1.3 developed

• Weathering 

  -weathering uses energy to produce physically or chemically altered materials from surface or near surface rock
• Physical or mechanical 

  -the breakdown of rock is largely achieved by physical weathering processes that produce smaller fragments of the same rock

  -by increasing the exposed surface area of the rock, physical weathering allows further weathering to take place
• physical/ mechanical weathering examples 

  -freeze thaw- water enters cracks/ joints and expands when it freezes, in confined spaces this experts pressure on the rock causing it to split or pierces to break of 

  -pressure release- when overlying rocks are removed by weathering and erosion, the underlying rock expands and fractures parallel to the surface 

  -thermal expansion- rocks expand when heated and contracts when cooled, if there's frequent cycles of heating and cooling the outer layers may crack and flake off 

  -Salt crystallisation- solutions of salt can seep into porous rocks 
• -Salt crystallisation- solutions of salt can seep into porous rocks 

  Chemical 

  -the decay of rock is the result of chemical weathering which involves chemical reactions between moisture and some minerals in the rock

   -chemical weathering processes produce weak residues of different material that may then be easily removed by erosion or transportation processes

  -most chemical weathering process occur at higher rates in tropical rather than temperate or polar regions
• Chemical weathering examples 

  -oxidation-some minerals in rocks react with oxygen, either in the air or in water, it becomes soluble under extremely acidic conditions and the original structure is destroyed 

  -carbonation- rainwater combines with dissolve carbon dioxide which reacts with calcium carbonate in rocks

  -hydrolysis-this is a chemical reaction between rock minerals and water, silicates combine with water, producing secondary minerals such as clays

  -hydration- water molecules added to rock mine®as create new minerals of a larger volume, it causes surface flaking in many rocks  
• Biological weathering examples 

  -tree roots- they grow into cracks or joints in rocks and exert outward pressure, when trees topple their roots can also exert leverage onto rock and soil bringing them to the surface and exposing them to further weathering
• biological weathering example

  -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 molluscs may secrete acids which produce small surface hollows on the rock
• Erosion

  Abrasion- when waves armed with rock particles scour the coastline, rock rubbing against rock 

  Attrition- occurs when rock particles, transported by wave action, collide with each other and with coastal rocks and progressively become worn away, eventually producing sand 

  Hydraulic action- waves break against a cliff face and air and water trapped in cracks and crevices become compressed, the air suddenly expands and the crack is widened 

  Pounding- when the mass force of a breaking wave exerts pressure on the rock causing it to weaken
• Transportation

  Solution- minerals that have been dissolved into the mass of moving water 

  Suspension- small particles of sand silt and clay can be carried by currents

  Saltation- a series of irregular movements of material which is too heavy to be carried continuously in suspension, other particles may be dislodged by the impact, allowing water to get beneath them and cause entertainment 

  Traction- the largest particles in the load may be pushed along the sea floor by the force of the flow, although this can be called rolling
• Deposition tends to take place in coastal landscape systems 

  -where rate of sediment accumulation exceeds the rate of removal

  -when waves slow down immediately after breaking 

  -at the top of swash, where for a brief moment the water is no longer moving 

  -during backwash, when water percolates into the beach material 

  -in low energy environments, such as those sheltered from winds and waves 

  The velocity at which sediment particles are deposited is known as the settling velocity, the larger and heavier particles require more energy to transport them 
• Fluvial processes 

  Fluvial processes often play an important part in the development of landforms. 
• Erosion

  Fluvial erosion in the upper catchment is the main source of a river's sediment load, with most channel erosion occurring during high-flow, high energy events. Sediment is also derived from weathering and mass movement processes that result in material moving into a river channels from the valley sides 

  Transportation- rivers also transport sediment by traction, suspension, saltation and solution, similar processes of those waves 
• Deposition -Tides and currents may be moving in opposite direction to the river flow, providing a major resistance to its forward movement, available energy is reduced and so some or all of the rivers sediment load is deposited

  The meeting of freshwater and saltwater causes flocculation of clay particles. These fine, light materials clump together due to electrical charges between them in saline conditions. As a result they become heavier and sink to the sea bed.
• Aeolian processes 

  erosion-Wind is able to pick up sand particles and move them by deflation as grains of this size are relatively heavy, compared with silt and clay particles, they are carried in suspension. Dry sand is much easier for wind to pick up than wet sand, as the moisture increases cohesion between particles, helping them to stick together.
• aeolian processes

  Deposition- Material carried by wind will be deposited when the wind speed falls, as a result of surface friction. In coastal areas this will occur inland,where friction from vegetation and surface irregularities is more than on the open sea.
• Cliffs and shore platforms- When destructive waves break repeatedly on relatively steeply sloping coastlines, undercutting can occur between the high and low tide levels where it forms a wave-cut notch. Continued undercutting weakens support for the rock strata above, then collapses, producing a steep profile and a cliff.

