MG Ch 6 through 10
is the maximum possible damage destination on the Mercalli scale
XII
What are the features associated with a divergent boundary that is spreading quickly?
a relatively smooth swell with gentle slopes
Which of the following do all oil traps have in common?
a reservoir rock with a cap rock above it
Strike-slip faulting of the Queen Charlotte and San Andreas fault systems shows
a right lateral sense of motion
The lithosphere is defined as
a rigid layer of crustal and mantle material
A graywacke is
a sandstone with the sand grains embedded in a clay-rich matrix
What is a tsunami?
a series of water waves that travel away from a fault in all directions at high speed
When will the first earthquake waves arrive at a seismograph station?
a short time after the earthquake occurs
The distance between a seismological recording station and the earthquake source is determined from the
arrival times of P and S waves
Where are most modern divergent plate boundaries found?
at mid-ocean ridges
mudstone
clay and fine silt
shale
clay and fine silt
Which of the following climates would have the greatest degree of ice wedging?
cold in the winter, warm in the summer, and with moderate precipitation
What type of plate boundary are most tsunamis associated with?
convergent plate boundaries
The plate boundary in the U.S. Pacific Northwest is _____, while most of the California coast is characterized by a _____ plate boundary
convergent; transform
Sedimentary rocks account for about what percentage of the Earth's outermost 10 kilometers of rock (first percentage)? Also, what percentage of the Earth's continental area is covered by sedimentary rocks (second percentage)?
A. 5% & 75%
Clay minerals formed from gabbro or diorite bedrock illustrate which kind of weathering?
A. Chemical
is the most common type of chemical sedimentary rock.
A. Limestone
Abundant moisture and warm temperatures result in high rates of chemical weathering.
A. True
Calcite is the main mineral constituent of the sedimentary rock limestone and of the metamorphic rock marble.
A. True
Calcite, a major component of some monumental and building stones, slowly dissolves in weakly acidic waters.
A. True
Chemical weathering in bedrock below the land surface often begins along joints and sheeting fractures.
A. True
Feldspars commonly decompose during weathering to clay minerals, silica, and soluble constituents.
A. True
Oxidation of iron is an important chemical weathering process for ferromagnesian silicate minerals like olivine and biotite.
A. True
Removal of soluble chemical constituents from soil is termed by leaching.
A. True
Rock cleavage or slaty cleavage in slates is largely a consequence of abundant, parallel-aligned, very fine-grained mica flakes in the rock.
A. True
Sheeting is mainly a process of mechanical weathering.
A. True
Slate and schist are both derived by metamorphism of shales and mudstones.
A. True
The distinctive layers or bands of different minerals in gneisses may be complexly folded.
A. True
Three major factors involved in metamorphism are elevated temperature, elevated pressure, and the chemical action of hot fluids.
A. True
Very fine-grained, iron oxide particles account for nearly all red, yellow, and brown soil colors
A. True
Which of the following is not a type of limestone?
A. arkose
What major change occurs during metamorphism of limestone to marble?
A. calcite grains grow larger and increase in size
Which characteristic is absolutely necessary for a sedimentary rock to have potential as a possible reservoir rock for oil or gas?
A. high porosity
What platy, parallel, mineral grains are the most visual aspect of foliated metamorphic rocks?
A. micas
Which of the following sedimentary features would typically be found in shales but not in sandstones?
A. mud cracks
What type of foliation results from the parallel alignment of abundant, coarse-grained, mica flakes in a metamorphic rock?
A. schistosity
What is meant by the statement "Every metamorphic rock has a parent rock"?
All metamorphic rocks are created only through the change of preexisting rock.
Which of the following components make up a healthy soil?
All of these choices are needed.
What is a seamount?
An active volcano that occurs along the crest of the mid-ocean ridge.
sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion of granitic bedrock.
Arkosic
Humus is a concentration of decaying, organic matter in the B-horizons of lateritic soils.
B. False
Like most other liquids, water decreases in volume when it freezes.
B. False
Quartz weathers readily to aluminum-rich clay minerals.
B. False
Sheeting fractures and exfoliation domes commonly develop in areas with soft. highly fractured bedrock.
B. False
In terrain with steep hill slopes, which crop and cultivation technique will minimize soil erosion?
