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Foundations of Earth Science, 7e (Lutgens)
Chapter 2
Rocks: Materials of the Solid Earth
2.1 Multiple Choice
1)
An igneous rock that shows a vesicular texture ________.
A)
contains many small holes, like Swiss cheese
B)
must be extrusive
C)
must be fine grained
D)
all of the above
Answer: D
Diff:
1
LO/Section: 2.2
Bloom's
Taxonomy: Comprehension
2)
An igneous rock that cools rapidly is likely to have ________ crystals.
A)
small
B)
medium-sized
C)
large
D)
pink
Answer: A
Diff:
1
LO/Section: 8.2
Bloom's
Taxonomy: Knowledge
3)
Examine
the rock sample here. Did it form at the surface or below the surface, and how
do you know?
A)
It formed at the surface, because of its color (composition).
B)
It formed at the surface, because of its texture (grain size).
C)
It formed below the surface, because of its color (composition).
D)
It formed below the surface, because of its texture (grain size).
Answer: B
Diff:
2
LO/Section: 2.2
Bloom's
Taxonomy: Analysis
4)
Which one of the following is an igneous rock?
A)
limestone
B)
rhyolite
C)
slate
D)
quartz
Answer: B
Diff:
1
LO/Section: 2.2
Bloom's
Taxonomy: Knowledge
5)
Which one of the following is a sedimentary rock?
A)
limestone
B)
rhyolite
C)
slate
D)
quartz
Answer: A
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Knowledge
6)
Which one of the following is a metamorphic rock?
A)
limestone
B)
rhyolite
C)
slate
D)
quartz
Answer: C
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Knowledge
7)
Rocks that contain crystals that are roughly equal in size and can be
identified with the unaided eye are said to exhibit a ________ texture.
A)
fine-grained
B)
coarse-grained
C)
glassy
D)
porphyritic
Answer: B
Diff:
1
LO/Section: 2.2
Bloom's
Taxonomy: Knowledge
8)
Magma that might have cooled slowly to produce a diorite is instead erupted at
Earth's surface. It would chill rapidly and produce a(n) ________.
A)
rhyolite
B)
andesite
C)
basalt
D)
granite
Answer: B
Diff:
2
LO/Section: 2.2
Bloom's
Taxonomy: Application
9)
Which igneous texture is characterized by two distinctively different crystal
sizes?
A)
fine-grained
B)
coarse-grained
C)
glassy
D)
porphyritic
Answer: D
Diff:
1
LO/Section: 2.2
Bloom's
Taxonomy: Knowledge
10)
Granite is ________.
A)
what countertops are made of
B)
coarse-grained and dominated by quartz and feldspar crystals
C)
coarse-grained and dominated by olivine, pyroxene and plagioclase feldspar
crystals
D)
fine-grained and dominated by quartz and feldspar crystals
Answer: B
Diff:
1
LO/Section: 2.2
Bloom's
Taxonomy: Comprehension
11)
To transform an igneous rock into a sedimentary rock, which of the following
processes must take place?
A)
melting and re-cooling, followed by crystallization
B)
chemical reactions under conditions of elevated temperature or pressure
C)
weathering, transport, deposition, and lithification
D)
impact by a meteorite
Answer: C
Diff:
1
LO/Section: 2.1
Bloom's
Taxonomy: Comprehension
12)
In general,
which of the statements below best describe what happens in terms of
composition as crystallization proceeds down the Bowen's reaction series (shown
in the figure)?
A)
The early-formed silicates are enriched in iron and magnesium, resulting in
such rocks as andesite and granite. As crystallization proceeds, the
later-formed silicates are enriched in sodium, potassium, and silicon,
resulting in peridotite and basalt.
B)
The early-formed carbonates are enriched in calcium and carbonate, resulting in
such rocks as limestone. As crystallization proceeds, the later-formed
carbonates are enriched in fossils, resulting in fossiliferous limestone and
coquina.
C)
The early-formed silicates are enriched in iron and magnesium, resulting in
such rocks as peridotite and basalt. As crystallization proceeds, the
later-formed silicates are enriched in sodium, potassium, and silicon,
resulting in andesite and granite.
