Coastal Systems AW Flashcards
What are the 4 factors of dynamic equilibrium in a coastal system?
-supply of sand
-the energy of waves
-changes in sea level
-the location of the shoreline
Explain dynamic equilibrium in terms of waves and beach erosion
The summer has more constructive waves, which have a stronger swash than backwash so more material is deposited, the beach grows and gets steeper.
The winter has more destructive waves so the swash is weak and the backwash is strong so more erosion and the beach shrinks.
Define dynamic equilibrium
A system is subject to continuous change which counteracts the changes to stay within set parameters
Whats negative feedback ?
The system counteracts the change, lessening/ reversing it’s effect
Whats positive feedback ?
System reacts and accelerate the change and effect on the environment
What is an example and positive feedback?
The suns rays warm the earth melting ice in the arctic/antarctic (which has high albedo effect and reflects sun’s rays cooling the earth) increasing the size of the dark oceans (which have low albedo and absorb more heat) warming the earth melting the ice faster
What is an open system ?
- add example
A system allows mass and energy to flow across the system boundary.can be flow of matter.
- the sun
- the hydrosphere
- the coast
What is a closed system ?
-add example
The system allows energy flow across system boundaries, but no flow of matter.
- the earth
- the geosphere
What is a littoral cell ?
(Sediment cell)
A section of coastline where sediment is recycled but not lost or added to
Define sediment budget
The amount of sediment on a beach.
(The net value between amount of input and output)
What is a positive beach budget ?
Excess sediment on the beach
What is a negative beach budget ?
When there is a sediment deficit on the beach
What is a neutral sediment budget ?
When there is no difference between the input and output quantities of sediment.
What are some inputs of a sediment budget ?
Landward Material inputs
- Mass movement
- Cliff erosion
Marine inputs
- Longshore drift
- Wave deposition
What are some outputs of a sediment budget in a simple beach system ?
Landward Material outputs
- Sand dune development
Marine outputs (flows)
- Waste removal
- Longshore drift
What is the store in a simple beach system sediment budget ?
The Beach
Give an example of negative feedback
Cliff erosion leads to slumping, so cliff material falls in front of the cliff, protecting it from erosion until the waves can remove and erode the slumped material
Give an example of negative feedback
Cliff erosion leads to slumping, so cliff material falls in front of the cliff, protecting it from erosion until the waves can remove and erode the slumped mayerial
Give a beach example of a positive feedback loop
Waves remove vegetation from rocks and cliffs, so there isn’t anything to protect them. The cliff erosion speeds up.
What is a penantuala ?
Land that sticks out and is surrounded by sea on 3 sides
Wind is a transfer of energy via the atmosphere. How is wind created ?
Via a pressure gradient. Air moves from areas of high pressure to areas of low pressure. The larger the difference in pressure, the faster and more powerful the wind.
What’s the average global atmospheric pressure ?
1 bar or 1000 millibars
What causes different pressures ?
The sun heats air, hot air rises, creating low pressure.
How large are the pressure differences in the atmosphere ?
There can’t be large differences in pressure because gas moves and there is no physical barrier stopping it. 980mb is very low pressure, causes strong winds
Define pressure gradient
How fast the pressure changes in different areas
What is atmospheric pressure ?
The weight of the atmosphere on the ground
What are wave features
Add diagram
Describe a constructive wave
Strong swash and weak backwash so material is deposited on the beach, making it bigger and steeper
In the summer, mostly
Low wave height, long wavelength - long rolling waves.
Describe a destructive wave
High energy waves, tall in height.
Weak swash and strong backwash, so material is transported down the beach.
Mainly in the winter.
What is wave refraction?
. Convergent and divergent
When waves are around a headland they tend to bend, as waves approaching a headland hit shallower waters sooner than the rest of the wave ( in the bay which is in deeper water)
The wave by the headland in shallower water experiences friction with the sea floor - slowing. The edges of the wave move faster and the wave converges around the headland.
In the bay the opposite happens and the edges of the wave are in shallower water nearest the headland and friction slows them (slower relative to wave in deeper bay). Thile wave diverges into the bay.
What is Swash aligned ?
Where the waves hit the beach at 90°
What is drift aligned ?
Where the prevailing wind is at a significant angle to the beach so waves hit the beach at an angle and cause longshore drift up the beach
What’s a discordant coastline?
