ACTION OF WAVES

WEEK 6

SUBJECT:GEOGRAPHY

CLASS:    SS 2   

DATE: ………………………………..

TOPIC:                  ACTION OF WAVES

CONTENT:

1. Definition of Waves, Tides and Ocean Currents and their Characteristics. 2. Erosional Processes of Waves
2. Erosional Features of Wave Action 4. Features of Coastal Deposition

SUB-TOPIC 1: DEFINITION OF WAVES, TIDES AND OCEAN CURRENTS

Waves are formed by winds blowing over the ocean surface which cause the surface water to move towards the coast in ripples or waves. In other word wave can be defined as an oscillatory movement of a large body of water approaching the coast. It is the most powerful and important agent of marine erosion.

Tide is the alternate rise and fall of the surface of the sea, approximately two times a day.

Ocean current is the regular movement of the surface water of the ocean from one part of the ocean to another.

SUB – TOPIC 2: EROSIONAL PROCESSES OF WAVES (MECHANISM OF WAVE EROSION) 1. Corrosion: It is the wearing down of the base of the cliff by mass of fragments carried by wave action. 2. Attrition: It is the breaking down of materials like pebbles, boulders, etc. when they hit cliff faces and each other, as the wave continues its activities, into smaller particles. This results in relatively fine pieces of fragments which are well polished.

3. Solution/Solvent action: It involves the disintegration of rock materials such as limestone and chalk in the coast by chemical action of the sea.
4. Hydraulic action: In this process, fast moving waves force themselves into cracks and cavities within the base of the cliff under pressure and enlarge the cracks.

SUB – TOPIC 3: EROSIONAL FEATURES OF WAVE ACTION

The features produce by wave action include:

(a) Cape: – A cape is a prominent projection, headland or cliff protruding into the sea. Capes are made up of hard rock and are usually resistant to wave actions. Examples of cape in West Africa are Cape Three Points in Ghana, Cape Verde in Senegal etc.

(b) Bay: – A bay is a wide curved inlet of sea or a wide opening carrying indentation of the sea or lake into the land. Bays are less steep than capes, they are inlets made up of relatively soft rocks, bays usually contain water and they are used as harbour.

Cape and bay

(c) Cliff: A cliff is a steep rock faces adjoining the coast and usually following the collapse of the part of the rock overlying a notch. Some cliffs are vertical while others are inclined depending on the structure and resistance of the coastal rocks.

Cliff

(d) Caves: A cave is a hole produced in the regions of local weakness at the base of a cliff. The feature is often formed by wave action when the softer rocks are more quickly eroded than the harder rocks. It is characterised by round nature or cylindrical shape, the inside slopes are steep-sided.

(e) Stack: A stack is a steep pillar of rock which results from the collapse of an arch by wave action rising from the sea. A stack was formerly part of the mainland but has become isolated by wave action. The pillar of rock left behind by wave action is known as STACK

(f) Stump: A stump is the eroded remains of a rock pillar which is only just visible above the sea level. A stump is shorter than a pillar, it has fairly steep sides.

Cave, stack and stump EVALUATION:

1. Define the term waves
2. State four erosional features of wave action. 3. Describe two of the above features.

SUB-TOPIC 4: FEATURES OF COASTAL DEPOSITION

Depositional Landforms Resulting from wave transportation include:(i)Beaches(ii)Spits(iii)Bars    (iv) Marine dunes and belts

1. Beaches: They are made up of sand and gravel. They are depositional features on the coastal. Beaches are formed when sand and gravel loosened from the land are moved by waves to be deposited along the shore.
2. A Spit is a tongue like features made up of aluminium deposit that extends from the land to the sea. They are characterised by long and narrow ridges. An example is the Senegal estuary in West Africa.
3. Bar: This is a bank of mud, sand and shingle deposited in water offshore parallel to the coast. It may be deposited across the mouth of the river or across the exit to a harbour.
4. Marine dune and belts: These are dunes or sand dune belts which result from the force of onshore winds. They are carried landwards by these winds and deposited where they occur.

EVALUATION:

1. List and explain four features of coastal deposition.

GENERAL EVALUATION

1. Write an explanatory notes on the following features (i) Beaches

(ii) Capes and bays (iii) Cliff

1. With the aid of annotated diagrams describe the formation and appearance of the following: (i) Stack

(ii) Cave

WEEKEND ASSIGNMENT

Objective Test

1. When the roof of a natural arch collapses, the resulting rock pillar left standing in the sea is called (A) headland. (B) stack. (C) tombolo. (D) wave-cut platform.
2. Which of the following features is formed by marine erosion? (A) Stack (B) Rift valley (C) Spit (D) Hanging valley.
3. Which of these features is associated with wave (a) action (b) bay (c) barchans (c) bush (d) dunes? 4. Which of the following is not a feature of wave deposition (a) barchans (b) bay (c) spit (d) cliff
4. Spits are formed by (A) ocean currents and trade winds (B) wave erosion (C) long share drift and wave deposition (D) westerly winds.

ESSAY QUESTION

1. Describe the mechanism of wave erosion.

READING ASSIGNMENT:

Read about climatic factors.

SUMMARY

Waves are a fundamental part of our world, affecting everything from the weather and the environment to energy and information transfer.

There are many different kinds of waves, each with unique characteristics that affect how they behave.

Some important differences between transverse and longitudinal waves include their speed, amplitude, and direction.

Amplitude refers to the height of a wave, and it determines how much energy is transferred during each oscillation. For example, a high amplitude wave will carry more energy than a low amplitude wave, allowing it to travel farther or penetrate deeper into materials like solids and liquids.

To generate a standing wave, you can use interference to combine two waves at different frequencies. This creates standing waves with distinct patterns of maximum and minimum amplitudes, which can be used to measure things like the wavelengths or frequencies of different waves.

The three primary properties of waves are wavelength, frequency, and wave speed. These properties determine how a wave behaves, including its ability to carry energy or information. For example, sound waves typically have a lower frequency and wavelength than light waves, which allows them to travel further through air but not as far through solids or liquids.

Some properties of electromagnetic radiation, such as x-rays and ultraviolet rays, include the ability to penetrate materials due to their high frequencies and wavelengths. Electromagnetic radiation also has unique wave properties, such as the ability to be refracted and diffracted by different materials.

Because waves are a fundamental aspect of our world and affect nearly everything we do, it is important to have a solid understanding of how they work.

By better understanding wave properties like frequency, wavelength, and amplitude, we can use this knowledge to develop new technologies and improve our understanding of the world around us.

Evaluation

1. What is the difference between a transverse and a longitudinal wave?

2. How does an amplitude affect a wave?

3. How can you generate a standing wave?

4. What are the three primary properties of waves?

5. What do waves carry energy or information?

6. How do sound and light waves differ from other kinds of waves?

7. What is the relationship between frequency, wavelength, and wave speed?

8. What are some properties of electromagnetic radiation, such as x-rays and ultraviolet rays?

9. Why is it important to understand how waves work in our world?

REFERENCES TEXTS

1. Certificate Physical and Human Geography for Senior Secondary Schools (New Impression) by O. Areola, K. Ahmed, O.I. Irueghe, B.O Adeleke and G.C. Leong
2. Comprehensive Geography for Senior Secondary Schools (New Edition) by P. Oluwafemi, and S. Ajayi
3. Essential Geography for Senior Secondary Schools by O. A. Iwena