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cambridge igcse geography > theme two > Flashcards

theme two Flashcards

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1
Q

volcano def

A

cone shaped mountained formed by eruptions of lava at the surface of the earth

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2
Q

crater def

A

a depression on the surface of a volcano, formed by volcanic activity, often circular in shape with deep sides.

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3
Q

vent def

A

the natural pipe or fissure that links the magma chamber to the crater or opening on the earths surface through which lava, ash and gases flow.

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4
Q

lava def

A

magma that has escaped from beneath the earth’s crust and has flowed onto the surface.

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5
Q

tectonic plates def

A

huge pieces of the earths crust that float and move on top of the much denser mantle below them

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6
Q

constructive/divergent plate boundary def

A

where two plates move apart, allowing magma to come to the surface as lava

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7
Q

magma def

A

molten rock found beneath the earths crust

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8
Q

magma chamber def

A

a large natural underground chamber of magma found within the surface of the earth beneath a volcano.

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9
Q

destructive/convergent plate boundary def

A

where two plates move towards each other

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10
Q

subduction def

A

when one plate sinks below another

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11
Q

hot spot def

A

a central part of the earths crust where plumes of magma rise to the earths surface

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12
Q

how can magma leave a volcano on to the earths crust

A

lava
volcanic bombs
very fine ash

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13
Q

what can volcanic eruptions be accompanied by

A

pyroclastic flows
lahars
earthquakes

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14
Q

composite/strato volcanoes

A

these are made from alternating layers of lava and ash as both come out of the vent during an eruption.

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15
Q

where do composite/strato volcanoes form

A

on destructive plate boundaries

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16
Q

shield volcanoes

A

these are made from lava. they from large volcanoes with gently sloping sides, sometimes hundreds of kilometres across before cooling and solidfying

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17
Q

where do shield volcanoes form

A

on a constructive plate boundary

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18
Q

dome volcanoes

A

these are also made from lava but the lava is acid and thicker and cools quicker. it does not flow very far before becoming solid and are steep sided and high.

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19
Q

active volcano

A

one that has recently erupted and is likely to again.

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20
Q

domant volcano

A

one that has erupted in the last 2000 years and may erupt again. hard to predict.

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21
Q

extinct volcano

A

long since finished erupting and has cooled down

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22
Q

earthquake def

A

a sudden and often violent shift in the rocks forming the earth’s crust, which is felt at the surface.

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23
Q

fault line def

A

a fracture or break in the earths surface along which rocks have moved alongside each other

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24
Q

focus def

A

the location of the actual source of an earthquake below the ground surface; also called the origin

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25
Q

conservative platae boundary def

A

where two plates are sliding alongside each other

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26
Q

epicentre def

A

location on the surface of the earth above the focus or origin of the earthquake

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27
Q

tsunami def

A

powerful, devastating waves at the coast caused by an undersea earthquake or volcanic eruption that displaces the water lying above it

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28
Q

seismometer def

A

an instrument that meaures movement of the ground, including the seismic waves generated by earthquakes and volcanic eruptions

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29
Q

seismic waves

A

waves of energy that travel through the earths layers as a result of earthquakes, volcanic eruptions, magma movements and large landslides

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30
Q

moment magnitude scale and richter scale def

A

numerical scales showing the size or magnitude of an earthwuake based on readings from a seisometer

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31
Q

mercalli scale def

A

a scale showing the effect of an earthwuake on the earths surface

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32
Q

aftershock def

A

a smaller earthquake following after the main earthquake

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33
Q

fold mountains def

A

a long, high mountain range formed by uplifting and folding of sediments

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34
Q

convection currents def

A

differences in temperature of material beneath the plates of the earth’s crust leads to the creation of currents to transfer the heat. these currents move the plants above them.

