Geography - Coasts
- Created by: crwxox
- Created on: 23-01-17 19:49
What is the littoral zone?
THE AREA OF COASTLINE THAT EXTENDS FROM THE BACKSHORE ZONE, THAT IS RARELY INUNDATED OUT TO THE OFFSHORE AREA THAT ARE SUBMERGED
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What is the prevailing wind?
A WIND FROM THE DIRECTION THAT IS PREDOMINANT OR MOST USUAL AT A PARTICULAR PLACE OR SEASON
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What is swash?
THE RUSH OF SEAWATER UP THE BEACH AFTER THE BREAKING OF A WAVE
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What is backwash?
THE MOTION OF RECEDING WAVES
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What is a storm surge?
A RISING OF THE SEA AS A RESULT OF WIND AND ATMOSPHERIC PRESSURE CHANGES ASSOCIATED WITH A STORM
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What is a landform?
A NATURAL FEATURE OF THE EARTH’S SURFACE
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What is erosion?
GRADUAL DESTRUCTION OR DIMINUTION OF SOMETHING
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What is weathering?
THE WEARING AWAY OF SOMETHING BY LONG EXPOSURE TO THE ATMOSPHERE
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What is chemical weathering?
THE EROSION OF ROCKS CAUSED BY CHEMICAL REACTIONS
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What is mechanical weathering?
WEATHERING WITHOUT ANY CHANGE IN THE CHEMICAL COMPOSITION
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What is biological weathering?
THE WEAKENING AND SUBSEQUENT DISINTEGRATION OF ROCK BY PLANTS, ANIMALS AND MICROBES
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What are marine processes?
EROSION BY WATER
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What is eustatic change?
WHEN THE SEA LEVEL CHANGES DUE TO AN ALTERATION IN THE VOLUME OF WATER
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What is isostatic change?
EQUILIBRIUM IN THE EARTH’S CRUST IN WHICH AN ELEVATED PART IN ONE AREA IS COUNTERBALANCED BY A DEPRESSED PART IN ANOTHER
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What are sub-aerial processes?
WEATHERING THAT HAPPENS TO THE COASTLINE ABOVE SEA LEVEL
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What is percolation?
WHERE WATER MOVES DOWNWARDS THROUGH THE SOIL
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What is lithology?
A DESCRIPTION OF A ROCKS PHYSICAL CHARACTERISTICS
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What is a bay?
A BODY OF WATER CONNECTED TO AN OCEAN OR LAKE FOUND ON DISCORDANT COASTLINES
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What is a headland?
A SECTION OF LAND JUTTING OUT INTO THE SEA FOUND ON DISCORDANT COASTLINES
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What is a promontory?
A HIGH RIDGE OF LAND OR ROCK JUTTING OUT INTO A BODY OF WATER
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What is a landslide?
THE MOVEMENT OF ROCK, DEBRIS OR EARTH DOWN A SLOPE CAUSED BY RAIN, EARTHQUAKES, VOLCANOES OR OTHER FACTORS THAT MAKE THE SLOPE UNSTABLE
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What is a tombolo?
A DEPOSITION LANDFORM IN WHICH AN ISLAND IS ATTATCHED TO THE MAINLAND BY A SPIT OR BAR
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What is a sediment cell?
SEDIMENT MOVED ALONG THE COAST BY LONGSHORE DRIFT APPEARS TO FORM PART OF A CIRCULAR CELL WHICH LEADS TO IT EVENTUALLY RETURNING UPDRIFT. DREDGING OF OFFSHORE SHINGLE BANKS CAN THUS CONTRIBUTE TO BEACH DEPLETION
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What is a sediment budget?
A COASTAL MANAGEMENT TOOL USED TO ANALYZE AND DESCRIBE THE DIFFERENT SEDIMENT INPUTS AND OUTPUTS ON THE COAST, WHICH IS USED TO PREDICT MORPHOLOGICAL CHANGE IN A COASTLINE OVER TIME
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What is negative feedback?
WHEN PERFORMING AN ACTION CAUSES FEWER PERFORMANCES OF THE ACTION
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What is positive feedback?
WHEN PERFORMING AN ACTION CAUSES MORE PERFORMANCES OF THE ACTION
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What are submergent coastlines?
STRETCHES OF COAST THAT HAVE BEEN INUNDATED BY THE SEA DUE TO A RELATIVE RISE IN SEA LEVELS
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What are emergent coastlines?
STRETCHES OF COAST THAT HAVE BEEN EXPOSED BY THE SEA DUE TO A RELATIVE FALL IN SEA LEVELS
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What are estuarine coastlines?
