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Coastal landforms LS: Explain the formation of erosional coastal landforms using vast key words. Describe the process of longshore drift and describe the.

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Presentation on theme: "Coastal landforms LS: Explain the formation of erosional coastal landforms using vast key words. Describe the process of longshore drift and describe the."— Presentation transcript:

1 Coastal landforms LS: Explain the formation of erosional coastal landforms using vast key words. Describe the process of longshore drift and describe the formation of Depositional landforms by the effect of Longshore drift.

2 Starter Activity Read through the content about seas from your KS3 booklet, and answer the below questions: 1) What is the name given to the distance between two complete sea waves? 2) Describe the difference between constructive and destructive waves 3) Why are destructive waves more violent than constructive waves? 4) Explain the process of Longshore drift Keywords you need to learn: Constructive waves: Gentle sea waves, which flow during warm and calm weather conditions. Destructive waves: Large waves up to 10-20 feet which flow more violently in stormy weather conditions. Longshore drift: The flow of sea waves in an angle towards the coastline

3 Basics of longshore drift Longshore drift is the process in which sea waves come towards the shore at an oblique angel (Diagonal) As they flow up the beach, they drop off eroded material because of the shallow area slowing down the waves speeds. The name given to sea waves as they move up the beach at an angle is called Swash. As the waves come back off the beach, this is called backwash, carrying back some of the smaller material. Longshore drift erodes beaches and can cause problems, and there are ways of which thiese erosion problems are dealt with. A hard engineering strategy is a strategy which focuses on the beaches physical attributes, to stop erosion and flooding. Groynes are built into the coastal waters at a 90' angle, so that the incoming waves of longshore drift, they reduce the movement of the material and hold the beach in place. As they protect the beach, the shore will not be eroded as much more, because the swash is not occurring.

4 Erosional landscapes formed by Erosion A cliff is formed when sea waves smash against the rocks on the shoreline, as the waves hit the rocks, they are eroded by Hydraulic action, abrasion and wave pounding, as the waves hit, they create a notch slowly, by the erosion, a notch can eventually erode to form a Cave. As erosion continues at this notch as well as weathering taking place at the top, the land will eventually become un-stable and collapse in forming a cliff. Cliffs retreat. As erosion continues at the wave cut platform, the cliff continues eroding, forming a large platform, thus called a Wave cut platform.

5 Headlands and bays Where the shore is formed from layers of softer and harder rock called alternate bands of rock, the softer rock is more easily eroded, whilst the harder rock is harder to erode, as the soft rock is broken down, by cliff formation, they are left with bays, the harder rock is left jotted out into the sea, where erosion continues, this jotted out area of land are called Headlands. Most bays usually have a lot of deposited material entering, thus forming beaches on these bays. An example is Cardigan bay in Wales The geology of the area will affect the size and formation of headlands and bays, for example, the harder rock could be all limestone whist the softer rock is all Clay. The softer rock will be easily eroded and Limestone may take years to erode

6 Caves, Arches, stacks and Stumps A cave is formed when erosion of a cliff creates a notch, as this notch continues to erode, the cave is formed, the cracks in headlands are weakened points of a cliff so can easily be eroded into. An arch is formed as air compressed into caves by the power of waves weakens the roof of the cave and this roof becomes weakened along a major joint and the rock collapses to form a blow hole, as this hole is continued eroded the arch is made larger. Above the arch, the roof becomes unstable, as this roof becomes eren more unstable it eventually collapses and leaves a stack or stump, usually this continues to happen to form a hole range of stacks.

7 Depositional landforms – Beaches, spits, Barrier beaches and Tombolos A beach is formed in shallow waters near the shore, as the sea's current is slow, it drops off more material, this deposited material eventually becomes a beach. Spits are formed through the process of Longshire Drift, as the sea waves come towards a beach at an angle, the continuous erosion and deposition begin creating a long narrow edge to the beach, as this continues the spit will be formed, with a beach that continues down a narrow short edge, with a marsh area. Barrier beaches are formed when spits are being formed, as the spit forms, the depositional material will keep building up and eventually block off a bay, this blocked back is then known as a lagoon, a sort of lake. It is called a barrier beach because it is a beach which blocks off a bay. Tombolos are where deposition occurs, it basically is the term given to the piece of land connecting an island to the mainland, the depositional material builds up and creates a small ridge piece of land which connects to the mainland.

8 Exam style questions 1) Study figure 6c which shows the direction of Longshore drift. a) State what is meant by the term “Swash” …..................................................................................................................................... b) Describe how the type of waves can effect the erosion and deposition occurring by Longshore drift …............................................................................................................................................................................................................................................................................. c) As Longshore drift continues to deposit material onto the beaches, it begins to form a landform called a spit. Fully describe the formation of splits. …............................................................................................... *d) Coastal flooding is a major effect towards the beach and the people of the area, explain the hard and soft engineering strategies in maintaining the flooding of coasts.


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