Erosional Landforms Headlands and Bays Headland a piece

Erosional Landforms

Headlands and Bays • Headland = a piece of land jutting out into the sea • Bay = a broad coastal inlet often with a beach.

The Formation of Swanage Bay

Wave Cut Notch and Wave Cut Platform • Wave cut platform = a wide, gentle sloping rocky surface at the foot of a cliff. • Wave cut notch = a small indentation (notch) cut into a cliff roughly at the level of high tide caused by erosion.

Cliff Erosion and Wave-cut Platforms

Wave Cut Platform Formation Copy this diagram and see if you can match up the correct labels • 1. The sea attacks the cliff and undercuts it. Corrosion and hydraulic action cause a wave-cut notch • 2. The sea attacks the base of the cliff, when it collapses the line of the cliff retreats. • 3. The notch becomes larger and the weight of the cliff causes it to collapse • 4. As the cliff collapses the rubble is washed away by the waves leaving a wave-cut platform

The Sea Exploits Weaknesses in the Cliff Sea attacks a line of weakness opening up

Cave As the crack is eroded further, a cave is formed

Arch If the cave is eroded through the whole headland an arch is formed

Stack As the arch continues to be eroded it widens, until it eventually collapses leaving a stack Photo: David Lewis

Stump The stack is attacked by the weather and the sea. Slowly the rock is worn away and all that remains is a stump Photo: Ian Balcombe

Look at the picture of Old Harry, complete the sentences below to explain how it was formed. Old Harry is a ……………. . It was formed when an …………… collapsed. Old Harry will continue to be eroded by the ………. . And …………. . Until eventually it will become a ……………… Arch, sea, weather, stump, stack, wave cut notch, cave, destructive, constructive, hydraulic power, corrasion, attrition, cliff

Factors Affecting Coastal Erosion Rock type – Soft rock is easily eroded e. g. shale and clay. Soft rocks tend to form wide beaches. Hard rock is more resistant to erosion e. g. limestone and chalk. Hard rocks tend to form steep cliffs or rocky outcrops e. g. headlands Type of wave – The amount of energy a wave has will determine the amount of erosion that will take place. Destructive waves have a steep angle of break and are high in energy. They degrade beaches due the scouring action of the strong backwash

Factors Affecting Coastal Erosion continued Rock structure – When rocks are parallel to the coastline, the coastline is concordant and the amount of erosion will be determined by the resistance of the rock type forming the coastline. Where the rocks are at a right angle to the coast, the coastline is known as discordant, different erosion is likely to occur due to bands of hard and soft rock forming headlands and bays Shape of the Coastline – Where there are headlands these are exposed to the full force of the seas energy. Headlands can protect surrounding bays which can be sheltered from erosion.

Time to go for a walk along Swanage Pier and see if we can identify different erosional coastal features.