A PARTIALLY ENCLOSED OCASTAL BODY OF BRACKISH WATER WITH ONE OR MORE REVIERS OR STREAMS FLOWING INTO IT AND WITH A FREE CONNECTION TO THE OPEN SEA
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What is DEFRA?
DEPARTMENT FOR ENVIRONMENT, FOOD AND RURAL AFFAIRS
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What is a shoreline management plan?
A LARGE SCALE REPORT, ASSESSING THE RISKS ASSOCIATED WITH COASTAL PROCESSES
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What is integrated coastal zone management?
A PROCESS FOR THE MANAGEMENT OF THE COAST USING AN INTEGRATED APPROACH, REGARDING ALL ASPECTS OF THE COASTAL ZONE, INCLUDING GEOGRAPHICAL AND POLITICAL BOUNDARIES, IN AN ATTEMPT TO ACHIEVE SUSTAINABILITY
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What is managed retreat?
ALLOWING AN AREA THAT WAS NOT PREVIOUSLY EXPOSED TO FLOODING BY THE SEA TO BECOME FLOODED BY REMOVING COASTAL PROTECTION
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What is cost-benefit analysis?
A PROCESS WHEREBY THE BENEFITS OF A GIVEN SITUATION ARE SUMMED, AND THEN THE COSTS ASSOCIATED WITH TAKING THAT ACTION ARE SUBTRACTED
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What is hard engineering?
CONTROLLED DISRUPTION OF NATURAL PROCESSES BY USING MAN-MADE STRUCTURES
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What are sea walls?
A STRUCTURE SEPARATING LAND AND WATER AREAS TO PREVENT COASTAL EROSION
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What are groynes?
A RIGID HYDRAULIC STRUCTURE BUILT FROM AN OCEAN SHORE THE INTERRUPTS WATER FLOW AND LIMITS THE MOVVEMENT OF SEDIMENT
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What is cliff drainage?
INSERTING DRAINAGE PIPES WITHIN A CLIFF TO REMOVE EXCESS WATER
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What is rock bund?
THE EMBANKMENT BUILT ABOVE THE LEVEL OF THE FIELD BEHIND TO IMPOUND WATER ON THE FIELD DURING GROWING SEASON
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What is rock armour?
PLACING LARGE BOULDERS IN FRONT OF A CLIFF OR SEA WALL TO ABSORB THE ENERGY OF WAVES
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What are gabions?
A CAGE FILLED WITH ROCKS, CONCRETE OR SOIL TO PROVIDE PROTECTION FROM BACKSHORE EROSION BY ABSORBING WAVE ENERGY
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What are revetments?
WOODEN, STEEL OR CONCRETE FENCE-LIKE STRUCTURES THAT ALLOW SEA WATER AND SEDIMENT TO PASS THROUGH, BUT ABSORB WAVE ENERGY
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What are offshore bars?
ELONGATED RIDGES AND MOUNDS OF SAND OR GRAVEL DEPOSITED BEYOND A SHORELINE BY CURRENTS AND WAVES
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What is the promontory effect?
WHEN PROTECTED AREAS BEGIN TO PROTRUDE AS SURROUNDING AREAS ERODE
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What is soft engineering?
WORKING WITH NATURE BY USING NATURAL MATERIALS OR ALLOWING NATURE TO TAKE BACK AREAS
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What is beach replenishment?
THE PROCESS OF DUMPING OR PUMPING SAND FROM ELSEWHERE ONTO AN ERODING SHORELINE TO CREATE A NEW BEACH OR TO WIDEN THE EXISTING BEACH
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What is beach reprofiling?
THE DIRECT TRANSFER OF MATERIAL FROM THE LOWER TO THE UPPER BEACH
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What is beach recycling?
THE MECHANICAL SHIFTING OF SAND, SHINGLE AND BOULDERS FROM AN AREA OF ACCRETION TO AN AREA OF EROSION
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What is a habitat?
THE AREA OR NATURAL ENVIRONMENT IN WHICH AN ORGANISM OR POPULATION NORMALLY LIVES
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What is ecology?
THE BRANCH OF SCIENCE THAT EXAMINES THE RELATIONSHIPS ORGANISMS HAVE TO EACH OTHER AND THEIR ENVIRONMENT
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What is realignment?
THE DELIBERATE PROCESS OF ALTERING FLOOD DEFENCES TO ALLOW FLOODING OF A PRESENTLY DEFENDED AREA
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What is earth bund?
AN EMBANKMENT TO HOLD BACK WATER MADE OF EARTH
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What is coastal squeeze?