Where the coast is made up of bands of multiple types of rock perpendicular to the coast (of different densities leading to the formation of headlands and bays)
What’s a concordant coastline?
Beds of rock are parallel to the coast so the coastline has the same type of rock along the coast.
What are tides caused by?
Tides are caused by the gravitational pull of the sun and moon.
The moon has the greatest influence due to distance, oceans closest to the moon have an outward bulge, causing high tides ( low tides is the draining of water from areas)
What is a neap tide?
What causes them?
The highest low tide and the lowest hight tide in a year.
Caused when the sun and the moon are at right angles and interfere with each other.
What is a spring tide?
What causes them?
Highest high tide and the lowest low tide
Highest tide where the earth is between the moon and sun.
How long is between high and low tide?
How many tides are there per day?
There’s 6 hours between high tide and low tide.
4 tides per day, 2 high and 2 low tides.
Define tidal range
The difference between high tide and low tide
What is macrotidal?
When the tidal range is larger than 4 metres
What is mesotidal?
When the tidal range is between 4 and 1.8 metres
What is microtidal?
When the tidal range is less that 1.8 metres
What influences tides?
. Gravitational pull of sun and moon
. Weather conditions
. Ocean bed
. Rivers and shape of coastline
What causes currents?
Water in the ocean is different densities in different areas, causing currents as high density water moves to low density areas.
What causes different water densities in the ocean?
. Saltiness of water (from rocks with sodium dissolved
. Temperature
What are longshore currents caused by?
Longshore currents are caused by prevailing winds hitting at a non 90° angle
(A near shore current that is very localised and small scale)
What’s an upwelling current?
Where water comes up to the surface.
(A near shore current that is very localised and small scale)
What is a rip current
Rip currents are strong, localised underwater currents that occur at some beaches. Formed when a series of plunging waves cause a temporary build up of water at the top of the beach, met with resistance of breaking waves the backwash is forced under the surface.
What is the gulf stream?
A large current that comes up from Mexico, the water is warm and less dense. Moves 4 billion cubic feet of water per second.
What is the great ocean conveyor belt?
Created by the sinking and falling of ocean currents. It transfers heat and takes 1000 yes for water to move through the conveyor belt.
What is a storm surge?
When meteorological conditions giving rise to strong winds can produce much higher water levels than those at high tide.
Very low pressure systems (e.g. hurricanes) take the weight of the atmosphere off the ocean allowing every water molecule to take up more space, ocean rises.
Where is the back shore zone?
The area between the highwater mark and landward limits of marine activity (changes only occured during storm activity)
Where’s the foreshore zone?
Area between low water mark and high water mark. The most important place for marine processes.
Where’s the inshore zone?
The area between the point where waves don’t have any affect on the land below and the low water mark.
(Foreshore + inshore = Nearshore)
What’s the Nearshore zone and the subsections?
Area seaward from the high watermark to the area where waves begin to break.
Including:
. Swash zone
. Surf zone
. Breaker zone
What’s the swash zone?
Subsection of Nearshore zone. Area where turbulent layer of water washes up on the beach after the wave breaks.
What’s the surf zone?
Subsection of Nearshore zone. Area between the point where the waves breaks and where the waves moves up the beach as swash in the swash zone.
What’s the breaker zone?
Subsection of Nearshore zone. Area where the waves begin to break when approaching the beach (usually water depth is 5-10 metres)
What’s the offshore zone?
Area past the point where waves stop impacting the sea bed below, deposition of sediment is limited.
What are Sediment cells?
Sediment is moved around distinct areas/ cells, normally separated by a distinct feature e.g. a headland. There regarded as a closed system as no sediment is lost or gained (theoretically). They are very large and may have sub cells within them.
What are the problems with the concept of sediment cells?
In theory the sediment is lost or gained but in reality small bits of sediment are easily transferred to different cells.
What is a fetch?
The fetch is the uninterrupted distance that wind blows over a body of water from one obstacle to another, in the same direction.
What effect does the fetch have on waves?
Work is done as wind blows over the water called fictional drag, the longer the fetch the bigger and more powerful the waves are (due to more energy being transferred).
How far down do waves cause movement?
Waves cause surface water movement and 5 - 10 metres down water doesn’t really move
What’s motion do waves move in?
