In USDA soil taxonomy, a Psamment is defined as an Entisol which consists basically of unconsolidated sand deposits, often found in shifting sand dunes but also in areas of very coarse-textured parent material subject to millions of years of weathering. This latter case is characteristic of the Guiana Highlands of northern South America. A Psamment has no distinct soil horizons, and must consist entirely of material of loamy sand or coarser in texture. In the World Reference Base for Soil Resources (WRB), most Psamments belong to the Arenosols. However, Psamments of fluviatile, lacustrine or marine origin belong to the Fluvisols.
Psamments cover 3.4% of the global land mass. They occur throughout the world, being especially abundant in the deserts of Africa and Australia and on the ancient landforms of eastern South America. Areas dominated by Psamments also occur in other humid regions, notably in Florida and Nebraska (the Sand Hills).