11.1 Rock 11.1 Rock DeformationDeformation

StressStress

The force per unit area acting on a solid.The force per unit area acting on a solid.

StrainStrain

The change in shape or volume of a body The change in shape or volume of a body of rock as a result of stress.of rock as a result of stress.

AnticlineAnticline

Formed by the upfolding, or arching, of Formed by the upfolding, or arching, of rock layers.rock layers.

SynclinesSynclines

Downfolds, or troughs, found in Downfolds, or troughs, found in association with anticlinesassociation with anticlines

MonoclinesMonoclines

Large, step-like folds in otherwise Large, step-like folds in otherwise horizontal sedimentary stratahorizontal sedimentary strata

Normal faultNormal fault

Occurs when the hanging wall block Occurs when the hanging wall block moves relative to the footwall blockmoves relative to the footwall block

Reverse faultReverse fault

A fault in which the hanging wall block A fault in which the hanging wall block moves up relative to the footwall block.moves up relative to the footwall block.

Thrust faultThrust fault

Reverse faults with dips of less than 45 Reverse faults with dips of less than 45 degreesdegrees

Strike-slip faultStrike-slip fault

Faults in which the movement is parallel Faults in which the movement is parallel to the trend or strike, of the fault surfaceto the trend or strike, of the fault surface

Key ConceptsKey Concepts

The factors that influence the strength of The factors that influence the strength of a rock and how it will deform include a rock and how it will deform include temperature, confining pressure, rock temperature, confining pressure, rock type, and time.type, and time.

Rocks deform permanently in two ways: Rocks deform permanently in two ways: brittle deformation and ductile formation.brittle deformation and ductile formation.

Key ConceptsKey Concepts

Forces that are unable to deform rock Forces that are unable to deform rock when first applied may cause rock to flow when first applied may cause rock to flow if the force is maintained over a long if the force is maintained over a long period of time.period of time.

The three types of stresses that rocks The three types of stresses that rocks commonly undergo are tensional stress, commonly undergo are tensional stress, compressional stress, and shear stress.compressional stress, and shear stress.

Key ConceptsKey Concepts

The three main types of folds are The three main types of folds are anticlines, synclines, and monoclines.anticlines, synclines, and monoclines.

The major types of faults are normal The major types of faults are normal faults, reverse faults, thrust faults, and faults, reverse faults, thrust faults, and strike-slip faults.strike-slip faults.