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Landforms Formed by Fluvial, Aeolian and Glacial Actions (UPSC Geography Notes)
Overview: The Earth’s surface is constantly shaped by various natural agents like rivers, wind, and glaciers. These agents erode, transport, and deposit materials, forming different types of landforms. In this UPSC Geography note, we study fluvial, aeolian, and glacial landforms — how they are formed and their major characteristics.
Table of Contents
- 1. Introduction
- 2. Fluvial Landforms (by Rivers)
- 3. Aeolian Landforms (by Wind)
- 4. Glacial Landforms (by Ice)
- 5. Comparison of the Three Agents
- 6. Importance of Studying Landforms
- 7. UPSC Quick Revision Notes
- 8. Previous Year Question
1. Introduction
The forces that shape the Earth’s surface are called geomorphic agents. They include water, wind, ice, waves, and gravity. Each of these agents creates distinct landforms through the processes of erosion, transportation, and deposition. Understanding these helps us interpret Earth’s physical features and geological history.
2. Fluvial Landforms (by Rivers)
Rivers are the most powerful agents of erosion and deposition. The landforms they create depend on the stage of the river — upper course (erosional), middle course (transportational), and lower course (depositional).
(a) Erosional Landforms
- V-shaped Valleys: Narrow valleys formed by vertical erosion in youthful stage.
- Gorges and Canyons: Deep, steep-sided valleys created by river down-cutting (e.g., Grand Canyon, USA).
- Waterfalls: Sudden drops in the river course due to resistant rock layers (e.g., Jog Falls, India).
- Rapids: Irregular river flow over uneven rocks creating turbulence.
(b) Depositional Landforms
- Alluvial Fans: Formed when rivers lose velocity and deposit sediments at foothills.
- Floodplains: Flat fertile areas formed by river floods depositing fine silt.
- Meanders: Loops and bends formed in the middle course due to lateral erosion and deposition.
- Oxbow Lakes: Cut-off meander loops forming crescent-shaped lakes.
- Deltas: Triangular deposits formed where rivers meet the sea (e.g., Ganga-Brahmaputra Delta).
3. Aeolian Landforms (by Wind)
Wind acts as a dominant geomorphic agent in arid and semi-arid regions. It shapes the landscape through erosion, transportation, and deposition of sand and dust.
(a) Erosional Landforms
- Deflation Hollows: Depressions formed by removal of loose particles by wind.
- Mushroom Rocks: Rocks shaped like mushrooms due to wind abrasion near the base.
- Yardangs: Long ridges carved by persistent winds in desert surfaces.
- Zeugen: Table-like landforms formed by differential erosion of rock layers.
(b) Depositional Landforms
- Sand Dunes: Mounds of sand formed by wind deposition; types include barchans, seifs, and parabolic dunes.
- Loess: Fine dust deposited over large areas, forming fertile soils (e.g., China’s Loess Plateau).
- Sand Sheets: Extensive flat sand-covered areas with minimal dune development.
4. Glacial Landforms (by Ice)
In cold regions, glaciers act as powerful agents of erosion and deposition. Moving ice erodes the land beneath and deposits debris known as moraine.
(a) Erosional Landforms
- Cirques (Corries): Bowl-shaped hollows at mountain heads where glaciers originate.
- Arêtes: Sharp ridges between two cirques.
- U-shaped Valleys: Broad valleys formed by glacier movement (contrast to V-shaped river valleys).
- Hanging Valleys: Smaller valleys that join main valleys at a higher level, often forming waterfalls.
- Roche Moutonnée: Asymmetrical rock hill shaped by glacier abrasion and plucking.
(b) Depositional Landforms
- Moraines: Accumulations of glacial debris (lateral, medial, terminal, and ground moraines).
- Drumlins: Smooth, elongated hills formed beneath moving ice.
- Eskers: Long, winding ridges formed by meltwater streams flowing beneath glaciers.
- Outwash Plains: Flat areas formed by glacial meltwater deposition beyond the ice front.
5. Comparison of the Three Agents
| Agent | Major Process | Dominant Regions | Common Landforms |
|---|---|---|---|
| Fluvial (River) | Erosion & Deposition by running water | Humid & Temperate regions | Valleys, Floodplains, Deltas |
| Aeolian (Wind) | Erosion, Transportation & Deposition by wind | Deserts & Semi-arid areas | Dunes, Loess, Yardangs |
| Glacial (Ice) | Plucking & Abrasion by moving ice | Polar & Mountain regions | U-shaped Valleys, Moraines, Cirques |
6. Importance of Studying Landforms
- Helps in understanding Earth’s evolution and geomorphic history.
- Aids in disaster management like floods and landslides.
- Useful in planning infrastructure (roads, dams, settlements).
- Assists in soil and resource management for agriculture and mining.
7. UPSC Quick Revision Notes
Aeolian Landforms: Wind – dunes, loess, mushroom rocks.
Glacial Landforms: Ice – cirques, moraines, U-shaped valleys.
All three agents involve erosion, transportation, and deposition.
Regions differ: humid (fluvial), arid (aeolian), cold (glacial).
8. Previous Year Question
Q. Which one of the following landforms is produced by both erosion and deposition of a river?
(a) Delta
(b) Meander
(c) Waterfall
(d) Alluvial Fan
Answer: (b) Meander
Related Keywords
Fluvial Landforms UPSC Notes, Aeolian Landforms, Glacial Landforms, Geomorphic Processes, Landform Development, Physical Geography NCERT Notes, UPSC Geography.
Sources: NCERT – Fundamentals of Physical Geography, Goh Cheng Leong’s Certificate Physical and Human Geography, Geological Survey of India.
