GCSE Geography Mind Map on Coasts, created by humaira gafar on 24/03/2016.
humaira gafar
Mind Map by humaira gafar, updated more than 1 year ago
humaira gafar
Created by humaira gafar almost 8 years ago

Resource summary

  1. Erosion is the process of wearing away and breaking down of rocks in that area. Coasts made of hard rocks are worn away over hundreds of years, with most of the erosion occurring during storms-when waves are most powerful.
    1. Types of weathering
      1. Chemical Weathering-from acidic rainfall which dissolves weak minerals and causes rocks to decay
        1. Mechanical weathering-Growth of salt crystals causes stresses in the rock which later breaks.
          1. Biological weathering- From plants which cause rocks to break, e.g with roots,stems and branches.
          2. Coastal Transportation
            1. Suspension- Fine sediment is carried as suspension in the water, this is what makes water looks dirty.
              1. Solution- Dissolved material is carried along and you cant see it.
                1. Traction- Bigger pebbles and cobbles are rolled along the sea bed.
                  1. Saltation- Small pebbles moved when one pebble hit another,making it bounce. This bouncing sets up a reaction.
                    1. Longshore drift is another way of coastal transportation. The first thing that happens is that the waves approach the beach at a 45 angle, because the waves break the swash would carry material and deposit up to the beach because gravity is available some material might be taken away due to the backwash of the waves. This means the sediment movement would be moved along in a zig zag route. The movement of material is known as longshore drift.
                      1. Process for longshore drift
                    2. Waves
                      1. Destructive Waves - Waves that have a weak swash and a strong backwash pull sand and pebbles back down the beach when the water retreats. They are called destructive waves because they remove material from the beach. They are often steep, high waves that are close together and crash down on to the beach.
                        1. Constructive Waves - These are waves that have a strong swash but a weak backwash. due to this these waves build up the beach. They push sand and pebbles up the beach and leave them behind when the water retreats, this is because their backwash is not as strong enough to remove the material. They are often low waves with longer gaps between them
                          1. The size of a wave is dependable on many factors, for example how strong and how long the wind blows for. Fetch is how far a wave has travelled in a given time.
                          2. Mass Movement
                            1. Mass Movement is when rocks loosened by weathering move down slope under the influence of gravity.
                              1. Rockfalll / sliding - This is one of the ways how rock can loosen. This is the process when huge rocks would sllide down the slope quickly without any warning. This can make it hazardous for people to walk across the beach. Rock fragment are fallen off the steep cliff due to the influence of gravity.
                                1. Slumping is another process of mass movement this is where when cliffs are made of clay. Due to the clay becoming saturated during heavy rainfalll it would ooze down towards the sea as part of a mud or debris.
                              2. Coastal erosion
                                1. Hydraulic Action- This is when strong waves crash into the cliff face. The trapped air is blasted into holes and cracks in the rock causing them to break apart.
                                  1. Attrition - Rock fragments carried by the sea knock into each other, they break down and become smaller and rounded.
                                    1. Abrasion - Fragments of rock are picked up and hurled at the cliff by the sea. They scrape and gouge the rock.
                                      1. Solution- Chemical action of the water where salts and acids in the water can dissolve rock.
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