GEOL 1403 - Exam IV

Total Flash Cards » 162
 
1. 

Plates are moving apart from one another

(Trasform, Divergent, or Convergent)

 

Divergent

 
2. 

Plates are sliding past one another horizontally

(Trasform, Divergent, or Convergent)

 

Transform (Oblique)

 
3. 

This boundary is normally devoid of volcanism

(Trasform, Divergent, or Convergent)

 

Transform (Oblique)

 
4. 

Where lithosphere is sinking into the mantle

(Trasform, Divergent, or Convergent)

 

Convergent

 
5. 

Characterized by basaltic volcanism and seafloor spreading

(Trasform, Divergent, or Convergent)

 

Divergent

 
6. 

Characterized by arcs of stratovolcanoes and deep-ocean trenches

(Trasform, Divergent, or Convergent)

 

Convergent

 
7. 

The Mid-Atlantic Ridge

(Trasform, Divergent, or Convergent)

 

Divergent

 
8. 

Where subduction zones occur

(Trasform, Divergent, or Convergent)

 

Convergent

 
9. 

The San Andreas fault

(Trasform, Divergent, or Convergent)

 

Transform (Oblique)

 
10. 

The west coast of South America

(Trasform, Divergent, or Convergent)

 

Convergent

 
11. 

The oldest rocks on the seafloor are much younger than the oldest rocks on the continents.

(True or False)

 

True

 
12. 

Earth's radius and surface area are slowly increasing to accommodate the new oceanic creust being formed at mid-ocean ridges.

(True or False)

 

False

 
13. 

Hawaii is the oldest island of the Hawaiian Island chain.

(True or False)

 

False

 
14. 

The oldest rocks of the oceanic crust are found in deep ocean trenches far away from active mid-ocean ridges.

(True or False)

 

True

 
15. 

As the South Atlantic basin widens by seafloor spreading, Africa and South America are moving closer together.

(True or False)

 

False

 
16. 

In general, rocks of the continental crust are less dense than rocks of the oceanic crust.

(True or False)

 

True

 
17. 

During various times in the geologic past, the polarity of Earth's magnetic field has been reversed.

(True or False)

 

True

 
18. 

The rate of seafloor spreading is, on the average, about one meter per year.

(True or False)

 

False

 
19. 

Wegener's continental drift hypothesis was weakened because a viable mechanism for moving the continents was lacking.

(True or False)

 

True

 
20. 

Seafloor spreading rates can be estimated if the geologic ages of the magnetic field reversals are independently known.

(True or False)

 

True

 
21. 

The volcanoes of Hawaii are localized above a deep mantle hot spot; they are not part of the East Pacific oceanic ridge.

(True or False)

 

True

 
22. 

S-waves can travel through solid and liquid media.

(True or False)

 

False

 
23. 

The time between the first P-wave and S-wave arrivals is a measure of the distance from a receiving station to the epicenter of the earthquake.

(True or False)

 

True

 
24. 

Earthquakes result from the sudden release of elastic strain energy previously stored in rocks surrounding a zone of fault movement.

(True or False)

 

True

 
25. 

Tsunamis are caused by sudden displacement of large volumes of seawater.

(True or False)

 

True

 
26. 

The epicenter of an earthquake is on the surface of the Earth directly above the focus.

(True or False)

 

True

 
27. 

Unconsolidated, water-saturated soils or sediments provide good foundation materials for buildings and other structures.

(True or False)

 

False

 
28. 

Continental crust is generally thicker than oceanic crust.

(True or False)

 

True

 
29. 

The crust and mantle are solids; the inner core is thought to be solid.

(True or False)

 

True

 
30. 

The Earth's magnetic field originates by...

 

... weak elctrical currents associated with fluid motions in the outer core.

 
31. 

When an earthquake occurs, energy radiates in all directions from its source. The source is also referred to as the...

 

... focus.

 
32. 

How do S- and P- waves differ in behavior?

 

S-waves travel through solids, and P-waves travel through liquids.

 
33. 

__________ have the highest velocities.

 

Primary waves

 
34. 

What is the nature of Tsunamis?

 

Tsunamis occur in the open ocean, wavelengths are many miles or kilometers and wave heights are only a few feet.

 
35. 

The amount of destruction caused by earthquake vibrations is affected by...

 

1) design of structures, 2) intensity and duration of the vibrations, and 3) nature of the surface material.

 
36. 

On a typical seismogram, __________ will show the highest amplitudes.

 

surface waves

 
37. 

The __________ magnitude scale is a measure of the energy released. It does not directly measure the extent of building damage.

 

Richter

 
38. 

The instrument that records earthquake events is termed a __________.

 

seismograph

 
39. 

__________ is the maximum possible damage designation on the Mercalli scale.

 

XII

 
40. 

