Download Earth Systems 3209 - Heritage Collegiate

Earth Systems 3209
Test
Chapters 3 & 4 Solutions
Name _______________
Multiple Choice. Choose the best answer for the following multiple choice questions. Write
the UPPERCASE letter of the correct answer on the answer sheet on page 8. [21 marks]
1. Molten material found inside the earth is called ______ .
a) lava
b) plasma
c) magma
d) rock fluid
e) mineraloid
2. The process of igneous rock formation is called ______ .
a) weathering
b) lithification
c) foliation
d) decomposition
e) crystallization
3. Igneous rocks that contain the last minerals to crystallize from magma and consist mainly of
feldspars and quartz are said to have a ______ composition.
a) granitic
b) basaltic
c) lithic
d) gneissic
e) metamorphic
4. When large masses of magma solidify far below the surface, they form igneous rocks that
exhibit a ______ texture.
a) fine-grained
b) coarse-grained
c) fragmental
d) glassy
e) porphyritic
5. Why can two igneous rocks have the same minerals but different names?
a) They may have different colors
b) Names of igneous rocks are arbitrary
c) The rocks may be of different sizes
d) They may have different textures
e) They may have been found in different places
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6. Igneous rocks formed from magma that crystallized at depth are called ______ or intrusive
rocks.
a) plutonic
b) volcanic
c) foliated
d) metamorphic
e) porphyritic
7. Most of the earth's seismic activity, volcanism, and mountain building occur along ______ .
a) lines of magnetism
b) parallels of latitude
c) hot spots
d) plate boundaries
e) random trends
8. During oceanic-continental convergence, as the oceanic plate slides beneath the overriding
plate, a ________ is often produced adjacent to the zone of subduction.
a) deep-ocean terrace
b) transform fault
c) divergent boundary
d) deep-ocean ridge
e) deep-ocean trench
9. The chain of volcanic structures, extending from the Hawaiian Islands to Midway Island and
then continuing northward toward the Aleutian trench has formed over a(n) ________ as the
Pacific plate moved.
a) subduction zone
b) island arc
c) divergent boundary
d) hot spot
e) convergent boundary
10. Highly viscous magmas tend to impede the upward migration of expanding gases, which often
results in ________ eruptions.
a) relatively quiet
b) explosive
11. The most violent type of volcanic activity is associated with ______ .
a) cinder cones
b) composite cones
c) shield cones
d) sills
e) intermediate cones
12. Which one of the following is NOT a factor that determines the violence of a volcanic eruption?
a) temperature of the magma
b) size of the volcanic cone
c) the magma's composition
d) amount of dissolved gases in the magma
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13. The area of igneous activity commonly called the Ring of Fire surrounds the ______ .
a) Indian Ocean
b) Atlantic Ocean
c) Pacific Ocean
d) Coral Sea
e) Sea of Japan
14. A magma's viscosity is directly related to its ______ .
a) depth
b) volcanic cone
c) color
d) age
e) silica content
15. Pulverized rock, lava, and glass fragments produced from the vent of a volcano are known as
_____ .
a) nuee ardentes
b) pyroclastics
c) pahoehoes
d) sills
e) craters
16. Which type of volcano consists of interbedded strata of lavas and pyroclastic material?
a) cinder cone
b) intermediate cone
c) pyro-cone
d) composite cone
e) shield cone
17. Basaltic lava tends to be ________ fluid than granitic lava.
a) more
b) less
18. Eruptions of fluid basaltic lavas, such as those that occur in Hawaii, tend to be ______ .
a) relatively quiet
b) extremely violent
c) unpredictable
d) explosive
19. The type of volcano produced almost entirely of pyroclastic material is the ______ .
a) shield volcano
b) composite cone
c) batholith
d) cinder cone
e) pyro-cone
20. Which volcanoes are generally small and occur in groups?
a) composite cones
b) shield cones
c) intermediate cones
d) laccoliths
e) cinder cones
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21. Intraplate volcanism may be associated with the formation of ________ over rising plumes of
hot mantle material.
a) hot spots
b) subduction zones
c) volcanic necks
d) dikes
e) ocean ridges
True/False. For the following true/false questions, if a statement is not completely true, mark
it false. Place a T for true and F for False on the answer sheet on page 8. [20 marks]
1. The most common extrusive igneous rock is granite.
2. The rock cycle shows the relations among the three rock types, and is essentially an outline of
physical geology.
