Sediment transport EQ1 Flashcards
Why is longshore drift important?
- results In distinctive coastal landforms
How does longshore drift form a spit
-Prevailing winds at oblique angles will causes a net movement of sediment along the coastline. Processes like traction and saltation are important here for larger material. When the coastline changes direction, like at a river mouth, the longshore drift continues to carry sediment out into the water forming a spit.
What is created behind the spit?
A low energy environment is created snf fine material can be deposited through processes of gravity settling and flocculation for finer clays.
What may some halophytic plants do after the formation of a spit?
They may colonise and stabilise this area as a salt marsh.
What may happen if there are changes to the wind direction after the formation of a spit?
The spit may form ‘hooks’ to create a. distinctive ‘re-curved spit’.
What is a spit?
Spits are long, narrow ridges of sand or shingle that are attached to the land at one end known as the proximal end.
What is key to a spits stabilisation and how is this created`/
Salt marches and sand dune secession which are created through sediment transport caused by the process of longshore drift
how do salt marshes and sand dune succession form?
They form due to the presence of a surplus of sediment combined with the process of longshore drift, the dominance of constructive waves and an appropriate coastal configuration - presence of an estuary or change in direction of the coast.
how are recurved spits formed
they are formed when there’s two dominant directions of wind causing two directions of longshore drift or due to longshore drift and tidal action.
- can also be formed when wave refraction ‘bends waves’ around the tip of the spit and so causes the spit to become recurved such as Hurst Castle Spit.
how are bars formed?
- where sediment transport caused by longshore drift elongates a spit from one side of the river channel to the other.
What else does the formation of a bar create?
This created a lagoon behind the bar such as at Lady’s Island Lake in Ireland.
How are tombolos formed?
When a beach or bar connects two landmasses. they are formed when an offshore island refracts approaching waves so that there is a convergence of two directions of longshore drift.
what is a barrier island?
they are flat and lumpy areas of sand that are parallel to the mainland coast. They usually occur in chains.