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35
Q

subduction zone def

A

the zone where one tectonic plate sinks under another

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36
Q

island arc def

A

a chain of volcaniv islands located above a subduction zone at a tectonic plate boundary

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37
Q

tephra def

A

rock fragments and particles ejected by a volcanic eruption

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38
Q

fumarole def

A

an opening in or near a volcano, through which gases, such as sulphur dioxide, are emitted

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39
Q

impacts of earthquakes and volcanoes on people

A 
loss of life
cutting of basic necessitites
collapse of bildings
infrastructure damage
loss of crops
fish can be killed
spread of disease
loss of jobs and businesses
higher insurance premiums
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40
Q

primary effects

A

direct result of the earthquake or volcanic eruption

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41
Q

secondary effect

A

result of primary effects

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42
Q

what does the amount of damage caused by earthquakes depend on

A 
strength
depth
distance from epicentre
geology
building construction and design
space between buildings
population density
time of day
secondary hazards like landslides
contamination
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43
Q

opportunites granted by volcanoes

A

volcanic soils often fertile
geothermal power
raw materials / resources
attract tourists

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44
Q

how to reduce impact of volcanoes and earthquakes

A

improved technology
mapping high risk areas
improvind building design
ensuring emergency drills are in place

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45
Q

how can scientists predict volcanic eruptions

A 
seismometers
tilt meters
thermometers
gas sensors
satellites
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46
Q

swash def

A

the movement of a sea wave up a beach after the breaking of a wave

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47
Q

backwash def

A

the movement of a sea wave down the beach after the breaking of a wave

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48
Q

hydraulic action

A

the weight and force of a wave crashing against a cliff removes particles of rockss from the cliff. also includes the process where air is trapped by a wave in a cliff and the enormous hydraulic pressure this creates opens up the clfif further.

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49
Q

abrasion

A

where rocks and sand are picekd up by a wave and thrown against the cliff

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50
Q

solution

A

some minerals are put into solution by weak acids found in seawater

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51
Q

attrition

A

rocks on the beach are rolled up and down the beach by swash and backwash. as this happens they collide with each other and become smaller and rounder as a result

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52
Q

longshore drift def

A

the movement of material along a beach transported by wave action

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53
Q

spits def

A

ridges of sand or shingle attached to the land but ending in open sea

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54
Q

bars def

A

ridges of sand or shingle acrss the entrance of a bay or river mouth

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55
Q

tombolos def

A

spits connecting an island to the mainland

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56
Q

groynes def

A

wooden, stone or concrete barriers built perpendicular to the coast in order to break waves and reduce the movement of sediment along the beach

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57
Q

constructive wave action

A

swash stronger than backwash so more sand and shingle will travel up the beach

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58
Q

destructive wave action

A

swash weaker than backwash so more sand and shingle will be moved down offshore

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59
Q

salt marsh def

A

an area of mudflats formed when sediment is deposited in the low wave energy area behind a spit

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60
Q

cliff notch def

A

a small overhang formed at the base of a cliff by wave action

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61
Q

wave cut platform def

A

a wide, flat area of rock at the bottom of cliffs seen at low tide

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62
Q

headlands def

A

areas ofmore resistant rock jutting out from the coast into the sea

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63
Q

cave def

A

a hollow at the base of a cliff which has been eroded by rocks

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64
Q

arch def

A

a rock bridge formed at a headland that has been partly broken through by the sea

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65
Q

stack def

A

an isolated column of rock at the end of a headland formed after a stack has collapsed

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66
Q

bay def

A

a broad coastal inlet, often curved and with a beach, between two headlands

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67
Q

what will happen if the coastline alternates between soft and hard rock

A

differntial erosion will take place resulting in a disconcordant coastline

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68
Q

wherer do salt marshes form

A

sheltered bays and estuaries in the protected area behind a spit or tombolo

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69
Q

coral reef def

A

a ridge of rock near the surface of the sea, formed by frowth and deposit of coral

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70
Q

types of coral reef

A

barrier
fringe
atoll

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71
Q

conditions for coral reefs to form

A 
temp has to be 23-25 degrees
depth of water had to be less than 25cm
water has be clear for lots of sunlight
low salinaty
low sediment
high energy wave action for freshly oxygenated water
exposure to air
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72
Q

where are mangerove swamps found

A

along coastliens between 30 north and 30 south of the equator.

