Deck 9: Earth Structures - Folds, Faults, and Fabrics

Question 1

Which of the following statements about rock deformation is NOT true?

A) Brittle failure is likely to occur in rocks under low- temperature and low- pressure conditions.
B) Plastic deformation is likely to occur rocks under low- temperature and low- pressure conditions.
C) Plastic deformation is likely to occur in rocks under high- temperature and high- pressure conditions.
D) Elastic deformation is likely to occur if rocks are stressed to only a very minor degree.

Answer 1

B

Question 2

All of the following are evidence of brittle failure EXCEPT:

A) joints.
B) faults.
C) fractures.
D) folds.

Answer 2

D

Question 3

All of the following statements about the history of folded rock are true EXCEPT:

A) folds form in rocks composed of flexible minerals.
B) folds are typically associated with tension at divergent boundaries.
C) folds form in rocks that experienced high pressures and temperatures.
D) folds form in rocks that deformed very slowly.

Answer 3

B

Question 4

Which of the following statements about folds is NOT true?

A) Broad open synclines and anticlines are far more common than tightly folded ones in regions near convergent plate margins.
B) Synclines are concave, trough- like folds, and anticlines are convex, arch- like folds.
C) Folding produces alternating synclines and anticlines with adjacent folds sharing a common limb.
D) Overturned folds are caused by prolonged directed pressure on asymmetrical folds.

Question 5

Resistant sandstone in the trough of a syncline would eventually form which topographic feature?

A) A deep canyon.
B) Topographic ridges.
C) An anticlinal valley.
D) A synclinal valley.

Question 6

A normal fault occurs as a result of:

A) compressional stress, and the hanging wall moves up relative to the footwall.
B) compressional stress, and the hanging wall moves down relative to the footwall.
C) tensional stress, and the hanging wall moves down relative to the footwall.
D) tensional stress, and the hanging wall moves up relative to the footwall.

Question 7

A fold in which the axis intersects the Earth's surface is known as a(n):

A) overturned fold
B) plunging fold.
C) asymmetrical fold.
D) recumbent fold.

Question 8

A region exhibiting symmetrical or open synclines and anticlines is more likely to be located:

A) at the edges of mountain belts in areas that are relatively inactive tectonically.
B) near a transform plate boundary.
C) near a convergent plate boundary.
D) near a divergent plate boundary.

Question 9

Which of the following is true of anticlines and synclines?

A) Anticlines are a result of plastic deformation, whereas synclines are a result of elastic deformation.
B) In anticlines, the oldest rocks are in the center; in synclines, the youngest rocks are in the center.
C) An anticline is present wherever there is a hill; a syncline is present wherever there is a valley.
D) Anticlines are caused by compressive stress, while synclines are caused by tensional stress.

Question 10

Visible evidence of strain deformation is most readily seen in:

A) sedimentary rocks.
B) metamorphic rocks.
C) igneous rocks.
D) equally in all rock types.

Question 11

The general term for the change in shape of a rock when sufficient stress is applied is:

A) strain.
B) compression.
C) shearing.
D) tension.

Question 12

Rocks in which elastic deformation occurs:

A) become fractured but retain their original shape.
B) remain in their deformed shape when the stress is released.
C) return to their original shape when the stress is released.
D) show no response to stress.

Question 13

A thrust fault is the result of:

A) tensional stress, and the hanging wall moves down relative to the footwall.
B) compressional stress, and the hanging wall moves up relative to the footwall.
C) tensional stress, and the hanging wall moves up relative to the footwall.
D) compressional stress, and the hanging wall moves down relative to the footwall.

Question 14

Normal faults are commonly found near:

A) subducting plate boundaries.
B) divergent plate boundaries.
C) transform plate boundaries.
D) continental collision plate boundaries.

Question 15

All of the following are stresses capable of forming joints EXCEPT:

A) earthquakes.
B) contraction of cooling magma.
C) frost wedging.
D) unloading.

Question 16

A rock that undergoes sufficient stress to change its original shape has exceeded its:

A) elastic limit.
B) plastic limit.
C) stress limit.
D) strain limit.

Question 17

Which one of the following rocks will most likely exhibit brittle failure upon stress?

