1. Deformation is folding or fracturing of rocks that are subjected to stresses greater than its own strength.
2. Confining pressure influences the way rocks deform by reducing the rocks volume and making the rock more compact. These rocks are buried and subjected to the force exerted by the load above. It is uniform in all directions , where confining pressure and temperature is low, rocks are brittle at great depths where confining pressure and temperature are high rocks become ductile.
3. In simple terms, the difference between brittle and ductile deformation is that brittle fractures and ductile flows.
4. Compressional stress is rocks being pushed together while tensional stresses is rocks being pulled apart. Normal faults result from tensional forces while reverse faults result from compressional forces. Fault Block Mountains result from tensional forces and folded mountains result from compressional forces. When stresses are acting t a shorten a rock body they are compressional stresses while when stresses are acting in opposing directions, they tend to elongate r pull apart the rock unit it is tensional stresses.
5. Elastic deformation is different from plastic deformation by changes resulting form elastic are reversible and changes resulting from plastic are permanent (the size and shape of the rock are altered through folding or faulting).
6. Three factors that determine how rocks will behave when exposed to stresses that exceed their strength are the environment, the strength of the materials, and time. The environment strongly influences how a rock will deform. In near-surface environments, where temperatures and pressures are low, most rocks exhibit brittle fracture. In high temperatures and high pressure regions deep beneath the crust the same rocks will deform by ductile flow. With the strength, some rocks such as gypsum are very weak and are more likely to flow under conditions that stronger rock fail by brittle fracture. Time influences it by rocks that would fracture when stress is applied rapidly are known to flow when stress is applied gradually over a long time span.
7. An outcrop is sites where bedrock is exposed at the surface.
8. Two measurements that are used to establish the orientation of deformed strata are strike and dip. Strike is the trend, or direction of the strata, while dip is the angle of inclination of the bedding surface.
9. Anticlines are sedimentary upfolds while synclines are sedimentary downfolds. Domes are circular anticlines while basins are circular synclines. Anticlines are sedimentary downfolds while domes are circular anticlines.
10. A monocline is different form an anticline by a monocline only consists of one arm while an anticline has more than one arm.
11. The Black Hills of South Dakota are a good example of a upwarped mountain or dome.
12. The movements that occur along normal faults are that the foot wall moves up and the hanging wall moves down while with reverse faults the hanging wall moves up and the foot wall moves down. The type of stress indicated by normal faults are tensional force and by reverse faults are compressional forces.
13. The fault shown in Figure 15.17 is a reverse fault.
14. The type of fault that is shown in the chapter opening photo is the strike slip or transform faults.
15. A harst is an elongate, uplifted block of crust bounded by faults. A graben is a valley formed by the downward displacement of a fault-bounded block. A graben valley forms by it is bounded by normal faults and drops as the plates separate. An example of a graben is the Great Rift Valley.
16. The type of faults that are associated with fault-block mountains are normal faults.
17. The fault illustrated by Figure 15.23 is a thrust fault.
18. The San Andreas fault is an excellent example of a transform fault.
19. Normal faulting predominate in divergent plate boundaries. Reverse faulting predominate in convergent plate boundaries. Strike-slip faulting predominate in transform plate boundaries.
20. Joints are different from faults by joints are fractures along which no appreciable displacement has occurred. Faults are fractures in the crust along which appreciable displacement has taken place.