B. apples; land between the trees is planted in grass and not cultivated
Which one of the following is not likely to be generally associated with impact of an asteroid or large meteorite?
B. blueschists
is a strong, parallel alignment of coarse mica flakes and/or of different mineral bands in a metamorphic rock?
B. foliation
Detrital sedimentary rocks are classified (named) based on the
B. grain sizes of the detrital particles
Tektites originate in what metamorphic environment?
B. high temperatures associated with meteorite impacts
Which of the following describes a characteristic process in the formation of a pedalfer soil?
B. iron oxides and aluminum-rich clays are precipitated in the B-horizon
Why is the humus layer typically thicker in a cool, temperate, forest soil than in a tropical rainforest soil?
B. less humus is produced in the cool, temperate forest but the rate of decay and oxidation is slower than in a tropical rainforest
Which of the following best describes the conditions of contact metamorphism?
B. pressures are fairly low, the rock is in the upper part of the crust, and heat is supplied from a nearby magma body
Which term describes a soil formed by weathering of the underlying bedrock?
B. residual
Which of the following sedimentary features can each be used to determine paleocurrent directions?
B. ripple marks and cross stratification
Oolitic limestone is most likely to form in what type of depositional environment?
B. shallow, clear, marine waters with vigorous current activity
Which of the following best describes sets of fractures in relatively fresh bedrock, such as granite, that are roughly parallel to the land surface?
B. sheeting fractures
Frost wedging is the major weathering process contributing to the formation of which regolith material?
B. talus slopes
What portion of an angular, fracture-bounded granitic block shows the highest rate of weathering?
B. the edges and corners
What is the difference between a barrier reef and an atoll?
Barrier reefs surround an inactive volcano emerging above sea level, while atolls surround the previous location of a submerged volcano.
Differentiate between the formation of biochemical rocks and the formation of inorganic chemical rocks.
Biochemical rocks form from organisms that were once alive, such as limestone from marine shells, whereas inorganic chemical rocks form from non-biological processes, such as salt that is left behind when a lake evaporates.
Which of the following statements about coral reefs and seamounts is most accurate?
Coral reefs at the ocean surface grow away from seamounts over time.
If the stress applied to the rock is greater than rock strength, what happens?
Blocks of rock will slide relative to one another along a fault, causing an earthquake
Which statement regarding Baja Mexico and the city of Los Angeles is correct?
Both are located on the Pacific Plate.
is not a common cementing agent for sandstones.
C. Flourite
Which of the following best describes the "Dust Bowl"?
C. areas of severe wind erosion on the Great Plains, 1930s
What is probably the single most important, original, depositional feature in sedimentary rocks?
C. bedding or stratification
Clay minerals, silica (SiO2), and dissolved potassium bicarbonate in the soil water are products which process?
C. chemical weathering of orthoclase feldspar
Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks?
C. evaporate minerals are more soluble than calcite and quartz
In the Rocky Mountain region of the United States, north-facing slopes (downhill direction is toward the north) are typically more moist and heavily forested than south-facing slopes. Why?
C. north-facing slopes receive about the same amount of precipitation as south-facing slopes; less moisture evaporates from north-facing slopes
Which of the following statements concerning mechanical weathering is not true?
C. precipitation of iron oxides during the chemical weathering process
Which of the following lists the rocks in the order of increasing grain size and increasing grade of metamorphism?
C. slate, phyllite, schist
Overall, this type of seismic wave is the most destructive.
C. surface wave
Which of the following statements best describes erosion?
C. the process by which weathered rock and mineral particles are removed from one area and transported elsewhere
Assume that water filling a crack in a rock undergoes cycles of freezing and melting. Which of the following statements is true?
C. water expands as it freezes, causing the crack walls to be pushed apart
________ is a strong, parallel alignment of coarse mica flakes and/or of different mineral bands in a metamorphic rock.
Foliation
Which is the correct order of coral reef development near seamounts?
Fringing reef, barrier reef, atoll
Which one of the following is an important mechanical weathering process for enlarging fractures and extending them deeper into large boulders and bedrock?
Frost wedging
Why are garnets used in sandpaper?
Garnets have a value of 8 or 9 on the Mohs Hardness Scale, making them very abrasive.
