1. Chapter 2 Earth’s Interior
Sylvia Marquez

2. Vocabulary Seismic waves Lithosphere Pressure Mesosphere Crust
Basalt
Granite
Mantle
Asthenosphere
Lithosphere
Mesosphere
Inner core
Outer core
Oceanic crust
Continental crust

3. How do geologists learn about earth’s interior?
Processes that affect Earth’s surface are often a result of what’s going on inside Earth. But what’s inside Earth? Geologists use two main types of evidence to learn about Earth’s interior: direct evidence from rock samples and indirect evidence from seismic waves.

4. Evidence from rock samples
Geologists have drilled holes as deep as kilometers into Earth. The drills bring up samples of rock that give them clues about Earth’s structure and conditions deep inside Earth, where the rocks formed. In addition, volcanoes sometimes blast rock to the surface from depths of more than 100 km. These rocks provide information about Earth’s interior.

5. Also, in laboratories, geologists have re- created conditions inside Earth to see how rock behaves. They use laser beams on pieces of rock while squeezing the rock with great force, to find out how elastic rocks are. They do this to show how rocks behave under great pressure.

6. Evidence from seismic waves
Geologists also use an indirect method. When earthquakes occur, they produce seismic waves. Geologists record the waves and study how they travel through Earth. The speed of seismic waves and the paths they take give geologists clues about the structure of the planet. The paths of these waves reveal areas inside Earth where the makeup or form of material changes. To better understand how this works, let’s see a video.

7. Let’s watch this video to learn more about seismic waves

8. Assess
Other than rock. What do you think you can find below the surface of Earth?
How did geologists gather information from the interior of our planet?
What direct evidence of Earth’s interior do geologists use?
What limitation do geologists have when studying Earth’s interior?
How did the behavior of the waves “show” the location of different layers on Earth’s interior?

9. features of earth’s crust, mantle, and core
The layers that make up Earth vary in thickness, composition (the elements that make them up), and pressure (the amount of force pressing on them).
Scientists know that Earth’s interior is made up by three main layers, and each one covers the layers beneath it, like the layers of an onion.

10. The three main layers are:
Crust-a layer of solid rock that includes both dry land and the ocean floor
Mantle-is made of rock that is very hot, but solid.
Core- made mostly of the metals iron and nickel, but it also has oxygen, sulfur, and silicon

11. Each layer has its own characteristics, some of them apply throughout all of Earth. For example, the deeper inside Earth, the greater the mass of the rock that is pressing down from above.
Pressure results from a force pressing on an area because of the weight of the rock above, pressure inside Earth increases its depth. The deeper down inside Earth, the greater the pressure.

12. The mass of rock that presses down from above affects the temperature inside Earth. The temperature inside earth increases as depth increases.
Beneath Earth’s surface, the surrounding rock is cool, but at 20 meters down, the rock starts to get warmer.
For every 40 meters of depth from that point, the temperature typically rises 1 Celsius degree

14. Crust The layer of soil where you step on is called crust
The crust is a layer of solid rock that includes both dry land and the ocean floor
The main elements in the crust are oxygen and silicon
It’s thinner than the layer that lies beneath it
In most places, the crust is between 5 and 40 km, thick

15. It is thickest under high mountains-where it can be as thick as 80 km
It is thickest under high mountains-where it can be as thick as 80 km.-and thinnest beneath the ocean
The crust beneath the ocean is called oceanic crust
Its overall composition is much like basalt, with small amounts of ocean sediment on top
The crust that forms continents is called continental crust, it contains many types of rocks
Unlike oceanic crust, its composition varies greatly, but it is mostly formed by granite

16. Composition of the crust

17. What percent of the crust is iron?
Which element makes up 2.6 percent of the crust?
In total, how much of Earth’s crust is made up of oxygen and silicon?
What is temperature?
What general statement can you make about the change in temperature through Earth’s interior?

18. What general statement can you make about the change in pressure inside Earth?
Why does temperature increase the deeper you go?
Which type of crust is thicker: continental or oceanic?
Is it possible for solid rock to flow?

19. Assess: create a table comparing the two types of crust by filling the information required
Oceanic Crust
Continental Crust
Typical rock:__________
Relative grain size:__________
Color:________
Thickness:__________
Forms:_________
Typical rock:_________
Relative grain size:_________
Color:_________
Thickness:_________
Forms:________

20. Mantle
About 40 km. beneath dry land, the rock in Earth’s interior changes. The rock contains more magnesium and iron than rock above it. The rock below the boundary is the solid material of the mantle, a layer of hot rock. The mantle is made of rock that is very hot, but it’s still solid. Scientists divide the mantle into layers based on the physical characteristics of each layer. Overall, the mantle is nearly 3,000 km. thick.

21. Layers of the mantle Lithosphere Asthenosphere Mesosphere
*Below the crust
*Brittle rock, like the crust
*Uppermost layer
*Strong, hard, rigid
*Averages about 100 km. thick
*Below the lithosphere
*Hotter and under increasing pressure
*Less rigid than rocks above
*Over thousands of years this part can bend like a metal spoon
*If you kicked it, it will stub your toe
*Softer than the lithosphere
*Beneath the asthenosphere
*It’s hot but more rigid because of high pressure
*It includes a region called the transition zone, which lies beneath the asthenosphere
*It includes the lower mantle, which extends down to Earth’s core

22. Mantle

23. Core
Below the mantle lies Earth’s core. It is made mostly of the metals iron and nickel. It consists of two parts-a liquid outer core and a solid inner core. The outer core is 2,258 km. thick. The inner core is a solid ball. Its radius is 1,222 km. The total radius of the core is 3,480 km. The core occupies the center of the planet.

24. Outer Core
Inner Core
A layer of molten metal surrounding the inner core
Despite enormous pressure, it’s liquid
It’s made of iron and nickel, but it also contains oxygen, sulfur, and silicon
A dense ball of solid metal
Extreme pressure squeezes the atoms of iron and nickel so much that they cannot spread out to become liquid
It’s made of iron and nickel, but it also contains oxygen, sulfur, and silicon

25. The Core and earth’s magnetic field
Scientists think that movement s in the liquid outer core create Earth’s magnetic field.
Because Earth’s magnetic field, the planet acts like a giant bar magnet .
Earth’s magnetic field affects the whole planet

26. Earth’s magnetic field
If you place a magnet on a piece of paper and sprinkle iron filings on the paper, the iron filings will line up with the bar’s magnetic field
If you could surround Earth with iron filings, they would form a similar pattern
Let’s see:

27. When you use a compass, the compass needle aligns with the lines force in Earth’s magnetic field
These lines meet at Earth’s magnetic poles
The needle points to Earth’s magnetic north pole which is not the same location as Earth’s geographic North Pole

28. More about magnetism

29. Video: Layers of the earth

30. Questions Why is the asthenosphere different from the lithosphere?
How does the inner core differ from the outer core?
Why do you think geologists consider the inner core and the outer core as part of the same layer?
How does the thickness of continental crust and oceanic crust compare?
Which of earth’s layer is the thickest?
Which is the thinnest?

31. Venn diagram
Inner Core
Outer Core
Both

32. Summarize TOTAL Crust 5-80 km. Granite/basalt solid Mantle
Thickness/Radius
Composition
Solid/Liquid
Crust
5-80 km.
Granite/basalt
solid
Mantle
2,811-2,886 km.
Hot rock
Outer Core
2,258 km.
Iron/nickel
liquid
Inner Core
1,222 km.
TOTAL
6,446 km.

33. Ready for the test!