3.1.3.3 PPQ

Question 1

Outline the factors leading to the formation of Fjords (4)

Answer 1

Fjord is an example of coastal landform of submergence. A glacier carves its way creating a glacial trough.The flooding of the valley its due to eustatic rise being faster then isostatic adujustment.Fjords have a shallow entrance due to a threshold from sediment being deposited by the melting of glaciers. One example of a fjord is Sogne Fjord in Norway.

Question 2

Where do salt marshes tend to develop?(1)

Answer 2

In estuaries with an ample supply of sediment, often on the
landward side of spits.

Question 3

Explain the difference between eustatic, isostatic and tectonic sea level change.(4)

Answer 3

Eustatic Sea level change is a global change in sea level resulting in an actual fall or rise in the sea level relative to the centre of the earth. One example of eustatic sea level change is thermal expansion due to higher temperatures. Isostatic sea level change is a local change in sea level from land rising or falling relative to the sea. For example the melting of heavy glaciers cause isostatic rebound which causes a decrease in local sea level. Tectonic sea level change is change of sea level that is local due to movement of plates. One example is Dalmatian coasts.

Question 4

Outline the processes which lead to the development of barrier beaches.(4)

Answer 4

A barrier beach is usually formed as an extension to a spit (1).
* Longshore drift moves sediment along the coastline until there is a change in the coastline
(1). A spit develops, usually in a bay and once the spit develops across the whole bay, a
barrier beach forms (1). Barrier beaches are unlikely to form in estuaries as the outcoming
force of freshwater will always keep part of the estuary clear (1).
* Colonisation by vegetation can stabilise the barrier beach and trap further sediment
keeping the barrier beach above sea even at high tide (1).
* Depending upon the climate the landward side may be colonised by mangroves in the still
lagoon, which adds further stability (1).

Question 5

Outline the concept of eustatic sea level change(4)

Answer 5

Eustatic sea level change is a global change in sea level due to an actual fall or rise in the
level of the sea (1) − mark for any clear definition.
* When global temperatures fall, during a glacial period, more precipitation falls as snow and
is stored on land as ice and snow (1). Water cycled from the sea to the land (via
evaporation, condensation and precipitation) does not immediately return to the sea so
global sea levels fall (1)(d).
* Or the opposite. As global temperatures rise, during an interglacial or due to enhanced
global warming, more precipitation falls as rain, and snow and ice melt. (1). Less water is
stored on land and returns to the sea, so global sea levels rise (1)(d).

Question 6

Explain the development of saltmarsh environments.(4)

Answer 6

Salt marshes tend to develop in sheltered estuaries behind spits (1). As the spit develops,
the area behind it becomes sheltered (d).
* Silt is deposited by the river which gradually builds up to form an inter-tidal mud flat (1).
The mud flat continues to build and rise above sea level with the addition of further silt (1).
* Vegetation which is highly adapted to environment colonises the mud which itself traps
further sediment (1).
* The salt marsh environment is colonised by halophytic vegetation (1).