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Objectives
 F.2.1.1. Explain how stress in the crust changes Earth’s
surface.
 F.2.1.2. Describe where faults are usually found and
why they form.
 F.2.1.3. Identify the land features that result from plate
movement.
Stress
Stress is a force that acts on rock to
change it’s shape or volume. The
energy is stored in the rock until
changes shape or breaks. This is
where earthquakes come from.
There Are 3 Types of Stress
Tension
Compression
Shearing
Types of Stress
Tension, compression and
shearing work over millions of
years to change the shape and
volume of Earth’s crustal rocks.
Tension
Tension pulls the crust apart
making it thinner in the middle.
Tension occurs where two
plates are moving apart. Can
you give me an example of a
location where tension is the
dominant stress?
Mid Atlantic Ridge
Compression
Compression squeezes
rock together until it folds
or breaks. Can you think
of places where
compression is the
dominant stress?
Plates Converge
Continental/Oceanic
Continental/Continental
Shearing
 Shearing pushes
rock in opposite
directions. Can you
think of a place
where shearing is
the dominant
stress?
San Andreas Fault
 The San Andreas
Fault lies along the
California coast.
The Pacific Plate is
pushing north at a
couple of inches a
year.
San Andreas Fault
Kinds of Faults
 Most faults occur along plate boundaries where the
forces of plate motions push or pull the crust so much
that the crust will break. The 3 types of faults are:
 Normal Fault
 Reverse Fault
 Strike Slip Fault
Normal Fault
 In a normal fault, the
hanging wall slides
down the foot wall.
What kind of stress is
acting on a normal
fault?
 Tension
Reverse Fault
 In a reverse fault, the
hanging wall pushes up
and sometimes over
the foot wall. What
kind of stress produces
a reverse fault?
 Compression
Strike-Slip Fault
 In a strike slip fault,
the rock slide past each
other in opposite
directions. What kind
of stress causes a strike
slip fault?
 Shearing
Changing Earth’s Surface
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.
Folding Earth’s Crust
Syncline
Anticline
A fold of
rock that
bends
downward to
form a valley.
A fold of
rock that
bends upward
to form a an
arch.
Syncline and Anticline
Fault Block
Mountains
When two normal faults
are parallel to each other,
a fault block mountain
will form as the rock
between the faults rises
upward and the faults slip
down.
The Colorado Plateau
Colorado Plateau
Plateau
A plateau is a large flat
area elevated by uplift to
high above sea level.
The Grand Canyon
 The Grand Canyon lies in the Colorado
Plateau and has been carved out of the plateau
over millions of years by the Colorado River.
Do you know what the process of a water
carving out rock is called?
 Erosion
The Grand Canyon