Topic 4: UK's Evolving Physical Landscape Flashcards
How have tectonic processes shaped the UK’s physical landscape?
- Convection currents have caused uplift of some land, pushing it upwards and further out to sea
- Slowly moved to its current position from Antartica 500 millions years ago
- Between collisions, huge volcanoes occurred erupting masses of lava and forming mountains
How has glaciation shaped the UK’s physical landscape?
- As the Pennines were uplifted, rivers like the Wharfe eroded into them, creating V-shaped valleys.
- But the most recent Ice Age, over 10 000 years ago, brought huge glaciers to the Pennines. They had two effects:
• altering river valleys, making them deeper and widening them into U-shaped troughs using corrosion, abrasion, freze thaw
• as they melted, the glaciers left features like Malham Cove
How has geology shaped the UK’s physical landscape?
- As tropical dosn amd coral died, skeletons fell to the sea floor, forming horizontal layers (stratas)
- As skeletons fell, they crushed those beneath them, eventually squeezing out water and compacting them into rock
- Other rock strata deposited on top of limestone- resists erosion so it forms high peaks and protects weaker sands
- Calcium Carbonate crystallises around the fragments, cementing together
What is igneous rock?
Magma cools amd hardens. Rock form crystals as it cools down. Usually hard
What is sedimentary rock?
Layers of sediment are compacted together until they become solid rock:
Limestone and chalk form from tiny shells and skeletons of sea creatures. Limestone is hard, chalk is softer rock
What is metamorphic rock?
Sedimentary rocks that were heated and compressed during igneous activity. Heating and compression harden them and make them resistant - shale becomes slate and limestone becomes marble.
What are the locations of upland in Uk?
North West- Peak District, Lake district
What are the locations of lowland
South East/ Central UK- North and South Downs
What rock types are in upland?
Resistant igneous and metamorphic- Carboniferous limestone, granite
What rock types are in lowland?
Sedimentary- Limestone, chalk, clay
What are features of the upland?
Valleys, glacial deposits, volcanoes
What are features of the lowland?
Wide valleys, forest historically, farmland
What is an example of sedimentary rock and its properties?
Limestone:
Coral/ sediment and pressure over time. Made up of layers
Permeable, underground rivers
Generally resistant
What is an example of igneous rock and its properties?
Granite:
Magma cools deep underground
Crystals of quartz
Very resistant
What is an example of metamorphic rock and its properties?
Slates:
Heated mud or shales
Very resistant
How does seasonality impact coastal erosion?
Through changing seasons, storm frequency may vary, often highest in winter. Increases in storm frequency result in the erosion and saturation of cliffs through increasing winds and rainfall. Temperature also varies with seasons. Differences in temperature have an impact on processes along the coast (eg: Increasing rate of salt weathering as water evaporates quickly
How does storm frequency impact coastal erosion?
Storms are very frequent in many parts of the Uk, especially in winter. Stronger winds create high energy, destructive waves which increase erosion pf the cliffs. Intense rainfall cause cliffs to become saturated- thus makes mass movement more likely
How does prevailing wind and fetch impact coastal erosion?
The prevailing winds in the UK are mostly warm south Westerlies which bring storms from the Atlantic Ocean. The Uk’s South is exposed to these winds and storms, further resulting in the erosion of coasts
How does mass movement impact coastal erosion?
Mass movement is the shifting of rocks and loose material down a slope, e.g. a cliff. It happens when the force of gravity acting on a slope is greater than the force supporting it. Mass movements cause coasts to retreat rapidly. They’re more likely to happen when the material is saturated — it acts as a lubricant and makes the material heavier and unstable. In rotational slumping, the material shifts with a rotation as material closer to the surface is more stable; less of it collapses. Layers of impermeable rock means it can slump. Rock slides occur as it slides quickly along a bedding plane
How does weathering impact coastal erosion?
Weathering is the breakdown of rock. This may occur through mechanical weathering (seawater gets into cracks, evaporates, salt crystals form and expand, widens cracks causing it to break up), chemical weathering (Water have dissolved CO2, making them weak carbonic acids, reacts with rock containing calcium carbonate so rocks are dissolved), biological weathering- living things (plant roots break down rocks by growing into cracks and pushing apart)
What is abrasion?
eroded particles in the water scrape and rub against rock, removing small pieces
What is hydraulic action?
waves crash against rock and compress the air in the cracks. This puts pressure on the rock. Repeated compression widens the cracks and makes bits of rock break off.