The major determining factor for the chemical break down of rocks is their chemical composition. For example, granite and basalt are both igneous rocks with different chemical composition and structure and, therefore, different weathering rates. Rocks with minerals that crystallize late in Bowen's reaction series, like granite, are usually more resistant to chemical weathering than those with minerals that crystallize early, like basalt. Besides chemical composition, a secondary factor that affects the rate of weathering in such rocks is the amount of cracks/fractures present. Rank the rocks in order of the rate of chemical weathering they would experience, assuming they are all located in the same warm wet climate. Rank from slowest to fastest.
Granite, with very few or no cracks Granite, with abundant cracks Basalt with few to no cracks Basalt with abundant vesicles (holes)
is characterized by the segregation of light and dark-colored minerals into thin layers into thin layers or bands.
Granitic gneiss
Which of the following locations will weather a block of marble the most quickly?
Honolulu, Hawaii
The Mercalli Scale is a scale from
I to XII that rates the structural damage due to an earthquake
The _____ magnitude scale is a measure of energy released. It does not directly measure the extent of building damage.
Richter
Choose the most likely scenario for how this rock formed. You can infer the environmental conditions where the rock formed from the characteristics of the clasts. For example, in places where sediments are affected by high-energy waves or wind, clasts will be weathered to a similar size and thus will be well sorted. In places with quiet, calm water, small clasts like mud are most likely to accumulate in thin layers.
Rocks eroded from mountains were deposited over a short time in a dry environment, where they were buried by other sediments and cemented into rock.
P waves are small-amplitude waves that vibrate parallel to their direction of travel. The figure below shows an analogous example with a slinky
Surface waves, S waves, and P waves can all be recorded by a single seismogram. However, they show up separately on the seismograph because they travel with different speeds.
Will Sumatra experience another tsunami like the destructive one of December 2004?
This is likely, because Sumatra is near many ocean trenches
Continental crust is generally thicker than oceanic crust.
True
Earthquakes result from the sudden release of elastic strain energy previously stored in rocks surrounding a zone of fault movement.
True
Oceanic crust is mainly basaltic in composition; the mantle is more like the igneous rock peridotite in chemical composition.
True
The Richter earthquake magnitude scale is based on the total amount of energy released by the earthquake
True
The crust and mantle are solids; the inner core is thought to be solid
True
The epicenter of an earthquake is on the surface of the Earth directly above the focus
True
Tsunamis are caused by sudden displacement of large volumes of seawater.
True
Why do ships at sea tend not to notice tsunamis?
Tsunamis in deep water have small wave height and long wavelength.
Clastic sedimentary rocks are formed during a process called diagenesis. The process of diagenesis is similar for many sedimentary rock types. Here is the process described specially for the diagenesis of sand into sandstone. Imagine a large deposit of loose sand sediment along a shoreline. Over a great amount of time, the sand is compacted as more and more sand is piled on top. Greater depths increase heat and pressure, which cause the sand to cement together, and become sandstone. Over time, the material above the sandstone will be eroded, as will the sandstone. Sedimentary rocks that have clasts prone to falling off are said to be poorly cemented, while rocks with clasts firmly in place are well cemented. Sort the statements describing the clasts shown. Drag the appropriate items to their respective bins.
Understanding the clasts in this conglomerate rock is important in order to determine how this rock formed. Sediment grains that eroded from other rocks now compose the conglomerate. Over time, the clasts of this conglomerate will erode and will again be loose sediment grains. Next, you will interpret the type of environment where this rock formed.
How can the creation of ice result in physical weathering?
Water expands in volume when freezing, exerting pressure on a container.
How did weathering destroy New Hampshire's Old Man in the Mountain?
Water migrated along fractures in the rock, where it froze and wedged the rock apart.
What role does hot ion-rich water play in the process of metamorphism?
Water migrates into host rock carrying ions to stable minerals in order to facilitate growth of new metamorphic minerals.
