Coasts Flashcards
(208 cards)
1
Q
What is a dynamic equilibrium?
A
a condition of balance in the natural world
2
Q
What are some features of high energy coastlines?
A
cliffs, gentle or vertical
rocky coastline- clear boundary between coast and backshore
3
Q
What are some features of sandy low energy coasts?
A
beach covered at high tide
marram grass not often covered by water- it stabilises coast and reduces erosion
4
Q
What are some features of low energy estuarine coasts?
A
salt marsh not covered at high tide
mud flats covered at high tide
difficult to know where the boundary between coast and land is
5
Q
What is the lithology of the coast?
A
the resistance and porosity/permeability of the rock
6
Q
How long is the Dutch coastline?
A
About 100km long and mainly made up of dune areas
7
Q
How far has the Dutch coastline eroded in four centuries?
A
5km in some places
8
Q
What is the backshore?
A
The back part of the beach just in front of the cliff
9
Q
What is the foreshore?
A
The area of the beach between the high and the low water mark
10
Q
What is the nearshore?
A
The area between the low water mark and the deep water
11
Q
What is the offshore?
A
The sea
12
Q
Which area of the littoral zone experiences the most natural processes?
A
foreshore
13
Q
Which area of the littoral zone experiences the most human activity?
A
nearshore
14
Q
Are high or low energy coasts rocky?
A
high energy
15
Q
Are storm conditions found on high or low energy coasts?
A
high
16
Q
Is erosion and transport found in high or low energy coastal environments?
A
high
17
Q
Are destructive waves found in high or low energy coasts?
A
high
18
Q
Are waves with long fetch found on high or low energy coasts?
A
high
19
Q
Are sediments from offshore currents found in high or low energy coasts?
A
high
20
Q
Are cliffs, wave cut platforms, and stacks found on high or low energy coasts?
A
high
21
Q
Are sediments from mass movements found in high or low energy coastal environments?
A
high
22
Q
Are destructive waves found in high or low energy coasts?
A
high
23
Q
Are coastal plains found in high or low energy coasts?
A
low
24
Q
Are waves with a short fetch found in high or low energy coasts?
A
low
25
Are sediments from rivers found in high or low energy coasts?
low
26
Are less powerful waves found in high or low energy coasts?
low
27
Are beaches, sand dunes, spits and bars found in low or high energy coasts?
low
28
Are lowland areas in high or low energy coastal environments?
low
29
Is deposition and transport found in high or low energy coasts?
low
30
Are high or low energy coasts more sheltered?
low
31
What is the littoral zone?
The backshore, foreshore, nearshore, and offshore
32
What is the cliff profile dependent on?
The resistance of the rock
33
What happens to headlands when they become more exposed?
Wave refraction takes place causing their energy to be concentrated on both sides of the headland forming caves, arches, and stacks
34
What is an example of a natural harbor?
Lulworth cove
35
When are coves formed?
Hard Rock in concordat coastlines acts as a barrier to the softer rock behind it preventing erosion. But if the hard Rock is breached, the softer rock is exposed and a cove can form
36
What was stage one in the formation of Lulworth cove?
Formation began after the last ice age
| A river swollen by melt water flowed overland to the sea
37
What was stage 2 in the formation of Lulworth cove?
The river cut a valley and breached the Portland Stone. The rising sea flooded into the valley and started to exploit joints and weaknesses in the Purbeck Beds
38
What was step 3 in the formation of Lulworth cove?
The soft wealden clay eroded and the cove formed a pan shaped inlet
39
What was step 4 in the formation of Lulworth cove?
The cove continued to enlarge, eroding through the greensand rock
40
What was step 5 in the formation of Lulworth cove?
Erosion was contained and slowed down by the semi hard chalk beds to produce the semi landlocked cove of today
41
When do dalmatian coasts form?
They form where the geology creates valleys parallel to the coast so that when sea level rises, a series of elongated islands remain offshore
42
What is an example of a dalmatian coast?
Croatia
43
How do haff coasts form?
Meltwater rivers in the land beyond the ice from in the Devensian glacial period deposited thick layers of a sand and gravels onto outwash plans. When the glaciers melted, constructive waves pushed sands and gravel landward as sea levels rose. Sand ridges formed bars across bays and river mouths with trapped river water forming a lagoon behind.
