Topic 4: Flashcards
How are igneous rocks formed and what are there characterisitics?
Formed when molten rock from the mantle cools down and hardens, the rock forms crystals as it cools.
How is sedimentary rock formed and what are its characteristics?
Formed when layers of sediement are compacted together until they become solid rock
How is metamorphic rock formed and what are its characterisitcs?
Its formed when other forcks are changed by heat and pressure. The new rocks become harder and more compact
What are the three maun ways that past tectonic processes have shaped the Uk landscape?
Active volcanoes
- land used to be much closer to a plate boundary than it is now. Active volcanoes forced magma through the earth’s crust which cooled to form igneous rocks.
Plate Collisions
- caused rocks to fold and uplift causing mountain ranges. (Uplands)
- the intense heat, pressure caused by plate collisions formed hard metamorphic rocks
Plate movements
- britain was in the tropics and partly underwater - carboniferous limestone formed in the warm shallow seas.
- youngest rocks in Uk are the chalks and clays, formed in shallow seas and swamps, form lowland landscapes as softer.
What are the characteristics of Granite?
- very resistant and forms upland landscapes.
- has joints (cracks) which aren’t evenly spread - parts with joints wear down faster and ones with fewer wear down slower so stick out forming tors
-impermeable - creating moorlands - waterlogged land
What are the characteristics of slate and schist?
- slate forms in layers creating weak planes in rock.
- generally hard and resistant to weathering but it is easily split into thin slabs
- schist - bigger crystals, splits easily
- both form rugged landscapes
- they are impermeable
What are the characteristics of carboniferous limestone?
Rainwater eats away at limeston through carbonation weathering. Usually happens along joints.
- permeable, dry valleys, resurgent rivers (rivers opping out at surface).
What are the characteristics of chalk and clay?
- Chalk is harder than clay.
- Forms escarpments (hills) in lowland and cliffs at coast.
- permeable - water flows through it and emerges as a spring where it meets impermeable rock.
- clay is very soft and easilt eroded.
-forms wide flay valleys in lowlands. - impermeable - water flows pver the surface (streams, rivers, lakes).
Explain how back in the day the UK used to be covered in ice?
-Parts of the uk were covered in a massive ice sheet during the glacial periods.
- ice is powerful, so able to erode landscape, carving out U-shaped valleys
- glaciers deposited material as they melted.
Name the 4 physical processes changing the landscape?
Weathering - weathering breakdown of rock into smaller pieces, mechanical, chemical or biological.
Erosion - wears rock away. Ice eroded landscape, rivers do aswell.
Post-glacial river processes - melting ice at end of glacial periods made rivers much bigger than normal with more power to erode the landscape. The ice also left distinctive landforms when melted.
Slope processes- including mass movements- rock falls, slides, slumps.
Physical processes created distinctive upland landscapes…. like…..
U-SHAPED VALLEYS
- misfit rivers
-
Physical processes create distinctive lowland landscapes….like……
Flooding forming flood plain
Dry valleys- no streams, formed during colder glacial periods eith freeze thaw weathering so when glaciers melted they had much more water in them.
Humans have changed the landscape through agriculture….
- cleared forest for farming.
- hedgerows and walls have been put in for fields
- different landscapes are best for different types of farming: arable = flat land with good soil.
- dairy = warm and wet areas with large, grassy fields.
- sheep = takes place in harsh conditions in uplands. Sheep farming led to lack of trees as young trees are eaten or trampled on before they get a chance to mature
Humans have changed the landscape through forestry..
- uk was covered in deciduous trees, very little left.
- coniferous (evergreen) forest planted for timber.
- straight line planted to not natural
- in some areas, deciduous is trying to be replantes to return areas to natural stae
Humans have changed the landscape through settlement
- upland- because of hills it means that there is isolated homes. Less likely to have village and towns so you will not have a modern lifestyle because of holls.
