Geology Exam 2
Select the correct description of a passive continental margin and the correct description of an active continental margin. Where is each type found?
A passive continental margin is tectonically inactive and far from plate boundaries and features a continental shelf, a continental slope, and a continental rise (from land toward the sea). An active continental margin is located along a convergent plate boundary, has a deep-ocean trench where subduction takes place, and may have evidence of an accretionary wedge or of subduction erosion.
What is nonfoliated texture? Give an example of a rock that serves as an example.
A rock with a nonfoliated texture, such as marble, does not display a layered or banded appearance.
On the HMS Challenger what was used to measure ocean depths?
A weighted overline
What feature in this image is indicated with arrow X? (Note: it is made of sediments.)
Accretionary wedge
The Atlantic Coastal Plain is underlain by a portion of which continent?
Africa
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.
What is an accretionary wedge, and how does it form?
An accretionary wedge is an accumulation of deformed, thrust-faulted sediments and scraps of ocean crust. This wedge is plastered against the edge of the overriding plate from the subducting plate.
What is a metamorphic facies?
An assemblage of minerals that form in very similar metamorphic environments
What is the significance of an unconformity?
An unconformity represents an interval of time that is missing from the rock record.
Where is the highest rate of heat flow escaping the Earth's interior?
At mid-ocean ridges
What rock would you expect to find associated with a mid-ocean ridge?
Basalt
What composition of magma is initially generated in a subduction zone?
Basaltic
Where is the thinnest continental crust in North America?
Basin and Range region
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.
How are chemical sedimentary rocks primarily identified, and how does this differ from how clastic sedimentary rocks are primarily identified?
Chemical sedimentary rocks are identified based on their compositions, whereas clastic sedimentary rocks are identified based on their particle sizes.
What type of chemical sedimentary rock is found in petrified wood?
Chert
Which of the descriptions below accurately describe the three various types of differential stress and the changes they can impart to rock bodies?
Compressional stress, which squeezes rock, generally shortens rocks horizontally and thickens them. Shear stress, which moves one part of a rock body past another, changes rock shape and can break rocks apart. Tensional stress, which pulls rock apart in opposite directions, horizontally stretches and lengthens rock bodies.
How do continental crust and oceanic crust differ?
Continental crust is thicker than oceanic crust; continental crust is less dense than oceanic crust; the oldest continental crust is older than the oldest oceanic crust; plus the continental crust is composed of a variety of rock types, whereas oceanic crust is composed of basalt and gabbro.
Which process is responsible for Earth's magnetic field? In which layer does this process occur?
Convection; outer core
Volcanic island arcs are found near which features on the seafloor?
Deep ocean trenches
Which physical property was responsible for determining how Earth materials separate into interior layers at the time of Earth's formation?
Density
________ is the angle of inclination of the surface of a rock unit measured from a horizontal plane.
Dip
is the process where calcium ions in limestone are replaced with magnesium or small amounts of iron.
Dolomitization
Why would geologic mapping be difficult in an area dominated by accreted terranes?
Each terrane is geologically distinct, but also highly deformed
What is meant by elastic rebound?
Elastic rebound refers to how the slippage along a fault (i.e., earthquake) allows the deformed rock to regain its original shape in a new location.
________ is a measurement of displacement on the fault surface.
Fault Slip
What is the term used to describe slow, gradual displacement along a fault without the accumulation of significant strain?
Fault creep
metamorphism will occur where two blocks of rock are grinding against each other.
Fault zone
Match the various grades of coal in order from lowest grade to highest grade. (Note: First refers to lowest grade and Fourth refers to highest grade.)
First (lowest grade): Peat Second: Lignite Third: Bituminous coal Fourth (highest grade): Anthracite coal
How Earth's force of gravity changes over its entire surface, if it changes?
Force of gravity is weaker at the equator than at Earth's poles because of centrifugal force created by Earth's rotation and the equatorial bulge. Force of gravity is stronger than average near the large dense rock bodies.
The continental shelf is composed of which material(s)?
High-resolution multibeam instruments
Which of the following represents the shortest division of time?
Holocene
________ metamorphism is responsible for the emplacement of metallic ore veins.
Hydrothermal
How does hydrothermal metamorphism alter saltwater and the basaltic rocks that make up the seafloor?
Hydrothermal metamorphism causes the minerals olivine and pyroxene in basalt to form new minerals, such as chlorite and serpentine. It also dissolves various ions in the hot seawater, which eventually rise along fractures and spew out on the ocean floor.
How are index minerals used to determine metamorphic grade?
Index minerals are specific minerals that form at specific temperatures and pressures.
Match the layer of Earth to the compositional materials.
