Qbb2023-test II - Jan 19

30 Questions | By JANUARYUG19 | Updated: Mar 19, 2022 | Attempts: 147

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Questions and Answers

1.

Comparisons between modern and ancient river systems should be carried out with care because continental environments have not changed dramatically through geological time as land plant and animal communities have evolved.
- A.
  
  True
- B.
  
  False
2.

In the transfer zone the streams are actively down cutting, removing bedrock from the valley floor and from the valley sides via downslope movement of material into the stream bed.
- A.
  
  True
- B.
  
  False
3.

Water flow in rivers and streams is normally confined to channels, which are depressions or scours in the land surface that contain the flow.
- A.
  
  True
- B.
  
  False
4.

An alluvial plain is a general term for a low-relief continental area where sediment is accumulating, which may include the floodplains of individual rivers.
- A.
  
  True
- B.
  
  False
5.

When the water level is well below the level of the channel banks it is at high flow stage.
- A.
  
  True
- B.
  
  False
6.

The line of the shallowest part of the channel is called the thalweg.
- A.
  
  True
- B.
  
  False
7.

A braided river contains mid-channel bars that are covered at bank-full flow.
- A.
  
  True
- B.
  
  False
8.

Both braided and anastomosing river channels can’t be sinuous.
- A.
  
  True
- B.
  
  False
9.

Flow is generally lowest between the bars and the coarsest material will be transported and deposited on the channel floor to form an accumulation of larger clasts, or coarse lag.
- A.
  
  True
- B.
  
  False
10.

Where the bedload is deposited as bars of sand or gravel in the channel the flow is divided to give the river a meandering form.
- A.
  
  True
- B.
  
  False
11.

In a gravelly braided river the bar deposits will commonly consist of cross-stratified granules, pebbles or rarely cobbles in a single set.
- A.
  
  True
- B.
  
  False
12.

In plan view the thalweg in a river is not straight even if the channel banks are straight and parallel.
- A.
  
  True
- B.
  
  False
13.

The deposits of a meander bend have a characteristic profile of coarser material at the base, becoming progressively finer-grained up the inner bank.
- A.
  
  True
- B.
  
  False
14.

A point bar deposit will show a fining-up from coarser material at the base to finer at the top.
- A.
  
  True
- B.
  
  False
15.

Erosion occurs on the point bar on the inner side of a bend while deposition occurs on the opposite cut bank.
- A.
  
  True
- B.
  
  False
16.

Levees form when flood waters rapidly deposit sediment close to the bank and crevasse splays are created when the levee is breached.
- A.
  
  True
- B.
  
  False
17.

Chute channels may be semi-permanent features of a point bar, but they are only active during low-stage flow.
- A.
  
  True
- B.
  
  False
18.

A channel is commonly filled with sand: in this case the form of a channel is picked out by steep banks on either side, but the fill of the channel is mainly sand.
- A.
  
  True
- B.
  
  False
19.

. Abandonment of the old river channel will leave it with sluggish water containing only suspended load as all the bedload is diverted into the new course.
- A.
  
  True
- B.
  
  False
20.

Most of the sediment carried out onto the floodplain is suspended load that will be mainly clay- and silt sized debris but may include fine sand if the flow is rapid enough to carry sand in suspension.
- A.
  
  True
- B.
  
  False
21.

If avulsion is frequent, there is less time for lateral migration to occur and the architecture will be characterized by broad channel deposits.
- A.
  
  True
- B.
  
  False
22.

Lateral migration is slowed down if the river banks are not stable.
- A.
  
  True
- B.
  
  False
23.

Alluvial fans form where there is a distinct break in topography between the high ground of the drainage basin and the flatter sedimentary basin floor.
- A.
  
  True
- B.
  
  False
24.

The fan apex is the lowest, most proximal point adjacent to the feeder canyon from which the fan form radiates.
- A.
  
  True
- B.
  
  False
25.

Bay head delta: Is the zone where fluvial processes are dominant. As the river flow enters the central lagoon it decelerates and sediment is deposited.
- A.
  
  True
- B.
  
  False