Chaper 10 Test Flashcards
Deformation
a general term that refers to all changes in the shape or position of a rock body in response to stress
How compressional stress changes a rock body?
it squeezes a rock and shortens a rock body
How does tensional stress change a rock body?
it pulls apart a rock unit and lengthens it
How does shear stress change a rock body?
it produces a motion similar to slippage that occurs between individual playing cards when the top of the stack is moved relative to the bottom
What type of tectonic boundary is associated with compressional stress?
Convergent plate boundary
What type of tectonic boundary is associated with tensional stress?
Divergent plate boundaries
What type of boundary is associated with shear stress?
Differential stress
Fault
fractures in rocks, along which displacement as occurred
Joint
fractures in rock where there has been no rock movement
What type of environment does faults occur?
can be recognized in road cuts where sedimentary beds have been offset a few meters
What type of environment does joints occur?
when rocks in the outermost crust are deformed as tensional stresses cause the rock to fail by brittle fracture
Domes
upwarped circular features where the oldest rocks are in the center. Ex: The Black Hills of western South Dakota
Basins
downwarped circular features where youngest rocks are in the center. Ex: Basins of Michigan and Illinois
Normal fault
characterized by the hanging wall moving down relative to footwall. Associated with tensional stress as the rocks pull apart
Reverse fault
characterized by the hanging wall moving up relative to the footwall. Associated with compressional stress as the crust shortens
Strike slip
characterized by placement that is horizontal and parallel to the strike of the fault. Ex: San Francisco earthquake of 1906
Elastic deformation
the rock returns to nearly its original size and shape when the stress is removed
Ductile deformation
a type of solid-state flow that produces a change in the shape of an object without fracturing
Brittle deformation
rocks that break into smaller pieces
Monoclines
large, steplike folds in otherwise horizontal sedimentary strata
Synclines
downfolded or troughs of rock layers; youngest strata are in the center
Anticlines
usually arise by upfolding, or arching, of sedimentary layers and are sometimes spectacularly displayed along highways that have been cut through deformed strata. Oldest strata are in the center
Hanging wall
rock surface above the fault
Foot wall
rock surface below the fault
Dip-slip fault
occur when movement is parallel to the inclination. Fault block mountains
Right-lateral
as you face the fault, the opposite side of the fault moves to the right
Left-lateral
as you face the fault, the opposite side of the fault moves to the left
What type of stress occurs in strike-slip fault?
Transform faults
