Sea Level Change Flashcards
What is eustatic sea level change?
This where the sea level changes as a result of a change in the shape of an ocean basin or as a result of a change in the volume of water which causes global effects.
What causes a change in the volume of water in regards to eustatic change?
Thermal expansion.
Melting of icecaps.
When do eustatic changes occur?
During or after an ice age because freezing temperatures suspend the hydrological cycle.
What is frozen water stored as?
Glaciers.
Why do ocean basins change shape?
This is because of tectonic movement.
What will happen as the ocean basin gets bigger?
The sea level will fall.
Does eustatic change have global or local effects?
It has global effects.
What is isostatic change?
This is where the sea level changes because the height of the land changes.
What happens when the height of the land decreases?
The sea level rises.
What happens when the height of the land rises?
The sea level decreases.
Is isostatic change a global or local change?
Local.
When does compression occur?
This occurs during an ice age.
What is compression?
This is where ice builds up on land causing it to sink because of the weight leading to sea level rise.
What happens after an ice age in regards to isostatic sea level change?
Decompression occurs slowly, this is also known as isostatic rebound.
What is isostatic readjustment?
This is the movement of a land as a result of ice moving on or off it.
What is tectonic sea level change?
This is where tectonic plates affect the sea level by either creating mountains or widening the ocean basin. It involves uplift and depression along some plate boundaries.
When do emergent landforms appear?
They appear at the end of an ice age where isostatic readjustment is faster that eustatic rise as the lands height rises faster than that of the sea.
What are signs of emergent features?
Coastal erosional landforms that appear above the current sea level. This is because they developed when the sea was at that level.
What type of a landform is a raised beach?
This is an emergent feature.
What raised beach?
This is a former wave cut platform where the beach is higher than the present sea level.
Are emergent features still subject to marine erosion?
No
What emergent features does the Isle of Arran have?
It has a raised beach that is north of Drumadoon.
It also contains a relict cliff, arches, stacks and caves including King’s Cave.
What are the different emergent features?
Raised beach
Relict cliff
What are submergent landforms?
These are where flood planes vanish due to rising sea levels drowning river valley.
What are rias?
These are drowned river valleys.
How are rias formed?
High land is dry whilst the middle and upper course valleys are filled with sea water.
What features do rias have?
They have a long section and a cross profile that is typical of a river valley as well as a dendritic system of drainage.
What are fjords?
These are drowned glacial valleys.
What features do fjords have?
They are straight and narrow with steep sides and a U shaped cross section that is similar to glacial valleys.
What does the cross section of a fjord have on either side?
It has hanging valleys on either side.
Where are rias deepest?
At the mouth.
What do fjords usually consist of?
A glacial rock basin with a shallower section at the end which is called a threshold.
What is the threshold of a fjord thought to be the result of?
It is thought to be a result of glacial erosion when the glacier came into contact with the sea and the ice became thinner.
How do fjords form?
They form when the sea drowns the lower part of the glacial valley which was cut to a much lower sea level.
How long is Sogne Fjord, Norway?
Nearly 200km long
What is a Dalmation coast?
This is a set of flooded valleys that run parallel to the coast.
How are Dalmation Coasts formed.
They are formed when the sea floods the the valleys that are parallel to the coast.
What can be seen at a Dalmation coast?
Islands and peninsulas are aligned parallel to, but just offshore from the mainland.
What do rias and fjords have in common?
The flooded valleys run perpendicular to the coast.
What is continental ice?
This is freshwater ice sheets that form on land.
By how much have sea levels been rising each year in the past millennia?
1-2mm per year.
The rate of sea level rise has increased recently to what?
4-5mm per year.
What are future predictions for sea level rise?
Between 0.3 and 0.5m increase by 2090.
What are the social impacts of sea level rise?
People lose their homes Less jobs Population displacement More crime Overcrowding Increase in transmission of water borne diseases.
What are the economic impacts of rising sea levels.
Loss of coastline so less tourism Loss of land for farming Can't sell homes Cost of sea defences Flood damage
What are the 3 environmental impacts of rising sea levels?
Loss of coastline
Loss of habitats
Flooding
What are the political impacts of rising sea levels?
Conflicts in regards to coastal protection
Conflicts with housing issues
Border control
What are the other issues associated with sea level rise?
Impact on underground water resources.
Intrusion of salt water beneath the land could contaminate fresh water stores.
Abstraction points need to be moved upstream or further
inland.
Coastal squeeze in salt marshes
Ecosystems may not be able to adjust in time.
What are the two main socio-economic impacts?
More developments are occurring at risk areas like flood planes
Insurance is expensive
