Geology Exam 2

If a 50-year flood occurs on the Mississippi River this year, what is the probability that a flood of the same magnitude will occur in the following year?

2%

Sea level is currently rising at 3.3 mm/year, and scientists predict that global warming could cause a rise in sea level of 7 m if left unabated. How long will it take the sea to rise 7 m at the current rate?

2,121 years

What is the average percentage of dissolved salt in seawater?

3.5%

Approximately what percentage of the Earth's surface is covered with ocean water?

70%

The figure below shows two hypothetical streams that have identical cross-sectional areas but different channel shapes. Assuming all other factors are equal, stream ________ will have the fastest flow because of the difference in ________.

A; wetted perimeter

Which river has the greatest discharge of any stream on the Earth?

Amazon

For several generations, your family has lived on a farm with a water well. There has never been a problem with the water supply in the past; however, your well has now gone dry. There are several small farms nearby and a large, growing city 50 miles to the north. What can you conclude is the most likely reason for your well to become dry?

As the city grew larger, more wells were drilled and water was overpumped, thus lowering the water table.

In the figure below, where would be the best place to locate a well that would supply the most water?

B

In the figure below, which letters represent the wave height and wavelength?

B and E

In the figure below, which letters represent the crest and trough?

C and D

Imagine you have a layer of limestone with high porosity but low permeability. What can you do to increase its permeability to allow water to be pumped from the layer and used as a source of drinking water?

Drill down to the layer and set off explosives in the hole to fracture the rock.

Using the figure below, which of the following lists correctly identifies the seafloor landforms G, C, and F?

G = abyssal plain, C = mid-ocean ridge, F = trench

In many areas with karst terrain, people use sinkholes as places to dump garbage. What effect might this practice have on the groundwater supply?

It could contaminate the groundwater in unconfined aquifers only.

Which of the following is true of beach nourishment as a solution to coastal erosion?

It is costly and may only provide a temporary solution.

You have a choice to drill your water well into a shallower unconfined aquifer or a deeper confined aquifer. Drilling deeper will cost more money; however, you choose to drill into the confined aquifer. Why?

The confined aquifer will most likely have a higher water quality.

The porosity of vesicular basalt is about 25%; however, when water is poured on it, the water does not come out the other side. How is this possible?

The vesicles in basalt are not connected, so it has no permeability.

Why is the surface salinity in the tropics so much higher than that of the equator or high latitudes?

There is a higher evaporation rate in the tropics.

What will eventually happen to the headlands in the figure below?

They will become a straight line of cliffs as rock is eroded away.

Consult the figure below. If someone were to dump chemicals into a dry river, what would happen to those chemicals?

They would end up flowing with the groundwater toward the city's wells.

What physical property of the underlying rock would lead to the formation of a cliff over which a waterfall may form?

a high resistance to erosion

You are running a sonar survey to map the bathymetry of an ocean basin. Using the following continuous sonar data giving the depth of the seafloor in meters, what feature have you just discovered?

a mid-ocean ridge

You are drilling a water well when you hit water at a much shallower level than you expected. What have you likely found?

a perched aquifer

All else being equal, water will flow faster in a stream with ________ and a ________ wetted perimeter.

a straight channel; small

Which type of coastline would most likely contain estuaries or fjords?

a submergent coastline

A stream carrying sediment flows over the solid rock of its channel, polishing the rock and wearing it away. This is an example of __________.

abrasion

A coast that grows seaward as a result of regular sedimentation is a(n) __________

accretionary coast.

Urbanization of a watershed is most likely to result in __________.

an increase in the volume of water entering streams after rainfall

For a well to function properly, it must be drilled below the water table and into a(n) _________.

aquifer

An impermeable layer of rock or sediment is a(n) ________.

aquitard

If an intrusive igneous rock is unfractured, it serves as a(n) ________ in local hydrogeology.

aquitard

Structures—like jetties, groins, and breakwaters—that are designed to prevent beach erosion __________.

are a temporary solution that decreases the rate of beach erosion

Major oceanic surface currents travel ________.

at an angle to prevailing winds as a result of the Coriolis effect

The lowest elevation to which a stream can downcut is the ________.

base level

The form and topography (depth profile) of the ocean floor is termed ________.

bathymetry

Why is a spring tide so much higher than a normal high tide?

