Fore dune – They tend to be very yellow as they have limited vegetation so no real humus layers develop. Marram grass is the main coloniser and stabiliser.
Yellow dune – The colour darkens as organic material add nutrients and humus to the soil. Sea couch and marram grass stabilise the dune.

Grey dunes – Developing humus layers changes the colour of the dune form yellow to grey. Water retention is also increased (soil becomes damper and richer) due to more humus therefore more species of plants thrive e.g. Creeping willow, red fescue and dewberry. In time, the dune stops growing because the sheltered means that there is a lack of wind to blow the sand.

	Created by chidat about 10 years ago

Coastal Land forms: Dunes