The position on Earth's surface directly above the earthquake source is called the __________.

 

epicenter

 
41. 

The mechanism by which rocks store and eventually release energy in the form of an earthquake is termed __________.

 

elastic rebound

 
42. 

Overall, this type of seismic wave is the most destructive.

 

surface wave

 
43. 

Approximately how much more energy is released in a 6.5 Richter magnitude earthquake than in one with a magnitude 5.5?

 

30 times

 
44. 

P-waves...

 

... are faster than S-waves and surface waves.

 
45. 

The Mercalli Scale is a scale from ...

 

... I to XII that rates the structural damage due to an earthquake.

 
46. 

The distance between a seismological recording station and the earthquake source is determined from the ...

 

... arrival times of P- and S-waves.

 
47. 

The Richter magnitude of an earthquake is determined from the ...

 

... arrival time of P- and S- waves.

 
48. 

Which one of the following best characterizes tsunamis?

 

They have relatively small amplitudes compared to their very long wavelengths.

 
49. 

The __________ earthquake was accompanied by extensive fire damage.

 

San Franciso, 1906

 
50. 

__________ refers to the tendency for a foundation material to lose its internal cohesion and fail mechanically during earthquake shaking.

 

Liquefaction

 
51. 

The record of an earthquake obtained from a seismic instrument is a __________.

 

seismogram

 
52. 

Most of our knowledge about Earth's interior comes from...

 

... seismic waves.

 
53. 

Which one of the following statments about the crust is NOT true?

 

Oceanic crust is enriched in potassuim, sodium, and silicon.

 
54. 

The dense core of Earth is thought to consist predominantly of __________.

 

iron

 
55. 

The lithosphere is defined as ...

 

... a rigid layer of crustal and mantle material.

 
56. 

The average composition of the oceanic crust is thought to approximate that of __________.

 

basalt

 
57. 

The average composition of the continental crust most closely approximates that of __________.

 

granite

 
58. 

Tsunamis are caused by sudden displacement of large volumes of seawater.

(True or False)

 

True

 
59. 

The Richter earthquake magnitude scale is based on the total amount of energy released by the earthquake.

(True or False)

 

True

 
60. 

The epicenter of an earthquake is on the surface of the Earth directly above the focus.

(True or False)

 

True

 
61. 

Unconsolidated, water-saturated soils or sediments provide good foundation materials for buildings and other structures.

(True or False)

 

False

 
62. 

Oceanic crust is mainly basaltic in composition; the mantle is more like the igneous rock peridotite in chemical composition.

(True or False)

 

True

 
63. 

Continental crust is generally thicker than oceanic crust.

(True or False)

 

True

 
64. 

The crust and mantle are solids; the inner core is thought to be solid.

(True or False)

 

True

 
65. 

The mantle is composed mainly of metallic iron with small amounts of magnesium silicate minerals.

(True or False)

 

False

 
66. 

Earthquakes result from the sudden release of elastic strain energy previously stored in rocks surrounding a zone of fault movement.

(True or False)

 

True

 
67. 

__________ was an ancient reptile that lived in South America and Africa during the late Paleozoic.

 

Mesosaurus

 
68. 

In the early part of the 20th century, __________ argued forcefully for continental drift.

 

Alfred Wegener

 
69. 

The former late Paleozoic super continent is known as __________.

 

Pangaea

 
70. 

Today, __________ is in about the same geographic position as during late Paleiozoic time.

 

Antarctica

 
71. 

Pull-apart rift zones are generally associated with a __________ plate boundary.

 

Divergent

 
72. 

The temperature below which a magnetic material can retain a permanent magnetization is called the __________.

 

Curie point

 
73. 

A very long-lived magma source located deep in the mantle is called a __________.

 

hot spot

 
74. 

Linear, magnetic patterns associated with mid-ocean ridges are confitured as __________.

 

normal and reversed magnetized strips roughly parallel to the ridge

 
75. 

The __________ is a logical evolutionary analog of the African Rift Valleys ten million years from now.

 

Red Sea

 
76. 

A typical rate of seafloor spreading in the Atlantic Ocean is __________.

 

2 centimeters per year

 
77. 

The continental drift hypothesis was rejected primarily because Alfred Wegener could not __________.

 

identify a mechanism capable of moving continents

 
78. 

All of the following are evidence supporting the theory of plate tectonics except for __________.

 

changes in the Moon's orbit due to shifting plates

 
79. 

__________ was never proposed as evidence supporting the existence of Pangaea.

 

Similar fossils on different continents

 
80. 

Which one of the following most accurately describes the volcanoes of the Hawaiian Islands?

 

shield volcanoes fed by a long-lived hot spot below the Pacific lithospheric plate

 
81. 

Which of the following statements apply to the asthenosphere, but not the lithosphere?

