Earth: an Introduction to Physical Geology, 9E (Tarbuck/Lutgens)

Chapter 16 Running Water

Earth: An Introduction to Physical Geology, 9e (Tarbuck/Lutgens)

16.1

Multiple-Choice Questions

________ is not part of the hydrologic cycle.

Water evaporating from a lake

Water infiltrating into the soil and bedrock

Calcium carbonate dissolving in soil water and groundwater

Water moving into creeks and streams following a rainstorm

Answer:

Diff: 1

Which one of the following statements is correct?

Sea level drops when water is stored in expanding ice sheets and continental glaciers.

Sea level rises when water is added to the oceans through increased rainfall and increased inflow from rivers.

Sea level drops when evaporation rates increase over the oceans and when this extra, atmospheric moisture falls on land as rain.

Sea level rises when water is stored in expanding ice sheets and continental glaciers.

Answer:

Diff: 1

Which of the following is the correct definition of stream gradient?

the distance traveled by water in a channel times a drop in elevation

the drop in elevation of a stream divided by the distance the water travels

the water pressure at the bottom of the stream divided by the stream's width

the increase in discharge of a stream per unit drop in elevation

Answer:

Diff: 1

A natural, meandering, river channel is modified into a more or less straight and smooth, canal-like channel. Which of the following statements is correct?

The natural channel had a lower gradient and less friction than the modified channel.

The straight channel has a higher gradient and more friction than the natural channel.

The natural channel had a lower gradient and higher friction than the straight channel.

All of the above statements are true.

Answer:

Diff: 2

How does urbanization (paving, etc.) affect runoff and infiltration in a small, previously forested, drainage basin?

both decrease

runoff decreases; infiltration increases

both increase

infiltration decreases; runoff increases

Answer:

Diff: 1

Which of the following must result in a lower base level for rivers and streams?

sea level drops; land subsides

sea level falls; land rises

sea level rises; land subsides

sea level rises; land rises

Answer:

Diff: 2

________ make up the suspended loads of most rivers and streams.

Dissolved ions and sand

Dissolved salts

Silt and clay-sized, detrital grains

Sand and gravel that move during floods

Answer:

Diff: 1

________ describes the total sediment load transported by a stream.

Capacity

Discharge

Competence

Hydro-load factor

Answer:

Diff: 1

At the head of a delta, the major channel splits into smaller channels that follow different paths to the sea. These smaller channels are known as ________.

endotributaries

exotributaries

distributaries

cotributaries

Answer:

Diff: 1

10)

Why is a bird-foot delta like that of the present-day Mississippi below New Orleans likely to change naturally toward one with the shape of an equilateral triangle like the upper-case, Greek letter delta (D)?

Present-day distributaries have higher gradients than potential new ones.

Potential, new, major distributary channels have steeper gradients than existing channels.

Potential, new, distributary channels have higher gradients, causing downcutting of the existing channels.

Increased sediment loads since the mid-19th century have caused the major distributaries to be filled with sand.

Answer:

Diff: 2

11)

In the absence of cutoff, how does a river meander loop behave over time?

The gradient is raised as the loop lengthens, and the channel migrates toward the cut or inner bank of the loop.

The gradient is raised as the loop shortens, and the channel migrates away from the cut or outer bank of the loop.

The gradient is lowered as the channel lengthens and migrates toward the cut or outer bank of the loop.

The gradient is lowered as the loop shortens, and the channel migrates toward the cut or inner bank of the loop.

Answer:

Diff: 2

12)

A ________ stream pattern is developed only on growing mountains like volcanoes or where the land surface is tectonically doming upward.

radial

dendritic

boreal

trellis

Answer:

Diff: 1

13)

A ________ stream pattern develops on lands underlain by tilted or folded, alternating hard and soft, sedimentary strata.

dendritic

radial

trellis

boreal

Answer:

Diff: 1

14)

________ is an abandoned, cutoff, meander loop.

A builtrail

An oxbow

A cowhock

A gatorback

Answer:

Diff: 1

15)

________ are characteristics of downcutting streams and a youthful stage of valley evolution.

Rapids and lots of whitewater

Wide floodplains

A U-shaped, cross-valley profiles

Meandering channels and natural levees

Answer:

Diff: 1

16)

Many larger rivers in the Colorado Plateau region meander in deep, narrow canyons and have no floodplains. How could this happen?

Original, youthful streams continued to downcut as the land rose.

Original, old age streams downcut as the land gradually rose.

As sea level dropped, the original youthful streams matured into old-age streams.

As sea level rose, the original, old age streams were rejuvenated.

