Geology Test Four Study Guide

How is "rock flour" formed?

A glacier pulverizes rocks

Why are urban areas susceptible to flash floods?

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

How does a glacier lose ice through sublimation?

Ice changes from solid to gas.

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

Graded stream

Which are part of the bed load?

Gravel / Sand

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

Headwaters

Why are researchers exploring the use of the radish as a cover crop?

It may be able to conserve most fall-applied nitrogen on the same fields where it is applied, thus preventing nutrient runoff.

How does the formation of a natural levee impact flooding?

Natural levees raise the height of the stream channel, reducing the amount of flooding that will occur on the floodplain.

Why do farmers apply nitrogen to their fields in the spring and fall?

Nitrogen provides nutrients to the plants for the coming growing season.

How many stream terraces can exist along a single valley?

No limit exists. Stream terraces will keep forming as long as lateral erosion and downcutting continue.

Why is the northern Gulf of Mexico described as a "dead zone"?

Nutrient enrichment starts a chain of events that depletes the water of oxygen, making it difficult for aquatic life to survive.

Glaciers form because of the accumulation of large amounts of ice and snow. Which of the following provides the most water needed to create glaciers?

Oceans

________ are stratified sands and gravels carried away from the glacial terminus by meltwater.

Outwash

Distinguish between outwash deposits and ice-contact deposits.

Outwash deposits are deposited by meltwater streams beyond the terminus of a glacier, whereas ice-contact deposits accumulate on, within, or immediately adjacent to a glacier.

a broad lobe that spreads out to flow on an open plain

Piedmont glacier

________ involves the removal of blocks from the bed of a stream channel.

Quarrying

Which of the following locations does not currently have glaciers?

Scotland

Are stream terraces depositional or erosional landforms?

Stream terraces can be either depositional or erosional.

What is base level?

The downward limit of erosion.

How would you expect the front of a glacier to move if it undergoes a period of net accumulation, followed by net wastage, and finally a period of net accumulation?

The glacier's front would move forward, backward, and then forward again.

Which of the following is a characteristic of glacial till?

The particles are often scratched and polished.

How would a snow line on a glacier move as a glacial front is advancing?

The snow line would move downslope.

Under what circumstances will the front of a glacier advance, retreat, or remain stationary?

The terminus of a glacier advances if there is more accumulation than ablation, retreats if there is more ablation than accumulation, and remains stationary if accumulation is balanced with ablation.

What is the best way to describe the shape of a glacial valley?

U-shaped

a long, narrow glacier that flows downslope.

Valley glacier

What is a flood?

When discharge in a river exceeds the river's capacity

Will plucking occur if a glacier is NOT advancing?

Yes, because glacial ice is still moving inside the glacier even if the glacier's front is not advancing.

Which part of a glacier will see the build-up of ice and snow over the course of a full year?

Zone of Accumulation

Snowline

________ is an elevation point above which snow remains throughout the year.

What is a stream's longitudinal profile?

a cross-sectional view of a stream from the headwaters to its mouth

What is a floodplain?

a flat surface next to a river channel

What is a stream terrace?

a remnant of an older floodplain that sits above the stream valley

What is an end moraine?

a ridge of debris deposited at the end of a glacier

What is a natural levee?

a ridge of flood deposits next to a river channel

Lateral and medial moraines are found in connection with ________ glaciation.

alpine

Which way does ice flow in a glacier retreating uphill?

downslope

Describe the erosion occurring during headward erosion

erosion backwards at the start of the stream

Levee

formed by floodwaters on either side of a stream.

Alluvial fan

formed by mountain streams emerging onto a flat plain.

During a glacial retreat, a glacier will flow _____ while the terminus moves _____.

forward; backward

In glaciated terrain, waterfalls are associated with ______.

hanging valleys

Where do glaciers form?

in places where more snow falls in the winter than melts away in the summer

Glacial retreat

incoming ice is equal to ablation

Glacial stagnation

incoming ice is equal to ablation.

Glacial advance

incoming ice is greater than ablation.

