Geomorphic Processes

1. Introduction to Geomorphic Processes

• Geomorphic processes are the natural mechanisms that shape the Earth’s surface.
• These processes are driven by endogenic (internal) and exogenic (external) forces.
• The Earth’s surface is constantly changing due to these processes.

2. Endogenic Processes

• Processes originating from within the Earth’s interior.
• Types:
  • Diastrophism: Large-scale deformation of the Earth’s crust.
    • Orogenic Processes: Mountain-building processes.
    • Epeirogenic Processes: Uplift or depression of large land areas.
  • Volcanism: Movement of magma toward or onto the Earth’s surface.
    • Intrusive Volcanism: Magma solidifies below the surface (e.g., batholiths, laccoliths).
    • Extrusive Volcanism: Magma erupts onto the surface (e.g., lava flows, volcanic cones).
  • Earthquakes: Sudden shaking of the Earth’s crust due to tectonic activity.
    • Focus: The point inside the Earth where the earthquake originates.
    • Epicenter: The point on the Earth’s surface directly above the focus.

3. Exogenic Processes

•  Processes originating from outside the Earth’s surface.
• Types:
  • Weathering: Breakdown of rocks in situ.
    • Mechanical Weathering: Physical breakdown (e.g., frost action, thermal expansion).
    • Chemical Weathering: Chemical alteration (e.g., oxidation, hydrolysis, carbonation).
    • Biological Weathering: Breakdown by living organisms (e.g., roots, burrowing animals).
  • Erosion: Removal of weathered material by agents like water, wind, ice, and waves.
  • Mass Movement: Downslope movement of material under gravity.
    • Examples:  Creep, slump, landslide, avalanche.
  • Deposition: Accumulation of eroded material in new locations.

4. Gradation

• The process of leveling the Earth’s surface by erosion and deposition.
• Agents of Gradation:
  • Running Water: Forms valleys, gorges, floodplains, deltas.
  • Glaciers: Create U-shaped valleys, moraines, drumlins.
  • Wind: Forms sand dunes, loess deposits.
  • Waves: Create sea cliffs, beaches, spits.
  • Groundwater: Forms caves, sinkholes, stalactites, stalagmites.

5. Landforms and their Evolution

• Fluvial Landforms: Created by running water (e.g., meanders, oxbow lakes, alluvial fans).
• Arid Landforms: Shaped by wind and water in deserts (e.g., yardangs, zeugens, inselbergs).
• Glacial Landforms: Formed by glacial activity (e.g., cirques, aretes, fjords).
• Coastal Landforms: Shaped by wave action (e.g., sea caves, arches, stacks).
• Karst Landforms: Formed by the dissolution of limestone (e.g., karst valleys, poljes).

6. Soil Formation

•  The process of soil development from the weathering of rocks.
• Factors Influencing Soil Formation:
  • Parent Material: The original rock from which soil is formed.
  • Climate: Temperature and precipitation affect weathering rates.
  • Topography: Slope and elevation influence drainage and erosion.
  • Biological Activity: Plants and animals contribute organic matter.
  • Time: The duration over which soil-forming processes operate.

7. Significance of Geomorphic Processes

• Landform Development: Shapes the Earth’s surface into mountains, valleys, plains, etc.
• Resource Formation: Creates fertile soils, mineral deposits, and groundwater reservoirs.
• Hazard Mitigation: Understanding processes helps in managing natural disasters like earthquakes, landslides, and floods.

8. Human Impact on Geomorphic Processes

• Deforestation: Accelerates soil erosion and alters river courses.
• Urbanization: Increases surface runoff and reduces groundwater recharge.
• Mining: Causes land subsidence and alters landscapes.
• Agriculture: Leads to soil degradation and changes in landforms.

9. Conclusion

• Geomorphic processes are fundamental to understanding the dynamic nature of the Earth’s surface.
• Both endogenic and exogenic processes play crucial roles in shaping the landscape.
• Human activities can significantly alter these natural processes, leading to environmental changes.

MCQ Practice 

1. Consider the following statements regarding geomorphic processes:

1. Geomorphic processes are exclusively driven by external forces acting on the Earth’s surface.
2. Both endogenic and exogenic processes contribute to the continuous change in the Earth’s surface.
3. Volcanism is classified as an exogenic process.

Which of the statements given above is/are correct?
(a) 1 and 3 only
(b) 2 only
(c) 1 and 2 only
(d) 2 and 3 only

Answer: (b) 2 only

Explanation:

• Statement 1 is incorrect because geomorphic processes are driven by both internal (endogenic) and external (exogenic) forces. Endogenic processes like volcanism and earthquakes originate from within the Earth.
• Statement 2 is correct as both endogenic (e.g., earthquakes, volcanism) and exogenic (e.g., weathering, erosion) processes contribute to shaping the Earth’s surface.
• Statement 3 is incorrect because volcanism is an endogenic process, as it originates from within the Earth’s interior.

