Mountain Building

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Deformation: Refers to all changes of a rock body.
Where does most deformation take place? Plate boundaries.
Stress: The force that produces deformation, i.e. compression, tension, etc
Strain: The RESULT of stress: folds, faults, etc.
Types of stress: Compression, tension, & shear.
Compression: --><-- Rocks pushed into each other. Found at CONVERGENT boundaries.
Tension: <-- --> Rocks pulled apart. Found at DIVERGENT boundaries.
Shear: Either one or both rocks slide past each other. No direct contact, found at TRANSFORM boundaries.
What type of fault is the San Andreas? Transform, Right-lateral.
What happens when a fault is parallel to stress? No mountains appear. (no significant uplift)
What happens when a fault "bends" along stress, i.e. is not parallel? Mountains and valleys can appear. (significant uplift)
Elastic deformation: Once stress is removed, rock returns to original position. Like playing with an elastic rubber band.
What can happen when a rock's elastic limit is reached, i.e. its been stretched too much? One of two things: Flow - rock stretches permanently. Fracture - Rock breaks.
Flow is ___ deformation. Ductile (flowing)
Fracture is ____ deformation. Brittle (breakage)
4 Factors that influence deformation: Temperature, time, pressure, rock type.
How can warm/cold temp affect deformation? Warm: Ductile, causes deep rocksCold: Brittle, surface rocks
How does time affect deformation? Quick: BrittleSlow: Ductile
How does rock type affect deformation? Shale & Marble: DuctileGranite & Gneiss: Brittle
Fold is an example of what? Ductile deformation.
Faults are an example of what? Brittle deformation. (breakage has occured)
Arch and trough like features are caused by: Folds (compressional features)
Anticline: Arches.
Syncline: Troughs. U
Fracture are a result of... Brittle deformation (breakage)
Two major types of faults: Dip-slip & Strike-slip.
Dip-slip faults are a result of what two types of stress? Tensional and Compressional (pushing and pulling)
2 Parts of a dip-slip fault : Hanging wall and footwall.
Dip-slip movement is parallel to what? the inclination of fault surface.
2 Dip-slip faults: NormalReverse & Thrust
Normal faults = what kind of stress? Tensional <-- ---> Normal = pulling

Result of normal fault activity: Lengthening of crust.
Hanging wall moves down in what fault type? Normal.
Reverse thrust result of what type of stress? Compressional. --> <--Reverse = pushing.
Hanging wall moves UP in what fault type? REVERSE.
Reverse faults have inclination greater than.... 45 degrees.
Thrust faults are ____ 45 degress. Less than.
Not dip-slip, but.... Strike-slip.
Strike slip involves what type of stress? Shear.
Three ways stress can be shear... Left-lateral, right-lateral, and transform.
When facing a fault, right-lateral means... Crustal block on opposite side of fault is moving right, and vice versa for left-lateral.
Transform fault Motion between two plates. San Andreas is an example.