3.1.3.3 Coastal landscape And Development Flashcards
(98 cards)
1
Q
What are the inputs in the formation of a landform?
A
Coastal geology
Climate
Nature of the waves
2
Q
What are the process of formation of a landform?
A
Erosion Weathering Deposition Wave refraction Sea level change
3
Q
What are the outputs in the formation of a landform?
A
Sediment
Landform
4
Q
On which type of coastline do headlands and bays form?
A
Discordant
5
Q
Why is wave energy focused on headlands?
A
Wave refraction
6
Q
Why are bays subject to deposition?
A
Due to the lower energy waves they recieve
7
Q
What are the main landforms o erosion?
A
Headlands and bays
Cliffs and wave cut platforms
Caves arches and stacks
8
Q
Where does a wave cut notch form?
A
Where destructive waves between the high and low tide lines at the foot of the cliff concentrate energy. So this rock faces more erosion and over time the cliff becomes undercut
9
Q
What are characteristics of a wave cut platform?
A
Smooth and flat (5 degrees)
10
Q
Why, over time, does the platform eventually cease to grow?
A
- the waves break further and further out
- wave energy is dissipated over a further distance
- rate of erosion decreases
11
Q
What is usually the maximum width of a wave cut platform?
A
500m
12
Q
Why is the formation of wave cut platforms a negative feedback loop?
A
Because over time the effects become less destructive due to the growth of the platform
13
Q
Wat are cliff profile features?
A
Caves, arches and stacks
14
Q
Where do caves, arches and stacks tend to form and why?
A
On headlands because wave refraction focuses wave energy of eroding the headlands
15
Q
What is a geo?
A
A narrow, steep sided inlet opened up by hydraulic action
16
Q
How is a cave formed?
A
Where the cracks or joints in a cliff becomes undercut by hydraulic action and abrasion
17
Q
What is a blowhole?
A
When force from the waves hit the back of a cave with full force and enlarge joints in the cave roof. If overlying rocks are sufficiently weakened, they collapse
18
Q
Why do caves often form in headlands?
A
because erosion is the strongest there
19
Q
How is an arch formed?
A
When a cave breaks through the headland and opens through
20
Q
What is a stack?
A
A tall rock formed when the roo of an arch collapses
Stands a lone from the headland
21
Q
What is a stump?
A
The remainder of when the top of a stack is weathered and eventually collapses in stages
22
Q
What are examples of cliff profile features?
A
Old Harry’s Rocks in Dorset
Twelve Apostles in Victoria, Australia
23
Q
What is a beach?
A
A temporary accumulation of sediment (store) within a sediment cell
LArgely formed of sand or shingle
Formed from material of offshore sand bars, longshore drift, wind loan sa from up coast ad ass movement
24
Q
Where do beaches form?
A
Between the highest point reached by storm waves and lowest spring tides
25
Why do sand beaches typically have a gentle slope of around 5 degrees?
Because the grains are small and easily compacted therefor little water can percolate through so th majority of th water moving up the beach wil return throughbackwash which smooths and flattens the beach
26
Why are shingle beaches usually steep at 10-20 degrees?
Because the large sediment size means they are less compacted. Therefore water can percolate better and the back wash does not pick up a lot of material from the beach back into the sea. This creates a beach which is unlikely to be eroded
27
What is a swash aligned beach?
Generally parallel to oncoming wave crests
Experience minimal longshore drift
Found on irregular coastlines where longshore drift is impeded, waves hit sections of the coast head on
28
What is a drift aligned beach?
Oriented parallel to direction of longshore drift
Have considerable amounts of sediment transported long distances a long them
Develop where a coastline is fairly regular
Can extend out from the coast line if there is a sudden change in the direction of the coastline e.g. an estuary
29
What is a spit?
An elongated, narrow ridge of land that has one end joined to the mainland and projects out into the sea or across an estuary
30
On which sort of beach does a spit usually form?
Drift aligned
31
What is a simple spit?
- straight or recurved
| - do no he minor sits, or recurved ridges, along their landward edge
32
What is an example of a simple spit?
Spurn Head - East Yorkshire
33
What is a compound spit?
- Have a series of minor spits or recurred ridges along their landward side
34
What is an example of a compound spit?
Hearst Casle Spit, Hampshire
35
What makes a spit more permanent?
When sediment is deposited above the HWM
36
What is a tombolo?
Whe a spit connects to an island from th main land
37
What is an example of a tombolo?
St Ninians in Shetland
38
What does the formation of a tombolo create?/
More sheltered conditions on the lee-side of it which may lead to deposition and salt marsh formation
39
What is a barrier beach?
When a spit extends across a bay or joins two headlands together
They can only form if there is no current lowing off the land
40
What is behind a barrier beach?
A lagoon - usually shallow and marshy
| In tropical conditions, mangrove swamps can form
41
What is an example of a barrier beach?
Slapton Ley - devon
42
What are barrier islands?
When barrier beaches become separate from the mainland
43
What happens overtime on barrier beaches?
Become vegetated, vegetation succession occurs
44
Where are barrier beaches usually formed?
Areas with low tidal ranges and gently sloping offshore coastlines
45
What is an example of barrier beaches?
The West Frisian Islands in the Netherlands
46
How are offshore bars formed?
By sediment that is deposited by coastal currents including long shore drift but they remain submerged or semi submerged beyond the breaker zone.
47
Where are offshore bars formed?
Where currents deposit sand offshore
48
Where are sand dunes more likely to form?
In areas which have large expanses of sand, a high tidal range and are exposed
Dried out at low tide
49
What are the order of dunes in sand dune formation?
