Practice 2nd Exam (Topics: Volcanic rocks, Streams, Landslide)
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. Pele’s hair ____________.
a. consists of thin strands of basaltic volcanic glass
b. acquires aerodynamic torpedo-like shapes during flight out of the volcanic vent
c. forms only at the leading edge of basaltic lava flows
d. was instrumental in scoring the winning goal to defeat Uruguay in the 1958 World Cup
finals
2. A fast-moving flow consisting of a mixture of water and volcaniclastic debris is called a ____________.
a. lahar
c. flood basalt
b. glowing avalanche
d. stratovolcano
3. Pahoehoe ____________.
a. forms when a basaltic lava flow ceases flowing and solidifies simultaneously
b. has a smoother texture than a’a’
c. is easier to walk on than a’a’ is
d. All of the above are correct.
4. Common volcanic gases include ____________.
a. water vapor, carbon dioxide, and sulfur dioxide
b. oxygen, ozone, and water vapor
c. oxygen, hydrogen, and neon
d. carbon dioxide, carbon monoxide, and oxygen
5. Basaltic lavas ____________.
a. contain more iron and magnesium than rhyolitic lavas
b. contain more silica than rhyolitic lavas
c. are more viscous than rhyolitic lavas
d. contain a greater proportion of trapped volatiles than rhyolitic lavas
6. Mafic lavas are distinguished by ____________.
a. light coloration
c. high viscosity
b. low viscosity
d. high silica content
7. The lithification of material from a pyroclastic flow forms a rock called ____________.
a. Metabasalts
c. migmatite
b. Ignimbrite
d. tuff
8. Nonviolent eruptions characterized by extensive flows of basaltic lava are termed ____________.
a. Pyroclastic
c. explosive
b. Effusive
9. Of the three primary forms of subaerial volcanoes, ___ consist of alternating layers of tephra and
solidified lava.
a. Stratovolcanoes
c. shield volcanoes
b. cinder cones
10. Of the three primary forms of subaerial volcanoes, _______ are sometimes referred to as “composite
volcanoes.”
a. Stratovolcanoes
c. shield volcanoes
b. cinder cones
11. Whether an eruption will primarily produce lava flows or pyroclastic debris is influenced by the
____________.
a. viscosity of the lava
c. proportion of volatiles within the lava
b. composition of the lava
d. All of the above are correct.
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12. As compared to subaerial basaltic lavas, submarine basaltic lavas differ in that they ____________.
a. always produce violent pyroclastic debris flows
b. produce large crystals of pyroxene and plagioclase
c. form pillow-like mounds because they cannot flow as far from their source
d. All of the above are correct.
13. The Columbia River Plateau is an example of a ____________.
a. caldera
c. flood basalt province
b. fissure
d. hot spot
14. The Hawaiian island chain is an example of a(n) ____________.
a. island volcanic arc
c. hot-spot island chain
b. continental volcanic arc
d. stratovolcanic assembly
15. Which national park has a large volcanic caldera formed by a very large explosive eruption 640,000
years ago?
a. Acadia
c. Great Smoky Mountains
b. Carlsbad Caverns
d. Yellowstone
16. Hot-spot volcanoes ____________.
a. can arise from the ocean floor
b. can arise on continents
c. may arise in the interior of lithospheric plates
d. All of the above are correct.
17. At continental rifts, vast bodies of basaltic lava flow forth from fissures, forming ____________.
a. flood basalts
c. ash-fall tuffs
b. pyroclastic flows
18. Mt. St. Helens killed a geologist studying the volcano because ____________.
a. the geologist disregarded orders to keep a safe distance from the vent
b. the eruption produced a greater volume of ash than anyone predicted
c. a landslide produced a lateral blast of volcaniclastic debris that no one anticipated
d. lahars swept down all sides of the volcano and buried all towns within 100 km
19. The greatest hazard to human life associated with volcanoes is ____________.
a. flowing lava
c. falling ash
b. volcanic gas
d. pyroclastic flows
20. What signs do scientists look for when predicting volcanic eruptions?
a. changes in earthquake activity
c. changes in shape
b. increases in gas and steam emission
d. All of the above are correct.
