Deflation, in geology, erosion by wind of loose material from flat areas of dry, uncemented sediments such as those occurring in deserts, dry lake beds, floodplains, and glacial outwash plains. Clay and silt-sized particles are picked up by turbulent eddies in wind and may be carried for hundreds of kilometres; they later settle to form loess deposits. Local areas subjected to deflation may result in deflation hollows or blowouts. These may range from 3 m (10 feet) in diameter and less than a metre deep to several kilometres in diameter and several hundred metres in depth.