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73
Q

magrove swamps def

A

tidal swamps that are dominated by mangroves (shrubs or small trees with numerous tangled roots that grow above ground

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74
Q

adaptations of mangroves

A 
low oxygen conditions 
low salt intake in tree
low water loss
aerial roots to absorb nutrients
the seeds float
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75
Q

roles of mangroves

A

coastal protection
breeding ground
source of food, medicine and raw materials

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76
Q

managing impacts of coastal erosion

A

sea walls
revetment
gabions

rock armour
groynes
beach nourishment

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77
Q

assessments on how to defend a coast:

A

cost-benefit analysis
environmental impact assements
shoreline management plan

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78
Q

tropical storm def

A

areas of very low pressure in low latitudes, with strong winds and heavy rains

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79
Q

ICZM def

A

integrated coastal zone management
the management of the coast using an integraed approach, taking into account all aspects of the coastal zone, including geographical and political boundaries

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80
Q

littoral cell def

A

a length/section of the coast that is isolated from adjacent sections of coast and has its own sources

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81
Q

weather def

A

the state of the atmosphere at any paticular moment in time

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82
Q

climate def

A

a description of the averages and extremes of weather variables of an area over an extended period of time

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83
Q

stevenson screen def

A

a container in which weather/meteorological instruments are placed

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84
Q

isohyet def

A

a line on a map joining places of equal rainfall

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85
Q

how is weather data collected

A 
stevenson screen
rain gauge
maximum minimum thermometer 
wet and dry bulb thermometer
barometer
anemometer
wind vanes
cloud cover
sunshine recorder
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86
Q

diurnal range def

A

the daily range of temperature

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87
Q

relative humidity def

A

the amount of water vapour (moisture) in the air, expressed as a percentage of the maximum amount of water vapour that the air could hold at a given time

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88
Q

stevenson screen

A

box that contains weather/meteological for protection

89
Q

rain guages

A

many characteristics for an accurate reading

90
Q

maximum and minimum thermometers

A

measures diurnal range

91
Q

wet and dry thermometers

A

measures relative humidity by measuring the temperature of the air and the temperature of the air if there was 100% humididty

92
Q

sunshine recorder

A

measures the length of time that the sun has shone during the day in between periods of cloud cover, fog or when the sky has been obscured by smoke or some other form of pollution

93
Q

barometer

A

measures atmospheric pressure in millibars (mb)

94
Q

anemometers

A

measure the speed of wind

95
Q

wind vanes

A

indicate wind direction

96
Q

cloud cover

A

the amount of cloud covering the sky is measured in oktas

97
Q

characteristics of an equitorial climate

A 
low range of monthly mean temps
constant high temp
high rainfall
high humidity
high levels of soil moisture
98
Q

equitorial climatae def

A

the constantly hot and cold wet climate of regions near the equator

99
Q

insolation def

A

a measure of the amount of solar energy received per square centimetre per minute at the earths surface

100
Q

prevailing winds def

A

the direction from which the wind blows into an area for most of the year

101
Q

trade winds def

A

the prevailing pattern of easterly surface winds found blowing between the tropics and the equator

102
Q

convectional rainfall def

A

this occurs when land is heated up and the warm air goes above it rises, cools, and condenses to give clouds and rains.

103
Q

average monthly temperature in the desert

A

over 29 degrees in the hot summer season but 10 degrees in the cool winter season

104
Q

daytime temps in the desert

A

over 38

105
Q

nighttime temps in the desert

A

under 5

106
Q

how much water does a desert get a year

A

under 250mm

107
Q

humidity in the desert

A

25-30%

108
Q

climate graph def

A

a graph showing the average weather for a period of time for a named location. temperature is shown as a line graph and precipitation as a bar graph.

