Landforms by River Archives

11. Which one of the following is not a fluvial landform?

Which one of the following is not a fluvial landform?

Cirque

Gorge

Braids

Canyon

This question was previously asked in

UPSC CDS-2 – 2020

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Fluvial landforms are geological features created by the action of flowing water, primarily rivers and streams. Gorges and Canyons are deep valleys carved by river erosion. Braids, specifically braided channels, are a type of river morphology characterized by multiple interwoven channels formed by the deposition and erosion of sediment by the river. A Cirque (also known as a corrie or cwm) is a bowl-shaped depression carved into a mountain side by glacial erosion, specifically at the head of a glacier. Therefore, a Cirque is a glacial landform, not a fluvial one.

– Fluvial landforms are shaped by rivers.
– Gorge, Canyon, and Braids are landforms created by rivers.
– A Cirque is a landform created by glaciers.

Examples of other fluvial landforms include V-shaped valleys, floodplains, meanders, oxbow lakes, deltas, alluvial fans, levees, and waterfalls. Glacial landforms include U-shaped valleys, moraines, drumlins, eskers, and tarns.

12. Which of the following statements regarding river meanders is/are corr

Which of the following statements regarding river meanders is/are correct?

1. It is a U-shaped bend in a river.
2. An extremely tight meander is called a gooseneck; it is likely to become a cutoff, or oxbow lake, after a flood.
3. Tectonic uplift can cause a river to continue downcutting along its meandering course, producing incised or entrenched meanders.

Select the correct answer using the code given below.

1 only

1 and 2 only

2 and 3 only

1, 2 and 3

This question was previously asked in

UPSC CDS-1 – 2024

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All three statements regarding river meanders are correct.

River meanders are natural sinuous bends formed in a river channel. They evolve over time and can be affected by geological processes like tectonic uplift. Tight meanders can be cut off during floods, forming oxbow lakes.

1. A meander is indeed a U-shaped or loop-like bend in the course of a river or stream.
2. A tightly curved meander loop with a narrow neck is often termed a gooseneck or incised meander loop. During high flow events (floods), the river can erode through the narrowest part of the neck, creating a new, shorter channel (a cutoff) and isolating the former meander loop as an oxbow lake.
3. If tectonic forces cause the land surface to be uplifted relative to the river’s base level, while the river continues to flow in its established meandering course, the river will erode downwards (downcut) into the uplifting bedrock. This process creates incised or entrenched meanders, which are meanders cut deeply into the landscape with steep valley walls.

13. Statement I: Incised meanders are formed in the mature stage of a rive

Statement I:
Incised meanders are formed in the mature stage of a river.
Statement II:
Incised meanders are characterized by rejuvenation and upliftment of land.

Both the statements are individually true and Statement II is the correct explanation of Statement I

Both the statements are individually true but Statement II is not the correct explanation of Statement I

Statement I is true but Statement II is false

Statement I is false but Statement II is true

This question was previously asked in

UPSC CDS-1 – 2018

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Statement I is false. Incised meanders are typically formed when a river that has already developed meanders on a floodplain (characteristic of the mature stage) experiences rejuvenation. Rejuvenation can be caused by processes like tectonic uplift of the land or a drop in the base level (e.g., sea level). This allows the river to cut downwards into its existing meandering channel, rather than eroding laterally across a floodplain. Statement II is true; incised meanders are specifically associated with the rejuvenation and uplift of the land, which increases the river’s erosive power.

River stages are often simplified into youthful, mature, and old. Meanders typically form in the mature stage on flatter terrain. Rejuvenation introduces a new cycle of erosion, causing vertical cutting even in a meandering course, leading to incised meanders.

Incised meanders can be either ‘entrenched’ (symmetrical valley sides, often due to rapid uplift or deep cutting) or ‘ingrown’ (asymmetrical valley sides, where some lateral erosion continues alongside vertical cutting). They are evidence of a change in the river’s energy regime after the initial meandering pattern was established.