Deck 11: Crags,cracks,and Crumples: Crustal Deformation and Mountain Building

Question 1

Right-lateral and left-lateral are both examples of ________ faults.

A)strike-slip
B)dip-slip
C)oblique-slip
D)reverse

Answer 1

A

Question 2

An episode of mountain building is termed a(n)________.

A)orogeny
B)phylogeny
C)aureole
D)slickenside

Answer 2

A

Question 3

Which of these is NOT one of the components of deformation?

A)displacement
B)rotation
C)distortion
D)dissolution

Answer 3

D

Question 4

A body of rock affected by tensile stress will likely undergo ________.

A)shortening
B)stretching
C)shear strain
D)rotation

Question 5

The term for a change in shape induced by stress is ________.

A)plastic deformation
B)pressure release
C)strain
D)metamorphosis

Question 6

Why do earthquakes occur only above the brittle/plastic transition depth?

A)Below the transition,the rocks are too hot.
B)Below the transition,the rocks break too easily.
C)Above the transition,the rocks are too hot.
D)Above the transition,the rocks will flow.

Question 7

If a fault plane is greater than 35° from horizontal and the hanging-wall block moves upward relative to the footwall block,the fault is called a ________ fault.

A)detachment
B)normal
C)reverse
D)thrust

Question 8

The distinction between joints and faults is that ________.

A)faults are joints that are greater than one square meter in areal extent
B)faults are fractures along which displacement has occurred;displacement does not occur along joints
C)joints are fractures along which displacement has occurred;displacement does not occur along faults
D)there is no distinction;the two terms are synonymous

Question 9

Under which condition would a body of rock be most likely to exhibit brittle behavior?

A)slow rate of deformation
B)low temperature
C)high temperature
D)high pressure

Question 10

Under which of these conditions would a body of rock be more likely to exhibit plastic behavior?

A)low temperature
B)high temperature
C)low pressure
D)high rate of deformation

Question 11

Force per unit area is termed ________.

A)stress
B)strain
C)power
D)work

Question 12

Movement along faults often produces a rock formed from sharply angled rock fragments termed ________.

A)fault gouge
B)rock flour
C)fault breccia
D)slickenside

Question 13

A body of rock affected by compressive stress will likely undergo ________.

A)shortening
B)stretching
C)shear strain
D)rotation

Question 14

How is stress different from strain?

A)Strain is a measure of the total displacement on a fault.
B)Stress is the change in shape of a rock due to applied strain.
C)Strain is the change in shape of a rock due to applied stress.
D)They are not different: stress and strain are synonymous.

Question 15

How is stress different from force?

A)Force is the stress applied per unit area.
B)Stress is the force applied per unit area.
C)Force comes from one direction,while stress comes from all directions.
D)They are not different: stress and force are synonymous.

Question 16

A polished surface produced by scraping of rock along a fault is termed a(n)________.

A)orogeny
B)phylogeny
C)aureole
D)slickenside

Question 17

Normal,reverse,and thrust are all examples of ________ faults.

A)strike-slip
B)dip-slip
C)oblique-slip
D)lateral

Question 18

Which of these features would NOT help a geologist recognize a fault?

A)different rock units juxtaposed against each other
B)a small step on the landscape
C)a shattered rock consisting of visible angular fragments
D)regularly spaced quartz veins

Question 19

How does the rate at which a body of rock is deformed affect its behavior?

A)A rock deformed quickly is likely to exhibit brittle behavior.
B)A rock deformed slowly is likely to exhibit brittle behavior.
C)The rate of deformation has no effect on a rock's behavior.
D)The rate of deformation is important only below the brittle/plastic transition.

Question 20

Regularly spaced joints in an outcrop may indicate that an area ________.

A)is under intense shear stress
B)has experienced compressional stress
C)is underlain by a thrust fault
D)is formed from rocks that were once at great depth

Question 21

A fold shaped like an elongate arch is a(n)________.

A)anticline
B)basin
C)dome
D)syncline

Question 22

A geologist's compass differs from the more widely known orienteering compass in that the geologist's compass ________.

A)possesses an inclinometer,allowing the user to measure dip and plunge angles
B)contains a barometer that warns the geologist of approaching storms
C)can chemically analyze rock samples in the field
D)needle points directly toward geographic north rather than geomagnetic north

Question 23

Normal faults assume a more shallow dip angle with depth;when the fault plane becomes nearly horizontal,these faults are termed ________.

A)thrusts
B)folds
C)detachments
D)fault scarps

Question 24

If a fault plane is less than 35° from horizontal and the hanging-wall block moves upward relative to the footwall block,the fault is a ________ fault.

A)detachment
B)normal
C)reverse
D)thrust

Question 25

Which of these properly illustrates the principle of isostasy?

A)High-density crust floats on top of low-density mantle.
B)Mountains stand high because they are gravitationally balanced by their deep crustal roots.
C)When weight is added to the crust,the crust responds by rebounding upward.
D)When material is removed from the crust,the crust maintains the new,lower elevation.