D)
The early-formed silicates are enriched in sodium, potassium, and silicon,
resulting in such rocks as peridotite and basalt. As crystallization proceeds,
the later-formed silicates are enriched in iron and magnesium, resulting in
andesite and granite.
Answer: C
Diff:
1
LO/Section: 2.2
Bloom's
Taxonomy: Comprehension
13)
Consult
the image that depicts Bowen's reaction series. What can be said of the
temperature at which a granite crystallizes?
A)
Granite crystallizes at temperatures of about 750° C.
B)
Granite crystallizes at temperatures of about 900° C.
C)
Granite crystallizes at temperatures of about 1200° C.
D)
Nothing can be deduced from this chart about the crystallization temperature of
any igneous rock.
Answer: A
Diff:
2
LO/Section: 2.2
Bloom's
Taxonomy: Analysis
14)
Chemical weathering would be most effective ________.
A)
in a warm, wet climate
B)
in a cold, dry climate
C)
in a warm, dry climate
D)
deep beneath a mountain range
Answer: A
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Comprehension
15)
A crystal of potassium feldspar (KAlSi3O8) will produce a variety of weathering
products after it is weathered. Which of the following is NOT a product that
results from the weathering of potassium feldspar?
A)
silica
B)
potassium ions
C)
clay minerals
D)
iron oxides
Answer: D
Diff:
2
LO/Section: 2.3
Bloom's
Taxonomy: Analysis
16)
Three of the following statements about mechanical weathering are true. One is
false. Which statement is incorrect?
A)
Mechanical weathering does not affect metamorphic rocks.
B)
Mechanical weathering produces smaller pieces.
C)
Mechanical weathering does not change the rock's mineral composition.
D)
Mechanical weathering adds to the effectiveness of chemical weathering.
Answer: A
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Comprehension
17)
What
form of physical weathering is shown in this image?
A)
frost wedging
B)
sheeting
C)
root wedging
D)
hydrolysis
Answer: C
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Comprehension
18)
Which kind of rocks may contain fossils?
A)
igneous
B)
sedimentary
C)
metamorphic
D)
minerals
Answer: B
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Knowledge
19)
Most rock outcrops (about 75% of the total) are ________.
A)
igneous
B)
sedimentary
C)
metamorphic
D)
fossil-bearing
Answer: B
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Knowledge
20)
Detrital sedimentary rocks are classified and named principally on the basis of
________.
A)
grain size
B)
location
C)
rock color
D)
composition
Answer: A
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Comprehension
21)
Which rock type is most likely to have been deposited in a high- energy
environment (such as a very turbulent stream)?
A)
conglomerate
B)
shale
C)
chert
D)
microcrystalline limestone
Answer: A
Diff:
2
LO/Section: 2.4
Bloom's
Taxonomy: Application
22)
The skeletal remains of plankton make up the sedimentary rock ________.
A)
flint
B)
breccia
C)
travertine
D)
chalk
Answer: D
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Knowledge
23)
Which of the following rock types represents the highest grade of metamorphism?
A)
slate
B)
phyllite
C)
schist
D)
gneiss
Answer: D
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Knowledge
24)
Regional metamorphism occurs during ________.
A)
intrusion of magma
B)
mountain building
C)
sheeting of exposed plutons of granite
D)
chemical weathering of limestone in caves
Answer: B
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Comprehension
2.2 True-False
1)
This
photo shows a conglomerate.
Answer: FALSE
Diff:
2
LO/Section: 2.4
Bloom's
Taxonomy: Application
2)
All varieties of limestone are dominated by the mineral calcite.
Answer: TRUE
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Comprehension
3)
Frying an egg is a non-geological example of contact metamorphism.
Answer: TRUE
Diff:
2
LO/Section: 2.5
Bloom's
Taxonomy: Analysis
4)
In order to metamorphose, metamorphic rocks must melt.
Answer: FALSE
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Comprehension
5)
Confining pressure produces foliated metamorphic rocks.
