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Chapter 4 Lesson 1:
Stress: Force that changes the rocks shape and volume.
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3 Different types of stress:
Tension: Pulls rock apart and thins the middle. EX) Rubber band or
bubble gum
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Compression: One plate pushes against another plate until it folds
or breaks. EX) Crash or collide.
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Shearing: Pulls rock in two opposite directions. EX) cutting like
scissors.
Faults: Breaks or cracks in the Earth's crust.
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3 Different types:
Normal Fault: Hanging wall slips down while the foot wall stays in
place.
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Reverse Fault: Hanging wall is pushed up while the foot wall stays
in place.
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Strike-Slip Fault: Rocks on either side of the fault slip past each
other. Sideways, in opposite directions.
Folds: bends in the rock that form when compression shortens and thickens
Earth's crust
 Anticline: A fold that bends upwards. EX) An anthill
 Syncline: A fold that bends downward into a 'V' shape. EX) A
sinkhole
Fault-Block Mountain: As the hanging wall of each normal fault slips
downward the block in between now stands above the surrounding valleys.
Plateau: A large area of flat land elevated high above sea level. Forces in
the crust push the rock upwards.
Chapter 4 Lesson 2:
Earthquake: Is the shaking and trembling that results from the movement
beneath Earth’s surface.
~Seismic waves travel through Earth carrying energy released by an
earthquake.
Focus: The area beneath Earth's
surface where rock that was under
stress begins to break or move.
Epicenter: Point on the surface
directly above the focus.
P-waves: Primary waves, firsts set of waves. Move like an accordion
(compress and expand). Can travel though liquids and solids.
S-waves: Secondary waves second set of waves. Vibrate from side to side.
Can NOT travel through liquids.
Surface waves: Last set of waves to arrive. When P- and S-waves reach the
surface they become surface waves.
Seismograph: An instrument that records and measures earthquakes seismic
waves.
Modified Mercalli Scale: Rates amount of shaking from an earthquake
based on people's observations, without the use of instruments.
Magnitude: A single number that geologists assign to an earthquake based
on the earthquakes size.
Richter scale: Earliest magnitude scale.
Moment Magnitude Scale: Rates total energy an earthquake releases.
~Geologists use seismic waves to locate an earthquakes epicenter.