Waves are just energy passing through water in circular motions. The water stays in pretty much the same place as the wave moves. This motion causes air to get trapped making it less dense than the rest of the water so it stays on top.
What happens to the orbital motion of waves at the shore?
At the shore the water gets shallower and the orbital motion is broken/ disrupted by the sea floor. The bottom of the wave slows due to friction forcing the crest higher, causing it to crash down. The wave breaks.
What are datums?
Scientists use datums as a normal and use it as a reference to see how much water levels rise and fall
What causes currents?
They are driven by wind, tides, shape of land and temperature
How do you measure currents?
Main components are speed and direction, put an object in the ocean and record how long it takes to get to a certain place
How do you measure tides?
Air acoustic and pressure systems to record changes in water levels
Why do people study tides and currents?
Need knowledge of them to
. Aid navigation
. Keep people and the environment safe
. Need to know the water levels for boats to pass under bridges
What is the intertidal zone?
The zone between high and low tides, it’s a harsh and unforgiving habitat.
What are the 4 subsections of the intertidal zone?
. The spray zone
. High intertidal zone
. Mid intertidal zone
. Low intertidal zone
Describe the spray zone.
Mostly land, rarely submerged in ocean (only very high tide or storms), wet from waves and wind blown spray
Life like litchens and periwinkle snails
Describe the high intertidal zone.
Out of water in long stretches but submerged during daily high tides.
Life like crabs, seaweed, barnacles
Describe the mid intertidal zone.
Submerged other than low tide.
Life like muscles, snails, sea urchins
Describe low intertidal zones.
Submerged and only exposed during lowest spring tides (twice a year)
Life like crabs, urchins, kelp, sea stars
What can disrupt dynamic equilibrium?
Physical: storms
Human: swa walls, groynes, gabions, mining, people using the beach
What’s the difference between erosion and weathering?
During weathering rocks stay in situ (same place).
List 4 types of erosion
Hydraulic action
Abrasion
Attrition
Solution (corrasion)
What two processes wear away the coast?
Marine processes
Sub aerial process
What are marine processes
Hydraulic action
Abrasion
Attrition
Solution
Wave quarrying
Wave Cavitation
What is wave quarrying?
What is cavitation?
Wave quarrying - Breaking waves trap air, water compresses air into any gaps in the rock creating enormous pressure, weakening the cliff, chunks can be easily removed.
Cavitation - waves vibrate the cliff and break off chunks.
Define weathering
The wearing or breaking down of rocks while they are in place
What is Biological weathering
Weathering from nature and animals.
E.g. from roots of a tree getting into cracks in rocks, widening them and breaking off chunks. Or a rabbit burrowing a hole.
What is mechanical weathering
Physical processes of weathering.
Freeze thaw- water gets into cracks top freezes first creating a ‘plug’, the water below freezes, expanding and can’t expand up, creates pressure on the crack widening it.
Wetting and drying - porous rocks/clay. The rocks expand when wet and when dry they contract causing cracks to form
Salt Crystalisation - salt crystals are deposited in cracks and they accumulate overtime applying pressure to the crack
What is chemical weathering
Carbon dioxide dissolves in rain making it slightly acidic- can react with rocks like limestone - weathering them.
What is soil creep?
A very slow movement on a gentle slope when soil expands and contracts as it wets and dries. When it drys it contracts vertically and when in wets it expands at right angles.
Define landslides
Material falls down along the ground
Define rockfall
Landfalls vertically
Define mudflows
Saturated soil flowing down a slope
Define rotational slumping
Heavy rain it absorbed by loose material that makes up the cliff (usually glacial till) . The cliff face becomes heavier and eventually it separates from the material behind. Lubricated by the rain. Falls in a rotational curved motion
What factors effect the rate of erosion at the coast?
. Geological structure (cracks, rock strata, bedding planes)
. Presence of a beach (they absorb wave energy, protects cliffs from erosion)
. Sub aerial processes ( weathering and mass movement weaken cliffs)
. Waves and fetch (size and power of waves)
. Rock type (physical strength)
. Coastal management (can slow erosion)
What is a discordant coastline?
Coastlines with different rocks perpendicular to the coast, hard and soft.
Landforms like headland and bays.
What is a concordant coastline?
One type of rock parallel to the coastline.
How is a wave-cut platform formed
A wave-cut notch is created by erosional processes like hydraulic action and abrasion.