44
What lithology forms steep cliffs?
Uniform horizontal strata
45
What is the cliff profile if the rocks dip gently seawards with near vertical joints?
Joints opened by weathering and pressure release
46
What is the cliff profile if there is a steep seaward dip?
Rock slabs slide down the cliff along bedding planes
47
What produces a stable steep cliff profile?
Rocks dipping inland
48
What produces slope over wall cliffs?
Marine cliffs of hard Rock beds
| With a periglacial slope on top
49
How are blowholes produced?
Erosive waves may blast their way vertically through vertical lines of weakness in the roofs of caves forming a blow hole on the cliff top
50
What is an example of a blow hole?
Spouting horn on kaua'i, one of hawaii's chain islands is the result of differential erosion of a lava tub
51
What happens to a blow hole in stormy conditions?
Sea spray may sprout from blowholes
| or when the tide is high enough
52
Where are notches formed?
Underneath the cliff face around the mean high water mark
53
In what rock are notches particularly common?
Limestone
54
where are caves formed?
around the mean high water mark, extending under the cliff base
55
What are notches usually a result of?
wave erosion, bioerosion, and weathering
56
What are caves formed as a result of?
structural weaknesses in rock, for example, joints and bedding planes exploited by wave action
57
What is a salt marsh?
the vegetation that occurs on muddy shores between the mean high water mark and extreme high spring tides
58
Where can mudflats be found?
sides of estuaries or coasts protected by narrow entrances or depositional features
59
What is a mudflat/how are they formed?
they are on a sea shore with very little wave action so muds, silts and clays can fall out of suspension and be deposited
60
How does a lower salt marsh more developed than a mudflat?
It spends less time underwater and the height of the mud increases
61
How is an upper salt marsh more developed than a lower salt marsh
abiotic factors become more favourable to plants
| height is increased so it is immersed in water much less frequently
62
How is an upland bank more developed than an upper salt marsh?
It is only immersed once or twice a year
| If there is fresh water at the back it will develop into a scrub area and then a forest
63
What is an upland bank called if it is affected by human activity?
plagio-climax community
64
What are the characteristics of plants in mudflats?
the roots of pioneer plants help consolidate the mud by binding it together and trapping more in its upper parts
seeds are blown or washed in
65
What are the characteristics of plants in lower salt marshes?
plants grow bigger than in mudflats, and there are more of them
the vegetation becomes "closed", forming a continuous carpet on the ground
66
What are the characteristics of plants in upper salt marshes?
pioneer plants tend to be out-competed and replaced by equilibrium species which are more slow growing and get older
67
What are examples of plants in mudflats?
pioneer species like glasswort or cord grass
68
What are examples of plants in lower salt marshes?
salt marsh grass and sea aster
69
What are examples of plants in upper salt marshes?
sea purslane and thrift/sea pink
| scurvy grass and sea lavender
70
What are examples of plants in upland banks?
rush and sedge
| red fescue grass at drier parts
71
What is the halosere?
a series of communities displaying a successional sequence where the plants are adapted to salt water
72
What type of sand makes up embryo and fore dunes?
alkaline sand
73
What are characteristics of embryo and fore dunes?
on-shore winds
seaweed (humus build up)
transient
sand building up
74
What are the plant characteristics of fore and embryo dunes?
scattered individuals
waxy leaves
low growing
75
What is an example of a plant found in embryo and fore dunes?
sandwort
76
What is an example of a plant found in yellow dunes?
marram grass
77
How high can yellow dunes become?
top dunes above high tide level
78
What are characteristics of yellow dunes?
surface continually blown away and replenished with fresh sand
reduced wind speed
79
What type of roots do plants have in yellow dunes?
long tap roots
80
What type of of leaves do plants have in yellow dunes?
inrolled leaves
81
What are characteristics of plants in yellow dunes?
salt intolerant
thrives on being buried by sand
underground rhizomes to stabilise sand
82
What are characteristics of grey dunes?
increased humus content
surface lichens
sand no longer accumulating
marram grass not able to compete well
83
What are characteristics of plants found in grey dunes?
many plants co-existing
mainly perennials
stabilising plants liking increased organic matter content
84
What are examples of plants found in grey dunes?
