G3: Distinctive Landscapes Flashcards
What are the 5 ways landscapes can be defined?
○ Physical features ○ Water features ○ Biological features ○ Transitory features ● Light, Seasons, weather etc. ○ Human features
How are Upland and Lowland areas in the UK distributed?
○ Upland ● North & West of the UK ● Scotland, Wales & North England ○ Lowland ● South & East of the UK
What are some examples of Upland and lowland areas?
● Upland - The Grampians & The Pennines
● Lowland - South Downs & The Cotswolds
What is the quaternary period?
A period of time we are on that has lasted 2.5 million years
● It consists of glacial and interglacial periods
↳ During glacial periods, glaciers creep from the poles to cover the land
↳ During interglacial periods, these poles recede
Where has there previously been glaciers in the UK?
In the North & West, in a similar distribution to the UK’s upland areas
● This is because glaciers are responsible for forming some features via erosion
What are the impacts of Glaciation in Periglacial areas?
○ Formation of valleys
● Permafrost causes the ground to become impermeable
● Rivers form more easily and erode land away, forming valleys
● The climate enters an interglacial era, leaving a dry valley when the river water seeps into the ground
What is a geomorphic process?
A process that changes the earth. This can include…
● Weathering
● Erosion
What is the UK’s geology distribution?
○ In the North…
● There is primarily impermeable igneous rock, such as granite & Basalt
↳ This rock is older, harder and jagged
↳ This means erosion is slow and rivers and lakes form
○ In the South…
● There is primarily permeable sedimentary rock, such as chalk & limestone
↳ This rock is softer, younger and smoother
↳ Erosion is quick and the rock is permeable, causing few water features to form
What is the UK’s Climate distribution?
● It is colder in the North (Altitude etc.)
● It is warmer in the South (Equator etc.)
● It is wetter in the West (Relief rainfall & prevailing ocean winds)
● It is Drier in the East (Rain shadow etc.)
What is erosion?
When rock is worn away by water, wind or ice
What are the four types of erosion?
CASH
○ Corrasion/Abrasion
● Stones slammed against cliffs by water erode rock away
○ Attrition
● Small pebbles & stones collide in water, wearing one another down
○ Solution
● Chemicals in water dissolve certain rock.
○ Hydraulic action
● Waves force and compress air into cracks, widening them
What is Weathering?
The process of rock being worn away without movement.
What are the three types of weathering?
● Biological (Plants, wildlife etc.)
● Chemical (Carbonic acid in rain [derived from CO₂ dissolving] makes it acidic, weathering away soft rock)
● Physical (Freeze-thaw weathering)
What are the processes of Freeze-Thaw Weathering?
● Water seeps into cracks of rocks
● Water freezes and expands when temperatures fall
● Ice thaws & the cycle repeats
● The rock eventually splits
What is mass movement?
Mass movement is when cliffs made of soft rock becomes unstable due to constant erosion and weathering, causing them to collapse
What are the four steps of mass movement?
● Saturation: Rock becomes heavy with absorbed water
● Undercutting: Sea & waves erode the cliff’s bottom, destabilising it
● Slumping: The cliff collapses and the rock slides down the cliffside
● Transportation: Slumped material is transported away by water
What is transportation?
Transportation is the ways that sediment can be moved by a water source, such as a river
What are the four types of Transportation?
● Solution: soluble rocks are dissolved in water and moved
● Suspension: Sediment particles (silt) are held and suspended in water and moved
● Saltation: Small rock particles bounce along the river/sea bed (gravel + sand)
● Traction: Large rocks/particles are rolled along the river/sea bed
What is deposition?
Deposition is when sediment is dropped due to a body of water losing velocity
How are headlands and bays formed?
● When there are bands of soft and hard rock at a coast, the soft rock erodes faster
● The soft rock recedes, forming a sheltered bay where deposition is encouraged, creating beaches.
● The remaining hard rock forms headlands, which are exposed to the full force of the waves and slowly erodes away
How is a Stack formed?
