Topic 4 - UK's Physcial Changing Landscape Flashcards
How has past tectonic/glacial processes which has affected the upland/lowland landscape in the UK?
Upland Uk: Scottish Highland the Lake District and the Pennines in the north and north-west of the UK (rugged / steep relief / weathered rocks)
Active volcanoes : 520 million years ago erupted magma onto the UK landscape (igneous rock - granite)
Plate collisions: formed by rocks folding and uplifting as a result of plate collisions (hard metamorphic rock)
Lowland UK: South and East of the UK. Cities like Norwich + East Anglia lowland area (fertile soil / relief / used for agriculture)
Plate movements: The UK was in the tropics 345 million years ago sea levels were also higher, and so carboniferous limestone ended up forming in the warm and shallow seas.
Distrubution of main rocks type in UK
Igneous rocks- formed when molten rock from the mantle cools and hardens (granite) - formed in the North of the UK
Sedimentary rocks - compacted sediment until the rock become solid :
- Carboniferous limestone and chalk are formd from shell/skeletons of dead sea creatures.
- Clays and shakes are made from mud and clay minerals (soft)
Appears in the SE of UK
Metamorphic rocks- other rocks are changed by heat and pressure and the new rocks are more compacted (shale/slate/schist) - North UK
Examples of physical processes:
Explain how distinctive upland and lowland landscapes are created by past processes
Mechanical weathering : sea water gets into cracks- evaporation occurs crystal form and expand- rock widens
Chemical weathering: carbon dioxide reacts with rocks to form dissolve it
Biological weathering: plant roots grow within cracks pushing it apart
Erosion: ice / rivers / sea erode the landscape
Post-glacial river processes: ice melt causes river to melt (more powerful) - valleys created
Slope processes: mass movements - rockfalls,slides,slumps (force from thematerial on a cliff is greater than force supporting it)
Distinctive upland landscape:
Uk used to be covered by a massive ice sheet 2.6 million years ago (glacial period). The glaciers managed to erode the landscape, craving out U -shaped valleys. The glaciers deposited lots of material as they melted
Distinctive lowland landscapes:
When the climate was much colder the land was frozen over. Rivers flowed and create valleys. However, when the climate warmed the permeable chalk disappeared (dry valleys)
How has human activity effect the human landscape over time
Agriculture:
land cleared to create space for farming
(Arable flat land used for cops / warm, wet and open area for dairy / upands used for sheep herding)
Extensive sheep herding has also flattened the soil making it imperable for soil - surface run off is encoriaged- this result in flooding and more erosion.
Forestry:
Woodland managed (coniferous trees planted for timber whereas deciduous trees are cut to create room although are being replanted)
Settlement:
Concrete land affects drainage patterns / rivers diverted / channel created or embankments
How does the geological structure and rock types influence formation of coastal landscapes
Coastline can be concordant , alternating bands of hard and soft rock are parallel to the coast thus erosion occurs at different rates.
Coastlines can also be discordant, as the rocks are not parallel to the coast. As a result waves erode the softer rocks causing bays and headlands to form.
Addiitonally, rock typed such as resistant limestone or soft chalk/clay can affect the formation of coastal landscape alomg with pre-existing joint and faults which can create weaknesses.
How does the UK climate, waves and mass movements affect the rate of coastal retreat
Uk Climate:
Coldest during Winter and hottest during Summer
Winter Storms can create strong winds resulting in destructive waves to erode the coast. Furthermore, intense rainfall can cause cliffs to become saturated - creating mass movement
Mild temperature can increase the rate of salt weathering
Destructive waves:
High,steep and high frequency (10-14 waves per min) - their backwash is more powerful than their swash. As a result more material is removed.
Mass movement:
Waves cause the most erosion at the foot of the cliff. As a result a wave-cut notch is formed which is enlarged as erosion continues. The rock above the notch eventually becomes unstable and collapses. The material is washed away and the process is repeated causing the cliff to retreat further.
How does transportation of sediment and deposition processes influence coastal landscapes (spits and bars)
Transportation:
Longshore drift transports material through prevailing wind direction. As a result swash (low,long and low frequency waves 6-8 per min with a powerful swash) carries material up the beach and backwash takes material away to the sea. Eventually, material zigzags along the coast.
