CHAPTER 16

Summarize the formation of a natural bridge by matching the locations with the process most likely to occur there as the river continues to erode the surrounding rocks.

1 - Natural bridge 2 - Abandoned meander

Rank the following events in order to explain the formation of a natural arch, placing the beginning event on top and the final event on bottom.

1. Layers of strong rock are present. 2. Parallel, vertical joints develop in rock layers; weathering attacks the surface area exposed by the jointing. 3. Notches form where joints are located; notches capture and channelize water to increase erosion. 4. Landscape becomes narrow fins of rock, flanked by lower, more eroded areas and isolated knobs. 5. Part of a fin falls due to gravity, and an opening forms in the rocks. 6. The opening grows larger and becomes more arch-shaped

Rank the seasons from the lowest discharge of water to the highest for a river located in the Upper Midwest of the U.S. (Place the season with the lowest discharge on top.)

1. Winter 2. Fall 3. Summer 4. Spring

What is the discharge for a river that is 5 meters deep, 15 meters wide, and has a stream velocity of 2 meters per second?

150 m^3/sec

The 1993 flood of the Mississippi River at St. Louis began June 26 when the river reached the flood stage, and peaked August 1st. The flood peak was about ___________ feet above flood stage.

20

Use the following information to calculate the gradient of River X. If the vertical change is 20 meters in 1 kilometer, then the gradient expressed in m/km is ______.

20

On a field trip, you measure the following: river depth = 7 feet; river width = 12 feet; and river velocity = 3 feet/sec. What is the discharge?

252

The gradient of this stream is ____________ m/km.

7

What is a floodplain?

A broad strip of land built up by sedimentation on either side of a stream channel and covered with water during a flood

Match the phrases to describe how a stream profile is influenced by changes in its environment.

A drop in base level - will result in more downcutting An increase in rainfall - will increase discharge and sediment load capacity Subsidence in the mountains - will flatten gradient, causing deposition

If you examined a hydrograph and saw peak discharge in a small amount of time, then a quick decline in discharge, what might have been a possible explanation for the peak?

A heavy rainstorm event upstream

What is a bedrock stream?

A mountainous stream flowing through a carved bedrock channel

What is a drainage divide?

A ridge or strip of high ground separating one drainage basin from another

What is a point bar?

A sandbar deposited along the inside of a stream meander due to lower velocity

Where do deltas form?

At the mouth of a river that empties into an ocean or lake

Which of the following physical parameters show a decrease from the headwaters to the mouth of a river?

Maximum grain size

Select the two conditions that resulted in the 1993 upper Mississippi River flood.

Severe precipitation was caused by warm moist air from the Gulf of Mexico and cold Arctic air merging. The ground was already saturated from early spring rains.

What process generally defines a nickpoint and forms waterfalls?

The channel bed below the nickpoint has a faster erosional pattern than above the nickpoint.

True or false: Increasing the rate of runoff increases the likelihood of flooding in local streams.

True

A stream ______ erode below its base level.

cannot

The volume of water flowing through any part of a river per unit of time (discharge) is calculated by ______.

multiplying the velocity by the cross-sectional area of the river

The size of the drainage basin and the ______ the drainage basin influence the flow response to rainfall.

shape of

The Upper Mississippi River ______.

was created by glacial meltwaters is young

An important and widespread geologic agent in eroding, transporting, and depositing sediment is flowing ____________.

water

Changes in the ______ can begin or end the life of a river.

water or sediment supply at the source slope the river flows across elevation at the base level

Deposition in bedrock channels occurs along riverbanks and behind obstacles as ______.

water velocity decreases

A nickpoint is a location where a stream has an abrupt change in gradient and can form a(n) ___________.

waterfall

A stream deposits the sediment it is carrying ______.

when it no longer has the capacity to do so Reason: That could be caused by a decrease in discharge.

When comparing their ages, the Upper Mississippi is __________ than the Lower Mississippi.

younger

Rank in order from the beginning (at the top) the processes necessary to create entrenched meanders.

1. A meandering river flows across floodplain. 2. A tectonic event causes an uplift, causing the river to erode downward. 3. Further incision by the river creates more entrenchment.

Rank the following in order to describe the formation of a natural bridge, placing the beginning event on top and the final event on bottom.

