1. EARTH’S MOVING SURFACE
CHAPTER 4 LESSON 1
EARTH’S MOVING SURFACE

2. 4.1 INFORMATION

5. PLATE TECTONICS
1 - Earth’s surface is broken into large, rigid pieces

6. PLATE TECTONICS
2 -The plates move with respect to each other

7. TECTONIC PLATES
The pieces of Earth’s surface that move over Earth’s surface very slowly.

8. TECTONIC PLATES

9. TECTONIC PLATES
Earth has 15 large tectonic plates, plus many smaller plates.

10. TECTONIC PLATES
The motion of tectonic plates forms volcanoes and mountains and causes earthquakes.

12. CRUST
Earth’s outermost layer

13. OCEANIC CRUST
Crust under the oceans.

14. CONTINENTAL CRUST
Crust under the continents.

15. LITHOSPHERE
The crust and the uppermost part of the mantle

16. LITHOSPHERE

17. ASTHENOSPHERE
The partially melted portion of the mantle below the lithosphere

18. ASTENOSPHERE
The asthenosphere can bend more easily than the lithosphere because it is hotter than the lithosphere.

19. B. PLATE BOUNDARIES

20. RELATIVE MOTION
Scientists describe the movement of a tectonic plate as relative motion

21. RELATIVE MOTION
How it moves in relation to another plate.

22. RELATIVE MOTION
The type of boundary between plates depends on the relative motion of the plates.

23. DIVERGENT BOUNDARY
where two plates move away from each other.

24. DIVERGENT BOUNDARY
As plates move apart, new crust forms between them.

25. DIVERGENT BOUNDARY

26. DIVERGENT BOUNDARY

27. CONVERGENT BOUNDARY
where two plates move toward each other.

28. CONVERGENT BOUNDARY

29. CONVERGENT BOUNDARY

30. CONVERGENT BOUNDARY
One plate can sometimes move under another plate.

31. SUBDUCTION
when one tectonic plate moves under another tectonic plate

32. TRANSFORM BOUNDARY
where two plates slide past each other.

33. 3 TYPES OF BOUNDARIES

34. PLATE MOVEMENT
Tectonic plates move so slowly that geologists could not measure their movement until the 20th century.

35. PLATE MOVEMENT
New technology has determined that North America and Europe are separating from each other at an average rate of just 2.5 cm/y.

37. GPS
The network of satellites that can be used to accurately measure the position of any point on Earth’s surface.

38. GPS
Scientists can measure the speed and direction of plate movement by tracking

39. GPS
About 200 million years ago, North America and Europe were part of a large continent called Pangaea

40. GPS
when the plates moved apart, the Atlantic Ocean formed between the continents.

41. WHY PLATES MOVE

42. DENSITY
The amount of matter per unit of volume

43. DENSITY Density = mass / volume
How heavy it is divided by how much space it takes up

44. DENSITY
When a fluid is heated, its molecules spread out and it becomes less dense.

45. DENSITY
When fluids heat unevenly, the warmer, less- dense fluid rises, and the cooler, denser fluid sinks.

46. CONVECTION
the circulation within fluids caused by differences in density and thermal energy.

47. CONVECTION
Convection in the mantle can drag plates over Earth’s surface.

48. CONVECTION

49. SUBDUCTION
Plates can also move as a result of subduction.

50. SUBDUCTION
When two plates collide, one can subduct or sink into the hotter, less-dense mantle.

51. SUBDUCTION
The sinking part of a plate pulls the rest of the plate along.