The notch becomes larger and the cliff is unstable and collapses.
Cliff retreats inland.
Eroded material is transported away.
Leaving a wave-cut platform.
Processes repeat.
(Wave cut platforms slow cliff erosion)
Describe longshore drift
The prevailing wind cause waste to hit the beach at an angle.
The wave carries sediment transporting it up the the beach, gravity pulls the water back down the beach at a right angle (backwash). This causes the Sediment to move up the beach in a saw tooth pattern.
What are Aeolian processes?
The transportation and deposition of sediment via wind.
Describe three physical weathering processes.
-Freeze thaw
water gets to cracks in the rock.
top layer freezes first as it’s more exposed
•the bottom layer of water then freezes and expands (ice is 9% bager time water as it traps air) and can’t expand up because top ice blocks it in so expands widening the crack.
the ice then thaws and the water doesn’t fill the large cracks now. so more water fills. Process repeates
-Salt Crystalisation.
.Salt crystals are deposited in cracks, over time the Salt accumulates and applies pressure to the crack.
-wetting and drying of rocks
water absorption to (clay rich rocks or porous rocks. Cause them to expand then contract. When they dry, it causes cracks to form.
What are the 4 main types of mass movement?
Creep- soil creep
Flow- mudflow
Slide- rock slide, rotational slumping
Fall- rockfall
Factors that can cause landslips and slumping.
Rock type - bedding planes, competence of rocks (high/strong=slipping, low/weak=slumping), weathering weakening rocks.
Slope angle- the steeper the more likely to fall.
Water- adds weight, lubricant.
Human contributions- building on a slope, removing vegetation (which intercepts water and binds soil).
What’s soil creep/ solifluction
Very slow continuous movement of individual soil particles down slope in the presence of water and weathering processes.
Particles change size when they’re freeze and thaw
Its very slow over thousands of years solifluction is freezing and thawing and soil creep is wetting and drying
What is mudflow
Is a form of mass movement where large quantities of fine material flow downhill, soil become saturated and excess water stays on the surface, it’s very fluid and flows down
What are landslides
A form of mass movement on Cliffs made from softer rocks or deposited material, like glacial till, the slip is as a result of failure within the cliff when lubricated usually following rainfall
It’s a fast and short movement
What’s run-off
Water running over the surface of land, it’s presence aids mass movement.
What’s rockfall
A form of mass movement where individual rocks fall by themselves from the air very fast and short movements. It’s dry.
What’s land slip/slumping
A form of mass movement where soft material is on more resistant material and moves down in a rotational movement
What’s the difference between weathering and mass movement
During weathering the material stays in situ, but in mass movement it moves and is caused by Gravity.
Describe the difference between back wash on a sandy beach and a pebbley beach
Sandy beaches have a shallow gradient than stony. As sandy beaches can’t support a stepping gradient
Sandy beaches have less percolation (less water to seep into the sand so there is a strong backwash)
Stony beaches have high percolation, so more water seeps into the beach, so a weaker backwash and a steeper beach.
What’s a berm
Beach ridges built be constructive waves
What’s a runnel
When a ridge forms at the low watermark, the water can’t flow over the bump so the water flows up the beach.
How’s the spit formed?
1.The prevailing wind hits the beach at an angle causing the swash to go up the beach as an angle carrying sediment and then down the beach perpendicular as backwash
2. this causes longshore drift carrying sediment up the coast then there’s a sharp bend in the coastline and sediment is to deposited offshore
3. shallow water gives the beach support and the beach builds up and spit extends to the sea
4. due to prevailing wind the beach recurves parallel with the prevailing Wind called a hook
What is a compound spit?
This is where the spit has multiple hooked ends and recurves. After each hook, there are changing conditions, which causes the spit to grow further out, and then the prevailing wind causes it to hook and recurve again.
For example, increased wind strength, reduced water depths, Leeward of the spit, reduced river flow, and increased river load of sediment.
What are cusps?
Semicircular shapes depressions which form when waves break directly onto the beach and the swash and backwash and strong
What is a offshore?
At high tide, water gets deeper (5 - 10m) where not much water movement occurs, and is a low energy environment, so sediment is dropped. This forms an offshore bar.
What’s a ridge?
areas of the foreshore that are raised above the adjacent shore which dips into a runnel
What is a tombolo?
