chapter 11-2 Flashcards
(14 cards)
describe the 3 types of forces that act on rock
Tension: force that pulls rocks apart
Compression: force that squeezes rocks together until it folds or breaks
Shearing: force that causes rocks on either side of fault to slide past each other, can cause rocks to break and slip apart or change its shape
how do folds form
form when a compression force shortens earth’s crust
what are anticlines, synclines, and monoclines?
Anticline: folded rock that bends upward into an arch
Syncline: bending downwards to form a valley
Monocline: large, steplike folds in horizontal sedimentary strat, occurs as sedimentary layers folded over a large faulted block
what are faults?
fractures where plates break and move, rock on either side move in different directions, occur along plate boundary
what is a normal fault?
form because of tension, plates moving away from each other, one block of rock above fault surface moves downward to rock below fault surface, vertical movement
what are reverse faults and thrust faults?
Reverse faults: high-angle faults with dips greater than 45 degrees, most small and cause local displacements
Thrust faults: all scales, displaced rock layers as far as 50 km, older rocks end up on top of younger rocks
what are strike-slip faults?
shear forces along fault surface, when two plates move sideways past each other, rocks on either side of the fault move past each other without upward or downward movement
what is the transform boundary?
this type of fault between plates, irregular surfaces snag each other causing rocks to be twisted and strained, hinders movement of plates and stress builds up
rocks reach elastic limit causing them to break (earthquakes)
what are mountain ranges/systems/belts?
Mountain range: several mountains of similar shape, age, and structure
Mountain system: group of different mountain ranges in the same region
Mountain belts: mountain ranges and systems along edges of continents
what are folded mountains?
mountains formed primarily by folding
Compressional stress, thrust faulting (fold-and-thrust belts)
what are volcanic mountains?
form along plate boundaries and hot spots, igneous activity forms rock deep in crust and can be uplifted as result of plate motions and isostatic adjustment
wha are fault-block mountains?
where two plates move away from each other (tension forces). Forms when two normal fautls cut through a block of rock, when two normal faults form parallel to each other
Hanging wall slips downward, footwall moves upward
what is downwarped and upwarped?
Downwarped: crust bends downward
Upwarped: crust bows upward
what is a plateau, dome, and basin?
Plateau: landform with relatively high elevation and more-or-less level surface
Dome: when upwarping produces a rough circular structure
Basins: downwarped structures that have a roughly circular shape
