Why do silt deposits rarely form dunes?

Silt deposits rarely form dunes because of their physical behavior when transported by wind. While silt is more easily picked up by the wind than sand, it is also carried away much faster and over greater distances. Consequently, there are few signs of dunelike bed forms where silt is deposited; instead, it typically accumulates as sheets of loess.1

In contrast, true sand dunes are almost invariably built of particles of sand size, which are heavy enough to accumulate into mounds or ridges under the influence of wind and gravity. While silt can be a component of windblown sediments, its tendency to remain suspended or be transported far from its source prevents it from forming the stable, localized accumulations characteristic of dunes.123