-lowland- bridging points ovee rivers. Land was concreted over for roads, buildings. Some rivers diverted through underground channels
-some rivers striaghtened and had embankments. More urban than natural
What is mechanical weathering and explain an example of it (salt weathering)?
Mechanical weathering is the breakdown of rock without changing its chemical composition.
Salt weathering:
- seawater gets into cracks in rock
- when the water evaporates, salt crystals form. As the salt crystals form they expand, which puts pressure on the rock.
- repeated evap of saltwater and the forming of salt crystals widens the cracks and causes the rock to break up.
What is chemical weathering and give an example ( carbonation weathering):
Breakdown of rock by changing its chemical composition.
Carbonation weathering:
- seawater + rainwater have carbon dioxide dissolved in them, making them weak carbonic acids.
- carbonic acids react with rock that contains calcium carbonate.
What is biological weathering?
Breakdown of rock by living things ….. plant roots grow into cracks pushing them apart
What is mass movement?
The shifting of rocks and loose material down a slope. Causes coasts to retreat rapidly and more likely to happen if material is full of water and acts as a lubricant
What are the three main types of mass movement? Explained
Slides - material shifts in straight line
Slumps - material shifts with a rotation
Rockfalls- material breaks up and falls down slope
Describe the three processes of erosion and explain them?
Hydraulic action -
waves crash against rock and compress the air in the cracks. This puts pressure on the rock. Repeated compression widens cracks and makes bits of rock break off
Abrasion- eroded particles in the water scrape and rub against rock, removing small pieces.
Attrition - eroded particles in the water smash into each other and break into smaller peices, makes edges rounded.
What will be formed at a concordant and discordant coastline and what is the lay out of them?
Discordant:
- hard soft hard soft,,,,,, at right angles to the ocean. Bays and headlands found at these coastlines
Concordant:
- parralel to coastline , fewer erosionalcland forms here.
Hard
Soft
Hard
Soft
What do storms bring?
Destructive waves
What does mild temperature bring?
Salt weatherung uncrease due to water evaporating quicker.
Describe the attributes of a destructive and constructive wave?
Constructive wave —> big swash, small backwash, low, long frequency. Deposits material onca beach as bigger swash.
Destructive wave –> small wash, big backwash. High, steep frequency. Removes material from a beach aa bigger backwash
How are cracks, cabes, arches and stacks formed?
Waves crash into headland (mainly by hydraulic power and abrasion) causing the enlargment of CRACKS over time causing a CAVE to form.
Continued erosion deepens the cave until it breaks through the headland - forming an arch.
Erosion continues to wear away the rock supporting the ARCH, until it eventually collapses.
This forms a STACK - isolated rock that’s separate from the headland
Explain how wave-cut platforms are formed?
-Waves cause erosion at front if cliff, forming wave-cut notch, which is enlarged as erosion continues.
- rock above notch becomes unstable and eventually collapses
- collapsed material washed away and new wave-cut notch sarts
- the process repeats so cliff retreats
- wave- cut platform is the platform left behing as the cliff retreats.
Look cgp top of page 51
How are spits formed and what are they?
-Spits form at sharp bends in the coastline.
- longshore drift transports sand and shingle past bend and deposits in sea.
-strong winds and waves can curve the end of soutl
- the sheltered area behind spit is protected from waves- lots of material accumulates there, so plants can grow there.
- can become a mud flat or salt marsh.
How are bars formed and what are they?
A bar is formed whenca spit joins two headlands together.
-the bar cuts off the bay between the headlands from the sea.
- this keans a lagoon can form behind the bar
What is longshore drift and how does it transport sediment along coasts?
Waves follow the direction of the prevailing wind.
- they usually hit the coast at an angle
- the swash carries material up the beach, in the same direction as the waves.
- the backwash then carries material down the beack at rught andgles, back towards the sea. Over time, material zigzags along coast.
See top of cgp 52
What are direct effects on the coastline and indirect effects?
