Important MCQs Related to Geological works by Glacier With Explanations -2

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16. What is the firn line in a glacier?

A) The line marking the glacier's terminus
B) The boundary between snow and ice within the glacier
C) The elevation where accumulation equals ablation
D) The area of maximum ice flow velocity

Answer: C) The elevation where accumulation equals ablation
Explanation:
The firn line, or equilibrium line, is the boundary where snow accumulation equals ice melting and sublimation over a year. Above this line, there is net accumulation, and below it, net loss.


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17. How do glaciers contribute to isostatic rebound?

A) By adding pressure to tectonic plates
B) By carving deep valleys that change the Earth’s crust
C) By removing ice weight, causing the crust to rise
D) By depositing heavy sediment on the crust

Answer: C) By removing ice weight, causing the crust to rise
Explanation:
Isostatic rebound occurs after glaciers melt and the weight of the ice is removed, allowing the Earth's crust to slowly rise back to its original position.


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18. What are erratics in glacial geology?

A) Large boulders carried and deposited by glaciers
B) Ice blocks left behind after a glacier retreats
C) Steep ridges formed by glacial erosion
D) Depositional features formed by meltwater

Answer: A) Large boulders carried and deposited by glaciers
Explanation:
Erratics are large, out-of-place boulders transported and deposited by glaciers, often composed of rock types different from the local geology.


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19. What is the main characteristic of a U-shaped valley?

A) A steep-sided, narrow valley with a flat bottom
B) A deep gorge with V-shaped cross-section
C) A narrow ridge separating two valleys
D) A shallow depression formed by wind erosion

Answer: A) A steep-sided, narrow valley with a flat bottom
Explanation:
U-shaped valleys are formed by the erosive action of glaciers, which widen and deepen pre-existing V-shaped river valleys into a more rounded, flat-bottomed profile.


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20. Which of the following features is a kettle?

A) A small hill formed by glacial deposits
B) A bowl-shaped depression formed by melting ice blocks
C) A ridge formed by meltwater streams
D) A deep gorge carved by a glacier

Answer: B) A bowl-shaped depression formed by melting ice blocks
Explanation:
Kettles are depressions formed when large blocks of ice left behind by a retreating glacier melt, leaving holes that may later fill with water to form kettle lakes.




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21. Which feature indicates glacial deposition rather than erosion?

A) Arête
B) Roche moutonnée
C) Till plain
D) Hanging valley

Answer: C) Till plain
Explanation:
Till plains are flat areas of unsorted glacial debris deposited by the melting glacier, contrasting with erosional features like arêtes or hanging valleys.


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22. What is the term for a sharp mountain ridge formed by glacial erosion?

A) Drumlin
B) Esker
C) Arête
D) Cirque

Answer: C) Arête
Explanation:
An arête is a sharp, narrow ridge formed when two adjacent glaciers erode a mountain from opposite sides, leaving a steep, knife-edge crest.


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23. What is the primary difference between continental glaciers and alpine glaciers?

A) Size and location
B) Composition of ice
C) Rate of movement
D) Type of sediment deposited

Answer: A) Size and location
Explanation:
Continental glaciers, like ice sheets, cover vast areas of land and are found in polar regions, whereas alpine glaciers are smaller and confined to mountain regions.


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24. What is the zone of accumulation in a glacier?

A) The area where ice melts faster than it accumulates
B) The area where snow and ice build up over time
C) The area where glacial ice flows fastest
D) The terminus of a glacier

Answer: B) The area where snow and ice build up over time
Explanation:
The zone of accumulation is the upper part of a glacier where annual snowfall exceeds melting and sublimation, leading to ice growth.


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25. What is the primary cause of glacial striations?

A) Melting of the glacier
B) Abrasion of bedrock by rocks embedded in the glacier
C) Freezing and thawing of water under the glacier
D) Chemical weathering of the underlying rock

Answer: B) Abrasion of bedrock by rocks embedded in the glacier
Explanation:
Glacial striations are grooves or scratches in bedrock caused by rocks and debris embedded in the glacier as it moves over the surface.


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26. Which of the following is an example of a proglacial lake?

A) A lake formed in a cirque after glacier retreat
B) A lake formed by meltwater dammed by a moraine
C) A lake formed beneath a glacier
D) A lake formed by volcanic activity

Answer: B) A lake formed by meltwater dammed by a moraine
Explanation:
Proglacial lakes are formed when meltwater from a glacier is trapped by a moraine or other glacial deposits, creating a temporary or permanent body of water.


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27. What is the term for water that flows beneath a glacier?

A) Glacial runoff
B) Subglacial meltwater
C) Esker stream
D) Groundwater flow

Answer: B) Subglacial meltwater
Explanation:
Subglacial meltwater flows beneath a glacier due to melting caused by pressure and geothermal heat, often creating tunnels and depositional features like eskers.


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28. What is the primary factor determining the velocity of a glacier?

A) Temperature fluctuations
B) Slope of the underlying land
C) The size of the glacier
D) The latitude at which the glacier is located

Answer: B) Slope of the underlying land
Explanation:
The velocity of a glacier depends largely on the steepness of its slope, as steeper slopes cause the glacier to flow faster due to gravity.


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