A) Wet shale.
B) Dry sandstone.
C) Wet schist.
D) Wet limestone.

Question 18

The type of fault most commonly found in transform plate boundaries is a:

A) normal fault.
B) dip- slip fault.
C) reverse fault.
D) strike- slip fault.

Question 19

Rocks in which plastic deformation occurs:

A) become fractured but retain their original shape.
B) remain in their deformed shape when the stress is released.
C) show no response to stress.
D) return to their original shape when the stress is released.

Question 20

In geology, the term "stress" refers to:

A) compression of a rock unit.
B) any deformation of a rock unit.
C) forces that might cause deformation of a rock unit.
D) stretching of a rock unit.

Question 21

Why do geologists consider it important to make strike- and- dip measurements on rocks?

Question 22

Which of the following statements concerning horsts and grabens is true?

A) Almost all faults produce either horsts or grabens.
B) Horsts result from normal faults, while grabens result from reverse faults.
C) Horsts and grabens are most commonly produced by compressional stress.
D) Grabens are fault blocks that dropped vertically relative to horsts.

Question 23

What is the difference between symmetrical, asymmetrical, overturned, and recumbent folds?

Question 24

A fold in which the axial plane is horizontal with the surface of the Earth is a(n):

A) asymmetrical fold.
B) overturned fold
C) plunging fold.
D) recumbent fold.

Question 25

Vertical displacement occurs in all of the following EXCEPT:

A) strike- slip faults.
B) normal faults.
C) reverse faults.
D) thrust faults.

Question 26

What is the difference between reverse faults and thrust faults?

Question 27

Mapping the strike and dip of all the rock units in a region is important because:

A) it correlates the locations of all the outcroppings of rocks.
B) it shows the location, elevation, and slope gradient of all the hills and valleys.
C) it establishes the points at which stress was applied to each of the rock units.
D) it delineates the three- dimensional subsurface form of rock structures barely visible at the surface.

Question 28

Rocks subjected to low amounts of stress over a long period of time will most likely:

A) continue to experience elastic deformation.
B) exhibit brittle failure.
C) show no evidence of deformation.
D) exhibit plastic deformation.

Question 29

Which of the following statements concerning stress is NOT true?

A) Shearing stress commonly exists at transform plate margins.
B) Compression, tension, and shearing stress are all capable of causing strain in rock units.
C) Tensional stress commonly exists at continental collision plate boundaries.
D) Compressive stress commonly exists at subducting plate boundaries.

Question 30

Historically, the search for petroleum deposits focused on locating and drilling:

A) the flanks of synclinal structures
B) the crests of synclinal structures.
C) the crests of anticlinal structures.
D) the flanks of anticlinal structures

Question 31

What is the difference between a strike- slip fault and a dip- slip fault?

Question 32

How can geologists determine the type and direction of stress from the orientation of folds and direction of slip in faults?

Question 33

Rocks subjected to relatively high temperatures are more likely to:

A) deform elastically rather than undergo brittle failure.
B) deform plastically rather than elastically.
C) undergo brittle failure rather than plastic deformation.
D) deform elastically rather than plastically.

Question 34

The strike and dip of a rock refer to:

A) the directions in which a rock points.
B) the orientation of the exposed surface of a rock.
C) the orientation of a rock unit in relation to the surface of the Earth.
D) the orientation of a rock unit in relation to neighboring rock units.

Question 35

All of the following features define a fault EXCEPT:

A) abrupt disappearance of a distinctive rock bed.
B) crushed rock along the fault surface.
C) displacement of layers on either side of the fault.
D) symmetrically oriented joint sets extending through this fault.

Question 36

Which of the following statements about domes or basins is true?

A) Domes and basins are probably caused by lateral forces.
B) In a dome, the youngest rocks are in the center.
C) Basins are probably caused by collapse of low- density materials.
D) Domes and basins are probably caused by vertical forces.

Question 37

All of the fault type/plate boundary associations below are correct EXCEPT:

A) reverse faults-subduction zones.
B) thrust faults-convergent plate boundaries.
C) normal faults-continental collisions.
D) strike- slip faults-transform plate boundaries.

Question 38

Why are anticlines and synclines not necessarily evident in the topography as hills and valleys?

Question 39

What are domes and basins? How do they form?