WHEN COASTAL HABITATS ARE TRAPPED BETWEEN A FIXED LANDWARD BOUNDARY FOR EXAMPLE A SEA WALL AND RISING SEA LEVELS
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What is reclamation?
THE PROCESS OF CREATING NEW LAND FROM OCEAN, RIVERBEDS, OR LAKE BEDS
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What is the growth pole?
THE CONCENTRATION OF HIGHLY INNOVATIVE AND TECHNICALLY ADVANCED INDUSTRIES THAT STIMULATE ECONOMIC DEVELOPMENT IN INDUSTRIES
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What are TNCs?
COMPANIES THAT OPERATE IN SEVERAL COUNTRIES
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What is eurotrophication?
THE PROCESS BY WHICH A BODY OF WATER BECOMES ENRICHED IN DISSOLVED NUTRIENTS THAT STIMULATE THE GROWTH OF AQUATIC PLANT LIFE USUALLY RESULTING IN THE DEPLETION OF DISSOLVED OXYGEN
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Describe the offshore zone
1. Permanently submerged 2. sediment only affected by storm waves which have lower wave bases
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Describe the near shore zone
1. Between high and low tide 2. Wet/damp most of the time
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Describe the back shore zone
1. Between foreshore and coastline 2. Only exposed to waves in extreme events
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Give 2 features found at submergent coastlines
Fjords and drowned river valleys
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Give 2 features found at emergent coastlines
Raised beaches and wave cut platforms
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Give two causes and two impacts of cliff collapse
C: global warming C: construction I: deaths/injuries I: Air pollution from vehicles clearing up debris
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Give one cause and two impacts of sea level change
C: global warming I: homes threatened I: habitats destroyed
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Describe 2 long term processes that determine the coastline
Geology: Determines what rocks make up the coast and therefore the shape of the coast as some eroded more easily than others. Sea level: Increase or decrease in sea levels create different coastlines due to isostatic or eustatic change
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Describe 1 short term prices that determines the coastline
Inputs from rivers, waves and tides: sediment transported creates coastal features. Waves also erode sediment, further changing the coastline.
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What are the two main types of coast?
Rocky and coastal plains
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Describe three features of a rocky coastline
High energy environment, resistant geology and subaerial processes evident
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Describe three features of a coastal plain
Low relief, high supply of sediment and low energy environment
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Describe 2 features of waves found at low-energy/high-energy coastlines
Constructive and short fetches/ destructive and long fetches
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Name a process that occurs at low-energy/ high-energy coastlines
Deposition/ erosion
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Name three landforms found at low-energy/ high-energy coastlines
beaches and spits/ cliffs and arches
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Give an example of a low-energy/ high-energy coastline
Mediterranean sea/ atlantic coast of Scotland
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Describe a concordant coastline
Occurs where layers of differing rock types fold into ridges that run parallel to the coast
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Describe a discordant coastline
Occurs where bands of different rock types run perpendicular to the coast. The differing resistance to erosion leads to the formation of headlands and bays
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Describe a dalmation coastline
Formed where the geology creates valleys parallel to the coast so when sea level rises, a series of islands remain.
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Describe a half coastline
Lagoons enclosed by long spits of sand parallel to the low coast
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How are headlands and bays formed
1. Caused by differential erosion, found in areas of alternating resistance. 2. Bays are formed at softer rock. 3. Headlands formed where there is harder rock
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Give two background facts on the Pembrokshire coast
1. Became a national park in 1952. 2. 40% of coastline is a SSSI
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What rock type is predominantly found there?
Sedimentary
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Name three factors that shape the Pembrokshire coast
1. Atlantic weather systems cause particularly large and strong waves 2. These waves cause marine erosion 3. West Pembrokshire is mainly discordant, creating headlands e.g. St Davids and bays e.g. St. Brides
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What feature of a cliff profile can make it more stable?
Horizontal bedding planes
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What features of a cliff profile can make it very vulnerable?
A low angle seaward dip and joints formed by weathering
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What is a dip?
Tilted layers of sedimentary rocks folded by tectonic processes
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What is a syncline?
Concaved U shapes
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What is an anticline?
A shaped folds
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What is a fault?
A break in a layer of rock caused by tectonic movement, often contributing to the creation of caves
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What is a fold?
Layers of rock that are bent or curved as a result of tectonic heating and bending
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What is a joint?
A natural break in a layer of rock often changing to another rock type
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What are fissures?
Small cracks that erosion can take advantage of
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Name three processes by which waves shape the coast
Erosion, transportation and deposition
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How are waves created?