Inner core − Solid nickel and iron with trace materials Asthenosphere − Ferromagnesian silicates mostly in a ductile state Continental crust − Granitic material composing the outermost layer Outer core − Liquid nickel and iron with trace materials Oceanic crust − Basaltic material composing the outermost layer
processes, such as evaporation or precipitation, can precipitate chemical sediments.
Inorganic
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.
What causes mountain formation in a continental rifting setting?
Lithospheric blocks, bounded by normal faults, tilt and rise.
What physical property of continents makes them difficult to subduct?
Low density
Which layer of Earth makes up more than 82% of the volume of the planet?
Mantle
Volcanic islands such as the Hawaiian islands form as a result of ________.
Mantle Plumes
Which layer or layers of the interior are believed to have convection cells?
Mantle and outer core
How are marble and quartzite alike, and how are they different?
Marble and quartzite are alike in that they are both nonfoliated, but they differ in that marble is composed of calcite whereas quartzite is composed of quartz.
The steepest angle of subduction of oceanic plates can be found at _______.
Mariana's Trench
______ faults are associated with ______ plate boundaries.
Megathrust; convergent
In what era is the Jurassic period?
Mesozoic
The ________ is a seismic boundary between the crust and the mantle where there is a dramatic increase in seismic wave velocity.
Moho boundary
The ________ is a newer scale that measures the total energy released during an earthquake by determining the average amount of slip on the fault, the area of the fault surface that slipped, and the strength of the faulted rock.
Moment Magnitude Scale
What are fault-block mountains?
Mountains formed through crustal extension and normal faulting
How does a monocline form?
Movement along a steep fault in basement rock pushes up a portion of the ductile rock layers above it.
If clay minerals in a sedimentary rock were buried at a depth where subsurface temperatures exceeded 200°C, which common metamorphic mineral would they become?
Muscovite
Are accurate, short-range earthquake predictions currently possible using modern seismic instruments?
No, there are currently no reliable methods available for making short-range earthquake predictions.
Which type of faulting is associated with the development of new ocean floor?
Normal Faulting
Match the fault with the appropriate stress that caused it.
Normal fault −− Tension Reverse fault −− Compression Strike-slip fault −− Shear
Distinguish between numerical and relative dates.
Numerical dates specify the actual number of years that passed since an event, whereas relative dates determine the order of events in relation to one another.
What of the below is true for oceanic ridges?
Oceanic ridge is transected along its length by transform faults at irregular intervals. Oceanic ridge winds through all of the major oceans on Earth.
Notice the part of this image labeled "continued trench rollback." What is happening in "trench rollback"?
Old, dense lithosphere sinks, creating slab suction that pulls the upper plate toward the trench.
How is triangulation method used to locate the epicenter of an earthquake?
On a map, a circle is drawn around each of three recording stations, with the radius being the distance from the station to the epicenter of the earthquake. The epicenter is located where the three circles intersect.
are tiny "seed" particles created when small sediments or shell fragments are rolled by waves in water supersaturated with calcium carbonate.
Ooids
What is an index fossil?
Organisms that were geographically widespread but limited to a short span of geologic time
How does a guyot form?
Over time, guyots lose their original shapes and sizes through the process of weathering, after moving away from their original locations over hot spots
Match the type of fossilization with the correct definition
Permineralization− organic pores are filled with precipitated minerals. Cast and mold− hollows left by dissolved fossils are filled with mineral matter. Amber encasement− tree resin is preserved, encasing insects. Trace Fossil− indirect evidence of fossil life (i.e., tracks, burrows).
What is the dominant mineral in the lower mantle?
Perovskite
What is the raw material for coal, and how does it accumulate?
Plants are the raw material for coal; to form coal plants must accumulate in oxygen deficient swamp water.
What are slickensides?
Polished and striated surfaces made on fault blocks
What term applies to all of geologic time prior to the Phanerozoic eon? Why is this span not divided into epochs as is the Phanerozoic eon?
Precambrian. This time period is not divided into epochs and periods because we know much less about the history of the Earth during this eon.
How are metamorphic rocks formed?
Preexisting rock is altered through heat and pressure.
Which of the following does not contribute to destruction from seismic vibrations?
Proximity to water sources
is the process by which new mineral grains larger than the original mineral grains form as a result of metamorphic heat.
Recrystallization
What sedimentary structure(s) can you identify in the above image?
Ripplemarks
Why is conduction not an efficient way to move heat through most of the Earth?
Rocks are poor conductors of heat.
How does rock within Earth change as S waves pass?
Rocks within Earth are displaced up and down as S waves pass.
Where is the thickest continental crust in North America?
Rocky Mountains
How are S waves and vertical surface waves different?
S waves are body waves, whereas vertical surface waves are surface waves. The amplitude of S waves does not decrease with depth, but the amplitude of vertical surface waves does decrease with depth.
