UK's Physical Landscape Flashcards
What are igneous rocks?
Rocks created by immense heat and magma that cools once leaving a volcano- most resistant form of rock (granite and basalt)
What are metamorphic rocks?
Rocks transformed from either sedimentary or igneous rocks through immense heat and pressure. (Slate and marble)
What are sedimentary rocks?
Rocks that’s are created by layers of sediment compacting together over 1000s of years (clay, sandstone, limestone)
What is freeze thaw weathering (mechanical)?
This involves water continually seeping into cracks, freezing as it gets colder, expanding and eventually breaking apart. This occurs when rocks are porous or permeable.
What is biological weathering?
When plant roots can get into small cracks in rocks. As these roots grow the cracks get larger and the rock breaks away
What is tectonic uplift?
When the earth’s crust drifts and lifts due to convection currents. This forces land upwards to form ridges and fault scarps (e.g. gigglewick scar)
What is scarp and vale topography
Caused by rain dislodging soil particles. More resistant rocks form steep escarpments which stick out and softer clays are eroded more easily so form vales between two scarps
How has glaciation formed U shaped valleys?
Glaciers form in v shaped valleys and move slowly down the valley they erode through plucking and abrasion - making it deeper and wider. Glaciers will then retreat widening the valley even more
How have people changed the landscape through agriculture, forestry and settlements?
Agriculture-different areas are suited to certain types of farming (sheeps in upland areas and arable farming in lowland areas)
Forestry-planting, managing and caring for forests for different purposes such as conservation, deforestation and industrialisation.
Settlements -often concentrated in areas where landscapes are advantageous (harbours, towns)
What is the geology of the UKs north and south?
Upland landscapes = u-shaped valleys, mountains streams
Lowland landscapes = rivers, flatter land
What is a Concordant coastline?
When rock is parallel to to coastlines and often made up of the same rock
What are discordant coastlines?
When rocks are perpendicular to the coastline and rock types often alternate in layers (formations are usually headlands and bays)
How are headlands and bays formed at discontent coastlines?
- less resistant rock is eroded away quicker forming bays that grow in size as this rock is continually eroded backwards
- more resistant rock is harder and slower to erode so forms headlands that stick out.
- wave action is now concentrated on the headlands so they often form stacks/stumps and deposition of sediment to form beaches
How are coves and wave cut platforms formed at Concordant coastlines?
- rock is parallel so is continually eroded backwards in all directions
- wave cut notches are also created as constant wave action is concentrated towards the bottom of the cliff causing undercutting. Above rock then collapses and the cliff front retreats inwards leaving a wave cut platform.
How are stacks and stumps created?
- faults and joints appear in headlands but high energy destructive wave energy is now concentrated eroding the headland more
- hydronic action and abrasion widens the faults even more and cracks turn to caves to then be eroded through into arches
- they then collapse to form stacks and stumps
What are the 4 types of erosion?
Abrasion=bits of rock and sand in waves grinding down cliffs
Attrition = waves smash rocks onto the shore and they break it become smaller
Solution= acids contained in sea water will dissolve rock like chalk
Hydrolic action = air becomes trapped in faults and joints and when waves hit the air is compressed weakening the cliff
How are waves created?
- wind blows over the surface of the sea creating friction, this provides a swell in the water
- energy in the wind causes water particles to rotate in the swell moving the wave forward
- wave breaks as top moves faster than the base due to seabed friction
What influences how strong waves are?
how long the wind has been blowing for, strength of the wind, the fetch of the wave (how far has it travelled)
What are constructive waves?
Less powerful waves that have a short fetch so have less energy. Their swash is stronger than their backwash
What are destructive waves?
Strong waves due to long fetches which build up lots of energy. They have a stronger backwash than swash and are plunging breakers
What is swash and backwash?
Swash-water is washed up the beach as waves break at 45°
Backwash- water runs back down the beach after the wave has broken (90°)
What are sub Ariel processes?
Those that occur on the cliff face as oppose to the cliff foot and are influenced by weather and climate
E.g. weathering and mass movement
What is cliff slumping?
- precipitation infiltrates and percolates through upper cliff soft rock causing it to become saturated and unstable
- it then reaches impermeable hard rock so water builds up
- at a slip plane, the cliff then slumps and is debris is carried away by wave actions
What is Chemical weathering?
When rain or substances are slightly acidic so rock is eroded. For example this causes limestone to dissolve
What is longshore drift?
- The prevailing wind comes from a south western direction so pushes sediment up the beach at a 45° angle (swash)
- gravity then pulls sediment down the back at a 90° angle
- this transports sediment across the beach from west to east
What are the 4 transportation processes?
Saltation-when a rock knock into eachother causing it to bounce
Suspension -fine sediment is suspended in water
Traction - when a rock rolls due to the force of the water, making it smaller through friction
Solution - dissolved load in the river
Where do sandy beaches occur and how?
Tend to form in bays as they are low energy environments as they are sheltered from high water energy. This allowed deposition by constructive waves
Where do pebbled beaches occur and how?
Tend to form in areas with eroding cliffs that are exposed to high energy wave action. Pebbles are often rounded and smoothed by wave action (these beaches are steeper than sandy ones)
How does a spit form?
Spits are fingers of sand across and estuary
- sediment is moved along the beach by LSD and when there is a change in the direction of coastline like an estuary the transported material is deposited offshore
- stretches across the estuary but is limited in size due to its velocity of currents and deep waters
- as spit grows sheltered waters appear behind the spit causing finer sediment to settle and fill in the area forming salt marshes
- spit becomes curved due to current and secondary wind direction
What might spits form?
- If spits grow a lot they may form a hook if the wind changes direction
- in slack water behind the spit more deposition takes place and may form a salt marsh and eventually new land
Why won’t a spit form a bar across an estuary?
As the rivers current stops deposition due to its velocity
How is a bar formed?
Bars form the same way as spits through LSD but form across a bay joining up two headlands and creating a lagoon behind the bar as water becomes dammed
How are tomobolos formed?
When there is a change in the shape of a headland a spit grows out from the mainland and joins to another island
How have humans impacted the coast?
- industry and infrastructure is of high value so often needs protection from erosion e.g. sea walls. Yet this prevents natural costal change
- tourism increases need for beach protection and more pollution
- dredging sediment from seabed construction
- farmland often isn’t protected as its value is too low -less biodiversity
Why are costal regions at risk?
- Thermal expansion provides more energy for sea water particles
- destructive waves are more violent - storm surges
- melting of polar ice sheets so sea levels are rising
- post glacial rebound
- land subsidence means land is sinking due to tectonic activity and the weight of infrastructure
