9352062
Description
Flashcards by Erin Vernon, updated more than 1 year ago
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Created by Erin Vernon
over 8 years ago
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| Question | Answer |
| What is a costal environment? | Open systems with a range of inputs, outputs, stores, flows, that combine to create distinctive landscapes. |
| What do coastal landscapes consist of? | Constantly changing assemblage of erosional and depositional landforms. |
| What are the 5 different zones of a coastline? | Backshore Foreshore Inshore Offshore Nearshore |
| What is Backshore? | Area between HWM and the landward limit of marine activity |
| What is Foreshore? | Area between HWM and LWM |
| What is foreshore the most important zone for? | Marine processes in times that are not influenced by marine activity |
| What is Inshore? | Area between the LWM and the point where the waves cease have any influence on the land beneath them. |
| What is Offshore? | Area beyond the point where the waves cease to have impact on the land underneath them and in which activity is limited to deposition of sediment. |
| What is Nearshore? | Area extending seaward from the HWM to the area where the waves begin to break. |
| What does Nearshore include? | Swash zone, Surf zone, Breaker zone. |
| What is the swash zone? | Area where a turbulent layer of water washes up the beach following the breaking of a wave |
| What is the Surf zone? | Area between the point where waves break, forming a foamy, bubbly surface, and where the waves then move up the beach as wash. |
| What is the breaker zone? | Area where waves approaching the coastline begin to break, usually where the water depth is 5-10m |
| What are the inputs into a coastal system? | Energy from waves, winds, tides and sea currents Sediment Geology of the coastline Sea level change |
| What are the components within a coastal system? | Characteristics of erosional and depositional landforms |
| What are the Outputs of a coastal system? | Dissipation of wave energy Accumulation of sediment above the tidal limit Sediment removed beyond local sediment cells. |
| What is Erosion? | The wearing away of the earths surface by the mechanical action of processes of glaciers, wind, rivers, marine waves and wind. |
| What is Fetch? | Refers to the distance of open water over which a wind blows uninterrupted by major land obstacles. |
| What does the length of fetch help you determine? | The magnitude (size) and energy of the waves reaching the coast. |
| What is Mass Movement? | The movement of material downhill under the influence of gravity, but may also be assisted by rainfall. |
| What is Weathering? | The breakdown/decay of rock at/near the earths surface. |
| What are the 3 types of Sub- aerial Weathing? | Mechanical, Biological and Chemical weathering. |
| How are waves created? | By the transfer of energy from the wind blowing over the sea surface (referred to as frictional drag) |
| The energy acquired by waves depends on... (3) | Strength of wind, length of time it is blowing and the fetch. |
| What is meant by Prevailing wind direction? | A wind from the direction that is predominant or most usual at a particular place. |
| Wave characteristics include? | Wave height Wavelength Wave frequency |
| What is Wave height? | Difference between a wave crest (top of wave) and the neighbouring trough (bottom of wave). |
| What is Wavelength? (amplitude) | Distance between successive crests. |
| What is Wave frequency? (wave period) | Time for one wave to travel the distance of one wavelength, or the time between one crest and the following crest passing a fixed point. |
| What happens as the waves approach shallow water? | Friction with the seabed increases and the base of the wave begins to slow down. This Increases the wave height and steepness of the wave until the upper part plunges forward and the wave breaks onto the shore. |
| The rush of water up the beach after a wave break is known as... | Swash |
| Water receding back down the beach towards the sea is called... | Backwash |
| What are the characteristics of constructive waves? | Low wave height Long wavelength Low frequency (6-8mins) Swash more powerful than backwash so beach material is built up |
| What are the characteristics of destructive waves? | High wave height Steep form High frequency (10-14mins) More sediment removed than added Strong backwash as little forward movement of water Inhibits swash of next wave Pulls material back down the beach |
| Constructive waves build up the beach resulting in... | Steeper beach profile which encourages waves to be more destructive. |
| Destructive waves move material... | Back down the beach resulting in a reduced beach angle and encouraging more constructive waves. (Example of negative feedback) |
| Explain the Wave refraction process. | When waves approach a coastline that is not a regular shape, they are refracted and become increasingly parallel to the coastline. |
| What happens as each wave approaches the coast? (Wave refraction) | Tends to drag in the shallower water which meets the headland. |
