Coasts EQ2 Flashcards
how do characteristic coastal land forms contribute to coastal landscapes? (99 cards)
1
Q
Define wavelength
A
The distance between the creeks of two waves
2
Q
Define wave crest
A
Top of the wave
3
Q
Define wave trough
A
Dip between two waves
4
Q
Define fetch
A
The distance of open water over which they move
5
Q
Define wave period
A
The time interval from crest to crest in seconds
6
Q
What are the two types of waves?
A
Constructive / destructive
7
Q
What is a constructive wave
A
When the swash is larger then the backwash
8
Q
What is a constructive wave?
A
When the backwash is stronger then the swash
9
Q
What is the wave frequency for a constructive wave?
A
6-8 per minute
10
Q
What is the wave frequency for a destructive wave?
A
13-15 per minute
11
Q
What is the motion of the water for a constructive wave?
A
Elliptical
12
Q
What is the motion of the water for a destructive wave?
A
Circular
13
Q
what is differential erosion?
A
erosion that occurs at irregular or varying rates caused by the differences in the resistance and hardness of surface materials
14
Q
name a cause of differential erosion? (one of the three)
A
permeability of the rock, sub-aerial processes, soluble material
15
Q
define sub-aerial processes
A
presence or absence of water = may affect weathering and mass movement
16
Q
name a feature you would see in the upper part of the beach..
A
any from:
- cliff face
- storm beach
- berms
- beach faces
- beach cusps
17
Q
name a feature you would see in the lower part of the beach..
A
any from:
- ripples
- runnel with water pool
- beached ridge
- runnel
- ridge
18
Q
what is a summer beach profile like?
A
beach profiles are steeper
19
Q
what are the waves like on a summer beach?
A
constructive waves which are more common then destructive waves
20
Q
what beach profile feature do you see on a summer beach profile?
A
berms at the top of the beach
21
Q
what is a winter beach profile like?
A
beach profiles are flatter
22
Q
what are the waves like on a winter beach?
A
destructive waves with strong backwash
23
Q
what beach profile feature do you see on a winter beach profile?
A
berms eroded away, backwash creates a current called a rip
24
Q
name the four erosional landforms
A
headlands and bays
wave cut notch/shoreline platform
cliff
cave, arch, stack, stump
25
how are headlands and bays formed?
1. sea attacks the section of the coast with hard and soft rock
2. it leaves a section of the land jutting out with had rock called headlands
3. it also leaves a section of the coast with soft rock and erodes it away creating a section called bays
26
give an example of an area with headlands and bays
isle of purbeck / dorset
27
how many different types of cliffs are there?
5
28
how are cliffs formed?
constant wave action and erosion against the base pf a cliff
29
how are the 5 cliff formed>
1. horizontal strata
2. rocks dip into the sea and fall
3. rocks dip inland
4. rock slides down towards the sea
5. joint act as slide planes
30
give an example of an area with cliffs
eastborne
31
how are wave cut notches and shoreline platforms formed?
1. waves breaks against the foot of the cliff close to the high tide line
2. creates a wave cut notch which begins to undercut the cliff
3. as it becomes bigger the rock above becomes unstable and collapses
4. it is repeated and the notch migrates inland and thee cliff retreats
5. leaves a shoreline platform which reduces the rate of erosion as it is usually many hundred metres long
32
give an example of an area with a wave cut notch
walton - on - the - naze
33
how are CCASS's formed?
1. joints and faults in the cliff are eroded by hydraulic action and abrasion
2. this erodes more and creates caves
3. the overlying rock collapses and creates an arch as waves break it apart
4. the gap is further enlarged by weathering and erosion and the top becomes unstable and collapses into the sea creating a stack
5. the stack is further eroded by the sea and creates a stump which can be seen at low tides
34
give an example of an area with a CCASS
Old Harry, Bournemouth, south of the UK
35
what are the 4 erosional processes?
abrasion, hydraulic action, attrition, solution
36
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
37
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
38
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
39
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
40
give 2 ways to transport sediment
tides, traction, saltation, currents, angle of wave attack, suspension, solution, longshore drift
41
define suspension
lighter sediment is carried
42
define solution
dissolved sediment
43
define saltation
smaller/ light rocks 'bounce'
44
define traction
large/heavy rocks 'roll'
45
define tides
changes in water level of seas and ocean caused by the gravitational pull of the moon
46
give 2 examples of coastal weathering processes?
