2 Earth’s crust can be deformed through: FaultingFoldingUplifting
3 How does the crust change it’s shape over time? As rocks undergo stress (push-pull force)they slowly change SHAPE and VOLUMEStress causes breaking, tilting and folding►DEFORMATION
4 3 Types of DeformationCompression - squeezes rocks together causing crustal rocks to be pushed higher and deeper.Tension – pulls rocks apart causing crustal rocks to be thinner in the middle than at the ends.Shearing – pushes rocks horizontally in two directions.
5 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.
6 Types of FaultsNormal 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.
8 Many Normal Faults in one area may create mountains & valleys. Fault Block MountainsMany 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
9 Fold – a bend in a rockSometimes when stress is applied to crustal rocks, they bend but do not breakAnticline – upward foldSyncline – downward fold