Key Questions What happens to rocks when they are placed under
the large forces created by plate movements?
Slide 3
Types of Stress (page 163) Key Concept: Tension, compression,
and shearing work over millions of years to change the shape and
volume of rock.
Slide 4
You should be able to Explain how stress in the crust changes
the earths surface. Describe where faults are usually found and why
they form.
Slide 5
When Earths plates move, rocks are pushed and pulled. The
pushing and pulling forces cause: stress.
Slide 6
Stress adds energy to rocks. Rocks keep storing the energy
until they cannot stand any more stress. Then the rocks break or
change shape.
Slide 7
Tension is stress that pulls and stretches rocks. Tension makes
rocks thinner in the middle. Tension happens when two plates move
apart.
Slide 8
Compression is stress that squeezes rocks. Compression makes
rocks fold or break. Compression happens when two plates push
together.
Slide 9
Shearing is stress that pushes rocks in opposite directions.
Shearing makes rocks break, slip apart, or change shape. Shearing
happens when two plates slip past each other in opposite
directions.
Slide 10
Answer the following questions. ? ? ? ? ? ? ? ? ? ? ? ? ?
Slide 11
Circle the letter of the choice that describes how stress
affects rocks. a. Stress adds energy to rocks. b. Stress uses up
the energy in rocks. c. Stress squeezes energy out of rocks.
Slide 12
Pushes and pulls on rocks cause Stress that makes rocks fold or
break is called stress compression
Slide 13
Stress that stretches rocks is called Stress that makes rocks
break, slip apart, or change shape is called tension shearing
Slide 14
compression tension shearing
Slide 15
Kinds of Faults (pages 164165)
Slide 16
Key Concept: Most faults occur along plate boundaries, where
the forces of plate motion push or pull the crust so much that the
crust breaks.
Slide 17
Students will be able to Describe where faults are usually
found and why they form.
Slide 18
There are three main types of faults: normal faults reverse
faults strike-slip faults
Slide 19
A fault is a break in Earths crust where rocks are under
stress.
Slide 20
In many faults, the fault line is slanted. So the block of rock
on one side of the fault is above the block of rock on the other
side of the fault.
Slide 21
The top block is called the hanging wall. The bottom block is
called the footwall.
Slide 22
There are three different types of faults: normal faults
reverse faults strike-slip faults Each type is caused by a
different kind of stress on rocks.
Slide 23
A normal fault happens when tension pulls rocks apart. In a
normal fault, the hanging wall slips down and becomes lower than
the footwall.
Slide 24
A reverse fault happens when compression pushes rocks together.
In a reverse fault, the hanging wall slides up and becomes higher
than the footwall.
Slide 25
A strike-slip fault happens when shearing pushes rocks in
opposite directions. In a strike-slip fault, two blocks of rock
move past each other, but neither block moves up or down.
Slide 26
Answer the following questions ? ? ? ? ? ? ? ? ? ?
Slide 27
Circle the letter of the choice that explains what causes a
fault. a. Stress increases on rocks until they move. b. Energy
slowly drains away from rocks. c. Rocks heat up and melt.
Slide 28
tension Reverse fault Strike-slip fault
Slide 29
c. Reverse fault Normal fault Strike-slip fault
Slide 30
Changing Earths Surface (pages 166168)
Slide 31
Key Concept: Over millions of years, the forces of plate
movement can change a flat plain into landforms such as anticlines
and synclines, folded mountains, fault-block mountains, and
plateaus.
Slide 32
Students will be able to Identify the land features that result
from plate movement.
Slide 33
Stresses in Earths crust cause the surface to change. Different
stresses cause different changes.
Slide 34
Compression causes folding. Folding is like a rug getting
wrinkled up when it is pushed across the floor.
Slide 35
Folds that bend upward into ridges are called anticlines. Folds
that bend downward into valleys are called synclines.
Slide 36
Tension causes stretching. When crust stretches, many normal
faults form.
Slide 37
Sometimes a block of rock moves upward between two normal
faults. The block forms a mountain called a fault-block
mountain.
Slide 38
Stresses in the crust can also form plateaus. A plateau is a
large area of flat land that has been lifted up above sea
level.
Slide 39
Answer the following questions. ? ? ? ? ? ? ? ? ? ?
Slide 40
Circle the letter of the sentence that describes how a
fault-block mountain forms. a. A block of rock moves upward between
two normal faults. b. The crust becomes wrinkled like a rug. c.
Rocks are pushed together by compression.
Slide 41
Is the following sentence true or false? A plateau forms when
flat land is pushed up above sea level. TRUE
