Geo Exam 2

Gemstones are often found in pegmatites, which are igneous rocks that are

exceptionally coarse grained.

The blueschist facies form under which of these conditions:

high pressure but relatively low temperature

A pegmatite is a course-grained igneous rock that forms primarily because the melt

is water-rich

Because of its physical properties, magma tends to

move upward, away from where it formed.

Two common metamorphic rocks that typically lack foliation are ________ and ________.

quartzite; marble

In silicate minerals, the SiO4 tetrahedron can be chemically bonded to form all of the following EXCEPT

triple chains.

The majority of the rocks that form at the surface of the Earth are

sedimentary rocks.

________ commonly serves as a protolith in the formation of phyllite.

shale

________ commonly serves as a protolith in the formation of slate.

shale

Which of the following is a type of physical weathering?

thermal expansion

The photo shown below is a(n) ________ that geologists can use to study the minerals in the rock.

thin section

If the climate in an area has very little rainfall, what would be the characteristics of the soil in the area?

thin, with very little organic material

Igneous rocks are formed

through the freezing or crystallization of a melt.

Sea level rises locally, and marine sediments are deposited on top of terrestrial sediments during events termed

transgressions.

Grains become rounded primarily during

transportation

Chemically precipitated limestone that forms in caves or around hot springs is termed

travertine

The image below shows a series of graded beds. How many graded beds are shown?

3

Which of the following materials has been MOST altered from its original bedrock?

A

Which soil horizon is the most important to farmers for planting crops?

A

Which of the following is NOT true concerning the color of minerals?

A mineral's color reflects the wavelengths of light that are absorbed by the mineral.

Which of the following is NOT true about minerals

All minerals are compounds of more than one element.

Which letter corresponds to the regolith in the following picture?

B

Using the Mohs hardness scale below, which of the following statements is false?

Diamonds are twice as hard as apatite.

Why does differential weathering occur?

Different minerals have different resistances to weathering.

How would you tell if a rock is crystalline?

It contains interlocking crystals.

Which of the following statements cannot be applied to the extrusive igneous rock obsidian?

It cools very slowly.

Which of the following is true regarding biochemical chert?

It is made of cryptocrystalline quartz.

Which of the following is a primary difference between phyllite and schist?

Mica crystals within schist are larger than those within phyllite

What is the difference between a rock that is cemented together and a rock that has a crystalline texture?

Minerals are held together as interlocking pieces in a crystalline rock, whereas in a cemented rock the grains do not fit together like puzzle pieces and instead are held together by cement.

Which of the following is the most important characteristic used to identify minerals?

Multiple properties must be used to identify a mineral.

Which soil horizon contains the most organic material?

O

Why does physical weathering speed up the processes of chemical weathering?

Physical weathering produces more surface area for chemical weathering to attack.

________ metamorphism affects the greatest volumes of rock and produces the greatest variety in metamorphic rock

Regional

Pyrite (FeS2) is in which mineral class?

Sulfides

What is the difference in the formation of chalk versus chert?

They are made of different source materials.

Which of the following is true about regressions?

They occur when the land is uplifted by tectonic processes.

Which of the following describes a rock?

a collection of crystals that fit together like puzzle pieces

Minerals are all naturally occurring solid substances with a definable chemical composition. They must also possess

a fixed crystalline structure (spatial arrangement of atoms and ions)

Which of the following would NOT be considered a rock?

a natural pile of unconsolidated sand

If you find a tuff in the field, what type of geologic activity could you reasonably assume has occurred?

a volcanic eruption

Hydration occurs when minerals

absorb water and expand

Which environment would most likely produce sedimentary deposits characterized by poorly to moderately sorted, angular to subangular grains that consist of feldspar, quartz, and lithics (rock fragments)?

alluvial fan

The image below of Death Valley, CA, shows a road that curves around a(n)

alluvial fan.

Dissolution occurs when minerals

are dissolved into water

Most commonly, felsic igneous rocks

are lighter in color than mafic rocks.

Consult the figure below. Compared with low-grade metamorphic rocks, high-grade rocks

are produced at greater temperatures and pressures.

Of the ~4,000 known minerals, the vast majority

are rare

Silicate minerals are subdivided into six groups based on the way silica tetrahedra are

arranged and bonded.

Precambrian metamorphic rocks are exposed at the surface

at places in continental interiors (called shields).

