Geology 1403 Unit 4

The Mississippi River is the only North American river to rank the top ____. It is the biggest in America and the ____ biggest in the world

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______ fracturing allows for greater porosity and permeability.

Abundant

Streams typically do not meander if they are _______ ____.

Actively Downcutting

Stream deposited sediment is called _______.

Alluvium

The _____ River in Brazil is the largest river int eh world in terms of discharge.

Amazon

An _____________ contains groundwater and is both porous and permeable.

Aquifer

______ are both porous and permeable zones within Earth containing groundwater.

Aquifers

_______ (or aquicludes) may have good storage capacity (porosity), but are impermeable (they retard the flow of water).

Aquitards

River erosion is generally dominated by downcutting as long as the bottom of the channel is above _____ level.

Base

_____ level is the maximum depth a stream can cut down to.

Base

A stream cannot downcut any deeper if it has reached _____.

Base level

Sediment traveling in a stream by traction and/or saltation is considered the _____________ of the stream.

Bed Load

_____________ streams tend to develop in areas where an abundance of bedload is deposited.

Braided

______ _______ develop in regions where a stream carrying an abundance of bed load losses velocity resulting in deposition of sand and gravel within the channel. (eg. The Great Sand Dunes)

Braided Streams

Little or no _______ holding particles together allows for greater porosity and permeability

Cement

______ encourages the water to move through an area more quickly.

Channelization

A _______ is where two streams join

Confluence

The junction where two streams join together is called a ______.

Confluence

These graphs show that as stream discharge increases, not only does the depth and width of the ____ ______ area increase, but so does the velocity of the water.

Cross Sectional

Discharge is typically described in units of _____ _____ ___ _______ (CFS).

Cubit Feet Per Second.

What do you call the outside bank of a meander loop?

Cut Bank

Erosional floodplains are the result of lateral erosion occurring on the outside of a bend in the stream, called the ____ ____, and deposition of sediment on the inside of the bend, called a ____ ____. The higher velocity on the outside of a bend allows for _____, while the slower velocity on the inside of the bend allows for _______. This combination of erosion on the outside and deposition on the inside of a channel results in the bends, called _______, of the stream continuing to enlarge through time. This enlargement creates broad meander _____ and the overall widening of the river valley.

Cut Bank Point Bar Erosion Deposition Meanders Loops

When sediment is deposited into a body of water at the mouth of a river, the accumulation may build up into a _____.

Delta

A ______ drainage pattern typically develops on horizontal layers of sedimentary rock, or hard crystalline bedrock such as igneous or metamorphic. They drainage patterns are the most common of all. (They are shaped like trees).

Dentric

The most common drainage pattern,________________, typically develops on hard, crystalline rocks or flay-lying sedimentary rocks.

Dentric

These graphs show that as stream discharge increases, not only does the _____ and _____ of the cross sectional area increase, but so does the velocity of the water.

Depth Width

A stream handles an increase in _________ by increasing depth, width, and velocity.

Discharge

One way to express the size of a river or stream is by its _______.

Discharge

The quantity of water a stream is carrying is known as its _____.

Discharge

Abundant ______ (if possible) allows for greater porosity and permeability.

Dissolution

The _________________ load is invisible.

Dissolved

The branching streams on a delta are called _____________ channels.

Distributaries

River erosion is generally dominated by _______ as long as the bottom of the channel is above base level.

Downcutting

Running water may erode the land by ______ or by lateral erosion.

Downcutting

Dams can generally control flooding _____.

Downstream

Levees help prevent flooding in the immediate area, but encourages flooding ______.

Downstream

The ________ area is the amount of land surface that is drained by a given river system.

Drainage

Divides separate _______ basins and _____ sheds.

Drainage Water

The turbulence also creates _____ in which the water is swirling around but not really moving down the channel very rapidly.

Eddies

Rejuvenation of a meandering stream may allow it cut deep into its channel forming _________ and ______ meanders. They are the same thing.

Entrenched and Incised

Running water _____, ______, and ______ sediment.

Erodes Transports Deposits

The gradient near the mouth of a stream is generally much less, therefore gradient supports ______ flow in the headwaters.