Why do we believe Earth's outer core is a liquid?
S waves do not travel through the outer core. P waves slow down and refract at the boundary between the mantle and the outer core.
What degree of foliation is exhibited by the metamorphic rock in the image above?
SLaty
____ rock units are most useful when mapping structures like anticlines and synclines.
Sedimentary
How does the volume of sedimentary rocks in Earth's crust compare with the volume of igneous and metamorphic rocks?
Sedimentary rocks represent 5 to 10 percent of the crust, whereas igneous rocks and metamorphic rocks combined represent 90 to 95 percent of Earth's crust.
What is the primary method scientists use to determine the layering of the interior of the Earth?
Seismic waves
How does strain differ from stress?
Strain is the change in rock shape that results from stress, which is the force that deforms the rock.
________ is the compass direction of the line produced by the intersection of an inclined rock layer with a horizontal plane.
Strike
How does water get from the surface to the middle of the mantle?
Subducting oceanic lithosphere
Which factor(s) will most influence the depth of deep-ocean trenches?
Temperature and density of the plate
Match the type of stress to the correct definition.
Tension − forces pull apart from each other. Compression − forces move toward each other. Shear − forces slide past each other.
Which of the examples below shows how carbon moves from the geosphere directly to the atmosphere?
The burning of fossil fuels (e.g., coal) releases carbon dioxide directly into the atmosphere.
What is diagenesis?
The changes that convert sediments to sedimentary rocks after deposition
What is the relative movement along a strike-slip fault? SELECT ALL THAT APPLY.
The dominant displacement is parallel to the strike of the fault. Both blocks of rock move horizontally past each other
How are hypocenters and epicenters related?
The hypocenter is the exact point underground along a fault where the slippage of the two blocks of rock occurs. The epicenter is the point on Earth's surface that is directly above the hypocenter.
How are Earth's inner core and outer core similar to and different from each other?
The inner core and outer core are both composed mainly of an iron-nickel alloy. However, the outer core is liquid, whereas the inner core is solid
The inner core is believed to rotate independently from the outer layers of Earth. Why is this possible?
The inner core is separated from the mantle by the liquid outer core and can spin freely.
How do the locations of the magnetic poles change through time?
The magnetic north pole varies somewhat from the geographic North Pole while still remaining in the Northern Hemisphere. Additionally, periods of full magnetic reversals have occurred where magnetic north and magnetic south have switched places with each other. Both types of variation are caused by changes in the convection patterns within the outer core.
What is the source of flood basalts associated with oceanic plateaus?
The melting of the head of a mantle plume
Why is the moment magnitude scale favored over the Richter-like scale for large earthquakes?
The moment magnitude scale measures the total energy released, whereas the Richter-like scale only measures the amplitude of the largest seismic wave.
How might a numerical date for a layer of sedimentary rock be determined?
The order of occurrence of the sedimentary layer is related to a local igneous body that has been radiometrically dated, thus yielding an age range for the sedimentary layer.
What is the definition of a parent rock?
The rock that was altered by metamorphism
Which of the choices below accurately describes Earth's mantle from top to bottom?
The upper mantle contains the lithospheric mantle, the asthenosphere, and the transition zone; the lower mantle is Earth's thickest layer and is made of perovskite; the D" is the lowest mantle layer that is rather weak.
Generally speaking, how does the chemical composition of most metamorphic rocks compare to that of the parent rock?
Their chemical compositions are nearly the same.
Why do seismic waves follow strongly curved paths as they move through the interior?
Their velocities are changed because of increasing pressure with depth.
How do slaty cleavage, schistosity, and gneissic textures differ from each other?
These textures differ in that rocks with slaty cleavage break across their layers; rocks with schistosity exhibit layered structures of thin, platy minerals; and rocks with gneissic texture have a solid, banded appearance.
A ________ forms when a rising mantle plume causes the overlying crust to dome and separate into three rifts.
Triple Junction
Approximately 75 percent of the planet's landmasses are covered by sedimentary and sedimentary rocks.
True
Due to their size, stream gravels need a swift current to be transported, whereas sands need a current with less energy.
True
Most faults are locked in place, except for brief, abrupt movements when sudden slippage produces earthquakes.
True
Which of the following would be the most unstable during an earthquake?
Unconsolidated sediments
Which of the following best describes a seismic gap?
Unusually quiet zones along typically active faults
Where do valleys tend to form in a landscape?
Valleys form where rock layers are easily erodible (soft).
Which of the following methods of transportation will result in the best degree of sorting?
Wind
What is a suture?