1. A meandering stream carves a curved canyon from a landscape. 2. Entrenched meanders are formed as the stream erodes into deeper layers of rock. 3. The river erodes laterally to make rock between entrenched meanders thinner. 4. The river cuts through ridges between meanders and alters its original path. 5. A natural bridge is formed along with an abandoned meander.

Rank the following particle sizes transported by water from smallest to largest. (Place the smallest particle size at the top.)

1. Clay 2. Silt 3. Sand 4. Cobbles 5. Boulders

Rank the formation of terraces by rivers from the first stage at the top to the last stage on the bottom.

1. Deposition of sediment occurs on the floodplain 2. A drop in the base level of the river results in downcutting through deposits. 3. Further downcutting occurs, and the river abandons the previously formed floodplain. 4. The oldest floodplain becomes isolated as the river downcuts, leaving a terrace.

Order the sequence of layers produced as a delta builds out into the oceans from flowing rivers, as you would see them in a cross section.

1. Horizontal beds deposited partly on land 2. Cross-bedded sediments 3. Marine clays

What is a stream terrace?

A stream terrace is an old floodplain perched outside and above the current floodplain.

What is a braided stream?

A stream that flows in a network of many interconnected rivulets around numerous bars

These are formed when a steep drainage enters a broad valley and the sediments and debris are deposited.

Alluvial fans

What is a natural bridge?

An arch-shaped features that span a (former) stream

Compare antecedent and superposed streams by matching them to their correct descriptions.

Antecedent - A stream incises as geologic structures in and around it change and form while the stream stays in the same place. Supreposed - A river incises into soft sediment, and becomes trapped in its own canyon as it encounters geologic structures.

The Fall Line is located between the ______ Mountains and the coast, and is marked by ______.

Appalachian; waterfalls

Over the last 7,000 years, the mouth of the Mississippi River has moved. What evidence supports the different end points of the river?

As least six huge abandoned sediment deposits mark where the river created a delta.

Which of the following is the correct relationship between river velocity and sediment load?

As velocity increases, so does the river's capacity to carry a larger load.

Where is the peak discharge on this hydrograph?

B

Which curve (A or B) on the hydrograph represents a steeply sloped basin with respect to runoff of water after a storm?

B

The image shows a stream hydrograph of a flood where discharge is on the vertical axis, time is on the horizontal axis, and the red line is the flood stage. Which labeled point shows where the flood begins?

B, where the stream rises to the flood stage

The area that a stream naturally drains is called a drainage __________.

Basin

Which of the following locations would be the two most common areas in which to find a braided stream or river?

Broad, sloping plains that flank mountain ranges Flat-bottomed valleys between mountains

In mountain streams that are steep with high stream velocities, which pattern of erosion is the most common?

Channel bed is eroded faster than the channel sides.

Which of the following physical parameters show an increase from the headwaters to the mouth of a river?

Channel size Discharge Sediment load

______ are formed as flowing water collects in natural cracks or low spots. Once formed, these capture additional runoff within the drainage basin.

Channels

Select the answer that is not a factor in the deposition of deltas.

Chemical makeup of sediment

Select conditions that have an effect on the flow of river systems over time.

Climate Dams Runoff Tectonism Geology

Steep slopes in a(n) narrow canyon plus an unusually large thunderstorm resulted in the 1976 Big Thompson River flood near Estes Park, _____________.

Colorado

Which large river runs from the high Rocky Mountains to western Mexico passing lakes, dams, reservoirs, geologic structures, incised meanders, and finally a delta on its journey? The ___________ River.

Colorado

Which of the following is not a characteristic of a braided river or stream?

Constant flow

Why do the meanders on a stream migrate?

Continuing erosion and deposition

Match the condition on the left with the effect on the river or drainage system on the right.

Dam - Changes the base level because of sediment buildup Tectonism - Can increase the slope and supply of coarse sediments Runoff - Increases flow, causing flooding Geology - Streams erode soft rocks more easily than hard rocks Vegetation - Plants stabilize stream bank and protect against erosion

Select the human-caused flooding events from the list of flood causes below.

Dam failure Urbanization

Match the type of sediment load to its description.

