Chapter 20 Rocks and Minerals
20.1 The Geosphere is Made Up of Rocks and Minerals
1) The two most abundant elements in Earth's crust are
A) silicates and carbonates.
B) silicon and oxygen.
C) oxygen and aluminum.
D) quartz and feldspar.
Answer: B
2) Based on its abundance in Earth's crust, most rocks contain a mineral composed of the
elements oxygen and
A) carbon.
B) silicon.
C) iron.
D) sulfur.
Answer: B
3) The three sources that brought young Earth to its melting point were
A) impact heating, convection heating, radiometric heating.
B) impact heating, gravitational contraction heating, radioactive decay heating.
C) impact heating, convection heating, radioactive decay heating.
D) collisional heating, contraction heating, radiometric heating.
Answer: B
4) Young Earth developed a layered structure under the influence of
A) impact heating and convection in its interior.
B) gravitational contraction and radioactive decay.
C) meteorite bombardment.
D) gravity and density segregation–the process of differentiation.
Answer: D
20.2 Minerals
1) Minerals are composed of
A) silicon compounds.
B) common types of rocks.
C) homogenous solids.
D) inorganic solids.
Answer: D
2) The protective shells that many sea organisms grow are not minerals because they
A) are not calcium carbonate.
B) are organic.
C) are made of ooze.
D) become compacted.
Answer: B
3) All minerals are
A) organic.
B) crystals.
C) crystalline solids.
D) synthetic.
Answer: C
4) What is the difference between a mineral and an element?
Answer: An element is a material consisting of only one type of atom. There are a few minerals
composed of a single element, but the majority are composed of a combination of elements. As
such, they are composed of more than one type of atom.
5) The majority of elements in the Periodic Table are metallic. Does this mean that most
minerals are metallic?
Answer: Although the different metallic elements combine and give us minerals, not all minerals
made up of these metallic elements make metallic minerals. Properties of the single elements are
very different from the properties of the compounds of elements. For example, the elements Na
and Cl combine to form the compound NaCl. Whereas elemental sodium is a soft silvery metal,
and elemental chlorine is a toxic yellow-green gas, when the two elements are combined they
form common table salt, NaCl (the mineral halite). Although composed of metallic elements,
halite is not considered to be a metallic mineral.
20.3 Mineral Properties
1) Most minerals can be identified by easily observable physical properties. In order of most
useful to least useful, the identifiable physical properties are
A) color, crystal form, hardness, cleavage, and density.
B) hardness, cleavage, density, crystal form, and color.
C) crystal form, color, hardness, cleavage, and density.
D) crystal form, hardness, cleavage, color, and density.
Answer: B
2) The mineral gold (Au) is very soft. Gold's softness can be attributed to
A) large, tightly packed atoms.
B) small, loosely bonded atoms.
C) large, loosely packed, and loosely bonded atoms.
D) large, closely packed, and strong bonded atoms.
Answer: C
3) Color is not a reliable means for mineral identification because
A) minerals come in a variety of colors, and chemical impurities in the mineral can affect color.
B) minerals can weather and change color.
C) a mineral's powdered color is different than its solid color.
D) there are so many colored minerals.
Answer: A
4) A mineral's hardness is dependent on the
A) strength of its chemical bonds.
B) mineral ionization.
C) size of its atoms, large atoms are harder than small atoms.
D) geometric arrangement of atoms.
Answer: A
5) The property of a mineral to break along planes of weakness is referred to as
A) cleavage.
B) hardness.
C) fracture.
D) bond strength.
Answer: A
6) Minerals that have strong bonds between flat crystal surfaces tend to
A) cleave more easily.
B) show poor cleavage.
C) show well developed cleavage.
D) have a well developed streak.
Answer: B
7) Minerals that have the same combination of elements but with different atomic arrangements
are called
A) polymorphs.
B) polygonal.
C) tetrahedra.
D) polymers.
Answer: A
8) Mohs scale is based on minerals that have different
A) cleavage directions.
B) colors.
C) hardnesses.
D) shapes.
Answer: C
9) Which of the following properties most clearly reflects the internal arrangement of atoms in a
crystalline material?
A) color
B) cleavage
C) luster
D) density
Answer: B
10) A mineral's hardness depends on the strength of its chemical bonds. Name and describe the
factors that influence hardness.
Answer: Factors that influence bond strength influence mineral hardness. Ionic charge: the
greater the charge, the greater the attraction between ions and hence, the stronger the bond. Ion
size: the smaller the ion/atom, the smaller the distance between ions, thus a greater attraction and
stronger bond. Ion packing: closely packed ions with their small distance between one another
have stronger attractions and stronger bonds. Stronger bonds yield harder minerals.
