Landforms of Coastal Deposition (Beaches)- slides

• Landforms of Coastal Deposition

  They form on coastlines where sand and shingle accumulate faster than they are removed, also where there are low energy waves, and where coastal erosion provides an abundant supply of material
• Beaches


  Found where the land meets the sea, an accumulation of sediment deposited between low spring tide and the highest point reached by storm waves, made either of sand or shingle

  
• Sandy Beaches


  • Have a gentle gradient (below 5 degrees) due to small particle size, become compact when wet allowing little percolation so most swash returns as backwash, leading to formation of ridges and runnels in the sand at the low water mark
• Ridges and runnels


  Ridges are areas of the foreshore that are raised above the adjacent shore which dips into a runnel, the runnels are disrupted by channels that help to drain the water down the beach
• Shingle Beaches


  • Shingle may cover the whole beach or just the upper parts, the larger the material the steeper the gradient (10 to 20 degrees), water percolates quickly through shingle so backwash is not very strong and little material is carried down the beach
• Storm ridges and berms

  Spring tides form a storm ridge of largest material, following tides cannot reach these so they remain untouched, there are often a series of smaller ridges known as berms formed beneath the storm ridge

  
• Cusps


  Crescent-shaped indentations that form on beaches of mixed sand and shingle, formed where there is a junction between sand and shingle, swash is concentrated in the small bay that forms in the centre of the cusp creating a stronger backwash that removes material down the beach
• Ripples


  Developed on the sand by wave action or tidal currents
• Swash-aligned beaches


  Produced where the waves break in line (parallel) with the coast, swash & backwash movements move material up and down the beach so there is little long shore drift, smooth curved, concave beaches found on irregular coastlines where longshore drift is impeded

  
• Drift-aligned beaches


  Produced where waves break at an angle to the coast, swash occurs at an angle but backwash runs perpendicular to the beach, material is transported along the beach via longshore drift, can extend out from the coastline if there is a sudden change in direction