content eq1 Flashcards
1
Q
What are the four main subdivisions of the littoral zone?
A
Offshore, Nearshore, Foreshore, Backshore (ONFB - Okay Now Fry Bananas!)
2
Q
Fill in the blank: The _______ zone is the area of shoreline where land is subject to wave action.
A
Littoral
3
Q
Which part of the littoral zone is the deepest and beyond the point where waves begin to break?
A
Offshore
4
Q
What is the breaker zone and where is it found?
A
The area where waves break due to seabed friction, found in the Nearshore
5
Q
Which part of the littoral zone lies between the high tide and low tide mark?
A
Foreshore
6
Q
The backshore is only affected by wave action during what kind of events?
A
Major storm events
7
Q
Name the three types of coastal landscapes in the littoral zone.
A
Rocky, Sandy, Estuarine
8
Q
Match the coastal type to its description: Rocky Coastline →
A
High relief, resistant geology, high energy, destructive waves
9
Q
Sandy Coastline →
A
Low relief, less resistant geology, low energy, constructive waves
10
Q
Estuarine Coastline →
A
Low relief, salt marshes/mudflats, deposition > erosion, low energy
11
Q
What type of coastal landscape is found in areas of high relief with resistant geology?
A
Rocky, cliffed coastline
12
Q
Why do sandy coastlines form in low-energy environments?
A
Deposition > erosion, constructive waves, less resistant geology
13
Q
Fill in the blank: Estuarine coastlines are commonly found at ______ and are dominated by ______.
A
River mouths, deposition
14
Q
What makes the littoral zone a dynamic environment?
A
Constantly changing inputs, through-flows, and outputs of energy and material.
15
Q
Name two short-term changes that affect the littoral zone.
A
Tides (lunar month cycles), wave energy changes due to weather.
16
Q
What is a long-term change that influences the littoral zone?
A
Sea level rise due to climate change.
17
Q
Fill in the blank: The ______ zone is the area where friction between the waves and the seabed may distort wave shape.
A
Offshore
18
Q
What physical process causes waves to break in the nearshore zone?
A
Friction with the seabed distorts wave shape, causing it to break.
19
Q
What landforms might be found at the breakpoint between offshore and nearshore?
A
Breakpoint bars (sandbanks formed by breaking waves).
20
Q
Fill in the blank: The _______ zone is between the high tide and low tide marks and is where most beach processes occur.
A
Foreshore
21
Q
Why is the backshore only affected by waves during storms?
A
Because waves don’t normally reach this area unless storm surges or high-energy conditions push water further inland.
22
Q
What wave type is most dominant on a rocky coastline?
A
Destructive waves (high energy, strong backwash, erosion > deposition).
23
Q
Fill in the blank: Sandy coastlines form in ______-energy environments where ______ is greater than ______.
A
Low, deposition, erosion.
24
Q
Name two features found in estuarine coastlines.
A
Salt marshes and mudflats.
25
Why do estuarine coastlines tend to form at river mouths?
Because river sediment is deposited due to reduced wave energy.
26
True or False: Sandy coastlines are usually found in areas with high-energy waves and resistant geology.
False! They form in low-energy environments with less resistant rock.
27
What are the three main factors that cause change in the littoral zone?
Energy inputs (waves, tides, currents), sediment supply, sea level change.
28
Fill in the blank: Short-term changes in the littoral zone include ______ variation and ______ cycles.
Wave energy, tide.
29
Name two causes of long-term changes in the littoral zone.
Climate change (rising sea levels), isostatic or eustatic sea level change.
30
Why do tides change over a lunar month?
Tides are controlled by the gravitational pull of the moon, which changes in intensity over a month.
31
How do storms impact the littoral zone?
Increase erosion rates, overwash deposits, reshape beaches and dunes.
32
What two geological factors are used to classify coasts?
Lithology (rock type) and structure (rock arrangement).
33
Fill in the blank: Geology can classify coasts as ______, ______, or ______.