Dissolved - Chemically soluble ions transported by the river Suspended - Clay and silt carried indefinitely above the riverbed Bed - Material carried on the bottom of a river by pushing, bouncing, rolling, and sliding; usually sand and gravel

What happens to the erosive power of a river as velocity increases?

Erosion increases.

Select all the natural causes for flooding from the list below.

Eruption of snow-covered volcano Snowmelt Regional precipitation Local heavy precipitation

Which of the following are considered to be causes for severe flooding events other than precipitation alone?

Failure of a dam Prolonged drought followed by intense precipitation Stalled hurricane Rainfall coinciding with snowmelt and ice dams in a river

The red line marks the __________ Line, the boundary between hard bedrock in the mountains and soft sediments in the coastal plains. Stream gradient changes here, and it is marked by a series of _________.

Fall, waterfalls

True or false: The position of the Mississippi River delta has been remarkably stationary for the past 7,000 years.

False

Match the factor or process with how it influences or changes a stream profile.

Flow over unconsolidated sediments - Stream profiles are smooth, as these are easily eroded. Tectonic uplift - This causes stream to incise into the landscape. Rise in sea level - This causes the stream to deposit sediment along the coastline.

In which location would a geologist look for a river confined to a single channel?

Gentle Plains

Which drainage basin covers the largest area in the United States?

Gulf of Mexico

What problems are associated with straightened or channelized stream channels?

Increased erosion downstream Downstream flooding Reduced sediment deposition downstream

What is happening to coarse-grained sand in a stream velocity of 70 cm/s?

It is being transported as bedload.

What is happening to silt and clay in a stream velocity of 5 cm/s?

It is being transported as suspended load.

Which of the following describe the largest known flood along the Colorado River?

Its discharge is estimated using geomorphology. It occurred before humans were in the area. It had a discharge of approximately 8,500 m3/sec.

Select from the list below the two large reservoirs created by damming the Colorado River.

Lake Mead Lake Powell

Match the location of the diagram with a description of the shape of the river.

Left-side diagram - Braided river Middle diagram - River with low sinuosity Right-side diagram- Meandering river

What types of streams typically deposit clay- to sand-sized sediments?

Low-relief streams

How can the melting of an ice sheet or glacier affect a river's drainage?

Melting of the ice releases tremendous amounts of water and sediment that lead to new or larger channels. Uplift of the land after the glacier melts can change drainage patterns and direction.

The Colorado River starts in the Rocky Mountains in the United States and has its mouth in _____________.

Mexico

During the 1993 flood on the upper __________ River, floodwaters flowed onto the floodplain because levees did not hold the water back. It took months for the floodplains to dry out because the _____________ trapped the water, preventing it from flowing back into the river channel.

Mississippi; levees

Match the feature with its description.

Natural arch - A large opening that goes all the way through a narrow panel of rock Fin - A narrow panel of rocks that is the result of weathering controlled by joints on both sides Window - A small opening that goes all the way through a narrow panel of rock

On the diagram shown, look at the channel profile at the place labeled "cutbank." Where is the deepest water? The shallowest water?

On the outside of the bend; on the inside of the bend

What is an incised stream?

One that has eroded into the underlying rock

How long was the Mississippi River above flood stage in St. Louis during the summer of 1993?

Over 3 months

Which two drainage divides are separated by the Continental Divide?

Pacific Ocean Gulf of Mexico

From the list below, select the factors that control the deposition of a delta.

River and ocean ice Wave action Discharge Vegetation Sediment load

Select the three measurements needed to calculate discharge of a river at a certain point.

River depth Velocity of the water River width

What types of sediments or rocks are deposited by low-relief streams?

Sand Clay Silt

Which of the following are primary factors that influence a stream's profile?

Sea level Tectonics Rock type Climate

What occurred to decrease the gradient of the Lower Mississippi River, causing it to deposit sediment within the valley it has previously incised?

Sea level rose.

Select common features located along low-gradient rivers.

Single channels Floodplains River terraces Meanders

What three factors of a drainage basin influence the flow response to rainfall?

Slope Shape Size

What are distributaries?

Small, branching channels that carry water away from the main channel

Select two ways that mountain streams obtain their sediments.

Soil and/or sediment slides down into the drainage area. Tributaries bring sediments into the drainage area.

Which of these would indicate a flood on a stream hydrograph?