What is attrition?
eroded particles in the water smash into each other and break into smaller fragments. Their edges also get rounded off as they rub together.
What are the characteristics of destructive waves?
- Destructive waves are high, steep, and have a high frequency
- Their backwash (the movement of the water back down the beach) is more powerful than their swash (the movement of the water up the beach). This means material is removed from the coast.
- The backwash flows under the next incoming wave, forming a rip current. These can be strong and drag swimmers out to sea.
- Storms increase the erosional power of destructive waves, which can lead to increased rates of coastal retreat.
What are the characteristics of constructive waves?
- Constructive waves are low, long, and have a low frequency
- The swash is powerful and it carries material up the coast, meaning they deposit material along the coast
- The backwash is weaker and it doesn’t take a lot of material back down the coast.
What are joints?
Small, usually vertical cracks
What are faults?
Larger cracks caused by past tectonic movements
How do headlands and bays form?
- Headlands and bays form where there are alternating bands of resistant and less resistant rock along a coast.
- The less resistant rock (e.g. clay) is eroded guickly and this forms a bay — bays have a gentle slope.
- The resistant rock (e.g. chalk) is eroded more slowly and it’s left jutting out, forming a headland — headlands have steep sides.
How does an arch form?
Arch:
* Large crack, opened up by hydraulic action
* Cave becomes larger through further erosion
* Cave breaks through the headland forming a natural arch
How does a stack form?
Stack:
* The arch erodes and collapses,
* This leaves a tall rock stack- an isolated rock that’s separate from the headland
How does a stump form?
Stump:
The stack is eroded, forming a stump
How do wave cut notches and platforms form?
- Wave power is concentrated at the cliff base where abrasion forms a wave-cut notch.
- As the notch grows, a cliff overhang develops.
- The overhang becomes unstable and eventually collapses, forming a pile of rock debris. The debris protects the cliff base from further erosion.
- Over time, the rock debris is eroded by attrition, exposing the cliff to erosion again.
- Over thousands of years, a succession of wave-cut notches form, and the cliff collapses again and again, retreating inland.
- A level area of smooth rock is left where the cliff line once was, stretching out to sea, called a wave-cut platform.
What is deposition?
Deposition is when material being carried by the seawater is dropped on the coast. It occurs when water carrying sediment slows down so that it isn’t moving fast enough to carry so much sediment
How does longshore drift move material?
- Waves follow the direction of the prevailing wind.
- They usually hit the coast at an oblique angle (any angle that isn’t a right angle)
- The swash carries material up the beach, in the same direction as the waves.
- The backwash then carries material down the beach at right angles, back towards the sea.
- Over time, material zigzags along the coast.
How does a split form?
- Spits form at sharp bends in the coastline, e.g. at a river mouth.
- Longshore drift transports sand and shingle Material past the bend and deposits it in the sea.
- Strong winds and waves can curve the end of the spit (forming a recurved end).
- The sheltered area behind the spit is protected from waves — lots of material accumulates in this area, which means plants can grow there.
- Over time, the sheltered area can become a mud flat or a salt marsh.
How does a split turn into a bar?
- A bar is formed when a spit joins two headlands together.
- The bar cuts off the bay between the headlands from the sea.
- This means a lagoon can form behind the bar.
What is solution?
Soluble materials dissolve in the water and are carried along
What is suspension?
Small particles like salt and clay are carried along by the water
What is saltation?
Pebble-sized particles are bounced along the river bed by the force of the water
What is traction?
Large particles like boulders are pushed along the river bed by the force of the water
What os the rock alignment of disconcodent
alternating bands of hard and soft rock that are at right angles to the coast
What is the rock alignment for concordant?
the alternating bands of hard and soft rock (strata) are parallel to the coast
What are features caused by discordant rock structure?
Long headlands, bays
harder sandstones as headlands.
Softer limestone
What are features caused by concordant rock structure?
Coves, steep cliffs, a gap through the limestone, exposing less resistant sands and clays behind, Stair Hole
What are The downs and the Weald?
The Downs and the Weald are lowland landscapes. They are chalk escarpments that lie either side of a large, flat area of clay. The valley is flat (with some small hills). Glacial melt water eroded large amounts of sedimentary rock leaving this distinctive lowland landscape in South East England.
What is biological weathering?
Roots burrow into the rock, weakening the structure of the rock until it breaks away. Plant roots can get into small cracks in the rock. As the roots grow, the cracks become larger. This causes small pieces of rock to break away.
