Download a) normal fault - cloudfront.net

WHOSE FAULT IS IT?
In this activity, you will build a model of the earth’s crust. Using this model, you can
demonstrate the action of the three types of faults we have discussed. A FAULT is a crack
within the earth’s crust. A fault should not be confused with a BOUNDARY, which is the edge
of an entire tectonic plate. A boundary goes all the way through the earth’s crust, from the
surface to the asthenosphere.
Most faults are vertical cracks in the earth’s crust, but they are not exactly straight up
and down. They are usually slanted in one direction. The wall below the fault, where you
would put your feet if it were a tunnel, is called the FOOT WALL. The wall above the crack,
where you might hang lights as you go down the tunnel, is known as the HANGING WALL.
Movement along boundaries is the main cause of earthquakes and volcanoes, but
movement along faults can also produce earthquakes (though NOT volcanoes).
Follow the instructions below and on back.
Answer any questions on a separate piece of paper.
A) NORMAL FAULT
Locate dots A and B on your model. Move the two pieces of the model so that A and B are
next to each other. This represents a NORMAL FAULT. In a normal fault, the hanging wall
moves down lower than the foot wall.
1) On your paper, make a sketch to show how rock layers X, Y, and Z look from the side,
AFTER you lined up letters A and B. Try to do the sketch in 3-D.
2) Which two letters on the side of the model represent the hanging wall?
3) What kind of stress caused this fault to occur?
4) What might happen to the river if it was moving from southwest to northeast?
5) What might happen to the river if it was moving from northeast to southwest?
B) REVERSE FAULT
Locate dots C and D on your model. Move the two pieces so that C and D are next to each
other. This represents a REVERSE FAULT. In a reverse fault, the hanging wall moves up
higher than the foot wall.
6) On your paper, make a sketch to show how rock layers X, Y, and Z look from the side,
AFTER you lined up letters C and D. Try to do the sketch in 3-D.
7) Which two letters on the side of the model represent the foot wall?
8) What kind of stress caused this fault to occur?
9) What will have to be done to make the road useable? To make the tracks useable?
C) STRIKE-SLIP FAULT
Locate dots E and F on your model. Move the two parts of the model so that E and F are next
to each other. This represents a STRIKE-SLIP FAULT. Notice that the hanging wall didn’t
move up higher or down lower than the foot wall.
10) On your paper, make a sketch to show how rock layers X, Y, and Z look from the side,
AFTER you lined up letters E and F. Try to do the sketch in 3-D.
11) Label the HANGING WALL and FOOT WALL.
12) What type of stress would cause this fault?
13) Describe how things have changed on the surface of the land. Be descriptive.
14) What might happen to the river if it was moving from southwest to northeast?
15) What will have to be done to make the road useable? To make the tracks useable?
D) FOLLOW-UP QUESTIONS: Answer the remainder of these questions on your paper.
16) Locate dots H and I on your model. Move the model so that H and I are next to each other
What kind of fault does this movement represent?
What kind of stress created this fault?
17) Locate dots J and K on the model. Move the model so that J and K are next to each other
What kind of fault does this movement represent?
What kind of stress created this fault?
18) Locate dots F and G on your model. Move the pieces until F and G are next to each other
What kind of fault does this movement represent?
What kind of stress created this fault?
The SCALE used to make you model is…
1 millimeter (mm) on model = 2 meters (m) of actual land.
19) What is the length (L) of the land represented by this model, in meters? (west to east)
20) What is the width (W) of the land represented by this model, in meters? (north to south)
21) Calculate the AREA (A) of the land represented by the model?
It is measured in square meters (m2)
Area = L x W
22) Using the same scale, determine how far the earth actually moved if dot F was moved
next to dot E on the model (in meters)