A tombolo is formed when a spit connects the mainland coast to an island. A spit is a feature that is formed through deposition of material at coastlines. The process of longshore drift occurs and this moves material along the coastline.
(A beach connecting and island to land)
What’s a barrier beach (same as a bar)
A sand ridge that’s above the surface of the sea and runs parallel to the shore across a lagoon. Connecting the two sides ( a spit that meets both sides)
What’s a barrier island
When a barrier beach is completely separated from mainland
What do dunes need to be formed?
○ Dry, fine sand
○ Accommodation land
○ Wind - offshore constant strong wind ( so it can suspend and move or move it along the ground)
How is a sand dune formed?
- Sand Supply & Transportation
○Sand is transported by the wind through saltation (bouncing), creep (rolling), and suspension (lifting).
○A steady wind supply and a large dry sediment source, such as a beach, are essential for dune formation.
- Obstacle & Deposition
○When wind encounters an obstacle (e.g., driftwood, vegetation, or a rock), its velocity decreases, causing sand to be deposited.
○Over time, the accumulation of sand builds up into small mounds.
How do dunes grow and mature?
As more sand accumulates, dunes grow and shift inland due to continued deposition and wind transport.
Vegetation, such as marram grass, stabilizes the dunes by trapping sand and reducing wind erosion and roots bimd the dune together.
What are the different dunes as they mature further from when they are formed?
- Embryo dunes – Small dunes forming near the high-tide mark.
- Fore dunes – Slightly larger dunes stabilized by hardy pioneer plants like marram grass.
- Yellow dunes – Larger dunes with more vegetation coverage.
- Grey dunes – More mature dunes, covered with humus and shrubs.
- Climax community – A stable environment with trees, such as pine or oak.
What are embryo dunes?
Embryo dunes – Small dunes forming near the high-tide mark.
What are fore dunes?
Fore dunes – Slightly larger dunes stabilized by hardy pioneer plants like marram grass.
What are yellow dunes?
Yellow dunes – Larger dunes with more vegetation coverage.
What are grey dunes?
Grey dunes – More mature dunes, covered with humus and shrubs
What Key Factors Influencing Dune Formation?
Wind strength and direction – A strong onshore wind moves more sand.
Sediment supply – More sand availability promotes dune growth.
Vegetation – Plants help stabilize dunes and prevent erosion.
Where are mud flats located?
Usually found in areas where tidal water flows slowly, e.g.sheltered bays, estuaries, rias, and along gently shelving coasts
How are mud flats formed?
A mixture of very fine silt from tidal waters and from Rivers is deposited, causing a buildup of mud layers called mud flats. mud flats are covered at high tide and exposed when it drops.
What’s the process of mudflat formation
- Sediment Deposition: Tidal currents deposit fine sediments in areas of low energy, such as sheltered shorelines or estuaries, where the water slows down as the tide comes in and out.
- Intertidal Zones: These areas, located between the high and low tide marks, are particularly important in mudflat formation. When the tide retreats, water velocity decreases, allowing the fine particles to settle on the surface.
- Vegetation Growth: Over time, small plants or saltmarsh vegetation may begin to colonize these mudflats, trapping additional sediment. This stabilizes the mudflat and promotes further deposition.
- Erosion and Reworking: While mudflats can be eroded by storm surges or strong tidal currents, over time, they can build up again as sediment is continually deposited.
How do saltmarshes form?
Saltmarshes form from mudflats as salt-tolerant plants (halophytes) begin to colonize the area. These plants stabilize the sediment with their roots, reducing erosion and allowing more sediment to accumulate. Over time, the build-up of organic matter from decaying plants enriches the soil, promoting further plant growth and turning the mudflat into a saltmarsh.
Where do salt marshed and mud flats form?
In areas that are well sheltered creeks, inlets, etuaries and behind spits and artificial sea defences, as this is a low energy area so tidal water flow slowly depositing fine sediment.
What are some depositional features?
○ a spit
○ a bar
○ tombolo
○ offshore bar
How do tombolos form?
Form where there is a wave shadow behind a near shore island, behind the island is a low energy area, so deposition occurs. (Slowing longshore current as well)
Over time, enough sediment deposits connecting mainland to island.
What’s an offshore bar, and how is it formed?