11) Cleavage is the tendency of a mineral to break along planes of weakness. What factors
determine these planes of weakness?
Answer: Crystal structure and chemical bond strength.
12) List the seven physical properties for identifying minerals.
Answer: The physical properties include crystal form, hardness, cleavage, luster, color, streak,
and density.
20.4 Classification of Rock-Forming Minerals
1) The most common rock forming minerals are composed of predominantly eight elements.
These minerals are the
A) silicates, carbonates, oxides, sulfides, and sulfates.
B) silicates, sulfides, and oxides.
C) silicons, borates, oxides, sulfides, and carbonates.
D) sulfates, oxides, and carbonates.
Answer: A
2) The most common mineral in Earth's crust is ________, and the second most common mineral
is ________.
A) quartz, feldspar
B) feldspar, quartz
C) silicate, carbonate
D) olivine, feldspar
Answer: B
3) Minerals are formed from the combination of different elements. The combination of different
metallic elements produces
A) metallic minerals.
B) metallic and nonmetallic minerals.
C) nonmetallic minerals.
D) polymorphs.
Answer: B
4) Most of the world's sand is composed of the minerals
A) feldspar and quartz.
B) silicon and oxygen.
C) quartz and muscovite.
D) silicon and aluminum.
Answer: A
5) Galena belongs to the class of minerals known as the
A) sulfides.
B) sulfates.
C) silicates.
D) carbonates.
Answer: A
6) Of the five rock-forming mineral groups-the silicates, carbonates, oxides, sulfides, and
sulfates-which two form economically important ores?
A) silicates and carbonates
B) carbonates and oxides
C) oxides and sulfides
D) sulfides and sulfates
Answer: C
7) By definition, an ore is a mineral rich in valuable metals. To be considered as an ore means
that the
A) metals can be economically extracted to yield a profit.
B) metals are extremely valuable.
C) deposit is very rich and abundant in valuable metals.
D) metallic minerals are very abundant.
Answer: A
8) A mineral deposit can be classified as an ore deposit when
A) valuable metals are present in the deposit.
B) valuable metals in the deposit can be mined at a profit.
C) it contains valuable fossil fuels.
D) it contains valuable gemstone quality minerals.
Answer: B
9) Our Earth has many resources, but they are not unlimited. In the case of abundant metals,
supply will most often meet demand. However, problems can occur when
A) there is a shortage of ores that can be mined at a reasonable cost.
B) high grade ores are depleted and low grade ores need to be mined.
C) transport and processing costs override economic feasibility.
D) all of the above.
Answer: D
10) A mineral that is not a silicate is
A) feldspar.
B) mica.
C) calcite.
D) quartz.
Answer: C
11) The silicates are the largest mineral group because silicon and oxygen are
A) the hardest elements on Earth's surface.
B) the two most abundant elements in Earth's crust.
C) found in the common mineral quartz.
Answer: B
12) Most of the world's sand is made up of which two minerals?
Answer: Feldspar, the most common and abundant mineral, and quartz, the second most
common mineral, make up most of the world's sand deposits.
13) What are the rock-forming mineral groups?
Answer: Silicates, carbonates, oxides, sulfides, and sulfates.
14) What is the major rock-forming mineral group? Give examples of minerals in this group.
Answer: Silicates are the most abundant mineral group in Earth's crust. Feldspars, quartz,
pyroxenes, amphiboles, and micas are examples of silicates.
15) What is an ore?
Answer: An ore is a mineral deposit that is rich enough in valuable metals that the metals can be
mined at a profit.
20.5 The Formation of Minerals
1) The melting point of silicate minerals is strongly dependent on the amount of silica it contains.
The first minerals to melt are those with
A) lowest melting point and lowest silica content.
B) lowest melting point and highest silica content.
C) lowest silica content and highest melting point.
D) highest silica content and highest melting point.
Answer: B
2) The process of crystallization acts to
A) enrich the molten magma in silica.
B) deplete the molten magma of silica.
C) enrich the crystallized minerals in silica.
D) none of the above.
Answer: A
3) The last minerals to crystallize from a cooling magma have the
A) lowest melting point and the highest percentage of silica.
B) lowest melting point and the lowest percentage of silica.
C) highest melting point and the highest percentage of silica.
D) highest melting point and the lowest percentage of silica.
Answer: A
4) Similar to the crystallization of silicate minerals, the crystallization of evaporite minerals
occurs in a step-by-step process. The evaporite minerals that are the most difficult to dissolve
A) precipitate last.
B) precipitate first followed by the minerals that dissolve more easily.
C) have the lowest solubility and are the last to precipitate.
D) have the highest solubility and are the first to precipitate.