21. Which of the following is NOT an effect volcanic eruptions can have on climate?
a. They can dim the stars.
b. They can lower temperatures for at least a season.
c. They can increase the growth rate of tree rings.
d. They can cause more radiant sunsets.
22. Different types of mass wasting have different velocities.
a. true
b. false
23. ____________occur(s) when a semicoherent mass of material moves downslope on a failure surface.
a. Avalanches
c. Creep
b. Slumps
d. Solifluction
24. Which type of mass movement includes a large proportion of ash derived from a volcanic eruption?
a. Stromboli
c. debris flow
b. lahar
d. Wadi
25. Which of the following types of mass movement is the least coherent internally?
a. slump
c. rock slide
b. creep
d. mudflow
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26. Which of the following types of mass movement is actually a landslide?
a. slump
c. rock slide
b. creep
d. mudflow
27. Large ____________ may trigger tsunamis.
a. lahars
c. avalanches
b. submarine mass movements
d. rockfalls
28. ____________occur(s) where thawed sediments move downslope over permafrost.
a. Avalanches
c. Creep
b. Slumps
d. Solifluction
29. Which of the following types of mass movement takes place most gradually?
a. slump
c. rock slide
b. creep
d. mudflow
30. A warming climate at both high elevations and latitudes would increase the area in which solifluction
occurs.
a. True
b. False
31. The principal difference between a lahar and a mudflow is the ____________.
a. shape of the path taken by the moving mass
b. grain size of the moving mass
c. lahar’s abundant water, compared to the dry mudflow
d. lahar’s pyroclastic debris content from a volcanic eruption
32. Which of the following types of mass movement is likely to move most rapidly?
a. slump
c. rock slide
b. creep
d. Solifluction
33. To the geologist, ____________.
a. landslides and mass movements are the same thing
b. all mass movements are landslides, but not all landslides are mass movements
c. all landslides are mass movements, but not all mass movements are landslides
d. mass movements differ from landslides in that a greater mass of material moves during a
mass movement than during a landslide
34. You are mapping a new road-cut made through a wide, sloped plain. The road-cut exposes uniformly
dipping sedimentary rocks. Which geologic feature listed below would indicate that creep had been
occurring in the area before the road-cut was made?
a. a layer of rounded clasts in the bedrock
b. greater chemical weathering near the top of the newly exposed beds
c. a uniform tilting of the sedimentary beds toward the downslope direction of the sloped
plain.
d. small ravines and ephemeral channels in the plain
35. All regions are susceptible to mass movements.
a. true
b. False
36. Which of the following increases the risk of mass movement?
a. adding a small amount of moisture to dry sediment
b. waves breaking on a beach before reaching a vertical sea cliff
c. saturating the sediment with water
d. reducing the steepness of the slope
37. Fires and deforestation may not lead to slope failure.
a. true
b. False
38. The immediate cause of mass movement is ____________.
a. magnetic attraction
c. water content
b. gravitational attraction
d. frictional resistance
39. Slope stability is determined by which two forces?
a. Downslope sliding and resistance
c. resistance and gravity
b. gravity and friction
d. downslope and friction
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40. Well-rounded sand has a steeper angle of repose than irregularly shaped gravel.
a. true
b. False
41. Unstable slopes start to move when the ___ force exceeds the ____ force that holds the material in place.
a. downslope; gravity
c. downslope; frictional resistance
b. resistance; downslope
d. gravity; resistance
42. Moisture among sediment grains ____________.
a. always increases the likelihood of mass wasting
b. always decreases the likelihood of mass wasting
c. can promote stability if present in small amounts, but promotes mass wasting if sediment is saturated
d. can promote stability if the grains are saturated, but the presence of a small amount has little effect on
the likelihood of mass wasting
43. The flow of water from a spring on a hillside increases. Why does this make the hillside less stable?
a. The increased spring flow will precipitate-out more minerals and make the slope heavier.
b. The increased spring flow will cool the hillside and discourage plant growth that normally
stabilizes a hillside.
c. The increased spring flow will saturate more of the hillside and thereby increase its instability.
