Paper 1.3 Flashcards
What is mechanical weathering?
The breakdown of rock without changing its chemical composition.
What occurs during freeze-thaw weathering?
Water enters rocks with cracks, freezes, puts pressure on the rock, and when it melts, it releases pressure, causing the rock to break up.
What is chemical weathering?
The breakdown of rock by changing its chemical composition.
What is carbonation weathering?
Occurs in warm wet conditions where carbon dioxide dissolves in rainwater to form carbonic acid, reacting with rocks containing calcium carbonate.
Define mass movement.
The shifting of rocks and loose material down a slope due to gravity.
What is sliding in the context of mass movement?
Material shifts in a straight line along a slide plane.
What is slumping?
Material rotates along a curved slip plane.
What happens during rockfalls?
Material breaks up, often along bedding planes, and falls down a slope.
How are waves created?
When winds blow over the sea, transferring energy to create waves.
What are destructive waves?
Waves that erode the coast, have a high frequency, and have stronger backwash than swash.
What are constructive waves?
Waves that deposit material, have a low frequency, and stronger swash than backwash.
What is hydraulic action?
When waves crash against rock and compress the air in the cracks, causing material to break off.
What is abrasion?
When eroded particles in the water scrape the rock and remove small pieces.
What is attrition?
When eroded particles in the water collide and break into smaller, more rounded pieces.
Define longshore drift.
Waves hit the coast at an oblique angle, causing material to zigzag along the shore.
What is traction in transportation?
Large boulders are pushed along the sea bed by the water.
What is suspension?
Small particles like clay are carried in the water.
What is saltation?
Pebble-sized particles are bounced along the sea bed by the water.
What is solution in transportation?
Soluble minerals dissolve in water and are carried along.
What occurs during deposition?
Water carrying sediment loses energy and slows down, leading to the accumulation of material.
How does coastal rock type affect erosion?
Hard rocks take longer to erode compared to soft rocks; rocks with faults erode faster.
What is a discordant coastline?
A coastline made of alternating bands of soft and hard rock at 90 degrees to the coast.
What is a concordant coastline?
A coastline where the alternating bands of soft and hard rock are parallel to the coast.
What are headlands and bays?
Landforms that form on discordant coastlines where softer rock erodes quickly to create bays.
Describe the erosion process of a headland.
Waves enlarge cracks by hydraulic action and abrasion, forming caves, arches, and eventually isolated stacks.
What are wave cut platforms?
Formed when waves erode the base of a cliff, creating a notch that leads to cliff retreat.
What is a beach?
A landform found between high and low water marks, formed by constructive waves.
What characterizes sand beaches?
They are formed by low energy waves, are flat and wide, and consist of small particles.
What characterizes shingle beaches?
Formed by high energy waves, they are steep and narrow with larger particles.
What are spits?
Landforms that form at sharp bends in the coast where sediment is deposited by longshore drift.
What are bars in coastal geography?
Formed when a spit joins two headlands together, cutting off a bay from the sea.
How are sand dunes formed?
When wind moves sand up the beach, creating embryo dunes which are stabilized by vegetation.
What is hard engineering in coastal management?
Man-made structures built to control the flow of the sea, flooding, and erosion.
What is soft engineering in coastal management?
Schemes that use natural processes and knowledge of the sea to manage erosion without man-made structures.
What is a sea wall?
A wall made from concrete that reflects waves back and prevents erosion but can create backwash.
What are gabions?
Walls of wire cages filled with rocks that absorb wave energy and are relatively cheap to build.
What is rock armour?
Boulders piled along the coast to absorb wave energy, which can be moved by strong waves.
What are groynes?
Fences built at right angles to the beach that trap material from longshore drift.
What is beach nourishment?
Adding sand and shingle from elsewhere to create wider beaches and protect against flooding.
What is dune regeneration?
Restoring or creating dunes by nourishment or planting to stabilize them.
What is managed retreat?
Allowing the sea to flood land behind removed defenses, which creates marshland.
What is a river profile?
The gradient of a river through its courses, showing changes from upper to lower course.
Describe the upper course of a river profile.
Features a steep gradient, V-shaped valley, steep sides, and a narrow, shallow channel.
Describe the middle course of a river profile.
Features a medium gradient, gently sloping valley sides, and a wider, deeper channel.
Describe the lower course of a river profile.
Features a gentle gradient, wide almost flat valley, and a wide and deep channel.
What is vertical erosion?
Erosion that deepens the valley and channel, dominant in the upper course.
What is lateral erosion?
Erosion that widens the valley and channel, dominant in the middle and lower courses.
What processes contribute to erosion?
- Hydraulic action
- Abrasion
- Attrition
- Solution
What is deposition in river systems?
Occurs when the river loses velocity and energy, leading to the dropping of eroded material.
What are the reasons for deposition?
- Volume of water decreases
- Amount of eroded material increases
- Water becomes shallower
- The river reaches its mouth
What are waterfalls?
Landforms that form when a river flows over hard rock then soft rock, leading to undercutting and plunge pools.
What are interlocking spurs?
Landforms in the upper course where rivers wind around hillsides due to vertical erosion.
What are meanders?
Large bends in the middle and lower course formed by erosion and deposition.
How is an oxbow lake formed?
Erosion causes outside bends to get closer, the neck is broken during a flood, and deposition cuts off the meander.
What is a flood plain?
A wide valley floor that sometimes floods, where material is deposited during floods.
What are levees?
Natural embankments along riverbanks created by deposited material during floods.
What are estuaries?
Found at river mouths with a wide, low floodplain where the river is tidal.
What does discharge refer to?
The volume of water flowing past a point per second, measured in cumecs.
What is a hydrograph?
A graph that shows discharge at a certain point in relation to rainfall.
What is peak discharge?
The highest discharge recorded on a hydrograph.
What is lag time?
The delay between peak rainfall and peak discharge.
What are the factors affecting flood risk?
- Heavy rainfall
- Prolonged rainfall
- Geology
- Relief
- Land use
What are dams in flood management?
Barriers across rivers forming reservoirs to control water flow and generate electricity.
What is channel straightening?
Removing meanders to allow water to leave the area more quickly, reducing flood risk upstream.
What are embankments?
Raised walls on riverbanks that increase channel capacity but can be expensive.
What are flood relief channels?
Channels that divert water around built-up areas, controlled by gates.
What are flood warnings?
Warnings shown on TV that help residents prepare for floods but do not prevent them.
What is flood plain zoning?
Restrictions on building in at-risk areas to reduce flood impact.
What is the benefit of planting trees in flood management?
Increases interception, reduces discharge and flood risk, and provides habitat.
What is river restoration?
Making the river more natural to allow flooding of the floodplain, reducing downstream flood risk.
