CoastsAgents shaping Coasts

Coastal processes

Coastal protection measures

1. Waves2. Tides3. Currents

Erosion Transportation Deposition

Forms

Forms

Forms

1. Cliffs & Wave cut platforms 2. Headlands & Bays

Spits BeachesSpitsTombolos

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Definitions• Cliffs

• A steep rock face along a coast. Can tilt forwards or backwards.

• Wave cut platform/ shore platform

• A gentle sloping platform found at the base of the cliff

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1. Waves erodes a coast by hydraulic action and

abrasion

2. Erosion process attacks lines of weaknesses (A)

3. Notch ( narrow pass/cut) will be deepened to

produce a cave

4. Undercutting of the cave results in an overhanging

cliff (B)

5. Overhanging cliff may collapse (C)

6. Cliff retreats further inland with more erosion

7. The base of the cliff forms a gentle platform known

as the wave cut platform (D)

Formation of Cliffs and Wave cut platforms

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HeadlandsExtensions of bedrock jutting out into the sea usually with a cliff. Resistant towards erosion.

BaysBody of water connected to the seas due to surrounding land blocking off some waves

Definitions

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1. Waves approach the coasts comprising of

alternate strips of resistant hard rocks and

less resistant soft rocks.

2. The less resistant rocks will be eroded faster

than the more resistant hard rocks. (A)

3. When the softer rocks are eroded away, bays

are formed.

4. The remaining hard rocks extending into the

sea are known as headlands. (B)

Formation of Headlands and Bays

OverviewOverview

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Using a labelled diagram, describe the process of longshore drift [4]

1. Waves reach the coast at an oblique angle creates a longshore current

2. The materials move in a zigzag pattern in a down drift direction ( beach drift)

3. The swash carries materials up the beach at the same angle as when the wave approaches the shore

4. As the swash dies away, the backwash and any materials carries by it return straight down the beach at right angles to the water line due to gravity.

5. Longshore drift = beach drift + longshore current

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Wave refraction1. Waves usually approach

coast at an angle

2. But when it hits the headlands, the energy is concentrated and erodes the headlands

3. The energy is spread out as it moves towards the bay. Results in deposition of sentiments at the bay- forms beaches.

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The process by which waves are been or turned from its origin

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