In which of the following settings would you be most likely to find sedimentary rocks forming?

at the bottom of the Mediterranean Sea

Consult the figure below. The region of thermally metamorphosed rock surrounding a cooled pluton is called a (n)

aureole.

Mylonites, formed from dynamic metamorphism, typically do NOT display

bands of randomly oriented mica grains.

A vast, composite intrusive igneous body that covers hundreds of square kilometers (in a map view) is called a

batholith.

Differentiation of the Earth's iron core and collisions of planetesimals caused early Earth to

be much hotter than at present.

Because the velocity of sediment settling (deposition) is positively related to grain size for waterborne sediments, fluvial deposits are more likely than glacial deposits to

be well sorted.

Which environment would most likely produce sedimentary deposits characterized by very well-sorted, very well-rounded grains that are nearly pure quartz?

beach

Geologists call individual layers of sedimentary rocks ________, whereas several of them together are called ________.

beds; strata

Hardness refers to a mineral's ability to resist

being scratched

Cemented shells of marine organisms form which kind of sedimentary rock?

biochemical

The rapid, deep burial of sediments in an accretionary prism leads to the formation of a metamorphic rock termed

blueschist

Minerals can crystallize in all of the following ways EXCEPT

bonding carbon to oxygen atoms to form organic compounds

Volatiles refer to substances that

evaporate easily and exist as gases.

Marble and quartzite are nonfoliated metamorphic rocks because

both are dominated by minerals that produce equant grains.

A shale differs from a mudstone in that it

breaks into platy sheets

The image below shows a mineral with hydrochloric acid applied to it. Based on the reaction and presence of gas bubbles, which of the following minerals is this most likely to be?

calcite

Diamond and graphite are both polymorphs of

carbon

Calcite (CaCO3) is in which mineral class?

carbonates

Which of the following processes are NOT involved in metamorphism?

cementation and compaction of grains during diagenesis

Which of the following are NOT considered sediments?

cemented grains

Broadly, metamorphism involves

changes in mineralogy and texture in response to heat and stress

Precipitation of gypsum due to evaporation of seawater produces which kind of sedimentary rock?

chemical

Minerals are grouped into mineral classes primarily on the basis of

chemistry, specifically the anions within the chemical formula.

Lithified detritus (breakdown products of preexisting rocks) forms which kind of sedimentary rock?

clastic

hick accumulations of sediments and fossils in the deep ocean tend to be ___________-sized because of the low amount of energy in the environment.

clay

What type of sediment is typically found in lake bottoms?

clay/mud

The tendency for minerals to break along distinct planar surfaces that have a specific orientation in relation to the crystal structure called

cleavage

As compared to aphanitic igneous rocks, phaneritic rocks are

coarser grained.

Trace amounts of impurity can produce significant differences in ________ among individual crystals of a mineral species

color

Fewer than 50 minerals are

commonly found in rocks

Which of the following processes does NOT occur in the formation of metamorphic rock?

complete remelting of the rock, followed by solidification to form a new rock

Which of the following is NOT true? Sediments deposited in a beach environment are typically

composed of angular grains.

The image below shows a mineral specimen of quartz. What is the term for the smoothly curving, clamshell-shaped surface on the sample?

conchoidal fracture

Glass and quartz crystals exhibit a smoothly curving, clamshell-shaped fracture pattern termed

conchoidal fracture.

The image below shows an outcrop of coarse-grained sedimentary rock. Note the rock hammer for scale. What is the name of this rock type?

conglomerate

Consult the figure below. Compared with amphibolite metamorphic facies, greenschist facies

consist of lower-grade rocks.

The boundary formed between new intrusive igneous rock and the host rock around it is called a

contact

Which of the following common minerals is hardest?

quartz

A volcanic arc results from __________ tectonic movements and is associated with a __________.

convergent; subduction zone

As compared to coarse-grained igneous rocks, fine-grained igneous rocks

cool and solidify more quickly.

Intrusive rocks that form deep within the Earth ______________ than intrusive rocks that cool near the surface.

cool more slowly

What type of texture is shown in this photomicrograph?

crystalline

In the formation of gneiss from a granite protolith, distinctive compositional bands form because of

crystals dissolving, with atoms and ions migrating and reorganizing as new crystals.

A body of rock starts at location A in the graph below. The rock, over a period of time, moves to location B and begins to melt. This is an example of melting due to

decompression.