An offshore bar is a submerged or partially exposed ridge of sand that forms parallel to the coast due to wave action. Waves pick up and deposit sediment offshore, creating a ridge. Swash and backwash move sediment, and storms can enhance bar formation. Offshore bars help reduce wave energy and may evolve into barrier beaches or spits over time.
What is a beach?
A beach is an accumulation of deposited sediment where land meets the sea.
What’s a storm beach?
A steep beach formed by large waves during storms, depositing coarse material at the high tide mark.
Why do sand beaches leave a gentle gradient?
Sand has small particles that allow less percolation, leading to stronger backwash and more material being carried down the beach.
Why do shingle beaches have steeper gradients?
Shingle allows more percolation, reducing backwash strength and limiting sediment transport.
What are berms, and how do they form?
Berms are ridges of sediment formed by constructive waves marking successive lower tides.
What are cusps on a beach?
Semi-circular depressions formed where swash and backwash meet directly.
How does a spit form?
Longshore drift moves sediment along the coast, and a change in coastline shape causes deposition, forming a spit.
What causes a spit to develop a recurved end?
A second, stronger wind or wave direction changes deposition patterns.
What are the main threats to salt marshes?
Rising sea levels, human activity, pollution, and climate change.
What does the formation of Salt Marshes need ?
Occurs in sheltered, low-energy environments.
Requires accumulation of fine sediments and organic material.
Pioneer species (salt-tolerant plants) help stabilize sediment.
Vegetation succession leads to marsh development.
Detailed Process of Salt Marsh Formation:
A low-energy coastline or estuary is needed to allow sediment to settle.
Fine sediments (such as silt and clay) are deposited due to slow water movement.
- Pioneer Species Colonization:
Salt-tolerant plants (e.g., Spartina) establish stabilizing the sediment.
As plants grow, they trap more sediment, raising the marsh’s height. Over time, more complex vegetation replaces pioneer species, leading to full marsh development.
Define flocculation
Clay particles stick together and are deposited
What conditions are needed for the formation of mud flats?
○ sheltered coastline
○ low lying
○ submerged at high tide
○ composed of silt and clay
What is eustatic change?
A global change in sea level caused by glacial amd interracial periods, during glacial periods more water is stored on land as ice so sea levels fall, during interracial periods sea levels rise due to ice melting and thermal expansion.
What is a Ria ?
A steep sided V-shaowd valley formed by rise in sea levels.
It’s a funnel-shaped estuary that occurs at a river mouth and is formed by the submergence of the lower portion of the river valley
What is a fjord ?
A glacier is formed during a glacial period, and as the glacier moves, it forms a U-shaped valley as it erodes the land. then a warming period (integracial period occurs) leading to glacier melting, causing eustatic sea level rise. This leads to flooding of glacial Valley, forming a fjord.
What is isostatic change?
Localised relative change in sea level caused by the land moving up or down in relation to the sea. Caused by loading or unloading of ice. Isostatic rebound / recovery is greatest over Scotland because that’s where most of the ice was the land of Scotland is rising approximately 4 to 20 mm per year or it’s a land in the south is sinking.
What is isostatic rise?
Isostatic fall is the lowering of land or due to isostatic adjustment, often caused by the redistribution of mass, such as glacial melting or sediment deposition. (Sea level rises in relation to land).
What is isostatic rise?
Isostatic rise is the uplift of the Earth’s crust due to the removal of a heavy load, such as melting glaciers or erosion, leading to rebound. Causes sea level to fall relative to the land.
What are raised beaches ?
Emergent landforms, former wave cut platforms which are now raised above currency level they are formed when Isis static recovery exceeds sea level.
What are submergent landforms
Associated with rising sea level, for example, rias, fjords and deltas. They are from when a landform is submerged due to rising sea levels
What are emergent landforms?
Due to fall in sea level, for example, raised beaches.
How would rising sea levels affect the UK
○ Land below 5 m would be at risk from flooding
○ saltwater would be polluted by fresh water
○ sea levels would rise by 10 to 20 cm in the south, and sea defences would need to be provided or rebuilt.
How does tectonic activity change sea levels ?
The building of mountains in oceans, from tectonic plates moving together, causes sea level rise due to the ocean basin becoming smaller, causing Eustatic rise.
However, mountains forming on land or getting bigger cause ocean bases to get bigger so sea levels fall (Eustatic fall).
What is solifluction?
Very slow movement of soil particles in periglacial environments.
Solifluction typically occurs in regions with frozen ground.
