Geology Chapter 16

What is the minimum velocity needed for a 0.8 mm sand particle transition from a state of deposition to transportation? (Q45)

5 cm/sec

What is the term for sediment deposited by streams?

Alluvium

How did the Mississippi River delta form?

As the Mississippi River enters the Gulf of Mexico, its velocity decreases and it begins to drop its sediment load.

What kind of stream channel is visible here? (Q53)

Braided channel

Which portion of the stream is the most likely to become an oxbow lake in the near future? (Q56 part D)

D

What depositional feature is visible here? (Q64)

Delta

At which of the following locations is erosion occurring? (Q56 part A) At which of the following locations is deposition occurring? (part B)

E C A B D

Point bars are locations where erosion occurs whereas cutbanks are locations where deposition occurs.

False

What kind of streamflow is present in this image? (Q23)

Laminar flow

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.

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

Overland flow and groundwater

Describe what these drainage patterns indicate about the underlying geology (Q66 part B)

Rectangular- Fractured bedrock Trellis- Alternating resistant and less resistant material that have been tilted or folded Dendritic- underlying rock is relatively uniform Radial- Topographic high in center of drainage pattern

What is the ultimate base level?

Sea level

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

Silt

What is base level?

The downward limit of erosion.

When considering the movement of water on Earth within the hydrologic cycle, which of the following choices is responsible for driving this process?

The hydrologic cycle works because water exists on Earth in solid, liquid, and gaseous states.

Streams carry most of their sediment load in the form of suspended load.

True

What is a stream's longitudinal profile?

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

Particles moving by saltation are transported in the _______ load

bed

What is the dominant fluvial process in a clear, sediment-poor stream moving down a steep slope? (Q49 part B)

downcutting

Which of the following locations contains the most water in Earth's hydrosphere aside from the oceans?

glaciers

Velocity and turbulence are _____ at the __________. (Q55 part C)

greatest; outside of a meander

Which of the following would increase flow velocity

having a narrow, deep channel

Which of the following is the primary step that allows water to enter the groundwater system?

infiltration

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

rolling, sliding, bouncing

Which of the choices below is not a factor that causes infiltration and runoff to vary from place to place and from time to time?

time of the day

Where do deposition and erosion of material occur along a meander? (Q49 part C)

Deposition occurs on the inside of the meander, whereas erosion occurs on the outside

What are the three types of loads carried by streams?

bed load, suspended load, dissolved load

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

ions

According to the hydrologic cycle, once precipitation has fallen on land, what paths might the water directly take?

runoff into a river evaporation/transpiration runoff into the sea infiltration into the ground

A stream is transporting Particle A. The velocity of stream is decreasing, but for the moment, Particle A is still moving. However, when the water drops below 50 cm/sec, Particle A falls below its fall velocity and is deposited. Based on this information, what is the likely particle size for this object? (Q47)

10 mm

In the hydrologic cycle, water that falls on land in the form of precipitation returns to the ocean in which of the following pathways?

-All of the responses are correct. -streams -further precipitation -groundwater flow -runoff

As stream velocity slows, the smallest particles get deposited first.

False

Look at the two graphs below. Label each graph with the scenario it most likely represents. Notice that for each graph, a similar rainstorm occurs, releasing a certain amount of water into the environment. The horizontal (x) axis represents time. The light blue curve shows the amount of streamflow (called river discharge) in each environment. Drag the appropriate items to their respective bins (Q70)

Graph 1: Flooding in an urban. This setting is more likely to produce flash floods. Concrete surfaces mean water flows directly to the stream or river after a storm. Graph 2: Abundant open farmland allows for infiltration of water into the ground. Flooding in a rural area.

What is a floodplain?

a flat surface next to a river channel

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

corrosion

Water erodes the outside of a river bend to form a __________.

cut bank

What is the geologic definition of a stream?

A channelized body of water flowing down gradient

Where are bedrock channels more likely to be found?

Bedrock channels are typically found in the headwaters of river systems where streams have steep slopes.

Match the type of sediment load to the correct definition (Q35)

Dissolved Load−ions in solution that are dispersed throughout the flow. Bed Load−larger sediments that bounce, roll, or slide along the bottom Suspended Load−fine sediments that are held up by the water and carried throughout the water column.

Determine the zone where each of the depicted features occurs. Drag the appropriate items into their respective bins. Each item may be used only once. (Q71 part C)

Erosion: Waterfall Transportation: cut banks and point bars Deposition: Alluvial Fan Delta

The amount of meandering that occurs in a stream influences the gradient in which of the following ways?

