Wind blown materials, comprised primarily of silt with some fine sand and clay, are called

Wind-blown materials, comprised primarily of silt with some fine sand and clay, are called Loess. It is a fine layer rich in mineral material.
Loess is periglacial or aeolian sediment, defined as an accumulation of 20% or less of clay and a balance of roughly equal parts sand and silt, often loosely cemented by calcium carbonate. It is usually homogeneous and highly porous and is traversed by vertical capillaries that permit the sediment to fracture and form vertical bluffs.