A glacier is a massive ice mass that travels slowly across land. The word glacier is derived from the French word “glace”, which means ice. Glaciers are commonly referred to as ice rivers. Though a glacier is not liquid, it moves over time due to the constant pressure exerted by the snow that has collected above it which is responsible for the creation of various landforms. The rate of movement is fastest in the center, where there are few obstacles. Glaciation produces erosional and depositional features in the highlands and lowlands, respectively. Its valley is eroded by plucking and abrasion. In this article, we will discuss various Glacial Erosional Landforms which will be helpful for UPSC IAS exam.

Glacial Cycle of Erosion

Youth

• The inward-cutting action of ice in a cirque characterizes this stage.
• Aretes and horns are beginning to appear.
• At this point, the hanging valleys are hardly visible.

Maturity

• The valley glacier transforms into a trunk glacier, resulting in the formation of hanging valleys.
• The opposite cirques get closer, and the glacial valley takes on a regular and graded stepped contour.

Old age

• The beginning of old age is marked by the appearance of a 'U'-shaped valley.
• A conspicuous development is an outwash plain with eskers, kame terraces, drumlins, kettle holes, and other features.
• The summit heights are substantially decreased as the opposing cirques converge.
• The peaks of the mountains become rounded.

Glacier Erosional Landforms

Corrie/ Cirque

• Corries or cirques are deep hollows formed by the erosion of tiny glaciers in the heads of mountain valleys.
• They're often found at the apex of a glacial valley.
• Cirques are formed when the accumulated ice sheets descend down a mountain, cutting the soil.
• When the glacier melts, water fills the cirques, which are subsequently referred to as cirque lakes.
• Tarns and corrie lakes are other names for them.

Glacial Troughs and Ribbon Lakes

• Several corries feed glaciers on their downhill trek, scratching and grinding the bedrock while straightening out any jutting spurs.
• The valley floor is thus deepened, and the interlocking spurs are blunted to form truncated spurs.
• As a result, the glaciated valley takes on the shape of a U, with a wide flat floor and very steep sides.
• The deep areas of these long, narrow glacial troughs may be filled with water after the ice melts, generating Ribbon lakes, also known as Trough lakes or Finger Lakes.

Hanging Valleys

• As it contains considerably larger glaciers, the main valley has been degraded far more than the tributary valley.
• Following the melting of the ice, a subsidiary valley rises above the main valley and cascades down like a waterfall.
• Hanging valleys are the name given to such tributary valleys.
• Hanging valleys may create a natural water head that can be used to generate hydroelectric power.

Aretes

• Arêtes are knife-edged ridges generated when two corries cut back on opposite sides of the mountain.
• A recession forms an angular horn or pyramidal peak when three or more cirque are trimmed back together.

Horn

• Horns are a single pyramidal peak formed when cirque basins on all sides erode the summit.
• Glacial activity cuts into the steep-sided, sharp-tipped peak from two directions.

Fjord

• If the glacier flows all the way down to the sea, it dumps its moraine burden into the water.
• Moraine material will only be dropped when parts break apart as icebergs.
• The bottom end of the trough is drowned by the sea, forming a deep, steep side inlet known as a Fjord, which is common along the Norwegian and Chilean coasts.
• Norway, Greenland, and New Zealand all have fjords.

Types of Glaciers

Continental Glaciers

• Continental glaciers are continuous masses of ice that are much larger than alpine glaciers.
• There are no mountains or other features that surround these glaciers.
• As a result, they tend to spread out and cover everything in their path.
• When ice sheets spread out from the center, they cover entire valleys, plains, and even mountain ranges with snow.
• By definition, they have areas larger than 50,000 km square.
• Some examples of continental glaciers are Antarctica, Iceland, Greenland, etc.

Ice Caps

• The ice caps are the snow and ice covers on mountain ranges that give rise to valley or mountain glaciers.
• These massive glacial formations can feed a variety of different glaciers that branch out from their center.
• They can be found at lower elevations as well.
• The area of the ice caps is less than 50,000 km square.

Piedmont Glaciers

• At the foot of the mountains, the piedmont glaciers form a continuous sheet of ice.
• A mass of ice that has moved downslope towards low-lying plains is referred to as a Piedmont Glacier.
• It spreads out throughout the landscape, forming broad lobes of solid ice.
• One of the most well-known instances of this type of glacier is Alaska's Malaspina Glacier.

Valley Glaciers

• A valley glacier is a glacier that fills a valley. Valley glaciers, also known as Alpine Glaciers, are located in valleys formed by high mountains such as the Himalayas in India.
• Because of their long and narrow, ribbon-like shape, these glaciers are generally simple to spot.
• The majority of valley glaciers originate in mountain glaciers and extend to gorges, basins, and, of course, valleys.

Significance of Glaciers

• Drinking water is provided by glaciers.
• Crops are irrigated by glaciers.
• Glaciers aid in the generation of hydroelectric power.
• They help in shaping the landforms.