Friction between wind and water transfers energy to the waves. Force of the wind creates ripples which form waves.
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Describe 4 features of destructive waves
1. Crests move forwards and downwards 2. Circular movement 3. Stronger backwash than swash 4. Can create a berm
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Describe 4 features of constructive waves
1. Nearshore depths are shallow, gently sloping beaches 2. Swash more powerful than backwash 3. Sediment moved up the beach widening it 4. Waves less frequent
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What are cusps?
Semi-circular depressions formed by a collection of waves reaching the same place
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What five factors determine the effectiveness of erosional processes?
1. Type of wave 2. Size of wave 3. Level of tide 4. Shape of the coastline 5. Lithology
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Describe hydraulic action
Air becomes trapped in joints and cracks. When a wave breaks the air is compressed, weakening the cliff
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Describe corrosion
Acids contained in sea water will dissolve some types of rock such as chalk or limestone
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Describe abrasion
Bits of rock and sand in waves grind down cliff surfaces like sandpaper
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Describe attrition
Waves smash rocks and pebbles on the shore into each other and they break and become smoother
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Which two erosion processes form caves?
Hydraulic action and abrasion
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Describe how features of coastal erosion are created
1. At a headland waves are refracted so the full energy of erosion is concentrated at weak points 2. Caves are formed first, which meet from opposite sides to form a tunnel 3. Eventually the arch collapses, leaving a stack 5. Eroded into a stump
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What moves sediment up and down a beach?
Waves
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What is the main process of transportation?
Long shore drift
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What determines the direction of LSD?
The dominant wind direction
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At what angle of the wind to the coast is LSD strongest?
30 degrees
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What can reverse the direction of LSD?
Headlands causing wave refraction
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Describe the movement of long shore drift
1. Swash moves sediments obliquely up beach at same angle as the approaching wave 2. Backwash moves sediment back down beach at 90 degrees due to gravity 3. Sediment moves along the beach in a zigzag until it meets an obstacle e.g. headland
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Describe the formation of offshore bars
1. When the waves approach a gently sloping coast, friction between the waves and sea bed cause the waves to break away from the coast 2. Over time, more material builds up parallel to the coast forming an offshore bar
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Describe the formation of barrier beaches
1. Formed where spits are joined to the mainland at both ends, trapping water behind in a lagoon 2. There must be a supply of sand, waves with sufficient energy to move sand, and rising sea levels
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Name a use and example of a barrier beach
Built on e.g. Miami beach
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What is Chesil Beach?
An 18 mile long, 200m wide, 18m high tom bolo
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Describe how Chesil Beach was formed
Rising sea levels caused erosion of deposits and waves drove the material east towards the mainland
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How is the beach changing over time?
It is moving east by 15cm every year
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What 3 conditions allow a spit to be formed?
1. Dominant LSD direction 2. Form across a gap in the coastline 3. Plenty of sediment from erosional and mass movement processes
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What grows behind spits?
Salt tolerant vegetation, forming mudflats and salt marshes
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What can form on the end of a spit due to tides, waves and river currents?
A hook, or recurved spit
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How are double spits formed?
Form when LSD advances from different directions due to local variation in wave directions caused by wave refraction around a headland
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Why don't they join?
Strong currents flowing into the sea, preventing deposition of coastal material across the estuary
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Describe the formation of tombolos
1. As waves near an island they are slowed by the shallow waves surrounding it 2. These waves bend around the island as they approach
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Describe the formation of cuspate forelands
Triangular beaches formed due to longshore drift moving sediment in opposing directions
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Describe 5 features of the sediment cell concept
1. Erosion, transportation and deposition operate in the sediment cell 2. Has sources, transfers and sinks 3. Each cell is a closed system 4. Sediment gained and lost can be measured in a sediment budget 5. Can be used to measure coastal change
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Give three examples of human activity that can interfere with the budget
Groynes, jetties and harbours
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Give three examples of sources of sediment within sediment cells
Cliff erosion, eroding depositional features, offshore bars
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Give three examples of transfers of sediment within a sediment cell
Longshore drift, currents and saltation
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Give three examples of sinks/stores of sediment cells
Estuaries, dredging and beaches
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What is the difference between weathering and erosion?
Weathering occurs over a longer time scale than erosion
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What are the three types of weathering?