Define rockfall.
A rapid movement of material down a slope.
Rockfalls can be triggered by various factors such as earthquakes or weathering.
Define mudflow.
Saturated Earth and mud flow downhill, over weak bedrock.
Mudflows often occur after heavy rainfall or volcanic activity.
What is soil creep?
Very slow movement of soil particles downhill.
Soil creep can be difficult to detect but can lead to significant landscape changes over time.
Abrasion.
The process of wearing away material due to friction or impact.
Abrasion can occur in various environments, including rivers and coastlines.
Attrition.
The process where particles collide and break down into smaller pieces.
Attrition is common in river systems where sediments are transported.
What does the term ‘hydraulic action’ refer to?
The process of erosion caused by the force of moving water.
Hydraulic action is particularly effective in riverbanks and coastal areas.
Define progradation
Dunes building out to sea
List dunes from start to maturity.
○ embryo dune
○ fore dune
○ yellow dune
○ grey dune
○ mature dune
What is a raised beach?
An emergent landform
A raised beach is a beach at a level above the shoreline, where high tide no longer reaches. It is formed due to changes in sea level (eustatic change) or land uplift (isostatic rise).
How is a raised beach formed?
A raised beach is formed by wave action when it is close to the waterline. Later, a change in sea level (eustatic change) or land uplift (isostatic rise) causes the land to be pushed out, leaving the beach elevated above the shoreline.
What factors Control Sea Level?
- Eustatic (Global) Changes:
○Thermal expansion (warmer water expands).
○Glacial and ice cap melting (adds water to oceans).
○Tectonic activity (alters ocean basin capacity). - Isostatic (Local) Changes:
○Isostatic rebound (land rises after ice melts).
○Isostatic sinking (land sinks due to sediment build-up).
○Tectonic uplift/subsidence (earthquakes and movements shift land levels). - Other
○ Human activity (groundwater extraction, dam construction).
Describe the stages of Eustatic and Isostatic sea level change.
Stage 1: Eustatic Fall
○Climate cools → More snow & ice stored on land
○Less water in the sea → Sea level falls
Stage 2:** Isostatic Movement**
○Ice weight pushes land down
○Causes land subsidence → Sea level rises relative to land
Stage 3: Eustatic Rise
○Climate warms → Ice melts → Water returns to sea
○Sea level rises → Floods low-lying areas
Stage 4: Isostatic Rebound
○Ice melts → Land slowly rises back up
○Creates emergent features (e.g., raised beaches)
Describe the greenhouse effect.
- The Sun emits energy in the form of shortwave radiation, which passes through the Earth’s atmosphere and reaches the surface.
– The Earth’s surface absorbs this energy, warms up, and then radiates heat back as longwave infrared radiation.
– Greenhouse gases like carbon dioxide (CO₂), methane (CH₄), water vapor (H₂O), absorb and re-radiate some of this heat, preventing it from escaping into space.
– This trapped heat keeps the Earth’s temperature at an average of around 15°C, making life possible.
What are natural factors that cause variegation in the climate?
○ el niño effect
○ volcanic eruptions (particles emmitiled into the atmosphere blocking the suns radiation, causing short-term cooling (volcanic winter))
○ milankovitch cycle (small variations in the earths orbit around the sun.
What to humans do that enhance the greenhouse effect?
Burning Fossil Fuels – Coal, oil, and natural gas release CO₂ into the atmosphere.
Deforestation– Fewer trees mean less CO₂ is absorbed, increasing greenhouse gas levels.
Agriculture – Livestock produce methane (CH₄), and fertilizers release nitrous oxide (N₂O).
Industrial Processes – Factories emit greenhouse gases like CO₂, CH₄, and fluorinated gases.
Waste Disposal – Landfills release methane from decomposing waste.
Transportation – Cars, planes, and ships burn fossil fuels, adding CO₂ to the air.
Urbanization – Expanding cities lead to increased energy use and deforestation.
What’s the difference between mitigation and adaptation?
Mitigation is to stop the problem, and adaptation is where practices are modified to suit new conditions
What are four options/ catorgari3s if coastal management?
○ hold the line- maintain and continue existing defences
○advance the line- build new coastal defences
○managed retreat-allow shoreline to erode - managed to minimise damage.
○ do nothing deal with erosion as it happens
What is a cost benifit analysis?