Answer:

Diff: 1

17)

A water gap is ________.

a low sag between adjoining segments of a natural levee

the narrow strip of land separating two meander loops

a vertical-walled canyon resulting from very rapid stream downcutting

a short segment of canyon formed where a river flows across the outcrop area of a resistant, ridge-forming rock layer

Answer:

Diff: 1

18)

Which of the following is the only correct response concerning the location and causes of the extraordinarily severe, 1993, flooding on the Mississippi River and tributaries?

lower basin; heavy rains in late spring and early summer

upper basin; rapid melting of an unusually deep snow pack in early spring

lower basin; very heavy, late summer rains associated with a severe hurricane

upper basin; very heavy, sustained rainfall in the late spring and early summer

Answer:

Diff: 1

19)

Which one of the following statements correctly describes how stream terraces can form?

Base level drops; the stream aggrades its channel, and the former floodplain is left below the present elevation of the stream.

A temporary base level is eliminated; the stream downcuts upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream.

Base level rises; the stream downcuts, and the old floodplain is left well above the elevation of the present-day channel.

A temporary base level is eliminated; the stream aggrades its channel upstream from the old temporary base level, and the former floodplain is left well above the present elevation of the stream.

Answer:

Diff: 2

20)

________ are components of the hydrologic cycle that release water vapor directly to the atmosphere.

Runoff and infiltration

Evaporation and transpiration

Precipitation and runoff

Discharge and transportation

Answer:

Diff: 1

21)

What is the drop in water surface elevation divided by the distance the water flows?

stream discharge

hydraulic capacity

hydrologic resistance

stream gradient

Answer:

Diff: 1

22)

The ________ river has the largest discharge of any in the world.

Nile

Mississippi

Congo

Amazon

Answer:

Diff: 1

23)

Which one of the following does not apply to stream turbulence and average velocity?

channel shape; bed roughness

laminar flow; dissolved load

discharge; stream gradient

stream gradient; channel roughness

Answer:

Diff: 1

24)

Which one of the following is true concerning a major river system?

Upstream tributaries generally have lower gradients than the major river.

Channel bed roughness and turbulence generally increase downstream.

Upstream tributaries generally have higher competencies than the major river.

Discharge decreases below junctions with perennial tributaries.

Answer:

Diff: 1

25)

________ generally constitutes the highest percentage of the annual sediment load moved by a stream.

Bed load

Dissolved load

Suspended load

Saltation load

Answer:

Diff: 1

26)

Where is erosion concentrated along a meandering stream?

on the straight channel segments that connect the meander loops

on the outer parts of the meander loops or bends

at the unconsolidated point bars

on the inner banks of the meander loops

Answer:

Diff: 1

27)

Which one of the following would cause stream rejuvenation?

sea level rises

a shift from downcutting to lateral cutting

the land is uplifted

when unstable distributaries in a delta are abandoned

Answer:

Diff: 1

28)

Which one of the following statements is true concerning natural levees?

Depositional features formed at times of low discharge.

Mostly fine sand and silt that build up during floods.

Erosional features left behind when meander cutoff occurs.

Form the high, steep banks of a downcutting stream.

Answer:

Diff: 1

29)

In a ________ drainage pattern that is generally developed in areas underlain by tilted or folded strata, tributary streams flow along outcrop areas of the softer strata.

trellis

dendritic

coparallel

radial

Answer:

Diff: 1

30)

A ________ drainage pattern is common in the Appalachian Valley and Ridge Province.

dendritic

polygonal

circular

trellis

Answer:

Diff: 1

31)

A stream begins at an elevation of 200 meters and flows a distance of 400 kilometers to the ocean? What is the average gradient?

2 m/km

2 km/m

0.5 m/km

0.5 km/in

Answer:

Diff: 1

32)

________ in a delta are essentially cross strata inclined toward deeper water.

Backset beds

Topset beds

Foreset beds

Bottomset beds

Answer:

Diff: 1

33)

The ________ describes the movement of water through Earth's hydrosphere.

aqualytic cycle

aquatic cycle

precipitation cycle

hydrologic cycle

Answer:

Diff: 1

34)

________ describes the particle transport mode in streams intermediate between suspension and rolling along the bottom?

Siltation

Alluviation

Impact leaping

Saltation

Answer:

Diff: 1

35)

Which of the following features characterize wide streams and valleys?

natural levees; broad floodplains

rapids; channel bed potholes

waterfalls; entrenched meanders

V-shaped valley cross-sections

Answer:

Diff: 1

36)

Entrenched meanders are evidence for what sequence of geologic events?