2. With reference to endogenic processes, consider the following statements:

1. Diastrophism includes both orogenic and epeirogenic movements.
2. Volcanism can be categorized into intrusive and extrusive types.
3. Earthquakes occur only due to volcanic activity.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2, and 3

Answer: (a) 1 and 2 only

Explanation:

• Statement 1 is correct as diastrophism refers to the deformation of the Earth’s crust, which includes orogenic (mountain-building processes) and epeirogenic (uplift and subsidence of land masses) movements.
• Statement 2 is correct because volcanism can be classified into intrusive (magma solidifies below the surface, forming batholiths, laccoliths, etc.) and extrusive (magma erupts onto the surface, forming lava flows and volcanic cones).
• Statement 3 is incorrect because earthquakes occur due to multiple reasons, including tectonic movements along faults, volcanic eruptions, and human activities like mining and reservoir-induced seismicity.

3. Consider the following statements regarding exogenic processes:

1. Exogenic processes include weathering, erosion, mass movement, and deposition.
2. Chemical weathering is more active in hot and arid regions than in humid regions.
3. Biological weathering involves the breakdown of rocks by living organisms.

Which of the statements given above is/are correct?
(a) 1 and 3 only
(b) 1 and 2 only
(c) 2 and 3 only
(c) 2 and 3 only

Answer: (a) 1 and 3 only

Explanation:

• Statement 1 is correct as exogenic processes involve weathering, erosion, mass movement, and deposition, all of which act on the Earth’s surface due to external forces like wind, water, and gravity.
• Statement 2 is incorrect because chemical weathering is more active in humid and warm regions, where water and chemical reactions like oxidation, hydrolysis, and carbonation take place more effectively. In arid regions, mechanical weathering is dominant due to high temperature variations.
• Statement 3 is correct as biological weathering occurs due to the activity of plants (root penetration), animals (burrowing), and microorganisms (organic acid production), which contribute to rock breakdown.

4. Consider the following pairs regarding agents of gradation and the landforms they create:

Agent of Gradation	Landform Created
1. Running Water	Alluvial Fan
2. Glaciers	Inselberg
3. Wind	Loess Deposits
4. Waves	Sea Cliffs

Which of the pairs given above are correctly matched?
(a) 1, 3, and 4 only
(b) 1 and 2 only
(c) 2 and 4 only
(d) 1, 2, 3, and 4

Answer: (a) 1, 3, and 4 only

Explanation:

• Pair 1 is correct: Running water deposits sediments and creates alluvial fans, meanders, and oxbow lakes.
• Pair 2 is incorrect: Glaciers create U-shaped valleys, moraines, drumlins, cirques, and fjords, but not inselbergs, which are formed by wind and water erosion in arid regions.
• Pair 3 is correct: Wind transports and deposits fine silt and dust, forming loess deposits.
• Pair 4 is correct: Waves erode coastal areas, forming sea cliffs, sea caves, arches, and stacks.

5. Which of the following statements regarding soil formation is/are correct?

1. Parent material is the most important factor determining soil characteristics.
2. Biological activity plays no significant role in soil formation.
3. Soil formation is a rapid process and occurs within a few years.

Select the correct answer using the codes given below:
(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2, and 3

Answer: (a) 1 only

Explanation:

• Statement 1 is correct: Parent material (original rock) determines the mineral composition and texture of the soil.
• Statement 2 is incorrect: Biological activity (e.g., decomposition of organic matter, burrowing of animals) greatly influences soil fertility and structure.
• Statement 3 is incorrect: Soil formation is a slow process, often taking hundreds to thousands of years.

6. Consider the following statements regarding the significance of geomorphic processes:

1. They help in the formation of landforms like mountains, plains, and valleys.
2. They contribute to resource formation, including soil, minerals, and groundwater.
3. They have no role in disaster mitigation.

Which of the statements given above is/are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2, and 3

Answer: (a) 1 and 2 only

Explanation:

• Statement 1 is correct: Geomorphic processes shape mountains, valleys, and plains through erosion, deposition, and tectonic activities.
• Statement 2 is correct: Many natural resources like fertile soils, minerals, and groundwater are formed due to geomorphic processes.
• Statement 3 is incorrect: Understanding geomorphic processes helps in hazard mitigation by predicting earthquakes, landslides, and floods.

7. Which of the following human activities can influence geomorphic processes?

1. Deforestation
2. Mining
3. Urbanization
4. Agriculture

Select the correct answer using the codes given below:
(a) 1, 2, and 3 only
(b) 2 and 4 only
(c) 1, 3, and 4 only
(d) 1, 2, 3, and 4

Answer: (d) 1, 2, 3, and 4

Explanation:

• All four activities significantly alter natural geomorphic processes:
  • Deforestation increases soil erosion and alters river courses.
  • Mining leads to land subsidence, soil degradation, and landscape modification.
  • Urbanization reduces groundwater recharge and increases runoff and erosion.
  • Agriculture changes landforms through soil degradation, deforestation, and irrigation.