A cost benefit analysis is carried out before a coastal management project is given to go ahead. Costs of forecast then compared with the expected benefits when costs exceed benefits it’s unlikely to be given permission to go ahead.
What is beach nourishment?
Edition of sandal bubbles to an existing beach to make it higher or wider.
What are advantages of beach nourishment?
○It’s relatively cheap and easy to maintain
○it looks natural and blends with the existing beach
○increases tourist potential by creating a bigger beach
What are disadvantages of beach nourishment?
Constant maintenance because of natural processes of erosion and longshore drift as these aren’t combatted in anyway
What is Cliff regrading and drainage?
Cliff regrading reduces the angle of a cliff to help stabilize it as the steeper the cliff easier erosion impacts it.
Drainage removes water and prevents landslides and slumping.
What are advantages and disadvantages of cliff regrading and drainage?
Advantages
Can be effective on clay or loose rocks where other methods won’t work and drainage is cost-effective
disadvantages
Degrading effectively causes the cliff to retreat and drainage Cliffs can dry out and lead to collapse and rock Falls
What is Dune stabilization?
Murram grass can be planted to stabilize dunes as the roots and vegetation stabilise it. Areas can be fenced in to keep people of newly planted dunes
What are advantages and disadvantages of dunes stabilization?
Advantages
Maintains a natural coastal environment that provides important wildlife habitats and is relatively cheap
Disadvantages
It’s time consuming to plant Marron grass and people may respond negatively to being kept off certain areas
What is Marsh creation?
A form of managed retreat by allowing low-lying coastal areas to be flooded by the sea the land then becomes a Salt Marsh
What are advantages and disadvantages of marsh creation?
Advantages
It’s relatively cheap, creating a natural buffer to powerful waves and an important wildlife habitat.
Disadvantages
Agricultural land is lost. Farmers or landowners need to be compensated.
What are soft engineering coastal management techniques?
○ beach nourishment
○ cliff regrading and drainage
○ dune stabilisation
○ marsh creation
○ reprofiling
What is reprofiling a beach?
A form of soft engineering that reduces the steepness of the beach, this causes a weaker backwash, stronger swash -> constructive waves.
Why is soft engineering unsustainable?
○It can be expensive over time as it has to be redone
○machinery for smth like beach nourishment causes pollution
What are the reasons not to protect a stretch of coastline?
○ sometimes cheaper for the local government or Council to buy the land and not protect it
○ don’t have the budget or money for it
○ it’s an unpopulated area
○ by protecting one area of the coast it may starve areas down the coast
○ some people buy The Land knowing it’s not going to be there as it’s cheap land for example businesses like a caravan park
What are some hard engineering coastal management techniques?
○ groynes
○ sea walls
○ rock armour (rip rap)
○ revetments
○ offshore breakwater
What are groynes?
Timber or rock structures built at right angles to the coast to stop longshore drift by trapping sediment and building up the beach.
What are the advantages and disadvantages of groynes?
Advantages
Not too expensive
Works with natural processes to build up the beach
Disadvantages
Staves beaches down the coast
Can be unattractive
What are sea walls?
Stone or concrete walls at the foot of a cliff or at the top of the beach they usually have a curved face to reflect waves back to the sea.
What are the advantages and disadvantages of sea walls?
Advantages
Effective and often have a promenade for people to walk along
Disadvantages
They reflect wave energy instead of absorbing it
Expensive to build and maintain
Unattractive
What is rock armour/ rip rap?
Large rocks placed at the foot of a cliff or at the top of a beach. Forms a permeable barrier to the sea breaking up the waves but allowing some water to pass through.
What are the advantages and disadvantages of rock armour/rip rap?
Advantages
Relatively cheap
Easy to construct and maintain
Disadvantages
Can be dangerous to ppl climbing over
Looks unnatural, especially non local rocks lock geological out of place
What are revertments?
Sleeping wooden or concrete rock structures placed at the top of a beach or the foot of a cliff to break up the waves energy
What are the advantages and disadvantages of recertments?
Advantages
Relatively cheap
Disadvantages
High maintenance levels
Unattractive
What’s offshore break water?
A partially submerged rock barrier designed to break up the ways before they reach the coast.
What are the advantages and disadvantages of offshore breakwater?
Advantages
Effective
Disadvantages
Potential hazard for navigation
Unattractive
