Download - Beach Profiles
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Beach Profiles
AS Geography
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Learning Objectives
• Understand that beaches contain different landforms created by deposition
• Look at the associated features of beaches
• Understand the key terms and factors that dictate how each feature is formed
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What is a beach Profile?
• What can you tell me about beaches?• The are full of sediment• They constantly change• They are a store of inputs• They are the source of outputs• They are buffer between the land and the
sea
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Most Beaches have 3 main components
• Nearshore• Foreshore• Backshore
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Nearshore
• What factors affect the nearshore
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Nearshore
• Zone extending seaward of the shoreline well beyond the breaker zone. Zone in which nearshore currents occur.
• The gentle gradient results from the smoothing out of sediment associated with the back and forth movement of the waves
• Due to the loss of energy, some sediment can be deposited in sand bars
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Foreshore
• What factors affect the foreshore?
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Foreshore
• Once a wave breaks, its water moves as a sheet upslope as swash, and falls back toward the sea as backwash. The narrow area in which this occurs is called the swash zone.
• The location of swash zone shifts due to the rising and falling of the water level, associated with tides.
• The area affected by the swash zone on a daily basis is called the foreshore (between low and high tide marks)
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• As the flow of swash slows (and eventually stops) in its upper reaches, some of the sediment carried by the water can be deposited.
• But much of the sediment is returned back down to the upper shoreface due to backwash.
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Describe the changing characteristics of the storm beach from SW to NE. (7 marks)
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Backshore
• What effects the backshore?
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Backshore Zone
• Beyond the Foreshore is a backshore zone, characterized by dunes.
• Sediment can also be transported to the backshore area during storms, when big waves can reach far inland.
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The features
Berms • A nearly horizontal or landward-sloping portion of a beach,
formed by the deposition of sediment by storm waves
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Ridges and Runnels
• Ridges are areas of the foreshore that are raised above the adjacent shore which dips into a Runnel. The cross-section is similar to that of hills and valleys.
• Ridge and Runnel Systems are formed due to the interaction of tides, currents, sediments and the beach topography. They will only form on shallow gradient beaches
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Cusps
• Beach cusps are rhythmic shoreline features formed by swash action
• They develop in a variety of environments but commonly on coarse-grained beaches with low wave energy
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Spits
• long narrow ridges of sand and shingle which project from the coastline into the sea.
• They begins due to a change in the direction of a coastline - the main source of material is from longshore drift
• Where there is a break in the coastline and a slight drop in energy, longshore drift will deposit material at a faster rate than it can be removed and gradually a ridge is built up, projecting outwards into the sea
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Bars
• A bar may form where there a changes in coastal direction and drop in tidal energy creating sedimentation
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Using pages 93 to 96 answer these questions:
• Distinguish between a spit, bar and tombolo
• Outline three pieces of evidence that indicate the direction of longshore drift along a coastline.
• Using an example(s), describe the main features of a spit. (Draw annoted sketch)
• Choose either a beach or a spit. Describe the chosen landform and explain the role played by longshore drift in its formation