coasts

• A system is a set of interrelated objects comprising components(stores) and processes (links) that are connected together to form a working unit.
• Coasts are the zone where land and sea meet. They are also an open system because both energy and material can be transferred
• The different types of energy input are gravitational, solar, geothermal and kinetic, potential
• The different coastal materials are sand, shingles, mud, fluvial material and rockfalls.
• System feedback= when a systems inputs and outputs are equal in a state of equilibrium exists.
• Dynamic equilibrium= when a system is disturbed so it undergoes self regulation to correct the balance
• sediment cells= is a stretch of coastline and its nearshore area within the movement of sediment, it is self contained. There are 11 major ones in the UK. Large physical features act as natural barriers
• Waves are generated by the wind blowing across the surface of the water. They are caused by the frictional drag between the wind and the waves. They move in a circular motion to the individual molecules.
• Swell waves have a longer wavelength as they travel further and are slower. Whereas storm waves are locally generated meaning short wavelength/period and a greater height.
• Three different types of waves=

  spilling, plunging, surging
• Characteristics that alter waves= speed, fetch, duration, intermittency( a consistent wind)
• Tides are the periodic rise and fall of the sea surface produced by the gravitational pull of the moon, and to a lesser extent the sun
• Factors that influence tide are the shape and size of the ocean basin. The characteristics of the shoreline. The Coriolis effect caused by the earths rotation, water is deflected North or South. And meteorological conditions such as air pressure.
• high tides are created when gravitational forces of the moon creates a bulge of water when the moon is above .

  low tides is when the lack of gravity over regions the moon is not over. Earths rotation throws the water away from the earths surface.
• Tidal range= the difference in height between high and low tide.
• Tidal frequency= how often do tides happen

  Semi-diurnal= two high and 2 low tides in a lunar day

  diurnal= one high and one low tide in a lunar day

  Mixed= two high tides but at different extents
• Spring tides are when the sun and moon are aligned so their gravitational forces are combined making above average tides.

  Neap tides is when the sun and moon are aligned at a right angle and creates lower tides
• Lithology= physical and chemical properties of the rock

  Structure= properties of rock jointing, bedding, faulting and permeability of rocks.

  Discordant= several different rock types are perpendicular to the sea.

  concordant= one rock type is parallel to the sea.
• Ocean currents are generated from the earths rotation and transfer of heat, the heat travels north and south of the equator. This warmth can impact what types of weathering can occur.
• rip currents happen when two opposing long shore drift currents collide and therefore the water moves back out to sea as a rip current. Another way is that if there is an underwater bar this will block the backwash from returning water to the sea. As the water must return however it will find a gab in the bar and return creating current.

  Rip currents= a strong surface current flowing seawards from the shore.
• the sources of sediment can be terrestrial through rivers, deltas, erosion, deposition, weathering, cliffs, longshore drift.

  another source is Offshore, through constructive waves, tides, currents and winds.

  Humans are another source as they can transfer sediment
• Physical/mechanical weathering= weathering without chemical or biological causes.

  Freeze thaw weathering- when the rock freezes and expands by 9%, melted water gets into the cracks and repeatedly freezes over again.

  Salt crystallisation- salt solution into porous rock can evaporate allowing the salt to form crystals, they grow and cause the rock to fracture.
• Chemical weathering= weathering through chemical reactions between the atmosphere, temperature, moisture, minerals

  Hydration- water molecules added to rock minerals create new minerals of a larger volume. This expansion of around 0.5% can cause surface flaking.
• Biological weathering=Weathering caused by organisms

  organic acids- Blue green algae secretes iron that oxidises and causes the rock to break
• Types of mass movement (flows)-

  Soil creep= slow and continuous flow of soil particles

  Solifluction=moves about 1cm a year and is uncommon because it happens at the bottom layer of soil that is frozen. As the top layer become saturated it slides downhill over the frozen subsoil.

  Mudflow= An increase in water reduces the friction causing the mud to flow over rock
• Types of mass movement( slides)-

  Rockfall= On cliffs under 40 degrees, physical weathering detaches the rock which falls and forms slopes at the base of a cliff( reduce erosion)

  Linear= mass movement along a straight plane due to increased water

  Rotational slump= occurs when there is undercutting due to erosion so the cliff base removes support for the material above causing the slide. Common in weaker rocks
• Erosion processes

  abrasion, attrition, hydraulic action, solution, pounding

  Sediment is also derived from weathering and mass movement
• Transportation processes

  solution, suspension, saltation, traction, longshore drift
• Deposition processes

  Occurs when there is a loss of energy caused by a decrease in velocity and/or volume of wave.

  Factors that lead to deposition: Rate of sediment accumulation, when waves slow down, backwash, low energy environment.
• Deposition in a river

  As rivers enter the sea, reduction in velocity. Available energy is decreased, river load deposits. Larger sediment is dropped as the water loses energy so it cant carry anymore. meeting of fresh water and salt water causes flocculation of clay particles. This material clumps together and becomes heavier making it sink.
• Aeolian processes( Erosion)

  Wind is able to pick up sand particles(deflation), so sand is moved by surface rolling and saltation. Its heavier compared to clay so suspension occurs which has a limited effect. Erosive force increases exponentially with increase in wind velocity.
• Aeolian processes ( Transportation/ deposition)

  entrained= the flow of materials

  Moving air is also able to transport material through surface creep, solution, suspension

  Material in the wind falls when wind speed falls from surface friction
• shingle beaches is when sea levels were lower during the last glacial age, rivers deposited their sediment at a coastline that is submerged. As sea levels have risen over the last 25,000 years the sea has transported the sediment onshore.
• hard engineering= working to obstruct a natural process and is more expensive.
• soft engineering= working with natural processes to minimise change
• • Definition: Rias are coastal river valleys that have been flooded by rising sea levels.
  • Characteristics: They typically have a dendritic (tree-like) pattern and are characterized by gentle slopes leading to deeper waters.
• • Definition: Fjords are deep, narrow inlets formed when glacial valleys are submerged by rising sea levels.
  • Characteristics: These features are very steep and can be quite deep, often with a U-shaped profile due to glacial erosion.
• raised beaches

  former shore platforms and are at a higher level than current sea level.