Rocky, sandy, or estuarine.
34
What are the two structural classifications of coastlines based on rock arrangement?
Concordant and discordant.
35
Match the term to its definition:
Concordant coast → Rock strata runs parallel to the coast.
36
Discordant coast →
Rock strata is aligned at perpendicular angle to the coast.
37
How does tectonic activity influence sea level change?
Land can be uplifted (causing local sea level fall) or subside (causing local sea level rise).
38
Fill in the blank: Climate change causes sea levels to rise and fall in a ______-year cycle due to changes in Earth's orbit.
100000
39
How long do glacials last and what happens to sea levels?
90,000 years – sea levels fall as ice sheets expand.
40
How long do interglacials last and what happens to sea levels?
10,000 years – sea levels rise as ice sheets melt.
41
What happens to sea levels when the Earth exits an ice age?
Sea levels rise even more as all surface ice melts.
42
Name three energy inputs affecting coasts.
Waves, tides, and currents.
43
Fill in the blank: The main energy input for coasts is ______.
Waves.
44
How often do tides ebb and flow?
Every 12.5 hours.
45
Name three additional energy inputs affecting coastal processes.
Gravity, atmospheric processes (wind/weather), and tectonics.
46
How are coasts classified based on energy inputs?
High-energy coasts (erosion-dominated) and low-energy coasts (deposition-dominated).
47
Fill in the blank: Coasts receive sediment inputs from ______, ______, ______, ______, and ______.
Waves, wind, tides, currents, and mass movement.
48
How does tectonic activity influence sediment inputs?
Can trigger mass movement, landslides, and uplift/subsidence, altering sediment supply.
49
What happens when erosion > deposition?
Net sediment loss → coastline retreats (eroding coastline).
50
What happens when deposition > erosion?
Net sediment gain → coastline advances (outbuilding coastline).
51
What are the two long-term processes that classify coasts as advancing or retreating?
Emergent and submergent coastlines.
52
What are the two short-term processes that classify coasts as advancing or retreating?
Eroding and outbuilding coastlines.
53
Fill in the blank: A coastline that is gaining sediment and moving seaward is called an ______ coastline.
Advancing (outbuilding).
54
Fill in the blank: A coastline that is losing sediment and retreating inland is called a ______ coastline.
Retreating (eroding).
55
What is the main difference between rocky coasts and coastal plains?
Rocky coasts = resistant geology, high-energy, erosion > deposition.
56
Coastal plains =
sediment-rich, low-energy, deposition > erosion.
57
Fill in the blank: Rocky coasts result from ______ geology and form in ______-energy environments.
Resistant, high.
58
Fill in the blank: Coastal plains result from the supply of ______ and form in ______-energy environments.
Sediment, low.
59
What process dominates rocky coasts?
Erosion (due to waves, wind, and rain).
60
What process dominates coastal plains?
Deposition (coastal accretion builds up sediment).
61
How much of the UK’s coastline is rocky coast?
About 1,000 km.
62
Where in the UK are rocky coasts most common?
North and west UK.
63
Match the rocky coast to its relief:
High-relief → 427m Conachair Cliff (Isle of Hirta, Outer Hebrides).
64
Low-relief →
3m cliffs at Chapel Porth, Cornwall.
65
Why do rocky coasts erode slowly?
They have resistant lithology (rock type) and strong geological structure.
66
Fill in the blank: Rocky coasts form where ______ > ______, making them erosion-dominated.
Erosion, deposition.
67
What happens to sediment in a high-energy rocky coast environment?
It is continuously moved, transported, and redeposited by waves.
68
What are the key characteristics of coastal plain landscapes?
Flat, low-relief, sediment-rich, poor drainage, wetlands/marshes.
69
Fill in the blank: Coastal plains experience a net accumulation of sediment because ______ > ______.
Deposition, erosion.
70
What landforms are found in the littoral zone of a coastal plain?
