Geology midterm

1. The world’s population growth rate
a. increases with time
b. is constant
c. is variable over time
d. was the highest in the 19th century

variable over time

2. The Hubbert Peak
a. is a mountain in the Himalayas
b. is a peak in the Rocky Mountains
c. is the predicted time of the maximum U. S. oil production
d. is the predicted time of the maximum U. S. coal production

is predicted time of the maximum US Oil production

Which of the following is the broadest group of renewable energy resources?
a. Sun
b. Wind
c. Coal
d. a and b

a and b

The most significant limitation to our ability to predict future climate change is
a. Slow computers
b. Inadequate understanding of complex interactions between the atmosphere and
the hydrosphere
c. Uncertainty in future greenhouse-gas emissions
d. b and c

b and c

With respect to the giant planets, the terrestrial planets
a. are rich in iron and magnesium and poor in volatiles
b. are poor in iron and magnesium and rich in volatiles
c. are composed of materials of high boiling points
d. a and c

a and c

The heat engine that drives geological processes and plate tectonics is
a. radiation from the Sun
b. the Earth’s internal heat flow from the hot core to the cold surface
c. gravitational effects of the Moon
d. a and c but not b

the Earth's internal hear flow from the hot core to the cold surfaces

Descending limbs of convection cells may be present beneath
a. continental mountain ranges
b. geographic poles
c. oceanic trenches
d. geomagnetic poles

oceanic trenches

The vertical angle between a magnetic line of force and the Earth’s surface is
a. the inclination
b. measured by a gravimeter
c. the paleomagnetism
d. always 90°

the inclination

The “normal” gravity field of the spherical non-rotating Earth is approximately
a. 1 m/s2
b. 106 Gal
c. 980 Gal
d. 5.1 kg

980 Gal

The island of Iceland is formed over
a. an old continental crust
b. spreading mid-Atlantic ridge
c. a convergent plate boundary
d. none of the above

spreading mid-atlantic ridge

A silica tetrahedron is composed of
a. one silicon atom and three oxygen atoms
b. one silicon atom and four oxygen atoms
c. one silicon atom and three hydroxide molecules
d. five silicon atoms

one silicon atom and four oxygen atoms

An example of a silicate mineral with a double-chain structure is
a. hornblende
b. corundum
c. plagioclase feldspar
d. halite

hornblende

Clay minerals often cause foundation problems because they expand upon increases
in water content. The most expansive clay mineral is
a. fluorite
b. montmorillonite
c. galena
d. hematite

montmorillonite

Which chemical formula represents the mineral fluorite, belonging to the halide
(fluoride) group?
a. CaCO3
b. CaF2
c. PbS
d. NaCl

CaF2

Hot-spring deposits composed of calcite fall into the
a. sulfate mineral group
b. silicate mineral group
c. oxide mineral group
d. carbonate mineral group

carbonate mineral group

The rate of cooling of an igneous rock can be determined by the
a. silica content
b. color
c. quartz content
d. texture

texture

The chemical composition of a magma is most likely indicated by
a. the color of the resulting rock
b. the texture of the resulting rock
c. the orientation of the bedding planes in the resulting rock
d. none of the above

The color of the resulting rock

The texture of granite (intrusive igneous rock) is
a. aphanitic
b. phaneritic
c. vesicular
d. glassy

phaneritic

If a specimen of granite were slowly heated, which mineral would melt first?
a. Muscovite
b. Plagioclase
c. Quartz
d. All simultaneously