Answer: B
5) Chemical sedimentary rocks are formed from
A) biochemical interactions.
B) carbonization.
C) the precipitation of minerals from a water solution.
D) evaporites.
Answer: C
6) The first minerals to crystallize are those with the
A) higher melting point.
B) lower melting point.
Answer: A
7) The last minerals to crystallize are those with the
A) higher melting point.
B) lower melting point.
Answer: B
8) Minerals are formed by the process of
A) crystallization.
B) magma differentiation.
C) silica enrichment.
D) partial melting.
Answer: A
9) The first minerals to crystallize from a cooling magma have a
A) high melting point and a low silica content.
B) low melting point and a high silica content.
C) high melting point and a high silica content.
D) low melting point and a low silica content.
Answer: A
10) The last minerals to crystallize from a cooling magma have a
A) high melting point and a low silica content.
B) low melting point and a high silica content.
C) high melting point and a high silica content.
D) low melting point and a low silica content.
Answer: B
11) As the process of crystallization continues (from molten liquid to solid crystal) the
composition of the molten liquid becomes
A) depleted in the minerals that have already crystallized.
B) enriched in the minerals that have already crystallized.
C) depleted in the minerals that have yet to crystallize.
D) enriched in the minerals that have yet to crystallize.
E) both A and D
F) both B and C
Answer: E
12) The precipitation of and crystallization of evaporite minerals is very similar to the
crystallization of minerals from a magma. The first evaporite minerals to precipitate (crystallize)
are those with the
A) lowest solubility.
B) highest melting point.
C) lowest silica content.
D) highest solubility.
Answer: A
13) For the crystallization of minerals from a magma, melting point determines which mineral
will form first. For evaporite minerals
A) solubility determines which mineral will form first.
B) salinity determines which mineral will form first.
C) melting point also determines which mineral will form first.
D) there is no single determinant. All evaporite minerals precipitate at the same time.
Answer: A
14) Silica has a relatively
A) low melting point.
B) high melting point.
Answer: A
15) Silica has a relatively
A) low percentage of silicon.
B) high percentage of silicon
Answer: B
16) Describe the process of crystallization.
Answer: Crystallization is the growth of a solid from a material whose atoms come together with
a specific chemical composition and crystalline arrangement. Beginning with the formation of a
single microscopic crystal, the crystal grows as more and more atoms bond to the crystal faces.
17) Describe two sources from which minerals can crystallize.
Answer: Minerals crystallize from 1) magma—molten rock from Earth's interior, and from 2)
water solutions—a) hydrothermal activity in the later stages of crystallization from a magma, and
b) precipitation of minerals from chemical sediments.
18) Which minerals are the first to crystallize in a cooling magma–minerals with a lower
percentage of silica or minerals with a higher percentage of silica?
Answer: Minerals with a lower percentage of silica.
19) Which mineral, quartz or feldspar, will crystallize first? Why?
Answer: Minerals with high silica content are the last to crystallize. Feldspar, with its lower
percentage of silica, will crystallize before quartz, which is 100% silica.
20) As the process of crystallization continues (from molten liquid to solid crystal), how does the
composition of the molten liquid change?
Answer: The molten liquid becomes enriched in the minerals that have already crystallized and
depleted in the minerals that have yet to crystallize.
21) In a cooling magma, which minerals are the first to crystallize?
Answer: Minerals with high melting point and low silica content are the first to crystallize.
22) In a cooling magma, which minerals are the last to crystallize?
Answer: Minerals with low melting point and high silica content are the last to crystallize.
23) The melting point of silicate minerals is strongly dependent on the amount of silica they
contain. Generally speaking, which minerals are the first to melt?
Answer: The first minerals to melt are those with the lowest melting point and highest silica
content.
20.6 Rock Types
1) A sedimentary rock can turn into an igneous rock by
A) compaction and cementation.
B) compaction.
C) melting and cooling.
D) weathering and lithification.
Answer: C
2) Rocks are grouped into three classes depending on how the rock was
A) formed.
B) located.
C) discovered.
D) shaped.
Answer: A
3) Igneous rock is formed from
A) crystallization of molten magma.
B) high temperatures and pressures.
C) solidified lava beneath the Earth's surface.
D) any of these
Answer: A
20.7 Igneous Rocks
1) The process of crystallization enriches a magma in
A) silica.
B) minerals that have low melting points.
C) silica and other minerals that have low melting points.
D) all of the above.
Answer: D
2) The process by which a single magma can generate several magmas of different compositions
is
A) partial melting.
B) partial crystallization.
C) fractional crystallization.
D) partial distillation.
Answer: A
3) A rock's initial melting temperature is primarily determined by
A) the rocks mineralogy.
