Geology Lecture Test 3

Back-arc basins form because A. The subduction of old oceanic lithosphere may make the volcanic arc move toward the trench and produce an extensional back arc basin behind the arc B. The subduction of old oceanic lithosphere may produce less erosion in the volcanic arc and the lack of sediments will produce a low area--a basin--behind the arc C. The subduction of young oceanic lithosphere can push the fore-arc basin upward causing a new basin to form behind the arc D. The scraping of sediments and other material off the subducting ocean lithosphere is deposited in a basin located behind the trench

A

How do continental mountains and oceanic ridges differ? A. Oceanic ridges are generally wider than continental mountains B. Continental mountains are generally wider than oceanic ridges C. Continental mountains generally are much higher than oceanic ridges D. Oceanic ridges generally are much higher than continental mountains E. Continental mountains generally are composed of piles of basins while oceanic ridges contain folded sedimentary rocks

A

The measurement of ocean depth and the topography of the ocean floor are known as ________. A. Bathymetry B. Geophysics C. Seismic tomography D. Topographic surveying

A

What are fault-block mountains? A. Mountains formed through crustal extension B. Mountains that form by erosion of streams C. Mountains consisting of exposed batholiths D. Mountains formed through folding and thrusting of the crust

A

What is a significant difference between a slow-spreading ridge and a fast-spreading ridge? A. A slow spreading ridge will be narrower than a fast-spreading ridge because the slow-spreading ridge will cool closer to the source of heat that made it buoyant B. A slow spreading ridge will be wider than a fast spreading ridge because it stays close to the heat source longer and therefore is hotter than the fast spreading ridge C. A slow spreading ridge is higher than a fast-spreading ridge because more magma can flow under the slow spreading ridge D. A slow spreading ridge will be lower than a fast spreading ridge because the slow spreading ridge will be hotter and less viscous

A

What is infiltration? A. Water soaking into the ground B. Plants taking in water C. The transition from liquid to gas as a result of increases in temperature D. Water running off the surface and entering a channel Submit

A

What is the definition of orogenesis? A. Processes that collectively form a mountain belt B. Subduction of an oceanic plate beneath a continental plate C. Emplacement of metallic ores via hydrothermal metamorphism D. Ionic exchange between calcium and oxygen

A

Which of the following choices represents a rate of seafloor spreading commonly associated with a ridge such as the Mid-Atlantic Ridge? A. 1-5 cm/yr B. 1-5 km/yr C. 1-5 m/yr D. 1-5 mm/yr

A

Which of the following features are not found at mid-ocean ridges? A. Deep submarine trenches B. Shallow depths than deep ocean plains C. Basaltic lava eruptions emitted along the ridge D. Thin layers of sediments

A

Which of the following is not an example of a continental rift? A. Appalachia, United States B. Rhine Valley, Europe C. East Africa D. Lake Baikal, Siberia

A

Which of the following locations is a remnant of a forearc basin? A. Great Valley, CA B. Death Valley, CA C. Lake Baikal, Siberia D. Snake River Plain, ID

A

Which of the following statements best characterizes the Valley and Ridge Province of the Appalachian Mountains? A. Sedimentary strata folded at in the late Paleozoic Era B. Deeply eroded, late Mesozoic upwarping mountains C. Continental volcanic chain along a subduction zone D. Fault-block mountains developed from rifting of North America from Africa

A

Which of the following will mark the furthest extent of a continent? A. The lowest part of the continental slope B. The shoreline C. The crest of the continental slope D. Tidal flats exposed during low tide

A

Which style of convergent boundary will characterize an Andean-type mountain building event? A. Where oceanic lithosphere subducts beneath continental lithosphere B. Where oceanic lithosphere subducts beneath oceanic lithosphere C. Where continental lithosphere subducts beneath oceanic lithosphere D. Where continental lithosphere subducts beneath continental lithosphere

A

________ accounts for greater ocean depths moving away from the oceanic ridge toward the deep ocean basin. A. Thermal contraction B. Mantle plume C. Thermal expansion D. Convection

A

________ is the downslope movement of rock, regolith, or soil under the direct influence of gravity. A. Mass Wasting B. Weathering C. Dissolution D. Erosion

A

Which one of the following would most likely be covered with thick turbidite layers?