Stream discharge that is greater than the flood stage for the channel

Which of these has a concave-up shape?

Stream elevation profile

Match the river drainage pattern with the appropriate description of its geology.

Structurally controlled pattern - Drainage occurs on eroded layers or structures and then cuts across a ridge to follow a different weak layer. Radial drainage pattern - Drainage is found on symmetrical mountains such as volcanoes. Dendritic drainage pattern - Treelike pattern develops on rocks with similar resistance to erosion.

The formation of a natural arch requires which of the following?

The formation of fins Erosion by water and/or wind A strong type of rock

What is a drainage basin?

The naturally defined area that a stream drains

A community experiences two floods with stream discharge equal to the 100-year recurrence interval. The floods occur in 1980 and 1990. When will or did the next flood occur?

The next 100-year flood could occur in any year. Reason: One hundred-year floods statistically occur once every 100 years but can and do occur in clusters.

What is stream abrasion?

The process of grains chipping, scraping, and sandblasting the streambed as they move downstream

Which of the following are ways in which tectonism, such as an uplift of a mountain, can affect drainage?

The uplift can increase the slope of the drainage. The uplift can increase the supply of coarse sediment. The uplift can increase precipitation into the drainage. The uplift can cause a rain shadow on the other side, causing a decrease in the runoff into the drainage.

What characteristics do rivers and streams share?

They can be braided or meandering. They flow downhill due to gravity. They flow within a channel.

Select the conditions that caused the 1976 Big Thompson River flood near Estes Park, Colorado.

Unusually severe thunderstorm Narrow canyon Steep slopes of the river canyon

From the list below, select the characteristics of a braided river or stream.

Variable flow Steep gradient Abundant sediments

Which two of these do you multiply to determine the discharge of a river?

Velocity of the river Area of the river

What is a flood?

Water overflows a stream's channel.

Select consequences to a river when a dam is constructed.

Water released from the dam is clear (no sediment) and has a new capacity to erode and transport sediments downstream. The dam creates a temporary base level for the river. The dam causes the river to deposit its sediment load upstream of the dam.

Define the landforms associated with the headwaters of mountain streams.

Waterfall - Occurs when a stream or river's gradient is so steep that water goes over the ledge or cliff. Rapid - Occurs along a river and is characterized by turbulent water Lake - Occurs where water is impounded by some obstruction

When are stream eddies formed?

When turbulence increases

Do changes in tectonics, human development, and geology affect river systems?

Yes

A decrease in the size of sediments carried by a river usually reflects ______ in the gradient of the river.

a decrease

When conditions such as climate remain stable, a river may approach a dynamic equilibrium state. The river would then be considered ______.

a graded stream

When steep, narrow drainages enter broader, more gentle valleys and streams deposit the large sediments they are carrying and form ___________ ____________.

alluvial fans

Geologists use large water tanks in laboratories to study braided river dynamics. They control the slope, the ______, and the consistency of water flow to study how the variables affect the stream system.

amount and type of sediment

The erosional base level of a river can be ______.

an ocean a lake a closed land basin

Streams that are associated with and predate the formation of a geologic structure are ______, whereas a stream that is established in association with but after the formation of a geologic structure is ______.

antecedent; superposed

The headwaters of the Colorado River ______, and the mouth is at the Gulf of California.

are in the Rocky Mountains

Multiplying the width of a channel by its average depth will give you the _____________ of the channel.

area

Oceans, lakes, or the bottoms of closed basins are all examples of ________ levels of rivers.

base

The lowest level to which a river can erode is its ______.

base level

A stream in a mountainous area that is carved from bedrock is called a(n) __________ stream.

bedrock

The process of meander formation begins when a difference in roughness on the ______ causes water to move faster on one side of the channel than on the other.

bottom

A stream that flows in a network of many interconnected rivulets around numerous bars is a(n) __________ stream.

braided

The type of rivers that are characterized by a network of interweaving sinuous channels, with the overall channel being fairly straight, are ____________ rivers.

braided

One stream may divert the flow of another stream into a different basin through the process of stream __________. This occurs during ___________ erosion.

capture; headward

Rivers on gentle plains usually occupy a single ______ rather than being braided.

channel

As water flows, it accumulates in natural cracks, which eventually form ______ rather than spreading across the land.