Quartz

The physical and chemical processes involved in conversion of a sediment to a
sedimentary rock are collectively known as
a. cementation
b. lithification
c. compaction
d. crystallization

lithification

1. Sedimentary rocks that originated as deposits near the center of a large lake should
have
a. graded bedding
b. parallel bedding
c. cross-bedding
d. felsic composition

parallel bedding

A boundary between sedimentary units in which the overlying unit was deposited
very soon (temporally continuously) after the lower is
a. a horst
b. a conformable contact
c. a principal plane
d. formed by uplift and erosion

a conformable contact

Pinchouts in sedimentary sequences are typically formed during
a. differentiation of magma
b. crystallization according to Bowen’s reaction series
c. lithification of detrital sediments
d. marine transgressions-regressions

marine transgression-regressions

Metamorphic rocks are produced from
a. igneous rocks
b. sedimentary rocks
c. a and b
d. ferromagnesian minerals

a and b

Parallel orientation of mineral grains within a metamorphic rock is called
a. foliation
b. aphanitic texture
c. phaneritic texture
d. graded bedding

foliation

Which of the following rocks are often non-foliated?
a. Slate
b. Fault breccia
c. Marble
d. b and c

b and c

Slate is a rock that was probably produced by metamorphism of
a. sandstone
b. limestone
c. shale
d. olivine

shale

A measure of the volume of void space relative to the total volume of earth material is
called
a. porosity
b. intrinsic permeability
c. hydraulic conductivity
d. texture

porosity

Stresses of equal magnitude that are offset and oriented in opposite directions are
a. normal stresses
b. compressive stresses
c. shear stresses
d. principal stresses

shear stresses

Which statement about elastic deformation is NOT true?
a. Elastic strain is completely recoverable
b. Stress is directly proportional to strain rate
c. The constant of proportionality between stress and strain is called modulus of
elasticity
d. The model for elastic deformation is a spring

Stress is directly proportional to strain rate

The illustration below shows three Mohr circles. Assuming the scale is the same for
each diagram, indicate which of these exhibits the greatest shear stress for the plane
shown.
a. Fig. 1
b. Fig. 2
c. Fig. 3

Fig 2

The angle of internal friction is
a. the slope of a line showing shear strength as a function of normal stress
b. the constant of proportionality between stress and strain rate
c. the angle between cleavage planes of a mineral
d. the angle between maximum and intermediate principal stresses

The slope of a line showing shear strength as a function of normal stress

The jointing characteristics of a rock mass strongly influence the
a. strength
b. movement of fluids through the rock mass
c. slope stability
d. all of the above

all of the above

The San Andreas fault in California represents a
a. divergent boundary
b. subduction zone
c. strike-slip fault
d. joint

strike-slip fault

5. In a strike-slip fault
a. the hanging wall moves up with respect to the footwall
b. the hanging wall moves down with respect to the footwall
c. the fault-plane dip angle is small
d. none of the above

none of the above

The type of displacement on the fault plane in the picture is __________________,
and it is typically caused by the __________________ stress regime
a. normal and compressional
b. reverse and compressional
c. reverse and tensional
d. strike-slip and shearing

Reverse and compressional

The subsurface point of initiation of rupture of an earthquake is called the
a. center of rupture
b. epicenter
c. hypocenter
d. rift

hypocenter

Locked sections of the San Andreas fault that periodically generate earthquakes can
be explained by
a. the elastic-rebound theory
b. the presence of a mantle plume below
c. the theory of isostasy
d. the sea-floor spreading theory

the elastic-rebound theory

The most significant seismic hazard is
a. ground failure
b. tsunamis
c. ground shaking
d. dip-slip faulting

ground shaking

It is believed that the collapse of the Cypress Structure (Bay Bridge access ramp)
during the Loma Prieta earthquake occurred due to
a. poor quality of construction
b. surface faulting
c. amplification of ground motions by soft geologic deposits
d. foliation of underlying rocks

amplification of ground motions by soft geologic deposits

The global-population doubling time given the current growth rate is
a. 53 years
b. 111 years
c. 1000 years
d. 20 years

53 years

Which of the following terms refers to the size or intensity of a geologic event?
a. Frequency
b. Recurrence interval
c. Magnitude
d. All of the above

Magnitude

Positive and negative magnetic anomalies preserved in basalt in the ocean floor are
parallel to midocean ridges and
a. record when basalt erupted and cooled during times of normal magnetic
polarity and times of reversed magnetic polarity
b. are symmetrical about mid-ocean ridges, indicating that paired sets of
anomalies on either side of a ridge formed at the same time
c. both a and b
d. are caused by variations in the amount of magnetic minerals present in the
basalt

both a and b

The increase in the Earth’s normal gravity from the equators to the poles is caused by
a. Earth’s rotation
b. geomagnetic dynamo
c. surface topography
d. variations in subsurface density