 

zone in the upper mantle that deforms by plastic flowage

 
82. 

New oceanic crust and lithosphere are formed at ...

 

divergent boundaries by submaring eruptions and intrusions of basaltic magma.

 
83. 

Cooler, older, oceanic lithosphere sinks into the mantle at ...

 

subduction zones along convergent plate boundaries.

 
84. 

Deep ocean trenches are surficial evidence for...

 

sinding of oceanic lithosphere into the mantle at a subduction zone.

 
85. 

A transform plate boundary is characterized by ...

 

a deep, vertical fault along which two plates slide past one another in opposite directions.

 
86. 

Which one of the following is an important fundamental assumption underlying the plate tectonic theory?

 

Earth's diameter has been essentially constant over time.

 
87. 

The modern-day Red Sea is explained by plate tectonics theory because it is ...

 

a rift zone that may eventually open into a major ocean if Arabia and Africa continue to separate.

 
88. 

Mount St. Helens and the other Cascade volcanoes are ...

 

young, active stratovolcanoes built on a continental margin above a sinking slab of oceanic lithosphere.

 
89. 

The volcanoes and deep calleys of east Africa are related to a ...

 

continental rift along which parts of the African continent are beginning to slowly separate.

 
90. 

The Aleutian Islands occur at a ...

 

convergent boundary on a volcanic arc above a northward-subducting Pacific plate.

 
91. 

__________ most effectively outline the edges of the lithosperic plates.

 

Lines of earthquake epicenters

 
92. 

Deep-oceanic trenches are most abundant around the rim of the __________ ocean basin.

 

Pacific

 
93. 

Where would you drill to recover samples of the oldest basalts of the oceanic crust, which are Jurassic in age?

 

Oceanic side of the Aleutian trench

 
94. 

__________ first related the symmetrical magnetic patterns in seafloor basalts to seafloor spreading at a mid-ocean ridge.

 

Vine and Matthews

 
95. 

Early results of the Deep Sea Drilling Project clearly justified the conclusion that....

 

the ocean basins are relatively young; most ocean basin rocks and sediments are Cretaceous or younger in age.

 
96. 

Plates are moving apart from one another

(Convergent, Transform, or Divergent)

 

Divergent

 
97. 

Plates are sliding past one another horizontally

(Convergent, Transform, or Divergent)

 

Transform

 
98. 

This boundary is normally devoid of volcanism

(Convergent, Transform, or Divergent)

 

Transform

 
99. 

Where lithosphere is sinking into the mantle

(Convergent, Transform, or Divergent)

 

Convergent

 
100. 

Characterized by basaltic volcanism and seafloor spreading

(Convergent, Transform, or Divergent)

 

Divergent

 
101. 

Characterized by arcs of stratovolcanoes and deep-ocean trenches

(Convergent, Transform, or Divergent)

 

Convergent

 
102. 

The Mid-Atlantic Ridge

(Convergent, Transform, or Divergent)

 

Divergent

 
103. 

Where subduction zones occur

(Convergent, Transform, or Divergent)

 

Convergent

 
104. 

The San Andreas fault

(Convergent, Transform, or Divergent)

 

Transform

 
105. 

The west coast of South America

(Convergent, Transform, or Divergent)

 

Convergent

 
106. 

Water depths and seafloor topography are now routinely determined by ...

 

ship-mounted echo sounders.

 
107. 

Geologically, __________ are actually submerged parts of the continents.

 

continental shelves

 
108. 

The __________ lies at the base of the continental slope.

 

continental rise

 
109. 

Submarine canyons found on the continental slope and rise are believed to have been created by __________.

 

Turbidity currents

 
110. 

Which one of the following would most likely be covered with thick turbidite layers?

 

Deep-sea fan at the base of a continental slope

 
111. 

__________ sediments represent weathered rock and mineral particles eroded mainly from land areas.

 

Terrigenous

 
112. 

Seamouts ...

 

are volcanoes that form on the ocean floor.

 
113. 

"Black smokers" are associated with ...

 

ALL OF THESE!!!:

A) oceanic ridges

B) metal-rich sulfide deposits

C) hot water

 
114. 

Which one of the following is not connected in any way with submarine, hot spring vents?

 

Thick turbidites on the continental rise

 
115. 

__________ are not associated with a mid-ocean ridge.

 

Deep-ocean trenches

 
116. 

Where in the oceans are biological communities thriving without sunlight?

 

around seafloor, hot spring vents

 
117. 

Graded bedding is ...

 

an upward decrease in clastic particle size within a single sediment layer.

 
118. 

Calcareous ooze is composed of __________ sediment.

 

biogenous

 
119. 

Manganese nodules represent __________ sediment on the seafloor.

 

hydrogenous

 
120. 

Geologically, what is the best way to explain the thousands of feet of coral limestone beneath most atolls?