109
Q

hot desert climate def

A

the constantly hot and dry climate regions between 15 to 30 degrees north and south of the equator

110
Q

latitude def

A

this is used to locate the north south position of a point on the earths surface. latitude ranges from 0 at the equator to 90 at the poles. lines of altitude run east-west as circles parallel to equator

111
Q

rain shadow def

A

a region having little rainfall because it is sheltered from prevailing winds by a range of hills or mountains

112
Q

ocean current def

A

any permanent or continuous, directed movement of ocean water that flows in one of the earths oceans

113
Q

factors that influence the characteristics of the hot desert climate (7pts)

A

located in latitudes from 15 to 30 north and south of the equator.
high atmospheric pressure
long distance from oceans
prevailing winds
in areas of rain shadow
some have cold ocean current flowing past them
relief can affect the humidity and rainfall.

114
Q

altitude def

A

the height above sea level

115
Q

coriolis effect def

A

this causes a deflection in global wind patterns. the anticlockwise rotation of the earth deflects winds to the right in the northern hemisphere and to the left in the southern hemisphere

116
Q

where are rainforests found

A

amazonia
central africa
indo-malaysia

117
Q

HADLEY

A

CELL

118
Q

ecosystems def

A

communities of biotic and abiotic things interacting with each other in an area

119
Q

adaptations def

A

changes and mechanisms that help organisms survive in their ecological habitat

120
Q

biodiverse def

A

describe the varity of organisms present in different ecosystems

121
Q

describe the emergent layer (45-55m)

A

tall, large trees above the general canopy
branchless
can withstand hot temperatures and strong winds
some have buttress roots for support
might have lianas/epiphytes etc growing on them

122
Q

epihytes

A

grow on trees and use the dead leaves and water for nutrients

123
Q

describe the canopy layer (30m)

A 
smooth oval leaves with drip tips
thick and dense
very little light gets through to the roots below
home to 50%of the earth's plant species
food is abundant
124
Q

the under/sub canopy layer (15m)

A

little light so plants have large leaves

lots of insects

125
Q

shrub layer (3-4m)

A

very dark (5% of sunlight reaches here)
tree ferns and small shrubs
large leaves to collect any light

126
Q

floor ground layer (0m)

A 
very dark (1% of sunlight reaches) 
things decay quickly
127
Q

deforestation def

A

permanently removing forest so the land can be used for something else.

128
Q

slash and burn def

A

a form of agriculture where the natural vegetation is cut down and burnt a method of clearing the land for cultivation

129
Q

reasons and impacts of deforestation

A 
logging
plantation agriculture
cattle ranching
new settlement
mining
HEP, dams and reservoirs
foods and spices
climate change and carbon sinks
loss of indigenous people
130
Q

wadi def

A

the bed or valley of a stream in regions of south-western asia and northern africa that is usually dry except during the rainy season

131
Q

oasis def

A

an isolated area of vegetation in a desert, typically surrounding a spring or similar water source, such as a pond or small lake. they also provide a habitat for animlas and people if the area is big enough.

132
Q

xerophytes def

A

a species of plant that has adapted to survive in an environment with little liquid water.

133
Q

plant adaptations for water (desert)

A

some store water in their leaves, roots and stems - like the prickly pear cactus.
long tap roots (60m)
wide-spreading shallow roots to absorb water when it rains before it evaporates
small, spiny leaves which give foff less moisture than leaves with greater surface areas

134
Q

dersertification def

A

a type of land degradation in which a relatively dry area of alnd becomes increasingly arid, typically losing its sources of water as well as its vegetation and wildlife. caused by a variety of factors, such as through climate change and through the overexploitation of the land and its water resources

135
Q

how to reduce desertifiation

A

trees are being reintroduced to the desert to stabilise the sand and act as wind breaks. the choice of trees and shrubs is extremely important - need to be able to survive, be low maintence and have other uses.