because the Sun is aligned with the moon

In some cases, the push of flowing water can break chunks of solid rock off of the channel bed. These pieces are then carried along by a stream as _________

bedload

Hard water results from relatively high concentrations of dissolved ________.

calcium and magnesium

Which of the following is NOT true? A 100-year flood ________.

cannot occur in successive years

Surface currents flow __________ in the Northern Hemisphere and __________ in the Southern Hemisphere.

clockwise; counterclockwise

A(n) __________ is a vegetated, flat-lying stretch of coast that floods at high tide, becomes particularly exposed at low tide, and does not feel the impact of strong waves.

coastal wetland

Swamps and marshes are examples of __________.

coastal wetlands

Thermohaline circulation carries ________ water from the poles to the equator, where the water becomes ________.

cold; warm

The capacity of a stream depends on its __________.

competence and discharge

Braided streams ________.

consist of a series of intertwined channels that are overloaded with sediment

The shallowest portions of an ocean found along the margins of continents are the ________.

continental shelves

Which portion of the seafloor is most steeply sloped?

continental slopes

The outer edge of a meander, where material is being eroded, is a(n) ________.

cut bank

The density of seawater increases with ________ temperature and ________ salinity.

decreasing; increasing

In uniform sediments with a relatively constant and gentle slope at the surface, a ________ drainage network is expected.

dendritic

The figure below shows an example of a ________ drainage network.

dendritic

Compared with the continental crust, the oceanic crust is ________.

denser

A flowing artesian well is one that ________.

discharges groundwater at the ground surface without pumping

Running water dissolves soluble minerals. This material is most likely to be transported by a stream as _________.

dissolved load

A coastline characterized by steep-sided cliffs and associated with an active margin is likely to be __________.

emergent

When the sea level rises, an ocean may invade a river valley, producing a nearshore body of water of mixed and variable salinity termed a(n) ________.

estuary

The flat-lying area surrounding a river channel is termed the ________.

floodplain

Rip currents ________ the shoreline.

flow directly away from

Longshore currents ________ the shoreline.

flow parallel to

A stream is ________.

flowing water confined to a channel

Pirate streams ________.

form when headward erosion causes one stream to intersect another

The slope of a stream surface measured between two points along its course is the ________.

gradient

Runoff from farm fields entering a stream system is likely to be __________ than that from naturally vegetated fields.

greater and more sediment-laden

As a rule, groundwater always flows from areas of ________.

greater hydraulic head to those of lesser hydraulic head

Because of wave refraction, erosion along an irregular coastline is ________.

greatest along headlands

The majority of liquid freshwater within the Earth exists in ________.

groundwater

The water table surface mimics the topography in an area because ________.

groundwater flow rates are so low

The major surface currents on Earth that display a circle-like path and follow the ocean basin margins are known as __________.

gyres

Meandering streams ________.

have a channel that is highly sinuous (curvy)

Ephemeral streams ________.

have flowing water either episodically or during only a portion of the year

Water in a stream flows from its _________ to its __________.

headwaters, mouth

An aquifer has ________ porosity and ________ permeability.

high; high

Unfractured vesicular basalt has ________ porosity and ________ permeability.

high; low

High tide during a full moon will be ________.

higher than normal

The region below a streambed where groundwater flows in the same direction as the stream but at a slower rate is termed the ________ zone.

hyporheic

A coral reef would MOST likely be found

in the shallow waters surrounding a tropical volcanic island.

The discharge of a river traveling through a temperate region will typically ________ downstream; the discharge of a river traveling through an arid region will typically ________ downstream.

increase; decrease

Along beaches, groins have ________.

increased erosion rates immediately down-current from the groin

The stream gradient of most rivers ________.

is greater near the source than near the mouth

The majority of caves are formed by the dissolution of bedrock ________.

just below the water table

You have been given the extraordinary opportunity to take Alvin (a submersible) down into the Atlantic Ocean to examine how the seafloor sediments have changed throughout geologic history. Which of the following locations would yield the most information?

just off the coast of North America

Topography dominated by depressions formed by the collapse of caves is termed a ________.

karst landscape

The sea surface salinity is ________ at the mouth of the Amazon River and ________ in the Dead Sea.

low; high

Rates of groundwater flow are ________ than stream flow because the water ________.

