GY 102 Assignment 7

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

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

The type of feature that forms when a steep, narrow drainage enters a broader, more gentle valley and a stream deposits the large sediments it is carrying is a(n) _______ ________

1. alluvial 2. fan

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

1. climate OR weather 2. tectonics

_________ drainage patterns are associated with areas where the rocks have the same resistance to erosion, whereas ________ drainage patterns are found on symmetrical mountains.

1. dendritic 2. radial

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

1. perennial 2. ephemeral OR intermittent

Rafters enjoying a mountain river trip encounter both turbulent _______ and calm ________ located upstream of the turbulent areas.

1. rapids 2. pools

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.

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 weaker 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.

Streams that carve directly into the rocks that compose a mountain or other area are ______ streams. a. bedrock b. tectonic c. shield d. cradle

a. bedrock

Select conditions that have an effect on the flow of river systems over time. a. Climate b. Runoff c. Geology d. Tectonism e. Oil spills f. Dams

a. climate b. runoff c. geology d. tectonism f. dams

Which of the following locations would be the two most common areas in which to find a braided stream or river? a. Flat-bottomed valleys between mountains b. Topographically flat areas such as the Great Plains c. Broad, sloping plains that flank mountain ranges

a. flat bottomed valleys between mountains c. broad, sloping plains that flank mountain ranges.

The area of the origin of a river is its ______, and the ______ the end of the river. a. headwaters; mouth is b. headwaters; tributary is c. mouth; headwaters are d. tributary; headwaters are

a. headwaters; mouth is

Select common features located along low-gradient rivers. a. Single channels b. River terraces c. Steep drainages d. Floodplains e. Waterfalls f. Meanders

a. single channels b. river terraces d. floodplains f. meanders

Which of the following are primary factors that influence a stream's profile? a. Tectonics b. Sea level c. Climate d. Water temperature e. Rock type

a. tectonics b. sea level c. climate e. rock type

Smaller subsidiary channels that feed the main channels of rivers are ______. a. tributaries b. drainage systems c. drainage patterns

a. tributaries

Select consequences to a river when a dam is constructed. a. Water released from the dam is clear (no sediment) and has a new capacity to erode and transport sediments downstream. b. A reservoir is created, providing new and better habitats. c. The dam creates a temporary base level for the river. d. The dam causes the river to deposit its sediment load upstream of the dam.

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

What is a braided stream? a. A stream and its tributaries that form a pattern resembling a tree b. A stream that flows in a network of many interconnected rivulets around numerous bars c. A stream that exhibits a delicate balance between its transporting capacity and the sediment load available to it d. A stream with pronounced sinuous curves

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

Where do deltas form? a. Right above a nickpoint in a meandering river system b. At the mouth of a river that empties into the ocean c. Right below a nickpoint in a braided river system d. Downstream of dams in channelized sections of a stream

b. at the mouth of a river that empties into the ocean.

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

b. braided

The amount of water flowing through a channel over a given amount of time is called its ______. a. rate of flow b. discharge c. drainage basin d. velocity

b. discharge

The two primary forces that drive a river system are ______ and ______. a. tributaries b. gravity c. sediment size d. sediment load e. precipitation f. channel depth

b. gravity e. precipitation

In flowing water, the upstream side of an obstruction is subjected to the ______ of abrasion. a. absence b. greatest amount c. least amount

b. greatest amount

What is stream abrasion? a. A stream getting wider over time due to erosion b. Large grains collide with other grains in a stream and break them into smaller pieces c. The movement of the largest particles on the riverbed during times of high flow

b. large grains collide with other grains in a stream and break them into smaller pieces. (physical weathering)

The size of sediments in braided rivers typically is ______ than that carried by meandering rivers. a. less varied b. more varied

b. more varied

At a flow velocity of 12 cm/sec, which of the following statements are true? a. Gravel is transported as bedload b. Most sand sizes are transported as bedload. c. Silt is transported as bedload. d. Clay is transported as suspended sediment.

b. most sand sizes are transported as bedload. d. clay is transported as suspended sediment.

A depositional feature that has been built on the inside of a stream channel curve because of lower velocity is a ______. a. meander cutoff b. point bar c. mid-channel bar

b. point bar

How does rainwater cause erosion on the ground? a. Rain causes the atoms it hits to become unstable, and this starts radioactive decay. b. Rain causes splash erosion as the drop hits the ground and flows over it, causing sheet erosion. c. Rain causes headwater erosion into the ground. d. Rain absorbs the kinetic energy of the ground and converts it to potential energy.

b. rain causes splash erosion as the drop hits the ground and flows over it, causing sheet erosion.