Faster

When a stream changes direction, water flows _________ on the outside of the bend.

Faster

As a wide river valley is created by lateral erosion, a _______ develops along the sides of the channel.

Floodplain

_____ _____ are highly variable, but commonly on the order of a few inches a day.

Flow Rates

Groundwater flows into a _______ stream, whereas a losing stream loses water to groundwater.

Gaining

Overall, most streams are ______ streams.

Gaining

The hydraulic ______ is the slope of the water table over a given distance.

Gradient

Due to _______ and additional tributaries feeding into stream channels, discharge tends to increase as you move toward the mouth causing an increase in velocity.

Groundwater

What is our largest source of readily available fresh water?

Groundwater

_______ is the largest reservoir (94%) of fresh water readily available to humans

Groundwater

Most Texas rivers drain directly into the ________ of _______.

Gulf Mexico

_____ erosion is the idea that streams may erode in the headward direction of the stream. It may cause stream piracy.

Headward

Shallow channels are more common in _______ regions.

Headwaters

Since the headwaters of most major streams originate in mountainous regions, gradients are usually ______ in the headwaters.

Higher

Where do streams downcut?

In the bottom of the channel

6. Groundwater flow rates are generally on the order of __________ per day.

Inches

Due to groundwater and additional tributaries feeding into stream channels, discharge tends to ______ as you move toward the mouth causing an increase in velocity.

Increase

As stream discharge ______ , not only does the depth and width of the cross sectional area increase, but so does the velocity of the water.

Increases

In a humid region water (from rain and snowmelt) _______ into Earth until it hits a "confining unit."

Infiltrates

Sediment size tends to decrease downstream allowing more _____ flow (and higher velocity) from the smoother channel near the mouth of a river.

Laminar

_______ grain sizes allow for greater porosity and permeability.

Larger

Running water may erode the land by downcutting or by ______ erosion.

Lateral

When a stream reaches base level and can no longer downcut, ______ erosion will widen the stream channel through time.

Lateral

Successive flooding may build up deposits along the sides of the channel. These deposits are called natural _______.

Levees

_______ compacted grains allows for greater porosity and permeability

Loosely

Rivers and streams exist because there is ______ precipitation on land than evaporation on land.

More

Deep semi-circular channels are more common near the _____ of a river.

Mouth

The gradient of a stream typically deceases as you move from the headwaters of the stream toward its _______.

Mouth

With a sufficient load a delta builds up at the ___________ of a river.

Mouth

In arid mountainous regions streams may bring a lot of bed load down to the _____ of the valley. The loss of the confining valley &/or reduction of _____ allows sediment to accumulate here. Over time the sediment builds up into a semi-circular (___-shaped) form. Hence, this landform is called an alluvial fan.

Mouth Slope Fan Alluvial

Combining all the factors considered, it turns out that most streams have a higher velocity near their _____, rather than in the steeper ________.

Mouth Headwaters

Where is stream velocity generally the highest?

Near the Mouth

In a hundred year floodplain there is a __________ % chance that area will be flooded each year.

One

_____ flooding occurs when a river spills out of its banks.

Overland

Meander loops may eventually get cut off forming a(n) _________ lake.

Oxbow

Flow rates depend on the hydraulic gradient and the _______.

Permeability

The property of rock or sediment that determines the ease of groundwater flow is called _______.

Permeability

The slower velocity on the inside of a bend results in a deposit known as a _______.

Point Bar

______ is storage capacity.

Porosity

The bottom of the stream channel is often marked by ______.

Potholes

____________ are direct evidence that downcutting has been occurring.

Potholes

_______ comes from moisture that has been evaporated into the atmosphere by the sun.

Precipitation

Urbanization ______________ flooding because it allows runoff to enter a stream more quickly.

Promotes

Discharge is the ________ of water that flows through the channel in a given amount of time.

Quantity

A ______ drainage pattern is typical when streams develop on a conical hill or mountain, such as a volcanic cone

Radial

What type of drainage would be typical on a volcano?

Radial

The discharge of a stream can change daily and seasonally due to a number of factors such as _______ and _________ amounts, etc.

