UK's Evolving Physical Landscapes Flashcards
1
Q
Oldest rocks
A
Igneous
2
Q
Extrusive igneous rocks
A
When magma from under the ground erupt and the lava cools to form rock.
Finely grained/ uniform/ glassy texture
3
Q
Why are extrusive igneous rocks porous
A
Gas bubbles from eruption produce holes
4
Q
Example of extrusive igneous rocks
A
Basalt
5
Q
Intrusive rocks
A
When magma cools inside the earth, later exposed by weathering/erosion.
Coarsest grained
Little alignment
6
Q
Example of intrusive rocks
A
Granite
7
Q
Sedimentary
A
Formed over millions of years.
Made when sediments are compacted.
Contain eroded rocks/fossils/ minerals.
8
Q
Example of sedimentary
A
Sandstone
Limestone
Chalk
Clay
9
Q
Metamorphic
A
Other types of rocks subjected to extreme heat/ pressure vía igneous activity
10
Q
Where is the majority of the UK’s upland areas? What type of rocks are these?
A
North and West
Metamorphic/ igneous (more resistant)
11
Q
3 ways past tectonic processes have shaped today’s landscapes
A
ACTIVE VOLCANOES (magma cooled to form igneous rocks) PLATE COLLISIONS (folded/uplifted rocks forming mountain ranges) (intense heat/pressure forms metamorphic rocks) PLATE MOVEMENTS (long time ago Britain was in tropics and so submerged) (Carboniferous limestone from warm shallow seas and chalks/clays formed in shallow seas/swamps)
12
Q
Granite characteristics and landscapes
A
V resistant and impermeable so forms uplands and moorlands.
13
Q
Moorlands
A
Large areas of waterlogged land and acidic soil w low growing vegetation.
14
Q
Carboniferous limestone characteristics and landscapes
A
Rainwater carbonation weathers it along joints to create pavement, caverns and gorges
Permeable (dry valleys/ resurgent rivers )
15
Q
Resurgent rivers
A
Rivers that pop out at the surface when limestone is on top of impermeable rock.
16
Q
Slate and schist characteristics and landscapes
A
V hard/ resistant/ layered/ big crystals/impermeable
Form rugged, upland landscapes w waterlogged/ acidic soils
17
Q
Chalk and clay characteristics and landscapes
A
Chalk = harder than clay/ permeable
Forms escarpments in uk lowlands and cliffs at coast w one side steep/ one gentle
Water flows through and emerges as spring when meets impermeable rock.
Clay=soft/unresistant/impermeable
Forms wide and flat valleys, streams, rivers and lakes.
18
Q
What happened to uk during last glacial periods?
A
Parts of uk covered in ice sheet (Scotland wales and majority of north)
19
Q
Effects of ice on uk landscape
A
V powerful so erodes landscape via plucking/abrasion.
Deposited material as melted.
20
Q
Physical processes that alter the landscape
A
WEATHERING (mechanical, biological or chemical)
EROSION
POSTGLACIAL RIVER PROCESSES- (melting ice contributed to river’s power in eroding the landscape, leaving distinctive landforms.
SLOPE PROCESSES (including mass movement)
CLIMATE
21
Q
Soft rock characteristics
A
Easily eroded
Creates less rugged/steep cliffs
Creates bays
22
Q
Hard rock characteristics
A
Resistant to erosion
Creates high/steep/rugged cliffs
Creates wave cut platforms/ headlands w caves, arches and stacks
23
Q
Joints vs faults
A
Joint= small crack in rock
Fault = large cracks in rock
Both increase erosion rates in rock
24
Q
Factors affecting erosion
A
Geology Geological structure ‘Wave climate’ Local currents/tidal range Ground water levels
25
Tidal range
Difference between high/low tide
26
Concordant coastline
When Alternating bands of hard and soft rock parallel to the coast.
27
Discordant coastline
When alternating band of hard/soft rock are perpendicular to the coast.
28
Features found on concordant coastlines
There are fewer as their coast is eroded at an equal rate, they produce coves.
29
Discordant coastline features
Headlands and bays
30
3 ways humans have changed the landscape
Agriculture
Forestry
Settlements
31
How has agriculture changed the landscape for the good?
:) generated income supports local economy, arable farming supports rare birds, hedges/field margins=bat wildlife corridors
32
How has forestry affected the landscape for the better?
```
Creates local jobs
Provides timber
Coniferous forests prevent soil erosion and afforestation (decrease in conifers?)