| What does the wave dragging in the shallower water mean? | Increases wave height Increases wave steepness Shortens the wavelength |
| In wave refraction the part of the wave in deeper water... | Moves forward faster causing the wave to bend. Therefore the wave energy becomes concentrated on the headland causing greater erosion. |
| In wave refraction the low energy waves... | Spill onto the bay resulting in beach deposition. |
| What is meant by the term Currents? | Permanent or seasonal movement of surface water in the seas and oceans. |
| Name 3 types of current. | Longshore currents, Rip currents and Upwelling. |
| Why do Longshore currents occur? | As most waves do not hit the coastline head on but approach at an angle to the shoreline. |
| What do Longshore currents generate? | A flow of water running parallel to the shoreline . This moves water along the surf zone and transports sediment parallel to the shoreline. |
| What are Rip currents? | Strong currents moving away from the shoreline. |
| When do Rip currents develop? | When sea water is piled up along the coastline by incoming waves. Initially the current may run parallel to the coast before flowing out through the breaker zone. (Possibly at a headland or where the coast changes direction) - Hazardous to swimmers/small boats. |
| What is Upwelling? | The movement of cold water from deep in the ocean towards the surface. The more dense cold water replaces the warmer surface water and creates nutrient rich cold ocean currents. - form part of the global ocean circulation currents. |
| What is Longshore/Littoral drift? | Where waves approach the shore at an angle and swash and backwash then transport material along the coast in the direction of the prevailing wind and waves. |
| What is the definition of a tide? | The periodic rise and fall in the level of the sea in response to the gravitational pull of the sun and moon. |
| Why does the moon have a greater influence than the sun on tides? | It is nearer to the earth. |
| What effect does the moon have on tides? | The moon pulls water towards it creating high tide so there is a bulge on the opposite side of the earth. |
| In areas of the world between the two bulges the tide is at its... | Lowest. |
| As the moon orbits the earth... | The high tides follow it. |
| What happens twice in a lunar month? (Answer no1) | The moon and sun and the earth are in a straight line therefore the tide raising force is at its strongest. |
| What does the sun, moon and earth all being in line produce? | Highest monthly tidal range called SPRING TIDE. |
| What happens twice in a lunar month? (Answer no2) What does this produce? | The moon and the sun are positioned at 90° This alignment gives the lowest monthly tidal range called NEAP TIDES. |
| At times of Neap tides the high and low tides are.. (How far they range from the average) | 10-30% lower than the average. |
| What is the definition of a Tidal range? | The difference in the height of the sea water at high and low tide. |
| What do Tidal ranges determine? | The upper and lower limits of erosion and deposition and the amount of time each day that the littoral zone is exposed and open to sub-aerial weathering. |
| What are Tidal/storm surges? | Occasions when meteorological conditions give rise to strong winds which can produce much higher water levels than those at high tide. |
| Strong waves drive waves... | Ahead of the storm, pushing the sea water towards the coastline. |
| What is Coastal sediment budget? | The balance between sediment being added to and removed from the coastal system. That system being defined within each individual sediment cell. |
| What is a High energy coast? | A coastline where strong, steady prevailing winds create high energy waves and the rate of erosion is greater than the rate of deposition. |
| What is a Low energy coast? | A coastline were wave energy is low and the rate of deposition often exceeds the rate of erosion of sediment. |
| What are typical landforms at a Low energy coast? | Beaches Spits |
| What are typical landforms at a High energy coast? | Headlands Cliffs Wave cut platform |
| What is a Sediment cell? | A distinct area of coastline separated from other area by well-defined boundaries such as headlands and stretches of deep water. |
| Where does Coastal sediment come from? (5) | Streams/rivers flowing into the sea Estuaries Cliff erosion Offshore sand banks Material from a biological origin - including shells, coral fragments, skeletons of marine organisms. |
| Where do sediment movements occur? | Distinct areas or sediment cells within which inputs and outputs are balanced. |
| What type of system is a sediment cell? | Regarded as a closed system from which nothing is gained or lost. |
| What do the processes of coastal erosion control? | Control the level of the deficit as they remove material from the shoreline and if more sediment is removed than added then the coastline will recede. |