Sand dunes, beaches, mudflats, salt marshes.
71
What is the main process that causes coastal plains to form?
Coastal accretion (continuous net deposition of sediment).
72
What are two main sources of sediment for coastal plains?
1. Offshore (waves, tides, currents).
2. Terrestrial (rivers, glaciers, wind, mass movement).
73
Match the coastal plain to its composition:
Sandy coasts → Sands, shingles, cobbles.
Estuarine (alluvial) coasts → Clays, silts, mud.
74
Where in the UK are coastal plains most common?
South and east UK.
75
What are the two main ways coastal plains form?
1. Coastal accretion (net sediment deposition extends coastline).
2. Sea level change (falling sea level exposes continental shelf).
76
How do plants contribute to coastal plain formation?
Plants colonize shallow water, trap sediment, and form organic deposits when they die.
77
Give an example of a coastline formed by sea level fall.
The Atlantic coastline of the USA.
78
What is dynamic equilibrium in coastal plains?
Erosion = deposition → sediment stores remain unchanged despite constant energy flow.
79
What is weathering?
The breakdown of rock in situ by mechanical, biological, or chemical processes.
80
What is erosion?
The breakdown and transport of rock by an external force (e.g. waves, rivers, wind).
81
Fill in the blank: Marine processes such as ______ erosion and terrestrial processes such as ______ movement shape coasts.
Wave, mass.
82
What is mass movement?
The downslope movement of material due to gravity.
83
What is the main factor responsible for the formation of concordant and discordant coasts?
Geological structure (rock arrangement and characteristics).
84
Fill in the blank: Geological structure refers to the characteristics and ______ of rock units.
Arrangement.
85
What are strata?
Different layers (beds) of rock.
86
What is a bedding plane?
The interface between two sedimentary strata where bonding is weaker.
87
What is deformation?
The degree of tilting or folding of rock layers.
88
What is dip?
The angle of inclination of tilted strata.
89
What is the difference between a fault and a joint?
Fault = rock fractures with movement. / Joint = rock fractures without movement (e.g., cooling shrinkage in igneous rock).
90
Fill in the blank: Concordant coasts form where rock strata runs ______ to the coast.
Parallel.
91
What kind of landforms can be found along some concordant coasts?
Long, narrow islands/mountains running parallel to the coastline.
92
What are the two alternative names for concordant coasts?
Dalmatian coasts (Croatia) (islands) and Pacific coasts (Chile) (mountains).
93
Why are some concordant coasts called Dalmatian coasts?
Because the Dalmatian region of Croatia has many long, narrow islands parallel to the coast.
94
Fill in the blank: Discordant coasts form where rock strata is aligned at a perpendicular ______ to the coastline.
Angle.
95
What distinctive landforms are common on discordant coastlines?
projecting headlands and sheltered bays (crenellated pattern)
96
Why do discordant coasts have headlands and bays?
Because softer rock erodes faster, forming bays, while harder rock remains as headlands.
97
What is another name for discordant coasts?
Atlantic coasts (named after Cork coastline in Ireland).
98
Give an example of a well-known discordant coastline.
Cork coastline - Ireland
99
What is morphology in coastal geography?
The shape of landscape features, influenced by geological structure.
100
Examples of Discordant coastlines
Swanage bay - Isle of Purbeck east Dorset
Bantry Bay - Cork coastline
101
What two main types of concordant coastlines exist?
Dalmatian coast
Haff coastlines
102
Concordant - Dalmatian
formation: * African and Eurasian plates moving towards each other compressed Carboniferous Limestone during the Alpine Orogeny 50 million years ago.
- This causes deformation of the Eurasian plate as it gets crumpled creating anticlines and synclines
- Pleistocene -> Holocene = sea levels rose causing the coastal inlets to be flooded leaving the anticline exposed, i.e. sea level rise at the end of the Devensian Glacial overtopped the low points of the anticlines and the sea flooded synclines.