grey lichen and heather
85
What are characteristics of dune slack?
damp, low lying hollows
86
What is the soil like in dune slacks?
soil is acidic and PH variable
87
When do dune slacks have a high water table?
winter
88
What types of plants are found in dune slacks?
moisture loving plants
89
What is an example of a plant found in dune slacks?
rushes
90
What are characteristics of heath/woodland?
high organic matter content
nutrient rich
shelter developed
91
What is the soil like in heath/woodland?
acidic
92
What are the characteristics of plants found in heath/woodland?
acid loving plants co-existing
| woody perennials plus understory plants
93
Plant examples found in heath/woodland?
heather/woodland
94
how are anticlines and synclines formed?
by plate collisions folding rocks
95
What are faults?
major weaknesses within rock layers either side of a fault line
96
what are joints?
they occur in most rocks in regular patterns dividing rock strata up into blocks
97
What are bedding planes?
different layers of deposition in sedimentary rocks
98
what are fissures?
small cracks in a rock that can be a few cm or mm
99
What are anticlines?
folds in rock that are convex up or A shaped
100
what are synclines?
folds in rock that are concave down or U shaped
101
What landforms are associated with concordant coasts?
coves
| haff and dalmation coasts
102
Where are complex depositional features such as spits more likely to be found?
concordant coasts where LSD can operate
103
What does the horizontal bedding of resistant rock lead to in discordant coasts?
vertical cliffs and micro features such as notches and caves
104
What type of cliff profile does well jointed granite or limestone create?
blocky profiles and micro features like blowholes
105
How does vegetation stabilise the coast (3 reasons)?
the roots bind sediment together making it harder to erode
submerged plants provide a protective layer from the water
protect sediment from wind erosion
106
how do submerged plants protect the coast?
they provide a protective layer from the moving water
107
how do plants protect the coast from wind erosion?
by reducing the wind speed at the surface due to friction with the plant
108
how do the roots of plants protect the coast?
they bind sediment together making it hard to erode
109
What are xerophytic plants?
plants that can tolerate very dry conditions
110
What are halophytic plants?
plants that can tolerate salt conditions
111
What are the rooting conditions like in the pioneer stage of sand dune development?
poor due to drought, strong winds, salty sea-water immersion and alkaline conditions created by sea shells
112
What are the three stages of sand dune development?
the pioneer stage,
the building stage,
the climax stage
113
What happens in the pioneer stage of sand dune development?
seeds are blown in by wind or washed in by the sea
| the wind moves the sand in the dunes and this allows rainwater to soak through rapidly
114
What are the five different types of sand dune?
```
embryo and fore dunes
yellow dunes
grey dunes
dune slack
heath/woodland
```
115
What do pioneer plants do in the pioneer stage of dune development?
they colonise the area first and change the conditions of the soil
116
How do pioneer plants change the condition of the soil (3 ways)?
by adding humus when they decay
by retaining moisture (the soil becomes less alkaline)
by trapping and holding together the sand or mud with their roots
117
What happens in the building stage of dune development?
new plants establish and take over
| less hardy plants can now grow and start to shade out the pioneers
118
what happens in the climax stage of sand dune development?
there is a balance between all the natural factors and the final vegetation establishes itself- often a taller and more complex species
119
What colour change occurs in the building stage of sand dune development
as plants colonise the dunes, the sand disappears and the dunes change colour from yellow to grey
120
what is the role of humus in building stage of sand dune development?
it creates more fertile growing conditions
| the soil becomes more alkaline as plants grow and trap water
121
When do dune slacks occur?
in the climax stage of dune development when the water table reaches or nearly reaches the surface
122
Where do sand dunes occur?
where there is a lot of sand (low energy coast)
large areas where the sand can dry out
onshore winds to blow sand on land
an obstacle to trap the sand
123
What is a wave's potential energy proportional to?
its height
124
what does the wave length depend on?
wind strength
125
what are waves a result of?
friction between the wind and the sea surface
126
what releases wave energy?
forward movement
127
What must the conditions be for a wave to break?
the depth of the sea must be less than the wavelength
128
What happens to the wave orbit as it reaches the shore?
it becomes elliptical because of friction on the seabed
129
What is the dominant wind?
it produces the largest and most damaging waves at any given point on the coast
130
what is the prevailing wind?
the most frequent wind
131
what are the dominant and prevailing winds on the west coast of the UK?
both from the west
132
what type of wave has a long wave length of up to 100m?
constructive
133
which wave type leads to a steeper beach gradient?
destructive
134
Which wave type has a shorter wave length of up to 20m?
destructive waves
135
What is the motion of the water like in destructive waves?
circular, because of a deeper nearshore zone, directing the mass of wave downwards on the beach when it breaks.