● Lines of soft rock in headlands erode, creating weaknesses
● Between high & low tide, waves attack these weaknesses at the cliff’s base
● This undercuts the cliff’s base, forming a wave cut notch (crack)
● This notch is enlarged by hydraulic action over time to form a cave
● Waves bend around the headland and hit the other side, forming an opposite cave. Both these erode back and meet, forming an Arch.
● Weathering and erosion cause the roof to collapse under gravity, creating a stack.
What is longshore drift?
Longshore drift is when a prevailing wind causes waves to hit the beach at an angle, transporting sediment along the beach.
How is a spit formed?
● Longshore drift transports sediment until it reaches a change in The coast (i.e. at the mouth of a river)
● Where the colliding forces of the river and waves are equal, sediment is deposited and a spit forms
● Wind & wave changes causes this spit to curve
● This spit blocks the waves energy and allows a marsh to grow behind it
What are the commonly seen features of each river segment?
○ Upper Course ● Waterfalls/Gorges ● V-Shaped Valleys ○ Middle Course ● Meanders ● Ox-Bow Lakes ○ Lower Course ● Floodplains ● Levees
What are the characteristics of a river’s upper course?
● Narrow ● Steep ● Shallow ● Slow-moving ● High friction ● low discharge ● Erodes Vertically
What are the characteristics of a river’s Lower course?
● Wide ● Gentle ● Shallow ● Fast-moving ● Low friction ● High discharge ● Erodes laterally
How are V-Shaped Valleys formed?
● Water erodes rock vertically (due to gradient)
● Weathering weakens channel walls
● Mass movement forces material into the channel, which is transported away
● A V-shaped valley is left
How are waterfalls formed?
● A layer of Hard rock lies over soft rock.
● The soft rock erodes away faster
● H.A. and abrasion undercut the back wall, forming an overhanging ledge of hard rock
● Falling upstream material drills downwards into the soft rock and forms a plunge pool
● The unsupported ledge falls & is eroded away, causing the waterfall to retreat
● Constant retreat leaves a gorge behind
CASE STUDY: High force, A waterfall in the River Tees
● Is composed of the hard rock Whinstone (Or dolerite) and the soft rock Limestone
● Marks the rivers drop from 301+ metres of height range to the 61-300 metres of height range
What is the difference between the inside and outside of a meander?
○ Inside ● Water flows slowly ● There is more friction ● Water loses its energy & deposits sediment ● A gentle slip-off slope forms ○ Outside ● Water flows quickly ● There is less friction ● More erosion (abrasion) occurs ● A steep river cliff forms ○ This means meanders migrate and expand in the direction of the river cliff over time.
How are Ox-Bow lakes formed?
● Because water flows in a Corkscrew fashion, the river bends
● Increased erosion on the outside of bends forms a meander
● The meander expands, and erosion at the neck of the meander slowly narrows it
● During flooding, the river will break through the meander’s neck, forming a straight channel
● Deposition will occur at the meander bends, eventually sealing the meander off and forming an Ox-Bow lake
How are floodplains & Levees formed?
● Meanders in the lower course erode laterally at the river cliff, causing them to migrate.
● This migration widens the river valley
● When the valley floods, sediment in the river is deposited at its banks as the river loses energy due to friction
● As the area repeatedly floods, piles of debris and material with steep side form on the edge of the river, called levees. Furthermore, fine alluvium is deposited on the valley floor to build up and create floodplains
What is the difference between Soft and Hard engineering?
Soft engineering is a way of maintaining a coastline by working with natural processes, whereas hard engineering works against them
What are the four Shoreline management plans
● Hold The Line: The coastline is kept constant
● Advance The Line: The coastline is expanded
● Managed Retreat: The coastline is allowed to retreat at a controlled rate
● No Active Intervention: Take no action
CASE STUDY: Overstrand
What landforms exist at Overstrand?
● Sand & Shingle beaches, formed by the eroding of glacial Till
● Blakeney Spit & Marshes, formed by longshore drift
● Steep cliffs, formed by Mass movement
CASE STUDY: Overstrand
How are climate and Geology affecting the different Geomorphic processes at Overstrand?
