Physical landscapes in the UK Flashcards
Where are UK’s upland areas?
North and west, wales and Scotland, formed of hard igneous rocks that are resistant to erosion
What and where are England’s lowland areas?
South and east, made up of soft sedimentary rocks that erode more easily
Most cities are in lowland areas
What is mechanical weathering?
The breakdown of rock without changing its chemical composition.
Give an example of mechanical weathering that affects coasts
Freeze-thaw weathering:
When the temperature alternates above and below 0 degrees
Water enters rock that has cracks
When the water freezes it expands, which puts pressure on the rock
When it thaws it contracts, releasing pressure on the rocks
Doing this repeatedly widens the crack and causes the rock to break up
What is chemical weathering?
The breakdown of rocks by changing its chemical composition
Give an example of chemical weathering
Carbonation:
Rainwater has carbon dioxide In it, which makes it a weak carbonic acid
This dissolves certain rocks
What is mass movement and when does it happen?
The shifting of rocks and loose material down a slope
It happens when the force of gravity acting on a slope is greater than the force supporting it
This causes coasts to retreat massively
What are destructive waves?
Waves that are high and steep.
Their backwash is stronger than their swash do material is removed - eroding the coast
What are constructive waves?
Low and long waves
Their swash is more powerful than their backwash so material is deposited - building the beach back
What are the three processes of erosion?
Hydraulic power- waves crash against rock and compress air into the cracks. This puts pressure on it. Repeated compression cause the rock to break
Abrasion- eroded particles in the water scrape against rock, taking small pieces off
Attrition- eroded particles in the water collide, break into small pieces and become rounded
How does material move along the coast?
Waves follow the most common wind
The waves hit the beach at an angle
The swash carries material up the beach then back down at a right angle
Over time material zigzags along the coast
What are the four processes of transportation (in the water)?
Traction - large particles are pushed along the sea bed by water
Suspension - small particles like silt are carried in the water
Saltation- pebble sized particles are bounced along the sea bed by water
Solution- soluble materials dissolve in the water and are carried
When does deposition occur?
When water carrying the sediment loses energy and slows down
What is a discordant coastline?
When soft and hard rock alternate along the coastline
What is a concordant coastline?
When layers of alternating hard and soft rock go into land from a coastline
From which type of coastline are headlands and bays formed?
From discordant coastlines, the less resistant rock is eroded faster forming a gentle slope. The resistant rock erodes slower, forming steep sides to the bay
How do headlands fork caves, arches and stacks form?
The hard rock that makes up headlands has cracks
Waves enlarge the cracks in the hard rock
Enlargement causes caves to form
Erosion continues until it breaks through to the other side, forming an arch
Water erodes the support for the arch until it collapses, creating a stack
How are ‘wave-cut platforms’ formed?
Waves erode the foot of a cliff, causing a ‘wave-cut notch’
Repeated erosion causes the rock above to become unstable and eventually collapse
The collapsed material washes away and a new notch begins
After a few repeats the cliff moves back until a platform is created
How are sand beaches made?
By low energy waves and are flat and wide - sand particles are weak and small so backwash can deposit them
How are shingle beaches made?
By high energy waves and are steep and narrow - sand is washed away but larger shingle is left behind
How are spits created?
Spits form at sharp bends in the coastline e.g a river mouth
Longshore drifts take sand and shingle past the bend and into the sea
Strong winds and waves curve the end of the spit
The area behind the spit is sheltered from waves so plants grow
How do bars form?
When a spit joins two headlands together
The bay between the headlands gets cut off
This means a lagoon can form behind the bar
How do sand dunes form?
When sand deposited by longshore drift is moved up the beach by wind
Obstacles like driftwood cause wind speed to decrease so sand is deposited
Vegetation grows on the sand, catching more sand for the sand dune
How to identify if something is a coastal landform?
If there’re stacks, cliffs or wave-cut platforms on the map
Stacks look like little blobs in the sea
Cliffs are little black lines
Wave cut platforms are bumpy edges along the coast
How to identify sand or shingle beaches on a map?
Sand beaches - yellow
Shingle beaches - yellow with speckles
How to identify spits on a map?
Shown by a beach that carries out to sea but is still attached to the land by one end
Or a sharp turn
What is a case example of an arch?
The Durdle door
What is hard engineering and what are some examples?
Man-made structures built to control the flow of the sea and reduce flooding and erosion
Sea wall - a wall in the sea that reflects waves back
Gabions - a wall of wire cages filled with rocks to absorb energy
Rock armour - boulders that are piled up along the coast to absorb energy
Groynes - fences that are built at right angles to the coast to trap materials from longshore drifts
What is soft engineering and what are some examples?
Schemes set up using knowledge of the sea and it’s processes to reduce the effects of flooding and erosion
Beach re-profiling and nourishment - sand or shingle from other places that is added to the beach
Dune regeneration - planting vegetation or adding more sand to a sand dune
What are the pros and cons of sea walls?
It prevents erosion from the coast and acts as a barrier to flooding
It creates strong backwash that eroded the underside of the wall and is expensive to maintain and build
What are the pros and cons of beach re-profiling?
It creates wider beaches which slow the waves, giving greater protection from erosion and flooding
Taking material from the sea bed can kill organisms and the method has to be repeated due to backwash
How does a ‘managed retreat’ work on a coast?
Removes the defences from the water
The land will become marshland which then protects the land behind it from erosion and flooding
What are the pros and cons of a managed retreat?
It is cheap and easy strategy, that doesn’t need maintaining and the marshland can be a habitat for new organisms
However it can flood farmland and can have a negative effect on existing ecosystems
Why do the cliffs of Lyme Regis in Dorset need protecting from erosion?
Waves from the south west erode the cliffs
In May 2008, 400m of the cliff fell into the sea
Much of the town’s eastern side is built near the cliff edge and properties have been damaged from mud slides and slumps
What is the population of Lyme Regis and how many tourists a year?
Over 3,600 people and around 500,000 tourists a year
How much money was spent on tourism in Lyme Regis in 2015?
£42 million
How is Lyme Regis cliffs being protected?
Rock armour in 1995 on the eastern end
In 2007, the beaches were renourished, existing rock armour was extended and drainage systems were improved
In 2015, 390m of rock wall and rock armour was installed
What are the pros and cons of the strategies put in place at Lyme Regis?
The beaches have caused the economy a 20% increase
The rock armour absorbs most the shockwaves
People feel more safe
Greater number of tourists mean there’s more litter and pollution
The defences stop fossils from being exposed
Some residents think the defences are too expensive
What is the path of a river if it flows downhill called?
It’s course
How steep is the course of a river at its source, middle and mouth?
Source - steep
Middle - gentle slope
Mouth - almost flat
How come rivers form channels and valleys when going downhill?
They erode the ground due to the water
What does the cross profile show?
What a cross section of the river looks like
What does vertical erosion in a river do?
Deepens the river valley and channel, making it V shaped.
Dominant in the upper part of the river
High turbulence causes materials to be scraped along the bottom, causing downwards erosion
What does lateral erosion in a river do?
Widens the river valley and channel during the formation of meanders.
Is dominant in the middle and lower courses of the river
