Coasts EQ2 Flashcards
how do characteristic coastal land forms contribute to coastal landscapes?
Define wavelength
The distance between the creeks of two waves
Define wave crest
Top of the wave
Define wave trough
Dip between two waves
Define fetch
The distance of open water over which they move
Define wave period
The time interval from crest to crest in seconds
What are the two types of waves?
Constructive / destructive
What is a constructive wave
When the swash is larger then the backwash
What is a constructive wave?
When the backwash is stronger then the swash
What is the wave frequency for a constructive wave?
6-8 per minute
What is the wave frequency for a destructive wave?
13-15 per minute
What is the motion of the water for a constructive wave?
Elliptical
What is the motion of the water for a destructive wave?
Circular
what is differential erosion?
erosion that occurs at irregular or varying rates caused by the differences in the resistance and hardness of surface materials
name a cause of differential erosion? (one of the three)
permeability of the rock, sub-aerial processes, soluble material
define sub-aerial processes
presence or absence of water = may affect weathering and mass movement
name a feature you would see in the upper part of the beach..
any from:
- cliff face
- storm beach
- berms
- beach faces
- beach cusps
name a feature you would see in the lower part of the beach..
any from:
- ripples
- runnel with water pool
- beached ridge
- runnel
- ridge
what is a summer beach profile like?
beach profiles are steeper
what are the waves like on a summer beach?
constructive waves which are more common then destructive waves
what beach profile feature do you see on a summer beach profile?
berms at the top of the beach
what is a winter beach profile like?
beach profiles are flatter
what are the waves like on a winter beach?
destructive waves with strong backwash
what beach profile feature do you see on a winter beach profile?
berms eroded away, backwash creates a current called a rip
name the four erosional landforms
headlands and bays
wave cut notch/shoreline platform
cliff
cave, arch, stack, stump
how are headlands and bays formed?
- sea attacks the section of the coast with hard and soft rock
- it leaves a section of the land jutting out with had rock called headlands
- it also leaves a section of the coast with soft rock and erodes it away creating a section called bays
give an example of an area with headlands and bays
isle of purbeck / dorset
how many different types of cliffs are there?
5
how are cliffs formed?
constant wave action and erosion against the base pf a cliff
how are the 5 cliff formed>
- horizontal strata
- rocks dip into the sea and fall
- rocks dip inland
- rock slides down towards the sea
- joint act as slide planes
give an example of an area with cliffs
eastborne
how are wave cut notches and shoreline platforms formed?
- waves breaks against the foot of the cliff close to the high tide line
- creates a wave cut notch which begins to undercut the cliff
- as it becomes bigger the rock above becomes unstable and collapses
- it is repeated and the notch migrates inland and thee cliff retreats
- leaves a shoreline platform which reduces the rate of erosion as it is usually many hundred metres long
give an example of an area with a wave cut notch
walton - on - the - naze
how are CCASS’s formed?
- joints and faults in the cliff are eroded by hydraulic action and abrasion
- this erodes more and creates caves
- the overlying rock collapses and creates an arch as waves break it apart
- the gap is further enlarged by weathering and erosion and the top becomes unstable and collapses into the sea creating a stack
- the stack is further eroded by the sea and creates a stump which can be seen at low tides
give an example of an area with a CCASS
Old Harry, Bournemouth, south of the UK
what are the 4 erosional processes?
abrasion, hydraulic action, attrition, solution
what is abrasion?
> waves advance they pick up sand and pebbles from the seabed
transported material is hurled at the cliff hipping away at the rock
what is hydraulic action?
> air is trapped and compressed in the joints of the cliff
when the wave retreats the compressed air expands again
weakens the joint and cracks in the cliff causes pieces of rock to break off
what is solution?
> when cliffs are formed by alkaline rocks the cement bonds the rock particles together
solution by weak acids in the seawater can dissolve them
what is attrition?
> gradual wearing down of rock particles by impact of rocks smashing against each other
the pieces of rock are moves by the waves
reduces particle size and makes rocks rounder and smoother