Coastal Depositional Landforms Flashcards
Where does coastal deposition landforms occur?
Low energy coastlines when the waves don’t have enough energy to carry a large sediment load, so deposit material
Explain how beaches are built up due to constructive waves:
Swash - aligned beaches form where energy is low, waves are more parallel to the shore so there is very little horizontal or lateral movement of sediment
How is spit formed?
Created as longshore drift moves sediment along the beach as the wave approaches at an oblique angle, when the coastline changes direction the waves no longer have energy to carry sediment so deposit it, the build up of sediment out to sea often into an estuary is called a spit (stops it forming a bar), the split often has a curved end or hooks due to a secondary prevailing wind
How are tombolo’s and bar’s formed?
As spits form across an estuary or around a headland they can form a bar, where sediments meets either an island or opposite headland, formed in the same way through LSD and deposition, bars can also form offshore, these are raised ridges of sediment away from the shore, they form where the sediment level is high and the sea is shallow, bars that form as spits extend ro join two headlands forming a barrier beach, the water trapped behind the barrier beach is called a lagoon (eg. Slapton ley at slapton sands)
How are salt marshes formed?
Behind spits and barrier beaches (very sheltered areas) where tidal currents and river currents meet leading to lots of deposition, salt tolerant species colonise this area, they are covered at high tide but exposed at low tide
How are sand dunes formed?
Sand accumulates on the beach from longshore drift! At low tide the sand dries out allowing the prevailing winds to move the loose sand up the beach, Large inter tidal zone for sand to be dry, Sand is transported by process of saltation, Debris on beach traps sand (This is called a strand line), Grass (eg. Lyme Grass) grows which stabilises the dunes
