The Creation of Sand DunesThere are five main steps to the creation of sand dunes:A strong sea breeze blowing inland will pick up grains of sand and move them onto the beach . This happens when the tide goes out and the sand on the beach dries out. The grains of sand will continue to move with the wind and will not stop until they find something in their way. At the top of the beach there is usually a beach line, made up of seaweed and rubbish left by the tide. Grains of sand jump over this beach line and collect where the air is calm. This creates a small embryonic dune. The dune can be easily destroyed unless it is colonized by plants. Seagrass is the most common plant that can grow on dry, salty sand. The sand is then tied together with the help of the long roots of the seagrass. The dune will grow as more and more sand is trapped. The prickly grass will then colonize the dune and replace the couch grass once the dune reaches a height of about one meter. For the prickly grass it is not problematic to obtain water since its long roots are fifteen to twenty meters long. This becomes a super sand trap and the marram-covered dunes can grow in height by one meter per year. A dune ten to twenty meters high is called a yellow dune, and there is a possibility that a new embryonic dune will form in front of it. Conditions at the back of the dune become less windy and less sand instantly accumulates behind it once the yellow dune is about ten meters high. When the marram grass dies, it rots on the dune adding humus to the sand. The combination of humus and sand forms a soil in which other plants can grow. These can include dandelions and resharrows. This type of dune is called a semi-fixed dune. Soil depth increases over time and so does the soil