Coasts KQ 3 Flashcards

1
Q

What could cause a change in global temperature?

A
  • variations in the earths orbit around the sun
  • variations in the amount of energy produced buy the sun
    -changes in the composition of the earths atmosphere due to major volcanic eruptions
    -variations in the tilt of the earths axis
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2
Q

if there is a fall in global temperature how will precipitation be affected ?

A

more precipitation will fall as snow

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3
Q

if there is a fall in global temperature what will there be lower rates of ?

A

evaporation , condensation and then precipiatation

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4
Q

if there is a fall in global temperature what will more water be stored as ?

A

snow and ice (in glaciers and ice sheets )

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5
Q

if there is a fall in global temperatures where will less water be stored in ?

A

oceans

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6
Q

what is thermal contraction ?

A

as temps fall , water molecules contract leading to an increased density and reduced volume

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7
Q

what are eustatic changes ?

A

changes in the volume of water in the global ocean store

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8
Q

when was the tyrrhenian glacial period ?

A

130 000years ago

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9
Q

how high was the sea level 130 000 years ago ?

A

20m

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10
Q

when was the riss glacial period ?

A

108 000 years ago

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11
Q

how low was sea level 108 000 years ago ?

A

-85m

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12
Q

what period is the flandrian trangsression ?

A

25,000 years ago to now
(sea l;evel rising to present day )

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13
Q

names some features on an emergent coastline ?

A

abandoned cliffs
active beach
marine terrace
raised beach
abandoned waterfalls

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14
Q

what is falling sea level ?

A

during glacial periods the ocean height is reduced because ocean water is stored as ice upon the land surface

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15
Q

what is a raised beach ?

A

a deposit of sand which is now above sea level

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16
Q

what is a marine terrace ?

A

a rock terrace where a wave cut platform has been left inland by falling sea levels (or uplift of the land )

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17
Q

what is an emergent landform ?

A

found inland some distance from the modern coastline as a result of a fall in sea level

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18
Q

what is the plan view of a ria ?

A

wide and branching plan view

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19
Q

what is the long profile of a ria ?

A

gentle gradi8ent and the depth is similar all the way along it

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20
Q

what is the cross section of a ria ?

A

shallow cross section
slightly deeper in the middle

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21
Q

what are rias useful for >?

A

ideal for harbours and mariners because it is sheltered

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22
Q

when did rias form ?

A

during the post glacial sea level rise of the flandrian transgression

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23
Q

what is a ria ?

A

A river valley that’s been flooded by the eustatic rise in sea level, usually where a river meets the ocean📍

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24
Q

what are valley sides like of a ria ?

A

gently sloping
been formed by mass movement and weathering

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25
Q

what is an example of a fjord in new Zealand?

A

Milford sound , new zealand

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26
Q

what are fjords used for >?

A

transport
natural sheltered habour

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27
Q

what is a fjord ?

A

submerged glacial valley

28
Q

what is the cross section of a fjord like ?

A

steep valley sides
water = uniformly deep
U Shaped
sometime deep as 1000 m
deeper than a ria

29
Q

what is the long profile of a fjord like ?

A

straighter long profile
shallower section at the end known as the threshold
extra bit of rock at the end

30
Q

how long is the sogne fjord in Norway ?

A

200km long

31
Q

How was a fjord formed ?

A

interlocking spurs were removed as a u shaped valley was carved out by the glacier which formerly occupied the valley

32
Q

what is the plan view of a fjord like ?

A

straighter plan form than a ria

33
Q

how does a ria form ?

A

the floodplain is completely drowned and only the middle and upper parts are exposed

34
Q

what are the processes involved in the formation of a ria ?

A

formed by fluvial erosion
weathering and mass movement shape the valley sides
underlain by fluvial material deposited during the Flandrian transgression

35
Q

What processes are involved in the formation of a fjord ?

A

glacial erosion (abrasion and plunging)
freeze thaw weathering
high marine erosion rates

36
Q

what is Chesil beach ?

A

a bar of shingle that joins portland bill to the mainland

37
Q

how was Chesil beach formed ?

A

rising sea levels pushed pebbles in a north east direction to create Chesil beach

38
Q

what may shingle beaches also form ?

A

may form tombolos and bars

39
Q

Is falling global temperatures emergent or submergent ?

A

emergent

40
Q

is rising global temperatures submergent or emergent ?

A

submergent

41
Q

What will rising sea levels lead to ?

A

Accelerated erosion of cliffs and beaches
Flooding of urban areas
Salinisation of agricultural land
Salinisation of freshwater sources
Widespread destruction of habitats

42
Q

What are some examples of responses to rising sea level ?

A

Sea walls
Grounds
Artificial raising of land behind walls
Retreat - abandon land to sea
Upstream draining of dammed lakes

43
Q

What does peri glacial mean ?

A

When it was really cold (just after a glacial period)

44
Q

What does post glacial mean ?

A

Present day temp

45
Q

What is an isostatic change ?

A

Due to rising or sinking of the earths crust caused by either tectonic movement or removal or addition of a great weight (e.g. ice sheeet)

46
Q

What is post glacial rebound ?

A

The rise of a land mass after the removal of the huge weight of ice sheets during g the last glacial period , which caused isostatic depression

47
Q

Are isostatic changes localised or global ?

A

Localised

48
Q

Are eustatic changes localised or global ?

A

Global

49
Q

What are the peri glacial modifications of emergent landforms ?

A

Frost weathering causing rock fall from the cliff face
Cryoturbation (frost churning) has disrupted the layers of the permafrost
Layers of debris fo=room frost shattering

50
Q

What are the post glacial modifications to emergent landforms ?

A

Development of vegetation cover on some surfaces
More chemical weathering of the limestone by carbonation
Biological weathering by increasing numbers of limpets

51
Q

What do limpets do ?

A

Provide a living substrate one which micro-habitats of algae and barnacles can survive

52
Q

What are the futur modifications of emergent landforms ?

A

Sea level rise could mean increases action wave processes

53
Q

How much is sea level rising each year ?

A

0.6mm

54
Q

What does not directly affect sea level rise and why ?

A

Melting sea ice
Already si placing water

55
Q

What is the upper estimate of sea level rise by 2100 /

A

0.98mm

56
Q

Scandavia and Scotland dare rising relative sea level because of which process ?

A

Isostatic rebound

57
Q

How and why sea level changed to flood The Valley to create a fjord ?

A

Thermal expansion - water molecules increase
Flandrian transgression
Glacial ice caps melt which creases sea level

58
Q

What happened 20,000 years ago in terms of isostatic sea level change ?

A

Huge ice sheet covered NW Scotland
This huge weight pressed the NW section of the plate down in to the mantle and SE England rose

59
Q

what is happening present day in terms of isostatic sea level change ?

A

Ice sheet has melted
The weight has been removed and the NW of Scotland is sprinting back , but the SE is sinking

60
Q

What is there in the NW of Scotland ?

A

Is still rebounding
Emergent landforms

61
Q

What is there is SE England ?

A

Still sinking
So flooding
Submerge the landforms

62
Q

What will a 1 degree fall in mean global temp result in ?

A

Sea level to fall by 2m

63
Q

What will a 1 degree rise in the mean global temp cause ?

A

Sea level rise of about 2m

64
Q

Give an example of a ria ?

A

Kings bridge estuary , south Devon

65
Q

How long is kings bridge estuarary in km ?

A

8.6 km