Ch.4: Forces in Crust

stress

force that acts on rock to change shape or volume

energy

stress adds it to rock which is stored for later until it breaks

tension

stress force that pulls on crust and thins the rock in the middle

compression

stress force that squeezes the rock until it folds or breaks

Shearing

stress that pushes mass of rock in two opposite directions

faults occur…

when enough stress builds up in trock, the rock breaks

Normal Faults

tension pulls rock apart in Earth’s crust, hanging wall slips down

hanging wall

block of rock that sits over the fault

footwall

block of rock that sits under fault

reverse faults

compression pushes rock together and hanging wall moves up and footwall goes down

strike-slip faults

shearing, rock on either side of fault slips past each other sideways

folds in crust

breaks in rock that form when compression shortens and thickens crust

anticlines

rock bends upward into arch

synclines

rock bends downward into V shape

anticlines and synclines

results of compression/ divergent boundaries

folded mountains

results when there is collision of two plates and compression of crust/ convergent boundaries

fault block mountains

form when two plates move away from each other in tension

formation of fault block mountains

hanging wall of normal fault slips down and the block in between now stacks above the surrounding valleys

plateaus

large area of land raised high above sea level, convergent boundaries

divergent boundary

normal fault line

convergent boundary

reverse fault line

transform boundary

strike-slip fault line

constructive plate boundaries

occur when 2 plates move away from each other

destructive plate boundaries

occurs when oceanic plate is forced under (or subducts) a continental plate