Geo - Units 38 - 41

What is the discharge of a river with a depth of 10 meters, width of 5 meters and a flow velocity of 5 meters/second?

250 m 3/sec

What is the discharge of a river with an average depth of 2 meters, width of 3 meters and a flow velocity of 5 meters/second?

30 m3/sec

The most important force driving erosion and transportation of eroded rock material into a new site of deposition is:

Earth's gravity

A flood with a recurrence interval of 100 years means that the flood occurs every 100 years

False

According to John Hack, landscapes are in dynamic equilibrium when the slopes of hills and valleys change over time

False

An area consisting of mudstones and shales will likely exhibit steeper slopes than those composed of hard metamorphic and igneous rocks:

False

Deltas commonly form where a stream empties into larger streams T or F

False

Erosion by rivers and road construction are examples of factors that may cause a decrease in slope angles thereby promoting mass movements.

False

Perched water tables occur below the main water table.

False

Percolation in the vadose zone increases as soil becomes more compacted.

False

Runoff, water moving over land surfaces, occurs when infiltration rates exceed the amount of water falling.

False

Stream capture usually results when two adjacent streams flood producing a single new stream

False

Stream discharge do not influence the shape or form of the delta. T or F

False

The potential energy of water is greater in low lying areas than high relief areas.

False

Water in a river with a large suspended load is more competent than a river moving large boulders.

False

Ephemeral streams flow year round

False.

Fluvial landforms are all formed by stream erosion.

False.

Usually, after flood control measures have been undertaken, it is safe to farm and build on a flood plain.

False.

Identify the erosional landform developed by streams.

Grand Canyon

______ occurs when raindrops fall on vegetation and evaporates before penetrating the soil.

Interception

Topography that can be distinguished and studied as a single unit is a:

Karst topography

Perched water tables occur above the main water table

True

Percolation in the vadose zone increases as soil becomes wetter.

True

The role of climate in influencing the development of landscapes is debatable. Generally, humid environments have more rounded landforms and desert environments have angular ones

True

Waves, tides and currents influence the shape or form of the delta. T or F

True

Runoff, water moving over the land surface, occurs when the amount of water falling exceeds infiltration rates

True.

What two factors determine stream discharge?

Velocity and cross-sectional area of stream

_____ is a natural geologic process that breaks down rock.

Weathering

Which would you expect to have a higher sediment yield?

a drainage basin with steeper gradients.

If the sediment supply to a river increases so much that it overwhelms the ability of the stream to carry the sediment, then _____ will occur.

aggradation.

The resistance of geologic materials to movement, also known as their frictional strength, depends on:

all of the above type of material weight of overlying block the amount of water present

Where is a stream's load deposited?

all of the above.

Which of the following influences rates of erosion in the drainage base?

all of these

Infiltration capacity depends on which of the following?

all of these vegetation coverage dryness or wetness of soils intensity and duration of rainfall land use such as cattle grazing

The Black Hills of South Dakota exhibit _____ drainage.

annular

Perched water tables are separated from the main aquifer by:

aquicludes.

Groundwater is stored in:

aquifers

Creep involves movement of soil:

at a slow, almost imperceptible pace

The downslope movement of material is termed mass movement. What type of mass movement involves snow and ice?

avalanche

When juxtaposed alluvial fans join along a mountain front obscuring their the cone shapes, a(n) _____ forms.

bajada or alluvial apron

Saltating sand is part of the

bedload

The Mississippi Delta is an example of a(n) _____ delta

birdfoot.

Areas of high relief tend to have:

both (a) and (b) high rates of erosion steep slopes

Fragments that accumulate near their original location can form:

both (b) and (c) blockfields? ice sheets? talus?

Factors influencing the velocity of a stream include

both a and b.

Which condition could lead to drawdown below the level of existing wells?

both a and c growth of population in an area using water for agricultural purposes

Extrusive igneous structures include:

both a and c.

Weathering is the:

breakdown of rocks and minerals into smaller particles

The formation of underground caverns occurs through the ____ process.

carbonation

Which is typically the least important form of stream erosion?

corrosion

For what is William Morris Davis known?

cycle of erosion.

