Download The Theory of Plate Tectonics On a separate sheet of paper

The Theory of Plate Tectonics
On a separate sheet of paper, summarize the changes to Earth’s surface that occur as
a result of plate movements.
91C
Name
Date
Class
The Theory of Plate Tectonics
Understanding Main Ideas
Label each diagram by writing the type of plate boundary it shows.
1.
2.
3.
Answer the following questions on a separate sheet of paper.
4. Describe what happens when (a) two plates carrying oceanic crust
collide, (b) two plates carrying continental crust collide, and (c) a
plate carrying oceanic crust collides with a plate carrying continental
crust.
5. Explain what force caused the movement of the continents from one
supercontinent to their present positions.
Building Vocabulary
Fill in the blank to complete each statement.
6. At a(n)
, plates come together.
7. Breaks in Earth’s crust where rocks have slipped past each other are
called
.
8. The lithosphere is broken into separate sections called
9. A(n)
a divergent boundary.
.
is a deep valley on land that forms along
10. The geological theory that states that pieces of Earth’s crust are in constant,
slow motion is called
.
11. At a(n)
each other.
, plates slip past
12. Plates move apart along a(n)
.
91D
Name
Date
Class
The Theory of Plate Tectonics
Use the graph to answer the questions that follow on a separate sheet of paper.
Magnetic Reversals Through the Ages
How often does Earth’s magnetic field reverse itself? The graph below shows the record geologists have
put together for the last 65 million years. As you might know, the last of the dinosaurs died about 65
million years ago. So you can think of this graph as the record of Earth’s reversals since the dinosaurs
became extinct.
In this graph, each dark band represents a “normal” magnetic field, as it is today. Each light band
represents a reversed magnetic field.
1. Was Earth’s magnetic field “normal” or reversed 65 million years ago?
2. About how long ago was the last time Earth’s magnetic field
reversed?
3. Can you see any pattern in how often Earth’s magnetic field reverses?
Give reasons for your answer.
4. How would this history of reversals show itself on the ocean floor?
5. From this graph, when would you predict the next reversal would
occur? Give reasons for your answer.
91E
Name
Date
Class
The Theory of Plate Tectonics
If the statement is true, write true. If the statement is false, change the underlined word
or words to make the statement true.
1.
Earth’s plates meet at boundaries.
2.
Breaks in the crust called faults form where plates meet.
3.
Plates slide past each other at convergent boundaries.
4.
A(n) rift valley forms where plates diverge on land.
5.
Ocean currents drive Earth’s plates.
6.
Most transform boundaries where plates move apart occur
along the mid-ocean ridges.
Write the letter of the correct answer on the line at the left.
7.
Which theory describes the motion
of and force driving Earth’s plates?
A first law of motion
B third law of motion
C continental drift
D plate tectonics
9.
The San Andreas fault is an example
of which kind of boundary?
A transform
B divergent
C oceanic
D convergent
8.
What is the motion of Earth’s plates
like?
A fast and in stages
B slow and in stages
C fast and constant
D slow and constant
10.
Which feature forms at convergent
boundaries?
A mountain range
B trench
C rift valley
D mid-ocean ridge