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Geog Coast BK 3 Sea Level Change > Sea Level Change > Flashcards

Sea Level Change Flashcards

1
Q

where is the fastest speed of change at a coastline found

A

at the shoreline

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2
Q

over the past 2 million years what has been the cause of major fluctuations in sea level

A

glaciation

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3
Q

when do our current coastlines date from

A

6000 years ago

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4
Q

what are the four different time scales that Cowell and Thom identified

A

Instantaneous
Event Time scale
Engineering time frame
Geological time scale

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5
Q

describe the instantaneous time scale

A

landforms are affected by changes operating in a single cycle like waves or tides

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6
Q

describe event time scale

A

these operate across a time span from an individual event through to seasonal variations

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7
Q

describe the engineering time frame

A

when fluctuations take place over longer time scales, from years to decades

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8
Q

describe geological time scale

A

from decades to millennia

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9
Q

what landforms could be affected by instantaneous, event and engineering time scales

A

instantaneous = sand beach
event= sand dunes
engineering = headlands

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10
Q

list some factors that affect the rate of change at the coast

A

locations
climate
wave energy
fetch
wind speed
rock type
concordant and discordant coasts
aspect
seaward/landward dip

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11
Q

why is geology a significant factor in terms in effecting the rate of change

A

it can determine the speed of erosion and the supply of sediment for deposition

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12
Q

when did the last ice age end

A

around 11,500 years ago

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13
Q

what is the period we are in now called

A

Holocene

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14
Q

what is transgression

A

the melting of ice and the retreat of glaciers polewards led to a rise in sea level and a retreat of coastlines

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15
Q

when was the last transgression in britain and what was it called

A

6000 years ago, called Flandrian

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16
Q

what did Flandrian cause

A

the north sea basin and the english channel to be flooded

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17
Q

what is the opposite of transgression

A

regression

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18
Q

what is regression

A

something that takes place at the end of glacial periods, when sea levels fall because ice is locked up in glaciers and ice sheets

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19
Q

how does tectonic activity impact sea level

A

active earthquakes or volcanos cause the crust to be displaced causing the emergence or submergence of land

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20
Q

what are two other factors that impact sea level change

A

time and wind

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21
Q

what is isostatic sea level change

A

when the level of the land changes

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22
Q

what is eustatic sea level change

A

where the level of the sea changes

23
Q

what is causing eustatic sea level rise now

A

global warming causing the melting of ice sheets and glaciers etc

24
Q

what is glacio-eustacy

A

changes in sea level resulting from glaciation

25
Q

how do ice ages impact eustatic levels

A

in an ice age where water is frozen in ice sheets and glaciers this causes a eustatic sea level fall, but when this melts in warmer inter-glacial periods this cause eustatic sea level rise

26
Q

what was the most recent ice age called

A

Devensian glacial

27
Q

what was sea level in meters in the last ice age

A

around 100-125 m lower than today

28
Q

what did Evans in 1991 claim about how much ice could depress the land

A

that ice could depress the land beneath it by 0.3 times the thickness of the ice

29
Q

in the last ice age where was ice the thickest in Britain

A

over scotland, where isostatic readjustment is still occurring

30
Q

how much can land rise per day

A

20mm

31
Q

what is the effect of scotland still rising

A

causing parts of southern england to sink, isostatic fall

32
Q

define plate tectonics

A

the theory of the lovely of the plates that make up the earths crust

33
Q

what is orogenis

A

where at subduction zones, tectonic uplift occurs which produces fold mountains

34
Q

what is epeirogeny

A

localised tilting of the land

35
Q

what can a 1% increase in an area of the ocean cause to sea level

A

a 40 meter drop in sea level

36
Q

what process can reverse change by sea level rise

A

sea floor spreading

37
Q

what is thermal expansion

A

where rocks expand when heated and contract with when cooled

38
Q

how does thermal expansion cause sea level rise

A

when water heats up it rises

39
Q

describe a fjord

A

extremely deep
steep sided
drowned glacial lowland areas
U shaped cross-section

40
Q

how is a fjord produced

A

formed by drowning of glacial troughs
glaciers erode their valleys which create these troughs in the land, once the ice melts they’re flooded by eustatic rise

41
Q

describe a dalmatian coast

A

tigers that flow parallel to the coast
formed up to 50 million years ago

42
Q

how is a dalmatian coast formed

A

where glacial valleys or normal valleys lie parallel to each other so when sea level rises and floods the valleys, the top of the valleys is left exposed

43
Q

describe a raised beach

A

far back away from the coastline
former wave cut platform
higher than the sea level

44
Q

describe how a raised beach is formed

A

iso static rise causing the land to rise faster than sea level

45
Q

festive a marine platform

A

gently sloping platform that was formerly submerged
also known as a marine terrace
slope continues far offshore

46
Q

describe how a marine platform is produced

A

when sea level rises waves move sediment underwater back and fourth which acts like a sandpaper on bedrock, which makes it flat and smooth
so when sea level falls this platform emerges

47
Q

name 5 landforms created due to glacio-eustacy

A

bars, tombolos, estuaries, ria, fjord

48
Q

name two platforms causes by glacio-isostacy

A

marine platforms and raised beaches

49
Q

what is likely to be causing global warming

A

due to greenhouse gases and CO2 emissions from humans, by doing things like burning fossil fuels

50
Q

what are the two reasons for the prediction of sea level rise

A

ice is going to keep melting
thermal expansion is predicted to continue

51
Q

what are some impacts of sea level change

A

flooding
increased erosion
loss of coastal villages
power stations destroyed
loss of agriculture land
impact underground water sources

52
Q

what is the IPCC

A

intergovernmental panel on climate change

53
Q

what are the IPCCs projections for future sea level

A

to rise at around 4mm per year

54
Q

how much higher could sea level be by the end of the century

A

0.22 and 0.55m higher

Geog Coast BK 3 Sea Level Change (1 decks)

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