Geology exam three combined flashcard sets

What is infiltration?

Water soaking into the ground

The ________ describes the path water takes as it moves between the land, the ocean, and the atmosphere.

hydrologic style

What is the geologic definition of a stream?

A channelized body of water flowing down gradient

The ________ is an imaginary line that divides an entire continent into large drainage basins.

continental divide

Which of the following is not one of the three zones of a river system?

sediment capacity zone

Streams generally receive their water from two sources. What are those two sources?

overland flow and groundwater

What will happen to the water level in the stream if the water table falls below the level of the stream channel?

the stream will lose water to the groundwater system

Streams will tend to lengthen thanks to ________ erosion.

headward

What is the wetted perimeter of a stream?

The amount of flow in contact with the banks and bed of the channel

What is the longitudinal profile?

The slope of the stream channel from headwaters to the mouth

How will channel velocity change along the longitudinal profile of a stream? 

Velocity will start low and gradually increase toward the mouth due to increasing discharge downstream.

What is the mouth of a stream?

The location where one stream flows into another body of water

A stream's gradient is referring to the ________ of a stream.

slope

Which of the following beds would be easiest for a stream to erode?

lined with silt

Which part of a stream's sediment load moves the slowest?

bed load

________ is the maximum load of solid particles a stream can transport per unit time.

capacity

________ is a measure of a stream's ability to transport particles based on size rather than quantity.

competence

In terms of competence, if the velocity of the stream triples, the impact force of the water will increase ________ times.

nine times

During what periods would streams see the greatest erosion and transportation of sediment?

floods

) In which part of a stream's course would one typically find bedrock channels?

headwaters

A ________ stream consists of a complex network of converging and diverging channels that weave around channel bars.

braided stream

Which of the following locations is a likely place to find a braided stream?

flowing across a stream delta

When a meandering stream erodes through the narrow neck of a meander loop, it often leaves behind a quiet backwater called a(n) ________.

oxbow lake

What is base level? 24) ______ A) The downward limit of erosion B) The gradient line along the longitudinal profile of the stream C) The highest elevation streams can be found D) The transition from a straight channel stream to a meandering stream

the downward limit of erosion

A(n) ________ stream is a stream that is in equilibrium and is neither eroding or depositing material, but simply transporting it.

graded stream

________ are flat areas along streams that are created by the deposition of alluvium and is subject to periodic inundation. 

floodplains

What is a flood?

when discharge in a river exceeds the river’s capacity

A(n) ________ flood will occur when an engineered structure fails and releases large quantities of stored water.

dam-failure

Why are urban areas susceptible to flash floods?

A high percentage of the surface area is covered with cement, asphalt, and other impervious materials

Which of the following scenarios represents the best nonstructural approach to flood control?

Managing a floodplain to limit development in sensitive areas

Most mountain ranges are the result of ________ stress.

compressional

Which of the following terms describes the increasing downward force on basal rocks as a mountain continues to grow?

Isostacy

How would the angle of subduction of a tectonic plate influence the location of a volcanic arc?

The steeper the angle, the closer the arc would form to the trench

In which location on a continent would one be likely to find young mountain belts (less than 100 million years old)?

along the margins of the continent

Which of the following regions of a subduction zone is characterized by thick sequences of relatively undeformed sedimentary rocks?

forearc region

Put the four regions of a subduction zone in order from the convergent boundary landward toward the continental interior.

Deep-ocean trench, forearc region, volcanic arc, back-arc region

Which factor(s) will most influence the depth of deep-ocean trenches?

Density and composition of the mantle beneath

The Cascadia subduction zone off the coast of Washington and Oregon famously lacks a welldefined 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.

How does the angle of subduction affect the dimensions of the forearc basin?

Shallow angle of subduction leads to a wide forearc basin

What is the source of the sediments in a forearc basin?

Continental sediments and pyroclastic materials

If a back-arc basin is associated with a volcanic island arc, what tends to develop there?

Long, linear sea

If a back-arc basin is a region related to a subduction zone, how can such an extensional basin form near a boundary defined by compression?

Trench rolls back as the old, dense subducting plate sinks.

Which of the following is an example of a volcanic island arc?

Aleutian Volcanoes

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

A ________ will form as sediment collects between the accretionary wedge and the volcanic arc.

forearc basin

A divergent boundary will be characterized by what feature?

A rift zone

Which of the following locations is a remnant of a forearc basin?

Great Valley, CA

What is an accretionary wedge?

Sediments and ocean crust fragments being scraped off of a subducting plate

Which type of volcanic material will dominate the eruptions along a continental volcanic arc?

