Sea level change

Question 1

Name 3 factors effecting sea level change

Answer 1

• high & low tides
• atmospheric air pressure
• winds

Question 2

Definition of isostatic change

Answer 2

local rise/ fall in land level

-occurs when crust is forced down into mantle changing relative sea level

Question 3

Definition of eustatic change

Answer 3

rise/ fall in water level

-caused by change in vol of water

Question 4

Name 3 reasons for contemporary sea level change

Answer 4

global warming- melting of- mountain glaciers, polar ice sheets- increasing amount of water in ocean

• thermal expansion- increases oceans temperature- causing water to expand
• tectonic activity- geothermal heat- water to expand

Question 5

When do emergent coastlines form

Answer 5

• when water level has fallen- exposing land previously covered by sea
• when land has risen

Question 6

What are emergent coastlines

Answer 6

coastlines that have formed where water level has fallen/ land has risen

-happens due to isotatic change

Question 7

What are submergent coastlines

Answer 7

coastlines that have been flooded due to rise in sea levels

-happens due to eustatic sea level change

Question 8

Name 2 emergent coastline landform and how it forms

Answer 8

-raised beaches- as land rises due to isostatic recovery- beaches are raised above present sea level

-Fossil cliff
a steep slope found at the back of a raised beach, above tide level

Question 9

Name 3 submergent coastline landform and how it forms

Answer 9

-rias- form when valleys in dissected area are flooded
(example- kingsbridge devon)

• dalmatian coasts- rivers flow parallel to coasts (Dalmatian coast- Croatia)
• fjords- form when deep glacial troughs are flooded by rise in sea level (Norway)

Question 10

When does a eustatic rise in sea level occur

Answer 10

• end of glacial period -> melting ice sheets return water to sea -> sea levels rise
• global temp increases -> vol of ocean water increases -> sea levels rise

Question 11

When does a eustatic fall in sea level occur

Answer 11

-during glacial periods -> ice sheets form on land -> water evaporates from sea -> locked on land as ice -> fall in sea level

Question 12

When does a isostatic rise in land level occur and what does this cause for sea level

Answer 12

• post glacial adjustment- where earths crust was formerly depressed under ice sheets, crust rises as ice sheets recede -> fall in sea level
• accretion-sink regions in sediment cell are experiencing deposition -> land built up -> fall in sea level

Question 13

What is a ria

Answer 13

drowned river valley caused by sea level rise

Question 14

What are barrier islands

Answer 14

offshore sediment bars

Question 15

Name 2 reasons for longer-term sea level change

Answer 15

• eustatic change

- isostatic change

Question 16

How does global warming affect sea level change

Answer 16

• > eustatic sea level rise
• > melting of mountain glaciers, polar ice sheets -> water in the ocean store increases
• > thermal expansion of existing ocean water as its temp rises

Question 17

How does tectonic activity affect sea level change

Answer 17

• eustatic change -> emission of geothermal heat -> thermal expansion of ocean water -> rise in sea level
• isostatic change -> faulting uplifts sections of crust -> rise in land

Question 18

What is post glacial adjustment

Answer 18

• process where earths crust was formerly depressed under ice sheers -> rises as ice sheets recede
• causes rise in local land level

Question 19

What is accretion

Answer 19

sink regions in sediment cell are experiencing deposition -> land is built up -> decrease in seas level

Question 20

When does a isostatic fall in land level occur and what does this do to sea levels

Answer 20

• subsidence -> deposition of sediment in large river deltas
• weight of sediment deposition overcomes threshold -> crustal sag

Question 21

Give an example of an area where post-glacial adujustment is occuring, what is happening to this place

Answer 21

• Scotland is rebounding upwards

- due to rise in land level -> fall in sea lvel

Question 22

Give an example of an area where accretion is occuring, what is happening there

Answer 22

contributed to chsnges hsown with river ZThames

-increased accumilation of sediment -> fall in land -> rise in sea levels

Question 23

Give an example of an area in the UK that is sinking isostatically

Answer 23

(land is sinking)

Land’s End in Cornwall

Question 24

Which part of Britain is experiencing isostatic fall in sea level

Answer 24

Northern Britain experiencing isostatic fall in sea level (land is rising)

Question 25

Which part of Britain is experiencing isostatic rise in sea level

Answer 25

Southern Britain experiencing isostatic rise in sea level (land is sinking)

Question 26

What are emergent coastlines prodcued by

Answer 26

post-glacial adjustment

Question 27

Give an example of a raised beach and fossil cliff -> emergent landforms

Answer 27

Scotland, Fife

Question 28

Give an example of a ria -> submergent landform

Answer 28

Kingsbridge, Devon

Question 29

What are fjords

Answer 29

drowned glacial valleys

-always U-shaped

Question 30

Give an example of a fjord -> submergent landform

Answer 30

Norway, Sognefjord

Question 31

What are dalmatian coasts -> submergent landform

Answer 31

rivers flow parallel to coasts

Question 32

How does global warming affect sea level change

Answer 32

• > eustatic sea level rise
• > melting of mountain glaciers, polar ice sheets -> water in the ocean store increases
• > thermal expansion of existing ocean water as its temp rises

Question 33

How does tectonic activity affect sea level change

Answer 33

• eustatic change -> emission of geothermal heat -> thermal expansion of ocean water -> rise in sea level
• isostatic change -> faulting uplifts sections of crust -> rise in land