-> This produces lines of narrow islands parallel to the coast formed by projecting sections of anticlines.
* Lines of islands separated by narrow sea channels parallel to the coast (sounds)
103
Characteristics of Dalmatian
* Croatia - Adriatic Sea
* Micro tidal range
* Primary coast (tectonic faults)
* Submergent
* Low wave energy
104
Concordant - Haff coast
These form where deposition produces unconsolidated geological structures parallel to the coastline.
During the Devensian glacial the sea level was about 100 m lower than today as water was retained in huge ice sheets.
Meltwater rivers on land beyond the ice front deposited thick layers of sand and gravels onto outwash plains (sandurs)
In the Holocene Interglacial constructive waves pushed the ride of sands and gravel landwards as sea levels rose.
Sand ridge formed bars across some bays and river mouths, with trapped river water forming a lagoon behind (callled haffs in Poland on the Baltic Sea)
For example the Neman Haff behind the bar running from the Kaliningrad in Russia to the Lithuanian coast at the mouth of the river Neman.
Chesil Beach in Dorset was formed this way. Shingle ridge reconnected island of Portland Bill to land (a tombolo)
105
characteristics of haff
* Poland, Baltic Sea between poland and lithauania
* Primary Coast
* Submergent
* Microtidal
* Low wave energy
106
Concordant - Lulworth cove
* Secondary, microtidal, low wave energy, sumbergent (south coast slowly sinking)
* A concordant coastline with resistant Portland Limestone forming a protective stratum parallel to the sea.
* Less resistant Purbeck limestone and Wealden Clay lie behind the Portland, with resistant chalk further north.
* Portland limestone erodes very slowly, retreating landwards by marine undercutting and collapse to form a straight W-E coastline.
* At points where the Portland is weaker, erosion has broken through and then rapidly eroded out the softer strata laterally, creating a series of coves, e.g. Lulworth Cove and Stair Hole, with narrow openings, widening laterally parallel to the coast.
* In places such as Worbarrow Bay and St Oswald's Bay, lateral widening of coves led to them joining into a single bay, with remnants of the outer Portland left as a line of stumps parallel to the coast, e.g. Bull's Head in St Oswald's Bay.
* Straight coastline now formed by a concordant band of constant chalk.
107
Discordant coasts - Bantry Bay
* In Cork in the south west of the Republic of Ireland
Formed from less resistant Carboniferous Limestone
Beara Peninsula to the north formed from more resistant Devonian Old Red Sandstone and projects 35 km into the Atlantic Ocean.
* Sheep's Head Peninsula to the south formed from more resistant coarse sandstone, projects out 21 km.
* The high degree of indentation of Bantry Bay is not solely influenced by the relative resistance of rock types, but also the orientation of strata SW-NE means that they directly face high energy Atlantic waves driven by the prevailing SW wind.
* The Bay is also a product of sea level rise, since river erosion cut a low-relief river valley into Carboniferous Limestone, allowing the sea to flood inland and creating a ria at the start of the Holocene.
108
characteristics of Bantry bay
Submergent, secondary, mesotidal, high wave energy.
109
Types of dips example coastlines
* Horizontal (wave-cut platforms) = Southern Down, Wales.
* Low-angle Seaward - Hive Beach, Dorset.
110
What is a Dalmatian coast, and how does it form?
A coastline with long, narrow islands parallel to the coast, formed by folded rock ridges (anticlines) and valleys (synclines) being flooded by sea-level rise.
111
Where is a famous example of a Dalmatian coastline?
The Dalmatian Coast, Croatia.
112
What tectonic process shaped the Dalmatian Coast?
The collision of the African and Eurasian plates during the Alpine Orogeny (50 million years ago).
113
Fill in the blank: In Dalmatian coasts, sea level rise flooded ______ while ______ remained as long, narrow islands.
Synclines, anticlines.
114
What is a Haff coastline, and how does it form?
