sea level change Flashcards

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1
Q

what is eustatic sea level change

A

the rise or lowering of sea levels due to a change in the volume of water in the oceans

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2
Q

what is isostatic sea level change

A

the rise or lowering of sea levels due to a regional uplift or subsidence of the land, land moves relative to sea

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3
Q

how will land moving vertically down affect sea levels

A

sea levels will significantly decrease

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4
Q

what are the types of eustatic sea level change

A

-thermal expansion of water
-glacio eustatic sea level rise

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5
Q

what is thermal expansion of water

A

as global temps rise, the oceans get hotter. water will expand by 4%

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6
Q

what is glacio eustatic sea level rise

A

as world temps get hotter, big ice sheets start to melt, releasing huge amounts of trapped water into the oceans causing a rise in the sea level

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7
Q

what is an example of glacio eustatic sea level rise

A

Antarctica is losing ice mass (melting) at an average rate of about 150 billion tons per year,

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8
Q

what are the types of isostatic sea level change

A

-isostatic adjustment/rebound
-subsidence
-orogeny

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9
Q

what is isostatic rebound

A

as ice sheets melt over thousands of years time, it releases pressure on the land and over a very long time the land slowly starts to move back up.

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10
Q

what is subsidence

A

when land becomes water logged, it collapses. this causes a decrease in the relief of land

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11
Q

how can volcanoes affect the relief of land

A

repeating lava flows can build up land as they cool down

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12
Q

what is orogeny

A

new mountains forming through the collision of two plates. such as the oceanic and continental plates moving together

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13
Q

how has sea level changed in the past 10,000 years

A

during the last ice age 110,000-12,000 years ago,sea level was 130m lower than present. in the last 10,000 years ice sheets have started to melt. global sea level is currently rising at about 2mm a year due to thermal expansion of water, global temps have risen by 1.08 degrees between 1900 and 2016.

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14
Q

how has sea level changed in the past 10,000 years

A

during the last ice age 110,000-12,000 years ago,sea level was 130m lower than present. in the last 10,000 years ice sheets have started to melt. global sea level is currently rising at about 2mm a year due to thermal expansion of water, global temps have risen by 1.08 degrees between 1900 and 2016.

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15
Q

how many mm a year is sea level rise expected to be by 2100

A

8-15mm a year

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16
Q

what impacts do humans have on sea level rise

A

-greenhouse gas emissions have caused thermal expansion of water

17
Q

what occurs quicker, eustatic or isostatic

A

eustatic

18
Q

what are some differences between eustatic and isostatic sea level change

A

-isostatic takes a longer time
-eustatic is global
-isostatic is regional
-eustatic the sea changes in relation to land
-iostatic is where land changes in relation to sea

19
Q

what does submergence mean

A

when sea levels rise and land is flooded/drowned. also known as marine transgression

20
Q

what landforms appear due to marine transgression

A

-rias
-fjord
-dalmation coastline

21
Q

what is a ria and how is it formed

A

A ria is a valley that has been partially submerged by water near a coastline, formed by a rise in sea level

22
Q

what is the long and cross profile of a ria like

A

wide and deep at the mouth and becomes narrower and shallower as it gets further inland

23
Q

what is an example of a ria

A

kingsbridgeestuary devon

24
Q

what is a fjord

A

a drowned glacial valley (u-shaped valley)

25
Q

how are fjords formed

A

-during cold periods snow and ice build up to form a glacier
-the glacier flows down slope under the force of gravity (basal slippage)
-as the glacier moves it grinds subglacial sediment into the rock below it
-forms a u shaped valley
-warmer conditions causwe glacier to melt and leave behind the u shaped valley
-thermal expansion of water has causes a rise in sea level and u shaped valley is flooded
-entrance to fjord is shallow, called a threshold

26
Q

what is sublimation

A

the conversion of a substance from solid to gas without being a liquid

27
Q

what is an example of a fjord

A

the sognefjoden fjord in norway

28
Q

how long is the sognefjoden fjord

A

over 300km long

29
Q

what is the entrance to a fjord called and why it it shallow

A

a threshold, its shallow because it has a raised bit of land formed by deposition of material by the glaacier

30
Q

what is a dalmation coastline

A

a series of elongated islands that sit parallel to the coastline, result of sea level rise

31
Q

hat sort of coastline is needed for a Dalmatian coastline ti form

A

a concordant coastline