Lesson Notes By Weeks and Term - Senior Secondary 2

TERM – 1^ST TERM

WEEK FOUR

Class: Senior Secondary School 2

Age: 16 years

Duration: 40 minutes of 5 periods each

Date:

Subject: Geography

Topic: ACTION OF WAVES

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

1. Mention concepts that are associated with coastland.
2. Explain the processes of wave erosion.
3. Outline the characteristics of features of coastal erosion and deposition.
4. Analyse the impacts of waves action on man and coastland.

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,

demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

ACTION OF THE WAVES

The action of waves refers to the dynamic processes and effects exerted by waves on coastlines, shores, and landforms along bodies of water. These processes play a fundamental role in shaping coastal environments and influencing the geological features of coastal areas.

Concepts Associated with Coastlands

Several terms are associated with coastal land, describing various features, processes, and ecological components. Here are some key terms:

1. Shoreline: The boundary area where land and water meet, encompassing the dynamic interface between the sea and the land.
2. Beach: A sloping shoreline covered with sand, gravel, or pebbles. Beaches are dynamic environments shaped by waves, tides, and currents.
3. Headland: A high, prominent coastal land formation extending into the sea, often characterized by steep cliffs.
4. Bay: A body of water partially enclosed by land, typically having a wide mouth opening to the sea.
5. Estuary: The area where a river meets the sea, characterized by brackish water and influenced by tidal activity.
6. Delta: A landform created by the deposition of sediment carried by a river as it enters a slower-moving body of water, often the sea.
7. Sand Dune: A hill or ridge of sand, often found along coastlines and shaped by wind and vegetation.
8. Lagoon: A shallow body of water separated from a larger body of water by sandbars, coral reefs, or barrier islands.

Processes of Wave Erosion

1. Hydraulic Action: Waves exert pressure on coastal rocks, forcing air into cracks. The compressed air weakens the rock, leading to erosion.
2. Abrasion: The wearing away of coastal rocks by the impact of waves carrying sand, pebbles, and other particles. This process acts like natural sandpaper.
3. Attrition: The process where particles carried by waves collide with each other, causing them to break into smaller, smoother fragments.
4. Corrosion (Solution): Dissolving of minerals in rocks by acidic seawater. This is particularly effective on carbonate rocks like limestone.
5. Wave Refraction: Bending of waves as they approach the shoreline. This concentrates wave energy on headlands, contributing to localized erosion.

Characteristics of Coastal Erosion Features

1. Sea Cliffs: The erosion by waves undermines the base of cliffs, leading to their vertical appearance having a steep, towering rock faces along the coastline.
2. Sea Caves: Erosion, often in weaker rock layers, creates cave-like structures. With hollow openings in coastal cliffs or headlands.
3. Sea Arches: Continued erosion widens openings in coastal rock, creating arch-shaped features. These are natural archways formed by the erosion of a headland.
4. Stacks and Stumps: Stacks form when the top of an arch collapses, while stumps are remnants of eroded stacks.
5. Wave-Cut Platforms: These are flat, rocky surfaces at the base of cliffs. Formed as result of eosion by waves which creates a flat platform, often exposed during low tide.

Coastal Deposition Features:

1. Beaches: formed from sediment deposited by waves and currents creates sandy or pebbly shores.
2. Spits: The sediment carried by longshore drift accumulates and forms a spit. It is narrow, elongated landforms extending into the sea.
3. Bars: These are sediment deposition by waves, often parallel to the shoreline.
4. Barrier Islands: Result from the deposition of sand and sediment by waves and currents. There are long, narrow islands parallel to the coastline.
5. Tombolos: formed from sediment accumulation by waves and currents forms a bridge-like structure. It is depositional landforms connecting an island to the mainland.
6. Deltas: Sediment carried by rivers is deposited as the water slows upon entering the sea. It is triangular landforms at the mouths of rivers.

Impacts of waves action on man and coastland

Wave action can have both positive and negative impacts on both humans and coastlines. Positively, waves contribute to the natural processes of coastal erosion and sediment transport, shaping landscapes and creating diverse ecosystems. However, excessive wave action can lead to erosion and pose threats to coastal communities and infrastructure.

Negative impacts on humans include the risk of coastal flooding and damage to property due to storm surges and high waves. Additionally, erosion caused by waves can lead to loss of land and displacement of communities.

Coastal ecosystems may also be affected negatively, with waves contributing to the erosion of beaches and dunes. This can disrupt habitats for plants and animals, impacting biodiversity.

To mitigate these impacts, coastal management strategies such as seawalls, beach nourishment, and vegetation planting are employed to balance the natural processes with human needs.

EVALUATION: 1. What is wave action?

2. Discuss 5 processes of wave erosion.
3. Identify 5 characteristics of coastal erosion features.
4. Discuss the positive and negative impacts of wave action to Man and coastland.

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively