Coastal Landscapes Flashcards
What is weathering?
Weathering is the breakdown of rocks where they are.
What is erosion?
Erosion is when rocks are broken down and carried away by something.
What is mechanical weathering?
Mechanical weathering is the breakdown of rock without changing its chemical composition.
What happens during freeze-thaw weathering?
Water enters cracks in rocks, freezes and expands, then thaws and contracts, causing the rock to break up.
What is chemical weathering?
Chemical weathering is the breakdown of rock by changing its chemical composition.
What is carbonation weathering?
Carbonation weathering occurs when rainwater, containing carbon dioxide, reacts with calcium carbonate in rocks.
What is mass movement?
Mass movement is the shifting of rocks and loose material down a slope.
What causes mass movement?
Mass movement occurs when the force of gravity exceeds the force supporting the material.
What effect does water have on mass movement?
Water acts as a lubricant and makes the material heavier, increasing the likelihood of mass movement.
What is a scarp?
A scarp is a steep ‘cut’ in the side of a slope created by material shifting.
What are destructive waves?
Destructive waves have a high frequency and are high and steep, removing material from the coast.
What are constructive waves?
Constructive waves have a low frequency and are low and long, depositing material on the coast.
What is hydraulic power in the context of erosion?
Hydraulic power occurs when waves crash against rock, compressing air in cracks and widening them.
What is abrasion in the context of erosion?
Abrasion is when eroded particles in the water scrape against rock, removing small pieces.
What is attrition in the context of erosion?
Attrition is when eroded particles collide, breaking into smaller pieces and becoming more rounded.
What is longshore drift?
Longshore drift is the transportation of material along the coast by waves hitting at an oblique angle.
What is traction in sediment transport?
Traction is when large particles like boulders are pushed along the sea bed by the force of water.
What is saltation in sediment transport?
Saltation is when pebble-sized particles are bounced along the sea bed by the force of water.
What is suspension in sediment transport?
Suspension is when small particles like silt and clay are carried along in the water.
What is solution in sediment transport?
Solution is when soluble materials like limestone dissolve in water and are carried along.
What is deposition?
Deposition occurs when water carrying sediment loses energy and slows down.
When does a coast build up?
A coast builds up when the amount of deposition is greater than the amount of erosion.
What increases the amount of material deposited on a coast?
- Lots of erosion elsewhere on the coast
- Lots of material transported into the area
What type of waves drop more material than they remove?
Constructive waves drop more material than they remove.
What are the two types of coastlines based on rock type and geological structure?
Concordant and Discordant coastlines
How do hard rocks like granite differ from softer rocks like sandstone in terms of erosion?
Hard rocks take a long time to erode, while softer rocks erode more quickly
What type of coastline consists of alternating bands of hard and soft rock at right angles to the coast?
Discordant coastline
What type of coastline has alternating bands of hard and soft rock that are parallel to the coast?
Concordant coastline
What forms along discordant coastlines due to the presence of resistant and less resistant rock?
Headlands and bays
What happens to the less resistant rock along a discordant coastline?
It erodes faster, forming a bay with a gentle slope
What geological features are formed when headlands are eroded?
Caves, arches, and stacks
What process leads to the formation of caves in headlands?
Waves crashing into headlands enlarge cracks through hydraulic power and abrasion
What is an example of an arch formed by erosion in a headland?
Durdle Door
What is formed after continued erosion of an arch causes its collapse?
A stack
What is a wave-cut notch?
A notch formed at the foot of a cliff due to wave erosion
What happens to the rock above the wave-cut notch over time?
It becomes unstable and eventually collapses
What landform is left behind after repeated collapses of a cliff?
Wave-cut platform
What type of waves are responsible for forming beaches?
Constructive waves
What characterizes sand beaches?
Created by low energy waves, flat and wide
What characterizes shingle beaches?
Created by high energy waves, steep and narrow
What is a spit?
A landform that forms at sharp bends in the coastline
What process transports sand and shingle to form a spit?
Longshore drift
What happens to the area behind a spit?
It becomes sheltered from waves, allowing material to accumulate
What is formed when a spit joins two headlands together?
A bar
What can form behind a bar?
A lagoon
How are offshore bars formed?
Waves slow down due to friction with the seabed, depositing sediment offshore
How are sand dunes formed?
Sand deposited by longshore drift is moved up the beach by the wind
What role do obstacles like driftwood play in the formation of sand dunes?
They cause wind speed to decrease, allowing sand to be deposited
What are embryo dunes?
Small dunes formed when sand is deposited and colonized by plants
What is the significance of vegetation in dune formation?
Roots stabilize the sand, encouraging more accumulation
What are dune slacks?
Small pools that form in hollows between dunes
What are some examples of erosional landforms?
- Caves
- Arches
- Stacks
- Cliffs
- Wave-cut Platforms
Erosional landforms are formed by the removal of material from the landscape due to processes like wave action and weathering.
How are cliffs represented on maps?
Cliffs (and other steep slopes) are shown as little black lines.
This representation helps in identifying steep terrain on topographic maps.
What do wave-cut platforms look like on maps?
Wave-cut platforms are shown as bumpy edges along the coast.
These features indicate areas where waves have eroded the land.
What color are beaches shown in on maps?
Beaches are shown in yellow on maps.
This color coding helps to easily identify coastal depositional features.
What is a characteristic feature of spits on maps?
Spits are shown by a beach that carries on out to sea, but is still attached to the land at one end.
Spits are formed by the deposition of sediment and often indicate changes in coastal currents.
How are sand beaches and shingle beaches represented on maps?
- Sand beaches are shown as pale yellow.
- Shingle beaches are shown as white or yellow with speckles.
The differentiation in color helps in identifying the type of beach material present.
True or False: Caves and arches can be seen on a map.
False.
Caves and arches cannot be seen on maps due to the rock above them.
What do stacks look like in the sea on maps?
Stacks look like little blobs in the sea.
Stacks are isolated columns of rock that remain after erosion has removed surrounding material.
What are coastal defences?
Structures built to control the flow of the sea and reduce flooding and erosion.
What is hard engineering in coastal defence?
Man-made structures designed to control coastal processes.
What is a sea wall?
A wall made out of a hard material like concrete that reflects waves back to sea.
What are gabions?
A wall of wire cages filled with rocks, usually built at the foot of cliffs.
What is rock armour?
Boulders that are piled up along the coast, also called rip-rap.
What are groynes?
Wooden or stone fences built at right angles to the coast that trap material transported by longshore drift.
What is beach nourishment?
Sand and shingle added to the upper part of beaches from elsewhere.
What is dune regeneration?
Creating or restoring sand dunes by nourishment or planting vegetation to stabilise the sand.
What are the benefits of hard engineering coastal defences?
- Prevents erosion of the coast
- Acts as a barrier to prevent flooding
How do gabions benefit coastal defences?
They absorb wave energy and reduce erosion. They’re cheap and easy to build.
What is a disadvantage of sea walls?
Creates a strong backwash that erodes under the wall.
What is a major cost associated with gabions?
They can corrode over time and are considered ugly.
How do groynes impact nearby beaches?
They can starve beaches further down the coast of sand, making them narrower.
What is managed retreat in coastal defence?
Removing current defences and allowing the sea to flood the land behind.
What happens over time with managed retreat?
The land becomes marshland, providing protection against flooding and erosion.
What is one advantage of managed retreat?
It is a cheap and easy strategy that doesn’t require maintenance.
What is a conflict that can arise from managed retreat?
Flooding farmland can affect the livelihood of farmers.
What example is given for managed retreat?
Alkborough Flats, Lincolnshire.
What was created at Alkborough Flats to allow water flow?
A 20-metre-wide breach in the flood wall.
What habitats are supported by the new marshland created from managed retreat?
Habitats for many bird and fish species.
True or False: Beach nourishment is a very expensive defence.
True.
Fill in the blank: Dunes create a barrier between land and sea and absorb wave energy, preventing _______.
[flooding and erosion]
