1. The Theory of Plate Tectonics
Chapter 1, Section 5

2. What is J. Tuzo Wilson responsible for doing?
He proposed that the lithosphere is broken into separate sections called plates.
The plates fit closely together along cracks in the lithosphere
He combined sea-floor spreading, the plates and the ideas behind continental drift to create the theory of Plate Tectonics.

3. How is Plate Tectonics DIFFERENT from Continental Drift?
Plates vs Continents moving
Ability to explain the movement (convection currents in the mantle)

4. How is Plate Tectonics SIMILAR from Continental Drift?
Explained that the continents moved (All of the continental drift information)

5. What do most geologists believe causes the plates to move?
Convection currents in the mantle (friction of the molten material plus the force of gravity)

6. Continental & Oceanic
Oceanic
North American
Pacific
South American
Nazca
Eurasian
Caribbean
African
Philippines (purple)
Antarctic
Scotia (blue)
Indo-Australian
Cocoas (pink)
Arabian (purple)
Juan de Fuca (yellow)

7. Transform Boundaries
Plates slide past each other in opposite directions
North American Plate and the Pacific Plate (where California is being ripped in two parts)

8. Divergent Boundaries
The plates slide away from each other in opposite directions
Two Oceanic Plates Diverge… N. American & Eurasian; S. American & African; etc.
Landforms…. Mid-ocean ridge and the rift valley
Two Continental Diverge… N. American & Eurasian (Iceland); Africa (Great Rift Valley)
Landforms… rift valley

9. Convergent Boundaries
The plates push towards each other
Two Oceanic Plates Converge… Pacific & Philippines (Marinas); Pacific & N. American (Aleutian)
Landforms…. Trench, a line of volcanic islands (mountians on the ocean floor)

10. Convergent Boundaries (continued)
Two Continental Converge… Eurasian & Indo-Australian (Himalayas)
Landforms… mountains

11. What do you need to know to predict where the continents will be in 50 million years?
The types of boundaries on each side of the plate.
Which direction the plate is moving.
The speed the plate is moving.

12. What is a rift valley? How are rift valleys formed?
The steep sided valley found where two plates diverge.
This can be found where continental plates are ripping apart (Africa’s Great Rift Valley and in Iceland)
It can also be found in the middle of the Mid-Ocean Ridge.
As the plates diverge, molten material rises and create new land. This creates the valley floor.

13. What types of plate movement occur at plate boundaries?
Transform
Slide past each other in opposite directions
Convergent
Push towards each other
Divergent
Pull away from each other

14. Section Review
1. What is the theory of plate tectonics? The theory of plate tectonic explains the formation, movement and subduction of Earth’s plates. 2. What are the different types of boundaries? Transform, divergent and convergent 3. What major event in Earth’s history began about 225 million years ago? The supercontinent Pangaea began to break apart. 4. Find the divergent boundary the runs through Africa. What can eventually happen along this boundary? If the rift valley continues to grow, it could someday split the eastern part of Africa away from the rest of the continent eventually forming a new ocean.