1. Chapter 10
Plate Tectonics

2. 1. Name and describe four pieces of evidence that supports Wegener’s Theory of Continental Drift.
Continents fit together like a jigsaw puzzle
Matching fossils are found on the shores of different continents separated by 1,000s of miles of ocean

3. 1. Name and describe four pieces of evidence that supports Wegener’s Theory of Continental Drift.
Fossils of tropical animals and plants are found at the poles, where they would not have been able to survive
Rock deposits from shores of different continents match

4. 2. How did Scientists map the ocean floor in detail in the 1940’s and 1950’s?
Before WWI, The ocean floor was mapped by dropping a rock on a string and measuring how far until it landed.
During WWI, scientists began using Sonar (sound waves)

5. 3. What did researchers discover on the floor of all the earth’s oceans?
Researchers discovered several long underwater mountain ranges.

6. 4. Describe how seafloor spreading works and give evidence that supports the theory.
Convection currents in the Earth’s mantle and core rise up and spread plates apart.

7. 4. Describe how seafloor spreading works and give evidence that supports the theory.
Evidence to support theory:
oceanic crust is younger as it gets closer to mid-ocean ridge
rock making up the ocean floor is much younger than the continents
iron in ocean crust reverses polarity as the magnetic pole switched. This left identical bands on either side of mid-ocean ridge.

8. 5. Describe the Theory of Plate Tectonics.
The crust is broken up into huge, thick plates that drift atop the soft, underlying mantle.
Plates move both horizontally and vertically
Over long periods of time, the plates also change in size as they are added to, crushed together, or pushed back into the Earth's mantle.

9. 6. Describe a divergent boundary and name the features that form at that type of boundary.
Plates pull apart at a divergent boundary.

10. 6. Describe a divergent boundary and name the features that form at that type of boundary.
A volcanic mountain chain forms in the ocean
A Rift Valley Forms on Land

11. 7. Describe a convergent boundary and name the features that form at that type of boundary.
Plates come together at a convergent boundary.

12. 7. Describe a convergent boundary and name the features that form at that type of boundary.
Continental to Oceanic – Volcanic Mountain Chain Forms
Oceanic to Oceanic –
Island Arc Forms
Continental to Continental – Mountain Chain Forms

13. 8. Describe a transform boundary and name the features that form at that type of boundary.
Plates slide past each other at a transform boundary.

14. 9. What is the current theory of how the plates move?
intense heat in the Earth’s core causes molten rock (magma) in the mantle layer to rise
magma moves in a pattern called a convection cell
warm magma rises, cools, and eventually sinks down
as cooled material sinks down, it is warmed and rises again.

15. 10. What is a subduction zone?
A place at a convergent boundary where one plate goes underneath the less dense plate and returns to the mantle