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Describe and Explain Factors Influencing Coastal Processes.

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Introduction

Describe and Explain Factors Influencing Coastal Processes In this essay I aim to describe and explain factors affecting coastal processes. I will focus and explore how waves, tides, winds and mass movement processes can change the form of the coasts within our lifetime. The three key questions I will focus on are: * What are the energy and sediment inputs into the coastal system? * What are the processes that erode coasts? * How is sediment transported and deposited? I will conclude by describing and explaining factors influencing coastal processes and how they make up the South Dorset coast. The littoral zone is a narrow zone between high and low water zones where energy and sediment concentrate. The sediments on the coast are sand, shingle and clay. The river, cliffs and sea are sources of sediment inputs into the coastal system. (Fig. 1) (Fig 1. Sediment inputs into the coastal system.) The energy inputs include wind, waves and tidal currents. The wind produces sand dunes on beaches with shallow offshore gradients; these produce ecosystems, which help with plants that cope with lack of nutrients and water etc. ...read more.

Middle

increases. When waves break, water runs up a beach, forming the swash and back toe beach as the backwash. Constructive waves are lower waves with a strong swash and weaker backwash that build up beaches. Destructive waves have a stronger backwash and erode material from the coast. There are four main ways in which waves cause erosion: 1. Abrasion/Corrasion occurs when the waves throw sand, shingle and pebbles against cliffs, grinding and breaking away the rock surface. 2. Corrosion happens when the acids in seawater dissolve rocks. 3. Hydraulic action results in the breakdown of rocks when waves breaking against the cliffs trap air in cracks causing pressure to build up. When the waves retreat the pressure is released breaking off fragments of rock. 4. Attrition occurs when pebbles and stones carried by the waves are broken up into smaller fragments as they are thrown against each other. These processes are quite simple but the patterns of erosion are complex as they are influenced by these four factors: 1. Rock type- its resistance to wave action and sub aerial processes and its solubility 2. ...read more.

Conclusion

this therefore changes the form of the south Dorset coast, areas such as Lyme Regis, Charmouth, West Bay, and Furzy Cliff, which have been affected mostly by erosion caused the factors mentioned above. The coastline in South Dorset has been divided into littoral cells on the basis of sediment pathways. Erosion is active along the majority of the coast and most noticeable when human developments have taken place on unstable softer rocks. I also found out that deposition occurs where the sea's energy for transportation is reduced and where an obstacle hinders the free movement of LSD material. A long groyne, such as one in Hengistbury Head, Dorset is an obstacle that causes sediment to be deposited, therefore causing the build up of the beach at south Dorset. Sediment moves southeast due to the dominant influence of LSD on the south Dorset coast, this is mainly on the Lyme Bay littoral zone. On the Weymouth Bay and Lulworth Coastal littoral zone; LSD moves material from west to east, whereas the sediment movement is east to west because the ebb tidal currents are greater than the tidal current and LSD. Nazia Zia Geography Essay 18/12/07 ...read more.

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