A deep-sea fan at the base of a continental slope

The collision of Africa and North America produced the ______ Mountains

Appalachian

A ________ is a crustal fragment that has been transported by plate tectonics and has adhered to an overriding plate. A. Xenolith B. Terrane C. Terrain D. Guyot

B

A stream is cutting into a valley wall. Which of the following is the most likely trigger for a mass-wasting event? A. The stream will deposit extra sediment on the slope, increasing the weight on the slope B. The stream erodes the toe of the slope, which results in the slope becoming over-steepened C. The stream will saturate the slope and generate a mudflow D. Upslope trees will be removed, reducing slope strength

B

Match the type of motion with the correct definition. Fall A. Mass movements in which there is a distinct plane of weakness between the slide material and underlying stable material B. Detached material moves in a free-fall C. Material moves downslope as a viscous fluid

B

Match the type of motion with the correct definition. Flow A. Mass movements in which there is a distinct plane of weakness between the slide material and underlying stable material B. Material moves downslope as a viscous fluid C. Detached material moves in a free-fall

B

Thermal springs known as ________ are often associated with oceanic ridges, where hot water containing dissolved minerals gushes from the seafloor. A. Geysers B. Black smokers C. Hot springs D. Ophiolites

B

What is the definition of a turbidity current? A. Focused jet of water blasting across the shelf from a surface stream B. Submarine landslide C. Subsidence of the seafloor D. Fast-moving water created by density differences

B

What is the geologic definition of a stream? A. A river of water that carries large volumes of water and has many tributaries B. A channelized body of water flowing down gradient C. A large lake system D. A stagnant body of water with little current and low oxygen content

B

What is the main source of magma for sea floor spreading? A. Magma from subducted material along a convergent plate boundary rises along the axis of the ridges because it is more buoyant than the cool atmosphere B. The separation of plates along the divergent boundaries reduces the pressure on the underlying mantle to produce decompression melting of some of the mantle material C. The separation of plates along a divergent boundary produces frictional heating of the underlying rocks and thus forms a magma that rises along the ridges D. A transform boundary produces frictional heating of the underlying rocks and thus forms a magma that rises along the ridges

B

What is the source of magma necessary for seafloor spreading? A. Subduction B. Decompression melting C. Partial melting D. Mantle plumes

B

What kind of subduction occurs when younger, warmer, less-dense lithosphere dips under another plate at shallower angles because it is too buoyant to sink? A. Mantle plume subduction B. Forced subduction C. Spontaneous subduction D. Overriding subduction

B

Where do "black smokers" form on the seafloor? A. They form above the rising magma along an oceanic ridge before the basalt flows onto the seafloor due to the heat from the magma B. They form above fractures in the seafloor where seawater that has circulated through the warmer parts of the lithosphere rising C. They form along seamounts because of the volcanic activity associated with the seamount D. They form near trenches where bending of the lithosphere causes heat to rise along fractures

B

Where do rift valleys form along the oceanic ridge system? A. Along the flanks of the ridge where the slope levels out to meet the seafloor B. Along the axis of some ridge segments where the rift is down-faulted C. Acting as a valley trending from the ridge peak to the seafloor D. Transecting the ridge where transform boundaries exist

B

Which factor exerts the greatest control over the velocity of debris flows and the distance they will travel? A. Slope angle B. Water content C. Friction D. Vegetation

B

Which of the following locations would be most likely to see large-scale, rapid mass wasting? A. Florida Everglades B. Rocky Mountains C. Central Illinois D. Mojave Desert

B

Which of the following scenarios best describes the creation of the lahars associated with the eruption of Mt. St. Helens in 1980? A. Ash deposited during the eruption was remobilized by a flood years later B. The volcanic dome exploded, depositing fine ash in the Toutle River C. Hot gases melted the volcano's snowcap, generating meltwater that mixed with ash D. A volcanic flank collapsed in a landslide, which flowed into Spirit Lake

B

Which of the following scenarios will be able to maintain the steepest angle of repose? A. Dry silt B. Dry sand C. Moist, clay-rich shale layers D. Wet sand-silt mix

B

Which of the following terms describes the increasing downward force on basal rocks as a mountain continues to grow? A. Accretion B. Gravitational collapse C. Isostacy D. Delamination