- freeze thaw weathering
- wetting and drying
- salt weathering
- carbonation
- plant roots
- animals
47
what is freeze thaw weathering?
when water entres a crack or join in the rock when it rains > it freezes in the cold weather and expands in volume > repeated freezing exerts pressure on the rock which forces the crack to widen and fragments of rock to break away
48
what is the effect of freeze thaw weathering?
rock fragments are picked up by the sea and used as tools in marine erosion
49
what is wetting and drying (weathering process)?
rocks rich in clay expand when they get wet ad contract when they dry
50
what is the effect of wetting and drying?
cracks and breaks up rock
51
what is salt weathering?
salt water evaporation = leaves salt crystals behind
52
what is the effect of salt weathering?
exerts stresses in the rock causing it to break up and corrode the rock
53
what is carbonation (weathering process)?
rainwater absorbs carbon dioxide from the air to form a weal carbonic acid = causes it to be easily dissolved
54
what is the effect of carbonation?
creates easily dissolved rocks
55
what Is plant root weathering?
vegetation grows in the small cracks in the cliff face and widen as the roots grow thicker therefore breaking the rock
56
what is an effect of plant root weathering?
breaks rock apart and any decaying roots increase chemical weathering
57
what is animal weathering?
birds and animals dig burrows into cliffs
58
what is an example of chemical weathering ?
carbonation
59
what is an example of mechanical weathering?
freeze thaw weathering, wetting and drying, salt weathering
60
what is an example of biological weathering?
plant roots, animals
61
give 2 examples of coastal depositional landforms?
- spits
- beaches
- bars
- offshore bars
- tombolo's
- cuspate foreland
62
what are the stages for the formation of a spit?
1. sand shingle is moved along a coast by longshore drift
2. coastline changes direction due to a river estuary, sediment begins to build across the estuary
3. a hook is formed by prevailing wind changing direction
63
what is a spit?
long narrow feature made of sand or shingle which extends from land to sea
64
what is a recurved spit?
sand continues to move down and curve
65
what is a double spit?
two spits extending from ends of the bay
66
give an example of an area which has a spit?
Poole Harbour
67
what are the stages in forming a beach?
wave refraction crates a low- energy environment leading to deposition
68
what is a swash-aligned beach?
moves up and down the beach with little transfer
69
what is a drift-aligned beach?
transferred along the coast by longshore drift
70
what are the stages in forming a bar?
1. sediment carried across a headland by waves
| 2. traps water behind to form a lagoon
71
give an example of an area which has a bar?
cornwall
72
what are the stages in forming a offshore bar?
destructive waves erode sand from the beach with the strong backwash and deposit it offshore creating a ridge
73
what are the stages in forming a tombolo?
1. deposition occurs where waves lose their energy and the tombolo builds up
2. carry's on until it reaches the island
74
what is a tombolo?
beach that has formed between a small island and the mainland
75
give an example of an area with a tombolo?
northumberland
76
what is a cuspate foreland?
triangular -shaped headlands that extends out from the mainlands coastline
77
what are the stages in forming a cuspate foreland?
1. longshore drift from opposite directions
2. sediment deposited at the point where the two meet
3. vegetation begins to grow on deposited sediment
78
give an example of an area with a cuspate foreland?
kent
79
what is a sediment budget?
Amount of sediment available within a cell
80
What is negative feedback to a coastline?
Prevents erosion and helps to maintain a balance within the system
81
What is positive feedback to a coastline?
helps erosion by changing the balance of the coastline will a new equilibrium is reached
82
name 2 coastline sources?
- erosion of cliffs
- onshore currents
- land sediments
- wind blown sediments
- subaerial processes
83
name 2 coastline transfers?
- wave transport through swash and backwash
- longshoremen drift
- tides moving sediment
- currents
- wind alone shore
84
Name 2 coastline deposits?
- backshore
- foreshore
- nearshore
- offshore sediments
85
name 3 examples of coastal mass movement..
- solidification
- flows
- rock falls
- land slides
- slumps
- soil creep
86
name the 3 groups of coastal mass movement..
flow, slide, slump
87
what is solidification?
top layer of the soil thaws in summer but the layer below is frozen
the surface layer becomes saturated and flows over the frozen subsoil and rock
88
where does solidification occur?
in the tundra areas where the ground is frozen
89
what are flows?
increase in the amount of water causing earth and mud to flow over bedrock
90
where do flows occur?
areas with heavy rain
91
what are rock falls?
material once broken away either bounces or falls vertically to form scree at the foots of the cliff
92
where do rock falls occur?
steep rock faces/ cliffs which are exposed to mechanical weathering
93
what are land slides?
an increase in the amount of water causing sliding
| slabs of rocks slide over underlying rocks
94
where do land slides occur?
in rocks that are jointed, have bedding planes parallel to the slope or cliff
95
what are slumps?
rotational movement causing rotational scars
96
where do slumps occur?
saturated conditions, moderate to steep slopes
97
what is soil creep
the slowest form of mass movement, slow downhill movement of individual soil particles
98
name a factor affecting mass movement?
- angle of the slope or cliff
- rock type and its structure
- vegetation cover
- how wet the ground is
99
what are dispersion diagrams?
scatter graphs