Which of the following factors describe the metamorphic conditions in a subduction zone?
low temperature high pressure
Which of the following factors describe the metamorphic conditions at a mid-ocean ridge?
low temperature low pressure hot, watery fluids
Examine the words and/or phrases below and determine the relationship among the majority of words/phrases. Choose the option that does not fit the pattern.
manganese nodules
Which of the following contains the entire ophiolite suite, in order from the mantle to the seafloor?
mantle peridotite, gabbro, sheeted dike complex, pillow lavas, deep-sea sediments
nonfoliated metamorphic rock consisting mostly of calcite
marble
What two, metamorphic rocks are composed predominantly of single minerals?
marble and quartzite
A conglomerate is poorly sorted with well-rounded grains. This rock was likely formed in what depositional environment?
mountain stream
compaction is a very important part of the lithification process for which of the following sediments?
mud
Most of the energy used by the industrial and residential/commercial sectors is __________.
natural gas
__________ is split nearly evenly among the industrial, residential and commercial, and electric power sectors
natural gas
Which type of faulting is associated with the development of new ocean floor?
normal faulting
Most of the world's largest earthquakes happen around the rim of the Pacific Ocean. The map below shows the locations of the 15 largest earthquakes in the world since 1900. Refer to the map of Earth's plates below, and determine which type of plate boundary is most often associated with these earthquake events.
ocean-continent convergent (subduction) boundaries
Which of the following might be seen where strike-slip movement has occurred?
offset fences
foliated, fine-grained metamorphic rock formed from mudstone and shale
phyllite
On a seismogram, _____ will show the highest amplitudes
surface waves
Referring to the accompanying seismogram, which of the seismic waves had the highest amplitude when it reached the seismic station?
surface waves
Think about the soil horizons that make up the solum. Why isn't the C horizon part of the solum?
the C contains unweathered parent material
How are tsunamis generated?
through displacement of the seafloor under water
Which of the following applies to the basic constituents of halite, gypsum, and sylvite?
transported as dissolved ions; deposited by evaporation
Quartz is quite resistant to weathering and is an important components of sands in riverbeds and on beaches.
true
If all the particles in a detrital sedimentary rock are nearly the same size, it is __________.
very well-sorted
Wind-blown sand deposits would most likely be __________ and __________.
very well-sorted; well-rounded
Which of the following climates will have the highest rate of weathering?
warm, wet climates
The Earth's magnetic field originates by
weak electrical currents associated with fluid motions in the outer core
A smooth grain shaped like a cigar is __________ and shows __________.
well-rounded; low sphericitity
When do new oceans form?
when a continent is broken apart by a divergent boundary
Where do most divergent boundaries originate?
within continents
What is a seismograph?
an instrument used to record earthquake waves
P waves
are faster than S waves and surface waves
Which of the following is a temperature associated with metamorphism?
400 degrees Celsius
Almost _____ of all electric power produced relies on coal as a source of energy.
46%
Refer to the accompanying seismogram in Part A again, and determine the time interval between the arrival of the first P wave and the arrival of the first S wave.
6 minutes
Where does the clay that accumulates in the B horizon come from?
A and E horizons
What is the underlying principle of seismograph construction?
A heavy weight suspended within a moving box needs to overcome inertia, resulting in a slight delay in the motion of the weight after the box moves.
What is a tablemount?
A seamount that grew above sea level, experienced wave erosion, and is now inactive.
From the land surface downward to the unweathered bedrock, which of the following is the correct order of the different soil horizons?
A. 0, A, E, B, C, bedrock
Earth has three compositionally distinct layers—the crust, mantle, and core. The core has separate inner and outer sections that are physically different. For the following physical and compositional properties, sort each item into the bins for the layer of Earth that they best characterize. Drag the appropriate items to their respective bins.
Crust is Earth's stiff, rigid, rocky shellpart of this layer has a relatively homogeneous composition, while the other part is less uniform in composition Mantle contains a weak layer below the lithosphere contains rock rich in magnesium and iron. Core contains iron and nickel contains a liquid outer layer and a solid inner layer
Approximately how much more energy is released in a 6.5 Richter magnitude earthquake than in one with magnitude 5.5?
D. 30 times
is typically formed by metamorphism of a sandstone.
D. Quartzite
Which of the following sedimentary rocks would you expect to have originally been deposited by fast-moving streams?
D. conglomerate
Coal beds originate in
D. freshwater coastal swamps and bogs
Which one of the following is an important, mechanical weathering process for enlarging fractures and extending them deeper into large boulders and bedrock?
D. frost wedging
is a nonfoliated rock formed by contact metamorphism of a shale or mudstone.
D. hornfels
Which of the following metamorphic rocks could be used to neutralize acidic mine waters?