136
Which type of wave has a stronger backwash and what does this do?
destructive- it erodes beach material and carries it offshore creating an offshore ridge or bar
137
Which type of wave leads to the formation of storm ridges or berms?
Destructive waves when they throw material to the back of the beach during storms
138
Which wave type has a lower frequency and what does this mean?
constructive- it means that each wave can complete its cycle and so the swash is not interrupted.
139
Which wave type has a frequency of under 10 waves per minute?
destructive
140
What is the motion of water like in constructive waves?
it is elliptical, giving a strong forward movement
141
What wave type leads to a shallower beach gradient?
constructive- beach gradient is flatter with a steep berm at the top of beach
142
Which wave type leads to wider beach?
constructive- sediment is moved up the beach making it wider
143
Which wave has a shorter wave height?
constructive waves are less than 1m higher
144
Which wave has a stronger swash than backwash?
constructive
145
Which wave type has a higher wave height?
destructive- over 1m high
146
Which type of wave removes sediment from beaches and cliffs?
destructive
147
What are cusps?
sort of semicircle formations in the sand where the flat side is open
material is deposited outside the semicircle next to the opening causing waves to split and erode the back of the semicircle/cusp, thus causing more material to be deposited at the front
148
What are Ridges and Runnels?
the spreading out of the waves' energy across a wide are of beach tends to produce ridges and intervening depressions called runnels.
Cross-section of beach would show:
/\/\/\/\/\/\/\______/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\_______/\/\/\/\
149
What are berms/ridges?
material thrown to the back of a beach during storms
150
On which type of beaches are berms/ridges more common?
more common on pebble beaches
151
What is attrition?
beach material knocked together in the water reducing size and increasing roundness and smoothness
152
What rock type does attrition most affect?
impacts soft rock the most
153
What is abrasion?
Sediment picked up by breaking waves is thrown against cliff faces- acting like sandpaper
154
What rock type does abrasion most affect?
impacts soft rock the most
155
What is hydraulic action?
the wave power eroding the sediment. When a wave hits a cliff, air is forced into cracks under high pressure, widening the cracks.
156
What is solution/corosion?
seawater and salt spray from waves may react with rock minerals to dissolve them.
157
What rock type does hydraulic action most affect?
sedimentary and igneous
158
What rock type does solution most affect?
soluble rock is more susceptible
| chalk and limestone
159
When and why does water motion in a wave become elliptical?
the water motion becomes elliptical near beach due to shore friction (water becoming more shallow) slowing wave base
160
What are the sub ariel processes?
mass movement and weathering
161
What are the marine processes?
erosion, transport, and deposition
162
What are the different types of erosion?
attrition, abrasion, hydraulic action, and solution
163
What are the different types of transport?
traction, solution, suspension, and saltation
| but these are in drift-aligned coasts with LSD
164
What are the different types of deposition?
floculation and gravity setting
165
What are the different types of mass movement?
rockfall, slumping, topple, slides
166
What are the different types of weathering?
mechanical, biological and chemical
167
What are the different types of mechanical weathering?
freeze thaw and salt crystallisation
168
What are the different types of biological weathering?
seaweed acids and boring
169
What are the different types of chemical weathering?
carbonation and oxidation
170
Where on cliffs are cracks formed?
in the intertidal zone
171
How are cracks in cliffs formed for?
cracks are opened up by hydraulic action which pressurises air, causing the crack to widen (further widened by weathering)
172
How are caves formed?
cracks in cliffs are formed into caves by hydraulic action and abrasion
173
How are caves made larger?
wave refraction distorts the wave direction, causing destructive waves to concentrate on the headland
174
How are natural arches formed?
a cave will break through the headland- or 2 caves that were back to back. Vertical joints are exposed by tall breakers associated with destructive waves. Joints can also be weathered from above.
