1. The interior of the earth and it’s surface
Chapter 9 and 10
The interior of the earth
and it’s surface

2. The Interior of the Earth
We can’t go there
Use the shock waves an earthquake makes to investigate it.
Called seismic waves
Two types
S waves (sheer waves)
P waves (pressure waves)
Measured with a seismograph

3. Seismograph
Heavy object
Drum

4. Seismograph
As ground shakes
the base moves
but the weight stays still

7. Seismic waves Penetrate earth and return to surface.
Speed and direction change
S waves can’t go through liquids
P waves can, but they slow down.
As the waves go through the earth at 2900 km down, the S waves stop and the P waves slow down
At 5105 Km down the P waves speed up
What does this tell us?

8. The Earth’s Core The center of the earth Two layers Inner core
Iron and Nickel
5000º C
Pressure keeps it solid
Responsible for magnetic field?

9. The Earth’s Core The outer core Iron and Nickel 2200º C to 5000º C
Not as much pressure so it is liquid
How do they know
P waves are pressure waves
Will go through liquid
S waves are sheer waves
won’t go through liquids

10. S waves
Liquid

11. P waves

12. Total
Shadow
No waves

14. The Mantle Above the outer core 80% of the earth’s volume
Studied rocks from volcanoes
Have studied rocks from the ocean floor
Silicon, oxygen, iron, magnesium
Density increases with depth
Because there’s more iron
Measured by speed of the seismic waves

15. The Mantle Temperature increases with depth Has plasticity
What is plasticity?
A solid that can flow like a liquid
Silly putty
870º C -2200º C

16. The Moho the thin boundary layer between the mantle and the crust
32-64 km
Discovered by Andrija Mohorvičić
Found seismic waves changed speed at this level
Either different composition or density.

17. The crust Thin outer layer we live on
If the earth were the size of an apple, the crust would be thinner than the peel
8-32 km
Two kinds
Oceanic
Less than 10 km
all basalt- dense

18. The crust Continental crust Thicker- averages 32 km, up to 70 km
Top layer granite- less dense, on top of dense basalt
Earth’s crust also called lithosphere
Lithosphere broken into large plates (called tectonic plates)

19. 0 km
Crust
32 km
Moho
Mantle
2900 km
Outer Core
5150 km
Inner Core
6500km

20. Continent
Ocean
Granite
Basalt
Mantle

21. Chapter 10
How the crust moves

22. Crust Continental – Thicker Granite and basalt Oceanic Thinner
All Basalt
Stress- the pushes and pulls on the crust
causes changes in the rock
Shape
Volume
Compresses or expands
Deformation- breaking, tilting, and folding of of rocks

23. Stress
Three types
Compression- pushed together

24. Stress Three types Compression- pushed together
Moves land higher up and deeper

25. Stress
Tension
Pulled apart
Stretches like taffy
Thinner in the middle

26. Stress
Tension
Pulled apart
Stretches like taffy
Thinner in the middle

27. Stress Shearing- pushes in two opposite horizontal directions
Rocks are torn apart or bent

28. Stress Shearing- pushes in two opposite horizontal directions
Rocks are torn apart or bent

29. Stress changes Shape Volume Density Can cause cracks - fracture
Fracture along smooth surface is called a joint
Joints are parallel

30. Faults A break or crack where rocks move Where earthquakes happen
Hanging wall- above the fault
Foot wall- below the fault
Three types of fault
tension causes normal fault
Compression causes reverse fault and thrust fault

31. Normal fault Tension pulls apart Hanging wall moves down Hanging wall
Foot wall

32. Normal fault
Tension pulls apart
Hanging wall moves down

33. Reverse fault Compression pushes together the hanging wall up
Foot wall

34. Reverse fault
Compression pushes together
the hanging wall up

35. Thrust Fault Compression continues
The hanging wall is pushed over the foot wall
end up with layers of rock repeated
Older rock on top of younger rock

36. Thrust fault
Youngest Rock
Oldest Rock

37. Lateral Fault
Caused by shear stress
Blocks move sideways

38. Lateral Fault
Caused by shear stress
Blocks move sideways

39. Faulted Mountains and Valleys
A series of normal faults will cause mountains to be uplifted.
Called Fault-block mountains
Sierras
Valleys will also be formed
Called rift valleys
Death Valley

40. Fault Block Mountain

41. Fault Block Mountain

42. Rift valleys

43. Rift valleys

44. Folding Some times rock doesn’t break It forms folds- like wrinkles
Upward fold- anticline
Downward fold- syncline
Vary in size, from microscopic to mountain forming

45. Anticline
Syncline

46. Why Fold Why don’t they break Temperature- hot rock is easier to bend
Pressure- higher pressure more likely to fold
Type of rock- some are more brittle, some are more malleable
Gradual force bends, sudden force breaks

47. Plateau
Flat area made of layers of flat-topped rocks high above sea level
Can be formed like fault block mountains
Or by lava flows (lava plateau)
Colorado plateau- West of the Rocky mountains
formed Grand canyon
Rivers cut large plateau into several smaller ones

48. Domes Magma forms a bubble underneath the crust, without erupting
Half sphere surrounded by flat land
If worn into separate peaks they are called dome mountains

49. The Crust Floats On the mantle Because it is less dense
The floating crust pushes down
The crust pushes up.
Balance of forces called isostasy
More material floats lower

50. Isostasy
Crust
Mantle

51. Isostasy
Ice
Crust
Mantle

52. Isostasy
Ice
Crust
Mantle

53. Over time depression will rise back up.
Isostasy
Crust
Mantle
Over time depression will rise back up.

54. Isostasy
Sediments wash off
continents
Continental crust
Mantle

55. Isostasy
Sediments pile up
on ocean floor
Continental crust
Mantle

56. Isostasy
Pushes ocean
floor down
Continental crust
Mantle