B) its water content.
C) its internal temperature.
D) its heat source.
Answer: A
4) Magma that solidifies before reaching Earth's surface is called
A) intrusive igneous rock.
B) plutonic rock.
C) a pluton.
D) all of the above.
Answer: D
5) The two most common igneous rocks are basalt and granite. Basalt is commonly found
________, and granite is found ________
A) on the ocean floor; on the continents.
B) on both the ocean floor and continental land; only on the continents.
C) on the continents; on the ocean floor.
D) on the ocean floor; on both the ocean floor and on continental land.
Answer: B
6) The Hawaiian Islands are predominantly made up of
A) intrusive igneous rock.
B) volcanic igneous rock.
C) sedimentary rock.
D) metamorphic rock.
Answer: B
7) Basaltic volcanic eruptions tend to be
A) slow moving and highly viscous.
B) very fluid and highly viscous.
C) slow moving with a low viscosity.
D) very fluid and have a low viscosity.
Answer: D
8) The most common igneous rock is formed from
A) basaltic magma.
B) andesitic magma.
C) granitic magma.
D) none of these
Answer: A
9) The first minerals to crystallize are those having the
A) higher melting point.
B) lower melting point.
C) higher pressure.
D) lower pressure
Answer: A
10) As rock is heated, the first minerals to melt are those
A) with the highest melting point.
B) with the lowest melting point.
C) composed of granitic magma.
D) that have undergone partial distillation.
Answer: B
11) Rocks with a high water content have a
A) higher melting point.
B) lower melting point.
C) higher pressure.
D) lower pressure.
Answer: B
12) Igneous rocks are formed by the
A) melting and transformation of minerals in Earth's interior.
B) cooling and crystallization of molten magma.
C) partial crystallization of granitic magma.
D) cooling and crystallization of molten lava in Earth's interior.
Answer: B
13) Plutons form from magma
A) at Earth's surface.
B) below Earth's surface.
C) ejected from volcanoes.
D) all of these
Answer: B
14) Batholiths are massive plutons formed from the intrusion of
A) andesitic magma.
B) granitic magma.
C) basaltic magma.
D) all of these
Answer: B
15) The most common extrusive rocks are generated from
A) andesitic magma.
B) granitic magma.
C) basaltic magma.
D) none of the above
Answer: C
16) The most common outpouring of lava occurs as
A) volcanic eruptions.
B) carbonates.
C) conglomerates.
D) fissure eruptions.
Answer: D
17) Mauna Loa is a
A) cinder cone.
B) shield volcano.
C) composite volcano.
D) none of these
Answer: B
18) The most violent volcanic explosions are generally associated with
A) composite volcanoes.
B) cinder cones.
C) shield volcanoes.
D) none of these
Answer: A
19) The most violent volcanic explosions are generated from
A) basaltic lava flows.
B) andesitic lava flows.
C) granitic lava flows.
D) ocean floor lava flows.
Answer: B
20) The silica content of magma greatly affects its viscosity. Magma with a high silica content
has a
A) high viscosity and flows quickly.
B) high viscosity and flows slowly.
C) low viscosity and flows quickly.
D) low viscosity and flows slowly.
Answer: B
21) A composite volcano is formed by
A) successive flows of fluid basaltic lava.
B) a mixture of rock and lava.
C) alternating layers of lava, ash, and mud flow debris.
D) the accumulation of ash, cinders, and rock debris.
Answer: C
22) Most of the batholithic-sized plutons found in the continents are composed of
A) obsidian.
B) basalt.
C) granite.
D) sandstone.
Answer: C
23) The largest volumes of magma extruded on the continents are
A) flood and plateau basalts.
B) central-vent type volcanoes.
C) batholiths.
D) from volcanoes with a high silica content.
Answer: A
24) Beautiful cone-shaped volcanoes such as Mt. Fuji, Mt. Hood, and Mt. Rainer are
predominantly composed of
A) basaltic rocks.
B) andesitic rocks.
C) granitic rocks.
Answer: B
25) Lava can be
A) extruded from a volcano.
B) a cooled, solid rock.
C) intruded as a dike.
D) both A and B.
Answer: D
26) The largest volcano on Earth is a
A) shield volcano.
B) cinder cone.
C) composite cone.
D) lava plateau.
Answer: A
27) Shield volcanoes are composed of
A) andesitic magma.
B) basaltic magma.
C) granitic magma.
D) silica-rich magma.
Answer: B
28) Volcanic rocks form from
A) the eruption of viscous magma.
B) partial melting of basalt.
C) solidification of lava.
Answer: C
29) The volcanoes of the Hawaiian Islands are
A) stratovolcanoes.