175
What may form in/around natural arches?
blow holes
176
How are stacks formed?
Wave cut notches erode and widen the base of an arch until it collapses
177
How are stumps formed?
A stack is eroded by hydraulic action and abrasion through wave cut notches. Sub ariel processes also weaken it from above until it becomes a stump.
178
What four things influence the size of a wave?
1- water depth
2- fetch (distance the wave has traveled)
3- wind speed
4- time the wind blows for
179
Which five factors lead to short term variations in beach morphology?
storms, tide, change in wind direction, change in currents, sub ariel processes
180
Which four factors lead to long term variations in beach morphology?
human activity- dredging and coastal management
dams
climate change causing more storms
sea level rise
181
What is an example of a wave cut platform?
Flamborough
182
How are wave cut platforms formed?
the sea creates a wave cut notch through hydraulic action/abrasion/solution. Backwash transports material from the base of the cliff, and the weight of the unsupported cliff causes it to collapse (weathering weakens the top of the cliff).
183
Where is the high tide level in the formation of a wave cut platform?
at the top of the wave cut platform
184
Where is the low tide level in the formation of a wave cut platform?
the bottom of the wave cut notch/platform
185
Where are steep cliffs formed?
where the land consists of hard, more resistant rock
186
What is an example of steep cliffs being formed from hard rocks?
Igneous rocks such as granite and basalt form cliffs along the Cornish Atlantic coast at Lands End
187
Where are sloping cliffs formed?
in areas of softer rock such as clay, shale, and some sandstones as they erode more easily.
188
Which different directions can sedimentary rock strata be laid down and what affect does the direction have?
sedimentary rocks that have been laid down in distinct strata may dip towards the sea or away from it. This presents either a smooth surface towards the seas or a rough broken surface. A smooth surface will better resist waves than a broken one.
189
How can equilibrium be maintained?
by negative feedback
190
How are beaches formed?
the strong swash of a constructive wave deposits the largest material at the top of the beach. As the upper beach builds up, the backwash becomes even weaker because a greater proportion of the water by percolation, rather than running down the beach. The weak swash of a destructive wave deposits material at the base of the beach. It cannot advance further up the beach as it is destroyed by the backwash from the previous breaking wave.
191
What is percolation?
the movement of water through the soil/underlying porous rock to be collected as groundwater
192
Where are spits formed?
they are formed on drift aligned coasts where the coast suddenly changes direction (eg. across a river mouth)
193
How are spits formed?
LSD continues to deposit material across a river mouth which causes a long bank of sand and shingle to form.
194
What forms on the inside of spits?
salt marshes
195
What can cause a spit to have a recurved end?
changes in prevailing wind and wave direction. Over time several recurved ends may form as waves return to their dominant direction.
196
How do dunes form on spits?
where the wind is strong enough to lift sediment off the beach, dunes may form
197
What affect does dune formation have on spits?
dunes add stabilization to spits when pioneer plants such as marram grass anchor the sand.
198
How are spits stopped from growing completely across a river mouth?
the river outlet removes any material deposited
199
What is a bar?
A spit that joins together two headlands
200
When are bars particularly pronounced?
At low tide when they become exposed and in the stormy season.
201
What do/cause bars do at high tide?
they make the water shallow which often causes waves to break early
202
What may form within a bay as a result of a bar?
a lagoon- if a bay is cut off from the sea by a bar that connects the two headlands on either side of the bay
203
Where is a tombolo formed?
Where a spit links the mainland to an island
204
What is a double tombolo and what can it do?
it is when 2 tombolos leave the mainland to connect to the same island. A double tombolo can enclose a lagoon.
205
What type of deposition creates a tombolo?
low energy deposition due to wave refraction around the island
206
What happens if a lagoon is enclosed by a bar or a double tombolo?
the lagoon may be gradually infilled as a salt marsh and over time will be infilled by deposition. During a period of lower mean sea level they become emergent and are built up by swash and wind-carried sand.
207
Where are barrier bars common?
along low coasts
208
How are offshore bars formed?
the waves excavate a trough in the shallows. The sand kicked up is either deposited on the beach or in an offshore trough. Sand suspended in the backwash and in rip currents add to the bar, as does some sand moving shoreward from deeper water.
