Coastal landscape development and sea level change Flashcards
What is Eustatic change?
A global change in sea level resulting from an actual fall or rise in the level of the sea itself.
What is Isostatic change?
Local changes in sea level resulting from the land rising or falling relative to the sea
What is an example of eustatic change?
Climate gets colder - marking the onset of a new glacial period
More precipitation falls as snow - turns into glacial ice which acts as a store for water
Hydrological cycle slows down as water cycled from the sea to the land, does not return to the sea
Subsequently, sea levels fall
Following on from the example of eustatic change, how may isostatic change occur?
The weight of ice causes the land surface to sink. This affects only some coastlines and then to a varying degree
What is a fjord?
Former glacial valley drowned by rising sea levels
What are Rias?
Former river valley drowned by rising sea levels
Explain the concept of Rias and Fjords, carrying on from the isostatic explanation?
Climate will get warmer
Ice masses on land begin to melt
This starts to replenish the main store and sea level will rise locally (isostatic)
This floods the lower parts of the land to produce submerging features such as rias and fjords
How do raised beaches form?
As the ice is removed from land - land rises
If the rate at which the land uplifts is greater than the eustatic sea level rise, emergent features will form - raised beaches
What is an example of a raised beach?
Isle of Arran, Scotland - isostatic sea level change causing the north to rise because ice sheets were thickest in northern Scotland
What is an example of a Ria?
Kingsbridge Estuary in Devon
RIAS KISS ENORMOUS DOLPHINS
What is the percentage of the ocean which actually experiences thermal expansion?
10% - however this is predicted to increase into the 90% of the ocean that doesn’t experience it as of yet
What is a submerging feature of coastline?
Rias
What is another submerging feature of a coastline that isn’t a Ria?
Fjords
Where are Fjords famous in?
Finland and Norway
What is a submerged coastline called?
Dalmation coasts
What is a Dalmatian coast?
A submerged coastline which was once a series of valleys and ridges running parallel to the shoreline. As sea levels rise, only the tops of the ridges are visible (as islands).
Where are Dalmatian coasts famous in?
Croatian coast in the Adriatic
DALMATIANS CUT CORNERS in the APPLE
What is an emerging feature of a coastline?
Raised beaches
How do Rias form?
The floodplain of a river will vanish beneath rising waters, on the edges of uplands only the middle - and upper-course valleys will be filled with sea waiter, leaving the higher land dry and producing Rias.
How do Fjords form?
They have steep valley sides and are straight and narrow.
They are not deepest at the mouth, and have a shallower section at the end, known as the threshold
They are formed when the sea drowned the lower part of glacial valleys that were cut to a much lower sea level
What is isostatic uplift?
It is a local and relative change in sea levels controlled by the crusts response to the movement of ice.
How does isostatic uplift occur?
During an ice age, the weight of the ice on a landmasses causes it to sink. As the earth’s temperature begins to rise again the ice melts and the weight decreases causing the land to slowly rise back out of the sea.
What is the ‘bounce back’ motion that takes place during isostatic uplift?
The localised change in sea level, relative to the land
What is a raised beach?
A raised beach is an elevated area of a sloping ground, sitting above the present tide line. In the past this area was at sea level.
What does relict define as?
Something that has survived - for example structure of minerals after destructive processes have taken place
What are the impacts of sea level rise?
Warmer oceans will increase the severity of storms
The current will be affected through heating
Bangladesh will see a 1m rise in sea level - leading to 1/5 of the country being submerged and 30 million people displaced
How has sea level changed since 1993?
It has doubled
What is the total heat taken up by the oceans in the last century and a half?
1,000 times the annual energy use of the world’s population
How many tonnes of ice has Antartica lost in the last 25 years?
3 trillion tonnes
How many people live within 1m of sea level?
150 million
What is the predicted sea level change for 2100?
1m
What will happen if humans limit global warming to 1.5 degrees?
They will still rise by 52cm
What will happen if humans limit global warming to 2 degrees?
Sea levels will rise by 63cm
What will the 11cm difference of sea level between 1.5 and 2 degrees cost?
1.4 trillion dollars per year
What are swash aligned beaches?
Produced where the waves break in line (parallel) with the coast.
Swash & backwash movements move material up and down the beach producing the aforementioned beach profile features.
Swash aligned beaches are smoothy curved, concave beaches.
The beach face is orientated parallel to the fronts of the dominant waves. Beaches which face the waves are termed swash aligned.
What are drift aligned beaches?
Produced where waves break at an angle to the coast. The swash therefore occurs at an angle but the backwash runs perpendicular to the beach. As a result, material is transported along the beach via longshore drift.