○ Climate Change
● Warmer oceans mean stronger storms and rapid erosion
● Coastlines withdraw, beaches starve and cliffs slump
↳ 6m of Blakeney spit was lost in a 2013 storm surge
↳ This has and will lead to the damage of property, such as the Sea marge hotel, which will be lost by 2055
○ Geology
● Area primarily composed of soft rock deposits, underlined by chalk & formatted of Glacial Till/Boulder Clay
↳ Means erosion is rapid & deposition is high
CASE STUDY: Overstrand
How effective is the management of Overstrand?
● Management is Hold the line in many areas
↳ In areas of managed retreat, coastal erosion is 1m per year
● Overstrand implements…
↳ 9 Groynes
↳ 900m of Sea wall
↳ Gabions
↳ Revetments
● Current coastal erosion in hold the line areas is 0m per year
● Last building lost was in the 1940s
● In the future, there will be a shift from hold the line to Managed retreat
↳ Under this, 60 buildings, including the Sea marge hotel, will have been lost by 2105
CASE STUDY: Overstrand
What are the advantages and disadvantages of Management methods at Overstrand?
○ Sea wall ● Reflect wave energy, long lifespan ● Expensive, require maintenance, unattractive ○ Groynes ● Retain beach access ● unattractive, can become starved of sediment ○ Gabions ● Cheap, efficient ● Unattractive, short lifespan
CASE STUDY: 2014 River Thames flood
Case-specific information
● Source is in the cotswold hills, 100m above sea level
● No upper course features
● Primarily runs over oxford clay, an impermeable rock
CASE STUDY: 2014 River Thames flood
What were some causes of the flooding?
● There was twice as much rain as expected for 3 months due to storms [CLIMATE]
↳ The ground was saturated, reducing infiltration
↳ Water levels in the Thames were high
● Urbanisation reduced infiltration
● Deforestation reduced water interception
● Ground is impermeable clay [GEOLOGY]
● The creation of the Jubilee river increased water velocity & quantity downstream in Wraysbury & Staines
CASE STUDY: 2014 River Thames flood
What were some impacts of the flood?
● Thousands evacuated
● £500 million in repairs required
● 5,000 homes & businesses flooded in Wraysbury & Staines
CASE STUDY: 2014 River Thames flood
What were some ways the flood was managed?
● Volunteers & Boat owners assisted in evacuation
● Specialist equipment for damage prevention was lent out by organisations for free
● The Thames Barrier, 520 metres in width, was closed off, preventing water from the sea’s high tide from contributing to the flooding
● In the future, housing built in flood-prone areas will…
↳ Have Water-filled green corridors as a feature
↳ be built on raised land
↳ Have vegetation to reduce water infiltration
↳ Have relief that naturally directs water into creeks
FIELD WORK TECHNIQUES: Rivers
Measuring a River’s width
● Impale two stakes into the ground on each bank and stretch a tape measure between them
↳ Stakes must be vertically straight
↳ Tape must be taught
↳ To avoid slant, both tape fixings must be on the same horizontal level
FIELD WORK TECHNIQUES: Rivers
Measuring a River’s Depth
● Take measurements using a metre stick at set intervals, either every metre or every eleventh of the river’s total width
↳ Have the metre stick vertically straight
↳ Have the metre stick parallel to the water flow
↳ Avoid large rocks & debris (set intervals highlights anomalies)
FIELD WORK TECHNIQUES: Rivers
Measuring a River’s gradient
● Place two equivalent poles 10m apart down a river.
● Use a clinometer at the further down pole and point it at a marking on the further up pole. Measure the angle of the gradient
↳ Avoid large drops in the river bed
↳ Poles must be the same length
FIELD WORK TECHNIQUES: Rivers
Measuring a River’s flow velocity
● Method One
↳ Use a flowmeter to take measurements at a 1/4, 1/2 & 3/4 ways across the river’s width
↳ Take 6 measurements at each, holding for 10 seconds each time
↳ Hold the flowmeter stationary to get water velocity alone
↳ Do not make contact with the floor
● Method Two
↳ Place a bright & visible float in the water & measure the time taken for it to flow ten metres downstream
FIELD WORK TECHNIQUES: Rivers
Calculating a River’s Discharge
River Discharge = River width x River depth x River Velocity
