MOVEMENT OF THE
EARTH’S CRUST
Earth’s crust can be
deformed through:
Faulting
Folding
Uplifting
How does the crust change it’s shape over
time?
• As rocks undergo stress (push-pull force)
they slowly change SHAPE and VOLUME
Stress causes breaking, tilting and folding
►DEFORMATION
3 Types of Deformation
1. Compression - squeezes rocks together
causing crustal rocks to be pushed
higher and deeper.
2. Tension – pulls rocks apart causing
crustal rocks to be thinner in the middle
than at the ends.
3. Shearing – pushes rocks horizontally in
two directions.
FAULTS - a break or crack along
which rocks move
• Hanging Wall – block
of rocks above the
fault.
• Foot Wall – block of
rocks below the fault.
Types of Faults
• Normal Fault : tension causes the hanging wall
to move down relative to the foot wall.
• Reverse Fault : compression causes the
hanging wall to move up relative to the foot wall.
• Strike – Slip Fault : shearing causes the blocks
of rock to move horizontally past one another.
Types
Normal Fault
Reverse Fault
Strike-slip Fault
Fault Block Mountains
• Many Normal Faults
in one area may
create mountains &
valleys.
• Mountains formed by
blocks of rock uplifted
are called fault-block
mountains. Ex :
Grand Tetons, WY
Fold – a bend in a rock
• Sometimes when
stress is applied to
crustal rocks, they
bend but do not break
• Anticline – upward
fold
• Syncline – downward
fold
Normal Faults
Reverse Fault
Strike-Slip Faults
Folds & Faults