44.
45.
46.
47.
d. All of the above are correct.
Ground shaking can transform wet sediments into liquid-like slurries in a process known as
____________.
a. liquefaction
c. undercutting
b. slumping
d. sloping
Which type of bedrock provides the greatest risk of landslide?
a. granite
c. sandstone
b. gneiss
d. shale
____________ may help stabilize slopes to prevent mass wasting.
a. Revegetation
c. Preventing undercutting
b. Regrading
d. All of the above are correct.
Highway departments sometimes drill holes into roadside slopes excavated into regolith or weak rock.
The holes are drilled to angle slightly upward from the curb, and after drilling is complete a perforated
pipe is installed in each hole. How will this help stabilize the roadside slopes?
a. Air within the pipes will help dry out the slope.
b. Minerals will precipitate into the pipe where water enters it, making the slope stronger.
c. Air and bacteria that enter the hillside via the pipe will introduce rooting systems that will stabililize
the slope.
d. Groundwater will flow into the pipes and drain out, thus decreasing the saturation of the slope.
48. Which of the following factors increase(s) the risk of mass movement?
a. Nearby earthquakes
c. adding weight to the top of a hill
b. excavation into the base of a hill
d. All of the above
49. Conditions such as ____________ may exacerbate a developing slump.
a. persistent rain
c. earthquake aftershocks
b. rising floodwaters
d. All of the above are correct.
50. In uniform sediments with a relatively constant slope at the surface, a ____________ drainage network
is expected.
a. dendritic
c. rectangular
b. radial
d. trellis
51. The primary stream fed by tributaries within a drainage basin is termed a ____________.
a. lead stream
c. taproot stream
b. trunk stream
d. pirate stream
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52. In a region with prominent orthogonal sets of joints, a ____________ drainage network is expected.
a. dendritic
c. rectangular
b. radial
d. trellis
53. In a region characterized by a parallel series of ridges and valleys, a ____________ drainage network is
expected.
a. dendritic
c. rectangular
b. radial
d. trellis
54. Ephemeral streams ____________.
a. consist of a series of intertwined channels that are overloaded with sediment
b. have flowing water either episodically or during a portion of the year
c. have a channel that is highly sinuous (curvy)
d. divert flow from streams they have intersected through stream erosion.
55. Although the Nile River is longer, the Amazon River has the greatest discharge of any stream on Earth.
a. true
b. false
56. The deepest part of a mature river channel is where the water usually flows the slowest.
a. true
b. False
57. As the velocity of flow increases, ____________.
a. flow tends to become more turbulent
b. the maximum flow velocity increases
c. suspended sediment does not get deposited
d. All of the above are correct.
58. The discharge of a river traveling through a humid region will typically ____________ downstream; the
discharge of a river traveling through an arid region will typically ____________ downstream.
a. increase; increase
c. increase; decrease
b. decrease; decrease
d. decrease; increase
59. Which sediment load carries electrically charged ions?
a. bed load
c. suspended load
b. dissolved load
d. bank load
60. Which sediment load is likely to move the least, in between periods of flood?
a. bed load
c. suspended load
b. dissolved load
d. bank load
61. Which has greater competence?
a. a small, steep mountain stream
b. a broad, slow-flowing river
62. Which has greater capacity?
a. a small, steep mountain stream
b. a broad, slow-flowing river
63. All else being equal, water will flow faster in a stream with ____________.
a. well-developed meanders
b. a straight channel
64. The slope of a stream surface measured between two points along its course is the ____________.
a. base level
c. gradient
b. floodplain
d. thalweg
65. The stream gradient of most rivers ____________.
a. is greater near the source than near the mouth
b. is greater near the mouth than near the source
c. does not change significantly as the river flows downstream
d. is greater for a meandering stream than for any other type
66. All else being equal, water will flow slower in a stream that has a ____________.
a. steep stream gradient
b. gentle stream gradient
67. Ultimately, the base level of a stream valley can be no lower than ____________.
a. the average elevation of the continent on which it is found
b. the level of water in the world’s oceans
c. the average depths of the world’s ocean basins
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68. Moving downstream, the flow of a stream or river usually becomes less ____________.
