Deck 9: Crags, cracks, and Crumples: Crustal Deformation and Mountain Building

Question 1

Change in shape,induced by stress,is termed ____________.

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

Answer 1

C

Question 2

Earthquakes only occur ____________ the brittle/ductile transition depth.

A) above
B) below
C) at or near

Answer 2

A

Question 3

During deformation,rocks can undergo a change in all of the following except ____________ .

A) location
B) composition
C) orientation
D) shape

Answer 3

B

Question 4

A body of rock to which a sudden,rapid stress has been applied is more likely to exhibit ____________ than is a body of rock subjected to a gradually applied stress.

A) brittle behavior
B) ductile behavior

Question 5

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

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

Question 6

Why might a geologist looking at exposed rock determine that the rock is undeformed?

A) The layers are cut by joints.
B) The grains present are not spherical.
C) The clay flakes are parallel to the bedding.
D) The clay flakes exhibit slaty cleavage.

Question 7

A joint always occurs as a single,isolated plane within a rock.

Question 8

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

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

Question 9

Which of the following statements is true regarding rock deformation inside the Earth?

A) Heat makes materials harder to deform.
B) High pressures make rock act more brittlely.
C) A sudden change in shape causes ductile deformation.
D) Softer rock types deform ductilely.

Question 10

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

A) shortening
B) stretching
C) shear strain

Question 11

Most fault surfaces,like joints,are roughly planar in orientation.

Question 12

A hot body of rock is more likely to exhibit ____________ than is a cold body of rock.

A) brittle behavior
B) ductile behavior

Question 13

Force per unit area is termed ____________.

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

Question 14

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

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

Question 15

Right lateral and left lateral are both examples of ____________ faults.

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

Question 16

Movement along faults often produces sharply angled rock fragments termed ____________.

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

Question 17

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

Question 18

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

A) shortening
B) stretching
C) shear strain

Question 19

A body of rock under high pressure is more likely to exhibit ____________ than is a body of rock at low pressure.

A) brittle behavior
B) ductile behavior

Question 20

Mt.Everest,the tallest mountain above sea level,is located on the continent of ____________.

A) Africa
B) Asia
C) North America
D) Europe

Question 21

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 22

Tectonic foliation,such as elongation of quartz grains,always occurs parallel to the original bedding plane of a body of rock.

Question 23

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

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

Question 24

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 25

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

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

Question 26

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

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

Question 27

____________ may help a geologist recognize a fault.

A) Displacement
B) Fault scarps
C) Breccia
D) All of the above are correct.

Question 28

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

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

Question 29

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 30

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

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

Question 31

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 32

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

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

Question 33

If a geologist was examining a line that ran across a rock face,how could he or she best determine whether the line was a joint or fault?

A) by consulting a geologic map of the area
B) by looking for telltale signs of movement on either side of the line
C) by measuring the strike and dip of the line
D) by looking for signs of erosion

Question 34

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 35

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

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

Question 36

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

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

Question 37

Motion along all faults is either strike slip or dip slip; combinations of these two types of displacement are never found together in a single fault.

Question 38

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

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

Question 39

Within a platform,sedimentary rocks always have a horizontal orientation.

Question 40

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 41

Why do mountains occur in distinctive belts?

A) Rifts are linear features.
B) Plates move linearly over hot spots.
C) The processes that create mountains are linear.
D) Both a and c are correct.
E) Both b and c are correct.

Question 42

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 43

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

A) shield
B) platform
C) convergent margin

Question 44

Why are Mt.Everest and the surrounding Himalayan Mountains still growing?

A) They experience no erosion.
B) The Indian Plate is still moving.
C) India is made of stronger lithosphere than Asia.
D) Both a and c are correct.
E) Both b and c are correct.

Question 45

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(n)____________.

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

Question 46

Which of the following must occur for the elevation of a mountain range to increase over time?

A) There must be an absence of erosion.
B) The rate of erosion must be less than the rate of uplift.
C) The rate of uplift must be less than the rate of erosion.
D) Uplift and erosion must cease, but the asthenosphere must expand.

Question 47

Valleys and hillsides carved by glaciers are generally more ____________ in comparison to those produced by rivers and streams.

A) steep sided
B) shallow sided

Question 48

In order to maintain isostasy,what must occur after new igneous rock is added to the crust (either on top of or intruded into)?

A) The asthenosphere must sink.
B) The base of the lithosphere must sink in equal proportional to how much the surface has risen.
C) The base of the lithosphere must sink but not as much as the surface has risen.
D) The surface must rise in equal proportion to how much the asthenosphere has sunk.

Question 49

Deformation brought on by orogeny can ____________.

A) metamorphose rock
B) produce folds in rock
C) produce faulting in rock
D) All of the above are correct.

Question 50

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

A) shields
B) platforms
C) convergent margins

Question 51

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

A) metamorphic rocks only
B) igneous rocks only
C) sedimentary rocks only
D) any of the three rock types listed above

Question 52

Theoretically,there is no reason why mountains substantially taller than Mt.Everest might not one day arise on Earth.

Question 53

Nearly all of the present mountain ranges are the products of single orogenic events.

Question 54

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

A) 20%
B) 50%
C) 100%
D) 200%

Question 55

Why are blocks of wood floating in water a good analogy for mountains floating on the asthenosphere?

A) The materials on which they float have the same properties.
B) A larger block of wood has more "showing" above the water.
C) The mass of the displaced water is equal to the mass of the block below water.
D) The blocks have positive buoyancy.

Question 56

Why do offshore volcanic arcs collide with and suture to an overriding plate?

A) They are too buoyant to subduct.
B) The melting involved in subduction sutures them to the plate.
C) Their predominant rock type is the same as the overriding plate.
D) When they collide, subduction stops.

Question 57

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

Question 58

Why don't we have mountains as tall as Olympus Mons,found on Mars,on Earth?

A) Our high geothermal gradient causes crustal rocks to act ductilely at mid-crust depths.
B) The greater gravity on Earth prevents mountains from reaching such heights.
C) Mars doesn't have a geothermal gradient.
D) Mars has rock types more conducive to constructing such large mountains.

Question 59

Mountain ranges are important sites for the formation of igneous and metamorphic rocks,but do not have any apparent relationship with the formation of sedimentary rocks.

Question 60

Mountain ranges are associated with modern and ancient convergent-plate boundaries,but do not form in association with either divergent- or transform-plate boundaries.