The total amount of sediment carried by a river is the ______. a. suspended load b. sediment load c. traction load d. saltation load

b. sediment load

When is sediment most likely to be deposited? When the ______. a. tributaries reach the next order of stream in the drainage basin b. sediment supply exceeds a stream's capacity to transport it c. current velocity increases again after a brief slowdown d. grains have a surface area to volume ratio above 2:1

b. sediment supply exceeds a streams capacity to transport it.

At a flow velocity of 100 cm/sec, which of the following statements is true regarding sand-sized sediment? a. All sand-sized particles are transported as suspended sediment. b. Smaller sand grains are transported as suspended sediment, and larger grains are transported as bedload. c. The majority of sand-sized particles are deposited, but the smallest sands are transported as bedload. d. All sand-sized particles are transported as bedload.

b. smaller sand grains are transported as suspended sediment, and larger grains are transported as bedload.

Which of the following describe the headwaters of mountains streams? a. They have the ability to carry small particles only. b. They have turbulent flow. c. Water flow is slow and laminar. d. They have steep gradients. e. They have the ability to carry large boulders.

b. they have turbulent flow. d. they have steep gradients. e. they have the ability to carry large boulders.

A drainage _______ is an area in which all drainages merge into a single stream or move to a single body of water.

basin

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

braided

An oxbow lake is an isolated, curved lake formed when ______. a. a stream floods b. a stream erodes sideways c. a meander is cut off from a stream d. erosion deepens a stream bed

c. a meander is cut off from a stream

What is a point bar? a. A new, shorter channel across the narrow neck of a meander b. A crescent-shaped meander cutoff c. A sandbar deposited along the inside of a stream meander due to lower velocity d. A flowing network of interconnected rivulets around numerous bars

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

Stream terraces are composed of either _______ or ______. a. fine windblown sediment derived from volcanic ash that clumped together after landing in a river b. marine sediments derived from the last high stand of the ocean c. an erosional surface cut into bedrock d. stream-derived sediment composing former floodplains

c. an erosional surface cut into bedrock d. stream derived sediment composing former floodplains

What is the name for the two areas highlighted in this image? a. Drainage divides b. Hydrographs c. Drainage basins

c. drainage basins

Stream terraces not composed of bedrock are likely to have a composition similar to that of a modern ______ in the river system. a. thalweg b. delta c. floodplain

c. floodplain

A stream or river that flows all year is ______. a. a tributary b. ephemeral c. perennial

c. perennial

Sinuosity refers to ______. a. the amount of water passing a point in a river or stream in a given length b. the profile of a river or stream in a given length c. the amount that a river or stream channel curves in a given length d. the steepness of a river or stream in a given length

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

These are formed when a steep drainage enters a broad valley and the sediments and debris are deposited. a. Waterfalls b. Rapids c. Lakes d. Alluvial fans

d. alluvial fans

The lowest level to which a river can erode is its ______. a. headwaters b. sediment capacity c. bedrock d. base level

d. base level

The driving force behind a river's flow is ______. a. its sediment load b. the shape of the riverbed c. its velocity d. gravity

d. gravity

What are bedrock streams? a. The oldest streams within the drainage basin b. Streams that are lined with rocks on the bottom c. The stream within a drainage basin that is most important to the local ecosystem d. Streams that are cutting into the bedrock of the area

d. streams that are cutting into the bedrock of the area.

A(n) ________ is formed where a river meets the sea, slows down, and deposits its sediments.

delta

When rivers enters a lake or an ocean, they slow down and lose their capacity to carry sediments, forming ______. a. cutbanks b. deltas c. point bars d. oxbow lakes e. meanders

deltas

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

deposits

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.

__________ meanders begin as meanders on a floodplain; either the base level drops or a tectonic event causes uplift, followed by more incision, which further deepens the meanders.

entrenched OR incised

Rivers and streams _______ the landscape, carry the materials, and later deposit the sediments, thereby acting as major sculptors of Earth's surface.

erode

Viscosity is the resistance to _______ exhibited by fluids.

flow, movement, OR motion

Rivers are dynamic systems driven by precipitation and _______

gravity

_______ is the force behind a river's flow from high to low elevations.

gravity

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

low

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

lowest OR minimum

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

meandering

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

meters OR feet

What type of lake is created when a cutoff meander becomes isolated? _______

oxbow

Erosion and deposition by ______ are the principal processes that sculpt Earth's landscape.

rivers OR streams

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

sediment, sand, OR load

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

sediments

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

sinuosity

Rainwater creates _______ erosion as it hits the ground.

splash

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

tributaries

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

viscosity

Define the landforms associated with the headwaters of mountain streams.

waterfall:occurs when a stream or rivers gradient is so steep that water goes over a ledge or cliff. rapid: occurs along a river and is characterized by turbulent water. lake: occurs where water is impounded by some obstruction. pool:occurs when water slows down and piles upstream of a rapid.