With more meanders, the stream gradient decreases.

What factors would decrease flow velocity?

-a decrease in stream discharge -having a rough channel -a decrease in gradient of the stream

Rank the following sources of water from largest to smallest in terms of percentage of the world's total supply.

-oceans -glaciers -groundwater -non-glacial ice and snow

The diagrams below show the evolution of a stream valley into a floodplain. Stream valleys are narrow, V-shaped terrains formed by stream erosion. In contrast, floodplains are broad, flat plains formed by stream deposition. Whether a stream valley or floodplain forms in a particular region depends on the stream's proximity to base level. Arrange the diagrams based on the proximity of the stream to its base level. Arrange them from highest above stream base level (left) to nearest stream base level (right).

Highest to Lowest Narrow V-shaped Valley Site of erosion/ site of deposition Site deposition/ well developed floodplain

What is discharge a measurement of?

the amount of water flowing in a river

What is suspended load?

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

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

Floodplains

The figure above shows that the water in a meandering stream is uniformly distributed. There are no holes or tears in the stream, and there are also no regions of stretched or compressed water. Therefore, the water can't be flowing with uniform acceleration. As water flows around a bend, some parts must accelerate more than other parts, and this results in zones of erosion and deposition along the meandering stream. In the exercise below, identify the zones of erosion and deposition on the main image, and also the location on the inset image - flow diagram where there is minimum and maximum acceleration. Drag the appropriate labels to their respective targets. (Q71 part B)

Left to right Top Red : Maximum Acceleration and Maximum Acceleration Bottom Blue: erosion and deposition

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

clay

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

braided stream

Which of the following rivers is the largest river in North America?

the Mississippi River

Transpiration moves water from _______

the biosphere to the atmosphere

Why doesn't sea level drop even though oceans have a higher rate of evaporation than precipitation?

Surface water running off into the oceans makes up the difference between evaporation from the oceans and precipitation into the oceans, creating a balance.

How does an alluvial fan form?

When a stream with a steep gradient emerges onto a relatively flat lowland, its gradient drops, and it deposits a large portion of its sediment load in a pattern that looks like a fan from above.

What is a flood?

When discharge in a river exceeds the river's capacity

Which of the following are part of the bed load?

gravel sand

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

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 statements about the global water supply is true?

Decreased precipitation could impact water supply available for humans

Match the landform with the correct description.

Delta- form where streams enter large lakes or oceans Levee- formed by floodwaters o either side of a stream Alluvial Fan- formed by mountain streams emerging onto a flat plain Bar- small deposits that form in the stream channel.

At approximately what velocity will a 0.1 mm sediment particle begin moving in the stream? (Q46)

0.6 cm/sec

Each of these strategies has particular strengths and weaknesses. Fill in the following sentences with the correct type of flood control. Match the types of flood control to the appropriate blanks in the sentences below. Make certain each sentence is complete before submitting your answer.

1.Besides flood control, a(n) dam can also be used to generate hydroelectric power. However, they are expensive to build and maintain. 2. Removing obstructions from a river channel is a form of a(n) channelization. It can make a river more navigable, but may also increase bank erosion due to increased water flow. 3. A(n) artificial levee confines water flow and can experience significant erosion. Constant maintenance is required. 4. Zoning regulation is/ are cheap to implement, but it/they can adversely affect property values.

X marks the site of oil drums that were illegally buried by the Shay-Dee Oil Corporation. These oil drums have begun leaking and the leaking oil has flowed downslope to the stream below, contaminating the stream. Which stream drainage basins would be affected by this oil?

C and A

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 infiltration?

Water soaking into the ground

Water in the hydrologic cycle readily moves from the land to the oceans through several pathways. How does the vast majority of water get from the ocean to the land surface?

clouds and precipitation

What type of stream is associated with the formation of an oxbow lake? (Q49 part A)

meandering stream

What type of drainage pattern develops on highly jointed bedrock?

rectangular

Match the appropriate terms to their correct locations next to the stream in the image (Q26)

A. Headwaters B. Meandering Channel C.Delta

Stream channels have three major zones, from their headwaters to the mouth, and each zone exhibits unique characteristics. Label the zones of a river system based on the dominant process operating within each zone. (Q31 part A)

Going down slope of model -Zone of sediment production -Zone of sediment transportation -Zone of sediment depsosition

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

Hydrologic Cycle

What is the name for the stream feature in this image?