Answer: FALSE
Diff:
2
LO/Section: 2.5
Bloom's
Taxonomy: Application
6)
The parent rock of marble is sandstone.
Answer: FALSE
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Comprehension
7)
Because of its rock cleavage, slate makes a better roofing material than rock
gypsum.
Answer: TRUE
Diff:
2
LO/Section: 2.5
Bloom's
Taxonomy: Analysis
8)
Coal is a sedimentary rock that is made of organic matter.
Answer: TRUE
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Comprehension
9)
Mud cracks and ripple marks are common features of igneous rocks.
Answer: FALSE
Diff:
3
LO/Section: 2.4, 2.2
Bloom's
Taxonomy: Synthesis
10)
Compaction and cementation are the most common forms of lithification.
Answer: TRUE
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Comprehension
11)
All metamorphic rocks began as other rocks ("parent rocks") that were
then subjected to elevated temperatures or pressures.
Answer: TRUE
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Comprehension
12)
A large proportion of feldspar sets arkose apart from regular sandstone.
Answer: TRUE
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Knowledge
13)
Given the right conditions any kind of rock can be transformed into any other
kind of rock.
Answer: TRUE
Diff:
1
LO/Section: 2.1
Bloom's
Taxonomy: Comprehension
14)
Rusting is an example of mechanical weathering.
Answer: FALSE
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Knowledge
15)
Slate is a common nonfoliated metamorphic rock.
Answer: FALSE
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Comprehension
2.3 Fill in the Blank
1)
Granite and gabbro have a similar ________.
Answer: texture
Diff:
1
LO/Section: 2.2
Bloom's
Taxonomy: Comprehension
2)
Obsidian is characterized by its ________ texture.
Answer: glassy
Diff:
1
LO/Section: 2.2
Bloom's
Taxonomy: Knowledge
3)
________ is formed when carbon dioxide dissolves in rainwater, and this mildly
reactive substance aids chemical weathering.
Answer: carbonic acid
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Knowledge
4)
Before it can be sedimentary rock, sediment must be produced (weathered from
pre-existing rocks), transported, deposited, and ________.
Answer: lithified
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Comprehension
5)
In contact metamorphism, ________ is the dominant agent of change.
Answer: heat
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Knowledge
6)
The rock ________ is a description of how one rock may be transformed into
another kind of rock through various internal and external processes.
Answer: cycle
Diff:
1
LO/Section:
2.1
Bloom's
Taxonomy: Knowledge
7)
A detrital sedimentary rock dominated by sand is a(n) ________.
Answer: sandstone
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Knowledge
8)
Chemical sedimentary rocks form when ________ in solution precipitate out mineral
matter.
Answer: ions
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Comprehension
9)
Layers in sedimentary rocks are called ________.
Answer: beds
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Comprehension
10)
The difference between a breccia and a conglomerate is ________.
Answer: conglomerates have rounded grains; breccias
have angular grains
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Comprehension
11)
Rock salt and rock gypsum are examples of ________ sedimentary rocks.
Answer: chemical
Diff:
1
LO/Section: 2.4
Bloom's
Taxonomy: Knowledge
12)
When a granite pluton (formed deep underground) is uplifted and exposed at the
surface, it may undergo sheeting to form a(n) ________.
Answer: exfoliation dome
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Knowledge
13)
Heat, confining pressure, differential stress, and ________ are four agents
that drive metamorphic reactions.
Answer: chemically active fluids
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Knowledge
14)
Confining pressure results from ________ of rocks.
Answer: burial
Diff:
1
LO/Section: 2.5
Bloom's
Taxonomy: Comprehension
15)
The reason we see so much mud and sand along the shore of the land is that clay
minerals and quartz are ________ at Earth's surface.
Answer: stable
Diff:
2
LO/Section: 2.3
Bloom's
Taxonomy: Application
2.4 Matching
Match the items in the first column with the correct
descriptions in the second column.
A)
Reactions that take place, often facilitated by water, to new produce products,
mainly clay minerals, which are stable at Earth's surface.
B)
The reaction of a substance (often a metal ion) with oxygen. Rust is an
example.