If the volatile content of magma is increased, its viscosity will

decrease

Vesicles in an igneous rock are evidence for which of the following?

degassing of volatiles

Topset, foreset, and bottomset beds are indicative of ________ environments.

delta

The mineral assemblage within metamorphic rock is

dependent on both the mineral content of the protolith and the temperature and pressure of formation

Large layers of cross-bedded sand can be indicative of a ____________ environment.

desert

The application of ________ during metamorphism causes elongated crystals to align parallel with each other. When this happens, the rock develops ________.

differential stress; foliation

In the figure provided below, what type of igneous intrusion is the vertical rock unit shown by letter A?

dike

Salt water is the end product of this weathering process.

dissolution

Naturally forming glass (such as obsidian) is NOT considered a mineral because it

does not have a fixed crystalline structure.

When limestone becomes chemically altered so that half of the calcium atoms are replaced by magnesium, the resultant rock is termed

dolostone

The Dust Bowl of the 1930s was created by which phenomenon?

drought

Which of the following is not typically associated with the eruption of a Large Igneous Province (LIP)?

emplacement of large granite batholiths

Differential stress will cause crystals to align in a preferred orientation unless the crystals are

equant

The removal of detritus from weathered rock at an outcrop is termed

erosion

Crystals that exhibit well-formed faces are referred to as

euhedral

The diamonds we typically see today in engagement rings do not display their natural crystal faces but rather ________,which are made by grinding the gem on a spinning lap.

facets

Which type of magma has the greatest silica content?

felsic

Large igneous provinces are formed by ________, which can flow tens to hundreds of kilometers.

flood basalts

Rocks resulting from thermal (contact) metamorphism will NOT possess

foliation

Slaty cleavage, schistosity, and compositional banding are all examples of

foliation

Basins that form on the continental side of mountain ranges are called _________ basins.

foreland

Which of the following statements is false? Hornfels facies rocks

form at high pressures and low temperatures.

Minerals that do not possess cleavage are said to possess

fracture

In which type of silicates are the greatest proportion of oxygen atoms shared by pairs of adjacent tetrahedra?

framework silicates

What type of weathering are you most likely to find occurring in areas with cold climates?

frost wedging

Which of the following minerals is more commonly known as table salt?

halite

As compared to mafic igneous rocks, felsic igneous rocks

have a higher proportion of silica relative to Mg oxide and Fe oxide.

Ore minerals, such as galena and hematite, tend to be different from typical minerals in that they have a

high specific gravity.

Consult the figure below. Hot water reacting with the crust is the basis for what type of metamorphism?

hydrothermal

Which transport medium carries the largest particles?

ice in glaciers

Which of the following is a mineral?

ice, which is water in the solid state

A body of gneiss is subjected to heat and forms a melt. Later, the melt cools and crystallizes to form a (n) ________ rock

igneous

What type of rock is being formed in the photo?

igneous

What type of rock would you expect to form from volcanic activity?

igneous

Which type of rock forms from the freezing (solidification) of a melt?

igneous

If a body of magma becomes more felsic, its viscosity will

increase

A mineral within a metamorphic rock that can be used to narrowly constrain the temperature and pressure of rock formation is termed a (n) ________ mineral.

index

Chemical weathering involves the breakdown of material due to

interaction with water or air.

Shiprock, New Mexico, seen in the photo below is a(n)

intrusion that represents the eroded remnant of an extinct volcano.

When magma solidifies below the surface of the Earth, ________ are formed.

intrusive igneous rocks

Regional metamorphism

is another name for dynamothermal metamorphism.

Within a single mountain range,

it is possible to find a variety of metamorphic rocks produced in distinct facies, including high-, low-, and intermediate-grade rocks

The following is a picture of what type of phenomenon?

jointing

What type of weathering has created the onion-like layers in the rocks in the picture?

jointing

Diamonds are usually found in a rock called

kimberlite

Differential weathering occurs when

layers of rock weather at different rates

________ commonly serves as a protolith in the formation of marble.

limestone

Compaction and cementation of grains occurs during

lithification

Which of the following processes is not responsible for the formation of magma within the Earth?

loss of volatiles to the atmosphere

The way a mineral scatters light is a diagnostic property termed

luster

A majority of the melts in the Earth form through the partial melting of ultramafic mantle rock. These newly formed magmas are

mafic

The difference between magma and lava is

magma is melt underground, whereas lava is melt that has emerged from the surface.

A protolith

may belong to any of the three primary rock types.