Incised meander

Using the information provided above, describe what changes will happen to the stream and its streamflow as the water moves from the head to the mouth. (Q27)

The channel roughness and slope decrease while the discharge, channel size, and flow velocity increase

Match the words in the left column to the appropriate blanks in the sentences on the right. (Q32)

The geographical area where all surface water converges to one location is called its drainage basin A delta forms at the mouth of a river, where the velocity of the water flow decreases and deposition is highest. The volume of water flowing past a certain point in a given amount of time is a river's discharge The headwaters of a river have a steep gradient, high channel roughness, and low water volume A stream with a low to moderate gradient, carrying most of its load in suspension, should be characterized by many curves and bends called meanders. A river with a well-developed floodplain has a flat low-lying channel and experiences flooding during periods of high discharge.

What is the mouth of a stream?

The location where one stream flows into another body of water

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

The stream will lose water to the groundwater system

What kind of streamflow is present in this image? (Q24)

Turbulent flow

How will the flow in this image affect erosion of the stream channel? (Q25)

Turbulent flow contributes to erosion because it lifts particles from the streambed

What percentage of Earth's water is in the form of seawater?

97.2%

Where are the headwaters of the Mississippi River?

Northern Minnesota

Analyze the graph and sort the following characteristics as those which appear at the headwaters and mouth of the stream. (Q31 part B)

At Headwaters: Channel size is smaller Channel roughness is high At mouth: Flow velocity is more Slop is lower discharge is higher

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

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

The ________ is an elevational point that divides an entire continent into large drainage basins.

Continental divide

Which of the following statements about deposition and erosion around meander loops is true? (Q56 part C)

Erosion occurs where water is moving the fastest along the outside of the loop. Deposition occurs where water is moving the slowest along the inside of the loop.

What has caused the hypoxic "dead zone" to form off the coast of the Gulf states?

Fertilizers promote the growth of algae. When they die and decompose, oxygen is depleted in the Gulf of Mexico.

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

Floods

Below is a photo from the meandering channels at Missouri Headwaters State Park, in southwest Montana. At this location, the Missouri River is formed at the confluence of the Gallatin, Madison, and Jefferson Rivers. This river flows 2,341 miles before joining the Mississippi River, and is considered the longest river in the United States.Different processes influence the lateral migration of a meandering channel in its valley. Erosion, transport, and deposition all play significant roles in shaping a river through time. Focus on the locations in the channel where velocity is fast and slow, where along the channel erosion and deposition is occurring, and which direction the channel will migrate through time. Drag the appropriate labels to their respective targets. Not all labels will be used (Q55 part B)

Left to Right Blue: Erosion Red: Faster water velocity Red: Slower water velocity Blue: Deposition Arrow <------

A flood plain is the flat area around the river extending from its channel to the edge of the wide valley. (Q55 part A)

Left to right Point Bar Scroll Bars Cut Bank Floodplain

Identify the stream drainage pattern with the correct name: Radial, Rectangular, Trellis, or Dendritic. (Q66 part A)

Left to right Top: Rectangular, Trellis Bottom: Dendritic, Radial

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

Lined with silt

What kind of stream channel is visible here? (Q52)

Meandering channel

Based on the characteristics of the sediments, such as size, mass, and solubility, the sediments are classified into dissolved, suspended, and bed loads. Dissolved loads comprise sediments that are very small in size and are carried in solution. Suspended loads are sediments that float in the water since they are neither large/massive enough to settle down on the stream bed nor are soluble enough to dissolve completely. Bed loads are all the coarser sediment that are bigger and heavier in size and shape. The ability of a stream to erode and transport sediments is directly related to its velocity, which is the speed at which water flows through a stream. You will match the influence of velocity associated with each type of load transport. (Q31 part C)

Nature load: Dissolved load- unaffected by velocity of stream Suspended load- affected by both flow velocity and setting velocity of stream Bed load- Highly affected by the velocity of stream

How are oxbow lakes formed? (Q49 part E)

Oxbow lakes form when one meander erodes into another, cutting off water to part of the stream channel

What is an oxbow lake? (Q49 part D)

a meander that has been cut off from the original stream channel

What is a natural levee?

a ridge of flood deposits next to a river channel

What is a graded stream?

a stream that neither erodes material nor deposits it but merely transports it

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

Which of the following choices does not directly affect stream velocity?

location of the drainage divide

While working on a stream in your field study area, you find that the channel width is 20 meters, the channel depth is 2 meters, and the velocity is 1.2 meters/second. What is the discharge of this stream?

48 m3/s