```
Embryo
Foredune/Yellow
Dune Stack
Grey dune
Climax
```
50
What is the pH of the soil at an embryo dune?
8.5
51
How are sand dunes formed?
Sand is trapped by obstacles, usually on the storm berm
As more sand is trapped, the obstacles grow which leads to further deposition
Embryo dunes are colonised by pioneer species
Roots stabalise the dune
Decaying plant matter adds organic content which aids water retention
Become further stabilised by more colonisation of vegetation
52
What are some examples of pioneer species?
Marram grass
| Sea couch
53
What are charcteristics of an embryo dune?
1m high
| 80% exposed sand
54
What are characteristics of yellow dunes?
5m high, 20% exposed sand
55
What are the charcteristics of grey dunes?
8-10m high, 10% exposed sand
56
What is a dune slack and where do the form?
They form between the dunes where the water table is at the surface (ponds between the dunes where aquatic ecosystems form)
57
What is climax vegetation of a dune?
Where hardy trees/woodland grows such as birch trees, shrubs like heather and gorse grow
58
What does the increase of vegetation do to the dunes?
Increase humus levels, moisture retention, decrease pH
59
What is a humus level?
The amount of organic content
60
What is a halosere?
A salt tolerant eco-system
61
Where do mudflats and salt marshes form?
On low energy coastlines
In areas o low energy such as river estuaries where tidal currents are slowed down
Behind spits where low energy water is found
62
What is flocculation?
When particles aggregate (join together)
63
What causes flocculation?
Where sediment suspended in river estuaries meet saline water
64
What happens to the fllocculated parties at a river estuary?
Sink to the bed of the estuary because they are too heavy to still be suspended in the river flow
65
When is a mud flat exposed?
At low tide when the inter-tidal area o mud is left exposed
66
Why are mud flats not permanent features?
Because they are very susceptible to changes in sea level, wave action or changes in river discharge levels
67
Where are the largest mudflats in the UK?
Morcambe Bay - NW England
| Four river estuaries meet there
68
How do mud flats develop into salt marshes over time?
Vegetation succession / halosere
69
What is a storm berm?
Above spring tide level
| Flat, at the top of the beach
70
What are berms?
A series of ridges that mark high tide lines
| Built by constructive waves
71
What are cusps?
Curved sided channels that channel incoming swash into the centre of a cusp which creates a stronger backwash flowing out.
Form where sand meets shingle
72
What are ripples?
Marks of the waves at high tide
73
What are ridges?
Where backwash deposits sediment parallel to the coastline
| At the foreshore/inter tidal zone
74
What are runnels?
Where water runs back to the sea it forms marks in the beach that are perpendicular to the coastline
75
What is isostatic sea level rise?
Change in the level of the land relative to the sea
| Local or regional change
76
What are examples of isostatic sea level change?
Fold mountain formation
| Post glacial readjustment (isostatic rebound)
77
Where is post glacial readjustment happening?
Scotland
78
What is eustatic sea level change?
The rise/fall in sea level as a result of a change in the actual level of water in the oceans
Global changes
79
How many years ago were sea levels 110m below what they are now?
18,000 years ago
80
How much are sea levels now rising each year? And why?
3mm a year - thermal expansion
81
What landforms are formed as a result of falling sea levels a long coastlines of emergence?
Caves
| Raised beaches - relict features
82
Where is an example of relict cliffs?
King's Cave on Arran
83
What are features of coastlines of submergence?
Rias
Fjords
Dalmatian coasts
84
What is a ria and what is an example of one?
Flooded river mouth/valleys
| - The mouth of the river Exe at Exmouth
85
What is a fjord and what is an example of one?
Flooded glacial valleys (valleys that have been eroded by glaciers)
- Sognefjord in Norway - 200km long
86
What are characteristics of a fjord?
U shaped valleys
Steep sides, nearly vertical
Shallow at the mouth
87
Why are the fjord valleys flooded?
Because of sea level rise
88
What are Dalmatian coasts?
When the topography of the land runs parallel to the coastline and ecomes flooded by sea level rise
small islands and peninsulas are aligned parallel to, but offshore from, the mainland
89
Outline two impacts of sea level change at locations in the UK
north norfolk/ The Fens, agriculture at risk if flooded
| London - at risk of inundation which puts the population and important land se at risk
90
Outline two impacts of sea level rise outside the UK
Maldives - being reclaimed by the sea
| Bangladesh - 11% is likely to be flooded
91
What are the causes of isostatic change?
Tectionic activity
Glaciation
Post glacial readjustment
92
What are the causes of eustatic change?
thermal expansion
| Tectonic activity
93
How does tectonic activity cause isostatic change?
Land moving up or down , earthquake of foldmountain formation
+ Tohoku earthquake 2011, some sections of the coastline dropped 0.84m
94
How does glaciation cause isostatic change?
When glaciers and ice sheets surpressed land into the upper layer of the mantle (ice age- 18,000 years ago)
95
How does isostatic rebound cause isostatic change?
When the asthenosphere rebounds after glaciation
96
Why does thermal expansion of water cause eustatic change?
As water is heated by global warming, it expands so leads to a larger volume of water which takes up more space and causes sea level to rise
97
How does changes in the extent of ice sheets cause eustatic change?
When ice sheets form, water is removed from the sea causing levels to drop
When ice melts, more water is available to ocea stores so sea levels rise
98
How does tectonic activity cause eustatic change?
When new land is formed under the ocean, it takes up space in ocean basins and displaces the water
