Layers vary in types of rock, density,
temperature, state of matter, and thickness

13. Read:
Excerpts from the Bryson article
Respond to the prompts

15. Composition of the Earth
Densest layers are in the core because denser objects always sink due to gravity, while less dense objects float to the surface.

16. Crust Continental Crust Oceanic Crust
Often composed of granite
mostly Al, Si, O, Ca, Na, K
thick (32 km)
Oceanic crust
Usually composed of basalt
mostly Si, O, Fe, Mg
thin (8 km)
Why does oceanic crust sit lower than continental crust?
- Basalt is more dense than rocks in continental crust.

17. The Mantle
A. Between the core and crust
B. Most of the Earth’s mass is in the mantle (thickness = 2900 km or 1800 miles)
C. Made of Si, O, Fe & Mg - Contains more Mg, which is denser than Al in the crust
D. Temperature = 870oC – 2200oC (1600oF – 4000oF)
The top layers of the mantle are hot enough to be plastic or semi-liquid, which allows it to…
FLOW
(10,000 times slower than the hour hand on a clock!)

18. There are places in the ocean where the mantle pushes through to form new rock along the ocean floor.
As a result, the ocean floor has a similar composition to the mantle.

19. The Core Makes up 1/3 of the Earth’s mass
Made mainly of iron and nickel (the denser elements)
Almost no silicon, oxygen, and aluminum

20. Outer Core Inner Core Solid Fe & Ni Temperature = 5000oC
Molten (liquid) Fe & Ni – produces Earth’s magnetic field
Surrounds Inner Core
Temperature = C
Less pressure than inner core
Inner Core
Solid Fe & Ni
Temperature = 5000oC
Extreme pressure
Why do you think part of the core is liquid, when the inner core is solid?
The intense pressure at the center of the Earth squeezes it into a solid!

21. Discovering Earth’s Layers
Oldham 1906
Mohorovičić 1909
Lehmann 1936
Oldham: 1897 Assam 8.1 EQ; 3 distinct waves; change in speed means change in substance-Earth has a core
Mohorovicic-seismograms from shallow eq; discontinuity between crust and mantle; some waves were straight but others bent; a transition zone
Lehmann-p waves were recorded traveling through core; Lehmann discontinuity-bw the cores-solid inner and liquid outer

22. Now… Observe the diagram of the Earth
Follow the directions and add the layers with regards to physical and structural composition
Label according to the directions

23. Physical Structure of the Earth
Five layers based on physical properties: 1) 2) 3) 4) 5)
Lithosphere
Asthenosphere
Mesosphere
Outer core
Inner core

24. 2 parts: rocky crust and rigid, outermost mantle
Litho- = “rock”
Lithosphere
Asthenosphere 
Mesosphere
Plastic (flowing) upper mantle directly beneath the lithosphere
Astheno- = “weak”
Dense, hard lower layers of the mantle
Meso- = “middle”

25. Tectonic Plates

26. Tectonic Plates
Pieces of the lithosphere that move around, floating on top of the denser asthenosphere
Each plate fits together with the plates around it.
There are 10 or so major plates, but around 50 or more total, including all of the smaller ones.

27. Oceanic and Continental Crust
The South American plate is a single plate containing both continental and oceanic crust. It is surrounded by several other oceanic plates.

28. Ice Cubes in a Punch Bowl
Both oceanic and continental plates float on top of the asthenosphere, like ice cubes floating in water, because of their…
Lower density
Just like ice cubes, the plates can move around and often bump into each other.
Some of the plate sits below the level of the asthenosphere, just like ice displacing water.
The thicker continental crust displaces more of the asthenosphere than does oceanic crust.

29. Mapping the Earth’s Interior
During earthquakes, seismic waves (vibrations) are sent in all directions, through the earth.
They reach different places at different times because of the ways the waves…
BEND and CHANGE SPEED
as they pass through the internal layers.

30. Reflect: How are the five layers divided?
2. Name the five layers and describe a characteristic of each.
3. How do we know the physical state of the layers if we have never traveled to them?

31. Crust
Upper Mantle
Lower Mantle
Inner Core
Outer Core

32. Reflect: How are the 3 layers divided?
Where are less dense materials located?
Do the layers follow the laws of density?
Do before you leave:
Write a mnemonic device or a sentence to remember the composition of each layer?