C)
The breaking of rock into smaller pieces.
D)
When water freezes, it expands in volume. Water-filled cracks can be enlarged
when this new ice exerts outward pressure on the walls of the fracture.
E)
The expansion of rocks that formed under high confining pressure, once they are
uplifted and exposed at Earth's surface producing fractures that are broadly
curved and parallel to the land surface.
F)
Pressure that is unequal in different directions, such as results from the
convergence of tectonic plates (mountain-building)
G)
A substance that forms when carbon dioxide in the air combines with water. It
is an important agent of chemical weathering.
H)
Pressure that is equal in every direction, such as results from the burial of
sediments
1)
Differential stress
Diff:
1
LO/Section:
2.3
Bloom's
Taxonomy: Comprehension
2)
Confining pressure
Diff:
1
LO/Section:
2.3
Bloom's
Taxonomy: Comprehension
3)
Frost wedging
Diff:
1
LO/Section:
2.3
Bloom's
Taxonomy: Comprehension
4)
Sheeting
Diff:
1
LO/Section:
2.3
Bloom's
Taxonomy: Comprehension
5)
Oxidation
Diff:
1
LO/Section:
2.3
Bloom's
Taxonomy: Comprehension
6)
Carbonic acid
Diff:
1
LO/Section:
2.3
Bloom's
Taxonomy: Comprehension
7)
Mechanical weathering
Diff:
1
LO/Section:
2.3
Bloom's
Taxonomy: Comprehension
8)
Chemical weathering
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Comprehension
Answers:
1) F 2) H 3) D 4) E 5) B 6) G 7) C 8) A
2.5 Labeling
1)
Label each process or set of processes (lettered arrows) and Earth materials
(numbered boxes).
Answer:
Diff:
1
LO/Section: 2.1
Bloom's
Taxonomy: Comprehension
2.6 Essay
Answer the questions in complete sentences. Be
complete but concise.
1)
Discuss how the following variables influence the rate of weathering: Mineral
content, climate, and topography.
Answer: More stable minerals, like quartz, are more
resistant to weathering. Minerals that are less stable (less at equilibrium at
Earth surface conditions) are less resistant to weathering; they fall apart
more rapidly. Hence a tombstone made of granite will last longer than a
tombstone made of marble … or worse, rock salt! Warmer, wetter climates
encourage weathering, as water helps facilitate chemical reactions like
dissolution, oxidation, and hydrolysis, and more heat means more energy to
drive those reactions. Steeper slopes are more likely to shed any sediment that
gets produced, meaning that physical weathering will dominate over chemical
weathering. Shallower slopes tend to see less movement of the sediment that
results from weathering, resulting in thick sections of "rotted"
(chemically weathered) bedrock.
Diff:
1
LO/Section: 2.3
Bloom's
Taxonomy: Comprehension
2)
Identify
each photo with a material name. Explain the processes which would have to
occur as each material is transformed (arrows) into other materials. Include a
plausible "next step" to replace the big question mark at the end.
Answer: Pebbles, a kind of sediment, could be
transformed into a conglomerate through the process of lithification. After
they were generated, transported (causing them to round), and deposited, the
pebbles would then either be compressed or cemented together to form the
sedimentary rock conglomerate. This conglomerate could be induced to melt with
application of sufficient heat, rendering it into magma. That magma could cool
and crystallize, producing the igneous rock granite. In terms of what happens
next, this granite might experience differential stress and be metamorphosed in
a mountain-building event to produce a gneiss. (Answers for this last part will
vary.)
Diff:
3
LO/Section: 2.1, 2.2, 2.3, 2.4
Bloom's
Taxonomy: Synthesis
3)
How
are the two main categories of weathering represented in this image that shows
human-made objects?
Answer: The broken glass bottles provide an example
of mechanical weathering: to make them, a single glass bottle would have to be
shattered into numerous shards of glass. Though many new pieces of glass
result, the substance itself (glass) has not been transformed into anything
new. In contrast, the rusty cans provide an example of chemical weathering: to
make them, an initial can would have to react with oxygen in the atmosphere (an
oxidation reaction facilitated by water) and a new substance (rust) would be
produced at the expense of the material that composed the original cans.