D. marble
What two factors speed up rates of chemical reaction and weathering in rocks and soils?
D. warm temperatures; very moist
__________ is when various geologic materials exposed to the same environmental conditions will weather differently depending on their composition.
Differential weathering
The mantle is composed mainly of metallic iron with small amounts of magnesium silicate minerals.
False
Unconsolidated, water-saturated soils or sediments provide good foundation materials for buildings and other structures.
False
Which term describes a soil formed by weathering of the underlying bedrock?
Residual
The inertia of the suspended weight causes it to not move with the rest of the seismogram. As a consequence, the attached pen scribbles back and forth on the seismograph paper in a violent fashion. The amplitude of the scribbles is proportional to the amplitude of the seismic wave and can be used to estimate the size of an earthquake. There are three types of waves that a seismogram can record: surface waves, P waves, and S waves. Surface waves have the largest amplitude because they move along Earth's surface. They can vibrate with a vertical or a horizontal motion:
In contrast, S waves and P waves travel though the ground. They can actually travel all the way through Earth's interior. S waves vibrate perpendicular to their direction of travel. The figure below shows an analogous example with a rope.
Which of the following best describes the difference between differential stress and confining pressure?
In differential stress, the stresses on the sides are greater than the force of gravity. Stresses are the same on all sides for confining pressure.
Why does the wave height of a tsunami increase as the tsunami enters shallow water?
In shallow water, the energy of the tsunami must be contained within a smaller water column
Where do coral reefs exist with sea mounts?
In tropical latitudes
cement produces bright-red and yellow colors in some sandstone.
Iron oxide
Which of the following is a true statement regarding the Farallon Plate?
It was an oceanic plate that used to exist between the Pacific and North American Plates.
Which answer correctly distinguishes among limestone, dolostone, and chert?
Limestone, which is composed of calcium carbonate, forms by both chemical and biochemical means; dolostone, which is composed of calcium-magnesium carbonate, forms strictly by chemical means; chert, which is composed of microcrystalline quartz, forms most often chemically and to a lesser extent biochemically.
refers to the tendency for a foundation material to lose its internal cohesion and fail mechanically during earthquake shaking
Liquefaction
The names given to clastic sedimentary rocks are, in large part, determined by the physical characteristics of the particle size rocks' clasts. Mud-sized clasts are very small, less than 0.06 mm in diameter. Sand grains are between 0.06 and 2 mm. Gravel (granule) has a larger range, from 2 to 4 mm. Pebbles are 4 to 64 mm. Cobbles are 64 to 256 mm. Clasts larger than cobbles are classified as boulders. Clastic sedimentary rocks can also be identified by the characteristic of clast sorting. If most of a rock's clasts fall within only one or two of the particle size classes above, the grains of the rock are said to be well sorted.
Many of the clasts within this rock are larger than sand. Many of the clasts in this rock have rounded edges.
forms from the metamorphism of limestone or dolostone
Marble
Read the following descriptions of several different environments. Based on the information given, sort each environment into the correct bin for an environment that would experience predominantly mechanical weathering or predominantly chemical weathering. Drag the appropriate items into their respective bins.
Mechanical weathering would predominate. A cold wet environment at high elevation, in which freezing and thawing is common. A cold dry environment experiencing uplift, in which material is being removed by erosion from an underlying pluton/intrusive igneous rock Chemical weathering would predominate. A hot environment with many short but intense rainstorms.A hot humid climate with heavy precipitation that occurs all year.A warm wet environment with above average yearly rainfall and several stormy seasons each year.
Which of the following describes the orientation of slaty cleavage and mineral grains in relationship to the stress applied?
Mineral grains are oriented parallel to the direction of the weakest stress applied Slaty cleavage is parallel to the direction of the weakest stress applied.
How do oceanic ridges differ from continental mountain ranges?
Most mountain ranges form through the collision of two continents, whereas oceanic ridges form when material upwells from the mantle and generates new oceanic crust.
What happens as plates diverge at an oceanic ridge?
New oceanic crust and lithospheric mantle are generated by the cooling of molten rock upwelling from the mantle.
Which soil horizon contains the greatest amount of organic material?
O Horizon
Which one of the following statements about the crust is NOT true?
Oceanic crust is enriched in potassium, sodium, and silicon.