channels

When a river enters an ocean and begins depositing sediments to form deltas, the first particles to settle out are large particles and sand followed by _____________ and __________, which settle farther offshore.

clay; silt

Besides sea level and rock type, the other two primary factors that influence a stream or river's profile are _________ and ___________.

climate OR tectonics

Most streams have ______ profiles.

concave-up

In a meandering river, the deeper outside bend is eroded into a steep riverbank referred to as a(n) _____________, and on the shallower opposite side of this is a(n) ___________ bar.

cutbank; point

Features that occur along the Colorado River include ______.

dams geologic structures natural lakes lava flows

As the gradient decreases in a river, the size of the sediment that can be transported ___________.

decreases

The feature formed when a river deposits its sediment near its mouth is a(n) ______.

delta

The feature that is formed where a river meets the sea, slows down, and deposits its sediments is a(n) ___________.

delta

When rivers enters a lake or an ocean, they slow down and lose their capacity to carry sediments, forming ______.

deltas

______ are formed as rivers slow down when they reach their mouth and empty into an ocean.

deltas

The drainage pattern associated with areas where the rocks have the same resistance to erosion is a ________ pattern, whereas __________ drainage patterns are found on symmetrical mountains.

dendritic; radial

The drainage pattern associated with areas where the rocks have the same resistance to erosion is a ________ pattern, whereas _____________drainage patterns are found on symmetrical mountains.

dendritic; radial

Bedrock channels occur where erosion by a stream has cut down into the local bedrock. Although erosion is the dominant process, ______ tends to occur where and when flow velocity decreases. Lower velocities can often be found behind objects, such as boulders, in the stream.

deposition

When the amount of sediment exceeds the ability of the current to carry it, the stream _____________ the sediment.

deposits

Potholes or bowl-shaped pits are formed when flowing water and sediments swirl in small __________ in the rock.

depressions, holes, pits OR cavities

The amount of water flowing through a channel over a given amount of time is called its ______.

discharge

The volume of water flowing through a stretch of a river is the __________ and is measured by multiplying the river depth by river width and river velocity.

discharge

Soluble materials in flowing water are removed and transported by a process called ______.

dissolution

What is the name for small, branching channels that carry water away from the main river channel and distribute it over the surface of the delta?

distributaries

A ridge or strip of high ground that separates one drainage basin from another is referred to as a drainage __________.

divide

As the velocity of water increases so does the turbulence. This results in the formation of swirls in the current called ___________.

eddies

The gradient of a stream or river is defined as the change in for a given horizontal distance.

elevation OR height

As meanders develop on a floodplain and either the base level drops or a tectonic event causes uplift, the meanders deepen and become _________.

entrenched

Acting as major sculptors of Earth's surface, rivers and streams __________ the landscape, carry the materials, and later deposit the sediments.

erode

On the outside of a meander, the water velocity is faster and causes ______, and on the inside of a meander, the water velocity is slower, which causes ______.

erosion; deposition

Meanders cause differences in water velocity in the river channel. On the outside of a meander, water velocity is ______ and causes erosion, while on the inside of a meander, water velocity is ______ and deposition of sediments occurs.

faster; slower

A stream with no tributaries is a ______-order stream.

first

A flood that is characterized by high discharge over a short time frame is called a(n) ____________ flood.

flash

An event in which the amount of water flowing through a river channel overflows its banks is a(n) __________.

flood

Human-constructed barriers such as levees are beneficial because they can help prevent _____________; however, it is difficult to construct an affordable levee that will not fail during the worst situations.

flooding

A broad strip of land on either side of a stream channel that is covered by water during a flood and replenished by sedimentation is a(n) ____________.

floodplain

Large water tanks in laboratories are used by geologists to study water ______ in river systems because the tanks can be used to control the slope of the river and the type of sediments.

flow

Viscosity is the resistance to __________ exhibited by fluids.

flow

What is a very common and important geologic agent in eroding, transporting, and depositing large amounts of sediment daily?

flowing water

The discharge represented by B on this hydrograph is for a basin with ______ slopes.

gentle

When a river is in a steady state in which the balance between the supply of sediment and the amount of sediment that the river can carry is in a near equilibrium, the river is referred to as a(n) _____________ river.

graded

What is the word used to describe the change in elevation for a given stream or river over a horizontal distance?