| What does calculating the sediment budget for a cell require? | The identification of all sediment sources and sinks and an estimation of the amount of sediment added and removed each year. |
| What is the definition of marine processes? | Operate upon a coastline that are connected with the sea such as waves, tides and Longshore drift. |
| What is the definition of sub-aerial processes? | Operate on the land but affect the shape of the coastline such as weathering, mass movement and run-off. |
| What are the 5 types of marine erosion? | Hydraulic action Abrasion Attrition Wave Quarrying Solution |
| What is Hydraulic action? | Impact on the rocks by the sheer force of the water itself. This can exert enormous pressure upon a rock surface thus weakening it. (can be called wave pounding) |
| What is Wave quarrying? | A breaking wave traps air as it hits a cliff face. The force of the water compresses air into any gap in the rock face creating enormous pressure within a joint. As the water pulls back there is an explosive effect of air under pressure being released. Over time this weakens the cliff. |
| What is Abrasion/corrasion? | The material the sea has picked up erodes the rock face by material like sand, shingle and boulders being hurled against the cliff face eroding it away. |
| What is Attrition? | The rocks carried by the sea hit into each other and slowly break down into smaller rounder pieces of rock. |
| What is Solution? (corrosion) | The dissolving of calcium based rocks due to the acidity of the sea. |
| What are the 6 factors that affect the rate of coastal erosion? | Wave steepness and breaking point Fetch Sea depth Coastal configuration Beach presence Human activity |
| How does human activity affect the rate of erosion? | People may remove protective materials from beaches, which may lead to more erosion. They may reduce erosion by the construction of sea defences. Sea defences can increase rates of erosion elsewhere on the same coastline |
| How does Sea depth affect the rate of erosion? | A steeply shelving sea bed at the coast will create higher and steeper waves. |
| How does Fetch affect the rate of erosion? | How far the wave has travelled determines how much energy has been generated in it. |
| How does Beach presence affect the rate of erosion? | Beaches absorb wave energy and can therefore provide protection against marine erosion. Steep, narrow beaches easily dissipate the energy from flatter waves. Flatter wider beaches spread out the incoming wave energy and are best at dissipating high and rapid energy inputs. |
| How does Coastal configuration affect the rate of erosion? | Headlands attract wave energy through refraction. |
| How does Wave steepness and breaking point affect the rate of erosion? | Steeper waves are high energy waves and have greater erosive power than low energy wave. |
| Why is the point at which the waves break important for the rate of erosion? | Waves that break at the foot of the cliff release more energy than those that break some distance from the shore. |
| What is Lithology? | The characteristics of rocks - especially resistance to erosion and premeability. |
| What is differential erosion? | Variation in the rates at which rocks wear away. |
| What is a discordant coastline? | The rocks run at right angles to the coast. |
| Where do the steepest cliffs tend to form? | In rocks that have horizontal strata or which dip gently inland. |
| What are the 4 types of marine transportation? | Traction Suspension Saltation Solution |
| What is Traction? | Large stone or boulders are rolled and slid along the seabed and beach by moving water. |
| What is Saltation? | Small stones bounce along the seabed and beach. As these particles land they in turn dislodge other particles upwards causing more saltation. |
| What is Suspension? | Very small particles of sand are carried along by moving water. It is carried but also picked up. |
| What is Solution? (transportation) | Dissolved materials are transported within the mass of moving water. |
| What happens to the movement of sediment after longshore drift? | Sediment moves in a zig-zag fashion down the coast. |
| Where does marine deposition often take place? | Where the waves are low energy or where rapid coastal erosion provides an abundant supply of material. |
| Name 4 situations where deposition occurs. | When sand and shingle accumulate faster than they are removed As waves slow following breaking As water pauses at the top of the swash before backwash begin When water percolates into the beach material as backwash takes sit back down the beach. |
| What is meant by Aeolian deposition? | Entrainment, transport and deposition of sediment by the wind |
| What is surface creep? | Process similar to traction where wind rolls or slides sand grains along the surface. |
| What are the two main headings of Sub-aerial processes? | Sub-aerial weathering and mass movement. |
| Sub aerial weathering includes processes that... | Break down the coastline, weaken the underlying rocks and allow sudden movements or erosion to happen more easily. |
| What are the 3 categories of sub-aerial weathering? | Biological Chemical Mechanical/Physical |