Provides habitats for varying wildlife
Enhance landscape?
```
33
Effects of settlements on landscape for good
Local materials are used
| Settlements built are sheltered from naturally formed slopes
34
Weathering
Breakdown of rocks where they are
35
Erosion
When rocks are broken down and carried away by something.
36
Mechanical weathering
Breakdown of rock without changing its chemical composition.
37
How are fault scarps formed?
Plate moved forward.
Convection current caused pushed up land.
Rocks snapped/ tilted (over series of earthquakes) to create deep ridge known as fault scarp.
38
Example of fault scarp
Giggleswick scarp
39
Process of glaciation
Ice age creates glaciers which slowly move down valley.
They move/increase in size while eroding valley (plucking and abrasion) to make valley deeper/wider.
Postglacials results in wide and deep u shaped valleys
Can be used as upper course of river.
Weathering can make slopes less steep.
40
Physical processes that can affect a landscape
```
Weathering
Erosion
Deposition
Slope processes
Tectonic events
Geology
```
41
Scarp
Slope
42
Vale
Valley
43
Scree
Lose and angular pieces of rock caused by freeze thaw weathering
44
Misfit stream
Small stream which is tiny in comparison to the landscape
45
Alluvium
Sediment
46
Where is freeze thaw weathering more common?
| Why?
In north
| Wetter/colder climates
47
Freeze-thaw weathering process
Water in cracks/joints freeze (and so expand) putting pressure on the rock.
Melts, leaving wider/weaker crack
Repetition of this results in rock shattering and scree at slope foot
48
Slope process examples
```
Rockfall
Mudflow
Landslides
Glaciation
Soil creep
```
49
Rockfall
Rock free fall from steep cliffs due to loosening from freeze-thaw weathering
50
Mudflow
After heavy rain, if no vegetation to hold soil, saturated soil flows over impermeable subsoil.
51
Landslides
Ocasional rapid movement of earth/rock along concave plane due to heavy rain soaking overlying heavy rock and sliding over impermeable rock.
52
Soil creep
Wet and dry causes expansion/contraction of soil particles which slowly move down slope.
53
Anticline
Dome of folded rocks
54
The Weald
Once was anticline, is now alternating strata of more/less resistant rock (scarp and vale topography)
55
Scarp and vale topography
Landscape consisting of roughly parallel scarps w intervening valleys.
Resistant = form steep escarpments
Softer= lower / flatter
56
Examples of physical weathering
Temp change (expansion / contraction weakens rocks)
Wind/rain/waves (wear rock over time)
Freeze-thaw
57
Examples of biological weathering
Plant roots expanding rock faults
| Burrowing animals wearing down rocks
58
Chemical weathering
When a rock’s mineral composition is changed
59
Examples of chemical weathering
Acid rain dissolves alkaline rocks like limestone
60
Formation of dry valleys as a part of postglacial river processes
During/after ice age water froze in chalk (impermeable) so freshwater formed rivers/valleys which seeped through chalk when weather warmed.
61
Comparison of Lake District with The Weald
LD has rough, resistant and jagged igneous rocks while W has undulating hills w less resistant rock.
LD has cooler/wetter climate while W has warmer/drier climate.
LD has physical weathering while W has biological/chemical weathering.
Rockfalls/landslides/misfit streams occur in LD while soil creep/dry valleys occurs in W
62
How has agriculture changed the landscape for the bad?
Decline in arable farming= arable plant/wildlife reduction, scrub encroachment occurs due to traditional practice decline, agricultural chemicals = chalk grassland decline, farming harms environment, overgrazing=soil erosion=water pollution
63
Pastoral farming
Farming aimed at producing livestock
64
Arable farming
Where farmers low land, sow seeds and grow plants to harvest.
65
Conifer
A tree which bears cones/ needlelike leaves typically evergreen.
66
How has forestry affected the landscape for the worse?
May push out other vegetation
Debase landscape?
Deforestation leads to ancient tree extinction
67
Effects of settlements on landscape for bad
```
Loss of land distinctiveness
Decline in community facilities
Displacement of vegetation/wildlife
Pollution
Deforestation
Water/power consumption
```
68
Why’s coast important?