Zone where two continents are welded together
What is a seismograph?
an instrument used to record earthquake waves
The limbs of an anticline will have dip angles pointing ___
away from each other
What is foliation?
banding in metamorphic rocks that results from the reorientation of minerals
A ________ marks the end of one episode of sedimentation and the beginning of another
bedding plane
A(n) ________ facies is associated with a high-pressure, low-temperature environment.
blueschist
Which type of force is responsible for reverse fault formation?
compressional force
How does heat flow through the outer core?
conduction and convection
What mechanisms of heat operate inside Earth?
conduction, which is when heat flows through a material convection, when hot materials displace cool materials (or vice versa)
What are three major features of a passive continental margin?
continental rise continental shelf continental slope
What causes melting of material under divergent plate boundaries?
decompression of rock
What are the three major topographic provinces of the ocean floor?
deep-ocean basins oceanic ridges continental margins
What are the four agents that drive metamorphism?
directional stress, pressure, heat, and chemically active fluids
The slippage of an earthquake starts ________.
focus or hypocenter
A ________ will form as sediment collects between the accretionary wedge and the volcanic arc.
forearc basin
The principle of ________ states that organisms succeed one another in a definite, determinable order that can be used to recognize a specific time period.
fossil succession
What is a fault?
fractures along which rocks move
What would you call a granite that has undergone metamorphism and now exhibits foliation?
gneiss
Evaporites, such as _____
gypsum and halite, form when minerals that were previously dissolved in water are deposited as the water evaporates
Folds form in ________ temperature-________ pressure environments.
high-; high-
What is the single most common and characteristic feature of sedimentary rocks?
horizontal strata or beds
Which rocks does contact metamorphism create? PLEASE SELECT ALL THAT APPLY.
hornfels quartzite marble
What is the agent of hydrothermal metamorphism?
hot, ion-rich water
Which option below lists the grades of metamorphism that might be encountered moving west to east from Ohio to the crystalline core of the Appalachians?
low grade, then intermediate grade, then high grade
Faults form in ________ temperature-________ pressure environments.
low-; high-
Where is hydrothermal metamorphism common?
mid-ocean ridges
Which factors influence the amount of destruction that seismic vibrations cause to human-made structures?
nature of the ground underneath human-made structuresduration of the vibrations
How does a sheeted dike complex form?
new dikes intrude older dikes, which are still warm and weak
What two types of faults are common at divergent plate boundaries?
normal and transform faults
Faults that exhibit both dip-slip and strike-slip movement are called ________ faults.
oblique-slip
The same type of stress that creates anticlines and syncline in some rocks will create ____ faults in rocks that exhibit brittle deformation.
reverse and thrust
Which type of force is responsible for normal strike-slip formation?
shear force
Which of the three basic types of seismic wave is likely to cause the greatest destruction to buildings?
surface waves
What are the two primary types of waves generated by earthquakes?
surface waves and body waves
Which of the following would be the best to use to compare large earthquakes around Earth?
the moment magnitude scale
What is the goal of correlation?
to gain a more comprehensive view of the geologic history of a region
What are the four major features of a subduction zone?
volcanic arc, deep-ocean trench, forearc, back-arc
What is the difference between terrane and terrain?
"Terrane" describes a crustal fragment consisting of a distinct and recognizable series of rock formations that has been transported by plate tectonic processes, whereas "terrain" describes the shape of the surface topography.
Which mountain range consists of the youngest collisional mountains on Earth?
Himalayas
Which orogeny is largely responsible for creating the modern Rocky Mountains?
Laramide Orogeny
Which type of volcanic material will dominate the eruptions along a continental volcanic arc?
Lavas of intermediate or felsic composition
How do mountainous regions experience gravitational collapse?
Mountains that have risen to extreme heights experience ductile spreading at depth and normal faulting as well as subsidence in the upper, brittle portion of Earth's crust.
What do mud cracks and ripple marks indicate about the geologic past?
Mud cracks indicate that the sediment was deposited in an area that was alternately wet and dry, whereas ripple marks indicate that the sediment was deposited by directional currents in water or air.
Which best describes the unique and varied bedrock geologic history of the northwest coast of North America?
Multiple terranes accreted onto the continental crust.
Which of the following is associated with a passive continental margin?
No tectonic boundaries nearby
Submarine volcanoes, called ________ may rise hundreds of meters above the surrounding seafloor.
Seamounts
What is the definition of subduction erosion?
Sediment and rock are scraped off the bottom of an overriding plate and transported into the mantle by a descending plate.
A soft, porous rock made up almost entirely of the hard parts of microscopic marine organisms is ________.
Chalk
Which of the following is not a possible mechanism contributing to continental rifting?
Changes in gravitational attraction of the moon
contain large quantities of preexisting sedimentary and crystalline rocks that have been faulted and contorted into a series of folds.