| What are Mechanical weathering processes? | Processes that occur at coasts depend on the nature of the climate. When the temperature is below freezing freeze thaw may occur. |
| Explain the process of Freeze thaw. | Water enters cracks in the rocks. As temperatures drop and remain below 0° the water freezes. As it freezes the water expands by almost 10%. Therefore it puts pressure on the gap in the rock. As the process repeats the crack widens and eventually pieces of rock break off. |
| What are Biological weathering processes? | Processes that lead to the breakdown of rocks by the action of vegetation and coastal organisms. |
| What is one example of Biological weathering? | Animals can weaken cliffs as they burrow or dig into them - such as rabbits. |
| What are Chemical weathering processes? | Processes are common on coasts as it occurs when rocks are exposed to air and moisture so chemical processes can breakdown the rocks. |
| What are examples of Chemical weathering? (5) | Acid rain Oxidation Hydration Hydrolysis Carbonation |
| What are the 5 types of mass movement? | Soil Creep Landslides Rockfalls Rotational slumping/slip Mudflows |
| What is the nature of mass movement experienced dependent on? | Level of cohesion within the sediment Height of slope Slope angle Grain size within sediment Temperature and level of saturation |
| What are Landslides? | Landslides occur on cliffs made from softer rocks or deposited material, which slip as a result of failure within when lubricated. (maybe following heavy rainfall) |
| What are rock falls? | Occur from cliffs undercut by the sea or on slopes affected by mechanical weathering like frost action. |
| What are Mudflows? | Heavy rain can cause large quantities of fine material to flow downhill. Here the soil becomes saturated and if excess water cannot percolate deeper into the ground surface layers become very fluid and flow downhill. |
| What is the nature of the flow in mudflows dependent on? | The level of saturation, type of sediment and slope angle. |
| What is rotational slip or slumping? | Where softer material overlies much more resistant materials. cliffs are subject to slumping. With excessive lubrication whole sections of the cliff face may move downwards with a slide plane that is concave producing a rotational movement. |
| What is Soil creep? | Occurs where there is very slow almost imperceptible, but continuous movement of individual soil particles downslope. |
| What may run off take the form of? | A stream emerging in a bay - taking with it large quantities of load during times of flood A stream cascading over a cliff excavating a V-shaped groove as it does so. Water that flows over a surface to reach a coastline. |
| What is a coastline? | The zone where the land meets the sea |
| What can coastlines either be? | Concordant or discordant Cliffed coast, flat coast, graded shoreline Emergent or submergent coastline. |
| Areas with alternating less or... | More resistant rocks are a common feature of many coastlines |
| What areas do erosional processes initially predominate in? | Areas with less resistant rock |
| What does this form? | Bays |
| What does this leave? | The more resistant rock protruding out to sea as headlands. |
| What then happens because of refraction? | The headlands then receive the highest energy waves and are more vulnerable to the forces of erosion than are the bays. |
| What waves do the bays experience? | Low energy waves that allow sediment to accumulate and form beaches. |
| What do these then act to? | Protect that part of the coast.. |
| What happens when geology runs parallel to the coast? | It is possible for marine processes to create headlands and bays |
| What happens when high and steep waves break at the foot of a cliff? | Their energy and erosive action is concentrated into a small area of the rock face |
| What then begins to happen? | Cliff begins to be undercut, forming a wave cut notch |
| What does further erosion do? | Increases stress on the cliff above and over time it will collapse |
| Cliff line tends to retreat and after... | Successive collapses a gently sloping relatively smooth wave-cut platform is formed at base of cliff |
| The platform continues to grow, what happens as it does? | Waves break further out to sea and have to travel across more platform before reaching the cliff line |
| What does this lead to? | Greater dissipation of wave energy, reducing rate or erosion and slowing down rate of growth of platform. |
| What are Geos, Caves, blowholes, arches, stacks and stumps? | Features are all independently observable on coastlines around the world, represent a sequence of events in erosion of a cliff or headland |
| Along a joint the sea will cut inland, widening the crack to for a what? | Narrow, steep sided inlet known as a geo |
| In other circumstances... | Cliff is undercut and cave is formed, usually from a combination of marine processes |
| What happens if erosion continues vertically upwards? | Is possible for cave to be extended to the top of the cliff to form a blowhole. |
