1. Part I of Plate Tectonics

2. The origins of plate tectonics
The idea that the Earth’s surface might be moving is not new.
As early as the 17th century scientists noticed the puzzle fit of many land masses on Earth.

3. In 1912 a German scientist named Alfred Wegener proposed the Continental Drift Hypothesis as a means of explaining this phenomenon.

4. What is continental drift?
Hypothesis that proposed that the continents have moved from one location to another over time.
At one time, there was a single, supercontinent, called Pangaea.

5. Pangaea 225 MYA (Permian Period)

6. Continental Drift in Action: The Break-up of Pangea
25 MY
▪ Formation of Gondwanaland and Laurasia

7. Continental Drift in Action: The Break-up of Pangea
135 mya
70 MY
Breakup of Pangea

8. Continental Drift in Action: The Break-up of Pangea
65 MY
Present Day!
Death of Dinosaurs

9. What evidence did Wegener use to support his hypothesis of continental drift?
Puzzle fit of Africa & South America
2. Fossil evidence
3. Distinctive mountain and rock formations
All Wegener’s support was based on observations!!
4. Climate change evidence

10. Puzzle fit of Africa & South America

11. 2. Fossil Evidence

12. 2. Fossil remains of Mesosaurus

13. 3. Distinctive rock Formations
Age of rocks are the same on several continents.

14. 3. Mountain Ranges Correlate
Mountain ranges terminate at same position across the world.

15. 4. Paleoclimate change evidence
Glacial Deposits at Equator
Coral Reefs in Antartica

16. Based on this evidence, do you think that Wegener’s peers supported his continental drift theory? The theory was rejected because it could not explain HOW the continents had moved. NO

17. The origins of plate tectonics
In the 1950’s & 1960’s, discoveries led other scientists to re-examine Wegener’s continental drift theory.
These scientists found that while the continents did not move the way Wegener suggested, something was moving

18. What is the Plate Tectonic Theory?
They proposed the theory of plate tectonics!
What is the Plate Tectonic Theory?
The theory that the lithosphere is made of plates that move on the asthenosphere and interact with one another.

20. Egg analogy!

22. Add the following notes to your foldable

23. The Crust Thinnest Layer-Average 30 km
Composed of Oxygen and Silcon based rocks
Solid
oceanic crust
Very dense
continental crust
lighter

24. Largest layer of the Earth –average 2900 km
Composed of silicate rocks rich in magnesium and iron.
Molten rock with convection currents constantly moving.
Upper mantle and lower crust make the ASTHENOSPHERE.

25. Convection Currents
The middle mantle "flows" because of convection currents.
Convection currents
very hot material at the deepest part of the mantle rising,
then cooling and sinking again
repeating this cycle over and over.

26. The Outer Core Average 2300 km thick
composed of the melted metals of nickel and iron.
very hot liquid

27. The Inner Core 1,216 km Thick Made of nickel and iron
high temperatures and pressures
Solid!

28. Evidence that supports plate tectonics
Seafloor spreading
2. Earth’s Paleomagnetic Record
3. Location of Earthquakes & Volcanic Hotspots

29. 1. Sea Floor Spreading
The process by which new ocean floor is formed by lava erupting from a crack, pushing the existing floor outward.
Youngest rock is near the center.
Atlantic Ocean is getting larger.

30. 2. Earth’s Magnet Field
Metals in Earth’s liquid outer core are always moving (convection currents)
AND
Earth is always moving.
When metal moves electric currents are created this produced a magnetic field.

31. Paleomagnetic Record Lava and sediments contain iron-bearing minerals
When they cool or are deposited on the iron lines up with the Earth’s magnetic field.
If the Earth’s magnetic field switches then the iron lines up differently.
This is known as 'paleomagnetism'.

32. Paleomagnetic Record

33. The magnitism moves out on each side like a mirror.
The youngest oceanic crust is at the ridge crest, and the oldest oceanic crust is at the continental margins.
The magnitism moves out on each side like a mirror.
Youngest
Oldest

34. Practice Question!

35. 3. Locations of Earthquakes and Volcanoes
Earthquakes and volcanoes do not occur randomly throughout the world. They occur primarily in concentrated belts, near plate margins!