136
Q

describe the impacts of an earthquake on a named area you have studied

A

nepal: 7.8 magnitude, april 2015, major fault line under indian plate under eurasion plate
9000 died
9000 schools destroyed
damages from $5 billion to $10 billion

137
Q

describe the impacts of a volcanic eruption on a named area you have studied

A

eyjafjallajokull: 500m fissure, dissolved gases in molten rock along with steam generated from melting ice caused a large column of volcanic ash
airlines lost £130 million / day
Nissan forced to stop production because they could not import parts from ireland
major flood in iceland - 700 people forced to evacuate

138
Q

for a named example which you have studied, explain why people live close to a volcano

A

eyjafjallokull:
fertile soil - (volcanic eruptions deposit the necessary minerals for a steady supply of nutrients) 1/5 of total are of iceland suitable for fodder production
tourism - eyjafjallajokull visitor centre
energy - nearly 100% from geothermal

139
Q

for a named example of a volcanic eruption you have studied, describe its effects on people and the natural environment

A

eyjafjallajokul:
700 to evacuate due to flood
ash fall poisoned animals in nearby fields
7km of volcanic ash plumes

140
Q

for a named area of hot desert you have studied, explain why the climate is hot and dry

A

sahara:
prevailing wind blows from the northeast takes moisture from the air and leaves dust (therefore aridness)
hadley cell: in the 25 degrees either side of the desert the atmosphere has high pressure. this forces the low pressure air closer to the ground, and as it already has little moisture the sun heats it easily. the heat then transfers to the ground.
rainshadow effect: as air makes contact with moisture, it rises above it, therefore the moisture precipitates onto the mountain peaks, leaving little to fall on the desert

141
Q

for a named (hot) area you have studied, describe and explain the characteristics of its natural vegetation

A

saguaro cactus: waxy cuticles to prevent water loss by evapaotranspiration
acacia tree: umbrella shaped top to collect all the sunlight and water, and force plants to grow elsewhere to get minerals and nutrients
tap roots: long roots of 7-10m to get as much water as possible

142
Q

for a named area you have studied, explain how the wildlife are adapted to the environment

A

fennec fox: thick furry feet for traction and protection
horned desert viper: horns over eyes to protect from sand and can bury itself to escape from heat and predators
sandfish lizard: lower jaws countersunk behind snout and upper jaws to stop sand getting in mouth

143
Q

describe the impacts of deforestation of tropical rainforests on the global natural environment. refer to named areas affected.

A

loss of biodiversity and habitats
amazon has 80% of worlds documented land species’
climate change increase
amazon absorbs 2.2 billion tons of CO2 a year
desertification
fertile land becomes desert, after deforestation vegetation is much harder to grow

144
Q

for a named area of tropical rainforest you have studied, explain how its characteristics are influenced by equatorial climate

A

amazon
proximity to equator - 214 miles
tropic of cancer and capricorn - hadley cell
close to sea on east so prevailing wind takes moisture and leaves dust

145
Q

for a named area of tropical rainforest you have studied, describe the impacts of latge scale deforestation on the local environment

A

flash floods
football field cleared / minute
soil erosion
top soil thin and recives most nutrients. deforestaiton removes these
damage to local ecosystems
microorganims destroyed through burning
less plants grow, less evapotranspiration

146
Q

for a named coast you have studied, explain what is being doen to manage coastal erosion

A

new forest coastline, uk
rock revetments at barton on sea, prevents flooding and futher erosion
sea wall from lymington to keyhaven, decrease wave power
beach replenishment: sediment taken away from areas where its reguarly deposited and placed in an area where it is needed

147
Q

for a named area you have studied, describe the impacts of a tropical storm

A

hurricane floyd
4 million evacuated due to floods
500 roads made impassable (jobs)
insurance companies forced to pay out $460,000

148
Q

drainage basin def

A

the area of land drained by a river and its tributaries. known as river basin or river catchment area

149
Q

river mouth def

A

where the river ends when it meets a body of water such as the sea or a lake

150
Q

watershed def

A

the boundary of a drainage basin

151
Q

tributary def

A

a stream or small river that joins a larger one

152
Q

confluence

A

the point where two or more rivers meet

153
Q

discharge of a river def

A

the volume of water passing a point or location along the river channel in a given time. it is usually measured in cubic meters per second (cumecs) at a gauging station in a river

154
Q

what does a drainage basin do

A

all the precipitaiton that falls within a drainage basin will attempt to make its way towards the river channel (underground or surface) and eventually to river mouth.