Complete this analogy: Sliding is to gravel as dissolution is to_____________.

ions

What is meant by a nonstructural approach to flood control?

limiting certain activities or land uses and implementing appropriate zoning regulations in high-risk flood areas

Characteristics of graded stream

meanders well-developed floodplain

Which landform marks the furthest extent of an advancing glacier?

terminal moraine

What is the zone of wastage?

the part of a glacier where snow melting exceeds snow accumulation

a large, massive glacier that moves independently of the topography

Ice sheet

________ is an erosional method where meltwater penetrates fractures in subglacial bedrock and freezes.

Plucking

Match the glacial landform with the material it is made of

photo on computer

Imagine a valley containing four stream terraces. Where would the youngest stream terrace be found?

the lowest terrace

Yazoo tributary

when a tributary streamenters a river valley that has a substantial natural levee and flows for many kilometers before finding an opening into the main river.

__________ are defined as a chain of glacial lakes where each lake flows into the next.

Pater noster lakes

How does an end moraine form?

Pieces of rock are transported to the front of a glacier as ice within the glacier moves.

Why would construction businesses find eskers to be economically important?

They provide easily accessible sand and gravel deposits.

Besides flood control, a(n) ________ can also be used to generate hydroelectric power. However, they are expensive to build and maintain.

dam

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

dam-failure

What are water gaps?

erosion through hills or ridges caused by a change in base level

Delta

form where streams enter large lakes or oceans.

How can pieces of rock in contact with a stream bed move?

rolling, sliding, bouncing

Alluvial fans occur where a _____ exits the _____ and enters the _____.

stream; mountains; basin

A ________ is a small, circular lake that occupies a cirque basin.

tarn

What is the snowline?

the elevation above which snow persists throughout the year

What is suspended load?

the fine-grained particles that travel in the water column above the stream bed

Which is the best definition of glacial snow line?

the line dividing zones of accumulation and melting of ice at the surface of a glacier

When do streams erode laterally?

when downcutting is occurring in easy-to-erode sediment or rock

When do stream terraces form?

when streams exist under alternating erosional and depositional conditions

What are the three main zones of a river system from highest to lowest?

zone of sediment production, zone of transportation, and zone of deposition

_______________ is/ are cheap to implement, but it/they can adversely affect property values.

zoning regulation

When was the last time North America had major ice sheets?

18,000 years ago

Which type of channel (bedrock or alluvial) will have meandering streams?

Alluvial

How does an oxbow lake form?

An oxbow lake forms when the bend of a meandering river is isolated from the river because erosional forces create a cutoff in the main river channel. This isolated bend becomes the oxbow lake.

Which two regions currently contain the world's last remaining ice sheets?

Antarctica and Greenland

__________________ confines water flow and can experience significant erosion. Constant maintenance is required.

Artificial levee

Particles moving by saltation are transported in the _______ load.

Bed

Under what conditions will the front of a glacier remain stationary?

Glacial fronts remain stationary when melting and snow accumulation are equal.

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

Capacity

Removing obstructions from a river channel is a form of a(n) _____________________ It can make a river more navigable, but may also increase bank erosion due to increased water flow.

Channelization

a small, round glacier at the head of a valley.

Cirque

Complete this analogy: Bouncing is to sand as suspension is to_____________.

Clay

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

Competence

Why have local nutrient reduction strategies been slow to be implemented?

Farming is a business and nutrient reduction likely will not occur unless there is a clear economic benefit to doing so.

From where do the majority of the nutrients found in the northern Gulf of Mexico originate?

Farms located in the American Midwest

How do fjords relate to glacial troughs?

Fjords are glacial troughs that became submerged as the ice left the valleys and the sea levels rose.

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

Floodplains

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

Flowing from the terminus of a glacier

How do natural levees form?

Levees form as the result of the repeated flooding of a river within a floodplain. Each time the floodwaters recede, the suspended load that had been carried by the water is deposited, building up levees along the banks of the river.

________ is fine silt generated by glaciers that can be carried for long distances by the wind.

Loess

Which of the following budget scenarios describes a glacial advance?

More ice and snow accumulates than melts each year.

Which of the following particle sizes is most likely to make up a stream's suspended load?

Silt

Which moraine marks the furthest extent of glacial ice?

Terminal moraine

A(n) ________ is a sharp, knife-edged ridge that forms between two valley glaciers.

arête

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

braided stream

The process that causes dissolution of limestone bedrock in a stream is ______.

corrosion