A coastline where a sand or shingle ridge forms parallel to the coast, trapping lagoons behind it.
115
Where is a famous example of a Haff coastline?
The Neman Haff, Baltic Sea (Kaliningrad, Russia → Lithuania).
116
Fill in the blank: Haff coastlines formed due to ______ waves pushing sediment landward after the last glacial period.
Constructive.
117
What is a UK example of a Haff coastline?
Chesil Beach (Dorset), which formed a tombolo connecting Portland Bill to the mainland.
118
What rock forms the outer layer of the South Dorset concordant coast?
Resistant Portland Limestone (parallel to the sea).
119
What happens when waves break through weaknesses in Portland Limestone?
Softer Purbeck Limestone and Wealden Clay erode rapidly, forming coves (e.g. Lulworth Cove, Stair Hole).
120
How did Worbarrow Bay and St Oswald’s Bay form?
Coves widened laterally and merged into one bay, leaving Portland Limestone remnants as offshore stumps e.g. bulls head in st oswalds bay
121
What rock type now forms the straight coastline behind these features?
Resistant chalk.
122
Fill in the blank: Wave refraction concentrates energy on ______ and disperses energy in a (convex shape) in ______, reducing indentation over time.
Headlands, bays.
123
What rock forms the soft bay at Swanage?
Wealden Clay (erodes rapidly).
124
What two headlands protect Swanage Bay?
1. Peveril Point (Jurassic Portland Limestone, projects 1 km).
2. The Foreland (Cretaceous Chalk, projects 2.5 km).
125
Why is Swanage Bay less deeply indented than expected?
It faces east, sheltering it from high-energy SW winds.
126
What rock type forms the soft bay at Bantry?
Carboniferous Limestone (less resistant).
127
What two resistant headlands surround Bantry Bay?
1. Beara Peninsula (Devonian Old Red Sandstone, projects 35 km).
2. Sheep’s Head Peninsula (Coarse sandstone, projects 21 km).
128
Why is Bantry Bay so deeply indented?
Its SW-NE rock orientation faces directly into high-energy Atlantic waves.
129
What historical sea-level change helped form Bantry Bay?
During the Holocene, rising sea levels flooded a low-relief river valley, forming a ria.
130
How does geological structure influence cliff profiles?
Through jointing, faulting, folding, and dip, which affect erosion rates and stability.
131
Fill in the blank: Cliff profiles are influenced by rock ______ and the ______ of rock strata.
Resistance, dip.
132
What are micro-features in coastal landscapes?
Small-scale features such as caves and wave-cut notches, controlled by faults and joints.
133
What are joints?
Fractures in rock created without displacement.
134
How do joints form in igneous rocks?
Cooling joints form when magma contracts as it loses heat.
135
How do joints form in sedimentary rocks?
By compression, stretching, or unloading after overlying rock is removed.
136
Why do joints increase erosion rates?
They create fissures that marine erosion (e.g., hydraulic action) exploits.
137
Case Study: How does jointing affect erosion in Stair Hole (Dorset)?
Heavy jointing in Purbeck Limestone (due to the Lulworth Crumple) causes it to erode faster than adjacent Portland Limestone.
138
Case Study: How does jointing affect Bantry Bay (Ireland)?
Heavily jointed Carboniferous Limestone erodes faster than adjacent sandstone, contributing to headland and bay formation.
139
What are faults?
Major fractures in rock with displacement, caused by tectonic forces.
140
Why do faulted rocks erode faster?
They are heavily fractured and broken, making them more vulnerable to marine erosion.
141
Case Study: How does faulting influence erosion in Bantry Bay?
A major SW-NE fault weakened Carboniferous Limestone, allowing rapid river and marine erosion, forming a ria.
142
What are folds?
Bends in sedimentary rock layers, created by tectonic compression.
143
What are the two main types of folds?
1. Anticlines (upfolds) 2. Synclines (downfolds)
144
Why does folding increase erosion rates?