a. turbulent
c. meandering
b. saline
d. Laminar
69. Within a meander, where is sediment most likely to be deposited?
a. on the outer bank (cut bank) of the meander
b. on the inner bank (point bar) of the meander
c. uniformly to either side of the meander
70. The flat-lying area surrounding a river channel is termed the ____________.
a. base level
c. stream gradient
b. floodplain
d. thalweg
71. The shape of a delta is primarily determined by ____________.
a. the shape of the river channel near the mouth
b. the average grain size of the suspended and bed loads
c. whether river currents, wave-driven currents, or tidal currents are locally predominant
d. the type of rock that is weathering at outcrop near the headwaters of the river
72. A meander that is cut off to become completely isolated from the main channel, but that retains water, is a(n)
_______.
a. meander neck
c. oxbow lake
b. cut bank
d. abandoned meander
73. The deltas of all major rivers consist of multiple radiating lobes of sediment in a “bird’s foot”
configuration, similar to the Mississippi River Delta.
a. true
b. false
74. At a delta, ____________.
a. stream gradient decreases
b. a single channel breaks into multiple, radiating distributary channels
c. a and b are both correct.
d. None of the above is correct.
75. Pirate streams ____________.
a. consist of a series of intertwined channels that are overloaded with sediment
b. have flowing water either episodically or during a portion of the year
c. have a channel that is highly sinuous (curvy)
d. have increased their drainage areas
76. If a stream cuts through flat-lying sediments to reach an anticline produced in an ancient orogenic
event, the course of the stream will likely be affected.
a. true
b. false
77. All flooding events occur so rapidly that there is no time to alert people in harm’s way.
a. true
b. false
78. A 100-year flood is less catastrophic than a 50-year flood.
a. true
b. false
79. If a 50-year flood occurs on the Mississippi River in 2005, what is the probability that a flood of the same
magnitude will occur in 2006?
a. Zero
c. 2%
b. 1%
d. 50%
80. In areas that have become urbanized, the percolation of rainwaters tends to decrease and the speed at
which rainwaters flow into streams and rivers tends to increase. Which of the following would be good
ways to counteract this effect?
a. Dig drainage ditches to the streams and rivers, for rainwaters to flow through quickly.
b. Dig out shallow areas for rainwater runoff to collect into, to allow slow percolation into soils.
c. Increase the carrying capacity of storm water sewer systems.
d. Both A and C
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81. Volcanic bombs _____.
A.
B.
C.
D.
are pyroclastic blocks that acquire aerodynamic shapes during flight out of the volcanic vent
are explosive bodies of lava with high volatile content
are cinders that explode upon impact with the ground
are used by geologists to set off small eruptions in volcanoes that are deemed potentially dangerous.
82. If a 10-year flood occurs on the Mississippi River in 2003, what is the probability that a flood of at the
same magnitude will occur in 2004?
A. zero
B. 1%
C. 10%
D. 50%
83. The water table typically lies above the bottom of a stream in a _____ climate.
A. hot
B. cold
C. moist
D. dry
84. Which has greater capacity, a small mountain stream, or the Mississippi River?
A. the mountain stream
B. the Mississippi
85. A stream begins at an elevation of 200 meters and flows a distance of 400 kilometers to the ocean? What
is the average gradient?
a. 2m/km
b. 2km/m
c. 0.5m/km d. 0.5km/in
86. The product of the average flow velocity and the area (width x depth) of the channel cross section.
a. Runoff gradient b. Stream discharge c. Hydrocapacity d. Stream load factor
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