coastal landscapes key notes Flashcards
what is the littoral zone
the wider coastal zone including adjacent land areas and shallow parts of the sea
exposed to air at full tide and underwater at high tide
what are the 4 litoral zones
backshore
- usually above the influence of waves
forshore
- inter tidal or surf zone
nearshore
- breaker zone
offshore
-beyond influence of waves
what are the inputs into coastal systems
- marine (waves)
-atmospheric ( weather) - land (rock)
- people
what are the main processes in coastal landscapes
- weathering
- mass movement
- erosion
- transport
- deposition
what are the main outputs in coastal landscapes
- erosional landforms
- depositional landforms
- different types of coast
what are coasts classified based on
- geology- rocky, sandy, discordant, concordant
- energy- high or low
-balance- between erosion and deposition - sea level- emergent or submergent
what are the features of a high energy coastline
- powerful waves
- rate of erosion is higher that deposition
- eg cornwall and north west scotland
- headlands, cliffs, shoreline platforms
what are the features of low energy coastlines
- less powerful waves
- deposition higher than erosion
- eg lincolnshire and northumberland
- spits , beaches and coastal plains
what are concordant coasts
where type of rock runs parallel to the coast
- eg south dorset
what are discordant coasts
- type of rock runs perpendicular to the coast
- eg East dorset
what are the features of a submergent coast
- have been flooded due to rise in sea levels
- eustatic seal level change
- dalmatian coasts
- haff coasts - long spits
what are the features of emergent coasts
- formed when water level has fallen or land has risen
- isostatic change
- rocky coastline with cliffs and platforms
- west coast of usa
what is coastal recession
coastal erosion
what are joints
fractures caused by contraction from sediment drying out or earth moving
what are strata
layers of rock
what is the dip of a rock
the angle at which the rock layers lie
what is lithology
physical characteristics of rocks
what is morphology
shape and form of coastal landscapes
what are bedding planes
natural breaks in strata
what are folds
formed by pressure during tectonic activity makes rock crumble
what are faults
when stress or pressure causes faults to slip or move
what are sedimentery, metamorphic and igneous rocks and how are they made
SEDIMENTARY
- created by build up of sediment over millions of years on bottom of ocean
- compacted by own weight
- sandstone and limestone
METAMORPHIC
- created from sedimentary and igneous that are subjected to extreme heat and pressure
- usually through subduction
- slate and marble
IGNEOUS
- volcanic activity it is formed from cooled magma
- granite and basalt
what is the geology of the uk
- SE is generally made from softer rock like clay and chalk
- SW is harder rock like basalt
- SW- cornwall faces bad weather but withstands erosion as made from igneous basalt, old sedimentary and slates which are all resistant
- SE made from younger weaker geology
what is the MOhs hardness scale
- relative hardness of rock is measured using scale that looks at what other materials could scratch it
- eg diamond at top and calcite near bottom
what are the four types of dip and what are characterisatics of each
HORIZONTAL DIP
- vertical profile with notches reflecting strata make it more easily eroded
- weaker strata at bottom cause top to topple eventually
SEAWARD DIP HIGH ANGLE
- sloping low angle profule with one rock layer facing sea
- vulnerable rock slides down slope
SEAWARD DIP LOW ANGLE
-profile may exceed 90 degrees producing areas of overhanding rock very vulnerable to rock falls
LANDWARD DIP
-steep profiles of 70-80 degrees
- produces a stable cliff with reduced rock falls
what are the erosion rates of igneous, sedimentary and metamorphic rock
igneous- very slow
- interlocking crystals make strong and hard
- few joints so limited points of weakness
metamorphic- slow
- crystalline are resistant to erosion
- foliation- where crystals all in one direction so weaker
sedimentary- moderate to fast
- age of sedimentary plays key role
- fractured rock more vulnerable
what rock type is cornwall made from
made from mainly basalt- igneous resistant rock
what rock type is the holderness coast made from
boulder clay and challk- super fast eroding
what is vegetations role in stopping erosion
- roots bind sediment
- plants in sediment cells provide protective layer from water
- protect sediment from wind
what are halophytes and xerophytes
H- can tolerate salt water
X- can tolerate dry conditions
what is plant succession
how a group of plants change over time
what is the pioneer species and what is climax vegetation
pioneer- first to grow
climax veg- new ecosystem are in equilibrium with the environment and np new species
what is the halosphere
plant growth in salty water
what is psammosere
- plant growth on sand
what are the different dunes in order and what are some features of each
EMBRUYO AND FORE DUNES
- sea weed
- sand building up
alkaline sand
- scattered plants that thrive being burried in sand
YELLOW DUNES
- continually blown away and replenished
- reduced wind speed
- top of dunes above high tide level
- salt tolerant plants that thrive being burried and deep roots
GREY DUNES
- incr humus content
- sand no longer accumulating
- many plants now coexisting
DUNE SLACK
- damp low lying hollows
- high water table in winter
- soil acidic
- moisture loving plants
WOODLAND
- acidic soil and incr organic matter
- nutrient rich
- shelter developed
what does wave size depend on
- strength of wind
- duration the wind blows for
- water depth
- wave fetch
what are constructive and destructive waves
c
- less than 1 m wave height
- wave length is low
- strong swash weak backwash
- creates wide flat coast plain
D
- more than 1m wave height
- frequency is high
- weak swash and strong backwash
- creates thin steep beaches
what are the erosional processes and how does each one cause erosion
HYDRAULIC ACTION- force of waves pushes air into cracks of rock
ABRASION - loose pebbles and sediment in water thrown against rock
ATTRITION- pebbles crash into each other
CORROSION- salt creates weak acid that slowly breaks down rock
what are the types of transportation and how do they work
TRACTION - sediment rolls along bottom
SALTATION - sediment bounces along
SUSPENSION - sediment carried in the water column
