Download Ch 7 study guide answers

Chapter 7 Study Guide KEY
Plate Tectonics
Directions: Please answer the following questions.
1. What kind of crust makes up tectonic plates?
Continental Crust (less dense) and Oceanic Crust (more dense)
2. What did Wegener call the one large landmass when all the continents were together?
Pangaea
3. Where does new oceanic lithosphere form (hint: it happens in the ocean)?
Mid-Ocean Ridge
4. What type of plate boundary does an earthquake happen at most often (pick only one boundary)?
Transform Boundary
5. What is the liquid layer of the Earth’s core called?
Outer Core
6. What layer of the Earth consists mainly of iron?
Core – (inner and outer) inner core has the most iron
7. List some evidence that proved continental drift did occur?
Seafloor Spreading
Magnetic Reversals
8. Earthquakes mainly are associated with what one boundary?
Transform Plate Boundaries
9. Draw and label all the layers and sub layers of the Earth.
See last page
10. What do the tectonic plates “float” on?
The Asthenosphere
11. What produces seismic waves?
Earthquakes
12. What’s another name for continental-oceanic collisions when the denser plate goes down into the
mantle?
Subduction
13. What type of boundary creates the Mid-Ocean ridge?
Divergent Plate Boundary
14. What type of fault is the San Andreas Fault in California?
Transform Plate Boundary
15. How do convergent boundaries move?
They Collide
16. How do divergent boundaries move?
They Separate
17. How do transform boundaries move?
Slip Past Each Other
18. Where does sea-floor spreading take place?
Mid-Ocean Ridge
19. How are volcanic mountains formed?
Magma pushing up through the crust
20. What is it called when Earth’s magnetic poles change places?
Magnetic Reversals
Constructed Answers – You have to write your answer in sentences on the test.
1. If crust is continually being added to the surface of the Earth, then why has the diameter not changed?
Crust is continually being added at a mid-ocean ridge where a divergent boundary is located. The
diameter of the Earth does not change because crust is being destroyed at a convergent boundary where
subduction occurs.
2. What is the difference between a convergent and divergent plate boundary?
At a convergent plate boundary plates collide or come together. At a divergent plate boundary plates
separate or move away from each other in opposite directions.
3. Please explain how magma moves in convection currents (be specific and detailed).
In a convection current, magma is heated at the bottom of the mantle from the core of the Earth. As the
magma is heated up, it becomes less dense and rises to the top of the mesosphere. The magma begins to
cool and the more dense cooler magma sinks down toward the core of the Earth. The cycle is the
continuous heating, rising, cooling, and sinking of magma.
4. Why did Alfred Wegner believe that all of the continents once had been joined together to form
Pangaea (give at least three examples of evidence)?
Wegener believed that the continents were once connected based on evidence.
 There was fossil evidence of the swimming reptile the mesosaurus found on different sides of
the Atlantic Ocean.
 There are similar types of rocks of the same age and structure found on different continents.
 There is evidence on similar climate conditions found on different continents.
5. How were the Himalayas and Appalachian Mountains similarly formed?
The Himalayas and Appalachian Mountains were formed at two continental plate collided at a
convergent plate boundary causing the continents to fold or squeezed together.
6. How does a mid-ocean ridge form, and where would you find the youngest and oldest rocks on the
seafloor (explain)?
A mid-ocean ridge is a mountain chain found on the ocean floor. It is formed at a divergent boundary
where plates are separating. The magma is pushing up through the plate boundary causing the plates
to move away from each other. The youngest rock is found at the mid-ocean ridge. The rock get older
as you move away from the mid ocean ridge.
7. What are subduction zones and at what type of boundary does it occur?
Subduction occurs at a convergent boundary where a continental plate collides with an oceanic plate
and the less dense continental plate sinks into the asthenosphere. .
8. Draw and label an interior view of the Earth. Make sure to label the following layers: Crust, Inner
Core, Mantel, Lithosphere, Outer Core, Asthenosphere, Mesosphere, and Convection Currents.
See the last page