```
Wildlife
Trade
Beauty
Fishing
Energy
Jobs
Tourism
Transport
```
69
Transportation
Movement of eroded material up,down and along coastline
70
Deposition
When sea deposits material due to loss of energy
71
3 factors affecting waves
Wind duration
Fetch
Wind strength
72
Fetch
Distance travelled by wind
73
Destructive wave
High energy wave over long fetch, w high wave height in proportion to length.
Stronger backwash than swash
Erode coast and create flat beaches/cliff retreat/steep/narrow coast
74
Breaker of destructive waves
Plunging breaker
75
Constructive waves
Low energy waves w low heigh in proportion to length w stronger swash tan backwash. Deposits material on beach to create berms.
76
Breaker in constructive waves
Spilling breaker
77
4 types of erosion
Attrition
Abrasion
Hydraulic action
Solution
78
Hydraulic action
Compression of air within cracks in rocks to weaken it
79
Abrasion
Pieces of rock/sand grinding surfaces
80
Attrition
Smashing of rocks on shore so become smoother
81
Solution
Acids in sea water dissolve alkaline rocks (chalk/limestone)
82
6 stage of erosion along a joint
```
Joint (eroded headland)
Crack (hydraulic action/abrasion)
Cave (further erosion inside crack)
Arch
Stack
Stump (wave energy is focused)
```
83
Wave-cut platform formation
Wave-cut notch formed by hydraulic action/abrasion at base of cliff undercutting.
Cliff retreat as left unsupported and so collapses.
Wavecut platform is base of cliff left as cliff retreats inland.
84
Impact of uk climate on coastal erosion
4 seasons
SW prevailing winds bringing warm moist air from Atlantic and frequent rainfall, leading to weathering and coastal mass movement.
High storm frequency = high energy waves and mass movement (heavy rain)
85
Mass movement
Downhill movement of material under influence of gravity
86
What does mass movement depend on
Material involved
Amount of water in material
Nature of movement
87
Slumping process
When saturated rock (often clay). Slides down concave planes under the pull of gravity.
88
Sliding process
When loosened rocks/soil fall down slope in blocks of material together.
89
Coastal retreat
When coastline moves further inland affected by factors of erosion.
90
Long shore drift
When waves transport eroded material along the coast and deposit when they lose energy.
91
Long shore drift process
SW prevailing winds create diagonal swash (sediment E)
| Backwash due to gravity pulls sediment straight back down beach.
92
How are sandy beaches created
Low energy environments where constructive waves occur and deposit sediment to create gentle slope.
93
How are pebble beaches created
In areas of eroding cliffs, exposed to destructive waves producing pebbles from cliff by hydraulic action and abrasion. Is steeper.
94
Berm
Ridge of sand marking high tide
95
4 river transports
Suspension
Traction
Saltation
Solution
96
Suspension
Carrying of fine mud
97
Solution
Carrying of dissolved salts
98
Saltation
Transport off sand particles
99
Traction
Rolling/dragging of gravel and stones
100
Formation of a spit
When there’s a sharp bend at the coastline (like at mouth). Longshore drift transports sand/shingle past bend and loses energy so deposits material. Can be curved by strong winds.
Sheltered area behind is protected from waves and material accumulates to become mud flat/salt marsh.
101
Formation of a bar
If there’s no river currents to prevent longshore drift, deposition occurs in straight line across to Joplin land on other side.
Behind land forms marshland.
102
Formation of a tómbola
When deposition occurs behind an island w low energy environment so island becomes connected to mainland.
Forms bar across to island
103
How have human influenced coast
Settlements (villages lost to erosion)
Tourism (local economies, CBA protects tourism spots)
Infrastructure (high economic value, requires coast management w hard engineering)
Construction (dredging clears)
Agriculture (loss of land/fishin w sea levels/erosion
104
Why are coastal areas at risk from climate change?
```
Thermal expansion of oceans (heat=expansion)
Increased frequency/magnitudes of storms (low pressure fro storms n then surges. Greater temp contrast =stronger winds/storms)
Icecaps melting (sea levels)
POSTGLACIAL rebound (ice pressure released so land rises meaning other land sinks)
Land subsidence (instability of upper land due to changing of geology/foundations)
```
105
Hard engineering for coast protection
```
Groynes
Revetments
Gabions
Rock armour
Sea walls
```
106
Soft engineering for coast protection
Beach replenishment
107
Groynes pros/cons
Wooden structures perpendicularly lining coast to trap LSDsediment.
Cons: requires maintenance
Uneven beaches
V expensive
108
Revetments pros/cons
Wooden ramps lining coast absorbing wave energy while allowing backwash t drain away.