Injecting hot fudge into ice cream and causing the ice cream to melt is an appropriate analogy for which cause of magma melt

melting due to heat transfer from rising magma

If a rock is subjected to elevated levels of heat and pressure, a(n) ________ rock will form.

metamorphic

What type of rock is shown in the photo below?

metamorphic

What do geologists call the layering seen in this photo?

metamorphic foliation

A buried body of shale is subjected to differential stress, causing clay minerals to realign and produce slate. This is an example of

metamorphism.

Clay minerals within a buried body of slate are recrystallized at high temperatures and pressures to form mica, producing a rock called phyllite. This is an example of

metamorphism.

The net chemical change in a metamorphic rock induced by a reaction with hot groundwater is termed

metasomatism.

Chemical sedimentary rocks are classified primarily on the basis of

mineral composition.

Foliated metamorphic rocks possess

mineral grains in preferred orientations or patterns of association.

The zone of leaching is the area in which

minerals are dissolved and removed from soil

In general, when rock is partially melted, the chemistry of the melt is

more felsic than the original chemistry of the rock that was partially melted.

In general, if a body of igneous (source) rock is subjected to partial melting, the magma that is produced is expected to be

more felsic than the source rock.

During fractional crystallization of a magma body, the first rock that is expected to crystallize from the magma will be

more mafic than the magma.

The sedimentary rocks breccia and conglomerate most commonly form in a ________ environment.

mountain

Rocks are ________ and thus not human-made.

natural

Sedimentary rocks are most likely to form

near the Earth's surface.

Thermal (contact) metamorphism produces

nonfoliated rocks only

A heavy book is placed on top of a ball of pizza dough, causing the dough to flatten. This is an application of

normal stress.

In the discontinuous series of Bowen's reaction series, the first mineral to crystallize from a mafic melt is

olivine.

The most recently formed portion of any crystal is always found

on the outer edges.

For the majority of minerals, the streak obtained when the mineral is scratched against a porcelain plate is

only useful if the mineral is softer than the porcelain streak plate.

Two major sources of energy, coal and oil shale, are considered ________ sedimentary rocks.

organic

What type of weathering has altered the pyrite crystals in the picture?

oxidation

Which type of weathering process is happening to materials when they rust?

oxidation

Which common gemstone results from biomineralization?

pearl

An igneous rock with a mixed texture consisting of coarse crystals (phenocrysts) surrounded by fine crystals (groundmass) is termed

phaneritic.

Diagenesis refers to

physical and chemical alterations, including compaction and cementation, that occur as sediment is transformed into rock

The figure below shows mafic magma as it meets the seafloor, which cools to form an igneous rock called

pillow basalt.

The continuous series in Bowen's reaction series describes the crystallization behavior of which mineral?

plagioclase

A _________ is an irregular or blob-shaped intrusive body; a ___________ is a blister-shaped intrusion.

pluton; laccolith

When two different minerals have the same chemical formula but different crystal structures, they are said to be

polymorphs

Pegmatites, which often occur in dikes, are unusual among shallow intrusive rocks in that they

possess exceptionally coarse grains.

The primary difference between breccia and conglomerate is that conglomerate

possesses more rounded grains than breccia.

The transformation of low-grade metamorphic rocks into high-grade metamorphic rocks is termed ________ metamorphism.

prograde

Composition describes the

proportion of chemicals that make up a rock.

The preexisting rock that is subsequently altered to form a metamorphic rock is termed a

protolith

A felsic, highly-vesicular volcanic rock is termed

pumice

A fragmental, extrusive igneous rock is referred to as which of the following?

pyroclastic

Bombs, ash, and cinders are all examples of

pyroclastic debris.

Which of the following best explains how a metamorphic rock forms?

recrystallization due to changes in pressure and temperature

The transformation of high-grade metamorphic rocks into low-grade metamorphic rocks is termed ________ metamorphism.

retrograde

Granite, an intrusive igneous rock, is most similar in mineral composition to which extrusive equivalent?

rhyolite

Pulling a block of clay apart, resulting in the middle portion thinning and sinking, is an adequate analogy for

rift basins and subsidence.

Which of the following is NOT part of the process that leads to the exhumation of metamorphic rocks?

rising plumes of magma in the mantle

A well-sorted sandstone with asymmetric ripples was most likely deposited as sand by a

river (far from source).

Dynamothermal (regional) metamorphism occurs when

rock becomes deeply buried during continental collision and mountain building.