B

Which orogeny is largely responsible for creating the modern Rocky Mountains? A. Nevadan Orogeny B. Laramide Orogeny C. Alleghanian Orogeny D. Taconic Orogeny

B

Which type of plate boundary is associated with most of Earth's major mountain belts? A. Divergent B. Convergent C. Transform D. Mountain belts are associated with all types of plate boundaries

B

Why does subduction erosions occur? A. Because the overriding plate at a subduction boundary scrapes the material material off the downgoing plate B. Because the down-going plate at a subduction boundary scrapes material off the overriding plate C. Because submarine canyons move turbidites from the overriding plate into the trench D. Because submarine canyons move turbidites from the downgoing plate into the trench E. Because the subduction zone is growing smaller because it has encountered a continental margin

B

Why is the composition of some of the magma in volcanic arcs different from that in oceanic ridges? A. Oceanic ridges are formed by decompression melting, and volcanic arcs are not decompressing melting B. Magma differentiation at the base of the arc crust produces a magma that is light enough to rise into the crust but has a more felsic composition than that found in ocean ridges C. The mantle beneath the arc is lighter because it has more silicon and oxygen than the mantle below a ridge D. The magmas from a volcanic arc and an ocean ridge are basically the same

B

Why are debris flows more common in a relatively dry climate than in a wet climate?

Because there is less vegetation and water from the occasional storms tend to stay near the surface in dry climate

A piece of gravel is resting on a slope. Which of the following best describes how the gravitational force pulling the gravel downward will vary with the inclination of the slope? A. Gravitational force will increase as the slope angle decreases B. Gravitational force will only change with the addition of water C. Gravitational force will decrease as the slope angle decreases D. Gravitational force is not affected by the slope angle

C

According to the plate tectonics model, most global mountain ranges are associated with which kind of plate boundary? A. Divergent B. Transform C. Convergent

C

How can subduction result in the emplacement of batholiths? A. Pillow basalts get subducted with plate and forced into overriding plate B. Decompression melting of the plate creates magma C. Partial melting of the subducting plate creates magma D. Friction of descending plate creates magma

C

How is the depth of an ocean trench related to the age of the subducting ocean lithosphere at the trench? A. Older ocean lithosphere has more sediment so it clogs the system and creates a shallow trench B. Older ocean lithosphere is thicker than younger ocean lithosphere so it is harder to bend and thus forms a shallower trench than younger lithosphere C. Younger lithosphere is hotter and more buoyant so it tends to stay more horizontal and make a shallower trench than older lithosphere D. Subducting young lithosphere is rougher than subducting old lithosphere so young lithosphere will erode the overlying plate when it is subducted making a deeper trench than when old lithosphere is subducted

C

How will channel velocity change along the longitudinal profile of a stream? A. Velocity will start high and gradually decrease toward the mouth due to increasing discharge downstream B. Velocity will remain constant for the entire length of the stream C. Velocity will start low and gradually increase toward the mouth due to increasing discharge downstream

C

How would the angle of subduction of a tectonic plate influence the location of a volcanic arc? A. The shallower the angle, the closer the arc would form to the trench B. The angle of subduction doesn't affect the location of the volcanic arc C. The steeper the angle, the closer the arc would form to the trench

C

Match the type of motion with the correct definition. Slide A. Detached material moves in a free-fall B. Material moves downslope as a viscous fluid C. Mass movements in which there is a distinct plane of weakness between the slide material and underlying stable material

C

Submarine canyons found cutting into the continental shelf and slope are believed to have been created ________. A. By tectonic rifting B. By subduction C. By rivers during the ice age D. By scouring by coastal glaciers

C

The ________ describes the path water takes as it moves between the land, the ocean, and the atmosphere. A. Matter State Cycle B. Rock Cycle C. Hydrologic Cycle D. Oxygen Cycle

C

The ________ is an elevational point that divides an entire continent into large drainage basins. A. Sediment production zone B. Appalachian Mountains C. Continental Divide D. Watershed

C

What causes "spontaneous subduction?" A. Meteorites B. Earthquake activity C. Density D. Divergence

