1. Introduction to Planet Earth
Let’s dig a hole to China!

2. Earth Stats The Earth's mass is about 5.98 x 1024 kg.
Earth is the densest planet in our Solar System (mass/volume).
Earth is made of several layers with different compositions and physical properties, like temperature, density, and the ability to flow.
MASS, DENSITY, AND ESCAPE VELOCITY The Earth's mass is about 5.98 x 1024 kg. The Earth has an average density of 5520 kg/m3 (water has a density of 1027 kg/m3). Earth is the densest planet in our Solar System. To escape the Earth's gravitational pull, an object must reach a velocity of 24,840 miles per hour (11,180 m/sec).

3. The Composition of the Earth
The Earth is made of many different and distinct layers. The deeper layers are composed of heavier materials; they are hotter, denser and under much greater pressure than the outer layers.

4. The Composition of the Earth
Crust
Thinnest layer (5-100 km)
Two types of crust
Continental
Like granite
Average 30 km
Oceanic
Like basalt
(Basalt is denser than granite!)
Average 5-8 km

5. The Composition of the Earth
Mantle
Extremely Thick! (2,900 km)
It is too far down to drill
How do we know what it is made of?
Scientists infer based on:
Pushed up rock
Ocean floor/molten rock
What is it like?
Like the mineral olivine
Large amounts of iron and magnesium
The Earth is made of many different and distinct layers. The deeper layers are composed of heavier materials; they are hotter, denser and under much greater pressure than the outer layers. Core: The Earth has a iron-nickel core that is about 2,100 miles in radius. The inner core may have a temperature up to about 13,000°F (7,200°C = 7,500 K), which is hotter than the surface of the Sun. The inner core (which has a radius of about 750 miles (1,228 km) is solid. The outer core is in a liquid state and is about 1,400 miles (2,260 km) thick.

6. The Composition of the Earth
Core
Pretty darn big. (6,856 km)
(Slightly bigger than Mars!)
33% mass of the Earth
Scientists think….
Made mostly of iron
Some nickel, sulfur, oxygen
What is the evidence?
The particular way seismic waves travel
Earth’s Magnetic field
The Earth is made of many different and distinct layers. The deeper layers are composed of heavier materials; they are hotter, denser and under much greater pressure than the outer layers. Core: The Earth has a iron-nickel core that is about 2,100 miles in radius. The inner core may have a temperature up to about 13,000°F (7,200°C = 7,500 K), which is hotter than the surface of the Sun. The inner core (which has a radius of about 750 miles (1,228 km) is solid. The outer core is in a liquid state and is about 1,400 miles (2,260 km) thick.

7. The Structure of the Earth
Lithosphere
Solid
Asthenosphere
Viscous Liquid
The Structure of the Earth
Outer Core
Liquid
Mesosphere
Solid
Core: The Earth has a iron-nickel core that is about 2,100 miles in radius. The inner core may have a temperature up to about 13,000°F (7,200°C = 7,500 K), which is hotter than the surface of the Sun. The inner core (which has a radius of about 750 miles (1,228 km) is solid. The outer core is in a liquid state and is about 1,400 miles (2,260 km) thick.
Core: The Earth has a iron-nickel core that is about 2,100 miles in radius. The inner core may have a temperature up to about 13,000°F (7,200°C = 7,500 K), which is hotter than the surface of the Sun. The inner core (which has a radius of about 750 miles (1,228 km) is solid. The outer core is in a liquid state and is about 1,400 miles (2,260 km) thick.
Inner Core
Solid

8. Lithosphere = ‘rock sphere’
Crust and upper rigid part of Mantle
Asthenosphere = ‘weak sphere’
Lower part of Mantle

9. How HOT is it?
Surface of Sun!
5,500°C
Sun Core
15,000,000°C

10. Convection Convection (heat) currents
carry heat from the hot inner mantle to the cooler outer mantle.
The mantle gets warmer with depth
top of the mantle is ~ 1,600° F (870° C)
bottom of the mantle is ~4,000-6,700° F (2,200-3,700° C)
The mantle contains most of the mass of the Earth

12. Let’s Make Models of the Earth!
Inner Core (yellow) diameter 2 cm (4)
Outer core (orange) diameter 6 cm (4)
Mesosphere (red) diameter 11cm (4)
Asthenosphere (brown) diameter 12cm (2)
Lithosphere (sand)
-after assembly roll edges of asthenosphere in glue and then sand (1.5mM thick)

13. How do scientists know what makes up the earth’s interior if we can’t actually dig a hole through the earth to see it directly?

14. 1.Direct evidence from rock samples.
and
2.Indirect evidence from seismic waves when we have an earthquake. (The speed of seismic waves and the path they take through the earth reveal the structure of the planet.)

15. Why does the earth have high temperatures in the center
Why does the earth have high temperatures in the center? Where does the heat come from?

16. The high temps. inside the earth are the result of heat left over from the formation of the planet. Also, radioactive substances inside the earth release energy.

17. What kind of rock makes up the oceanic crust?

18. A dark rock with a smooth texture.
Basalt
A dark rock with a smooth texture.

19. What kind of rock forms the continents?

20. A rock that is light in color and has a coarse texture.
Granite
A rock that is light in color and has a coarse texture.

21. 3 Types of Heat Transfer
1. Radiation--through space, no direct contact. Ex: Sunlight to earth, campfire
2. Conduction--between materials that are touching. Spoon gets hot as it sits in a pot of hot soup.
3. Convection--movement of fluids and currents in the fluids. Ex: boiling water

22. Convection Caused by: temperature differences density differences
gravity
Occur in the outer core (magnetism)and mantle (plate tectonics)

23. Alfred Wegener 1915
German man who proposed the Continental Drift Theory.
Pangaea--super continent “all lands”
Evidence:
land features
fossils
climate change

24. Sea-floor Spreading
The sea floor spreads apart along both sides of a mid-ocean ridge (forms a crack in the ocean floor) as new crust is added. As a result, the ocean floors move like conveyor belts, carrying the continents along with them. Molten material fills in the crack as it rises to the surface. As it cools, it forms a strip of rock in the center of the ridge.

25. Evidence of Sea-floor Spreading
Read pages 24 F-29 F
Rocks shaped like squeezed toothpaste
Magnetic Stripes
Drilling Samples

26. Subduction at Trenches
Where the oceanic crust bends downward and sinks back into the mantle
Pacific Ocean is shrinking!!
Subduction is occurring faster than new crust is being produced.

27. Plate Tectonics
The lithosphere is broken into separate sections called PLATES that move because of convection currents in the mantle.
This is the sea-floor spreading and continental drift theories wrapped into one.

28. Plate Boundaries--Faults
Divergent--where two plates move apart, at mid-ocean ridges where sea-floor spreading occurs.
Convergent--where two plates come together and collide. The density determines which sinks. Creates Mountain ranges.
Transform--slipping past each other. Earthquakes occur here.