B) composed of andesite.
C) shield volcanoes.
D) cinder cones.
Answer: C
30) The most common igneous rock is
A) basalt.
B) andesite.
C) granite.
D) none of these
Answer: A
31) The Earth's temperature increases with depth. Pressure also increases with depth from the
weight of the rock above. As pressure increases the
A) rock above begins to melt.
B) melting point of the rock (at depth) decreases.
C) melting point of the rock (at depth) also increases.
D) temperature increases, rocks begin to melt.
Answer: C
32) As rock melts to become magma, which minerals are the first to melt?
Answer: The first minerals to melt are those with the lowest melting points; because high silica
content minerals have relatively low melting temperatures they tend to melt more easily.
33) What is partial melting?
Answer: Partial melting is the incomplete melting of rock and minerals. The melting of different
minerals with their various melting points results in magmas of different compositions.
34) What does partial melting have to do with silica content of a magma?
Answer: Partial melting produces magmas with a higher silica content than the parent rock
because the high silica content minerals are the first to melt and the lower silica content minerals
are left unmelted.
35) Minerals in volcanic rocks are usually smaller than minerals in plutonic rock. Why is this?
Answer: Volcanic rocks form at Earth's surface. Plutonic rocks form beneath Earth's surface.
Because volcanic rock is extruded at the surface, it cools faster than plutonic rock. The shorter
the cooling time, the smaller the crystals.
36) What two factors can change a rock's melting point?
Answer: Pressure and water. Inside Earth, pressure increases with depth as a result of the
increased load of rock above. As pressure increases, melting point increases. The water content
of a rock also affects its melting point. Rocks with a higher water content have a lower melting
point. Rocks with a low water content have a higher melting point.
37) Relate silica content to crystallization from a magma.
Answer: First of all crystallization allows a single magma to generate several different igneous
rocks. Minerals with high melting points, have a low silica content, so will crystallize first,
followed by minerals with lower melting points (those containing larger amounts of silica). As
crystallization proceeds, the composition of the liquid in which the crystals form changes. It
becomes depleted in the constituents of minerals that have already crystallized and enriched in
the constituents of minerals yet to crystallize, which acts to increase the silica content of the
remaining liquid.
38) What is the difference between intrusive and extrusive igneous rocks?
Answer: Intrusive igneous rocks form below Earth's surface. Common intrusive rock formations
are called plutons and include sills, dikes, batholiths, and laccoliths. Intrusive rocks are often
referred to as plutonic rocks. Extrusive igneous rocks form at or very near Earth's surface.
Common extrusive rock formations include volcanoes and fissure eruptions. Extrusive igneous
rocks are often referred to as volcanic rocks.
39) How does silica content effect volcanic eruptions?
Answer: Silica content greatly effects magma viscosity. The greater the silica content, the greater
the viscosity (resistance to flow). Magmas with a high silica content flow slowly, while magmas
with a low silica content tend to flow more easily. As such, basaltic eruptions (low silica content)
are very fluid while andesitic eruptions (high silica content) flow slowly. The high resistance to
flow can act as a trap to gases in the magma that, as pressure builds up, can cause the volcano to
erupt explosively.
20.8 Sedimentary Rocks
1) Some ________ rock is formed from minerals that were once dissolved in water.
A) sedimentary
B) igneous
C) metamorphic
D) igneous and metamorphic
Answer: A
2) The three most common cementing agents in a sedimentary rock are
A) silica, calcite, and hematite.
B) calcite, silica, and iron oxide.
C) silica, carbonate, and feldspar.
D) silica, iron oxide, and sandstone.
Answer: B
3) The majority of surface rocks are
A) extrusive.
B) sedimentary.
C) intrusive.
D) metamorphic.
Answer: B
4) Of the following rocks, the one that does not originate in sediments laid down by water, wind,
or ice is
A) sandstone.
B) marble.
C) shale.
D) conglomerate.
Answer: B
5) As rock is weathered it breaks down and erodes. Sedimentation begins where erosion stops.
Erosion is
A) disintegration and fragmentation of rock into smaller pieces.
B) a chemical process.
C) decomposition and alteration of rock material.
D) transportation of rock particles via water wind or ice.
Answer: D
6) If the rock particles in a sedimentary rock are relatively small with well sorted and well
rounded grains, we can infer that the sediment grains traveled a
A) short distance.
B) long distance for a long time.
C) long distance in a short time.
D) short distance for a long time.
Answer: B
7) Limestone may be made up of
A) fragments of granitic and andesitic rocks.
B) animal bones.
C) shell fragments from marine animals.
D) plant debris.