Creates joints in anticline crests and compresses syncline troughs, making rocks more fissured and weaker.
145
What is dip?
The angle of rock strata in relation to the horizontal, caused by tectonic forces.
146
Fill in the blank: Dip affects cliff stability by influencing ______ and ______.
Erosion, mass movement.
147
What are micro-features?
Small-scale features such as caves, wave-cut notches, and blowholes.
148
How do micro-features form?
Erosion enlarges joints in areas of high structural weakness (e.g., caves in faulted cliffs).
149
Where are micro-features most commonly found?
Along faults and in rocks with high joint density.
150
Match the dip angle to its cliff profile:
151
Horizontal dip →
Vertical cliffs with notches
152
High-angle seaward dip (>45°) →
Low-angle cliffs, prone to rockslides.
153
Low-angle seaward dip (<45°) →
Overhanging cliffs, prone to rockfalls.
154
Landward dip →
Steep cliffs (70-80°), very stable.
155
Lithology
Rock type (igneous, sedimentary, metamorphic, or unconsolidated sediment).
156
Rate of Recession
The speed at which the coastline moves inland, influenced by lithology, mineral composition, structure, and cementation.
157
Clastic Rocks
Rocks made of sediment particles (clasts) cemented together. They are less resistant to erosion due to weaker bonds between grains. Examples include sandstone, limestone, and conglomerates.
158
Crystalline Rocks
Rocks made of interlocking mineral crystals, which makes them more resistant to erosion. Examples include granite, marble, and schist.
159
Mineral Composition
Some minerals are reactive and break down easily by chemical weathering, such as calcite in limestone. Others are inert and weather slowly, such as quartz in sandstone.
160
Rock Class and Resistance
Sedimentary rocks are generally less resistant due to their clastic nature, whereas igneous and metamorphic rocks are more resistant due to their crystalline structure.
161
Cementation and Weathering
The type of cement in sedimentary rocks affects erosion rates. Weak cements such as iron oxide and calcite dissolve easily, making these rocks more prone to erosion.
162
Structure and Weaknesses
Rocks with fissures, faults, joints, or porous structures are more vulnerable to erosion because they allow marine processes like hydraulic action to penetrate more easily.
163
Dip of Rock Strata
The angle of rock layers affects cliff stability. Seaward-dipping strata are unstable, whereas landward-dipping strata form more stable cliffs.
164
Erosion Rates by Rock Type
- Granite (igneous): 0.1 cm per year (very slow).
165
What is the erosion rate of Carboniferous Limestone?
1 cm per year (moderate).
166
How fast does young sandstone erode?
10 cm per year (fast).
167
What is the erosion rate of boulder clay (unconsolidated sediment)?
1-10 meters per year (very fast).
168
What are igneous rocks and why do they erode slowly?
Formed from solidified magma or lava (e.g., granite, basalt, dolerite, pumice). They erode slowly due to their crystalline structure.
169
What is the erosion rate of igneous coasts?
Less than 0.1 cm per year.
170
Why does newly formed volcanic rock erode quickly?
Newly formed lava and tuff (solidified ash) can erode up to 40 meters per year.
171
How are metamorphic rocks formed?
By heat and pressure altering existing sedimentary or igneous rocks (e.g., slate, marble, schist, gneiss).
172
What is foliation and how does it affect erosion?
Foliation is when crystals align in the same direction, making the rock weaker than igneous rocks.
173
What is the erosion rate of metamorphic coasts?
0.1–0.3 cm per year.
174
Why are sedimentary rocks less resistant to erosion?
They have weak bedding planes and are often heavily jointed due to compaction and pressure release.
175
How does sedimentary rock resistance vary with age?
Older sedimentary rocks are stronger due to deeper burial and more intense compaction.
176
What is the erosion rate of Carboniferous Limestone and young sandstone?
Carboniferous limestone erodes at 1 cm per year, while younger sandstone erodes at 10 cm per year.
