Geomorphic Processes for UPSC Prelims
1. Introduction to Geomorphic Processes
Geomorphic processes are natural mechanisms that shape Earth’s surface, driven by internal (endogenic) and external (exogenic) forces. These processes include weathering, erosion, deposition, and mass wasting, which create and modify landforms such as mountains, valleys, and plains. Understanding these processes is essential for UPSC Prelims, as they explain the evolution of Earth’s topography and influence human activities like agriculture and settlement.
Key Facts
- Main Processes: Weathering, erosion, deposition, mass wasting
- Driving Forces: Endogenic (tectonic, volcanic) and exogenic (wind, water, ice)
- Agents: Running water, glaciers, wind, waves, gravity
- Significance: Shapes landforms, impacts ecosystems, and human activities
Important Facts for UPSC
- Geomorphic processes operate over varying timescales, from seconds (landslides) to millennia (mountain erosion).
- India’s diverse landforms (Himalayas, Gangetic plains, Deccan Plateau) result from these processes.
- Weathering and erosion are critical for soil formation and nutrient cycling.
2. Types of Geomorphic Processes
Geomorphic processes are classified based on their origin and action:
| Type |
Description |
Examples |
| Endogenic |
Driven by Earth’s internal energy (tectonic, volcanic) |
Earthquakes, volcanism, mountain building |
| Exogenic |
Driven by external forces (solar energy, gravity) |
Weathering, erosion, deposition |
Exogenic processes dominate surface shaping, while endogenic processes create the initial relief.
Important Facts for UPSC
- Endogenic processes form primary landforms (e.g., Himalayas), which exogenic processes modify.
- Exogenic processes are powered by solar energy via the hydrological cycle.
- Balance between endogenic and exogenic forces shapes Earth’s dynamic surface.
3. Weathering
Overview
Weathering is the in-situ breakdown of rocks into smaller fragments or chemical compounds without significant movement, preparing material for erosion.
Types
- Physical (Mechanical) Weathering: Breaks rocks into smaller pieces without chemical change.
- Frost action: Water freezes in cracks, expanding rocks.
- Thermal expansion: Temperature changes cause rock expansion/contraction.
- Exfoliation: Outer rock layers peel due to pressure release.
- Chemical Weathering: Alters rock composition through chemical reactions.
- Oxidation: Iron in rocks reacts with oxygen, forming rust.
- Hydrolysis: Water reacts with minerals, e.g., feldspar to clay.
- Carbonation: Carbonic acid dissolves limestone, forming caves.
- Biological Weathering: Organisms (plants, animals) break rocks, e.g., tree roots splitting rocks.
Factors
Climate (temperature, rainfall), rock type, topography, and time influence weathering rates.
Important Facts for UPSC
- Chemical weathering dominates in humid tropics (e.g., Western Ghats).
- Physical weathering is prominent in arid (Thar Desert) and cold regions (Himalayas).
- Weathering produces regolith, the basis for soil formation.
4. Erosion
Overview
Erosion is the removal and transportation of weathered material by natural agents like water, wind, ice, or gravity, sculpting Earth’s surface.
Processes
- Hydraulic Action: Water dislodges particles in rivers or waves.
- Abrasion: Particles carried by water, wind, or ice grind rocks.
- Attrition: Transported particles collide, reducing size.
- Solution: Dissolved minerals are carried away (e.g., limestone in water).
Agents
Running water, glaciers, wind, and waves are primary erosional agents, each dominant in specific environments.
Important Facts for UPSC
- River erosion shapes V-shaped valleys (e.g., Ganga in Himalayas).
- Wind erosion creates desert features like yardangs in Rajasthan.
- Glacial erosion forms U-shaped valleys in Kashmir Himalayas.
5. Deposition
Overview
Deposition occurs when erosional agents lose energy, depositing transported materials like sediments, forming new landforms.
Processes
- Sedimentation: Particles settle in layers (e.g., river deltas).
- Aggradation: Build-up of sediments raises land (e.g., floodplains).
- Precipitation: Dissolved minerals solidify (e.g., stalactites in caves).
Agents
Rivers, glaciers, wind, and waves deposit materials in specific environments, e.g., deltas, moraines, dunes.
Important Facts for UPSC
- The Ganga-Brahmaputra Delta is one of the world’s largest depositional landforms.
- Glacial moraines are depositional features in the Himalayas.
- Wind-deposited loess soils are fertile, found in parts of North India.
6. Mass Wasting
Overview
Mass wasting is the downslope movement of rock, soil, or debris under gravity, often triggered by water, earthquakes, or human activity.
Types
- Landslides: Rapid movement of large rock/soil masses (e.g., Himalayan slopes).