C

What is the fastest form of mass wasting? A. Slump B. Slide C. Rockfall D. Creep

C

What percentage of the Earth's surface consists of deep-ocean basins? A. 10% B. 49% C. 30% D. 37%

C

Which mountain range consists of the youngest collisional mountains on Earth? A. Grand Tetons B. Andes C. Himalayas D. Appalachians

C

Which of the following best explains why some fault-block mountains have an elevated topography? A. Large volumes of rock were thrust on top of the area B. Subduction folded and uplifted the mountain ranges to extensive heights C. Stretching and thinning of the lithosphere allowed for it to sit higher on the mantle D. Flood basalts stacked up in the region

C

Which of the following locations is composed largely of accreted terranes? A. Illinois B. Colorado C. California D. Hawaii

C

Which of the following regions of a subduction zone are characterized by thick sequences of relatively undeformed sedimentary rocks? A. Transform fault B. Suture C. Forearc region D. Volcanic island arc

C

Which of the following tectonic boundaries is associated with an active continental margin? A. Transform B. Divergent C. Convergent

C

Which type of volcanic material will dominate the eruptions along a continental volcanic arc? A. A mix of rhyolitic and basaltic materials B. Rhyolitic lavas and pyroclastic materials C. Andesitic lavas and pyroclastic materials D. Basaltic lavas

C

________ occurs when a rock is gradually dissolved by flowing water. A. Quarrying B. Abrasion C. Corrosion D. Exfoliation

C

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? A. Nothing will change the elevation of the area B. The mountain range will be depressed C. The surrounding landscape will rise D. The mountain range will rebound

D

A(n) ____ is an accumulation of sediments scraped from a subduction oceanic plate A. Deep-sea fan B. turbidite C. sea drift D. accretionary wedge E. Tectonite

D

A(n) ________ is a sequence of layers composing the oceanic crust that includes sheeted dikes, basalts, and gabbro. A. Flood basalts B. Passive margin C. Lithospheric sheeting D. Ophiolite complex

D

The sub-ducting oceanic lithosphere has about the same density as the mantle material it is sinking through. Why does the oceanic lithosphere continue to sink? A. It is being pushed by the rising magma at the oceanic ridges B. It has inertia and so it keeps sinking even though it may be more buoyant than the mantle it is sinking through C. It contains iron and is being pulled by Earth's magnetic field D. The olivine in the lithosphere converts to a high density phase at about 400 km and that acts like a weight on the end of the plate to continue to pull it downward E. The lithosphere only sinks until its density matches that of the surrounding material. When it is achieved the lithospheric plate begins to melt and rise back towards to surface of the ridge

D

Volcanic islands such as the Hawaiian islands form as a result of ________. A. Rifting B. Subduction C. Batholith emplacement D. Mantle plumes

D

What is the angle of repose? A. The angle of the slip plane from a slide B. The angle of an inclined rock layer measured from a horizontal line C. The angle of plunge into the interior D. The steepest angle at which a material remains at rest

D

What is the crescent-shaped mark found at the top of a slump block? A. Overburden B. Earthflow C. Ditch D. Scarp

D

What is the longitudinal profile? A. The slope of the stream channel from headwaters to the mouth B. The cross-sectional area perpendicular to the direction of flow C. The probability of a specific stream discharge occurring in a given year D. The cross-sectional area from the headwaters to the mouth

D

What is the slowest form of mass wasting? A. Slump B. Debris Flow C. Earthflow D. Creep

D

What kind of subduction occurs when old, dense lithosphere sinks into the mantle by its own weight? A. Mantle plume subduction B. Overriding subduction C. Forced subduction D. Spontaneous subduction

D

Which of the following best describes the effect of convective flow on the elevation of Earth's major landforms? A. Subduction of oceanic plates disrupting the convective flow on the mantle, resulting in hot spots burning through the crust B. Rotation of convecting mantle material smoothes out wrinkles in the surface C. Convective flow adds more material to the base of the lithosphere, making it downwarp D. Hot rising material upwards the landscape whereas downward flow causes downwarping

D

Which of the following particle sizes is most likely to make up a stream's suspended load? A. Gravel B. Clay C. Sand D. Silt