155
Q

what is the input

A

the water added to a drainage basin in the form of precipitation

156
Q

store def

A

surface or underground locations in a drainage basin that hold and contain water

157
Q

what is the output

A

the losses of water from the drainage basin in terms of evaporation, transpiration and river/channel flow

158
Q

aquifer def

A

a body of underground rock thatthrough its rock type or structures, holds water. this water can be abstracted from the rock by drilling wells and boreholes.

159
Q

what is evaporation

A

the loss of water as it transfers from liquid to gas. higher the temp, higher the rate of evaporation

160
Q

what is transpiraton

A

loss of water vapour from stomata in the leaves. rates depend on amount and type of vegetation

161
Q

what i evapotranspiration

A

combined loss of water from evaporation and transpiration

162
Q

what is dripflow

A

leaves and trees intercept precipitation and it then flows off leaves.

163
Q

what is stemflow

A

the precipitation from dripflow flows down the stems of trees and plants

164
Q

waht is inflitration

A

when intercepted water is released slowly into the land surface ,allowing it to enter into the soil.

165
Q

impermeable def

A

these rocks are watertight and do not allow water to pass through

166
Q

infiltration capacity def

A

the rate at which water infiltrates the land surface

167
Q

when might water have to flow over land (overland flow)

A

when the soil and rock are saturated
impermeable land surface
when there is lots of trees and vegetation

168
Q

porous def

A

describes rocks that contain many small air spaces

169
Q

permeable def

A

describes rocks that allow water to pass through them via cracks, faults, joints and bedding planes

170
Q

what is percolation

A

when water has infiltrated the ground and now flows/percolates through the underlying rock by gravity. rate depends on how porous the soil/rock is and how permeable the rock is

171
Q

what is the top of an aquifier called

A

the water table

172
Q

what is throughflow

A

when water is moving laterally as throughflow

173
Q

what is groundwater flow

A

when water had inglitated and percolated into the rock below the soil and then moves laterally.

174
Q

where does groundwater flow usually increase

A

where the soil and rock are very porous and permeable and during periods of steady rainfall

175
Q

what is weathering

A

the actual breakdown of rock where it is found by physical, chemical, biological processes.

176
Q

hydraulic action def

A

Where the weight and force of the water flowing in the river removes particles of rocks from the river channel’s bed and sides.

177
Q

abrasion def

A

Where the river’s bedload (boulders, pebbles, gravel, sand and silt) as it rolls, bounces and collides with the channel bed and sides, removes particles of rock from the channel bed and sides.

178
Q

solution def

A

Where some minerals (mainly the carbonate minerals found in rocks like limestone and chalk) are put into solution b the weak acids include carbonic acid which is formed as carbon dioxide gas in the atmosphere joins with rainwater and this has a great impact on the carbonate rocks and limestone in paticular

179
Q

attrition def

A

Process which does not erode the river channel bed and sides, but breaks up the river’s bedload. It takes place when the rocks on the bed of the river are rolled along and they collide with each other and become smaller and rounder as a result. This means that the average size of rock particle (sediment) becomes smaller as it moves down towards the river mouth

180
Q

traction def

A

Where the larger, heavier material that make up the river’s bedload (boulders, pebbles, and gravel either through rolling or bouncing are in actual contact with the river bed) is rolled along the river bed.

181
Q

saltation def

A

Where the lighter materiak that makes up the river’s bedload (gravel, sand and silt) is bounced along the river bed.

182
Q

suspension def

A

Where the smaller, lighter material that makes up the rivers suspended load (clay-size - a particle that is less than 0.02mm in diameter) is carried/suspended by the river

183
Q

solution def

A

Where dissolved material that makes up the river’s solute load is moved by the river in solution.

