Coastal Landscapes

Aims:• To know how the coastline is shaped.• To understand the different types of wave

and their characteristics.• To be able to explain the different types of

weathering, erosion and mass-movement.

The coast is under attack through a variety of processes:

• Erosion

• Weathering

• Mass-movement

Weathering or Mass-Movement?

Slumping

Chemical

Weathering

Biological Weathering

What other forms are there?

Attrition

Hydraulic action

Abrasion

Corrosion

Processes of erosion

AttritionMaterial carried by the waves bump into each other and so are smoothed and broken down into smaller particles.

Abrasion/CorrasionThis is the process by which the coast is worn down by material carried by the waves. Waves throw these particles against the rock, sometimes at high velocity.

Hydraulic ActionThis process involves the force of water against the coast. The waves enter cracks (faults) in the coastline and compress the air within the crack. When the wave retreats, the air in the crack expands quickly causing a minor explosion. This process is repeated continuously.CorrosionThis is the chemical action of sea water. The acids in the salt water slowly dissolve rocks on the coast. Limestone and chalk are particularly prone to this process.

Weathering is the natural breakdown of rocks at the earth’s surface.

Using Geographical Foundations pgs 57-58.

Task:1. Describe and explain the 3 main types

of weathering.2. What is mass-movement?3. What are the different types?

What affects the rate of coastal erosion?

Waves are the main agents of erosion at coastlines. Wave action and power depends upon different factors.

What factors affect waves?

Why are waves generally larger in the south west than in the south east?

Wave energy depends on the fetch, the strength of the wind and the length of time over which the wind has blown.

Complete Activity 1 on pg 57.

fetch = the distance over which the wind has blown

Destructive waves Constructive waves

Waves can either be…

Tasks:

1. Copy the diagrams of figure 1 and figure 2 on page 56.

2.Describe how these waves are different and add a summary using page 57.

Breaking waves cause two movements:

• Swash moves up the beach

• Backwash moves straight down the beach

Backwash

Swash

Remember: Backwash is always at right angles to the beach!

Swash and backwash

Constructive Waves

Spilling Breaker

Weak BackwashPowerful Swash

DEPOSITS MATERIAL

Destructive Waves

Crashing breaker

Weak swash

Powerful Backwash

ERODES MATERIAL