 

The eroded volcano slowly sank as sea level remained steady or rose gradually

 
121. 

Oceans cover approximately __________ of Earth's surface area?

 

70%

 
122. 

Manganese nodule

(Biogenous, Terrigenous, or Hydrogenous)

 

Hydrogenous

 
123. 

Calcareous ooze

(Biogenous, Terrigenous, or Hydrogenous)

 

Biogenous

 
124. 

Quartz sand

(Biogenous, Terrigenous, or Hydrogenous)

 

Terrigenous

 
125. 

Diatom ooze

(Biogenous, Terrigenous, or Hydrogenous)

 

Biogenous

 
126. 

Turbidite deposits

(Biogenous, Terrigenous, or Hydrogenous)

 

Terrigenous

 
127. 

Abyssal plain clay

(Biogenous, Terrigenous, or Hydrogenous)

 

Terrigenous

 
128. 

An echo sounder operates by measuring the time required for a ...

 

sound pulse to travel from the ship to the seafloor and back.

 
129. 

__________ is a characteristic, internal structure exhibited by turbidite sediment layers.

 

Graded bedding

 
130. 

__________ correctly formulated a basic theory concerning the formation of atolls in the 1800s.

 

Charles Darwin

 
131. 

Submerged, flat-topped volcanoes that rise from the deep ocean floor are called __________.

 

Seamounts

 
132. 

Valleys that lead from the continental shelf into deeper waters are known as __________.

 

Submarine canyons

 
133. 

__________ continental margins typically exhibit wide, extensive, continental shelves.

 

Passive

 
134. 

A __________ is a volcanic mountain, built up from the seafloor, that never reached the sea surface.

 

Guyot

 
135. 

A low lying, coral limestone island with a central lagoon is called an __________.

 

Atoll

 
136. 

An __________ is the vast, relatively deep, flat, sediment-covered portion of the deep-ocean basin.

 

Abyssal Plain

 
137. 

A __________ marks the site where old, oceanic lithosphere begins its descent into a subduction zone.

 

Trench

 
138. 

CH. 17 - MAY NOT BE ON EXAM...

A __________ fault has little or no vertical movements of the two blocks.

 

strike slip

 
139. 

In a __________ fault, the hanging wall block moves up with respect to the footwall block.

 

reverse

 
140. 

In thrust faulting, ...

 

the crust is shortened and thickened.

 
141. 

Which one of the following stress situations result in folding or flat-lying, sedimentary strata?

 

horizontally directed; compressive stresses

 
142. 

A graben is characterized by ...

 

a hanging wall block that

 
143. 

The mountains and valleys of the Basin and Range Province of the western United States formed in response to ...

 

tensional stresses and normal-fault movements.

 
144. 

In a normal fault, ...

 

the hanging wall block above an inclined fault plane moves downward relative to the other block.

 
145. 

A transform fault is ...

 

a strike-slip fault that forms the boundary between tectonic plates.

 
146. 

Brittle deformation would be favored over plastic deformation in which of the following conditions?

 

Cooler temperatures

 
147. 

A thrust fault is best described as ...

 

a low-angle, reverse fault.

 
148. 

A horst is ...

 

an uplifted block bounded by two normal faults.

 
149. 

A syncline is ...

 

a fold in which the strata dip toward the axis.

 
150. 

An __________ is a thick accumulation of sediments and small, tectonic blocks formed of material scraped off a descending, lithospheric plate.

 

accretionary-wedge complex

 
151. 

The Black Hills of South Dakota are a good example of a __________.

 

dome

 
152. 

Large circular downwarped structures are called ___________.

 

basins

 
153. 

Which of the following combinations should favor folding rather than faulting?

 

High temperature and high confining pressure

 
154. 

Tensional forces normally cause which one of the following?

 

normal faults

 
155. 

The __________ in California is the boundary between the North American and Pacific plates.

 

San Andreas strike-slip fault

 
156. 

The Sierra Nevada, California and Teton, Wyoming ranges are examples of ...

 

fault blocks uplifted by late Tertiary to Quaternary normal faulting.

 
157. 

A good example of a present-day passive continental margin is the ...

 

east coast of North America.

 
158. 

The __________ are a geologically old mountain range folded and deformed during the Paleozoic.

 

Appalachians in the eastern United States

 
159. 

The term __________ refers specifically to geologic mountain building.

 

orogenesis

 
160. 

Which one of the following is an example of an isostatic movement?

 

Uplift of areas recently covered by thick, continental ice sheets.

 
161. 

Folded limestones that occur high in the Himalayas were originally deposited as sediments in a ...

 

marine basin between India and Eurasia.

 
162. 

The concept that rocks of the crust and upper mantle are floating in gravitational balance is known as __________.

 

isostasy.