177
What is unconsolidated sediment and why does it erode quickly?
It has not yet undergone lithification (turned into rock) and is very easily eroded.
178
What are examples of unconsolidated sediment?
Fluvial alluvium, glacial boulder clay, and aeolian loess.
179
What is drift geology?
Unconsolidated sediment that often overlies solid bedrock, making it highly vulnerable to erosion.
180
How does structural weakness influence erosion?
Joints, faults, and bedding planes make rocks more susceptible to marine erosion.
181
Why does the Holderness Coast erode so quickly?
It is made of glacial boulder clay, which is weak and retreats at 2–10 meters per year.
182
What is the mnemonic for rock resistance from slowest to fastest erosion?
Igneous → Metamorphic → Sedimentary → Unconsolidated ("I Must Study Urgently!").
183
What is the mnemonic for weakest to strongest sedimentary rock?
Boulder Clay < Sandstone < Carboniferous Limestone ("Big Soft Cliffs!").
184
Differential Erosion
Alternating strata of different resistance create complex cliff profiles. Less resistant rock erodes quickly, forming wave-cut notches, while resistant rock retreats slowly and may form overhangs.
185
Overall Cliff Recession Rate
Determined by the weakest rock layer, as it erodes the fastest and dictates cliff retreat.
186
Resistance to Marine Erosion
Some rock types erode more easily in the foreshore zone due to wave action, while others resist erosion and form benches.
187
Resistance to Weathering & Mass Movement
Rocks show different resistance levels in both the foreshore and backshore zones due to processes like chemical weathering and slumping.
188
Permeable Rocks
Allow water to pass through due to porosity (e.g., chalk) or numerous joints (e.g., Carboniferous limestone).
189
Examples of Permeable Rocks
Many sandstones and limestones (e.g., chalk, poorly cemented sandstone).
190
Why Permeable Rocks Are Weak
Water percolation exposes them to chemical weathering (e.g., carbonation in limestone, hydrolysis in feldspar granite).
191
Impermeable Rocks
Do not allow water to pass through. Examples: Clays, mudstones, most igneous/metamorphic rocks.
192
Springs Eroding Cliffs
Water accumulates in permeable rock above impermeable rock, forming a saturated layer. A spring forms where water emerges on the cliff face. Fluvial erosion from runoff weakens the cliff, reducing its angle.
193
Groundwater Removing Cement
Water moves through permeable sands but is blocked by impermeable clay. Groundwater flow removes cement, weakening rock structure. Weak, unconsolidated layers slump, causing cliff collapse.
194
Pore Water Pressure
Pore water pressure builds in the saturated layer, pushing rock particles apart. Reduces friction between grains, lubricating bedding planes. Leads to instability and mass movement.
195
Saturation Leading to Slumping & Sliding
Saturation adds weight and lubricates rock layers. Unconsolidated material slumps; consolidated rock slides. Creates a complex, uneven cliff profile.
196
Steep, Unvegetated Cliffs
Marine erosion dominates (waves remove debris). Little or no debris at the base (attrition and transport remove fallen material). Vertical or near-vertical profile.
197
Shallow-Angled, Vegetated Cliffs
Sub-aerial processes dominate (weathering, mass movement, surface runoff). Convex profile (curved shape). Debris accumulates at the base (marine erosion is too weak to remove it).
198
Why is vegetation important in stabilising sandy and estuarine coastlines?
Vegetation stabilises unconsolidated sediment, binds it together, and protects it from erosion. It plays a key role in dune and salt marsh succession.
199
How do plant roots help stabilise sediment?
They bind sediment together, making it harder to erode.
200
How do plant stems and leaves reduce erosion?
They cover the ground surface, protecting sediment from wave erosion, tidal currents, and wind erosion.
201
How does vegetation increase sediment accumulation?
Stems and leaves slow wind and water movement, encouraging deposition. Dead plants add organic matter (humus), improving soil stability.