Compressional Mountains
How are breccia, conglomerate, sandstone, and shale different?
Conglomerate and breccia are both composed of gravel-sized grains. Grains are rounded in conglomerate and angular in breccia. Sandstone is composed of sand-sized rounded grains. Shale consists of grains not identifiable without a great magnification.
According to the plate tectonics model, most global mountain ranges are associated with which kind of plate boundary?
Convergent
Along which tectonic boundary are deep-ocean trenches found?
Convergent
Which of the following statements best characterizes the geology and structure of the Appalachian Mountains?
Sedimentary strata folded at in the late Paleozoic Era
What is an accretionary wedge?
Sediments and ocean crust fragments being scraped off of a subducting plate
Contrast spontaneous subduction with forced subduction.
Spontaneous subduction, which occurs at Mariana-type subduction zones, takes place when old, dense lithosphere subducts beneath the other plate at a very steep angle. In contrast, forced subduction, which occurs at Peru-Chile-type subduction zones, takes place when hot, low-density lithosphere subducts beneath the other plate at a shallow angle because of compressive forces.
Which of the following is believed to be responsible for uplifting southern Africa 1,500 meters higher than what would be expected for a stable continental platform?
Superplume
What kind of stress would be affecting the marked region in this image?
Tension
How do back-arc basins form?
Tensional stresses resulting from slab suction stretch this part of the crust, causing it to thin vertically.
What happened when the spreading center that generated the Farallon plate collided with the North American plate?
The spreading center ultimately subducted beneath the coast of California. This event destroyed this spreading center and replaced it with a transform fault system.
The Cascadia subduction zone off the coast of Washington and Oregon famously lacks a well-defined deep-ocean trench. Why might this be the case?
There is a shallow angle of plate subduction, as well as large quantities of sediment infill.
What does the presence of mudcracks indicate about the paleoenvironment?
There was a wet environment that is drying up
As India is colliding with Asia, the margin of Asia is experiencing significant deformation. What is happening to the rocks that are being deformed?
They are being displaced to the southeast to make up Southeast Asia
Which of the following best explains why some fault-block mountains have an elevated topography?
Thinning of the lithosphere resulted in upwelling of hot mantle rock and greater lithospheric buoyancy
Volcanic activity in the early history of the Earth is believed to be responsible for much of the CO2 found in the atmosphere.
True
While lithosphere is being created at the mid-ocean ridge, it is also being destroyed at the subduction zone, thus Earth remains the same size. TrueFalse
True
What is a black smoker?
a particle-filled cloud resulting from metallic-rich solutions gushing form the seafloor into the ocean water
A(n) ________ forms when sediments from the ocean floor and pieces of oceanic crust are scraped from a subducting oceanic plate and adhere to an overriding tectonic plate.
accretionary wedge
Which seafloor mapping method can map the largest extent of seafloor in the shortest amount of time?
satellites with radar altimeter
How does formation of fault-block mountains differ from the processes that generate most other major mountain belts?
Fault-block mountains form by the lithosphere rising because of hot mantle rock upwelling below that area, whereas most other mountains form by the convergence of two lithospheric plates.
Where do most divergent boundaries originate?
within continents
What are the four stages of the evolution of an ocean basin from first to last?
(1) The upper crust is broken along normal faults while the lower crust is deformed by ductile stretching; (2) tension pulls apart the crusts and crust slab sink in the middle, forming a rift valley; (3) continued spreading creates a narrow sea; (4) after continued spreading, an ocean and ridge system are created.
A divergent boundary will be characterized by what feature?
A rift zone
The largest of the shields is the ________ shield.
Africa
Which U.S. region is made up of a series of high-angle normal faults producing nearly parallel mountain ranges?
Basin and Range Province
Thermal springs known as ________ are often associated with oceanic ridges, where hot water containing dissolved minerals gushes from the seafloor.
Black Smokers
Which of the following locations displays a triple junction that resulted from a rising mantle plume?
Eastern Africa/Arabian Peninsula
Because North America continues to collide with the Eurasian plate, the Appalachians are still actively forming. TrueFalse
False
Because massive submarine structures such as seamounts and ridges exert stronger than average gravitational attraction, they produce depressed areas on the ocean's surface. TrueFalse
False
Graded bedding will display particles that are fine near the bottom of the layer and get progressively coarser toward the top.
False
In what ways are the Sierra Nevada and the Andes ranges similar?
The Sierra Nevada range exhibits evidence of Andean-type mountain building with the range's placement along an active continental margin, the Sierra Nevada Batholith that is a remnant of a continental volcanic arc, and the Coast ranges that represent either an accretionary wedge or a past island arc offshore.
Which of the processes listed below would transform an exposure of granite in the mountains into sedimentary rocks?