Why do geologists classify rocks?

rocks are the key to understanding how the Earth formed

What type of weathering are you most likely to find occurring on the coast?

salt wedging

What type of weathering has produced the honeycomb-like features shown in the following photo?

salt wedging

________ commonly serves as a protolith in the formation of quartzite.

sandstone

Which two gems are varieties of the mineral corundum (Al2O3)?

sapphires and rubies

A preferred orientation of large, flaky mica crystals within metamorphic rock is termed

schistosity

Granite is a type of rock that forms deep underground from magma that cools very slowly. What type of rock is granite?

sedimentary

Imagine you are holding a rock composed of small sand grains cemented together. What subclassification of sedimentary rock is this

sedimentary

What type of rock is shown in the photo? (bedding)

sedimentary

What type of rock would you most expect to find forming in a beach environment?

sedimentary

Which type of rock is formed by precipitation of minerals from a solution?

sedimentary

Which of the following are most likely to preserve conditions of ancient environments on the Earth?

sedimentary rocks

Which of the following describes the progression of rock types through increasing metamorphic grade from left to right?

shale → slate → phyllite → schist

Limestone is most likely formed in which of the following environments?

shallow-marine carbonate

The figure below shows the application of

shear stress

Spreading peanut butter on bread is an application of

shear stress.

The mineral class that makes up more than 95 percent of the continental crust is termed the

silicates.

In the figure provided below, what type of igneous intrusion is the horizontal rock unit shown by letter A

sill

Biochemical limestones are dominated by carbonate mud and fragments of

skeletons of marine invertebrates made of calcite and aragonite.

Which list properly orders foliated metamorphic rocks from lowest to highest grade from left to right?

slate, phyllite, schist, and gneiss

Weathering results in

smaller, more rounded pieces

A magma body with a ________ volume and a ________ shape cools fastest.

smaller; pancake

A mineral property defined as the density of the mineral sample divided by the density of water (1.0 g/cm3) is

specific gravity.

The color of a mineral in powdered form is termed

streak

The image below shows a mineral specimen of pyrite. What is the term for the thin parallel corrugations or stripes shown on the crystal faces below?

striations

Death Valley is currently sinking partly due to the weight of continuously accumulating sediment shed from the mountains that border the valley. What phenomenon is this an example of and what depositional environment is created

subsidence and alluvial fans

Flood basalts such as those found in the Columbia Plateau and the Deccan region are associated with

superplumes

As compared with metamorphism, diagenesis

takes place at lower temperatures and pressures

Which of the following common minerals is softest?

talc

Which of the following does not affect the cooling rate of magma?

tectonic setting

The geotherm is the rate of change of

temperature with depth in the Earth's interior.

Which of the following is a reliable characteristic that can be used to classify a rock?

texture

The electron microprobe, a commonly used analytical instrument in geology, focuses a beam of electrons on a sample to determine

the chemical composition.

Minerals in geodes (as seen below) form spectacular euhedral crystals because

the crystals have abundant room to grow in their hollow surroundings

Stratification refers to

the development of layering within sedimentary rocks

Viscosity does NOT depend on

the total volume of the magma body.

Fragments of material erupted from a volcano eventually settle and lithify to form an extrusive igneous rock called

tuff

When graded beds are observed in a rock outcrop, this tells geologists that a

turbidity current deposited these beds, depositing coarser material first

Which of the following is LEAST likely to affect soil thickness?

types of animals

If water is the transport mechanism of sediment, the grain size of sedimentary deposits most closely indicates the

velocity of the water at the moment the sediment settled to the bottom.

If a geologist found preserved mud cracks, he or she could conclude that the environment in which they formed

was once covered in wet mud.

Retrograde metamorphism will not occur unless an increased amount of ________ is added to the system.

water

Important volatiles in magmas include

water and carbon dioxide.

Symmetric ripples form when

water deposits sediment in layers, but the direction of flow periodically changes

Potassium feldspar reacts with water to form clay. This is an example of

weathering

Sediment formation is the result of __________ at the Earth's surface.

weathering

The breakdown of exposed rock into small fragments and dissolved ions is termed

weathering

What can geologists most easily determine by analyzing a thin section?

what minerals constitute the rock and how grains connect to one another

It is unusual for ________ to carry grains larger than sand.

wind

The pattern of atoms in a crystal can be detected using

x-ray diffraction.