Diff:
3
LO/Section: 2.3
Bloom's
Taxonomy: Synthesis
2.7 Critical Thinking
1)
What is the source of energy that transforms igneous rocks into sedimentary
rocks? What is the source of energy that transforms sedimentary rocks into
metamorphic rocks? What is the source of energy that transforms metamorphic
rocks into igneous rocks? Are these sources of energy internal or external?
Explain.
Answer: Sedimentary result from external processes
including weathering, transport, and deposition. The energy to break down and
move sediment comes ultimately from the Sun. To get rocks to a place where they
can be weathered, energy from plate tectonics must also be involved. Igneous
rock are certainly related to internal heat and plate tectonics; Metamorphic
are also more internal-process related. A sedimentary rock that is going to be
transformed into an igneous rock by melting will most likely first metamorphose
as it warms up. So, metamorphic and igneous rocks form as a result of Earth's
internal energy, the same energy that drives plate tectonics. The surface
processes that generate, move, and dump sediments are ultimately driven by solar
energy.
Diff:
3
LO/Section: 2.1, 2.2, 2.3, 2.4, 2.5
Bloom's
Taxonomy: Synthesis
2)
Why would intrusive rocks chemically weather more quickly than extrusive rocks?
Why would mafic rocks chemically weather more easily than felsic rocks?
Answer: There are several reasons that intrusive
rocks would chemically weather more quickly than extrusive rocks. The place
they form is the first reason: by definition, extrusive igneous rocks form at
Earth's surface, which is also where weathering happens. For intrusive igneous
rocks to experience weathering at Earth's surface, they must first go through
an additional step: uplift sufficient to cause exposure. Second is the issue of
grain size. Minerals weather from the outside, in. Smaller mineral grains have
a greater amount of surface per unit of volume, while relatively coarse
crystals in plutons have less reactive surface area. Basaltic (mafic) rocks
have a greater proportion of dark silicate minerals, which are enriched in the
elements iron and magnesium, both of which are susceptible to oxidation. Felsic
rocks have a higher proportion of quartz, which is stable at Earth surface
conditions.
Diff:
3
LO/Section: 2.2, 2.3
Bloom's
Taxonomy: Synthesis
3)
Consider the history of a single crystal of quartz. Describe how could this
quartz grain could (a) form in a granite, (b) become incorporated into a
sandstone, and (c) be transformed into a quartzite? Explain the processes which
act on the quartz crystal and the transformations it experiences. Detail the
processes which would take place along each portion of this journey.
Answer: The quartz crystal would originally form from
magma, cooling deep in Earth's interior. Because it's part of an intrusion of
magma, it cools slowly, so there's plenty of time to grow a nice coarse quartz
crystal. It forms last among the minerals in the crystallizing magma, as
predicted in Bowen's reaction series. Because of the felsic composition and the
coarse grain size, the rock that this quartz (mineral) grain is part of would
be referred to as a granite. Once solidified, time goes by, and the granite is
uplifted towards the surface. When it gets to the surface, it is attacked by
chemical and mechanical weathering. Sheeting occurs, and carbonic acid in
rainwater helps to break down the quartz's neighboring feldspars. The few dark
silicate minerals in the granite are oxidized. One day, in a big storm, the
quartz crystal breaks free and is tumbled down a small stream along with a
bunch of clay minerals. The small stream feeds into a big river, and the quartz
grain eventually is transported to the ocean. There, it is deposited on a beach
full of similar sand-sized grains of quartz. Over geologic time, these sand
layers are buried and subjected to confining pressure, and they become
lithified to form a sandstone. A new intrusion of magma occurs nearby, and the
sandstone is "cooked" by its heat. The small quartz grains
recrystallize, fusing together and forming large, equidimensional grains that
are randomly oriented. It is now a quartzite, a metamorphic rock.
Diff:
3
LO/Section: 2.1, 2.2, 2.3, 2.4, 2.5
Bloom's
Taxonomy: Synthesis
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