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