Which process is common in alluvial fan deposits?

debris flows

High water content in soil or fractured rock will:

decrease slope stability

When rivers deposit sediments along the coast, these can form:

deltas

Which drainage pattern is common in the Midwest, such as with the Missouri and Ohio Rivers?

dendritic.

A recent development in the measurement of erosional rates is:

determining how much sediment is transported by rivers

The gradient or slope of a stream is calculated by:

dividing the change in elevation of two points of a stream by the stream length between those two points

The material that has the least cohesion is:

dry sand

As landscapes become steeper, these processes work more quickly to wear down the landscapes

erosional

As landscapes become steeper, these processes work more quickly to wear down the landscapes:

erosional

Smaller materials can be transported from one location to another by _____ processes.

erosional

In order to distinguish the difference between a slide and a slump, a geologist would:

examine the surface in which blocks of rock move down

Which of the following holds the greatest amount of freshwater?

glaciers and ice sheets

All of the following factors increase shear stress and trigger slope failure EXCEPT:

grading steep slopes into step-like structures

A main driving force for mass movements is:

gravity

Volcanic remnants like Shiprock, NM are much smaller than the volcanoes of the Cascade Mountains because they

have been dormant and erosion has worn away most of its mass

Freeze-thaw mechanical weathering can occur year-round in ____ environments.

high altitudes, such as mountain

The Badlands exhibit

high drainage density

Most intense chemical weathering occurs in _____

humid, tropical areas

Most intense chemical weathering occurs in _____.

humid, tropical areas

The amount of water that falls to the surface in a given time period is termed:

intensity

What is weathering's role in the rock cycle?

it breaks down rocks into sediments

Flood deposits made up of the coarsest material form a(n) ___ along the flooded river.

levee.

A spontaneous downslope movement of Earth material is called:

mass movement

What type of weathering is associated with the freezing of water in the joints of rocks?

mechanical weathering

Which of the following is more likely to underlie valleys?

mudstone

Which part of a stream would you expect to find the largest discharge?

near a bend

In which sphere is water not present?

none of the above atmosphere biosphere lithosphere hydrosphere

Where on a meandering river is erosion the greatest

on the outside

Which of the following is NOT a type of mass movement?

ooze

What kind of lake forms when a meander is cut off?

oxbow lake.

Which of these is NOT a form of mechanical weathering?

oxidation

Of the minerals listed, which is the most resistant to chemical weathering?

quartz

Which drainage pattern is typical of the Cascade Mountains?

radial.

When iron-bearing silicate minerals are broken down by weathering, the iron through oxidation produces a:

reddish-brown or orange colored rock

Erosion leads to the reduction of the ____ of landmasses.

relief

The most effective and significant agent of erosion globally is:

running water

The growth of _____ crystals in arid regions has similar effects on rocks as do frost action in cold regions.

salt

Which material exhibits the greatest infiltration rates?

sandy soil.

Slumps are common in:

shale and clay-rich rocks

The component of gravity tending to push blocks of rock downhill parallel to the slope is termed:

shear stress

Meandering channels are:

sinuous

A snow avalanche is considered what form of mass movement?

slide

What feature is present where the water table intersects the Earth's surface?

spring

Commonly, a river is said to be graded when the longitudinal profile is _________and neither _______ or _______occurs.

stable; aggradation; erosion of channel floor.

Rates of erosion would be greater in:

steep mountains

Stream terraces are formed when

streams cut into their own deposits

Which typically carries the greatest amount of river sediment load?

suspended load

Folding and uplifting of rocks to form mountains, and the addition of new rock through volcanic eruptions are products of:

tectonic activity

Slope failure will occur when materials exceed _____

the angle of repose

Water interception by vegetation depends in part on:

the structure of the plants.

Which drainage pattern is typical in the Appalachian Ridge and Valley Province?

trellis.

The upper unsaturated zone in the ground is termed the

vadose zone.

All of the following are erosional agents in shaping the landscape EXCEPT:

volcanic eruptions

Most chemical weathering involves:

water

Deposition on an alluvial fan occurs:

when the flow is no longer confined to the river walls.

Alluvial fans form ________.

where streams emerge from the mountains.