SOLUTION - dissolved material carried as a solution
what is longshore drift
- waves approach beach as an angle
- as wave moves, material is carried up beach at an angle
- backwash pulls material down beach at right angle to short
what are spits
- long narrow feature that extends from land to sea
- made from sand or shingle
- sand is moved along the coast by longshore drift
-when coast suddenly changes direction then sediment will begin to build up - eg farewell spit in new zealand
what are beaches and how are they made (what are the two types)
- commonly found in bays
- wave refraction creates low energy environment
- leads to deposition
DRIFT ALIGHNED BEACH - where waves break at an angle to coast and swash is at angle but backwash is perpendicular
SWASH ALIGHNED BEACH- swash and backwash move material up and down the beach
- beaches are curved
what are offshore bars
- submerged ridges of sand
- created by waves offshore
- destructive removes sediment and deposit offshore as bars
what are tombolos
- a beach or ridge of sand that has formed between islands and mainland
- deposition occurs where waves lose energy
what are bars
- where beach or spit extends across a bay
- joins two headlands up
- eg start bay in devon- 9km bar
- can trap water behind and form a lagoon
what are sediment cells
- sediment moves in sediment cells
- within each cell. moves between beach, cliffs and sea through processes
- any action that takes place in one part affects other parts
- cell operates between physical barriers
- have sources , transfers and sinks
what is sediment budget
sediment available in cell
what are subaerial processes
land based processes that alter shape of coast
what are the three types of mechanical weathering and how do they work
FREEZE THAW- this occurs when water freezes in cold weather. expands and causes cracks to widen
SALT WEATHERING- salt water evapourates and leaves salt crystals which grow and stresses rock.
WETTING AND DRYING- frequent cycles and expand and contract rock, causing them to crack
what are the 3 types of chemical weathering
CARBONATION - affects limestone due to rainfall
HYDROLYSIS- igneous and metamorphic rocks with water
OXIDATION- sandstone and addition of oxygen
what are the 3 types of biological weathering
PLANT ROOTS - grow into small cracks and break apart
ROCK BORING - clams bore into rock face and seccrete chemicals
ANIMALS - digg burrows into cliffs and cause to break
what are the different types of mass movement and how do they happen
FALL- where blocks of rock can be dislodged by hydraulic action
TOPPLE- rock strata have steep seaward dip leads to instability and topples seaward
TRANSLATIONAL SLIDE- low angle sea dip material tends to slide down slope towards the sea
ROTATIONAL SLIDE- movement can occur along curved surface and material slowly rotates downslope
FLOW- common in weak rock and flow downslope when saturated heavy rainfall
what is glacial maximum
means point where ice reached during ice age
what are two emergent coastal features and what do they consist of
RAISED BEACHES- areas of former wave cut platforms and their beaches are at higher level than the sea level
RELICT CLIFF- an old or previous cliff displaying features such as calves arches and stacks
what are three submergent coastal features and what do they consist of
RIAS- drowned river valley, flood river valleys leaving only high land visible
FJORDS- drowned glacial valleys where u shaped valleys left are submerged
DALMATION COASTS- where valleys are flooded and tops of valleys remain above surface, appear to be series of islands
what are storm surges
changes in sea level caused by intense low pressure systems and high wind speed
what challenges does climate change cause in coastal areas
- incr temp causing rising sea levels and more flood risk
- incr incidence of storms and flooding
- IPCC- major scientific body responsible for predicting and researching changes in climate say that :
- very likely that sea level will rise in more than 95% of areas
- very likely that global mean sea rise will continue for centuries
- hurricanes more intense
- windspeed will be 2-11% stronger
- rainfall will increase by 20%
what are some soft engeneering techniques and what are positives and negatives
BEACH NOURISHMENT- sand pumped to replace loss
- natural looking
- expensive and needs redoing
eg hornsea
SAND DUNE REGENERATION- action to build up sand dunes
- natural looking
- expensive and needs redoing
BEACH REPROFILING- movement of sediment from one area to another
- natural looking
- takes away from other areas causing more erosion here
ZONE MANAGEMENT- withdrawal of planning permission
- cost effective
- unpopular with residents involved
what is soft engineering
works with natural processes to manage erosion and looks nicer and positive public opinion
what is hard engineering
building structures that prevent erosion along the coast
tend to be more expensive
what are some hard engineering techniques and what are the positives and negatives
SEA WALLS - protect from sea erosion made from rocks or concrete
- works well
- costly and looks bad
eg hornsea
GABIONS- wire cages holding smaller rocks
- cheaper
-small scale solution
eg skipsea
GROYNES- rock or wooden structures that hold beach material
- repaired easily
- regular maintenance
- affect other areas
eg withernsea
what does tangible and intangible mean in terms of coastal management
T- where costs and benefits are known and can assign monetary value
I- costs may be difficult to assess
what are 4 coastal management strategies
- hold the line - maintaining current position
- advance the line- pushing coastline back out to sea
- managed retreat- allowing coast to retreat but in a managed way
- do nothing - letting nature take its course
what are some examples of how sustainable coastal management could be achieved
- monitoring coastal change
-educating communities - understanding why change is needed
- adapting to rising sea level
- creating alternative livlihoods
- managing flood and erosion risk
who is in charge of coastal management in the uk
DEFRA
what is cost benefit analysis
- tool used to help decide whether defening a coastline from erosion is worth it
- often controversial
- human and environmental costs are hard to quantify
who are some players in coastal management
- residents
- local council
- businesses owners
- local tax payers
- environmentalists