Direct effects: are the immediate result of human activities on coastline.
Indirect effects: happen as a result of the direct effects. Building coastal defences in one place may increase erosion further along the coast.
What are human activities that have direct and indirect effects on the coast? (Agriculture)
-Algricultural land use has low economic value meaning left unprotected.
-clearing vegetation would expose cliff and soil leVing it vulnerable to weathering because vegetation help to bind the soil and stablise cliffs
What are human activities that have direct and indirect effects on the coast? (Coastal management)
-Some managment strategies alter sediment movement, which reduces the amount of protective beach material firther along the coast increasing erosion.
- coastal defences can also reduce erosion.
- this has a direct effect on the coast because ut prevents the landscaoe from changing.
What are human activities that have direct and indirect effects on the coast? (Development)
Coastal areas are popular to live.
- areas with more settlement will mean more protection as its higher value.
- lands better protected so positive direct impact.
- indirectly effects cliffs by causing restriction of sediment to the beach.
What are human activities that have direct and indirect effects on the coast? (Industry)
-Quarries expose large areas of rock, making them more vulnerable to chemical weathering.
-Taking gravel away from beaches for extraction removes proctection for cliffs.
Explain how climate change is increasing risk of coastal flooding (rising sea levels and storm frequency)?
Rising sea levels
- threats low-lyihg coastal areas
- higher tudes may be caused which removes largee material meaning less protection.
- it exposes ,ore of the coastline to erosion as beaches will become narrower as the sea will be able to move further inland.
Storm frequency:
- climate change causes increased storm frequency
- storms increase waves erosional power, more high energy waves meaning more material moved so less protection for cliffs. And more powerful waves mean hard rock is more vulnerable
What are the threats to people and the envrionmnet of climate change (coastal flooding)
Threats to people People:
X low lying coastal areas could flood, become impossible to inhabit.
X industries may shut because of damhe to building/eauipment.
X roads and railnetworks (infastructure) damaged.
THREATS TO ENVIRONMENT
X ecosystems damaged
X floodwater uproots trees
X conservation areas damaged
How can managment strategies be sustainable?
They must manage the cost in proportion to the benefits. Is it worth doing, is it long term, how much work will be needed.
Describe the two hard engineering coastal defences and the benefits and costs of them. (Groynes..
SEA WALL - ( a wall made of hard material like concrete thst reflects waves back to sea) - prevents erosin + acts as barrier.
- it creates a strong backwash, which erodes under the wall. They are expensive to build/maintain
GROYNES - (wooden or stone fences that are built at right angles go the coast. They trap material transported by longshore drift) - creates wider beach which slow the waves. Giving greater proctection from flooding/erosion. Cheap.
- it starves beaches further down coast of sand making them narrower which dont protect cosst as well. Leading to erosion/floods.
Describe the 3 soft engineering coastal managments and the benefits and costs? Slope stabilisation……….
BEACH REPLENISHMENT ( adding sand to beach) - creates wider beach (slows waves), more protection from flooding/erosion as stuff to protect cliffs.
- takes material from seabed can kill organisms. Very expensive
STRATEGIC RELIGNMENT (removing defences and allowing the land behind it to flood) - land can become marshland - creating new habitats, flooding/ erosion are recued behind marhsland.
- people disagree over what land is allowed to flood (farmland being flooded would affect livelihood of farmers.
SLOPE STABILISATION ( reinforcing slope with concrete naiks and covering with metal netting. - -Prevents mass movement by increasing strength of slope.
- Very expensive, very difficult to install sometimes.
What is integrated coastal zone management?
Is an approach thst aims to protect the coast while taking everyone’s interests into account.
What is hard and soft engineering?
HARD engineering is man- made structures built to control the flow of the sea and reduce flooding and erosion.
SOFT engineering schemes set up using knowledge of the sea and its processes to reduce the effects of flooding and erosion.
