Coasts Flashcards
Igneous rock examples
Granite,basalt,dolarite
Metamorphic examples
Slate,schist,marble
Sedimentary examples
Sandstone,limestone,shale
Two types of rock that make up the earths crust
Bedrock/solid geology (e.g. granite)-main mass of rock that makes up crust
Superficial geology (e.g. Boulder clay/glacier till) laid down in last 2.5 million years.
Headland/bay example
Swanage bay and Ballard point or durlston head
Dunes/psammoseres: how is it formed
Very dynamic, loose sand blown inland by onshore winds,sand trapped by debris like rock and litter, then once established vegetation helps stabilise dune by succession, each stage is called a sere.
Dune stages with plants
Final stage: climatic climax stable balance with climate and soils (dynamic equilibrium)
Plant order: Lyme grass
Marrow grass
Lichens
Pine
Berm/embryo dune/white - pioneer species colonises environment , harsh and salty to one plants can tolerate, stabilises root system/binds and traps sediment e.g LYME GRASS
Foredune/yellow/blow out - deep roots bind dune together e.g. MARROW GRASS
Grey/dune slack and wasting dunes - amount of sand reduces inland, more plants marram dies out leads to humus leads to grey e.g LICHENS
Mature dunes - heath/woodlands adapt to tolerate salt e.g PINE
What are halophytes and xerophytes?
Halophytes - salt marsh, can tolerate salt water
Xerophytes - sand dune, can tolerate dry conditions
Salt marsh/Halosere
Plant order: Algae
Cordgrass
Marshgrass
Salt grass
Muddy,salty,low energy environments. Tidal conditions bring sediments in and out and rivers bring in silt and deposits it then particles stick together get heavy and sink (flocculation)
Plant succession: Algae/eel grass - colonise,pioneer,salty conditions,silt accumulation
Then conditions change as plants adapt to spend less time submerged(Cordgrass)
Vegetation forms thick mat (Marshgrass)
Area rises above tidal influence (Saltgrass)
What is eustatic Change and isostatic change?
Eustatic change: change in sea level due to volume of water(global change) e.g. ice melting or locked up from evaporation, thermal expansion
Isostatic change: local changes in sea level due to land rising or falling e.g. ice weight causes crust to sag, but when melt isostatic rebound occurs + accretion
Terms used to describe sea level rise and fall
Rise = marine transgression,coast drowned/submergent coast
Fall = marine regression, sea bed exposed/ emergent coast
Contemporary sea level change: milankovitch cycles
Eccentricity - where earth fluctuates between a near circular orbit and elliptical orbit.more sun energy when circular> thermal expansion.
Precession - like a spinning top>influences seasons
Tilt - shaking
Spit example (hook and double)
Hook: hurst castle spit
Double: Christchurch harbour
CASE STUDY:Christchurch bay
SE coastline exposed to destructive waves,Cliffs susceptible to slumping from rising sea levels groynes at heigistbury head starve sediment and brutal storms due to long fetch. 1 M ERODED PER YEAR
CASE STUDY: Sustainable management in the maldives
Rising sea levels, constructing artificial islands, unlikely to help whole population.
Risk: money spent on artificial islands to protect capital city Malé unlike to help other isolated islands, fishing overlooked in favour of tourism, MFF (protecting mangroves which are natural defence,evacuate people).
CASE STUDY: Storm surges in Bangladesh, Sidr 2007
Locations in paths of tropical cyclones are vulnerable to storm surges, low air pressure and stronger winds.
Causes: much of country is low lying river delta, melting water from Himalayas, storm surges meet river discharge from Ganges which increases flooding, tropical cyclones contribute to flooding, deforestation reduced coastal defence.
Impacts: 15000 DEATHS, 1.7 BILLION IN ECONOMIC LOSSES,however improved warning systems lowered death toll from previous cyclones (130000), cyclone shelters, eroded farmland and caused migration.
CASE STUDY: North Sea storm surge 2013
A very deep depression very low air pressure and rising storm surge potential and strong onshore winds = WIND 140MPH ,5.8M STORM SURGE AND HIGH TIDES.
Impacts: Areas affected - Scotland, Germany etc.
Coastal flooding, Scotland rail network closed, 100,000 HOMES LOST POWER, 15 DEATHS, erosion, better forecast and evacuation and coastal defences reduced impacts.
CASE STUDY : Holderness
PART 1
Holderness is the area not individual coasts in East of England north of Grimsby. Towns located are flam borough, Bridlington and Hornsea.
Why? - Weak geology and destructive waves e.g. glacier till, hydraulic action and abrasion causes rotational slips and breaking of till and LSD.
Soft engineering- Kilnsea (retreat the line)
Includes flood banks that last for 20 years, largest business in Kilnsea has roll back scheme to move mobile homes inland, sea defences can’t help as spurn head would suffer.
Hard engineering- Bridlington/withernsea/Hornsea: Groynes, revetments,boulders and sea walls
Mappleton:1.9 MILLION POUNDS FOR 60000 TONNES OF GRANITE FOR REVETMENT at base of cliff, 2 GROYNES, protecting businesses and main road and cliff
Easington: 25% OF ENGLANDS FUEL, groynes and revetments holding the line for 50 YEARS.
CASE STUDY: Holderness
PART 2
Physical factors: Weather - winter storms produce stronger waves and higher sea levels, saturated cliffs, mass movement, lsd > less protection
Waves - destructive waves, long fetch, suspension, lsd formed spit (spurn head)
Geology - chalk=flamborough head more resistant, Boulder clay easily eroded.
Human factors: Human presence e.g. development of retirement homes, interfering with natural processes e.g. defences and global warming.
Decisions made in a holistic way(smp,cba)
Spurn head: estuary into a spit
Flamborough head: wave erosion cause cave et
Groynes at Hornsea starved mappleton.