202
Why is freshly deposited sediment a tough place for plants to grow?
It's exposed to high winds, extreme temperatures, saltwater, and poor nutrient availability.
203
Why does the coast have such a harsh environment for plants?
High wind speeds at low tide, high diurnal temperature range, saltwater submersion, saline sediment, rapid drainage, and lack of oxygen in saturated sediment.
204
What are pioneer plants?
The first plants to colonise fresh sediment, modifying the environment to support other plants.
205
How do pioneer plants modify the environment?
They stabilise sediment, add organic matter, retain moisture, contribute nutrients, and provide shade.
206
What is plant succession?
The process where different plant communities gradually colonise an area over time, leading to a stable ecosystem.
207
What is a seral stage?
A step in plant succession where new plants colonise, modifying conditions for the next stage.
208
What is a climatic climax community?
The final stage of plant succession where the ecosystem reaches stability, in balance with climate and soil conditions.
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What kind of plants colonise bare sand?
Xerophytic plants, adapted to dry conditions.
210
What is plant succession on sand called?
Psammosere.
211
How do embryo dunes form?
Sand accumulates around obstacles like seaweed, driftwood, or litter.
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What happens to embryo dunes over time?
They are colonised by xerophytic pioneer plants like sea couch grass, lyme grass, saltwort, and sea rocket.
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What comes after the embryo dunes?
Fore dunes form as more plants colonise and stabilise the sand.
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Why is marram grass so well adapted to dunes?
1 - Waxy leaves limit water loss and resist sand abrasion. 2. Roots grow up to 3m deep to reach water 3. Stems grow up to 1m per year to avoid burial
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What happens when marram grass stabilises the sand?
The dune grows into a yellow dune, which is mostly sand.
216
How does the dune change from yellow to grey?
Marram grass and sedge die, adding humus to create soil. Grey dunes develop with plants like gorse, red fescue, heather, and creeping willow
217
What kind of plants colonise muddy estuarine areas?
Halophytic plants, adapted to salty conditions.
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What is plant succession in saltwater called?
Halosere.
219
Why are estuarine areas ideal for salt marshes?
They are sheltered from strong waves, allowing fine sediment like mud and silt to deposit. Rivers supply sediment, and tides bring more.
220
What is flocculation?
A process where fresh and saltwater mix, causing clay particles to clump together and sink.
221
What are the first plants to colonise mudflats?
Algae like blue-green algae and gutweed.
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How do these algae help stabilise mud?
They bind mud, add organic matter, and trap sediment.
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What is the next seral stage of salt marsh succession?
Low marsh plants like glasswort and cordgrass, which can survive daily tidal flooding.
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How does sediment accumulation change the salt marsh?
It raises the marsh, reducing the time it's submerged, allowing more plants to colonise.
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What plants colonise the higher salt marsh?
Sea aster, sea lavender, sea thrift, and scurvy grass.
226
Why does salt content decrease in higher marsh areas?
Rain washes salt out of the soil, allowing land plants to grow.
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What is the climax community in UK salt marshes?
Usually deciduous oak forests or pine forests in northern Scotland.
228
What are blowouts?
Gaps in dunes caused by storms eroding sections of yellow dunes via wind or wave action.
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How do dunes recover from blowouts?
Over time, new deposition and recolonisation of vegetation rebuild the dunes.
230
What happens if a blowout exposes wet sand?
A marshy dune slack forms, supporting freshwater plants like marsh orchids.
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What are creeks in salt marshes?
Small river distributaries that flow through the marsh, transporting water.
232
What stabilises marine sediment in tropical regions instead of salt marshes?
Mangrove swamps.
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What happens to the dune’s soil as it develops?
Rain washes salt away, making it less saline.
Rain washes salt away, making it less saline. Nutrients and moisture increase, allowing non-xerophytic plants to grow.
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What is the final stage of dune succession?
A stable climax community with trees like bramble, pine, and birch