3. Granite is a classic example of an igneous rock that exhibits a coarse-grained texture.
4. Because magma's density is greater than the surrounding rocks, it works its way to the surface
over time spans from thousands to millions of years.
5. The process called weathering, whereby magma cools, solidifies, and forms igneous rocks, may
take place either beneath the earth's surface, or on the surface following a volcanic eruption.
6. Molten material found on the earth's surface is called magma.
7. The texture of an igneous rock is based in the size and arrangement of its interlocking crystals.
8. According to Bowen's reaction series, quartz is often the last mineral to crystallize from a melt.
9. Slow cooling of magma results in the formation of small mineral crystals.
10. Older portions of the sea floor are carried into the earth's core in regions where trenches occur in
the deep-ocean floor.
11. The "Ring of Fire" is an area of earthquake and volcanic activity that encircles the Pacific
Ocean basin.
12. Deep-ocean trenches are located adjacent to subduction zones.
13. Most of the earth's active volcanoes are near divergent plate margins.
14. The more viscous a material, the greater its resistance to flow.
15. The smallest volcanoes are composite cones.
16. The greatest volume of volcanic rock is produced along the oceanic ridge system.
17. Magmas that produce basaltic rocks contain more silica than those that form granitic rocks.
18. A magma's viscosity is directly related to its iron content.
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19. When subduction volcanism occurs in the ocean, a chain of volcanoes called an island arc is
produced.
20. The viscosity of magma, plus the quantity of dissolved gases and the ease with which they can
escape, determines the nature of volcanic eruptions.
Word Choice. Complete each of the following statements by selecting the correct response(s).
Write the correct response on the answer sheet on page 8. [21 marks]
1. The very first rocks to form on the earth's surface were [igneous/sedimentary/metamorphic].
2. Because a magma body is [less/more] dense than the surrounding rocks, it works its way
toward/away from] the surface over time spans of thousands to millions of years.
3. The molten minerals in magma are primarily members of the [carbonate/silicate/sulfide] group.
4. A rock that will effervesce with dilute hydrochloric acid most likely contains the mineral
[quartz/calcite/feldspar].
5. At convergent plate boundaries, oceanic lithosphere is being [created/consumed].
6. The region where one plate descends into the asthenosphere below another plate is called a
[rifting/subduction] zone.
7. At divergent plate boundaries, lithosphere is being [created/destroyed].
8. Hot spots are believed to be created by [converging plates/mantle plumes].
9. When spreading centers develop within a continent, valleys called [trenches/rifts] form.
10. The magma produced in a subduction zone often produces [oceanic ridges/volcanic arcs].
11. The greatest volume of volcanic material is produced along the [ocean trenches/oceanic ridge
system].
12. The magma of spreading center volcanism is produced primarily by the partial melting of
[continental crust/upper mantle rock/oceanic crust] and is mostly of [basaltic/granitic]
composition.
13. A volcanoes effect on climate, if any, would be caused by ash and [lava/gases] being ejected
into the [upper/lower] atmosphere.
14. [Increasing/Decreasing] the silica content of magma will increase its viscosity.
15. The smallest volcanic cones are typically [cinder/composite/shield] cones.
16. The most fluid magmas have a [basaltic/granitic] composition.
17. The most explosive volcanism is associated with [spreading center/subduction zone] volcanism
due to the relatively high [crystal/basalt/water] content of the associated magma.