184
Q

weathering def

A

the breakdown of rocks in their locatiosn

185
Q

erosion def

A

the removal of weathered material from the land by water, ice or wind

186
Q

bedload def

A

fragments of rock which have come into contact with the bd of the river channel during their transportation

187
Q

floodplain def

A

an area next to a river that would be affected by flooding if the river overflowed its banks

188
Q

delta def

A

a landform, often triangular in shape, which develops where a river meets a slow body of moving water such as a lake or ocean. sediment builds up above the water level forcing the river to split into distributaries to form a delta

189
Q

gradient def

A

how steep a slope, river channel or valley is

190
Q

when does the velocity or speed of a river decrease

A

when the gradient of a river decreaes
when the river channel bed becomes rougher and shallower
when the river meets a large, static bidy of water such as the sea or a lake is slowed/halted.

191
Q

long profile def

A

the shape and gradient of the river channel from soruce to mouth

192
Q

cross section def

A

the shape across the river valley, from one side to another

193
Q

source def

A

the starting point of a river, often a spring, melting glacier or wetland

194
Q

v-shaped valley def

A

a valley with a v-shaped cross profile

195
Q

vertical erosion def

A

where a stream or river erodes the river channel bed at a faster rate thatn the channel or valley sides, often leading to a narrow, v-shaped , valley

196
Q

lateral erosion def

A

where a stream or river erodes away the sides and banks on each side of the river channel.

197
Q

upper course valley

A 
narrow
steep sided
v-shaped
large angular boulders and stones
slow flow
rough channel bed
predominantly vertical erosion
smaller discharge
198
Q

lower course

A 
wide valley
larger channel
river channel often next to a floodplain
smaller, rounder rocks (sand)
faster flowing
predominantly lateral erosion
199
Q

middle course

A

comibation of the upper and middle features

200
Q

how does the discharge of a river change through the courses

A

will increase from the source to the mouth as smaller tributary channels add more water to the main channel

201
Q

how does velocity change through a river

A

increase because as discharge increases there is less friction so faster flow

202
Q

how do waterfalls form: differential erosion

A

where a layer of more resistant rock runs across the river channel. the softer, less resistant rock is eroded at a faster rate, causing a drop in the river bed.

203
Q

how do waterfalls form: sea level

A

sea level drops leaving the mouth of the river suspended above the lower sea level. knick point

204
Q

when do potholes start to form

A

when a weakness or crack or fault line is exposed in the rock in the riverbed and differential erosion takes place

205
Q

meander def

A

a bend in a river

206
Q

river cliff/bluff

A

a steep section of the river bank caused by fast-flowing water eroding the outside of the bank of a meander

207
Q

slip-off slope/point bar

A

a gentle slope on the inside of a meander formed by deposited on the inside of a meander where the river flows more slowly and less energy.q

208
Q

oxbow lake def

A

a lake, often semi-circular in shape in a river floodplain, where a meander has been cut off from the river channel

209
Q

bankfull discharge

A

the river discharge when the river channel full to the top of its banks and is just about to spill onto its floodplain.

210
Q

alluvium

A

sediments which are depositied by rivers

211
Q

levee

A

a raised bank of sediment along the sides of a river channel

212
Q

what happens to a meander ove rtime

A

its neck becomes very narrow. the river may break through the neck - often during high flow conditions. this may result in a section of the river channel being isolated from the main river chanel to form an oxbow lake. with time these dry out to form oxbow scars.

213
Q

what is the outside bank of the river called

A

river cliff or bluff

214
Q

what is the inside bank of the river called

A

the slip off slope or point bar

215
Q

describe the river cliff/bluff

A

deep, fast flowing and often undercut by river, large sediment size

216
Q

describe the slip off slope or pointbar

A

shallow, slow flowing. small sediment size

217
Q

for a named volcano you have studied, explain the causes of an eruption

A

eyjafjallajokull
North american and eurasion plate
The two plates are moving apart (constructive) due to ridge push along the Mid-Atlantic Ridge. As the plates move apart, magma fills the magma chamber below Eyjafjallajokull.

218
Q

describe the causes of an earthquake on an area you have studied

A

caused by a sudden thrust, or release of built-up stress.
Indian Plate is diving underneath the Eurasian Plate.
magnitude of 8.1

cambridge igcse geography (5 decks)

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