Changing UK Landscapes Flashcards
How is schist formed?
-formed at high pressure at a convergent boundary
How is slate formed?
-formed from mudstone at convergent plate boundaries
How are metamorphic rocks formed?
-formed by heat and pressure
How is sedimentary rock formed?
- formed in layers called beds
- contain fossils
How does a batholith form?
- magma cools inside the Earth’s crust
- surrounding the igneous rock (granite) is sedimentary rock (limestone)
- the sedimentary rock erodes quickly, exposing the granite
- the cracks in the batholith become larger due to freeze-thaw weathering
- forms scree
e. g. Hay Tor in Dartmoor
How are chalk hills formed?
- the area is made up of two sedimentary rocks; chalk and clay
- the harder chalk erodes much more slowly, whilst the soft clay erodes more quickly
- this leaves chalk hills and clay valleys
Impacts of agriculture on the uk landscape
- trees are removed for fields-increase in flood risk-bird numbers decrease
- chemicals used in farming such as fertiliser affect the biodiversity
- landscapes are yellow and look unnatural
- soil acidiy decreases as fields are continuously used
What is forestry
-management of wooded areas by humans
Impact of forestry on the uk landscape?
- deciduous woodland has been replaced by coniferous trees-coniferous wood looks unnatural
- this is to produce timber more quickly, leaves do not fall of so soil quality will diminish as nutrients are not transferredto the soil
- forests are maintained for tourists -litter
- trees are planted in rows to make it easier to cut down and manage
- coppicing is used to keep the tree trunks thin so they are cut down easily-makes it look unnatural
- no woods in the uk are wild
What is a spring line settlement?
spring lines form when water collects between a layer of permeable rock that rests on top of the impermeable rock forming springs
-towns and villages that settle along these water springs are called spring line settlements
What is weathering
-the breakdown of rock in situ due to weather
What is mechanical weather?
- rocks reduce in size
- no chemical change
Describe freeze-thaw weathering
- water enters crack in the rock during the day day
- at night the water freezes and expands
- repeated freezing and thawing causes the rock to break forming scree
What is chemical weathering?
-occurs when the rock breaks down
Explain carbonation/acid rain
- rainwater picks up CO2 in the air
- the rainwater becomes carbonic acid
- this reacts with rocks like limestone causing them to dissolve
What is biological weathering?
-animals and plants break down the rock
give examples of biological weathering
- animals burrow into weak rock
- plants roots grow into the rock and break it
What is mass movement?
-the downhill movement of material under the influence of gravity
Describe sliding
- water enters cracks in the rock during the day
- at night the water freezes and expands, widening the cracks
- overtime pieces of rock will break away and fall straight down the cliff base
- these pieces of rock form scree at the base of the cliff
Describe slumping
- permeable rock is located on top of impermeable rock
- the permeable rock becomes saturated
- the impermeable rock is unable to support the heavy saturated permeable rock so it collapses
- the rock collapses in a curved motion
Hydraulic action
-when the water/air is forced into cracks in the rock
Attrition
-two rocks knocks against each other reducing in size
Abrasion
-the rocks grind against each other becoming smoother
Solution
Where rock ins dissolved in water
What does deposition cause?
- obstruction
- reduction in rivers velocity
- less river water
- increase in load
What is suspension?
-when small rock fragments float in the main river flow
what is solution (transport)
-dissolved material carried by river
what is traction
-large rocks roll along the river or seabed
What is saltation
-small pebbles bounce along the river- seabed
Explain the impact that storms can have on river landforms
- storms can cause a sudden increase in river discharge and velocity
- this increases the rate of erosion and sediment transport and means that landforms will be widened and deepened by increases in hydraulic action and abrasion
- the river can flood and sediment is deposited on the floodplain
- this raises the height of the floodplain and the levees
- which are immediately parrallel to the river
What impact does hot and dry weather have on rivers
- if the weather is dry, the discharge will be low leading to less erosion/transport.
- however if it does rain, the water will be unable to infiltrate into the ground
- so will flow into the river
- may cause flooding
What impact does freezing conditions have on rivers
- these conditions will cause the ground to freeze
- so when snow begins to melt, it will be unable to infiltrate
- causing high levels of surface run-off to the river
- this could cause a flood
Interlocking spurs
- the river at its source is small and has limited energy
- it flows naturally from side to side, around ridges in the valleys sides, called spurs
- the spurs become interlocking with those on the other side of the valley
How are gorges formed?
- over a long time, the process of undercutting and collapse is repeated
- and the waterfall retreats, forming a steep-sided gorge
How are waterfalls formed?
- hard rock is located on top of soft rock in the upper course of the river
- the soft rock erodes more quickly due to hydraulic and abrasion forming a plunge pool
- the plunge pool gets deeper and deeper
- the overhang of the hard rock can no longer support itself so it collapses
- the processor repeats causing the waterfall to retreat upstream
- a gorge may form in front of the waterfall
Explain the formation of a meander:
- as a river moves downstream in the middle course, small bends form as the river avoids obstacles such as niffles (shallow sections of the river)
- overtime, the river becomes more and more bendy due to erosion and deposition forming a meander
- on the inside of the meander the river moves much slower due to high levels of friction. this leads to deposition and the formation of a point bar.
- on the outside of the meander, the river moves much faster due to low levels of friction. this leads to erosion and the formation of a river cliff.
What is an oxbow lake?
-a horseshoe shaped lake that used to be a meander
Explain the formation of an oxbow lake
- due to erosion and deposition the meander becomes more and more bendier, narrowing the neck of the meander
- after a flood, the river cuts through the neck of the meander
- the river now takes a quicker straughter route by passing the old meander
- deposition occurs sealing off the meander
- over time, the oxbow lakes begins to fill in
- vegetation begins to grow
- eventually the oxbow will disappear altogether
How does urbanisation affect rivers?
- urbanisation has caused towns to grow, meaning there are fewer permeable surfaces
- water flows into the rivers, increasing discharge
- increasing demands for housing hgas led to new houses being built on floodplains.
- this changes the natural landscape
- rivers may be channelised or made to flow underground to make room for urban development .
- if this happnens, erosion and deposition cannot take place
How does agriculture affect rivers?
- forests can be felled to make way for farmland
- trees intercept rainfall, helping to reduce surface run-off
- removing trees means water reaches rivers more quickly
- abstracting water for irrigation reduces the flow and velocity of a river
- depositon occurs rather than erosion
How do industries affect rivers?
- big users of water, reducing amount of water
- this leads to a reduction in discharge
- this means less erosion and more deposition
- industrial processes can pollute rivers if chemicals or waste are spiled or dumped into them
- this will harm animals and destroy local habitats
- this will cause the natural river landscape to change