The granite would mechanically weather into small particles, which would travel down the slope of the mountain via mass wasting, be deposited, and undergo diagenesis when the sediments are buried under younger layers of rock.
A mountain range with peaks as high as 14,000 feet above sea level has formed. As time passes, erosion wears down the mountains. How will isostacy affect the crust?
The mountain range will rise
What is the primary reason for the elevated position of the oceanic ridge system?
The oceanic lithosphere at the ridge is hotter than the older lithosphere that is farther from the ridge. Because the hotter lithosphere at the ridge is less dense than the cooler lithosphere farther away, lithosphere is more elevated at the ridge, sinking as it cools while moving away from the ridge.
Why does the East Pacific Rise lack a rift valley?
The rate of seafloor spreading at the East Pacific Rise is very fast.
Why is the Hudson Bay region slowly uplifting?
The region is experiencing isostatic uplift after having been covered by thick glaciers.
How can satellites orbiting Earth determine features on the seafloor without being able to directly observe them beneath several kilometers of seawater?
The satellite measures the variation in the sea-surface elevation by bouncing microwaves off of the water's surface, which mimics the shape of the seafloor.
Although many areas of the continental shelves are relatively featureless, there are some locations on the shelves that have received extensive glacial deposits and significant dissection by streams. How would this have been possible?
The sea level dropped during the last glacial episode because water was stored in large ice sheets, exposing the shelves.
Match the features of a subduction zone with the manner of formation.
back-arc region - where pyroclastic materials and sediments eroded from landmasses collect on the opposite side of the island from the trench. forearc region - where pyroclastic materials and sediments eroded from landmasses collect between the island arc and the trench. volcanic arc - partial melting of subducting plates create magma, which rises to the surface Fold-and-thrust belt− mountainous zone resulting from the deformation of thick sequences of shallow marine sedimentary rocks. deep ocean trench - where the subducting slabs of oceanic lithosphere descends into the asthenosphere.
The measurement of ocean depth and the topography of the ocean floor are known as
bathymetry
Which of the choices below correctly describes three common cements in sedimentary rocks and the ways of identifying them?
calcite (which effervesces in dilute acid), silica (which produces the hardest sedimentary rocks), and iron oxides (which give rocks a reddish color
Fold-and-thrust belts are the result of ________ stress whereas fault-block mountains are the result of ________ stress
compressional; tensional
In oceanic-continental convergence, a volcanic arc is created on the ________ and is the result of ________ rising up from a subducting plate.
continental plate; magma
Which type of plate boundaries is most directly associated with Earth's major mountain belts?
convergent boundary
What are the four layers of oceanic crust from top to bottom?
deep-sea sediment, pillow lavas, sheeted dike complex, gabbro
Which type of subduction would result in tensional forces at a subduction zone?`
subduction of an old, dense plate
What is orogenesis?
the collection of processes that produce a mountain belt
When do new oceans form?
when a continent is broken apart by a divergent boundary
What data provided information about the existence of different zones within Earth?
P-wave and S-wave arrival times
What happens during radioactive decay?
Parent isotopes turn into daughter isotopes.
Which type of fault has NO vertical motion of rocks associated with it?
strike-slip fault
Which type of force is responsible for normal fault formation?
tensional force
The inner core and outer core are both composed mainly of an iron-nickel alloy. However, the outer core is liquid, whereas the inner core is soli
the Farallon Plate
What is the scientific definition of half-life?
the amount of time over which the number of parent isotopes decreases by half
What is metamorphic grade?
the degree to which a parent rock changes during metamorphism
What are rocks below and above a fault called?
the footwall below and the hanging wall above
What conditions favor the preservation of an organism as a fossil? PLEASE SELECT ALL THAT APPLY.
The organism is rapidly buried. The organism has or is made of hard parts
When going from a 5 to a 6 on the Richter Scale, what is the increase in amplitude of seismic waves?
10 times
A container holds 100 atoms of an isotope. This isotope has a half-life of 1.5 months. How many total atoms will be in the container after 3 months?
100
Propagation of fault slip occurs at a rate of about ________ per second.
2 to 4 km
A container holds 100 atoms of an isotope. This isotope has a half-life of 1.5 months. How many atoms of the radioactive isotope will be in the container after 3 months?
25
What remains after a sample undergoes two half-lives?
25 percent of the sample is composed of parent atoms, and 75 percent of the sample is composed of daughter atoms
What is the average increase in temperature along the geothermal gradient in the upper crust?
25°C per km
For what time span does radiocarbon dating apply?
70,000 years ago or younger
Why is it difficult to assign a numerical age to a sedimentary rock?
A radiometric date taken from a grain within a detrital sedimentary rock only gives the age of that one grain, which likely came from a source different from the other grains within the rock.