Cons: needs maintenance
Expensive
Prevents swimming
109
Gabions pros/cons
Cages of small rocks stacked absorbing wave energy.
Pros:lightweight/cheap
:(can be moved in storm
110
Rock armour pros/cons
Boulders lining coastline to absorb energy.
| Con: v expensive to transport
111
Sea walls pros/cons
Concrete recurred barrier reflecting energy.
Cons: v expensive
Technical to build
112
Beach replenishment pros/cons
Dredged sand pumped onto beach as natural barrier.
| Cons: needs to be repeated
113
Prevention methods
Hold the line
Advance the line
Managed retreat/strategic realignment
114
Hold the line
Stopping more erosion and protecting current coastline using mix of hard/soft engineering.
115
Advance the line
Reclaiming land and protecting it using hard/soft engineering.
116
Managed retreat/strategic realignment
Working w nature to allow gradual erosion using natural ecosystems.
117
Cost benefit
Total value of property defended/ total cost for 30 year defence
118
Ways to protect the cliffs
Rock groynes
Riprap
Cliff drainage
Cliff regrading.
119
Rock groynes
Traps sand to act as buffer zone for cliff
| :( expensive
120
Cliff drainage
Plastic drains prevent cliff saturation to prevent slumping
:( expensive
:( doesn’t work in large quantities or volumes
121
Cliff regrading
Change in Angle of cliff to increase stability/access.
:( involves work/ heavy machinery / tech
:( short term
122
Course
The path of a river as it flows downhill.
123
Long profile
How gradient changes over different courses
124
Cross profile
Shows cross section of river
125
Upper course characteristics
Hard and resistant rock, steepsided valley (vertical erosion), narrow/shallow channel (inefficient),
Low discharge, low load, slow velocity, large and angular stones,
Traction/saltation in high flow
126
What features occur in the upper course
Waterfalls, v-shaped valley
127
Middle course
Soft, less resistant rock, lateral erosion means wide valley, high velocity/efficiency, gentle slopes, wider/deeper channel so higher discharge,
Higher sediment load and more rounded rocks.
Suspension/solution
128
Middle course features
Meanders
129
Lower course
V wide/flat valley w less resistant rocks, high velocity river, little friction from smooth sides, more efficient, large discharge
Wide / deep channel, high load of well rounded, fine material.
Suspension / solution
130
Lower course features
Flood plains, large meanders, oxbow lakes, levees, deltas, estuaries
131
Load
Material transported in the river
132
Greater erosion characteristics characteristics
High energy/velocity
Deep channel
High gradient
Smooth channel
133
Lesser erosion channels characteristics
```
Friction
Rough channel
Low velocity/energy
Shallow
Inefficient
```
134
Drainage basin
Area of land drained by river
135
Catchment area
Area within drainage basin
136
Watershed
Edge of highland surroundings/drainage basin.
| Boundary between drainage basins
137
Source
Beginning/start of river
138
Tributary
Stream/smaller river which joins a larger stream/river
139
Mouth
Point where river comes to end, usually entering sea.
140
Confluence
Point at which 2 rivers/streams join
141
River discharge
Volume of water flowing in river per second
142
What’s discharge measured in
Cumecs (cubic meters per second)
143
Hydrographs
Graphs showing change in river discharge
144
Overland flow
Flow of water via surface run-off
145
Through flow
Flow of water through soil
146
Base flow
Flow of water through rocks
147
Peak discharge
Highest discharge in period of time
148
Basin lag time
Delay between peak rainfall and peak discharge
149
Rising limb
Increase in river discharge as water flows into river.
150
Recession limb
Decrease in river discharge as river returns to normal level
151
Factors affecting storm hydro graphs
Geology (impermeable=runoff)
```
Soil type (impermeable =runoff/ shallow=saturation)
Slope (steep =less infiltration)
Drainage basin type (circular=shorter lag time)
Antecedent conditions
```
152
Human factors affecting hydrographs
Urbanisation (impermeable =runoff / deforestation)
153
Factors of a flashy hydrograph
```
More flood chance
Short lag time
High discharge peak
Reach river fast
Steep rising limb
```
Possible impermeable surfaces/stormy weather/steep land/increased deforestation / urbanisation
154
Factors of a subdued hydrograph
```
Less flood chance
Long lag time
Low discharge peak
Reach river slowly
Shallow rising limb.