What is chemical weathering?
When the climate is warm and wet, carbon dioxide can dissolve in rain to create a ‘carbonic acid’. The carbonic acid in rainfall hits rocks and dissolves the parts of the rock made of calcium carbonate. This also breaks down rock.
What is mechanical weathering?
Mechanical weathering is also called physical weathering and it is a process that causes rocks to crumble. It is the breaking down of rocks where they are located, caused by rainwater, temperature extremes (eg: freeze thaw, saturation or salinization)
How are dry valleys and underground rivers formed?
During glacial periods (when the climate was colder) the gaps in the chalk froze making it
impermeable. When seasonal snow melt occurred, it couldn’t infiltrate into the chalk and
instead ran over the top and eroded the valleys. Now (it is warmer and the ground has melted)
the water runs underground through the chalk and the rivers can’t be seen.
What is soil creep?
Soils such as sandstone and clay can absorb large amounts of moisture and become saturated – they can move down the slope
How do post-glacial processes alter the landscape?
melting ice at the end of glacial periods made rivers much larger than normal with more power to erode the landscape. The ice also left distinctive landforms when it melted, e.g. hanging valleys (little valleys that are left at a higher level than the main valley).
How has sheep farming altered the landscape of the uplands- Lake District?
- the stone walls to keep them penned in which act as linear lines on the landscape
- As a source of income from sheep farming and grazing.
- As such the sheep have grazed all the vegetation and prevent shrubs and trees from growing. As a result, the Lake District will never be forested (as it once was) due to the presence of sheep and the tradition of sheep farming
What tectonic processes have affected the Lake District (Upland)
Large volcanoes erupted in Lake District caused mountain building and the formation of high altitude areas of the upland.
What is the shape of the landscape and formation of the uplands?
- you shake valleys due to erosion from glaciers, forming steep landscape
- High peaks due to tectonic activity
- Rocky elements of mountains due to weathering processes such as freeze Thor, causing instability of rocks on mountains
What is the shape of landscape and formation of the Lowland (Weald)
- V shape valleys
- Rolling/undulating hills
- More vegetation
- Shallow in height compared to Upland
What weathering processes occur in the uplands?
- free store weathering caused the instability of rocks on mountain sides
- Water gets into cracks, freezes and expands, eventually causing the erosion of rocks
What weathering process occur in the Lowland?
- Biological weathering-rocks are broken down by borrowing roots and plants as well as animals
- Chemical: rocks are broken down and eroded by acidic rain as they reach with materials within the rock dissolving the
What slope processes occur in the Lake District (Upland)?
- Screen fragments are unstable and move easily during Rockfall
- Landslides are common due to the saturation of steep land and the additional weight of rain to weather processes and due to increased precipitation
What slope processes occur in Weald (lowland)?
Soil creep-soil is such as sandstone can absorb large amounts of moisture, becoming saturated after increased precipitation. Soil tends to move down slope, forming wave like pattern/structure.
What post glacier river processes occur in the lake district?
Now the rivers in the Upland areas are fed by rainwater so the rivers are very small relative to their valleys. We call these misfit streams.
What post glacier river processes occur in the lowlands?
When rivers flood, the overflowing water carry sediment and it floods onto the valley floor forming a floodplain. This area of land is very fertile.
What is the difference in settlements between Upland and lowland areas?
Upland: farms are dispersed and isolated
Lowland: villages/town surrounding farmland
What is the difference in field boundaries between Upland and lowland areas?
Upland: stone walls-structured through shape of the land
Lowland: hedges and trees-parallel, structured
What is the difference in farming between Upland and lowland areas?
Upland: Livestock and sheep farming
Lowland: Mostly crops, arable farming
What is the difference in economic activity between Upland and lowland areas?
Uplands: Primary sector jobs- mill farming, agriculture
Lowland: Tertiary sector jobs- increased economic activity
How has industry impacted coastal landscapes?
Easington Gas Works (which processes 25% of UK’s gas) increases weight on the cliff which adds to rotational slumping mass movement. Pollution of the water, air and noise is a big problem and threatens wildlife in the surrounding area. Sand was dredged from the beach and under the sea to build up the height of gas works. This has had a consequence of increasing the height of waves and making them more destructive.
How has agriculture impacted coastal landscapes?