D

Which of the following statements best characterizes the geology of the Pacific coastal regions of western North America up into Alaska? A. Metamorphosed accretionary wedges B. Collision of a massive subcontinent of old igneous and metamorphic rocks, resulting in fold-and-thrust mountains that are still growing C. Divergent rifting creating deep, wide valleys with grabens D. Geologically distinct, microcontinent-sized fragments and terraces accreted to the continent

D

Why are abyssal plains more extensive on the floor of the Atlantic than the floor or pacific? A. Because there are only 2 small plate boundaries on the Atlantic while the Pacific has many plate boundaries B. Because the plate boundaries on the Atlantic are mostly deep trenches that rapidly fill with flat layers of sediment C. Because the Pacific seafloor has more divergent boundaries that give rise to high mountains than the Atlantic seafloor D. Because pacific seafloor has more convergent boundaries where sediments are removed and volcanic seamounts and islands is more common than in Atlantic E. Because the Atlantic seafloor has fewer earthquakes to cause faulting and disruption of the sedimentary layers that cover both the Atlantic and Pacific

D

Why are oceanic ridges high while the surrounding ocean floor is relatively deep? A. Magma from the asthenosphere pushes the upward when they erupt B. Convergence of the two plates across the ocean ridges forces them upwards C. The ridges are less dense than sea-water because they are heavy and so they will float upward. D. The ridges are less dense and thus more buoyant than surrounding ocean floor because the ridges are hot and the surrounding ocean floor is cool E. The surrounding ocean floor is thicker than the ridges so it sinks deeper into the asthenosphere

D

________ contain large quantities of preexisting sedimentary and crystalline rocks that have been faulted and contorted into a series of folds. A. Fault block mountains B. Mid-ocean ridges C. Submarine trenches D. Compressional mountains

D

Because massive submarine structures such as seamounts and ridges exert stronger than average gravitational attraction, they produce depressed areas on the ocean's surface True/False

F

Continental shelves on active margins are larger and broader than those on passive margins. True/False

F

Mudflows are big enough to move independently of the topography. True/False

F

Slow forms of mass wasting such as creep and solifluction are considered slow because they are restricted to gentle slopes and cannot achieve the same velocity. True/False

F

Consider a weathered rock or soil particle lying on a slope. How will the gravitational force pulling the particle downward along the land surface vary with the inclination of the slope?

It will decrease as the slope angle is lessened

What causes a lahar?

Lahars are always caused by unstable layers of ash and debris on the side of a volcano

Solidifuction is a form of mass wasting that occurs primarily in which type of region?

Permafrost

Abyssal plains are flat areas of the ocean floor that are likely the most level places on Earth. True/False

T

Creep is the most widespread mass-wasting process. True/False

T

Rockfalls are the primary way in which talus slopes are built and maintained True/False

T

Solifluction is a slow type of mass wasting that moves at a rate of a few centimeters per year. True/False

T

Solifluction occurs during the warmer months of the melt season. True/False

T

Why is the topography elevated in the Basin and Range Province in the western United States according to one common hypothesis?

Tensional forced caused thinning of the lithosphere in the western US which then resulted in decompression melting in the mantle and the rise of magma

Why are fold and thrust belts associated with continent-continent collisions more commonly than other types of collisions?

The continents are too buoyant to subduct so all of the material on their margins get compressed and folded during the collision and exposed around the suture zone

How did Tibet form during the Himalayan orogeny?

Tibet is a fragment or terrane that was accreted to Eurasia prior to the collision of India

Why is building on permafrost a serious problem in places like Alaska?

buildings tend to insulate and warm the permafrost causing the top part to melt and become swampy

What type of plate boundaries is associated with most of Earth's major mountain belts?

covergent

Which of the following are recognizable features of an area that might be prone to rock slides?

downward tilted rock layers with clay and a stream at the base of the slope

What is the main controlling factor in mass wasting?

gravity

Which of the following types of particles would have the greatest angle of repose?

large, angular unconsolidated particles

______ is a type of mass movement that is characterized by rotational movement along an accurate (concave) slip plane

slump

What is the relationship between the time of uplift of a region and the general character of the landscape?

the younger times of uplift are associated with more rugged topography than the older uplifted regions

What is the most common characteristic of passive continental shelves?

they are mostly flat

Which one of the following is an example of an isostatic movement?

uplift of areas recently covered by thick, continental ice sheets