Geomorphic Processes Notes

This chapter explains the geomorphic forces responsible for continuous modification of Earth’s surface. It highlights the role of internal and external forces, weathering, mass movements, erosion, deposition and soil-forming processes. (NCERT Pages 37–46)

Major Topics Covered

• Geomorphic processes
• Endogenic and exogenic forces
• Diastrophism
• Volcanism
• Weathering
• Chemical weathering
• Physical weathering
• Biological weathering
• Mass movements
• Landslides
• Erosion and deposition
• Soil formation
• Soil-forming factors

Geomorphic processes are physical and chemical actions that modify Earth’s surface.

Causes of Geomorphic Processes

• Endogenic forces
• Exogenic forces

Types of Geomorphic Processes

Endogenic Forces

• Originate inside the Earth.
• Responsible for:
  • Mountain building
  • Upliftment
  • Volcanism
  • Earthquakes
• Known as land-building forces.

Exogenic Forces

• Originate from atmosphere.
• Powered mainly by solar energy.
• Responsible for wearing down relief.
• Fill depressions through deposition.

• Gravity activates downslope movement.
• Responsible for:
  • Erosion
  • Transportation
  • Deposition

Main Sources of Energy

• Radioactivity
• Primordial heat
• Rotational friction
• Tidal friction

Major Endogenic Processes

Important Facts

• Orogeny forms mountains.
• Epeirogeny forms continents.
• Faulting and folding occur due to tectonic activity.

• Movement of magma toward Earth’s surface.
• Produces:
  • Intrusive landforms
  • Extrusive landforms

Exogenic processes derive energy mainly from the Sun and are controlled by climate, gravity and slope.

Main Exogenic Processes

Meaning of Weathering

• Mechanical disintegration and chemical decomposition of rocks.
• It is an in-situ process.
• No major transportation involved.

Types of Weathering

Causes

• Temperature changes
• Crystal growth
• Pressure release
• Wetting and drying

Important Feature

• Rocks break without chemical change.

Agents

• Plant roots
• Earthworms
• Rodents
• Termites
• Human activities

Effects

• Rock breaking
• Soil formation
• Humus development

Mass movements are downslope movements caused by gravity.

Main Types

Causes of Landslides

• Steep slopes
• Heavy rainfall
• Earthquakes
• Removal of vegetation
• Overloading

Types of Landslides

Important Fact

• Himalayas are highly prone to landslides.

Erosion

• Removal and transportation of weathered materials.

Agents of Erosion

• Running water
• Wind
• Glaciers
• Waves
• Groundwater

Deposition

• Settling of transported materials.
• Occurs when transporting agents lose energy.

Soil

• Dynamic natural body.
• Contains:
  • Mineral matter
  • Organic matter
  • Water
  • Air

Pedogenesis

• Process of soil formation.

Very Short Answer Questions

1. What are geomorphic processes? (NCERT Page 37)
2. Define gradation. (NCERT Page 37)
3. What is denudation? (NCERT Page 39)
4. Define weathering. (NCERT Page 40)
5. What is exfoliation? (NCERT Page 41)

Short Answer Questions

1. Differentiate between endogenic and exogenic forces. (NCERT Pages 37–39)
2. Explain geomorphic agents. (NCERT Page 38)
3. Describe types of weathering. (NCERT Pages 40–41)
4. Explain biological weathering. (NCERT Page 41)
5. Describe causes of landslides. (NCERT Pages 42–43)

Long Answer Questions

1. Explain geomorphic processes and their significance. (NCERT Pages 37–39)
2. Discuss physical, chemical and biological weathering. (NCERT Pages 40–41)
3. Explain mass movements and landslides. (NCERT Pages 41–43)
4. Describe the process of soil formation. (NCERT Pages 44–45)

1. What are geomorphic processes?

Processes that shape and modify Earth’s surface are called geomorphic processes. (NCERT Pages 37–38)

2. What is denudation?

Denudation is the stripping and lowering of Earth’s surface through weathering and erosion. (NCERT Page 39)

3. What are the main types of weathering?

Chemical, physical and biological weathering are the three main types. (NCERT Pages 40–41)

4. Why are Himalayas prone to landslides?

Due to steep slopes, tectonic activity and heavy rainfall. (NCERT Pages 42–43)

5. What is pedogenesis?

Pedogenesis is the process of soil formation. (NCERT Page 44)

• Endogenic forces build relief.
• Exogenic forces wear down relief.
• Geomorphic agents include rivers, glaciers and wind.
• Diastrophism includes orogeny and epeirogeny.
• Weathering is an in-situ process.
• Chemical weathering includes carbonation and oxidation.
• Biological weathering supports soil formation.
• Landslides are gravity-induced movements.
• Erosion transports weathered materials.
• Pedogenesis means soil formation.
• Climate is a major soil-forming factor.