gradient

Rivers are dynamic systems driven by precipitation and _________. (Hint: the answer is just one word.)

gravity

The driving force behind a river's flow is ______.

gravity

The force behind a river's flow from high to low elevations is _________.

gravity

In flowing water, the upstream side of an obstruction is subjected to the ______ of abrasion.

greatest amount

Streams can expand the area of the basin by ______ which may lead to ______.

headward erosion; stream capture

The profile of a river is steeper at its ______.

headwaters

The origin of a river is called its ____________, and the end of a river is called its _________.

headwaters; mouth

The area of the origin of a river is its ______, and the ______ the end of the river.

headwaters; mouth is

The more years of river flow data that are collected, the ______ the probability of predicting a major flooding event.

higher

The ______ the velocity of a river, the ______ its capacity to carry sediment.

higher; larger

Channel beds erode faster than the channel sides in ______ streams and rivers. These are generally steep mountain streams.

highly turbulent high-gradient high-velocity

The probability that a discharge of a certain size will occur during any given year is calculated using ______.

historic raw data

Many historic floods are associated with the large precipitation that accompanies a(n) _____________; a good example is the storm named Mitch in 1998 that brought 78 inches of rain in some places in a few days.

hurricanes OR typhoons

The type of graph used to display the change in a river's discharge over time is a(n) ___________.

hydrograph

Streams that have cut down into bedrock and flow through bedrock channels are called ______ streams.

incised

As water velocity in a stream increases, turbulence increases, resulting in a(n) ______ in the water's ability to erode and transport sediment within a channel.

increase

The uplift of high mountain ranges increases slope and precipitation causing a subsequent _____________ in the amount of sediment available for a stream to transport.

increase

The uplift of high mountain ranges increases slope and precipitation causing a subsequent ______________ in the amount of sediment available for a stream to transport.

increase

The estimates for a 100-year flood on the Colorado River near Lee's Ferry are based on ______.

inferred discharge of historic floods

When a river floods and deposits sediment parallel to and along the river channel, a(n) __________ is formed.

levee

Flooding can be prevented by building ____________ parallel to river channels. However, these structures do fail, and construction to prevent the worst possible flooding events is not affordable.

levees

Meanders, floodplains, and river terraces are commonly found along __________-gradient rivers.

low

The part of the Mississippi River that carved itself a river valley over Cenozoic sedimentary rocks when sea level was low, and then filled the valley with deposits when sea level rose, is the __________ Mississippi.

lower

The production of ice sheets during global cooling results in __________ sea levels. These ice sheets can depress the _____________, causing river drainages to flow toward the ice sheets.

lower; crust

The base level of a river is the ___________ elevation to which the river can erode.

lowest

Braided rivers carry more volume and larger size ranges of sediment types than _____________ rivers.

meandering

Flat-bottomed valleys between mountains would be good places to look for ______ rivers or streams.

meandering

Because of continued erosion and deposition that leave behind scars and point bars, river ______________ migrate back and forth across a flat valley floor.

meanders

The discharge of a river is measured in cubic ____________ per second.

meters OR feet

The size of sediments in braided rivers typically is ______ than that carried by meandering rivers.

more varied

The cross-sectional area of the channel of a stream or river is calculated by ______.

multiplying the channel's width by its average depth

A large opening that goes all the way through a narrow panel of rock is called a ______. A smaller, but similar opening is called a ______. These features may form in areas where a narrow panel of rocks, called a ______, has formed due to weathering controlled by joints on both sides.

natural arch; window; fin

______ are formed beside low-gradient rivers when floods occur and sediments build up along the channels. These features become barriers to water returning to the river from the floodplain.

natural levees

A flash flood ______.

often results from intense rainfall lasts a short time

A cutoff meander may develop into a(n) ________ lake.

oxbow

When meander scars are filled with water, they are ______.

oxbow lakes

A stream or river that flows all year is ______.

perennial

A stream that flows year-round is a(n) stream, whereas a(n) stream does not flow the entire year.

perennial; ephemeral OR intermittent

A depositional feature that has been built on the inside of a stream channel curve because of lower velocity is a ______.

point bar

The bowl-shaped pits that are created when flowing water and sediments swirl in small depressions are ________.

potholes

Streams are systems driven by ______.

