Test 4 Geology
Why are urban areas susceptible to flash floods?
A high percentage of the surface area is covered with cement, asphalt, and other impervious materials
Glacier
A mass of glacial ice that forms on land and shows evidence of movement. or A thick mass of ice that originates on land from the accumulation and recrystallization of snow.
horn
A pyramid-like peak formed by glacial action in three or more cirques surrounding a mountain summit.
hanging valley
A valley left by a melted tributary glacier that enters a larger glacial valley above its base, high up on the valley wall.
What is the difference between capacity and competence?
Capacity is the maximum load of solid particles a stream can transport per unit of time, whereas competence is a measure of a stream's ability to transport particles based on size rather than quantity.
________ 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
Which of the following locations is a likely place to find a braided stream?
Flowing from the terminus of a glacier
Under what conditions will the front of a glacier remain stationary?
Glacial fronts remain stationary when melting and snow accumulation are equal.
How does a glacier lose ice through sublimation?
Ice changes from solid to gas.
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 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 statements is true?
Low gradient is associated with deposition.
Which of the following scenarios represents the best nonstructural approach to flood control?
Managing a floodplain to limit development in sensitive areas
Which of the following budget scenarios describes a glacial advance?
More ice and snow accumulates than melts each year.
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.
How does an end moraine form?
Pieces of rock are transported to the front of a glacier as ice within the glacier moves.Will plucking occur if a glacier is NOT advancing?
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.
In general, how do the channel width, channel depth, flow velocity, and discharge change between the headwaters and the mouth of the stream?
The channel width, channel depth, flow velocity, and discharge all increase as the stream approaches the mouth.
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.
base level
The lowest point to which a stream can erode
What is a floodplain?
a flat surface next to a river channel
ice sheet
a large, massive glacier that moves independently of the topography.
valley glacier
a long, narrow glacier that flows downslope.
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
three mechanisms by which streams erode
abrasion, corrosion, quarrying
Which type of channel (bedrock or alluvial) will have meandering streams?
alluvial
What is the term for sediment deposited by streams?
alluvium
which way does a retreating glacier go?
always downhill
cirque
an amphitheater-shaped basin at the head of a glaciated valley produced by frost wedging and plucking.
Particles moving by saltation are transported in the _______ load.
bed
A(n) ________ flood will occur when an engineered structure fails and releases large quantities of stored water.
dam-failure
Select all those properties from the list that INCREASE as you move downstream in a river.
discharge and velocity
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
What are water gaps?
erosion through hills or ridges caused by a change in base level
How do fjords relate to glacial troughs?
fjords are glacial throughs that become 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
delta
form where streams enter large lakes or oceans.
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
A(n) ________ stream is a stream that is in equilibrium and is neither eroding or depositing material, but simply transporting it.
graded stream
Select from the list all those items that DECREASE as you move downstream in a river.
gradient and channel roughness
In which part of a stream's course would one typically find bedrock channels?
headwaters
The body of ice covering Greenland is called a(n):
ice sheet
A(n) ________ flood is most often associated with northward-flowing rivers in the Northern Hemisphere because the upstream stretches of the river will thaw before the downstream.
ice-jam
Where do glaciers form?
in places where more snow falls in the winter than melts away in the summer
Glacial stagnation
incoming ice is equal to ablation.
glacial retreat
incoming ice is less than ablation.
Which type of glacial movement will be responsible for the greatest amount of glacial flow?
internal flow
what happens to the grain size as you get farther down the alluvial fan?
it increases
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
Which of the following is a characteristic of a graded stream?
meanders and well developed flood plain
zone of accumulation
more snow falls than melts, top of glacier
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
__________ are defined as a chain of glacial lakes where each lake flows into the next.
pater noter lakes
The Great Flood of 1993 in the Upper Mississippi River basin is an example of which type of flood?
regional flood
esker
sands and gravels
outwash plain
sands and gravels
Ice shelves are grounded in ________ and float in ________.
shallow water; deep water
Which of the following particle sizes is most likely to make up a stream's suspended load?
silt
bar
small deposits that form in the stream channel.
laminar flow
smooth, not turbulent
arete
solid rock
erratic
solid rock
Alluvial fans occur where a _____ exits the _____ and enters the _____.
stream; mountains; basin
What is the snowline?
the elevation above which snow persists throughout the year
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
Imagine a valley containing four stream terraces. Where would the youngest stream terrace be found?
the lowest terrace
What is the zone of wastage?
the part of a glacier where snow melting exceeds snow accumulation
drumlin
till
end moraine
till
What is the best way to describe the shape of a glacial valley?
u-shaped
Which choice below is a type of glacier?
valley glacier, piedmont glacier, ice cap, ice sheet
Which of the following is a characteristic of a graded stream? CHOOSE ALL THAT APPLY.
well-developed floodplain, meanders
How does an oxbow lake form?
when a meander gets cut off from the rest of the river
glacial advance
when accumulation exceeds ablation
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
Which part of a glacier will see the build-up of ice and snow over the course of a full year?
zone of accumulation
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
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.
Name the 2 main types of glaciers:
Valley (Alpine) glaciers and ice sheets
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.
snowline
________ is an elevation point above which snow remains throughout the year.
piedmont glacier
a broad lobe that spreads out to flow on an open plain.
What is a stream's longitudinal profile?
a cross-sectional view of a stream from the headwaters to its mouth