Earth's rotation

Measured values of gravity need to be corrected to
a. Eliminate the effect of heterogeneous mass distribution within the Earth
b. Reduce all readings to the level of the non-rotating geoid
c. Convert all measurements to the same physical units
d. Compensate for the differences between different types of gravimeters

Reduce all readings to the level of the nonrotating geoid

The silicate-mineral structure shown below is an example of a
a. sheet silicate (micas and clays)
b. single-chain silicate (pyroxene)
c. basic-form silicate (olivine and garnet)
d. framework silicate (quartz and feldspar)

basic-form silicate (olivine and garnet)

Which of the following minerals belongs to the carbonate group?
a. Gypsum
b. Pyrite
c. Dolomite
d. Amphibole

Dolomite

CaF2 is the chemical formula of the mineral
a. fluorite
b. galena
c. orthoclase
d. diamond

Fluorite

The aphanitic (extrusive) equivalent of gabbro is
a. rhyolite
b. granite
c. basalt
d. gneiss

basalt

Which of the following minerals make up the continuous side of Bowen's reaction
series?
a. Plagioclase
b. Olivine, augite, hornblende, biotite
c. Orthoclase, muscovite, quartz
d. b and c but not a

Plagioclase

Which of the following minerals would NOT be likely to occur in rhyolite?
a. plagioclase feldspar
b. orthoclase feldspar
c. olivine
d. hornblende

olivine

Which of the following minerals is often found in evaporite deposits?
a. Gypsum
b. Migmatite
c. Plagioclase
d. Limonite

Gypsum

This picture illustrates
a. a disconformity
b. low-grade metamorphism
c. foliation
d. graded bedding

a disconformity

A detrital sedimentary rock composed mainly of particles greater than 2 millimeters
in diameter would be called:
a. shale
b. sandstone
c. conglomerate
d. rhyolite

conglomerate

Which of the following rocks are often non-foliated?
a. Slate
b. Fault breccia
c. Gneiss
d. Schist

Fault Breccia

Which one is the correct sequence in the conversion of shale into high-grade
metamorphic rock?
a. Olivine, augite, hornblende, biotite
b. Calcic plagioclase-sodic plagioclase
c. Gneiss-schist-slate
d. Slate-schist-gneiss

Slate-Schist-Gneiss

Strain is measured in
a. units of stress
b. units of distance
c. units of pressure
d. non-dimensional units (has no units)

no units

Most rock samples tested by the unconfined compression test fail
a. along horizontal planes perpendicular to the maximum principal stress
b. along planes inclined at an angle to the maximum principal stress
c. along one of the principal planes
d. a and c but not b

along planes inclined at an angle to the maximum principal stress

The limbs of overturned folds
a. dip in opposite directions at about the same angle
b. dip in opposite directions at different angles
c. dip in the same direction
d. form a graben

dip in the same direction

Which pair of fault types below are most similar in terms of stress orientation?
a. Normal fault, thrust fault
b. Reverse fault, normal fault
c. Reverse fault, thrust fault
d. Strike-slip fault, dip-slip fault

Reverse and thrust

The folds below are _________________ and were most likely caused by
_____________ stress.
a. anticlines and synclines; compressive
b. all anticlines; compressive
c. all synclines; shear
d. anticlines and synclines; tensional

Anticlines and syncline, compressive

The amount of damage caused by an earthquake as described by observers is
measured by the
a. magnitude
b. intensity
c. ground-motion acceleration
d. frequency

intensity

How much larger is the amplitude of ground displacement that occurs as the result of
a magnitude-7 earthquake compared to a magnitude-5 earthquake?
a. 2 times
b. 10 times
c. 32 times
d. 100 times

100 times

Which type of seismic waves are propagated through the Earth as alternate
compressions and expansions of the rock and soil?
a. P-waves
b. S-waves
c. both a and b
d. body waves

P-waves