Eolian sedimentary environment
Winds can transport many different-sized particles of material from the ground through the process of erosion. These particles might travel many kilometers until they deposit somewhere. Regions with scarce vegetation have too much dust and grain-sized particles that move and crush each other, increasing erosion. This process is known as eolic erosion.
The most prominent accumulations of wind deposits are the dunes. However, there are other smaller accumulations such as the ripples and other larger ones called Draas. Their main differences are in addition to size, is the wavelength between them.
Dunes are winds deposits, formations that are, in general, typical of deserts. Dunes are orientated according to the direction and speed of winds, to the presence of loose material, and vegetation. Strong winds transport material until it collides with an object or obstacle where it is deposited, originating a new dune.
Dunes are very dynamic formations that are constantly being remodeled by the direction and strength of the winds. Dunes always have a soft slope and a sharp one. The soft slope is directed to the area or region where the wind is coming from and is the product of the wind erosion on the same dune. The opposite sharp slope is protected from the wind and is the deposition place, where the wind losses strength and the carrying material falls, depositing in this side of the dune.
Sinkiang is a desert in China. Placing yourself at 39 05 52.46N 84 30 56.16E lets you appreciate the duned shape of the ground. By zooming in and out, you can notice the soft and sharp slopes that are forming each of the dunes and the distance between them.