Rainfall Snowmelt

The water is often very turbulent with many ______, _______, and ______ pools.

Rapids Waterfalls Plunge

A________ drainage pattern often develops in an area where the bedrock has been fractured. The

Rectangular

Typical mountain (headwater) stream with rough channel causing _____ in velocity.

Reduction

The precipitation over the oceans is less than the evaporated over the ocean, so river runoff is simply "__________" the water that evaporated over the oceans, but precipitated over the land.

Returning

______ ______ refers to all water that comes into a river water system from sources such as rainfall, snowmelt and groundwater.

River Runoff

A river that is dominated by active downcutting generally cuts a deep, narrow ____ ____.

River Valley

The Continental Divide runs down the heart of the ___________ Mountains.

Rocky

The _____ the channel (the more large gravel in the stream bed), the lower the velocity because the water has to flow over and around so many obstacles.

Rougher

The water table separates the zone of _______ from the zone of _______.

Saturation Aeration

Although only a fraction of a percent of all water on Earth, running water does more to ______ Earth's surface than any other agent of erosion.

Sculpt

Which stream shape allows water to flow faster?

Semi-Circular

Stream gradient is the _____ of the stream channel.

Slope

A _____ _____ is a very deep, narrow river valley formed by active downcutting into a coherent, solid rock body.

Slot Canyon

______ shapes allow for greater porosity and permeability

Spherical

____ _____ is the slope of the stream channel.

Stream Gradient

_____ ______ is where one stream robs the water from another stream.

Stream Piracy

The water table may fluctuate with dry and wet seasons but is generally a s______ ______ of the topography.

Subdued Replica

A(n) ______________ stream originated above the resistant rock it cuts through.

Superposed

The stream may be _____ above resistant units and cut down into them or they may be _______. This means they were there before structural deformation occurred.

Superposed Antecedent

The _________________ load typically makes the water muddy.

Suspended

If a stream cannot cut down below a certain point along its path, the elevation of that point becomes a ______ base level for the stream above that point.

Temporary

As streams cut into floodplain sediments and then widens the downcut area, stream _____________ may form.

Terraces

A ______ drainage pattern forms in a region where there are a series of (near) parallel hills and valleys.

Trellis

A region containing a series of parallel hills and valleys would most likely have a _______________ drainage pattern.

Trellis

A smaller stream the feeds into a larger stream is called a ______ stream

Tributary

What do you term a smaller stream that flows into a larger stream?

Tributary

If a stream's water eventually flows into the sea, sea level is its ______ base level.

Ultimate

A stream that is actively downcutting typically has developed a deep _____________ profile.

V

The valley is generally ____________, and the river typically runs a relatively straight course .

V Shaped

Discharge can be calculated by measuring the cross-sectional area of the steam cannel (average width x average depth) and multiplying it by the average _______ of the water. (Discharge = WxDxVelocity)

Velocity

For sand and gravel a higher _____ is required to move a larger size of particle.

Velocity

There is less frictional resistance in a deep semi-circular channel than in a shallow-wide channel. This allows for a higher _____ in the semi-circular channel.

Velocity

What a stream is doing at a given time is based primarily upon the ______ of the water and _____ of particle.

Velocity Size

The _____ River in Zion National Park, Utah has actively downcut into the sandstone formations of the region creating this narrow river valley.

Virgin

A _______ gap is simply an abandoned water gap.

WInd

When a river cuts through a resistant unit of rock, it forms a _____.

Water Gap

_____ ____ are formed when a stream cuts through resistant rock units that form hills or mountains.

Water Gaps

3. The ______ can fluctuate due to seasons of drought or seasons of abundant rain or snow.

Water Table

If unconfined, the _______________ is typically a subdued replica of the shape of the land.

Water Table

The _________ is the boundary between the zone of saturation and zone of aeration.

Water Table

The upper limit of saturation is called the _____ _____.

Water Table

_________ materials (all particles are about the same size) allows for greater porosity and permeability

Well-sorted

Because natural levees tend to isolate the channel from the floodplain, ________ tributaries and backswamps are commonplace.

Yazoo

There is a ____% chance of flooding in a 20 year floodplain.

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