GEO EXAM 2 HARRIS
A pegmatite is a course-grained igneous rock that forms primarily because the melt
is water-rich
Two common metamorphic rocks that typically lack foliation are ________ and ________.
quartzite; marble
Which of the following describes the progression of rock types through increasing metamorphic grade from left to right?
shale --> slate --> phyllite --> schist
Which of the following is a type of physical weathering?
thermal expansion
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
Why does differential weathering occur?
Different minerals have different resistances to weathering
________ commonly serves as a protolith in the formation of marble.
Limestone
Which of the following is a primary difference between phyllite and schist?
Mica crystals within schist are larger than those within phyllite
Why does physical weathering speed up the processes of chemical weathering?
Physical weathering produces more surface area for chemical weathering to attack
________ commonly serves as a protolith in the formation of quartzite.
Sandstone
________ 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 true about regressions?
They occur when the land is uplifted by tectonic processes
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. The region of thermally metamorphosed rock surrounding a cooled pluton is called a (n)
aureole
A vast, composite intrusive igneous body that covers hundreds of square kilometers (in a map view) is called a
batholith
Cemented shells of marine organisms form which kind of sedimentary rock?
biochemical
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
Lithified detritus (breakdown products of preexisting rocks) forms which kind of sedimentary rock?
clastic
What type of sediment is typically found in lake bottoms?
clay/mud
As compared to aphanitic igneous rocks, phaneritic rocks are
coarser grained
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
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. Here, distinct internal laminations are inclined at an angle to the boundary of the main sedimentary layers. These are termed
cross beds
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 assemblage of its protolith and the temperature and pressure of formation
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
The Dust Bowl of the 1930s was created by which phenomenon?
drought
Differential stress will cause crystals to align in a preferred orientation unless the crystals are
equant
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
As compared to mafic igneous rocks, felsic igneous rocks
have a higher proportion of silica relative to Mg oxide and Fe oxide
Which transport medium carries the largest particles?
ice in glaciers
If a body of magma becomes more felsic, its viscosity will
increase
Chemical weathering involves the breakdown of material due to
interaction with water or air
Shiprock, New Mexico, seen in the photo below is a
intrusion that represents the eroded remnant of an extinct volcano
When magma solidifies below the surface of the Earth, ________ are formed.
intrusive igneous rocks
Within a single mountain range,
it is possible to find a variety of metamorphic rocks produced in distinct facies, including high-, intermediate-, and low-grade rocks
Differential weathering occurs when
layers of rock weather at different rates
Compaction and cementation of grains occurs during
lithification
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
A buried body of shale is subjected to differential stress, causing clay minerals to realign and produce slate.
metamorphism
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.
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
Sedimentary rocks are most likely to form
near the Earth's surface
In the discontinuous series of Bowen's reaction series, the first mineral to crystallize from a mafic melt is
olivine
Two major sources of energy, coal and oil shale, are considered ________ sedimentary rocks.
organic
Which type of weathering process is happening to materials when they rust?
oxidation
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
Pegmatites, which often occur in dikes, are unusual among shallow intrusive rocks in that they
possess exceptionally coarse grains.
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
Granite, an intrusive igneous rock, is most similar in mineral composition to which extrusive equivalent?
rhyolite
A well-sorted sandstone with asymmetric ripples was most likely deposited as sand by a
river (far from source)
The majority of the rocks that form at the surface of the Earth are
sedimentary rocks
Which of the following are most likely to preserve conditions of ancient environments on the Earth?
sedimentary rocks
The figure below shows the application of
shear stress
Which list properly orders foliated metamorphic rocks from lowest to highest grade from left to right?
slate, phyllite, schist, and gneiss
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
The geotherm is the rate of change of
temperature with depth in the Earth's interior
Stratification refers to
the development of layering within sedimentary rocks
Viscosity does NOT depend on
the total volume of the magma body
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
Important volatiles in magmas include
water and carbon dioxide
Sediment formation is the result of __________ at the Earth's surface
weathering
It is unusual for ________ to carry grains larger than sand.
wind