| What is much more likely? | If cave is on side of a headland, is that is will extend backwards to meet another on the other side, due to refraction around the headland. |
| Eventually the conjoining of the caves will... | create a hole all the way through the headland called an arch |
| What happens as the cliff recedes? | Wave cut platform develops, arch will eventually collapse due to gravity following a combination of marine erosion from below aided by sub-aerial weathering weakening the arch |
| What does this leave? | Isolated portion of rock called a stack standing above the platform. |
| What happens over time? | Sea will exploit the wave cut notch at the base of the stack, leading to its collapse. |
| What may be left behind? | Small portion of wave cut platform called stump |
| Where do landforms of coastal deposition occur? | On coastlines where sand and shingle accumulate faster than they are removed. - where waves are low energy or where rapid coastal erosion provides abundant supply of material |
| Where are beaches found? | At the point where the land meets the sea and represents the accumulation if sediment deposited between spring and neap tides and the highest point reached by storm waves. |
| What type of beaches does sand tend to produce? | Beaches with a more gentle gradient because its small particle size means the sand becomes compact when wet and allows little peculation. |
| Most of the swash... | Therefore returns as backwash, little energy is lost to friction and material is carried down the beach. |
| What does this lead to? | The development of ridges and runnels in the sand at the LWM |
| What direction to these run? | Parallel to the shoreline and are broken by channels that drain water off the beach |
| Shingle can either make up the whole... | Or the upper parts of a beach |
| The larger the size of the material generally... | The steeper the gradient of the beach. |
| Why is this? | Because water rapidly percolates through shingle, so the backwash is somewhat limited in its ability to transport material back down the beach. |
| What does this, together with the uneven surface, mean? | Very little material is eroded from the beach |
| What happens at the back of the beach at spring tide? | Strong swash will create a storm beach |
| What is this? | A ridge composed of the biggest boulders thrown by the largest waves, above the usual tide mark. |
| What will be below this? | Series of ridges marking the successively lower tides as the cycle goes from spring to neap. |
| What are these beach ridges known as? | Berms and are built by constructive waves. |
| What are cusps? | Semi-circular shaped depressions which form when waves break directly onto the beach and swash and backwash are strong. |
| Where do they usually occur? | At the junction of the shingle and sandy beaches |
| What do the sides of the cusps channel? | Incoming swash into the centre of the embayment and this produces a stronger backwash in the central area which drags material down the beach, deepening the cusp |
| What develop below this? | Ripples |
| What are swash aligned beaches? | Oriented parallel to the incoming wave crests Experience minimal longshore drift Can be found on irregular coastlines |
| What are drift aligned beaches? | Oriented parallel to the direction of dominant longshore drift Considerable amounts of sediment transported long distances along them Initially develop where a section of the coastline is fairly regular/where the predominant wave direction is at an angle to the beach Can extend out from coastline if there is sudden change in the direction of the coastline |
| What is a spit? | An elongated, narrow ridge of land that has one end joined to the mainland and projects out into the sea or across an estuary |
| Where do these usually occur? | On drift aligned beaches |
| What is the formation of a spit? | Material is carried in the direction of the prevailing wind and maximum fetch by longshore drift There is then a build up of material, finer material is carried further into the deeper water of the estuary and as the water loses its capacity to transport it further it is deposited extending the spit into the estuary The end begins to curve as wave refraction carried material round into the more sheltered water |
| What does a simple classification of spits include? | Simple or compound spits |
| What are simple spits? | Either straight or recurved DO not have minor spits or recurved edges along their landward edge |
| What are compound spits? | Similar features to simple spits Have a number of recurved ridges or minor spits along their landward side |
| What could this be marking? | Position where they terminated in the past |
| What can occur as spits mature? | Sand dunes |
| How? | As deposited sand dried out and is blown to the landward side of the spit where it can accumulate and become stabilised by vegetation as species like marram grass get established |
| What happens as spits increase in size? | Large, more sheltered area develops between land and the spit. Low energy, gentle waves enter this area and deposit finer materials such as silt and clay. |