Mechanical, biological and chemical
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Name the five main types of weathering within these categories? (FSOSB)
Frost shattering, salt crystallisation, oxidation, seaweed acids, boring molluscs
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Describe how frost shattering works and the effects that it has
1. Only found on coasts in a climate where the temperature changes above and below zero 2. Water seeps into cracks and expands when frozen 3. angular cliff face created
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Describe how salt crystallisation works and the effects that it has
1. Sodium and magnesium salt compounds are left behind by waves 2. Salt crystals grow and force rock apart 3. angular rock fragments loosened and rack faces crumble away
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Describe how oxidation works and the effects that it has
1. Oxygen combines with iron-based minerals in a rock, causing a chemical breakdown of the minerals 2. Rock minerals no longer bonded together so the rock crumbles
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Describe how seaweed acid works and the effects that it has
1. Some seaweed cells contain sulphuric acid and dissolve rock minerals 2. rock minerals will no longer be bonded together and parts of a rock will crumble
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Describe how boring molluscs work and the effect that they have
1. Marine molluscs love on coastal rock, scraping away at the rock for food 2. Holes provide weak points for the weathering processes to act
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Give three examples of where mass movement is seen
Landslides, mudslides and avalanches
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How does gravity cause mass movement?
It pulls ups material that has become unstable due to waves undercutting or rain entering rocks and forcing apart
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What determines the type of mass movement?
Water content
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What determines stability?
Slope angle
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Describe how weathering is linked to the sediment cell model
1. Weathering supplies rock fragments and sand to the sediment cell 2. this sediment is then moved around the cell by transportation 3. sediment may then be deposited by a constructive wave, but then eroded again by destructive waves
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How can humans control the movement of sediment?
Coastal protection techniques
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Give three ways that weathering influences rates of coastal recession
1. Fluctuations in temperature will increase or decrease frost shattering, affecting the rate of recession 2. higher waves during stormier weather will deposit salt crystals further up the cliff face, increasing salt crystallisation and the rate
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Describe rock falls and talus slopes
1. rock fragments fall to base and form talus or scree scopes 2. have large boulders at core and smaller material on top 3. slope angle between 34 and 40 degrees 4. Wave processes gradually reduce it in size
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Describe block falls
1. Large blocks of rock loosen and falls 2. 45 degree angle 3. rock moves down the glide plane to the impact point where debris from earlier slides is found
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Describe rotational slumping
1. Section of cliff remains intact as it moves down cliff along a curved slip plane 2. leaves a crescent shaped rotational scar 3. vegetation layer is usually intact on top of slump
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Describe a mudflow
This is where saturated soil and weak rock flows down a slope and produces a lobe - sometimes called a solifluction lobe.
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Describe the location, geology and mass movement occurring in Black Ven, Dorset
1. Between Charmouth and Lyme Regis 2. Porous limestone and clay 3. Mudslides constantly bring new material to base of the cliff
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Describe the location, geology and mass movement occurring in Dunwich, Suffolk
1. Small village on Suffolk Coast which used to be a port 2. Soft rock like clay 3. Marine erosion caused 7m of coastline to be lost in a storm lasting only a few days
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Describe the location, geology and mass movement occurring in Overstrand, Norfolk
1. North coast of Norfolk, very wealthy 2. Chalk 3. Marine erosion makes it prone to periodic slope failures and increased recession
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How does an ice age influence sea level?
Ice age = lower sea levels
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What period is the world currently in?
Interglacial period
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What are sea levels influenced by?
Eustatic, isostatic and tectonic change
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Describe the three Milankovitch cycles
1. AXIAL PRECESSION - the angle of tilt on earth's axis change over a 41,000 year cycle, causing different amounts of sunlight to reach the poles 2. ECCENTRICITY - Earth's orbit around the sun varies between a sphere and an ellipse. Less sun reaches
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Describe the effect of eustatic changes
1. During the ice age, lots of water was stored in ice 2. The UK was joined to Europe by ice 3. When the ice age ended, sea levels rose by 150m
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Describe the effect of isostatic changes
1. Ice is heavy and compresses land masses during ice ages 2. Land far away from the ice tilts upwards, once the ice starts to melt it readjusts 3. At the moment Scotland is rising and southern england is sinking
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How do tectonic processes cause sea level changes
1. Two plates colliding causes continental shelves to be pushed upwards e.g. Kerala, India 2. Other areas may sink e.g. Bakol-Vinadol, Croatia
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Other cards in this set
Card 2
Front
What is the prevailing wind?
Back
A WIND FROM THE DIRECTION THAT IS PREDOMINANT OR MOST USUAL AT A PARTICULAR PLACE OR SEASON
Card 3
Front
What is swash?
Back
Card 4
Front
What is backwash?
Back
Card 5
Front
What is a storm surge?
Back
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