Spits and bars:
Spits- occurs at sharp bends in a coastline
Longshore drift transports sand and shingle past the bend and deposits it within the sea
Strong winds and waves curve at the end of the spit forming a recurved end
The sheltered area behind the spit is protected from waves- material is accumulated there.
Over time the area becomes a salt marsh or a mud flay.
Bars:
Formed ehen two spits joins two headlands together.
The bar cust off the bay between the headlands from the sea
As a result a lagoon is formed from behind the bar
How do human activities affect coastal landscapes
What is a direct and indirect impact
Agriculture:
Often left unprotected due to its low economic value. This had a direct effect on the coastlal landscape as the sea can erode it easily.
Furthermore, vegetation can support to bind soil and cause stable clifftops. However, clear crops through grazing can cause underlying rock to become vulnersble to weathering.
Draining marshlands can reduce the natural flood barrier that it provides making the underlying rock more susceptible to weathering processes.
Development:
Coastal area are popular thus have lots of infrastructure. Furthermore, coasts with a lot of settlements may have more coastal defences as people want to protect their homes and business (more protected against erosion).
However a change in transportation and deposition may be an indirect cause by development. This is ebcause building on coatsal lowlands may restrict the sediment supply. As a result more vulnerable to erosionsl processes.
Industry:
Coastal quarries expose vast amount of rock making them vulnerable against weathering processes. Furthermore, extraction of materials e.g gravel may increase the vulnerability of coasts to erosional processes. Lastly, building on salt marshes which are ideal for port and industry can make the coast more vulnerable to erosion as it is a natural flood barrier.
Coastal management:
Management strategies may alter movement of sediment (beach nourishment). As a result may increase erosion down the coast. Additionslly, coastal defences can prevent the landscape from changing as it reduces erosionsl processes.
Direct impact: immediate result of human activity
Indriect impact: happans as a result of direct impacts.
How does physical processes cause change of the Holderness coast
Physical factors:
Erosion causes the cliffs to collapse. About 1.8 m of land is lost to sea every year in areas such as Great Cowden, the rate of erosion has been over 10m a year.
The cliffs are mostly made up of boulder clay which is easily eroded and slumps when wet causing cliffs to collapse.
Additionally beaches along the Holderness clast are narrow, which means they don’t provide enough protection for cliffs against the sea’s erosionsl power.
Prevailing wind direction, bring waves from the NE which increase in power as it travels long distances. Additionslly, longshore drift moved South along the coast exposing new areas of cliff to erosion
Why is there increasing risk from coastal flooding and people/environment
Rising sea levels:
Threatful to low-lying coastal areas. An increase in sea levels could cause higher tides that can flood coastal area more frequently. Furthermore, higher tides can remove larger deposits of material which may lead to an increase of erosion. Lastly, rising sea levels will expose more of the coastline to erosion casuomg the beach to become narrower.
Storm frequency:
Due to changes in climate storms are more frequent. Storms increase the erosionsl power of waves. As a result sediment will become more vulnerable and erode quicker. Furthermore, high energy waves will carry sediment at greater distances starving the beach of sediment leading to it to become vulnerable to erosion. Lastly, storm surges become more frequent as sea level rise.
Risks to people:
Low lying coastal area can be permanently flooded and become unhabitable.
Coastal industries forced to shut doen after being destroyed frequently.
Risk of damage to infrastructure such as roads and railways networks (railway lines within Dawlish Devon)
Lastly, flooding and erosion can impact the tourism aspect for people, loss of livelihoods.
Threats to the environment:
Seawater has a high salt content which can kill microorganisms and reduce soil fertility (damage agricultural land)
Force of floodwater will be able to uproot trees and plants, standing water may also drown vegetation.
Conservation areas are threatened by coastal erosion e.g lagoon on the Holderness coastline
Costs and benefits of hard engineering/ soft engineering do nothing approach and sustainable approaches
Hard engineering- man made structures built to reduce flooding and erosion
Sea wall benefits:prevents erosion / acts as a barrier / reflect waves back to sea
Sea wall costs:creates a strong backwash which erodes under the wall /expensive to build and maintain
Groynes benefits create wider beaches which slow the waves. As a result this gives greater protection for flooding and erosion /cheap
Groynes costs: starve the beaches down the coast making it narrower which are vulnerable to erosion.
