Denudational Processes SS3 Geography Lesson Note

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

1. Explain denudation and the factors affecting it
2. Identify denudational processes
3. Explain the sequences of denudation
4. Appraise the impacts of denudation on man and his environment.

INSTRUCTIONAL TECHNIQUES: 

• Identification, 
• explanation, 
• questions and answers,
• demonstration, 
• videos from the source

INSTRUCTIONAL MATERIALS: 

• Videos, 
• loudspeaker, 
• textbook, 
• pictures

NOTE

DENUDATION PROCESSES

Denudation refers to the overall process of wearing down and stripping away the Earth’s surface through various natural agents.

Factors that influence denudation include Weathering, erosion, mass wasting, and human Activities:

Factors Affecting Denudation:

1. Climate: Regions with high rainfall and temperature variations often experience increased denudation due to more intense weathering and erosion.
2. Geology: The type of rocks present influences the susceptibility to weathering and erosion. Soft rocks may erode more quickly than resistant ones.
3. Topography: Steep slopes are more prone to erosion and mass wasting, intensifying denudation.
4. Vegetation: Plants can protect the soil from erosion by stabilising it with roots, so deforestation can accelerate denudation.
5. Human Activities: Urbanisation, agriculture, and industrial processes can contribute significantly to denudation.

Denudational Processes

1. Weathering: Breakdown of rocks into smaller particles by physical (e.g., frost action), chemical (e.g., acid rain), or biological (e.g., plant roots) processes.
2. Erosion: Transport of weathered material by agents such as water (fluvial erosion), wind (aeolian erosion), ice (glacial erosion), or gravity (mass wasting).
3. Mass Wasting: Downward movement of rock and soil under the influence of gravity, including processes like landslides, rockfalls, and slumps.
4. Corrasion (Abrasion): The mechanical wearing away of rocks by particles carried by wind, water, or ice.
5. Attrition: The wearing down of rocks as they collide with each other during transportation by water, wind, or ice.
6. Hydraulic Action: Erosion caused by the force of moving water on rock surfaces.

Sequences of Denudation

The following are sequences for Denudation;

1. Weathering: The initial stage involves the breakdown of rocks into smaller particles through physical, chemical, or biological processes. This prepares the material for transportation.
2. Erosion: The transportation of weathered material by various agents like water, wind, ice, or gravity. Erosion contributes to the removal of loosened material from its original location.
3. Transportation: The movement of eroded material from its source to a new location. This can occur through rivers, glaciers, wind, or gravity.
4. Deposition: Once the transporting agents lose their energy, they deposit the sediment. Deposition results in the accumulation of material in new locations, forming landforms like river deltas, alluvial plains, or glacial moraines.

Impacts of Denudation on Man and His Environment

1. Denudation processes shape the Earth’s surface, creating diverse landforms. However, this can impact human activities, infrastructure, and settlement patterns.
2. Excessive denudation can lead to soil erosion, reducing fertility and affecting agriculture. This has direct implications for food production and livelihoods.
3. Denudation influences river channels and watercourses, impacting water availability, quality, and the potential for flooding or drought in certain regions.
4. Increased denudation can contribute to the occurrence of natural hazards such as landslides, mudslides, and rockfalls, posing risks to human settlements.
5. Habitat destruction due to denudation can lead to the loss of plant and animal species. This impacts ecosystems and reduces biodiversity.
6. Changes in landforms through denudation can affect local climate patterns, including temperature and precipitation regimes.
7. Denudation can expose or bury cultural and archaeological sites, affecting our understanding of human history.
8. Sedimentation from denudation processes can degrade water quality, affecting aquatic ecosystems and human water supply.

EVALUATION: 

1. What is Denudation?

1. Mention 5 factors affecting Denudation.
2. Describe the sequences of Denudation.
3. Mention 5 impacts of Denudation on man and his Environment.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively