Geography - Coasts

Contents Introduction HAAC Processes Wave Types Headlands and Bays Wave-cut notches + Wave-cut platforms Stacks and stumps Long Shore Drift Spit, Bars and Tombolos Erosion Rate Chart Glossary Bibliography

Introduction To Coasts. I like trains and bum

The Marine Processes (HAAC) The Marine Processes (HAAC Processes) are the processes performed by the waves that erode the coast. These Processes are: Hydraulic Action – This is where the shear force of the waves get into cracks in rock and break it away. Attrition – This is where rocks in the waves hit against each over making smaller, rounder rocks. Abrasion – This is where rocks are thrown at the cliff when the waves break. Corrosion (solution) – This is where chemicals in the water react with minerals in the rock, breaking down the rock.

Wave Types Constructive Waves: Constructive waves build up the beach by bringing material onto the beach. They have a strong swash and a weak backwash.

Wave Types Destructive Wave: Destructive waves take material off the beach. They have a weaker swash but a strong backwash.

Headlands And Bays A headland is a large piece of rock that sticks out perpendicular to the coast. They are usually formed when bays are formed, by differential erosion. Differential erosion is where rocks erode at different rates. When there is soft rock in the middle of harder rocks, the soft rocks erode quicker, forming a bay, and two headlands. Headlands form on discordant coastlines.

Wave - Cut Notches And Platforms Wave-cut notches and platforms are features that form on hard rock coastlines. They are formed by the Marine (HAAC) processes. Wave-cut Notch Wave-cut notches are formed when the cliff is eroded between high and low tide levels. The erosion leaves an indentation at the base of the cliff. This is a wave-cut notch. Wave-cut Platform Wave-cut platforms are formed when the cliff again erodes between high and low tide level making a wave-cut notch. Then, because the base is weak, the cliff on top collapses and the debris is taking away. This happens again until the cliff has receded (cliff recession) leaving a hard rock platform.

Stacks And Stumps Stacks and stumps are features that form on hard rock, discordant coastlines. The process starts when there are faults (cracks) in a headland. These cracks are then widened and eroded by sub aerial processes, like freeze thaw weathering, and marine processes. Eventually a cave is made. These caves are then eroded by the marine processes until it Is eroded all the way through. This creates a arch. Next, the roof of the arch is eroded by sub aerial processes. This causes the roof to collapse. This leaves a stack. Once the stack is eroded, it falls over and a stump is left.

Long shore Drift Long shore drift is the process where material is moved up or down the beach. This causes one end of a beach to have lots of sand, while the other has little. Long shore drift causes other problems. For example, when the beach has little sand, the waves break further up the beach. This means cliffs are eroded faster. Long shore drift starts with the prevailing wind. This makes the swash angled. Then, due to gravity, the backwash is straight. This creates a zig zag motion. Because of this motion, material moves diagonal up the beach then straight down. This is repeated. Eventually material that started at one end of a beach, will end up at the other. Start End

Spits, Bars and Tombolos Spits, bars and Tombolos are depositional features that are created due to Long Shore Drift. They form when the coastline changes direction.

Erosion Rate Chart

Series 1 Series 2 Series 3 Scarborough 4.3 2.4 2 Happisburgh 2.5 4.4 Sea Palling 3.5 1.8 3 Dorset 4.5 2.8 5 Holderness 4 3.9 5.4

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Glossary Marine Processes: Erosional processes that occur in the water. (HAAC Processes) Constructive Wave: Waves that take material on to the beach. Destructive wave: Waves that take material off the beach. Swash: When the water comes on to the beach. Backwash: When he water runs back into the sea. Headlands: Large pieces of large rock that stick out perpendicular to the sea. Bays: A gap in-between two headlands where differential erosion has occurred. Differential Erosion: Where rocks erode at different rates. Discordant Coastline: Where rocks are perpendicular to the coast. Wave-cut Notch: An indentation at the base of a cliff, cause by HAAC Processes. Wave-cut Platform: A rock platform left after cliff recession. Cliff Recession: Where cliffs move back as they get eroded. Stacks: A erosional feature created off a headland. Stump: A erosional feature created off a headland. Faults: Cracks in a rock. Sub aerial Processes: Processes that attack the top of the cliff. Long Shore drift: The process that moves material down the beach. Prevailing Wind: The dominant wind direction.

Bibliography www.bbc.co.uk/schools/gcsebitesize/geography/coasts