| What then happens as these build up? | Colonised by vegetation and become salt marshes |
| What is a Tombolo? | A spit that joins an island to the mainland |
| How is a bar formed? | If a spit develops across a bay where there is no strong flow of water from the landward side, it is possible for the sediment to reach across to the other side |
| However... | Some bars may simply be the result of he onshore migration of material from offshore as sea levels rose following the last ice age |
| What is an offshore bar? | Where a ridge of beach material that remains semi-submerged accumulates seaward of the breaker zone |
| What is a barrier beach/island? | Elongated bank of deposited sand or shingle lying parallel to the coastline but not submerged by incoming tides. Where the bank is high enough to allow sand dunes to develop it is known as a barrier island. |
| Where the sea and land interact there is a huge diversity of characteristic coastal landscapes including... | Bays Estuaries Beaches Deltas Dunes Mud flats and salt marshes |
| What are examples of a range of factors that have been important in producing the present coastal landscape features and continue to do so today? | Local tectonic plates Sea level change Climate change Changing ocean currents & wave regimes Natural disasters of events Changing sources,types,amount sediment Changing nature of human activity |
| What are coastal sand dunes? | Accumulations of sand shaped mounds by the wind |
| What do important inputs include? | A plentiful sand supply Strong onshore winds Large tidal range An obstacle to trap the sand Vegetation growth to encourage further growth |
| How is sand mostly transported? | Inland by process of saltation |
| How do sand dunes develop? | Sand may become trapped by obstacles at the back of the beach The first dunes to develop are known as embryo dunes - able to grow upwards through accumulating wind blown sand, stabilising in the surface - hummocky dunes are formed The long roots and underground shoots also help bind the sand together + plants add organic matter, aids water retention Upward growth of embryo dunes raises height to create dunes beyond reach of all highest storm tides , these are called foredunes Initially yellow because contain little organic matter but as vegetation cover increases, humus is added & dunes become more grey (heights of 20m) Gradually become fixed, an organic layer develops as other types of vegetation colonise. Dune slacks develop in places, depressions within the dunes where the water table is on our near the surface - conditions are often damp Behind yellow & grey dunes, supply of sand is gradually cut off giving smaller dune features - dune heath Possible to find blowouts within this system where wind has been funnelled through areas & has removed the sand |
| What else can cause blowouts? | Wildlife and human activity can often be a catalyst for the formation of blowouts |
| Where do mudflats only develop? | On sheltered shorelines that are not exposed to powerful waves. - often located in estuaries where rivers meet the sea or on landwards side of the spit. |
| What are mudflats? | Low lying areas of the shore that are submerged at high tide and are composed of silt and clay. |
| How do mudflats develop? | In estuaries where the flow of fresh water out of the river is slow and the sea water flows into the river mouth with each high tide and out with each low tide. Where saltwater flows into the estuary i brings fine sediments, it meets the equally slow moving river which is also carrying its own fine silts and clay. As they meet the fine particles settle out of suspension by the process of flocculation, where the individual clay particles aggregate together to form larger heavier particles that can sink into the bed. At low tide inter-tidal area of mud is exposed with water only left in permanent channels |
| What can happen over time to mudflats? | Can turn into salt marshes |
| What is the vegetation succession that develops is known as? | A halosere |
| How does this happen? | Low lying vegetation may begin to grow which slows the currents further so more uneven deposition Pioneers begin to colonise the area - able to tolerate the salt known as halophytes Pioneers gradually develop close vegetation over the mud allowing colonisation of other plants - form dense mat of vegetation up 15cm high - dead organic matter also helps to build the surface. As land rises above sea level rushes and reeds become established - lead to trees to complete succession. Now rarely covered by sea |
| What is eustatic change? | A global change in sea level resulting from an actual fall or rise in the sea level itself |
| What is Isostatic change? | Local changes in sea level resulting from the land rising or falling relative to the sea. |
| What is a fjord? | Former glacial valley drowned by rising sea levels |
| What is a ria? | Former river valley drowned by rising sea levels |
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