Loess. Deposits of unstratified fine-grained, pale buff yellow mineral particles. The particles in loess consist mostly of silt (up to 60 percent; particles 0.05 to 0.005 mm in diameter), although some clay (10–20 percent; particles less than 0.005 mm) and fine sand (up to 7 percent; particles 0.1 to 0.25 mm) are also present. The minerals that make up the particles are mostly quartz, followed by feldspar, mica, kaolinite, and montmorillonite. The soils that form on loess tend to be neither too wet nor too dry, and the chemical properties of loess provide the soil with high levels of fertility. Loess covers nearly three-quarters of the surface territory of Ukraine. It is found at various elevations, including uplands, slopes, plains, and valley terraces. Only the mountains, the glaciated lacustrine plains of Polisia, and the floodplains of major river valleys are devoid of loess. The thickness of loess in Ukraine ranges from several tens of centimeters to 40 to 50 meters (near Dnipro); the most common thickness is 5 to 10 meters (as in the Podolian Upland and the Azov Upland).
[This article originally appeared in the Encyclopedia of Ukraine, vol. 3 (1993).]