precipitation AND gravity

The ability to determine the ______ of a flooding event is based on river flow data. The more data collected and the greater the time span for data collection, the better understanding we have of the chance of future flooding events.

probability

When water flows chaotically through narrow channels or over large rocks and other debris that partially block the channel, ____________ are formed.

rapids

When water flows chaotically through narrow channels or over large rocks and other debris that partially block the channel, _____________ are formed.

rapids

The principal processes that sculpt Earth's landscape are erosion and deposition by _________.

rivers OR streams

The movement of sand grains by a series of short leaps or bounces along a streambed is _________.

saltation

The type of sediment transport that involves a series of leaps or bounces off the bottom of a streambed is ___________.

saltation

Meandering rivers leave behind exposed curved ridges called meander ____________marked by lines of vegetation or as curved dry depressions. When the depressions are filled with water, they are ____________ lakes.

scars; oxbow

A river cannot erode below ______.

sea level

A tributary that itself has a tributary within a drainage system is a(n) ____________-order stream.

second

A delta is formed where a river meets an ocean because ___________ is deposited as the river loses speed.

sediment

Construction of dams causes an interruption of river flow. River _________ are deposited upstream of the dam, shortening the life of the reservoir.

sediment

The ______ load is the total amount of sediment carried by a river.

sediment

The higher the velocity of a flowing stream, the larger its capacity to carry ________.

sediment

Slope failures from the surrounding mountain slopes and tributaries are the two sources of ______ in mountain streams.

sediments

The particle size transported by water that is in between clay and sand is ____________.

silt

The amount that a river or stream channel curves in a given length is called its ______________.

sinuosity

The gradient of a stream or river is defined as the change in ___________ for a given horizontal distance.

slope OR profile

The gradient, or __________ of a stream is steeper near the headwaters than at the mouth.

slope OR profile

Dissolution is the process by which _____________ materials are removed and transported by flowing water.

soluble

Dissolution is the process by which _________ materials are removed and transported by flowing water.

soluble, dissolved, OR water-soluble

With respect to the seasons, the highest discharge of a river in the Upper Midwest is usually in the ____________ and the lowest discharge is during the _____________.

spring; winter

We disrupt the balance of a river system when we discourage the process of migration and meandering by ______ streams.

straightening

Changes in water or sediment supply, change in slope, or changes to base level elevation can begin or end the life of a(n) ___________.

stream

Rivers and streams are similar bodies of flowing water. A(n) ____________ is a body of water with a current that flows downstream within a channel. A(n) ___________ is a large body of water with considerable volume and permanent or seasonal flow.

stream; river

A river ___________ is formed as a river incises into the surrounding rocks and sediments, abandoning the floodplain and leaving a record of the river's historical size and location.

terrace

Older floodplains that are perched above current floodplains are called stream ___________.

terrace

River ______ are relatively flat benches that are perched above a river or stream and stair-step upward and outward from the active channel.

terraces

The flat benches that are perched above a river or stream and that stair-step upward and outward from the active channel are __________.

terraces

The flat benches that are perched above a river or stream and that stair-step upward and outward from the active channel are ___________.

terraces

The formation of the Salton Sea occurred in 1905 during a flood of the Colorado River. It occurred in an area ______.

that historically had a lake

The Salton Sea in California was formed in 1905 when ______.

the Colorado River flooded

Sinuosity refers to ______.

the amount that a river or stream channel curves in a given length

A hydrograph shows ______.

the change in a river's discharge over time

Waterfalls, lakes, and large boulders are landforms that characterize ______.

the headwaters of mountain streams

The term "100-year flood" signifies ______.

the size of a flood that is predicted to have a 1 in 100 probability of occurring in a given year

Smaller subsidiary channels that feed the main channels of rivers are ______.

tributaries

What is the name of the subsidiary channels that join up with the main river channel?

tributaries

When the gradient of a stream steepens or the channel is constricted by bedrock or obstacles, the flow of water becomes ______ forming ______.

turbulent; rapids

The graphs geologists use to estimate river flow probability are ______.

unique to each stream

The turbulence of water increases as the water's ______ increases, which can increase the water's ability to erode and transport materials within the channel.

velocity

The property of a fluid that is defined as the resistance to flow is _________.

viscosity