Coasts Flashcards
3 types of weathering
Mechanical,chemical, biological
Chemical weathering
process of chemicals in rainwater making changes to the minerals in a rock.
Mechanical weathering
process of rocks crumbling due to rain, wind, or other atmospheric conditions.
biological weathering
living organisums break down rocks
Mass movements
the large movement of soil and rock down the slope of a hill or cliff
what causes mass movements
weathering erosion and gravity
3 types of mass movement
Slumps slides rockfalls
Slides
material moves down a slope in a straight line
slumps
material moves down slope at a curve
Rockfalls
material breaks and crumbles down a cliff
4 types of erosion
solution,abrasion,attrition,hydraulic action
abrasion
When pebbles grind along the river bank and bed in a sand-papering effect
attrition
When rocks that the river is carrying knock against each other. They break apart to become smaller and more rounded.
Hydraulic action
force of water crashing against the coastline causing material to be dislodged and carried away by the sea
soloution ( erosion)
When the water dissolves certain types of rocks
deposition
The laying down of sediment carried by the sea
when does deposition occur
when the swash is stronger than the backwash and is associated with constructive waves.
4 transport processes
traction.saltation,suspension,soloution
traction
large, heavy pebbles are rolled along the river bed.
Saltation
pebbles are bounced along the river bed,
Suspension
lighter sediment is suspended (carried) within the water
solution ( transport)
the transport of dissolved chemicals.
constructive waves
Deposit material onto coastlines because they have a strong swash and weak backwash
3 Features of constructive waves
-Not very tall
-Longer wavelength than destructive
-Low frequency
Destructive waves
Stronger backwash than swash meaning they drag more material away from coastline than whats desposited along the shore
In what areas are headlands and bays formed
Areas that have alternate areas of soft and hard rock facing the stea
What are concordant coastlines
Alternate layers of soft and hard rock
What are disconcordant coastlines
Coastlines have alternate layers of hard and soft rock at 90 degrees to the coast
How are wave cut platforms made
The sea attacks the base of the cliff between the high and low water mark.
A wave-cut notch is formed by erosional processes such as abrasion and hydraulic action - this is a dent in the cliff usually at the level of high tide.
As the notch increases in size, the cliff becomes unstable and collapses, leading to the retreat of the cliff face.
The backwash carries away the eroded material, leaving a wave-cut platform.
The process repeats. The cliff continues to retreat.
How are caves formed
Weaknesses in rocks like cracks are widened by erosional processes ( hydrochloric action and abrasion ) repeated erosion of the cracks causes them to be large enough to form caves
How are arches formed
Continued erosion deepens a cave until it breaks through the headland
How are stacks formed
When top of arch collapses due to gravity
How are spits formed
-Sharp bends in the coastline
-Longshore drift transports sand past the bend and desposits into the sea
-Strong winds curve end of the spit
-The sheltered area behind a spit is proctected from waves so can bevome mud slat or salt marsh
How is a bar formed
Sometimes a spit can grow across a bay, joining two headlands together. This landform is known as a bar. They can trap shallow lakes behind the bar, these are known as lagoons.
Case study: what is the importance of studland
-Large employer
-Honeypot site provides income
-Biodiverse
-Habitats
Pressures on the studland ecosystem
-20 000 visitors a day
-Conjestion from traffic
-Litter
How they manage pressures on studland ecosystem
-Enforcment of illegal parking
-Zonation
-Employ more people to support the local economy for more schemes to help
Longshore drift
A process that gradually moves beach material along the coast, the action of swash and backwash results in a zigzag movement of material
Features of longshore drift
-Swash carries material up the beach
-Backwash carries material down the beach due to gravity
-Backwash always moves at a 90 degree angle
-Waves approach as an angle at the same direction as prevailing winds
When does deposition occur
When the sea loses energy and drops eroded material
How are sandy beaches formed
-Constructive waves
-Small sand particles easily carried back down the beach by backwash so beaches are long and shallow
How are shingle beaches formed
-high energy waves
-backwash is stronger than the swash so larger sediment is left behind
-weak swash dies noit move sediment for up the beach creating short and deep beacjes
Advantages of Sea walls
Prevent erosion but not movement of sediment so can’t effect other areas
Last a long time
Disadvantages of sea walls
-Strong backwash erodes wall foundations
-Expensie to build and maintain
-Ugly
Advantages of Rock armour
-Cheap to build and maintain
-Effective at absorbing line power
Disadvantages of rock armour
-Boulders sourced from other locations
-Ugly
Advantages of Groynes
-Cheap and effective
-Create larger beeches
Disadvantages of Groynes
-Affects erosion up the coast
Advantages of Gabions
-Cheap and easy to contrust
-Made from local materials
Disadvantages of Gabions
-Ugly
-Erode after 10 years
-If broken, material dangerous
Advantages of beach nourishment
-Create a wider beach which attract more tourists
-Slows waves so more protection from erosion
Disadvantages of beach nourishment
-Expensive
-Must be repeated reguarly
Advantages of dune regeneration
-Barrier between land and sea
-Help maintain natural habitats
Disadvantages of dune regeneration
-Expensive
-Requires lots of regenerattion
Hold the line
Build or maintain defences so posituon of shorline remains the same
Advance the line
New defences built at the sea side
Managed realligment
Allowing shorline to move naturally but mamaging process to direct it to certain areas
Where is Holderness
East Yorkshire, flamborough head to spurn head
Why is the erosion so fast at Holderness
-Powerfull North sea winds
-Easily eroded clay rock
-Smaller beaches so waves lose less energy
Why defend Mapleton Holderness
-Main road costs more to re route
-250 residents
How defending Holderness
2 rock groynes trapping sand to make beach bigger to absorb wave energy
Rock armour protects weak clay cliffs
Advantages of defending Holderness
-Save money on rebuilding
-Stop insurance prices rising
Disadvantages of defending Holderness
-Doubled rate of erosion down the cliff
-Less longshore drify
What defences used on the Studland
-Hold the line to protect beach huts and businesses
-Managed retreat to maintain deposition up the coast at the spit
What is Studland
Honey pot site
Importance of Studland
-Sea horse habitat
-Large employer
-Dunes have large biodiversity
Pressure on Studland ecosystem
-Conjestion from traffic
-20 000 visitors a day
-Littering