Seismic activity from earthquakes is documented in seismograms that are recorded by instruments called seismographs. Seismographs all over the world are calibrated to record various types of seismic waves. Body waves travel quickly and are able to move through Earth's interior. There are two types of body waves: P waves (primary waves) and S waves (secondary waves). Since P waves travel faster than S waves, they will be recorded on a seismogram first, assuming the seismograph is some distance from the earthquake epicenter. The further a seismograph is from an earthquake epicenter, the greater the time between P- and S-wave arrivals. If a seismograph is at an earthquake epicenter, then P and S waves arrive at basically the same time. The other type of seismic waves, called surface waves, travel near the ground surface and are slightly slower than body waves. The amplitude of different types of seismic waves as recorded on a seismogram also varies. Amplitude is the maximum extent of vibration. P waves generally have the smallest amplitude. S waves are somewhat larger, while surface waves are much larger. The amplitude of seismic waves is related to an earthquake's magnitude and the location of the seismograph relative to the epicenter. The larger the amplitude of seismic waves from a seismograph near the epicenter, the greater the earthquake magnitude and potential for destruction. Use the accompanying seismogram to answer which of the three types of seismic waves reached the seismograph first.
P wave
Which ocean is associated with most tsunamis?
Pacific Ocean
How can plants physically weather a rock?
Plant roots exert outward pressures as they grow.
have the highest velocities
Primary waves
a common mineral found in igneous rocks, is the most abundant mineral in detrital sedimentary rocks.
Quartz
The amount of destruction caused by earthquake vibrations is affected by
all of these
Which of the following statements is correct?
S waves travel through solids and P waves travel through liquids
The _____ earthquake was accompanied by extensive fire damage
San Francisco, 1906
Why do coral reefs at the ocean surface grow away from seamounts over time?
Seamounts subside as tectonic plates move. Coral reefs grow away from the seamount in order to stay near the sunlight.
Which of the following accurately compares the Mid-Atlantic Ridge and East Pacific Rise?
The Mid-Atlantic Ridge is spreading at a much slower rate than the East Pacific Rise.
What happened to the Farallon Plate approximately 20 million years ago?
The San Andreas and Queen Charlotte Faults were established where it was subducted beneath the North American plate.
Which of the following must be true for hydrocarbons to be collected by a fault trap?
The fault must be sealed
By what process did the gabbro turn into amphibolite?
The gabbro was heated to 500 °C and buried a few miles below the Earth's surface.
The principles above all describe sedimentary rock beds. Beds is the term used for large, parallel layers of sediments. Bedding is the accumulation of numerous beds and appears like a series of stacked books. Bedding can most often be seen by viewing variations in the color and consistency of the individual layers across the outcrop. Once beds of sediment are laid down, the layers of rock can be buried and compressed. The pressure from this compression will turn the sediment to stone in a process called lithification. The original bedding of the sediments is then "locked" into the geologic record and can be seen in the resulting layers present in the rock outcrop. Choose the sketch that best represents the bedding of the Tonoloway in this outcrop
The layers of sediment in this outcropping run from the upper left to the lower right. Geologists refer to the angle of this new orientation as the dip, which is the angle of departure of the bedding from horizontal. Correctly identifying bedding in sedimentary rocks like this is very important, because beds are often used by geologists to study kinematics and other types of analyses. picture shows lines slanted to the left side.
Which of the following describes the orientation of the long axes of rocks and mineral grains in relationship to the stress applied?
The long axis of a rock is parallel to the direction of the weakest stress applied. Mineral grains are oriented parallel to the direction of the weakest stress applied.
Graphite is identified in a particular schist. Which one of the following conclusions is justified?
The pre-metamorphic rock was a shale or mudstone containing organic matter.
Both tombstones in Figure 1 are from the same cemetery and were erected within four years of each other. Why is the younger marble tombstone more weathered than the older granite tombstone?
The quartz and feldspar's in the granite are more resistant to weathering than the calcite in the marble. (also, acid {in rain} affects calcite)
Which of the following locations will weather a block of marble the most quickly?
The quartz and feldspars in the granite are more resistant to weathering than the calcite in the marble. (also, acid {in rain} affects calcite)
Which of the following must be true for hydrocarbons to be trapped by salt diapirs?
The salt must be impermeable.