36. 3. Locations of Earthquakes and Volcanoes

37. The crust! Crust is divided into two groups.
Oceanic- underwater, dense crust
Continental- land, lighter
Plate boundaries are where lithospheric plates meet. What happens at the boundary depends on the type of crust and the direction of the movement.

38. Plate Boundary Notes
Add to your table of contents: Plate Boundary Notes / 2.1.1
Turn to that page and divide the paper into thirds.
Use chapter 17.3 to label each section with the three types of plate boundaries.
Draw a picture of each (convergent should have at least two drawings). Make sure they are labeled.
Leave space to write notes tomorrow.

39. The major plates of Earth

41. Divergent (apart) Boundary
Continental-Continental
Rift Valley

42. Divergent boundary of two continental plates. Creates a rift valley.
Example: East African Rift

44. Divergent (apart) Boundary
Continental-Continental
Rift Valley
Oceanic-Oceanic
Mid-Ocean Ridge

45. Oceanic - Oceanic Divergent boundary
creates a mid-ocean ridge
creates new land

46. Iceland
Mid-Atlantic Ridge

47. Convergent (together) Boundary
Oceanic-Continental
Volcanic mountain range and trench
Slab-Pull model

48. Convergent boundary of an oceanic plate and a continental plate
Convergent boundary of an oceanic plate and a continental plate. Forms a volcanic mountain range and a trench.
Examples: Cascades or Andes Mts

50. Convergent (together) Boundary
Oceanic-Continental
Volcanic mountain range and trench
Slab-Pull model
Oceanic-Oceanic
Trench and Island Arcs

51. Convergent boundary of two oceanic plates
Convergent boundary of two oceanic plates. Creates an island arc and a trench.
Example: Japan

53. Slab- Pull .

54. Convergent (together) Boundary
Oceanic-Continental
Volcanic Mountain Range and Trench
Slab-Pull Model
Oceanic-Oceanic
Trench and Island Arcs
Continental-Continental
Mountain Range

55. Convergent boundary of two continental plates
Convergent boundary of two continental plates. Forms a folded mountain range.
Examples: Himalayas, Alps, Appalachian

56. Transform (sliding) Boundary
Two plates sliding past each other.
Forms a fault
Strike-Slip

57. Example: San Andreas Fault in California

59. How fast does all of this happen??????
SLOWLY
Approximately 5 centimeters per year

60. Practice Questions
Places where plates move apart are called _____________ boundaries.
When continental plates diverge a ___________ is formed.
When two oceanic plates converge what is created? _________________
The Appalachians formed mainly from continental plate collisions and therefore are a __________ mountain range.
The force moving the plates is ____________ .

61. Tectonic Plate Mapping / 2.1.1
Answer the Pre-Lab questions #1-5 and 13, 14 on the back of your map or in your notebook on a new page. Use a textbook if needed.
(15 minutes)
Label the map AS A CLASS to set up for our activity tomorrow.
Make sure your name is on your map and turn it in.

62. Hot Spots / 2.1.1
Turn to page 486 in the textbook. Read the section on Hot Spots. Answer the following:
What is a hot spot?
What US state was formed by a hot spot?
Based on the age of the oldest island in the Hawaiian island chain, approximately how old is the hot spot that formed Hawaii?

63. Hot Spots / 2.1.1
Hot spots are areas of volcanic activity in the middle of lithospheric plates.
Lava at hot spots usually flows smoothly over the surface.
Hot spots remain in the same location even though the lithospheric plate above it moves.
The most famous example of hot spot volcanism is ____________________.

65. Hot Spot Activity Complete the activity as a class.
Answer Questions #1-6 on the same page in your notebook.

66. Test Remediation Test Corrections Boundaries diagram Seafloor diagram
#, Letter, Explanation
Explanation cannot be rewriting the questions. Must be definitions, diagrams, examples or descriptions
Boundaries diagram
Seafloor diagram