3.1 The Coastal system 3.5.1 Erosion 3.5.2 Transportation

Systems terminology helps us to understand the connections between processes and The break down and transport of rocks – smooth, A natural process by which eroded material is round and sorted. carried/transported. Input Material or energy moving e.g. precipitation, wind into the system from outside Attrition Rocks that bash together to become Solution Minerals dissolve in water smooth/smaller. and are carried along. Output Material or energy moving e.g. ocean currents, rip tides, sediment transfer, from the system to outside evaporation Corrosion A chemical reaction that dissolved Suspension Sediment is carried along in rocks. the flow of the water. Energy Power or driving force e.g. energy associated with flowing water, the effects of gravity on moving cliffs Corrasion Rocks hurled at the base of a to Saltation that bounce along break pieces apart. the sea/river bed. Stores / components The individual elements or e.g. , parts of a system Hydraulic Water enters cracks in the cliff, air Traction Boulders that roll along a Action compresses, causing the crack to river/sea bed by the force of Flows / transfers The links or relationships e.g. wind-blown sand, , mass expand. the flowing water. between components movement

Positive feedback Where a flow/transfer leads e.g. can lead to an increase in to increase or growth erosion elsewhere along the

Negative feedback Where a flow/transfer leads e.g. when the rate of weathering and mass movement to a decrease or decline exceeds the rate of cliff-foot erosion

Dynamic equilibrium A state of balance within a e.g. constructive waves build up a beach, making it constantly changing system steeper. This encourages the formation of destructive waves that plunge redistributing the sediment. Unit 1, Section B, Topic 3 3.5.3 Deposition 3.2.1 How are waves formed? Coastal systems and landscapes When the water looses energy transported The formation, size and shape is a result of the exchange of energy from sediment is dropped. wind blowing over the sea. 3.3 Sediment sources, cells and budgets 3.4.1 Weathering Rivers are the main source of coastal sediment. Other sources include cliff erosion and offshore marine erosion The breakdown or decay of rocks. Sediment cells Sediment budgets Mechanical - Largely self contained natural systems - The total sediment in a sediment cell - Usually found between two Losses The break-up of rocks without any chemical - The movement of sediment is pretty much - Deposition into sediment sinks changes e.g. frost shattering, salt contained Gains crystallisation, wetting and drying. Inputs (sources) - Chemical - River and coastal erosion - Sediment brought into the system by rivers or 3.2.2 Different types of waves Transfers other offshore sources. A chemical reaction e.g. carbonation, - Longshore drift oxidation and solution. There are two main types of wave: constructive and destructive - Rip currents Stores (sinks) Biological Formation Distant weather systems Local storms - in the open ocean - Sand dunes The breakdown of rocks by organic activity e.g. plant roots, burrowing animals and birds. Wave form Low, surging. Long High, plunging. - Bars wavelength Short wavelength 3.4.2 Mass movement Wave break String , weak Weak swash, strong backwash backwash The downhill movement of material under the influence of gravity. This can be classified into Beach Beach gain Gentle Beach loss. Steeper creep, flow, slide and fall. profile profile 3.6.1 Landforms of erosion: cave, arch, , stump 3.6.2 Landforms of erosion: Headlands and bays 3.8.1 Sea level change

Soft rock 1) Waves attack the coastline. Sea levels respond to climate change, in particular the onset of glacial and interglacial 2) Softer rock is eroded by the sea periods. quicker forming a bay, calm area Hard rock cases deposition. Eustatic change Isostatic change 3) More resistant rock is left jutting out into the sea. This is a and is - Changes in seal level (rise or fall) - The land itself changes in height, now more vulnerable to erosion. Headland relative to the sea

3.7.1 Landforms of deposition: 3.8.2 Landforms caused by changing sea level

Emergent coastline Submergent coastline

1) Hydraulic action widens cracks in the cliff face over time. - A fall in sea level exposes land - A rise in sea level floods the coast. 2) Abrasion forms a wave cut notch between HT and LT. previously covered by the sea. 3) Further abrasion widens the wave cut notch to from a cave. 4) Caves from both sides of the headland break through to form an arch. Raised beaches 5) Weather above/erosion below –arch collapses leaving stack. 6) Further weathering and erosion eaves a stump. When wave-cut platforms and their Sheltered, winding formed when a beaches are raised above the present sea rise in sea level drowned river valleys 3.9 Coastal management level. 1) Swash moves up the beach at the angle of the prevailing wind. 2) Backwash moves down the beach at 90° to coastline, due to gravity. Hard Engineering Defences 3) Zigzag movement (Longshore Drift) transports material along beach. 3.8.3 Contemporary sea level change Wood barriers Beach still accessible. 4) Deposition causes beach to extend, until reaching a river . prevent No deposition further 5) Change in prevailing wind direction forms a hook. - Until recently sea levels have been Formed when deep glacial troughs are longshore drift, down coast = erodes 6) Sheltered area behind spit encourages deposition, forms. stable for the past 3000 years. flooded by a rise in sea level so the beach faster. - Over the 20th century global sea levels can build up. 3.7.2 Landforms of deposition: Beach have rose by 1.7mm per year. Dalmatian Sea Walls Concrete walls Long life span - By 2100 it is estimated that sea levels could have increased by up to 1m. break up the Protects from flooding Formed when valleys running parallel to the - This increase is largely due to thermal energy of the Reflects energy rather coast are flooded by a rise in sea level. wave . Has a lip than absorbing it. expansion od water due to warming to stop waves and the melting of ice. going over.

Rip Rap/rock Cages of Cheap 3.7.5 Landforms of deposition: 3.7.6 Landforms of deposition: armour rocks/boulders Local material can be Barrier beach (bars) Offshore bar absorb the used to look less waves energy, strange. Where a beach or spit extends across a bay Are submerged or partly exposed ridges protecting the Intrusive and does not to join two headlands of sediment created by offshore waves cliff behind. fit in with the local 3.7.3 Landforms of deposition: Sand dunes . Soft Engineering Defences 3.7.7 Landforms of deposition: Saltmarsh

Beach Beaches built Cheap Develop in three types of Nourishment up with sand, so Beach for tourists. environment: waves have to Storms = need travel further replacing. - Sheltered areas where before eroding Offshore dredging deposition occurs. cliffs. damages seabed. - Where salt and freshwater meet. Marsh Low value areas Reduce flood risk 1) Large quantities of sand from constructive waves - Where there are no creation of the coast are Creates wildlife 2) Large tidal range, creating a large exposure of sand that can dry out at strong tides or left to flood and habitats. low tide currents to prevent erode naturally. Compensation for land. 3) Dominant onshore winds, to blow dried sand to the back of the beach. sediment deposition.