Answer: C
8) Sedimentary rocks provide clues about past geologic events and settings. A low energy, quiet
environment such as a lagoon or lake bed provides the perfect setting for the formation of
A) sandstone and shale.
B) shale and evaporites.
C) arkose and dolomite.
D) none of these
Answer: B
9) The most common carbonate rock is
A) dolomite.
B) calcite.
C) halite.
D) limestone.
Answer: D
10) Layers of limestone in a rock outcrop often indicate that the area had at some time been
A) near the site of volcanic activity.
B) glaciated.
C) covered by water.
D) a desert area.
Answer: C
11) In a sedimentary rock, small rounded particles indicate a
A) long distance and long travel time.
B) short distance and short travel time.
C) long distance and short travel time.
D) short distance and long travel time.
Answer: A
12) In a wet and humid climate, the mineral halite will succumb to weathering more easily than
granite because
A) granite is more resistant.
B) halite readily dissolves in water.
C) halite is relatively soft (hardness of 2.5).
D) all of the above.
Answer: D
13) Petroleum and oil reserves are often found in sedimentary rocks because
A) these rocks are very porous and permeable.
B) chemical changes occur to create these reserves.
C) these rocks often contain fossilized organic matter.
D) oil accumulates in the sediments.
Answer: C
14) When rock is broken down into smaller and smaller pieces, we say the rock has undergone
A) chemical weathering.
B) mechanical weathering.
C) erosion.
D) lithification.
Answer: B
15) Carbonate deposition occurs in environments that are
A) warm and humid.
B) cool and wet.
C) monsoonal.
D) dry as deserts.
Answer: A
16) Ice wedging–freezing of water in cracks–is an example of
A) chemical weathering.
B) mechanical weathering.
C) iron oxide stain.
D) lithification.
Answer: B
17) Sediments convert to rock when they undergo
A) compaction and cementation.
B) lithification.
C) both A and B.
Answer: C
18) The type of fossilization that occurs when the remains of an organism are replaced by
mineral matter is called
A) carbonization
B) replacement.
C) an impression.
D) a cast.
Answer: B
19) Coal is formed from
A) anthracite.
B) deeply buried oil sediments.
C) swamps.
D) lithified peat.
Answer: D
20) Rocks break down to form sediment via
A) erosion.
B) transportation.
C) sedimentation.
D) weathering.
Answer: D
21) The main producer of sediment is
A) mechanical weathering.
B) ice wedging.
C) chemical Weathering.
D) erosion.
Answer: C
22) The most characteristic feature of sedimentary rocks is that they are
A) observed in great thicknesses.
B) formed in layered sequences–strata.
C) fossiliferous.
D) made from unconsolidated sediments.
Answer: B
23) How is erosion different from weathering?
A) Erosion is the process of removing sediment from weathered rock.
B) Erosion produces more sediment than weathering.
C) Erosion produces less sediment than weathering.
D) Erosion and weathering are different ways of saying the same thing.
Answer: A
24) Which of the following is NOT a characteristic of clastic sedimentary rock?
A) They are composed of small pieces of weathered rock.
B) They are classified by particle size.
C) They are created by precipitation.
D) They may contain organic matter.
Answer: C
25) Coal is considered to be a
A) biochemical sedimentary rock.
B) clastic sedimentary rock.
C) fossiliferous sedimentary rock.
D) chemical sedimentary rock.
Answer: A
26) What are the processes that transform sediment into sedimentary rock?
Answer: To get sediment, rock needs to weather (break down). Once weathered, erosion carries
away the raw material of sediment. The particles of sediment are then deposited, one layer upon
another. Time and accumulated periods of further deposition cause the sediments to compact and
harden. Fluids interacting with the sediment act as cementing agents further hardening the
sediment into sedimentary rock.
27) Pebbles of granite are very common in a conglomerate, whereas pebbles of marble are
relatively uncommon. Why is this? What are the properties of the different minerals in these
rocks?
Answer: Granite is predominantly composed of quartz and feldspar minerals. These minerals
(especially quartz) are very resistant to weathering. Conversely, marble is metamorphosed
limestone. Even though marble is hard and durable as a building stone it does succumb to
weathering. With time, marble may dissolve from the conglomerate.
28) How does sediment turn into sedimentary rock?
Answer: The transformation of sediments to sedimentary rock occurs in two ways–compaction
and cementation. As weight from overlying sediments presses down upon deeper layers,
sediment particles are squeezed and compacted together. This compaction squeezes water out of
the spaces between sediment particles. This water often contains in solution compounds such as
silica, calcite, and hematite. These compounds, which are chemically precipitated from solution,
partially fill the pore spaces with mineral matter and thereby act as cementing agents.
