Coasts Flashcards
How are cliff retreats formed
The foot of a cliff is eroded into a wave cut notch this continues eroding until the top of the Notch collapses and these rocks get washed away this progress continues until the cliff is far back and a wave cut platform is created
What type of costal erosion is a wave cut platform
Erosional
What is a cove
A wide circular bar with a narrow entrance
How is a cove formed
They form where there a band of hard rock along the coast with a band of softer rock behind it, where there’s a weakness in the band of hard rock a narrow gap will be eroded, the softer rock behind will then be eroded much more to form a cove
What is a spit
Spits are bits of silt deposited at the sharp bend in a Coast line
How is a spit formed
Longshore drift transports sand and shingle past the bend in the Coast line and deposits it in the sea, strong wind and waves curve the end of the spit
What’s special about a spit
The sheltered area behind the spit is protected from waves so lots of material accumulate here so plants can grow
What is a bar
A bar is two spits that have joined together on each side of the headland
How is a bar formed
Both spits build up enough silt to connect and form a bar which cuts off the bay creating a lagoon
What is a tombolo
A bar that connects the shore to the island
What is a stump
A stump is a headland that has overtime eroded down and broken away from the cliff
How is a stump formed
The head land’s are eroded by hydraulic action and corrasion this forms cracks in the headland they eventually get so big rest collapses off and turns into a cave the erosion continues until the other side of the Cave is gone and it becomes an arch over time the top of the arch falls down because of gravity, this is now a stack which in turn erodes into a stump
What is a headland
a headland is an area of the resistant rock that erodes slower than the bay
How are headlands and bays formed
They both form where there are alternating bands of resistant and less resistant rock, the less resistant rock eroded Lordy creating a bay and the more resistant rock is left out creating headlands
What is a cliff retreat/wave cut platform
A result of weathering erosion and mass movements - the backward movement of a cliff
What are the four types of costal erosion “Tommy HAAS”
Hydronic action,abrasion,attrition and solution
How does hydronic action work
Waves crash against rock eroding it
How does abrasion work
Eroded rocks in the water rub against rock eroding it even further
How does attrition work
Eroded particles in the water smash into each other, they also get rounded off by the water
How does solution work
Weak acid in sea water dissolves rocks (mostly chalk and lime stone)
What are some features of constructive waves
- wave crests far apart
- gentle sloping wave front
- breaking wave spills forward
- strong swash
- gentle beach
What are some features of destructive waves
- waves close together
- steep wave front
- breaking wave plunges downward
- strong backwash
- steep beach
What’s blurff
Small barrier of silt
What’s a levee
Large barrier of silt
What are deltas
When a river reaches the sea or a lake so it gets bigger and becomes a certain shape
Types of deltas
Birds foot,cuspate and fan shaped
What are estuaries
Smaller rivers that split off into the sea
What are some hard engineering methods
Groins,sea wall,gabions,rock armour and revetments
What do groins do
Limit the impact of long shore drift
What does a sea wall do
Stops the waves reaching and eroding the land
What do gabions do
They soak the wave energy up because they are smaller rocks patched together
How does rock armour work
It soaks up the wave energy so there’s less erosion
What do revetments do
They are barriers in the water that lessen erosion
What are some types of soft engineering
Manage retreat,beach replenishment,beach re profiling and planing vegetation
What’s a concordance coastline
A coastline which has the same type of rock all the way along
What’s a discordant coastline
A coastline which has hard rock and sock rock
