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MOVEMENT OF THE MOVEMENT OF THE EARTH’S CRUSTEARTH’S CRUST
Earth’s crust can be Earth’s crust can be deformed through:deformed through:
FaultingFaulting
FoldingFolding
UpliftingUplifting
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 Deformation3 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.
FAULTSFAULTS - - a break or crack along a break or crack along which rocks movewhich rocks move
• Hanging Wall – block of rocks above the fault.
• Foot Wall – block of rocks below the fault.
Types of FaultsTypes 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.
TypesTypes
Normal Fault Reverse Fault Strike-slip Fault
Fault Block MountainsFault 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 rockFold – 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 FaultsNormal Faults
Reverse FaultReverse Fault
Strike-Slip FaultsStrike-Slip Faults
Folds & FaultsFolds & Faults
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