How are reverse faults different from thrust faults? In what way are they similar?
A reverse fault is steeper than a thrust fault; thrust faults have dips that are lower than 45 degrees. Both reverse and thrust faults result from compressional stress.
What is an earthquake?
A sudden shaking of the ground that is caused by the rapid release of energy from the slipping of crustal blocks along a fault.
What is a mineral phase change?
Atoms in a mineral are rearranged into a denser and more stable structure.
Where do body waves and surface waves travel?
Body waves travel within Earth, and surface waves travel along Earth's surface.
Which or statement or statements correctly describe brittle deformation and ductile deformation?
Both brittle deformation and ductile deformation are permanent. Brittle deformation describes a rock breaking as a result of stress, whereas ductile deformation describes a rock bending or folding as a result of stress.
What do vertical and horizontal surface waves have in common?
Both waves travel along Earth's surface and decrease in amplitude with depth below the surface.
What are the textures of clastic and nonclastic sedimentary rock?
Clastic rock consists of different discrete fragments cemented together. Nonclastic rock consists of patterns of interlocking crystals.
Which of the following groups contains all three major topographic provinces oceanographers use to define the seafloor?
Continental margins, mid-ocean ridges, and deep-ocean basins
Which part of a passive continental margin is built up by repeated deposition from turbidity currents?
Continental rise
Match the heat transfer mechanisms to the correct description of how heat is transported in or from the Earth.
Convection − warm, low-density materials rise and cool, high-density materials sink. Conduction − heat flows between two materials in contact with each other. Radiation − heat is transported away from Earth and into outer space.
Which of the following textural terms describes when minerals form a pattern of interlocking crystals in a nonclastic chemical sedimentary rock
Crystalline
The ________ layer is thought to have large variations in composition as well as temperature.
D"
Which of the following statements is true about erosion?
Erosion varies from place to place.
Which tectonic plates are responsible for the majority of seismic activity in the Alpine-Himalayan Belt, extending through the Mediterranean Sea and through the Himalayas?
Eurasian, African, and Indian plates
Which ship was involved in the first global, comprehensive study of the Earth's oceans starting in 1872?
H.M.S. Challenger
Movements along normal faults can produce alternating upthrown and down-dropped fault blocks. What are the names associated with these blocks, respectively?
Horsts and grabens
How do seismologists create long-range earthquake predictions?
Identifying seismic gaps
In the list below, indicate in which of the environments fossilization is likely to occur. Note that fossils contain organic matter.
In a floodplain The ocean floor Swamp
Name two types of body waves.
P waves and S waves
Where are the youngest rocks in a structural basin found?
In top view, the youngest rocks of a basin are near the center of the basin. he youngest rocks of a basin are on top of all the other rock layers.
What is isostasy, and what does it indicate about a floating object that has a weight added or removed?
Isostasy is the concept that Earth's crust is floating within the mantle in gravitational balance. Thus, if weight is added, the crust would sink until it reached a new isostatic balance. Conversely, if weight is removed from the crust, it would rise until it reached a new isostatic balance.
If the outer core is cooler than the inner core, why is it in a liquid state?
It is under less pressure than the inner core
What does "-zoic" in the eras of the geologic time scale refer to?
Life
How are the long-range forecasts of earthquakes useful?
Long-range forecasts of earthquakes provide important guides for building codes so that structures such as buildings, dams, and roadways can be built to withstand expected levels of shaking.
Why do geologists believe the inner core is solid?
P waves refract at the boundary between the outer core and inner core.
What kind of temperature and pressure conditions will exist in a burial metamorphism environment?
Low temperature and low pressure
Assuming your S-P interval was 10 seconds and the maximum amplitude of the largest wave on the seismogram was 20 mm, what is the magnitude of this earthquake?
M 4.3
The oceanic crust is composed almost entirely of ________ rocks that are underlain by ________ rocks, which makes up the lithospheric mantle.
Mafic;ultramafic
Liquefaction − seismic energy transforms stable soil into mobile material incapable of supporting buildings. Landslide − mass movement of material downslope, shaken loose by seismic events. Seiche − rhythmic sloshing of water in lakes and enclosed basins. Tsunami − large ocean waves generated. Subsidence − collapse and lowering of the land surface.
Match the seismic hazard with the correct definition.
Metamorphism means "a change in form." How a rock may change during metamorphism?
Metamorphism may change the mineralogy, texture, and/or chemical composition of a rock.
Where are most modern divergent plate boundaries found?
Mid-ocean Ridges
Of the three mechanisms of heat transfer, which is the only one that does not operate in the interior of Earth?
Radiation
How do rocks within Earth change as P waves pass?
Rocks within Earth both expand and contract as P waves pass.