29) Which of the following rocks would be the first to weather in a humid climate? Which would
be the last? Defend your answers. (a) granite (b) sandstone (c) limestone (d) halite
Answer: Halite would be the first to weather since it is composed of NaCl and dissolves easily in
a humid environment. Granite would be the last to weather since it is very resistant to
mechanical and chemical breakdown.
30) How does sediment turn into sedimentary rock?
Answer: The transformation of sediments to sedimentary rock occurs in two ways: compaction
and cementation. As the weight of overlying sediments presses down upon deeper layers,
sediment particles are squeezed and compacted together. This compaction squeezes mineral rich
water out of the spaces between sediment particles and acts as a cementing agent.
20.9 Metamorphic Rocks
1) Slate is metamorphosed
A) granite, a foliated rock with alternating layers of dark platy minerals and lighter granular
minerals.
B) shale, a foliated rock composed of very small particles and flakes of mica.
C) marble, a foliated rock with water-tight crystals.
D) limestone.
Answer: B
2) Layered sedimentary rocks and foliated metamorphic rocks share similarities because
A) most foliated metamorphic rocks are derived from layered sedimentary rocks.
B) they both are formed layer upon layer.
C) the minerals in these two types of rocks form in parallel planes.
D) both rock types are subjected to compressive forces.
Answer: A
3) The layered appearance of foliated metamorphic rocks is due to the
A) laying down of micaceous minerals, layer upon layer.
B) realignment of sheet-structured minerals so that they are perpendicular to compressive forces.
C) recrystallization of minerals.
D) mechanical deformation of sheet-structured minerals.
Answer: B
4) A foliated metamorphic rock derived from granite is
A) gneiss.
B) quartzite.
C) slate.
D) marble.
Answer: A
5) A nonfoliated metamorphic rock composed of carbonate minerals is
A) gneiss.
B) quartzite.
C) slate.
D) marble.
Answer: D
6) The metamorphic property of flat or elongated mineral grains in parallel layers is called
A) schist.
B) cleavage.
C) foliation.
D) lithification.
Answer: C
7) Mica is not found in
A) slate.
B) schist.
C) gneiss.
D) quartzite.
Answer: D
8) A non-foliated metamorphic rock is
A) slate.
B) schist.
C) gneiss.
D) quartzite.
Answer: D
9) The rock that has undergone the greatest extent of metamorphic change is
A) gneiss.
B) slate.
C) shale.
D) schist.
Answer: A
10) Metamorphism caused by the close proximity of a magma source is called
A) contact metamorphism.
B) dynamic metamorphism.
C) regional metamorphism.
D) none of these
Answer: A
11) The metamorphic equivalent of limestone is
A) gneiss.
B) marble.
C) quartzite.
D) schist.
Answer: B
12) In contact metamorphism, we generally find
A) water-rich, high-temperature rocks at the contact border.
B) dry, high-temperature rocks at the contact border.
C) water-rich, low-temperature rocks at the contact border.
D) dry, low-temperature rocks at the contact border.
Answer: B
13) Rocks altered by heat and pressure beneath Earth's surface are
A) intrusive igneous rocks.
B) extrusive sedimentary rocks.
C) metamorphic rocks.
D) igneous rocks.
Answer: C
14) Limestone may be metamorphosed into
A) schist.
B) marble.
C) quartzite.
D) gneiss.
Answer: B
15) When the mineral assemblage of a rock changes due to high temperature and pressure, the
rock undergoes
A) crystal deformation.
B) secondary metamorphism.
C) recrystallization.
D) all of the above
Answer: C
16) Fluids in a metamorphic reaction
A) speed up the process.
B) neutralize the process.
C) slow down the process.
D) have no effect on the process of metamorphism.
Answer: A
17) Metamorphism caused by the alteration of rock by both thermal and mechanical means is
called
A) contact metamorphism.
B) dynamic metamorphism.
C) regional metamorphism.
D) none of the above
Answer: C
18) The characteristic that distinguishes schist from slate is that schist is
A) foliated and slate is not.
B) fine-grained and slate is coarse-grained.
C) coarse-grained and slate is fine-grained.
D) not foliated and slate is foliated.
Answer: C
19) Contact metamorphic rocks are typically not foliated because
A) the parent rock does not contain the correct type of minerals to produce foliation.
B) contact metamorphism occurs from heat and not from deformation due to stress.
C) contact metamorphism does not produce minerals, such as the micas, which are needed for
foliation to occur.
Answer: B
20) Foliation in metamorphic rocks is due to directed stress, which causes elongated minerals to
orient themselves
A) in parallel planes with the face of each plane parallel to the direction of maximum stress.
B) in alignment.
C) so that smaller crystals precede larger crystals.
