Section 1; Systems

• What inputs act to shape coastal landforms

  Marine inputs via: Waves, Tides, Ocean (rip) Currents

  Energy inputs: Thermal energy (Sun-->Evaporation-->High/Low pressure-->winds, Kinetic (Frictional force on ocean surface=waves), G.P.E (of water particles at the Crest)
• Stores (landforms) 


  EROSIONAL:

  Headlands, Beaches, Cliffs, Wave-cut platforms

  Caves, Arches, Stacks, Stumps

  Geos and blowholes

  DEPOSITIONAL:

  Beaches and spits (LSD)

  Onshore/offshore bars, Tombolo's

  Saltmarshes, Dunes, Estuaries(Flocculation), Lagoons(LSD)
• Outputs

  • Removal of sediment (by Aeolian and Marine processes)
  • Removal of energy (via evaporation/cooling)
• Geology of the coastline is a major factor in the development of coastal landscapes:

  Lithology: types of rocks (igneous, metamorphic, sedimentary), cliff profile (Strata, Dip)

  Morphology(faults, cracks), Topography/relief
• Atmosphere is another major factor in the development of coastal landscapes:

  Climate change (emergent/submerging), Eustatic

  Climate- Cold/Hot Winters/Summers

  Mass movement and Weathering- Precipitation
• Littoral zone- area of the coastline subject to wave action
• Sub zones:

  Offshore: Area of deep water where waves begin

  Nearshore: Area of shallow water where waves break

  Foreshore: The area between High and low tide

  Backshore: Area above the high tide mark- only affected during high tide
• Sediment cell:

  Coast is considered as an open system but when the LITTORAL ZONE reaches dynamic equilibrium, inputs and outputs are balanced.

  In the UK the coastline can be split into 11 sections called sediment cells where the movement of coarse sediment, sand and shingle is largely self contained, Their boundaries are determined by the topography of the land. Yet these are not completely closed as some variations in winds may remove the sediment from the cells.
• Coastal vegetation: vegetations support sandy coastlines and prevents recession

  Sand dunes are consolidated together through the roots of plants e.g. Marram grass
• Freeze thaw weathering


  water enters cracks and joints and expands by nearly 10% when it freezes. In confined spaces this exerts pressure on the rock, causing it to split or pieces to break off, even in very resistant rocks
• Pressure release


  When overlying rocks are removed by weathering and erosion, the underlying rock expands and fractures parallel to the surface. Parallel fractures are sometimes called pseudo-bedding planes
• Thermal expansion


  Rocks expand when heated and contract when cooled. If they are subject to frequent cycles of temperature change then the outer layers may crack and flake off. Also known as isolation weathering
• Salt crystallisation


  Solutions of salt can seep into the pore spaces in porous rocks. Here the salts precipitate, forming crystals. The growth of these crystals creates stress in the rock causing it to disintegrate. Sodium sulphate and sodium carbonate expand by about 300% in areas of temperatures around 26-28c
• Oxidation


  Some minerals in rocks react with oxygen, either in the air or water e.g. Iron. It becomes soluble under extremely acidic conditions and the original structure is destroyed. It often attacks the iron-rich cements that bind sand grains together in sandstone
• Carbonation


  Rainwater combines with dissolved carbon dioxide from the atmosphere to produce a weak carbonic acid. This reacts with calcium carbonate in rocks such as limestone to produce calcium bicarbonate, which is soluble. This process is irreversible and precipitation of calcite happens during evaporation of calcium rich water in caves to form stalactites and stalagmites
• Solution


  Some salts are soluble in water. Other minerals, such as iron, are only soluble in very acidic water with a pH of about 3. Any process by which a mineral dissolves in water is known as solution. Some can be identified such as carbonation
• Hydrolysis


  This is a chemical reaction between rock minerals and water. Silicates combine with water producing secondary minerals such as clays. Feldspar in granite reacts with hydrogen in water to produce kaolin
• Hydration


  Water molecules added to rock minerals create new minerals of a larger volume. This happens when anhydrite takes up water to form gypsum. Hydration causes surface flaking in many rocks, partly because some minerals also expand by about 0.5% during the chemical change because they absorb water
• Tree roots


  Tree roots grow into cracks or joints in rocks and exert outward pressure. This operates in a similar way to freeze-thaw. When trees topple, their roots can also exert leverage on on rock and soil, bringing them to the surface and exposing them to further weathering. Burrowing animals may have a similar effect
• Organic acids.bio weathering


  Organic acids produced during decomposition of plant and animal litter cause soil water to become more acidic and react with some minerals in a process called chelation. Blue-green algae can have a weathering effect, producing a shiny film of iron and manganese oxides on rocks. On shore platforms molluscs may secrete acids which produce small surface hollows in the rock