Dunes Flashcards
Formation of dunes
Sand dunes are made of wind blown sand and are stabilised by a process called Plant Succession. Long low waves which roll onto the beach. A strong swash deposits beach material which forms a long, flat beach. These type of wave usually form when there is a short fetch
Halophytes
plants that can tolerate saline (salty) conditions
Conditions for a salt marsh to develop
- In sheltered areas where deposition occurs
- Where salt and fresh water meets
- Where there are no strong tides or currents to prevent deposition or accumulation
Dunes
Dunes are landforms formed from sand deposits that have been blown off the beach. Where sufficient sand is deposited and dries in the intertidal zone (foreshore) it is then transported by saltation by the blowing wind. Sand dunes only form where the rate of beach deposition is greater than erosion (positive sediment budget).
Stabilisation of dunes
Plant roots bind sediment together, making it harder to erode.
Plant stems and leaves covering the ground surface protect sediment from wave erosion and erosion form tidal or longshore currents when exposed at high tide
Pioneer plants
These are the first plants to colonise freshly deposited sediment.
They modify the environment:
- Stabilising sediment
- Adding organic matter that retains moisture, contributes nutrients and provides shade.
- Reduce evaporation in sand
Embryo dunes formation
form when seaweed driftwood or litter provides a barrier or shelter to trap sand
Marram grass features
- has waxy leaves to limit water loss through transpiration and resist wind-blown sand abrasion.
- has roots that can grow to 3m to reach down the water table and the stem can grow 1m a year to avoid burial by deposited sand.
- allows the dune to grow, rapidly forming a yellow dune
Hummus
As the marram grass and sedge grass dies, it adds hummus to the sand, creating soil