  Cliff profiles vary depending upon their geology, horizontally bedded and landward dipping rock strata support cliffs with a steep, near vertical profile. If the rock strata inclines seaward, the profile tends to follow the angle of the dipping strata.
• (cliffs and shore platforms) Where rock debris is boulder-sized, it may be too large to be removed by the waves and will accumulate on the platform. Eventually, the platform will become so wide that it produces shallow water and small waves

  Friction from the platform slows down approaching waves sufficiently for them to break on the platform rather than at the base of the cliff and so undercutting slows and eventually ceases.Solution, freeze-thaw and salt crystallisation may all take place, depending upon the rock type and the climatic conditions of the location.
• Algae can accelerate weathering when the platform is exposed at low tide because at night it releases co2 (photosynthesis is not taking place), it then mixes with seawater making it more acidic therefore increases chemical weathering.
• Bays and headlands- typically form adjacent to each other usually due to the presence of different bands of rocks of differing erosion, weaker rocks are eroded more rapidly to form bays while the more resistant remain between the bays and headlands, this causes the formation of a discordant coastline 
• bays and headlands-

  Rocks lying parallel to the coastline produce concordant coastline, if most resistant rock lies seaward it protects any weaker rocks, however small bays or coves may be ordered due to points of weakness, such as fault lines

  When waves approach irregularly shaped coastline, wave refraction takes place

  At the same time the part of the wave crest in the deeper water approaching the bay moves faster as its not being slowed by friction, means the wave refracts around the headland, therefore wave energy is focused on the headland and erosion is concentrated there 
• Geos and blowholes- geos are narrow steep sided inlets, they are eroded more rapidly by wave action than the more resistant rock around them. Hydraulic action may be particularly important in forcing air and water into the joints weakening the rock strata. Sometimes geos initially form as tunnel like caves running at right angles to the cliff line

  If part of the roof of a tunnel like cave collapses it may form a vertical shaft that reaches the cliff top. This is a blowhole, in storm conditions large waves may force spray out of blowhole
• Depositional landforms 

  Beaches- beach material comes from 3 main sources- cliff erosion, offshore, combed from sea bed, rivers 

  Sand produces beaches with a gentle gradient, it becomes combat when wet allowing little percolation during backwash. As little energy is lost to friction and little volume is lost due to percolation material is carried back down the beach rather than being left at the top, resulting in a gentle gradient and the development of ridges and runnels parallel to the shore 
• Storm waves- hurl pebbles and cobbles to the back of the beach forming a storm beach/ storm ridge 

  Berms- smaller ridges that develop at the position of the mean high tide mark, resulting in the deposition at the top of swash
• Cusps- small, semi-circular depressions, temporary features formed by a collection of waves reaching the same point and when swash and backwash have similar strength, the side of cusp channel incoming swash into the centre of the depression and this produces a strong backwash which drags material down the beach from the centre of the cusp enlarging the depression 

  Further down the beach ripples may develop in the sand due to the orbital movement of water in waves
• Beach profiles can be measured to

  -compre beaches or coastline in different locations

  -examine the effects of management on beach processed 

  -investigate season changes in the beach profile

  -examine relationships between the beach profile
• Spits- long narrow beaches of sand/shingle that are attached to the land at one end and extend across a bay, estuary or indentation in a coastline

  Formed by longshore drift occurring in one dominant direction which carried beach material to the end of the beach and then beyond into the open water 

  As storms build up more and larger material they make the feature more substantial and permanent 

  The end of the spit sometimes becomes recurved because of wave refraction 

  Overtime spits may continue to grow a number of recurves or hooked ends may develop 
• In the sheltered are behind the spit deposition will occur as wave energy is reduced, the silt and mud deposited will build up and eventually salt tolerant vegetation may colonise, leading to the formation of a salt marsh 
• Onshore bars- onshore bars can develop if a spit continues to grow across an indentation such as a cove or bay in the coastline until it joins onto the land at the other end, this forms a lagoon 
• Tombolos- they are beaches that connect the mainland to an offshore island, often form spits that have continues to grow seawards until they reach and join inland
• Salt marshes- features of low energy environments, such as estuaries 

  Salt marshes are vegetated areas of deposited silt and clays, salt tolerant plant species help trap sediment and gradually help to increase the height of the marsh . the stems and leaves of the plant trap sediment swept in by the tidal currents while the roots stabilise the sediment 

  Few plant species can survive such conditions and so species diversity is poor 

  They have a shallow gradient which slopes seawards, deposition rates are still quite high as a high water mark
• salt marshes

  The greater density of vegetation cover helps to trap and stabilise sediment, extensive networks of small, steep sided channels or creeks, drain the nurse at low ride and provide routes for water to enter the salt marsh as the tide rises 

  The development of salt marshes depends on the rate of accumulation of sediment 

  In salt water the particles are attracted to each other combining together to form flocs, which means they are unable to be carried in the river flow and so settle out of suspension
• Deltas - deltas are large areas of sediment found at the mouths of many rivers

  They form when rivers and tidal currents deposit sediment at a faster rate than waves and tides can remove it

  They typically form where, rivers entering the sea are carrying large sediment loads, a broad continental shelf margin exists at the river mouth to provide a platform for sediment accumulation, low energy environment exist in the coastal areas, tidal ranges are low 
• The structure of deltas:

  The upper delta plain- furthest inland, beyond the reach of tides and composed entirely of river deposits 

  The lower delta plain- in the intertidal zone, regularly submerged and composed of both river and marine deposits 

  The submerged delta plain- lies below mean low water mark is composed mainly of marine sediments and represents the deaward growth of the delta 
• the structure of deltas

  They are criss crossed by a branching network of distributors overloaded with sediment, deposition in the channel forms bars which causes the channel to split into two, this produces two channel with reduced energy levels and so more deposition and diving occurs