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CHSCheyScienceCh2S1
Question | Answer |
---|---|
earthquake | the shaking that results from the movement of rock beneath Earth's surface. |
Two powerful forces that change rock in Earth's crust are: | -squeezing -pulling |
stress | a force that acts on rock to change its shape or volume. |
volume | the amount of space an object takes up. |
shearing | stress that pushes a mass of rock in two opposite directions. (related to transform boundaries) |
tension | stress that stretches rock so that it becomes thinner in the center. (related to divergent boundaries) |
compression | force that squeezes rock until it folds or breaks. |
If shearing continues to tug at the slab of rock, what will happen to the rock? | The rock will break; the two parts will move in opposite directions. |
deformation | any change in the volume or shape in Earth's crust. Most changes in the crust occur so slowly that they cannot be observed directly. |
How does deformation change Earth's surface? | Deformation causes Earth's surface to bend, stretch, break, tilt, fold, and slide. |
How do the stress forces affect rock? | Shearing - the rock breaks and slip apart Tension - Rock stretches and becomes thin in center Compression - Rock squeezes until it folds or breaks |
fault | A break in the crust where slabs of crust slip past each other. |
strike-slip fault | Type of fault where rocks on either side move past each other sideways w/ little up-or-down motion. |
normal fault; what is it caused by? | Type of fault where the hanging wall slides downward; caused by tension in the crust. |
hanging wall | The block of rock that forms the upper half of a fault. |
footwall | The block of rock that forms the lower half of a fault. |
reverse fault; what is it caused by? | Type of fault where hanging wall slides upward; caused by compression in crust. |
What are the three types of fault? What force of deformation produces each? | Reverse - compression normal - tension strike-slip - shearing |
Why do faults form and where do they occur? | Faults usually occur along plate boundaries, where the forces of plate motion compress, pull, or shear the crust so much that the crust breaks. |
What is friction? | The force that opposes the motion of one surface as it moves across another surface. |
What occurs when friction on a fault is low? | The rocks on both sides of the fault slide by each other without much sticking. |
What occurs when friction on a fault is medium? | Sides of fault jam together, from time to time they jerk free; small earthquakes occur. |
What occurs when friction on a fault is high? | Sides of fault lock together and do not move. Stress increases until it it strong enough to overcome force of friction. Larger and/or more frequent earthquakes will occur. |
fault-block mountain | A mountain that forms where a normal fault uplifts a block of rock. |
How does the process of a fault-block mountain begin? | Where two plates move away from each other, tension forces create many normal faults, when two normal faults form parallel to each other, block of rock is left lying between them. As the hanging wall of each normal fault slips down, the block moves up. |
folds | A bend in rock that forms where part of Earth's crust is compressed. |
How does the compression of two plates cause an earthquake? | Folding rock can fracture and produce faults. |
anticline | An upward fold in rock formed by compression of Earth's crust. |
syncline | A downward fold in rock formed by compression of Earth's crust. |
plateau | A landform that has a more or less level surface and is elevated high above sea level. |
How does movement along faults change Earth's surface? | Forms hills and mountain ranges. |