Conclusion

Glaciers are incredibly powerful agents of erosion. They have covered more than one-third of the Earth's surface in the past, and they still flow and sculpt features in many locations now. Glaciers begin to form where more snow accumulates each year than they melt. Immediately after it falls, the snow either compresses or becomes denser and begins to crowd.

FAQs

Q1: What is a cirque?

Q2: How does a corrie differ from a cirque?

Q3: What is a glacial trough?

Q4: What characterizes a hanging valley?

Q5: What is an arete?

MCQs

1. What feature is formed at the head of a glacier?

A) Glacial Trough

B) Hanging Valley

C) Cirque

D) Arete

2. Which of the following describes a U-shaped valley?

A) Cirque

B) Arete

C) Glacial Trough

D) Horn

3. What distinguishes a hanging valley from a regular valley?

A) It is deeper than the main valley.

B) It is completely flat.

C) It is elevated above the main valley.

D) It has a circular shape.

4. Which glacial feature forms between two valleys due to erosion?

A) Horn

B) Corrie

C) Arete

D) Fjord

5. What is a horn in glacial geography?

A) A depression formed by a glacier.

B) A peak that forms where three or more glaciers meet.

C) A flat area left after glacial retreat.

D) A type of fjord.

GS Mains Questions and Model Answers

Q1. Explain the processes that lead to the formation of glacial landforms such as cirques and horns.

Answer: Glacial landforms such as cirques and horns are formed through various processes of glacial erosion. A cirque forms at the head of a glacier, where the accumulation of snow transforms into ice. The weight of the ice leads to the process of plucking, where the glacier pulls away chunks of bedrock, deepening the depression. This is often accompanied by abrasion, where the movement of the glacier smooths and scours the rock surface. As the glacier advances, it shapes the surrounding landscape. In contrast, a horn forms when three or more glaciers erode a peak from different sides, creating a sharp, steep summit. The continual movement and melting of glacial ice contribute to the distinctive features of these landforms, highlighting the dynamic interplay between ice and geology in shaping the Earth's surface.

Q2. Discuss the environmental significance of glacial landforms in the context of climate change.

Answer: Glacial landforms such as cirques, troughs, and fjords serve as critical indicators of climate change. These features reflect past glacial activity, and their current state provides insights into the ongoing impacts of global warming. As temperatures rise, glaciers retreat, leading to the alteration of these landforms and the ecosystems they support. The melting of glaciers contributes to rising sea levels, which can inundate coastal areas, and alters freshwater availability in regions dependent on glacial meltwater. Additionally, the retreat of glaciers reveals underlying landscapes, affecting local habitats and biodiversity. Understanding the dynamics of glacial landforms is essential for predicting future environmental changes and developing adaptive strategies to mitigate the impacts of climate change on ecosystems and human communities.

Q3. Evaluate the role of glacial erosion in shaping the topography of mountainous regions.

Answer: Glacial erosion plays a pivotal role in shaping the topography of mountainous regions. As glaciers advance, they carve U-shaped valleys, fjords, and sharp ridges, fundamentally transforming the landscape. The immense weight of glacial ice leads to the erosion of underlying rock through processes such as plucking and abrasion. This not only deepens valleys but also creates unique features like cirques, horns, and aretes that define the rugged beauty of mountainous terrains. The glacial processes contribute to the development of a diverse range of landforms that influence local ecosystems, hydrology, and climate. Moreover, the historical evidence of glacial erosion aids in understanding the geological history and climatic shifts of an area, making glacial landforms critical to the study of Earth's topography and environmental changes.

Previous Year Questions on  Glacial Erosional Landforms

1. UPSC CSE 2020

Question. Discuss the formation and significance of glacial landforms in the context of physical geography.

Answer: Glacial landforms, including cirques, troughs, and fjords, are significant in physical geography as they illustrate the processes of glacial erosion and deposition. The formation of these landforms results from the action of moving ice that sculpts the landscape through mechanisms such as abrasion and plucking. For instance, cirques are formed at the heads of glaciers, where they erode the landscape into bowl-shaped depressions. Glacial troughs emerge as glaciers carve U-shaped valleys, while fjords are created when glaciers retreat, allowing seawater to fill the valleys. The significance of these landforms extends beyond aesthetics; they provide insights into past climatic conditions and serve as indicators of ongoing environmental changes due to climate variations. Understanding these processes and their implications is essential for comprehending the dynamic interactions between climate, geology, and ecology.

2. UPSC CSE 2019

Question. Evaluate the impact of glacial erosion on the environment and human activities.

Answer: Glacial erosion significantly impacts the environment and human activities, shaping landscapes and influencing ecosystems. The erosion caused by glaciers results in the creation of distinct landforms such as valleys, lakes, and moraines, which can affect local climates and biodiversity. For human activities, glacial landscapes can provide resources like freshwater and minerals but also pose challenges, such as natural hazards associated with glacier retreat, including increased flooding and landslides. The melting of glaciers contributes to rising sea levels, threatening coastal communities and ecosystems. Moreover, the changing landscapes require adaptations in agriculture, tourism, and water management. Understanding the effects of glacial erosion is vital for developing sustainable strategies to mitigate its impact on both the environment and human populations.