Answer:
They act as barriers whereby wind deposits its load to come up with major land forms in the desert.
Step-by-step explanation:
Sand dunes retain the load that arises as a result of erosion processes ,and disposition.
Wind deposits con form hills and sand sheets .
An example of this is in California , whereby Sand dunes make up to 25 % of the land-forms in the arid areas .
Sand dunes can also influence the formation of oases , as a result of wind action.