D) in parallel planes perpendicular to the direction of maximum stress.
Answer: D
21) Regional metamorphic rocks are distinguished from igneous rocks because
A) they are finer grained.
B) regionally metamorphosed rocks are foliated and igneous rocks are not.
C) igneous rocks have interlocking grains and metamorphic rocks do not.
D) metamorphic rocks often have a "baked zone" and igneous rocks do not.
Answer: B
22) All of the following occur during metamorphism EXCEPT
A) melting.
B) recrystallization.
C) interaction with chemical fluids.
D) changes in composition.
Answer: A
23) Metamorphic foliation is
A) the same as sedimentary layering.
B) the prominent orientation of recrystallized minerals.
C) caused by the interaction with chemical fluids.
D) a layered appearance caused by mineral growth perpendicular to direction of pressure.
Answer: D
24) Zoned sequences of minerals are a characteristic of
A) contact metamorphism.
B) regional metamorphism.
C) foliated metamorphism.
D) mechanical deformation.
Answer: B
25) The metamorphism of coal to anthracite occurs due to
A) high pressure and high temperature.
B) high temperatures.
C) contact metamorphism.
D) crystallization of organic matter.
Answer: A
26) What are the chief types of metamorphic rocks?
Answer: Metamorphic rocks are defined by texture: foliated and nonfoliated. The kind of rock
produced depends on the parent rock and the grade of metamorphism. Foliated rocks include
slate, schists, and gneisses. Nonfoliated rocks include marble and quartzite.
27) Distinguish between metamorphic foliation and sedimentary layering.
Answer: Foliation is the realignment of minerals during recrystallization so that they are
perpendicular to the direction of compressive force. Sedimentary layering is the result of the
laying down of sediments one on top of the other.
28) Can metamorphism, caused solely by elevated temperature, occur without the presence of
magma? Why or why not?
Answer: Yes, by burial metamorphism. As rocks are buried, they slowly heat up (due to the
geothermal gradient) until they are in equilibrium with the crustal temperatures surrounding
them. This process can alter the mineralogy and texture of the rock.
29) What effect do fluids have on metamorphism?
Answer: Fluids enclosed in pore spaces act as a catalyst to aid metamorphic reactions. When a
rock is subjected to increased temperature and pressure, the amount of pore space decreases and
fluid is squeezed out. Fluids readily react with the surrounding rock. In general, the more fluid,
the faster the reaction.
20.10 The Rock Cycle
1) Rocks can begin to melt if
A) a decrease in pressure results in a sufficient decrease in the rock's melting point.
B) the rock's water content increases thereby decreasing the rock's melting point.
C) heated by rising magma from the Earth's interior.
D) all of the above.
E) none of the above.
Answer: D
2) As sediments accumulate, compaction and cementation produce sedimentary rock. This
process is called
A) consolidation.
B) solidification.
C) lithification.
D) solifluction.
Answer: C
3) Plutonic rocks subjected to high temperature and pressure transform by
A) recrystallization of existing mineral grains.
B) deformation of mineral grains.
C) melting down of existing minerals.
D) any of these
Answer: D
4) Most rock-forming minerals are members of the group called
A) silicates.
B) carbonates.
C) sulfates.
D) oxides.
Answer: A
5) Rocks formed by cooling from a molten state are
A) precipitated rocks.
B) igneous rocks.
C) sedimentary rocks.
D) metamorphic rocks.
Answer: B
6) The type of mineral formed is determined by
A) crystallization.
B) the elements present and the conditions that lead to formation.
C) silica content.
D) chemical bonding.
Answer: B
7) Sedimentary rocks subjected to melting become
A) lithified.
B) metamorphic rocks.
C) igneous rocks.
D) limestone.
Answer: C
8) Metamorphic rock that is weathered and broken down into small pieces can become
A) igneous rock.
B) recrystallized.
C) sediments which can then become sedimentary rock.
D) fossilized.
Answer: C
9) Andesitic magma produces
A) andesite rocks.
B) granitic rocks.
C) basaltic rocks.
D) metamorphic rocks.
Answer: A
10) Does the rock cycle always follow a certain path? In other words, is it a one-way process?
Answer: No, as its name implies, the rock cycle is cyclical and its routes vary. Igneous rock, for
example, may be subjected to heat and pressure far below Earth's surface to become
metamorphic rock. Or metamorphic or sedimentary rocks at Earth's surface may decompose to
become sediment that becomes new sedimentary rock. Cycles within cycles occur in Earth's
dynamic crust.
Test Bank for Conceptual Physical Science
Paul Hewitt, John Suchocki, Leslie Hewitt
9780321752932, 9780134060491