- Rockfalls: Free-falling rocks from cliffs.
- Mudflows: Water-saturated debris flows (e.g., during monsoons).
- Creep: Slow, gradual soil movement, often imperceptible.
Factors
Steep slopes, heavy rainfall, earthquakes, and deforestation increase mass wasting risks.
Important Facts for UPSC
- Landslides are frequent in Uttarakhand during monsoons (e.g., 2013 Kedarnath disaster).
- Soil creep creates terraced slopes in hilly regions.
- Mass wasting contributes to river sediment loads, affecting deltas.
7. Agents of Geomorphic Processes
| Agent |
Erosion |
Deposition |
Landforms |
| Running Water |
Cuts valleys, gorges |
Forms deltas, floodplains |
Meanders, oxbow lakes |
| Glaciers |
Carves U-shaped valleys |
Forms moraines, drumlins |
Fjords, cirques |
| Wind |
Creates yardangs, deflation hollows |
Forms dunes, loess |
Mushroom rocks |
| Waves |
Erodes cliffs, sea caves |
Forms beaches, spits |
Stacks, arches |
| Gravity |
Triggers landslides, rockfalls |
Deposits talus slopes |
Scree, debris cones |
Important Facts for UPSC
- Rivers are the most dominant geomorphic agent globally, shaping 70% of landforms.
- Glaciers dominate in high-altitude regions like the Himalayas.
- Wind is significant in arid regions like the Thar Desert.
Fluvial Landforms
Rivers create V-shaped valleys, waterfalls, deltas, and floodplains (e.g., Ganga Plains).
Glacial Landforms
Glaciers form cirques, arêtes, moraines, and U-shaped valleys (e.g., Gangotri Glacier).
Aeolian Landforms
Wind creates dunes, loess deposits, and mushroom rocks (e.g., Rajasthan deserts).
Coastal Landforms
Waves form beaches, cliffs, and spits (e.g., Marina Beach, Chennai).
Karst Landforms
Chemical weathering of limestone creates caves, sinkholes, and stalactites (e.g., Meghalaya caves).
Important Facts for UPSC
- The Brahmaputra’s braided channels are a fluvial landform feature.
- India’s coastal landforms include lagoons like Chilika Lake.
- Karst topography is prominent in Chhattisgarh and Meghalaya.
9. Geomorphic Processes in India
Overview
India’s diverse geography, from the Himalayas to coastal plains, showcases active geomorphic processes influenced by its tectonic setting and monsoon climate.
Key Processes
- Weathering: Chemical weathering in humid Western Ghats; physical in arid Rajasthan.
- Erosion: River erosion in Himalayan rivers (Ganga, Brahmaputra); coastal erosion along eastern coast.
- Deposition: Ganga-Brahmaputra Delta, alluvial plains in North India.
- Mass Wasting: Landslides in Himalayas, e.g., Himachal Pradesh, Uttarakhand.
Examples
- Himalayan erosion forms deep gorges (e.g., Kali Gandaki).
- Monsoon-driven fluvial deposition creates fertile Indo-Gangetic Plains.
- Coastal erosion threatens areas like Odisha’s Konark coast.
Important Facts for UPSC
- India’s Himalayan rivers carry high sediment loads due to intense erosion.
- The Thar Desert’s dunes are shaped by aeolian processes.
- Landslides disrupt infrastructure in Northeast India during monsoons.
10. Significance for Geography
Geological Significance
Geomorphic processes shape Earth’s surface, creating diverse landforms that influence climate, drainage, and ecosystems.
Environmental Significance
Weathering and deposition support soil formation, while erosion and mass wasting pose environmental hazards like floods and landslides.
Socioeconomic Significance
Landforms created by these processes support agriculture (e.g., alluvial plains), mineral extraction, and tourism, but hazards require disaster management.
UPSC Relevance
Geomorphic processes are foundational for physical geography, disaster management, and Indian geography, frequently tested in Prelims.
Important Facts for UPSC
- Geomorphic processes explain India’s fertile plains and rugged terrains.
- Erosion and deposition impact river navigation and irrigation (e.g., Brahmaputra).
- India’s NDMA addresses landslide and flood risks from geomorphic hazards.
UPSC Preparation Tips
- Memorize types of weathering (physical, chemical, biological) and their environments.
- Understand erosion and deposition processes for each agent (water, wind, ice).
- Focus on landforms created by fluvial, glacial, aeolian, and coastal processes.
- Link geomorphic processes to India’s geography (Himalayas, plains, deserts).
- Practice diagram-based questions on landform formation (e.g., delta, dune).
- Revise key terms (exfoliation, abrasion, moraine, karst) and examples.