most likely in places that are sandy or have a lots of sand and great wind
barchan dunes
Quartz
Wind and waves form sand dunes on the beach
barchan dunes
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.
weathering
Erosion and Depositionerosion causes dunes and valleysdepostion causes deltas
sand dunes
Centuries
barchan dunes
Both form weather dune is has sand delta water