Soft engineering-scheme set up using knowledge of the sea and processes to reduce its impacts
Beach replenishment benefits: wider beaches created which slow waves. As a result it gives greater protection against erosion.
Beach replenishment costs: taking material from the seabed can kill microorganisms / expensive / has to be repeated
Slope stabilisation benefits: prevents mass movement by increasngnthe strength of the slope
Slope stabilisation costs: Very expensive / difficult to install
Strategic realignment benefits: Overtime the land will become a marshland which will create a new habitat. Furthermore, erosion and flooding will be reduced behind the marshland
Strategic realignment costs: People will disagree about which land is allowed to flood e.g flooding farmland can impact livelihood of farmers
Lastly another approach is to do nothing and allow the coast to naturally erode.
Sustainable approach:
Integrated Coastal Zone management is a long term , effective, and beneficisl coastal strategy to reduce erosions
How does river landscapes and characteristics differ along the upper /mid/lower
Upper course:
Steep gradient
V-shaped valley with steep sides
Narrow and shallow channel
Vertical erosion occurs the most high due to the rough angular particles scraping along the river bed
Middle course:
Medium gradient
Gently sloping valley sides
Wider and deeper channel
Lateral erosion occurs here. This widens the river valley
Lower course:
Gentle gradient
Very wide ,almost flat valley
Very wide and deep channel
Lateral erosion occurs here. This widens the river valley
Interactions of weathering/ erosional processes/ transportation/ depositional processes on river landform formations
Freeze thaw weathering breakers down rocks on the valley sides .This occurs when temperature alternates above and below 0°c . Water gets into cracks and expands when forming into ice. It then expands causing further cracks inside the rock.The ice melts and this process is repeated
Erosional processes:
Hydraulic action- force of water breaks rock particles from the river channel
Abrasion-eroded rocks scrape against the river bed and walls
Attrition- eroded rocks smash into each other breaking into smaller fragments
Solution- river water dissolved some type of rock e.g chalk and limestone
Transportation:
Traction-large pieces of sediment roll along the river bed by force of the water and erode the landscape
Saltation- pebble sized pieces of sediment roll along the river bed by force of the water and erode the landscape
Suspension- small particles are carried along by the water (silt and clay)
Solution- soluble material are dissolved in the water
Deposition:
Deposition can vary within the river path factors such as volume of water, amount of deposited sediment, shallow water and the river reaching its mouth can affect the deposition.
Influence of climate, geology and slope processes on river landscapes
Climate:
Wetter climates have a higher discharge due to more rainfall entering the river channel. As a result volume of river increased and the rate of erosion. As it is able to carry heavier load of sediment. This increases lateral and vertical erosion and transportation of sediment. Additionally, freeze thaw weathering will be more common eroding the sides of the river valley.
Geology:
rivers flowing through hard rock have a slower rate of erosion as it is more resistant whereas softer rocks are eroded more. Landscapes with more resistant rock have steeper valley sides whereas aras with softer rock have gentle sloping valley sides.
Water falls form when there is a layer of hard rock above softer rock
Interlocking spurs occur when soft rock is erode first leaving areas of resistant rock sticking out
Slope processes:
Vertical ersoion makes valley side steeper increasing movement of material down a slope
Mass movement e.g slumping can occur during cold/wet weather causing erosion to occur.
Soil creeps can occur when soil travels down a slope due to expansion (when wet) and contraction (when dried). This adds a lot of fine materisl to the river load
How can hydrographs and lag times be explained physical factors
Geology- water cannot infiltrate impermeable rocks, so there is no runoff,
Soil type- more impermeable soil can’t absorb much water which increases runoff. Shallowe soil may also become saturated more quickly than deeper soil leading to more surface runoff.
Slope- steeper the slope, the less infiltration and higher the runoff.
Drainage basin type- circular drainage basins have a shorter lag time and high discharge than narrow basins as water reaches the river channel at the same time. On the other hand , in a narrow river basin water takes a long time to get to the main channel.
