they form to stop the beach over loading with sand
sand dunes are created when a small shurb or plant becomes buried in sand then eventually the sand builds up to what we see today
wind forms them by blowing sand around.
Wind and waves form sand dunes on the beach
Sand Dunes. Aeroflot
Dunes are formed through the interaction of mountains and wind. The wind picks up quartz grains from the mountains in the area to form the dunes and these are reshaped by the same process over time.
barchan dunes
weathering
Erosion and Depositionerosion causes dunes and valleysdepostion causes deltas
Centuries
sand dunes
barchan dunes
Both form weather dune is has sand delta water
Wind erosion and deposition may form sand dunes and loess deposits.
it formed from ancient sand dunes.