MOVEMENT OF THE MOVEMENT OF THE EARTH’S CRUST EARTH’S CRUST
Dec 16, 2015
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