Lavas of intermediate or felsic composition

A ________ is a crustal fragment that has been transported by plate tectonics and has adhered to an overrid ing plate.

terrane

Which of the following locations is composed largely of accreted terranes?

California

What is a suture?

The zone where two continents are welded together

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 subducted into the mantle

Put the three orogenic events of the Appalachian in order from oldest to youngest.

Taconic Orogeny, Acadian Orogeny, Alleghanian Orogeny

Which of the following describes the events of the Taconic Orogeny?

The rifting of Pangaea opened the modern Atlantic Ocean

Which of the following statements best characterizes the geology of western North America, starting in California and extending through British Columbia and up into Alaska?

Geologically distinct, microcontinent-sized fragments and terraces accreted to the continent

What are fault-block mountains?

Mountains formed through crustal extension and normal faulting

Which U.S. region is made up of a series of high-angle normal faults producing nearly parallel mountain ranges?

Basin and Range Province

Which of the following is a real-world example of isostatic adjustment?

Rebound of the landmass around Hudson Bay after glacial ice sheets have retreated

Why would geologic mapping be difficult in an area dominated by accreted terranes?

Each terrane is geologically distinct, but also highly deformed

The measurement of ocean depth and the topography of the ocean floor are known as ________.

Bathymetry

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

What are the two types of continental margins?

Passive and Active

) Which of the following is associated with an active continental margin?

Convergent boundaries

Which of the following is associated with a passive continental margin?

Divergent boundaries

Which region is surrounded by an active continental margin?

Pacific ocean

Which of the following scenarios would likely result in the development of a passive continental margin?

Continental blocks rifting apart and becoming separated by seafloor spreading

The continental shelf is composed of which material(s)?

Granitic crust covered with sedimentary rocks

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

Which of the following will mark the furthest extent of a continent?

The lowest part of the continental slope

What is the definition of turbidity current?

Fast-moving water created by density differences

Which part of a passive continental margin is built up by repeated deposition from turbidity currents?

continental rise

) Submarine canyons found cutting into the continental shelf and slope are believed to have been created ________. 

by rivers during the ice age

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.

Where is the deepest place on Earth?

Challenger deep

Along which tectonic boundary are deep-ocean trenches found?

convergent

Volcanic island arcs are found near which features on the seafloor?

deep-ocean trenches

What is the source of flood basalts associated with oceanic plateaus?

The melting of the head of a mantle plume

Volcanic islands such as the Hawaiian Islands form as a result of ________. 

mantle plumes

Submarine volcanoes, called ________ may rise hundreds of meters above the surrounding seafloor.

seamounts

Where do rift valleys form along the oceanic ridge system?

Along the axis of some ridge segments where the rift is down-faulted

What rock would you expect to find associated with a mid-ocean ridge?

basalt

What generates the magma necessary for seafloor spreading?

decompression melting

Which of the following materials or features are not found at mid-ocean ridges?

Deep submarine trenches

The oceanic crust is composed almost entirely of ________ rocks that are underlain by ________ rocks, which makes up the lithospheric mantle.

mafic; utlramafic

The sheeted dike complex is layer ________ of the ocean floor.

2

Which of the following is not an example of a continental rift?

Appalachia, United States

Thermal springs known as ________ are often associated with oceanic ridges, where hot water containing dissolved minerals gushes from the seafloor.

black smokers

Which process, common near black smokers, uses hot water circulating through the crust to alter olivine and pyroxene into chlorite and serpentine?

Hydrothermal metamorphism

Why do mantle plumes tend to concentrate beneath supercontinents such as Pangaea?

A large landmass acts as an insulating blanket to trap heat in the mantle.

Which physical property was responsible for determining how Earth’s materials separate into interior layers at the time of Earth's formation?

Density

What is a mineral phase change?

Atoms in a mineral are rearranged into a denser and more stable structure.

________ is the process where materials separate into different layers due to density.

Differentiation

What is the major difference between the inner core and the outer core?

The inner core is solid while the outer core is liquid.

What is the primary method scientists use to determine the layering of the interior of the Earth?

Seismic Waves

What will happen to a seismic wave when it is reflected? 

The wave will be bounced back toward its source.

What will happen to a seismic wave when it is refracted?

The wave will be bent when passing into a material of differing density.

Which seismic waves would be most useful in determining the extent and thickness of the Earth's interior layers?

P and S waves

Which of the following materials will allow for the fastest transmission of seismic waves

Rigid, less compressible material

What is diffraction? 

A seismic wave is bent when it passes by a curved surface.