Tunstall farm is a farm on the edge!! A decision has been made to NOT protect the farm because it’s poor quality and low value. As a result, it is eroding 2m a year. The eroded material then is transported along the coast and deposited which is adding to beaches further down the coast. When the farmer ploughs the farm it exposes the soil and rock to rain, weathering and mass movement.
How has coastal management impacted coastal landscapes?
Coastal management and protection often protects an individual area from erosional processes on the coast. However, coastal management such as groynes may result on the deprivation of sediment in surrounding areas, reducing natural protection and thus increasing erosional processes in other areas,
How has the development of towns and cities impacted coastal landscapes?
By building a harbour (and extracting/dredging sediment) negatively affected the stability of cliffs which have collapsed more. The boats and runoff from the land has also polluted the water quality more. Furthermore, infrastructure may increase the weight exerted on land, causing it to collapse under its own weight. The foundation of buildings may also interrupt the natural structure of sediment beneath, resulting in further instability.
in this area.
How has sea level risen?
- Increased greenhouse gasses through various factors such as increased ownership of cars, increased demand of industry due to rising population and the increased energy consumption resulting in the burning of fossil fuels for energy have resulted in global warming, trapping reflected radiation from the sun within the earth’s atmosphere
- Melting glaciers and ice sheets which initially lay of land have increase the total volume of sea water
- Thermal expansion due to rising temperatures has further caused sea level rise
How may changes in global temperaturs threaten those in coastal areas?
- Rising sea levels in itself may result in flooding of coastal areas, resulting in the displacement of locals
- Flooding caused by rising sea levels may result in the saturation of sediment, decreasing stability and causing the retreat of coastal areas
- Increased temperatures results in increased rate of evaporation of sea water, causing salt weathering
- Increased temperatures may also result in increased frequency of storms, resulting in frequent destructive waves on the coast, causing coastal areas to retreat through increased erosion (hydraulic action)
How do groynes reduce erosions?
Groynes are used to prevent longshore drift, transporting sediment along the coast and encourage the deposition of sediment onto beaches. As the beach gets bigger it will be able to absorb wave energy and therefore protect the coast from erosion
What are the benefits of groynes?
- cheapest form of hard engineering (about £100,000 per km)
- Creates larger beaches for tourists
- Prevents the coastal erosion of cliffs, protecting both land and residents above
What are problems of groynes?
- Visual pollution and prevent beach walks
- Trap sediment and indirectly starve beaches along the coast of sediment, making erosion worse further down the coast, costing more
How do sea walls reduce erosion?
They deflect wave energy back out to the coast, protecting the coast/ cliffs behind from erosion. They are curved so the energy is focused out to sea, away from the cliff.
What are the benefits of sea walls?
- Provide a long term protection to the coast
- Provide a promenade walk way on the top for tourists which is good for business.
What are the problems and costs of sea walls?
- Many say that they are ugly and make it hard for tourists to get down onto the beach
- Extremely expensive approx £5 million per km
How does beach nourishment reduce erosion?
Adding sediment to a beach builds up the beach height The beach absorbs wave energy and prevents waves breaking at the base of the cliff.
What are the benefits of beach nourishment?
- Looks natural and attracts tourists to beach by a bigger beach
- Relatively cheap
- Doesn’t affect erosion down the coast
What are the problems and costs of beach nourishment?
- £ ½ million to 1 million per km
- Replacement of sediment is often needed
- Winter storms transport material away
How does slope stabilisation reduce erosion?
Vegetation is planted by laying geo- meshes and planting grasses and shrubs – the roots can stabilise soil. Drainage pipes are placed which reduces water pressure and prevents saturation. Together, these reduce mass movement slumping
What are the benefits of slope stabilisation?
- They don’t interfere with transportation and it doesn’t increase erosion down the coast
- Together, these reduce mass movement
- Keeps cliff in place and is safer for beach users
What are the problems and costs of slope stabilisation?
- Difficult to install and beach may be closed for long time
- Up to £1million for full slope stabalisation
What are two examples of hard coastal management?
- Groynes
- Sea walls
What are two examples of soft coastal management?
- Beach nourishment
- Slope stabilisation
What is the meaning of ‘holding the line’
The use sea defences to stop erosion and so the coast stays where it is - expensive
What is the meaning of ‘advancing the line’?
By building new defences on the seaward side of the original defences - very expensive
What is strategic retreat/ realignment?
Gradually let low value areas of the shoreline to erode backwards to help protect high value areas. Compensation is given.