Question 26

A fold shaped like an elongate trough is a(n)________.

A)anticline
B)basin
C)dome
D)syncline

Question 27

Which fault below could result from both strike-slip and dip-slip stresses?

A)A
B)B
C)C
D)D

Question 28

Shear stress at sufficient depth within a fault plane can induce plastic shear,forming a fine-grained metamorphic rock named ________.

A)ignimbrite
B)gneiss
C)mylonite
D)migmatite

Question 29

A fold shaped like an upside-down bowl is a(n)________.

A)anticline
B)basin
C)dome
D)syncline

Question 30

On a geologic map,if the contacts between sedimentary rock units form a series of parallel lines,with the youngest unit in the center,the underlying structure is a ________.

A)horizontal anticline
B)plunging anticline
C)horizontal syncline
D)plunging syncline

Question 31

Orogenesis (mountain building)leads to the production of ________.

A)metamorphic rocks
B)igneous and sedimentary rocks
C)metamorphic and igneous rocks
D)igneous,metamorphic,and sedimentary rocks

Question 32

In a ________ fault,the fault plane is nonvertical and the hanging-wall block moves downward relative to the footwall block.

A)detachment
B)normal
C)reverse
D)thrust

Question 33

In the map below,the vertical,north-south trending fault is a ________ fault.

A)normal dip-slip
B)reverse dip-slip
C)right-lateral strike-slip
D)left-lateral strike-slip

Question 34

How is tectonic foliation,such as elongation of quartz grains,oriented relative to the original bedding plane of a body of rock?

A)Foliation is parallel to original bedding.
B)Foliation is at about 45° to original bedding.
C)Foliation is perpendicular to original bedding.
D)Foliation can be at a variety of angles to original bedding.

Question 35

On a geologic map,if the contacts between sedimentary rock units form a bull's-eye pattern of concentric circles,with the youngest unit in the center,the underlying structure is a(n)________.

A)anticline
B)basin
C)dome
D)syncline

Question 36

It is possible for offset along an oblique-slip fault to have both ________ and ________ components.

A)normal;reverse
B)right-lateral;left-lateral
C)normal;left-lateral
D)reverse;thrust

Question 37

The sides of a fold,where curvature is at a minimum,are termed ________.

A)branches
B)limbs
C)axial planes
D)hinges

Question 38

The central portion of high curvature on a fold is termed the fold ________.

A)limb
B)hinge
C)midsection
D)thorax

Question 39

A fold shaped like a right-side-up bowl is a(n)________.

A)anticline
B)basin
C)dome
D)syncline

Question 40

On a geologic map,if the contacts between sedimentary rock units form a bull's-eye pattern of concentric circles,with the oldest unit in the center,the underlying structure is a(n)________.

A)anticline
B)basin
C)dome
D)syncline

Question 41

Mountain ranges are NOT associated with ________.

A)convergent plate boundaries
B)divergent plate boundaries
C)transform plate boundaries
D)hot spots

Question 42

How were nearly all of the present mountain ranges formed?

A)tilting of rift blocks into half grabens
B)compression of areas along transform plate boundaries
C)addition of accreted terranes to the continents
D)repeated cycles of collision and rifting

Question 43

Which of these is NOT characteristic of deformation brought on by orogeny?

A)metamorphosed rock
B)folded rock
C)faulted rock
D)isostatic rebound

Question 44

Continental crust is typically 35 km thick,but may be up to ________ thick under mountain ranges.

A)40 km
B)70 km
C)200 km
D)400 km

Question 45

Regions of continents that have NOT been subjected to orogeny during the past one billion years are termed ________.

A)exotic terranes
B)accreted terranes
C)cratons
D)cratonic platforms

Question 46

Regions where Precambrian metamorphic rocks are exposed at the surface are termed ________.

A)shields
B)cratonic platforms
C)convergent margins
D)domes

Question 47

The balance between the weight of a mountain range and the buoyancy provided by the underlying mantle is termed ________.

A)punctuated equilibrium
B)homeostatic equilibrium
C)isostatic equilibrium
D)osmotic equilibrium

Question 48

What is the primary reason why mountains substantially taller than Mt.Everest are unlikely to arise on Earth?

A)The high geothermal gradient in the crust causes mountains to collapse under their own weight.
B)Exhumation proceeds faster than uplift.
C)Extreme elevations cause chemical weathering to outpace uplift.
D)Uplift is limited by the rate of subduction.

Question 49

The outer portion of a craton,where deformed rocks are covered by sediments,is termed the ________.

A)shield
B)cratonic platform
C)convergent margin
D)exotic terrane

Question 50

There are many ways in which uplift can occur,but all of them reflect ________.

A)compressional forces
B)the effects of weathering and erosion
C)subduction zone processes
D)the lithosphere's tendency to achieve isostasy