```
Possible afforestation, weak storm or narrow flood basin
155
Waterfall
Sudden drop along river course, forming when horizontal bands of resistant rock are positioned over exposed, less resistant rock.
156
Formation of a waterfall
1. ) soft rock erodes quicker than hard rock (creating a step)
2. ) erosion continues, hard rock is undercut forming overhang.
3. ) abrasion/hydraulic action creates a plunge pool
4. ) plunge pools gets bigger, increasing size of overhang until is no longer supported and so collapses and waterfall retreats upstream
157
Gorge
Steepsided valley where waterfall once was
158
Interlocking Spurs
Alternating, extending ridges, creating v shaped valley down which a winding course river flows.
159
Formation of interlocking spurs
In uppercourse vertical erosion cuts into valley.
| Areas of hard rock aren’t eroded meaning wasting river
160
Meander
Bend in the river course
161
Formation of meanders
1 water is pushed to outside of the bend w faster speed (so increased erosion via hydraulic action/abrasion)
2 lateral erosion undercuts bank to form river cliffs
3 water on inner bend is slower (deposition) to create a slip-off slope /river beach
162
Oxbow lake formation
Meander shape changes over time meaning no erosion narrows the neck of land within meander and they move closer together
During high discharge, river cuts across neck taking straighter/shorter route. Deposition occurs to cut off original meander.
163
Floodplain
Area of land covered in water when river bursts banks, caused by meanders on either side of river.
Erosion removes any interlocking spurs to create a wide and flat area on either side.
Height of flood plain increases as river deposits sediment (alluvium) for farming.
164
What three factors have affected the landscape
GEOLOGY
GLACIATION
TECTONIC PROCESSES
165
Landforms created by erosion at the coast
Wave-cut platforms
| Headlands and bays
166
Swash
Rush of seawater up the beach after the wave breaks.
167
Backwash
Seawater as it recedes down the beach
168
Landforms created by deposition at the coast
Spits
Tómbola
Bar
169
How do people affect the coast
Agriculture
Development
Industry
Coastal management
170
Hard engineering
Man-made structures built to control the flow of the sea and reduce flooding and erosion
171
Soft engineering
Scheme set up using knowledge of the sea and its processes to reduce effects of flooding and erosion
172
What is river velocity affected by
Gradient
Volume
Shape
Friction
173
How do you measure the velocity of a river
Float and a stopwatch
| Distance travelled/time taken
174
Infiltration
Water filtering into ground through pores in soil
175
Surface run-off
Water flowing across the surface
176
Transpiration
Moisture from plant/leaves being lost the atmosphere
177
Through flow
Water travelling through soil towards the river/sea.
178
Hard engineering methods in a river
Floodwalls
Floodgates
Demountable flood barriers
Embankments
179
Flood barriers
Temporary flood protection.
:) can be removed
:( expensive
:( risk won’t be put up in time
180
Floodwalls
Artificial barriers built along riverbanks designed to increase the height of the river banks and therefore increase capacity.
:( expensive and ugly
:( block view
181
Embankment
```
Hi banks built along the river banks usually made from earth/natural materials.
:) prevent flooding of built-up areas
:) prettier than flood walls
:( expensive
:( can break, danger of overflowing
```
182
Floodgates
```
Prevent flooding at very high tides on river estuaries.
:) shut when surge is forecasted
:) protect large areas of land
:( expensive
:( requires maintenance
```
183
Dredging
```
Making a river deeper so that it has the capacity to carry more water
;) reduces flood risk in built-up areas
;)Increases river capacity
:(Needs to be repeated frequently
:(Increases flood risk downstream
```
184
Flood relief channels
An extra channel allowing flood water to absorb.
:( expensive
:( can flood as well
185
Soft engineering at rivers
Floodplain retention
| River restoration
186
Floodplain retention
Strategy involving maintenance of the floodplain and not building on it
:)Slows floodwater down
:)Free
:)Maintains floodplains ability to hold water
:(Restricts development and can’t be used in urban areas
187
River restoration
Process of making the river more natural and allowing the floodplain to flood naturally.
:)Less risk of downstream flooding as discharge is reduced
:)Little maintenance required
:(Increases local flood risk
188
CMP
Catchment management plan produced for each drainage basin, must be sustainable.
189
Three stages of flood warning systems
Flood alert
Flood warning
Severe flood warning
(Communicated vía flood risk maps and alerts)