lower; must make its way through tiny pore spaces

Pumping vast quantities of water locally ________.

lowers the local water table, forming a cone-shaped depression

V-shaped stream valleys result from the downcutting of stream erosion and ________.

mass wasting on the valley sides

If a material is porous, it ________.

may be permeable or impermeable

The elevation of the water table ________.

may rise during rainy periods and sink during droughts

If a material is highly permeable, it ________.

must either have substantial porosity or be fractured

At the equatorial ocean basins, sea surface temperatures may reach 25°C or greater. What is the range of temperatures for the seafloor, approximately 4−5 km below?

near freezing (1°C−2°C)

Runoff is NOT commonly derived from ________.

ocean currents

Within a meander, where is sediment most likely to be deposited?

on the inner banks of the meander

A meander that is cut off to become completely isolated from the main channel but which retains water is a(n) ________.

oxbow lake

Along a uniform and steep slope of relatively weak substrate, a ________ drainage network is expected.

parallel

The figure below shows an example of a ________ drainage network.

parallel

Which type of drainage network is associated with badlands topography?

parallel

Material through which water readily flows is termed ________.

permeable

The inner edge of a meander, where sediment is deposited, is a(n) ________.

point bar

Land subsidence is likely when ________.

pumping lowers the water table

Along a large cone-shaped volcano, a ________ drainage network is expected.

radial

The figure below shows an example of a ________ drainage network.

radial

In a region with prominent orthogonal sets of joints, a ________ drainage network is expected.

rectangular

The figure below shows an example of a ________ drainage network.

rectangular

Waves ________.

refract so as to impact the shore in a nearly parallel manner

The base level of a tributary would ________ if a dam and a reservoir were constructed where it flowed into a trunk stream.

rise

A "bird's foot" delta configuration, similar to that of the Mississippi River delta, forms when the ________.

river current exceeds the oceanic current

Ultimately, the base level of a stream valley cannot be lower than ________.

sea level

Which of the following features is characteristic of a rocky coast?

sea stacks

The dissolution of rock produces ________.

secondary porosity

Which of the following is the BEST example of an organic coast?

shallow coral reef

Any place where groundwater naturally flows out of the Earth's surface is termed a(n) ________.

spring

Notice the newly constructed seawall in the illustration below. The most likely outcome of its construction is that the seawall will __________.

temporarily protect the cliff from beach erosion

The deepest part of a curved stream channel, where the flow is fastest, is called the ________.

thalweg

The distinction between a valley and a canyon is ________.

that the sides of a canyon are more steep than those of a valley

Porosity is best described by which of the following?

the amount of open space in a rock or sediment

Which of the following is MOST likely to result in stream rejuvenation?

the base level of a stream drops

Which of the following scenarios is more likely to cause a flash flood than a slow-onset flood?

the failure of a stream channel's levees

Barrier islands are constantly moving in the direction of ________.

the longshore drift

The Coriolis effect causes the apparent deflection of currents as a result of

the rotation of the Earth.

A person is digging a hole, when the hole suddenly starts to fill with water. What have they found?

the water table

Compared with the continental lithosphere, the oceanic lithosphere is ________.

thinner

The width of the intertidal zone depends on the __________.

tidal range

In the figure below, which way is the wave moving?

to the right

The figure below shows the Dakota and Ogallala aquifers along with interlayered shale deposits. What likely occurred in the area to produce the alternating shale and sandstone layers?

transgression and regression

In a region characterized by a parallel series of ridges and valleys, a ________ drainage network is expected.

trellis

The figure below shows an example of a ________ drainage network.

trellis

The primary stream fed by tributaries within a dendritic drainage network is termed a ________ stream.

trunk

The castle on the island of Mont Saint-Michel, France, can be accessed ________ a day during ________ tide, but ________ during neap tide.

twice; low; never

A(n) ________ aquifer is more likely to be contaminated than a(n) ________ aquifer.

unconfined; confined

Rock or sediment between the water table and the land surface represents a(n) ________.

unsaturated zone

Which of the following scenarios is most likely to result in an emergent coast?

uplift associated with active margin tectonics

If a beach is in an east-west orientation and the waves are approaching the shore from the southeast, in which direction will the longshore drift be?

western

The shape of a delta is primarily determined by ________.

whether river currents or ocean currents are locally predominant