Match the rock with the appropriate category of sedimentary rock.
Sandstone −− Detrital Sandstone − Detrital Chert −− Chemical Chert − Chemical Shale −− Detrital Shale − Detrital Bituminous coal −− Organic Bituminous coal − Organic Rock salt −− Chemical Rock salt − Chemical Coquina −− Chemical
________ are fragments of preexisting materials that have been broken down through the processes of weathering.
Sediments
By what process do sediments become well sorted, and by what process do sediments become poorly sorted?
Sediments that are transported for a long, sustained time tend to become well sorted, whereas sediments that are transported over a rather short period of time tend to be poorly sorted.
Which of the following statements about seismic wave ray paths is most accurate?
Seismic waves move along curved ray paths because the properties of materials in the Earth change.
How could you test whether the core of another planet were completely solid?
Set off a bomb to create seismic waves. If S waves arrive on the opposite side of the planet, then the core is solid.
Compaction will be the most significant lithification process for which of the following rocks?
Shale
Which of the following rocks composed of silt- and clay- sized particles displays fissility?
Shale
Which of the following can be a parent rock for gneiss?
Shale, granite, schist, and phyllite
metamorphism will occur when high-speed projectiles strike the Earth's surface.
Shock
Which of the following lists of metamorphic rocks places the rocks in order from lowest metamorphic grade to highest?
Slate, phyllite, schist, gneiss
How are a slow spreading center such as the Mid-Atlantic Ridge and a fast spreading center such as the East Pacific Rise different from each other?
Slow spreading centers have prominent ridges and rugged topography; fast spreading centers have rather smooth topographies. Slow spreading centers tend to have developed rift valleys; fast spreading centers often lack rift valleys.
What are the three compositionally distinct layers of Earth's interior?
a strong, rocky crust at Earth's surface, a hot, pressurized mantle beneath the crust, and an iron-rich core that is made of a solid inner core and a liquid outer core
A ________ is a crustal fragment that has been transported by plate tectonics and has adhered to an overriding plate
Terrane
Two containers hold the same radioactive isotope. Container A contains 1000 atoms, and container B contains 500 atoms. Which of the following statements about containers A and B is true?
The rate of decay of atoms (half-life) in container B is the same as the rate of decay of atoms (half-life) in container A.
Which of the following best describes the general relationship between the velocity of seismic waves and depth in Earth?
The velocity of seismic waves generally increases with depth.
The first sign of a tsunami's approach is a rapid retreat of water from the shoreline.
True
How do chemical weathering and the formation of biochemical sediment remove carbon from the atmosphere and store it in the geosphere?
When carbon dioxide in the atmosphere combines with water, it creates carbonic acid, which precipitates and chemically weathers the rocks on Earth. The result of this weathering is bicarbonate, which ultimately ends up in the oceans and is used by marine organisms to make their shells. When these organisms die, their skeletons settle to the ocean floor and eventually become a rock layer containing the carbon dioxide.
The white granite of the Idaho Batholith near Boise, Idaho, contains dark gray xenoliths of metamorphic material. Which is older? How do you know?
Xenoliths; the principle of inclusions
Can parent rock features such as sedimentary structures and fossils survive low-grade metamorphism?
Yes, they can, because such features can withstand low temperatures and pressures but will be destroyed in higher metamorphic grades.
What is a tsunami?
a large ocean wave generated when a megathrust fault suddenly lifts a slab of seafloor
Which of the choices below lists the successive stages in coal formation from first step to last?
accumulation of plant remains, peat formation, lignite formation, bituminous coal formation, anthracite coal formation
Which type of plate boundary is associated with regional metamorphism?
continental-continental convergent boundary
One-third of Earth's mass comes from ______.
core
The Moho separates the ______.
crust and mantle
According to the animation, what are the four primary zones in Earth's interior?
crust, mantle, outer core, inner core
The Black Hills of South Dakota is a good example of which type of geologic structure?
dome
In order of longest to shortest, what are the four basic units that make up the geologic time scale?
eon, era, period, epoch
What were sources of Earth's original internal heat?
kinetic energy from impacts during the formation of Earthradiogenic heat released during the decay of short-lived isotopes
What are the three broad categories of sedimentary environments with an example of each?
marine environments, such as deep ocean floors; continental environments, such as deserts; transitional environments, such as tidal flats
How will foliation in continental metamorphic rocks formed during subduction be oriented?
perpendicular to the direction of plate movement
Which of the following describes the type of deformation experienced by rocks before an earthquake?
slow deformation
Do metamorphic rocks look like the preexisting rock from which they form?
sometimes, but not always
The Modified Mercalli scale is ________.
still used today by the U.S. Geological survey to gather data from those who felt an earthquake