Earthquakes are typically given two different sources: the hypocenter and the epicenter. As shown in the figure below, the hypocenter is the actual location where an earthquake originates, and the epicenter is the point on Earth's surface directly above the hypocenter:
The seismic waves produced by an earthquake are recorded by a device called a seismogram. Geologists can use seismogram data to locate the epicenter of an earthquake. Part A - Seismograms and seismograph data Part complete A seismogram is mounted to bedrock so that it shakes when a seismic wave passes through the area, as shown in the figure below.
Which one of the following best characterizes tsunamis?
They have relatively small amplitudes compared to their very long wavelengths
Which of the following is true regarding tsunamis?
They occur in the open ocean, wavelengths are many miles or kilometers and wave heights are only a few feet
The Richter magnitude of an earthquake is determined from the
amplitude of the surface waves
The distance between a seismic station and an earthquake can be determined by the interval between the arrival of the P wave and the arrival of the S wave, as shown in the graph below. Using the data in the seismogram in Part A and your answer to Part B, compute the distance from the seismic station to the earthquake with the accompanying travel-time graph.
about 3000 miles or 4800 kilometers
Major earthquakes are often followed by somewhat smaller events known as
aftershocks
The average composition of the oceanic crust is thought to approximate that of
basalt
The continental rise is located ________.
between an abyssal plain and continental slope
What is the main difference between a conglomerate and a sedimentary breccia?
breccia clasts are angular; conglomerate clasts are rounded
What causes melting of material under divergent plate boundaries?
decompression of rock
The hanging wall moves __________ relative to the footwall in a __________ fault.
down; normal
The mechanism by which rocks store and eventually release energy in the form of an earthquake is termed
elastic rebound
Nuclear energy is used in what energy sector(s)?
electric power
About half of renewable energy is used in __________.
electric power generation
The position on Earth's surface directly above the earthquake source is called the
epicenter
Which of the following best describes bedded gypsum and halite?
evaporates; chemical, sedimentary rocks
When a fault is expressed at the surface, it is called a
fault scarp
When an earthquake occurs, energy radiates in all directions from its source. The source is also referred to as the
focus
List the fluids commonly found in traps, from the least to most dense.
gas, oil, water
Which of the following is a metamorphic rock?
gneiss
coarse-grained, metamorphic rock with alternating bands or stringers of light and dark minerals
gneiss
What kind of metamorphic texture results in the segregation of light and dark mineral bands?
gneissic texture
Which of the following correlate to transport distance?
grain size and rounding
The average composition of the continental crust most closely approximates that of
granite
conglomerate
gravel
Fault Kinematics II
hanging wall, B = footwall, hanging wall down, normal fault
Part B - Fault Kinematics I
hanging wall, B = footwall, hanging wall up, reverse fault
Which of the following statements concerning slate is not true?
has abundant, coarse-grained mica
What is the major source of heat for contact metamorphism
heat from a nearby magma body
forms by contact metamorphism of mudstones and shales
hornfels
What is a mantle plume?
hot mantle rock rising from deep within the Earth
The name of the site where slippage begins and earthquake waves radiate outward is called the
hypocenter
Which one of the following statements concerning mechanical weathering is NOT true?
involves a major change in the mineral composition of the weather material
The dense core of Earth is thought to consist predominantly of
iron
What two layers of the ophiolite sequence are compositionally similar, but formed in different areas with respect to the crust?
pillow lavas and gabbro
Flint, chert, and jasper are microcrystalline forms of
quartz (SiO2)
sandstone
sand
The process by which mineral deposits are created through the concentration of minor amounts of metals is known as ________
secondary enrichment
Most of our knowledge about the Earth's interior comes from
seismic waves
The record of an earthquake obtained from a seismic instrument is a
seismogram
The instrument that records earthquake events is termed a
seismograph
How long does it typically take for the first earthquake waves to arrive at a seismograph that is some distance away from the epicenter after the earthquake occurs
several minutes
Which foliated rock is the lowest-grade metamorphic rock?
slate
Which low-grade metamorphic rock, composed of extremely fine-sized mica and other mineral grains, exhibits well cleavage?
slate
Which of the following metamorphic rocks would form as a result of shale undergoing low-grade regional metamorphism?
slate
A(n) __________ is not associated with structural deformation
stratigraphic (pinchout) trap