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Written Questions: Answer all questions on this paper.
1. Explain how each zone of volcanic activity listed below is related to plate tectonics. [6 marks]
a) Pacific Ring of Fire
At convergent plate boundaries, slabs of ocean crust descend into the mantle, creating an
ocean trench. The ocean crust eventually melts and the less dense basaltic or andesitic
magma moves slowly upward toward the surface. The volcanoes produced lie in a linear
or slightly curved chain and are called continental volcanic arcs if they lie on land and
volcanic island arcs if they are formed under the ocean and rise above sea level. Both arcs
will lie roughly parallel to the ocean trench (see Figure 4.35 p. 120). Mount St. Helens is
part of a continental volcanic arc.
b) Mid-Ocean Ridges
When two tectonic plates move apart in the ocean, magma rises up into the rift valley
created and produces new seafloor on either side of the rift (seafloor spreading). Material
builds up on either side of the rift to create an ocean ridge. Iceland was formed when the
material on either side of the rift rose above sea level. When two plates move apart on a
continent, a similar process occurs. The greatest volume of volcanic rock is produced at
divergent plate boundaries.
c) Hot Spots
These volcanoes do not occur at the plate boundaries (intraplate volcanism). Volcanoes
are formed here because the mantle under the crust in this area is hotter than normal so
the material moves upward toward the crust and creates a mantle plume. When the
magma (basaltic or granitic) reaches the surface, a volcano called a hot spot is formed.
The islands of Hawaii are the result of hot spot volcanism.
2. In the table below, place a check mark to indicate which magma has the greater amount of each
characteristic. [3 marks]
Basaltic magma
Granitic magma
Silica Content
Viscosity


Melting Temperature

3. Describe the texture of both granite and basalt. Explain how the texture of each rock was
formed. [4 marks]
a) Granite:
Texture of Granite: course grained (phaneritic)
Reason: Molten rock called magma is insulated within Earth and loses its heat slowly to the
surrounding rock. This slow cooling allows the crystals within the magma to become relatively
large which forms a course texture
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b) Basalt:
Texture of Basalt: fined grained (aphanitic)
Reason: Molten rock called lave flows on or near the surface where it loses heat quickly to the
surrounding rock or air. This rapid cooling does not allow large crystals to form within the lava
and results in the formation of a fine grained texture.
4. Match the description to the corresponding term in the table below. [6 marks]
Texture
Description
A. Openings produced by escaping gases.
B. A texture characterized by two distinctly
different crystals.
C. Obsidian exhibits this texture.
D. Crystals are too small to be seen without a
microscope.
E. Coarse-grained, with crystals of roughly
equal size.
F. Exceptionally large crystals exceeding 1cm in
diameter.
__E__ Phaneritic
__D__ Aphanitic
__A__ Vescular
__B__ Porphyritic
__C__ Glassy
__F__ Pegmatitic
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Name _______________________
Multiple Choice:
1.
2.
3.
4.
5.
6.
7.
____C
____E
____A
____B
____D
____A
____D
8. ____E
9. ____D
10. ____B
11. ____B
12. ____B
13. ____C
14. ____E
15. ____B
16. ____D
17. ____A
18. ____A
19. ____D
20. ____E
21. ____A
8. ____T
9. ____F
10. ____F
11. ____T
12. ____T
13. ____F
14. ____T
15. ____F
16. ____T
17. ____F
18. ____F
19. ____T
20. ____T
True/False:
1.
2.
3.
4.
5.
6.
7.
____F
____T
____T
____F
____F
____F
____T
Word Choice:
1.
2.
3.
4.
5.
6.
7.
8.
9.
igneous
less toward
silicate
calcite
consumed
subduction
created
mantle plumes
rifts
10. volcanic arcs
11. ocean ridge system
12. upper mantle rock
basaltic
13. gases lower
14. increasing
15. cinder
16. basaltic
17. subduction zone water
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